COURT OF APPEAL FOR ONTARIO

DATE: 20210729 DOCKET: C68655

Strathy C.J.O., Feldman and Sossin JJ.A.

BETWEEN

Armen Hacopian-Armen as Litigation Administrator for the Estate of Armineh Hacopian-Armen, deceased, Armen Hacopian-Armen as Estate Trustee for the Estate of Vrijouhi Casper, deceased and Armen Hacopian-Armen, personally

Plaintiffs (Respondents)

and

Dr. Haidar Mahmoud, Dr. Hassan Deif, Dr. Neil Isaac, and North York General Hospital

Defendant (Appellant)

Counsel: Kosta Kalogiros and Brittany Cerqua, for the appellant Christopher I.R. Morrison and Paul J. Cahill, for the respondents

Heard: May 20, 2021 by video conference

On appeal from the judgment of Justice Carole J. Brown of the Superior Court of Justice, dated August 19, 2020, with reasons reported at 2020 ONSC 4946.

Strathy C.J.O.:

A. Background

[1] This appeal raises issues of factual and legal causation in the context of a medical negligence action.

[2] Armineh Hacopian-Armen died on August 24, 2011, as a result of Stage IV uterine leiomyosarcoma (“uLMS”), which had metastasized to her lungs. The respondents, members of her family, brought this action against the appellant, her gynecologist. They alleged that the appellant was negligent when he examined Ms. Hacopian-Armen on May 25, 2009, in failing to conduct an endometrial biopsy, a simple in-office procedure for the detection of uterine pathologies and abnormalities. The respondents claimed that this would probably have detected her cancer at an early stage, when treatment would likely have been effective.

[3] The trial judge found that: the appellant breached the applicable standard of care; Ms. Hacopian-Armen and family members had suffered damages as a result; the damage was foreseeable; and the appellant’s negligence was causative of the damages.

[4] On appeal, the appellant does not challenge the trial judge’s finding that he breached the standard of care by failing to perform an endometrial biopsy. He alleges, however, that the trial judge erred in concluding that his breach of duty caused Ms. Hacopian-Armen’s death.

B. Facts

[5] To appreciate the issues in this appeal, it is necessary to understand the nature and progress of Ms. Hacopian-Armen’s condition and the course of treatment she received.

[6] Ms. Hacopian-Armen was diagnosed with fibroids in 1999. Fibroids, also called leiomyoma, are benign, non-cancerous growths that develop in smooth muscle tissues. Uterine fibroids develop in the myometrium, the smooth muscle of the uterus. Fibroids are common, but the majority are asymptomatic – they are frequently very small and cause no problems. They can, however, grow to a significant size, and their size and location can cause pain, heavy bleeding and other symptoms. Fibroids can be treated in several ways, including a procedure known as uterine artery embolization, in which the blood supply to the fibroid is restricted, causing it to shrink and the symptoms to subside.

[7] Counsel called uLMS the “evil twin” of fibroids. It is a rare form of cancer that, like fibroids, also originates in the myometrium. It has features similar to fibroids and cannot be distinguished from fibroids on imaging. For that reason, it frequently goes undetected. It is a very aggressive form of cancer and there is often a poor prognosis when it is discovered.

[8] The uterus has a hollow inner cavity. The interior lining of the uterus is called the endometrium. It, in turn, is surrounded by the muscular wall of the myometrium.

[9] An endometrial biopsy was described by the experts as a simple procedure that can be done in a gynecologist’s office and takes only a minute or two. A narrow, straw-like instrument, called a “cannula” or “pipelle” is inserted through the cervix into the uterine cavity. There, it can be manipulated to suction out a small sample of tissue. The tissue sample can then be tested to detect the presence of uterine malignancies or abnormalities, including uterine and endometrial cancers. Depending on certain conditions, discussed by the experts at trial, it may also detect uLMS.

[10] In 2004, some five years after the diagnosis of her fibroids, Ms. Hacopian-Armen began to experience heavy bleeding, with clots, during her menstrual periods. This bleeding lasted approximately two weeks each month. In 2009, her family physician referred her to the appellant for treatment.

[11] At her first appointment with the appellant on May 25, 2009, she presented with what the respondents’ experts described as several risk factors for diseases of the uterus and “intrauterine pathology”: she was over 40 years old (in fact, she was 47); she was experiencing abnormal uterine bleeding (“AUB”); and she was “nulliparous” – she had never given birth to a child. The appellant took a vaginal swab but did not perform an endometrial biopsy. He referred her to another physician to discuss the possibility of treating her fibroids with uterine artery embolization.

[12] A few months after her first appointment with the appellant, Ms. Hacopian-Armen began to experience several health problems. In August 2010, she visited the emergency room four times because she felt weak, had heart palpitations, or was short of breath. These visits to the ER led to a variety of tests, which revealed that she had deep vein thrombosis (“DVT”) and pulmonary nodules.

[13] In February 2011, two new lung nodules were discovered during a CT scan. In March 2011, Ms. Hacopian-Armen met with a specialist in respiratory and internal medicine at North York General Hospital. The specialist noted that her recurrent DVT and the new lesions on her lungs indicated that she possibly had cancer. The specialist sent a consultation request to the appellant indicating that she needed a Pap test as soon as possible.

[14] On April 7, 2011, the appellant performed an endometrial biopsy, which indicated that Ms. Hacopian-Armen had a high-grade cancerous tumour in her uterus, likely uLMS. At this point, her cancer had metastasized to Stage IV.

[15] In May 2011, Ms. Hacopian-Armen had a hysterectomy and began chemotherapy. Despite these treatments, the disease progressed. Ultimately, she died on August 24, 2011.

C. The Trial Judge’s Reasons

(1) Overview

[16] There were three issues before the trial judge: the standard of care, factual causation, and legal causation. The trial judge concluded at para. 156 that: (i) the appellant breached the standard of care that he owed to Ms. Hacopian-Armen by failing to perform an endometrial biopsy; (ii) a biopsy performed at the first appointment on May 25, 2009 would have detected the uLMS and thus significantly improved her prognosis; and (iii) the harm that occurred was foreseeable and related to the appellant’s failure to perform the biopsy.

[17] I will explain the trial judge’s analysis and conclusions on each of these three issues, but first I will explain the role of expert evidence at the trial.

(2) Expert Witnesses

[18] The trial judge’s acceptance of the evidence of the respondents’ experts, in preference to that of the appellant’s experts, figured large in her findings of fact: at para. 90. The respondents’ experts provided opinions on the standard of care, causation, and the identification of metastatic disease. While the appellant contested the respondents’ submissions on the standard of care, he led no evidence on this issue. His experts only provided opinions on causation. I will identify the principal experts.

(a) Respondents’ Experts

[19] Dr. Allan Covens was a specialist in gynecological oncology – that is, the diagnosis and treatment of cancers of the female reproductive system. He held the position of Chair of the Division of Gynecologic Oncology in the Department of Obstetrics and Gynecology at the University of Toronto. He was also the head of the Division of Gynecologic Oncology at the Odette Cancer Centre at Sunnybrook Hospital in Toronto. He runs a weekly gynecology-oncology clinic, which investigates AUB, among other things. He was qualified to give evidence on the issues of standard of care and causation.

[20] Dr. Andrew Browning was an obstetrician and gynecologist with some 27 years’ experience. He had served for two years as Chief of Obstetrics and Gynecology at the Royal Victoria Hospital Regional Health Centre in Barrie, Ontario. He had extensive experience treating fibroids and AUB. He was qualified to give evidence on the issues of standard of care and causation.

(b) Appellant’s Experts

[21] Dr. George Vilos was an obstetrician and gynecologist with a primary appointment as a gynecologist in the Department of Obstetrics and Gynecology at the London Health Sciences Centre. He was also a professor in the Department of Obstetrics and Gynecology at the Schulich School of Medicine at the University of Western Ontario. He gave evidence in relation to causation and the likelihood of detecting uLMS with an endometrial biopsy.

[22] Dr. Nicholas Leyland was a specialist in gynecological oncology, focusing on general gynecology. His evidence was confined to the likelihood of detecting uLMS with an endometrial biopsy.

[23] Dr. Jason Dodge had been a gynecological oncologist until August 2015 and, at the time of trial, had been practicing gynecology in general practice. He was qualified to give evidence on causation.

(c) The Trial Judge’s Assessment of the Expert Evidence

[24] The trial judge specifically commented on the credibility of the experts, all of whom were well qualified in their fields. She found the evidence of the respondents’ experts, Dr. Browning and Dr. Covens, to be “forthright, impartial and consistent” and found their testimony to be credible.

[25] In contrast, while the trial judge found the appellant’s experts to be knowledgeable, she found their evidence in cross-examination contradicted their evidence-in-chief, they were less than forthright in cross-examination and were argumentative.

[26] At para. 90 of her reasons, she explained that she preferred the evidence of the respondents’ experts:

Based on the evidence, the medical records, the agreed statements of fact, the reports and testimony of the experts, where there is a discrepancy between the testimony of the plaintiff’s experts and the testimony of the defendant’s experts, I prefer the evidence of the plaintiff’s experts, unless I state otherwise.

[27] As I will explain, in an appeal that is largely fact-based, the trial judge’s assessment of the frequently conflicting evidence of experts is entitled to deference in the absence of palpable and overriding error.

[28] Against this background, I turn to the trial judge’s findings in relation to the issues before her.

(3) Part I: The Standard of Care

[29] The trial judge first considered whether the appellant breached the applicable standard of care by failing to perform an endometrial biopsy. At para. 104 of her reasons, she set out the standard of care as that of a reasonable and prudent physician of the same experience and standing, having regard to all the circumstances of the case.

[30] The trial judge found that the appellant had breached the standard of care by failing to consider and perform an endometrial biopsy as recommended by the Guidelines of the Society of Obstetricians and Gynecologists of Canada for the Management of AUB (the “Guidelines”). The Guidelines recommended an endometrial biopsy for patients over 40 who experienced AUB, in order to rule out abnormal pathologies. Ms. Hacopian-Armen presented with both risk factors.

[31] The appellant argued that he did not contravene the Guidelines because Ms. Hacopian-Armen did not have AUB. Without this risk factor, he contended, a biopsy was not required. The appellant submitted that she did not have AUB because her menstrual period occurred regularly, every two weeks, and the heavy bleeding was attributable to her fibroids. The trial judge rejected this submission. Ms. Hacopian-Armen’s heavy bleeding began five years after she was diagnosed with fibroids. The trial judge accepted the respondents’ expert’s opinion that two weeks of heavy bleeding per month was highly abnormal: at para. 115.

(4) Part II: Factual Causation

[32] The trial judge’s causation analysis turned on three questions, set out at para. 96 of her reasons:

1. Did Ms. Hacopian-Armen have uLMS at the time of her first appointment with the appellant on May 25, 2009?
2. If so, would an endometrial biopsy performed on May 25, 2009 have detected abnormal pathology or uLMS?
3. If so, would her prognosis likely have been substantially improved as a result?

[33] Both of the respondents’ experts opined that Ms. Hacopian-Armen likely had Stage I uLMS on May 25, 2009: at para. 149.

[34] Dr. Browning testified that her AUB in May 2009 was likely caused by the presence of cancerous cells in her uterus. Both Dr. Browning and Dr. Covens testified that uLMS was likely present on May 25, 2009 because the cancer had reached Stage IV by April 2011. The trial judge accepted this evidence: at para. 149.

[35] The trial judge also accepted the respondents’ experts’ opinions that an endometrial biopsy performed on May 25, 2009 would have likely detected abnormal pathology or uLMS: at para. 146. The medical literature explained that the sensitivity for the detection of uLMS is increased in patients who are menopausal. Dr. Browning and Dr. Covens testified that, in their opinion, women who are nulliparous have a much greater likelihood of early menopause and Ms. Hacopian-Armen was probably close to menopause. The trial judge accepted this evidence and found that Ms. Hacopian-Armen was “hormonally closer to post-menopause than pre-menopause” given her age and the fact that she was nulliparous: at para. 146.

[36] The appellant relied on scientific studies to argue that it was unlikely that an endometrial biopsy could have detected the uLMS because imaging from 2009 showed that the uLMS had not yet broken through the endometrium into the uterine cavity. The trial judge rejected this argument, accepting the evidence of the respondents’ experts that it was likely that uLMS was in or near the endometrium, causing AUB, which would further increase the likelihood of detection.

[37] Finally, the trial judge found that Ms. Hacopian-Armen’s prognosis would have been substantially improved if the uLMS had been found and treated in 2009: at para. 150. The trial judge’s conclusion was, again, largely based on the evidence of the respondents’ experts. Dr. Browning noted that early intervention would have likely included a hysterectomy, which would have removed the cancer that had not yet metastasized to the rest of the body. Dr. Covens testified that treatment for the Stage I uLMS in 2009 would have effectively been a cure.

[38] Having found that she likely had uLMS at her first appointment with the appellant, that an endometrial biopsy would have likely detected abnormal uterine pathology or uLMS, and that her prognosis would have been substantially improved, the trial judge concluded that the respondents had proved factual causation on a balance of probabilities. In other words, but for the appellant’s failure to perform the biopsy in May 2009, Ms. Hacopian-Armen would probably not have died of Stage IV uLMS.

(5) Part III: Legal Causation

[39] On the third and last issue of legal causation, the trial judge considered whether Ms. Hacopian-Armen’s death was foreseeable and sufficiently connected to the appellant’s failure to perform an endometrial biopsy. She found that the risk of uLMS was real, and that it was not something that a “reasonable, skilled, specialist would have brushed aside as far-fetched”: at para. 155. She also concluded that it was foreseeable that the presence of uLMS, if not treated, would likely result in serious injury or death.

(6) Part IV: Disposition and Damages

[40] As a result of her findings, the trial judge held, at para. 157, that the appellant was liable for his negligence. The respondents were awarded $300,000 in damages.

D. Issues on Appeal

[41] The appellant does not challenge the trial judge’s finding that he breached the standard of care by failing to perform an endometrial biopsy. He does, however, allege several errors in the trial judge’s analysis and conclusions on legal and factual causation.

(1) Legal Causation

[42] The appellant acknowledges that the trial judge correctly identified the principles of legal causation set out at para. 155 of her reasons. He submits, however, that her analysis was inconsistent with these principles and that she erred by engaging in a retrospective approach to causation. He asserts that the trial judge erred by asking whether it was foreseeable that the presence of uLMS, if untreated, would lead to serious injury or harm. According to the appellant, the correct question was whether uLMS, specifically, was foreseeable in May 2009.

[43] To answer this question, the appellant submits that the trial judge should have asked whether it would occur to a reasonable gynecologist that: (i) Ms. Hacopian-Armen had uLMS in May 2009; (ii) an endometrial biopsy would have diagnosed uLMS; and (iii) not performing an endometrial biopsy in May 2009 could lead to a delayed diagnosis of uLMS.

[44] The appellant also submits that the trial judge’s erroneous approach to legal causation would create a dangerous precedent, resulting in an increase of retrospective claims and would overburden the medical system by encouraging physicians to order unnecessary tests to avoid the risk of missing an unforeseeable disease.

(2) Factual Causation

[45] The appellant submits that the trial judge committed two reviewable errors in her analysis and conclusion on factual causation. First, he alleges that the trial judge erred when she found that uLMS was likely present in May 2009. According to the appellant, that error has three components: (i) admitting Dr. Covens’s testimony, despite the fact that his expert report did not comply with Rule 53.03 of the Rules of Civil Procedure; (ii) misapprehending Dr. Covens’s and Dr. Browning’s testimony on this issue and concluding that uLMS was likely present, despite the fact that there was no evidence to support that conclusion; and (iii) in stating, at para. 152, that the “defendants submit that there is no proof that uLMS was present on May 25, 2009” (emphasis added), when this did not reflect the appellant’s position. The appellant’s expert, Dr. Vilos, testified that the evidence showed that it was unlikely that uLMS was present in 2009, not that there was no proof. This misapprehension, the appellant says, went to the core of the defence theory on the absence of uLMS.

[46] Second, the appellant alleges that the trial judge erred in finding that an endometrial biopsy would have likely detected uLMS in 2009. He submits that a single paragraph of the trial judge’s reasons contains five palpable and overriding errors. I will identify and discuss these in the analysis section below.

[47] Ultimately, the appellant argues that the trial judge’s reasons were “overwhelmed” by these factual and analytical errors. The appellant asks that the trial decision be set aside, and the claim dismissed or that a new trial be ordered.

E. Analysis

[48] While the issues on this appeal relate to the trial judge’s conclusion on factual and legal causation, it is helpful to situate those issues in the context of the negligence analysis.

[49] A plaintiff asserting a claim in negligence must establish four things: (a) that the defendant owed the plaintiff a duty of care; (b) that the defendant’s conduct breached the applicable standard of care; (c) that the plaintiff sustained damage; and (d) that the defendant caused the damage in fact (factual causation) and in law (legal causation): Mustapha v. Culligan of Canada Ltd., 2008 SCC 27, [2008] 2 S.C.R. 114, at para. 3.

[50] There was no dispute at the trial about the existence of a duty of care, since Ms. Hacopian-Armen had been referred to the appellant for treatment of her fibroids. Nor was it disputed that she and her family members had suffered compensable damages, which were recoverable if negligence were established. The applicable standard of care and whether it had been breached, was very much in issue, as was causation.

[51] The standard of care and its breach took up a considerable amount of time at trial. Although the appellant did not adduce expert evidence on these issues, he challenged the evidence of the respondents’ experts, Dr. Covens and Dr. Browning. They testified that having regard to Ms. Hacopian-Armen’s AUB – heavy bleeding, with blood clots, for over 14 days each month – her age (47), and the fact that she was nulliparous, all of which increased the risk of some form of uterine pathology, an endometrial biopsy should have been performed to rule out uterine pathologies or other abnormalities that could have been causing her AUB.

[52] The appellant’s evidence was that he assumed that her bleeding was attributable to her fibroids, did not consider that there could be other potential causes of her bleeding and, on those assumptions, did not conduct an endometrial biopsy.

[53] The trial judge accepted the evidence of the respondents’ expert witnesses and found that the standard of care required an endometrial biopsy in such circumstances. She also found that the appellant had breached that standard.

[54] Although the evidence concerning Ms. Hacopian-Armen’s age, nulliparous state and abnormal bleeding was relevant to standard of care, it was also relevant to legal and factual causation because, in the opinion of Dr. Browning and Dr. Covens, it meant that she was probably close to menopause, making it more likely that an endometrial biopsy would detect her cancer.

(1) First ground of appeal: Did the trial judge err in finding legal causation?

[55] The appellant does not dispute that the trial judge identified the appropriate test for legal causation. Referring to Mustapha, the trial judge set out at para. 126 that the plaintiff must establish that the injuries suffered were “foreseeable or not too remote”:

[I]t must be determined whether the harm is too unrelated to the wrongful conduct to hold the defendant fairly liable. The injury must have been a real risk “which could occur to the mind of a reasonable man in the position of the defendant … and which he would not brush aside as far-fetched”.

[56] The trial judge’s findings on legal causation were summarized at para. 155 of her reasons:

In this case, I am satisfied that having failed to conduct an endometrial biopsy on the plaintiff at the first consultation which would have detected whether there was LMS present, it was foreseeable that the presence of LMS, if not treated, would likely result in serious injury or death to the plaintiff, which indeed, it did. I do not find the risk to be something that a reasonable, skilled, specialist would have brushed aside as far-fetched. Accordingly, I am satisfied that legal causation has also been established.

[57] The appellant submits the trial judge asked herself the wrong question and assessed causation with the benefit of hindsight, improperly blending her factual findings with her legal analysis. He submits that the question should have been whether it was foreseeable to a reasonable gynecologist that (a) Ms. Hacopian-Armen had uLMS in May 2009; (b) an endometrial biopsy would have diagnosed the uLMS; and (c) not performing an endometrial biopsy in May 2009 could lead to a delayed diagnosis of uLMS. Relying on the observations of Nash J. in Tilley v. Man Roland Canada, 1999 ABQB 364, aff’d 2002 ABCA 309, at para. 183, the appellant submits that “[o]ne cannot now, in hindsight, review the circumstances and conclude, based on the fact of the accident, that it was reasonably foreseeable or ought to have been foreseeable.” The appellant submits that uLMS is a rare form of uterine cancer, it was not foreseeable and the harm to Ms. Hacopian-Armen was too remote to fairly hold him liable.

[58] I accept the appellant’s submission that the trial judge inappropriately blended into her foreseeability analysis her finding of fact that an endometrial biopsy performed in May 2009 would have detected the presence of uLMS. The foreseeability analysis ought to have focused on the information reasonably available to the appellant in May 2009, when he failed to conduct an endometrial biopsy. However, on the correct analysis, it did not matter that the appellant was not aware that Ms. Hacopian-Armen had uLMS – what mattered was that the combination of her AUB, her age, and her nulliparous state, not only required an endometrial biopsy, but also made it reasonably foreseeable that the failure to conduct one would preclude detection of a uterine pathology that would cause her serious harm if left untreated.

[59] The appellant’s proposed foreseeability analysis is flawed because in focusing on the presence of uLMS, he inappropriately narrows the scope of the risk that he ought to have foreseen. The appellant was not required to foresee the presence of uLMS or the “precise concatenation of events”: R. v. Coté et al., [1976] 1 S.C.R. 595, at p. 604. It is sufficient that “the harm suffered must be of a kind, type or class that was reasonably foreseeable as a result of the defendant’s negligence”: Frazer v. Haukioja, 2010 ONCA 249, 101 O.R. (3d) 528, at para. 51. In failing to conduct a test that would have detected the presence of cancers of the “same class” or character as uLMS, including uLMS, it was foreseeable that uLMS or other malignancies would go undetected, with consequent injury to Ms. Hacopian-Armen: Ter Neuzen v. Korn, [1995] 3 S.C.R. 674, at para. 60.

[60] Based on the evidence accepted by the trial judge as to the circumstances that Ms. Hacopian-Armen presented with in May 2009, it was foreseeable to a reasonable gynecologist of the same experience and standing that the failure to perform an endometrial biopsy could preclude the detection of a uterine pathology or abnormality, which could lead to serious injury or death.

[61] I reject the appellant’s submission that the trial judge’s approach to foreseeability would require physicians to order unnecessary tests. The evidence accepted by the trial judge was that in the circumstances that presented themselves to the appellant on May 25, 2009, an endometrial biopsy was a necessary test and one that should have been performed by a competent gynecologist.

[62] I would therefore reject the first ground of appeal.

(2) Second ground of appeal: Did the trial judge err in finding factual causation?

[63] The appellant submits that the trial judge erred in finding factual causation – that is, on a balance of probabilities, “‘but for’ the defendant’s negligence, the injury would not have occurred”: Clements v. Clements, 2012 SCC 32, [2012] 2 S.C.R. 181, at para. 8.

[64] There are two branches to the appellant’s submission. The first branch, discussed in sub-section (a), below, asserts that the trial judge erred in finding that uLMS was likely present in May 2009. This branch has three parts, identified below. The second branch, discussed in sub-section (b), is that the trial judge erred in finding that an endometrial biopsy would have detected uLMS, had it been present.

[65] To a considerable extent, these submissions challenge the trial judge’s findings of fact or assert that the trial judge misapprehended certain evidence. For that reason, I begin with the applicable standard of review.

[66] A trial judge’s findings of fact are entitled to deference, particularly where those findings are based on findings of credibility in relation to conflicting evidence. As the Supreme Court observed in Housen v. Nikolaison, 2002 SCC 33, [2002] 2 S.C.R. 235, at para. 36:

To summarize, a finding of negligence by a trial judge involves applying a legal standard to a set of facts, and thus is a question of mixed fact and law. Matters of mixed fact and law lie along a spectrum. Where, for instance, an error with respect to a finding of negligence can be attributed to the application of an incorrect standard, a failure to consider a required element of a legal test, or similar error in principle, such an error can be characterized as an error of law, subject to a standard of correctness. Appellate courts must be cautious, however, in finding that a trial judge erred in law in his or her determination of negligence, as it is often difficult to extricate the legal questions from the factual. It is for this reason that these matters are referred to as questions of “mixed law and fact”. Where the legal principle is not readily extricable, then the matter is one of “mixed law and fact” and is subject to a more stringent standard. The general rule is that, where the issue on appeal involves the trial judge’s interpretation of the evidence as a whole, it should not be overturned absent palpable and overriding error. [Citations omitted.]

[67] That principle applies where, as here, the trial judge makes factual findings based on the assessment of the credibility of experts called by one party and rejection of the evidence of the other party’s experts: Lapointe v. Hôpital Le Gardeur, [1992] 1 S.C.R. 351, at paras. 16-23; Waxman v. Waxman, at paras. 300-1, leave to appeal refused, [2004] S.C.C.A. No. 291. The trial judge explicitly found the evidence of the respondents’ expert witnesses, notably Dr. Browning and Dr. Covens, to be more reliable than the appellant’s witnesses and she gave reasons for her conclusions. Where there was conflict between the experts’ evidence, she preferred the respondents’ witnesses.

[68] As this court emphasized in Waxman, at paras. 291-92, referring to the majority reasons in Housen, “there is one, and only one, standard of review applicable to all factual conclusions made by the trial judge” and the “‘palpable and overriding’ standard demands strong appellate deference to findings of fact made at trial.” Thus, as in Waxman, a “palpable” error may not be overriding if the impugned finding is supported by other evidence: at para. 297.

[69] In Waxman, at paras. 296-97, this court observed:

The “palpable and overriding” standard addresses both the nature of the factual error and its impact on the result. A “palpable” error is one that is obvious, plain to see or clear. Examples of “palpable” factual errors include findings made in the complete absence of evidence, findings made in conflict with accepted evidence, findings based on a misapprehension of evidence and findings of fact drawn from primary facts that are the result of speculation rather than inference.

An “overriding” error is an error that is sufficiently significant to vitiate the challenged finding of fact. Where the challenged finding of fact is based on a constellation of findings, the conclusion that one of those findings is founded on a “palpable” error does not automatically mean that the error is “overriding”. The appellant must demonstrate that the error goes to the root of the challenged finding of fact such that the fact cannot safely stand in the face of that error. [Emphasis added; citations omitted.]

[70] In Carmichael v. GlaxoSmithKline Inc., 2020 ONCA 447, 151 O.R. (3d) 609, at paras. 124-25, leave to appeal refused, [2020] S.C.C.A. No. 409, this court explained when a trial judge’s misapprehension of the evidence warrants appellate intervention:

In my view, therefore, the motion judge's finding that he had "no trouble" concluding that several of the Huang/Hengeveld indicators of capacity were not met reflects a misapprehension of the evidence. A misapprehension of the evidence "may refer to a failure to consider evidence relevant to a material issue, a mistake as to the substance of the evidence, or a failure to give proper effect to the evidence". Here, the motion judge made a mistake about the substance of the evidence and failed to give proper effect to the evidence, by finding that the evidence showed that several of the Huang/Hengeveld indicators of capacity were absent, when that was not so.

A misapprehension of evidence justifies appellate intervention where it is palpable and overriding, that is, where the misapprehension is obvious and goes to the very core of the outcome of the case. That is so here, because the motion judge's misapprehension is obvious and was essential to his conclusion that Mr. Carmichael was incapable of suing GSK until December 2, 2009, because of his psychological condition. [Emphasis added; citations omitted.]

[71] In Benhaim v. St. Germain, 2016 SCC 48, [2016] 2 S.C.R. 352, itself a medical malpractice case, the majority of the Supreme Court emphasized that a trial judge’s findings of fact are entitled to deference when they are based on her assessment of all the evidence, including medical literature and the conflicting evidence of experts: at paras. 37, 72, 75 and 84. It cautioned, at para. 84, that “[a]ppellate courts must be cognizant of the risk of ‘tunnel vision’ in reviewing medical evidence at trial for palpable and overriding error.”

[72] Wagner J. (as he then was) concluded, at para. 86:

It could be said that it would have been open to the trial judge to find in favour of the plaintiff, particularly if individual components of the evidence had been examined in isolation. However, the trial judge carefully weighed the evidence as a whole, including both the statistical evidence and the evidence specific to Mr. Émond. Against that backdrop, she considered and evaluated three expert opinions, all of which necessarily involved some speculation. Her causation analysis was based on all of this evidence. She made no palpable and overriding error in finding that the plaintiff had failed to establish causation on a balance of probabilities, and deference to her conclusion is in order.

[73] In my respectful view, the Supreme Court’s caution against the risk of “tunnel vision” should be kept in mind when we are invited to review a fact-laden decision under the rubric of “misapprehension of the evidence”. The focus on individual “misapprehensions” or even individual errors in the assessment of evidence may tend to exaggerate the significance of the disputed finding of fact and divert attention from the trial judge’s assessment of the entirety of the evidence. Bearing this in mind, I turn to the appellant’s submissions concerning the alleged errors in the trial judge’s analysis of factual causation.

(a) First branch: Did the trial judge err in finding uLMS was likely present in May 2009?

[74] Dr. Browning and Dr. Covens testified that uLMS was likely present on May 25, 2009 when the appellant first examined Ms. Hacopian-Armen. Dr. Browning opined that the uLMS was likely in or near the endometrium and was likely the cause of her AUB. He testified that because such tumours do not grow “overnight”, and the fact that it was present and in Stage IV when it was discovered in April 2011, made it reasonable to conclude that it was present and in an early stage (Stage I) in May 2009. Dr. Covens’s opinion was similar.

[75] The trial judge accepted this evidence, and concluded “[b]ased on all of the evidence before this court, I accept the evidence of the plaintiff’s experts that the LMS, which was found to have metastasized to Stage IV by April 7, 2011, would have been at Stage I in and around May 25, 2009.”

[76] The appellant’s argument that the trial judge erred in finding that uLMS was likely present in May 2009 rests on three foundations, which I will address in turn, setting out my conclusion in the applicable heading.

(i) The trial judge did not err in admitting the evidence of Dr. Covens on this issue and, having admitted his evidence, did not misapprehend it

[77] At trial, the appellant sought to limit Dr. Covens’s evidence regarding factual causation on the ground that he had failed to provide the foundational basis for his opinion in his expert report, filed pursuant to r. 53.03 of the Rules of Civil Procedure, R.R.O. 1990, Reg. 194.

[78] Rule 53.03 requires a party intending to call an expert witness at trial to serve the expert’s report at least 90 days before the pre-trial conference. The purpose of r. 53.03 is to avoid surprise at trial, to enable counsel to prepare to challenge the opinion and to allow for efficiency in preparation and trial.

[79] The expert’s report is required to contain certain information set out in r. 53.03(2.1), including the expert’s opinion concerning each issue to which the report relates and the expert’s reasons for their opinion. It must include the factual assumptions on which the opinion is based, any research conducted by the expert and any documents relied on by the expert in forming the opinion. It is well-settled that the report must not simply set out the expert’s conclusions, but must also set out reasons for their opinion: Marchand (Litigation guardian of) v. Public General Hospital Society of Chatham, at para. 38, leave to appeal refused [2001] S.C.C.A. No. 66; Hoang v. Vicentini, 2012 ONSC 1358, aff’d 2016 ONCA 723, at para. 10.

[80] The relevant portion of Dr. Covens’s report was as follows:

Ms. Hacopian-Armen was noted to have lung metastases on CT scan in February 2011. It is impossible to be 100% certain when this malignancy developed, but I do note that she developed a de novo DVT [deep vein thrombosis] in her left calf on August 16, 2010 and a recurrence of it in February 2011, both of which are very suspicious for an underlying malignancy (malignancy disposes patients to DVT’s). With no precipitating events (Danazol is not associated with DVT and she took Ovral for only 2 days in August 2010), for her DVT and the fact she was diagnosed with metastatic disease six months later, I am fairly certain that she had her malignancy in August 2010. Furthermore, I think it likely that it was present prior to that, including at her first visit with Dr. Mahmoud in May 2009. [Emphasis added.]

[81] The appellant argued that the report was deficient, because, although Dr. Covens explained why he believed the tumour was present in August 2010, he failed to explain the basis for his opinion that uLMS was present in May 2009. He argued that the first three sentences of the above extract provided the foundational basis for Dr. Covens’s opinion that the malignancy was present in 2010, but had nothing to do with the separate issue of whether it had been present in May 2009.

[82] The respondent, however, contended that the basis of that opinion was set out in the report: reasoning backward from the fact that Ms. Hacopian-Armen died in August 2011 from a metastatic cancer discovered in 2011, and that she had symptoms of malignancy in August 2010, it was likely that she had the disease in May 2009.

[83] The trial judge accepted the respondents’ interpretation of the report. The malignancy was probably present in May 2009 – because of the presence of DVT in August 2010 and the fact that the cancer had metastasized by February 2011. She found that if there was a different interpretation, as advanced by the appellant, it would be for Dr. Covens to explain on examination.

[84] When Dr. Covens testified, he was clear that in his opinion it would take a considerable time for the cancer to reach the point of metastasizing. Extrapolating back from its condition in 2011, it was likely present in May 2009. He observed that there has been little study of the growth pattern of such tumours, because they are typically discovered after the uterus has been surgically removed due to malignancy or abnormality.

[85] I see no error in the trial judge’s decision to permit Dr. Covens to testify on this issue. Her interpretation of the report was reasonable and consistent with the opinion given in Dr. Covens’s testimony. It was obvious that the timing of the origin of the malignancy was a central issue at trial and the appellant adduced expert evidence on that very question. As a result, the appellant could not have been taken by surprise by Dr. Covens’s evidence. The appellant demonstrated no prejudice as a result of misunderstanding Dr. Covens’s report.

[86] Nor do I accept the appellant’s submission that the trial judge misapprehended Dr. Covens’s evidence when she stated that it was his opinion that it was “highly likely” that Ms. Hacopian-Armen had Stage I uLMS in May 2009. That was in fact Dr. Covens’s opinion, based on the facts set out in his report and his experience with uterine cancers.

(ii) The trial judge did not misapprehend Dr. Browning’s evidence

[87] In his factum, the appellant asserted that the trial judge misapprehended the evidence of Dr. Browning when she said that, “[Dr. Browning] stated that [uLMS] does not occur overnight and that in May 2009, it was likely at Stage I, given the progression by April 2011” and that Ms. Hacopian-Armen was “likely suffering from a malignancy on May 25, 2009 which caused the abnormal bleeding.”

[88] There was no misapprehension. Dr. Browning’s testimony was that there was a “very good chance” that her abnormal bleeding in 2009 was due to the uLMS and that it was “more likely than not” that an endometrial biopsy performed on May 25, 2009 would have detected uLMS.

[89] The appellant did not pursue this issue in oral argument. I would reject this ground of appeal.

(iii) The trial judge did not misapprehend the evidence of the defence expert, Dr. Vilos

[90] The appellant submits that the trial judge misapprehended Dr. Vilos’s evidence when she stated at para 152: “The defendants submit that there is no proof that [uLMS] was present on May 25, 2009 when an endometrial biopsy should have been performed. They, therefore, argue that there is no evidence which would establish a link of causation necessary for this case.” The appellant says that this misstated his case. He did not contend there was an absence of evidence. Instead, he contended that there was affirmative evidence of Dr. Vilos, based on Ms. Hacopian-Armen’s clinical history – the absence of rapidly growing tumours and what he described as bleeding that tracked her menstrual cycle – which established that uLMS was not present in May 2009. This misapprehension of Dr. Vilos’s evidence, he contends, was a reversible error.

[91] I do not agree that the trial judge misapprehended Dr. Vilos’s evidence. She adverted, correctly, to his testimony that an endometrial biopsy performed on May 25, 2009 would not have been positive because “there is no evidence that a leiomyosarcoma, in my opinion, was there at this time.” She also referred to his opinion that Ms. Hacopian-Armen had “regular bleeding” at the time. In my view, the trial judge’s rejection of Dr. Vilos’s evidence was not the result of a misapprehension of his evidence. It was simply the result of her acceptance of the evidence of the respondents’ experts in preference to that of Dr. Vilos.

[92] Finally, although it is not raised as a discrete ground of appeal, the appellant is critical of the trial judge’s reference to the principle expressed in Goodwin v. Olupona, 2013 ONCA 259, 305 O.A.C. 245. At paras. 152-54, the trial judge observed:

The defendants submit that there is no proof that LMS was present on May 25, 2009 when an endometrial biopsy should have been performed. They, therefore, argue that there is no evidence which would establish a link of causation necessary for this case.

The reason that there is no evidence is attributable to the fact that Dr. Mahmoud did not perform an endometrial biopsy which would have provided the necessary evidence.

As stated above, where there is a gap in the evidence as regards establishment of causation which is caused by the defendant's own negligence, this cannot be used to shield the defendant from any responsibility. The inability to prove the causal link between the defendant's negligence and the plaintiff's damages, if a direct result of the defendant's failure to act appropriately, cannot be used to shield the defendant: Goodwin (Litigation Guardian of) v. Olupona, supra, Ghiassi v. Singh, supra, Adams v. Taylor, supra.

[93] I am not satisfied that the principle expressed in Goodwin, at paras. 72-74 and in Ghiassi v. Singh, 2018 ONCA 764, at para. 29 has any application to a case such as this, where both parties adduced evidence on the issue of causation. I accept the respondents’ submission, however, that the reference to this principle was unnecessary as the trial judge independently accepted the evidence of the respondents’ expert witnesses that Ms. Hacopian-Armen’s cancer was probably at Stage I in May 2009.

[94] For these reasons, I would not give effect to this ground of appeal.

(b) Second branch: Did the trial judge err in finding that an endometrial biopsy would likely have detected uLMS, had it been present?

[95] Before addressing this branch of the appellant’s submissions, I observe that the appellant does not challenge the trial judge’s findings that (a) Dr. Mahmoud breached the standard of care in failing to perform a routine biopsy that was capable of identifying uterine malignancies, including uLMS; (b) the biopsy should have been performed because Ms. Hacopian-Armen was at risk for uterine malignancies because of her age, her AUB and her nulliparous state; and (c) had she been diagnosed with uLMS on May 25, 2009, her outcome would have been substantially improved.

[96] In coming to these conclusions, the trial judge accepted the evidence of Dr. Covens and Dr. Browning, and rejected the evidence of the appellant’s experts.

[97] As I have rejected the first ground of appeal, in which the appellant asserted that the trial judge erred in concluding that the uLMS was present in May 2009, the remaining issue is the appellant’s assertion that the trial judge erred in concluding that the endometrial biopsy would probably have detected the uLMS. The appellant alleges that the trial judge misapprehended the evidence, including aspects of the evidence of the appellant’s experts. These submissions focus on one paragraph of the trial judge’s reasons, para. 144, which I set out in full for reference:

It is the evidence of the defendant's experts that the likelihood of having found LMS at the first consult in May 2009 is purely speculative and unknowable. The defence argued that there was no evidence of any LMS having broken through the myometrial/endometrial lining into the uterine cavity based on all of the imaging. They contended throughout that LMS could not be detected unless it were in the uterine cavity. The plaintiff's experts refute this position. I note as well that the endometrial biopsy finally undertaken on April 7, 2011 did detect the sarcoma, although the LMS had not yet entered the uterine cavity. The defendant further maintained that the plaintiff was clearly pre-menopausal such that sensitivity of detection would be under 50%. While there were no fibroids seen in the uterine cavity on imaging, this does not exclude the likelihood that LMS, was in or near the endometrium, causing or contributing to the abnormal bleeding while it was still undetectable by diagnostic imaging. The evidence at trial indicated that the diagnostic imaging would not detect a LMS and that 95% of LMS malignancies originate de novo and are not part of an existing fibroid. It is of note that the endometrial biopsy conducted in April 2011 did diagnose the presence of a LMS at a time when the plaintiff was still, according to the defendants, “pre-menopausal” as opposed to “peri-menopausal”, and at a time when the LMS was not in the uterine cavity. Further, there was no evidence of uterine invasion of the LMS on any kind of diagnostic imaging at that time. This is contrary to the defence theory of the case which suggests that in the circumstances described, the biopsy should have been negative. I should add that I do not find this fact determinative of whether there was LMS present on May 25, 2009. In that regard, I have based my findings on other evidence, without using a retrospective analysis.

[98] With that background, I turn to the alleged errors, again summarizing my conclusions in the applicable heading.

(i) The trial judge did not misapprehend the appellant’s experts’ evidence on the likelihood of detection of uLMS

[99] The appellant submits that the trial judge misapprehended the appellant’s experts’ position, when she stated that they testified that the likelihood of having found LMS in May 2009 was “purely speculative and unknowable”. The appellant submits that this was a misapprehension because the appellant led affirmative evidence that even if uLMS was present in May 2009, it was unlikely that an endometrial biopsy would have diagnosed it, given the poor sensitivity of the test and the fact that the uLMS was not likely in a location that was amenable to sampling.

[100] I begin by observing that the appellant’s expert, Dr. Vilos, testified that there was “no evidence” that uLMS was present at the time and “no evidence” that the uLMS had moved into the uterine cavity where, in his opinion, the cancer had to be located in order to be detected by an endometrial biopsy. As the trial judge correctly noted, it was Dr. Vilos’s evidence that the uLMS would have had to have broken through the myometrium/endometrium and into the uterine cavity to be detected.

[101] The trial judge did not overlook or misapprehend the appellant’s evidence. The appellant is correct to point out that Dr. Vilos’s position on the likelihood of finding uLMS in 2009 was not that it was “purely speculative and unknowable”, but rather that it was unlikely to have been detected. However, the trial judge correctly referred to Dr. Vilos’s evidence a number of times, at paras. 48 and 52. The trial judge’s characterization of his evidence, at para. 144, was not central to her conclusion. Again, she simply accepted the evidence of the respondents’ experts, who disagreed with Dr. Vilos’s evidence. They testified that Ms. Hacopian-Armen was closer to being menopausal than pre-menopausal and that this status increased the sensitivity of the endometrial biopsy and made detection of uLMS more likely than not. Further, the trial judge found, at para. 70, that the studies relied on by the appellant on the correlation between the location of the LMS and its detectability by a biopsy were unreliable and inconclusive.

(ii) The trial judge did not misapprehend the appellant’s experts’ evidence on the location of uLMS

[102] The appellant submits that the trial judge misapprehended the evidence of the defence experts, when she stated, at paras. 48, 53, and 58, that Dr. Vilos and Dr. Leyland had testified that the uLMS had to be in the “uterine cavity” to be detected by an endometrial biopsy. The appellant asserts that his experts’ evidence throughout trial was that the cancer had to be in a location such as the uterine cavity or just underneath the endometrium, so as to be amenable to sampling by endometrial biopsy which, as the name suggests, is a sampling of the endometrium.

[103] I would not accept this submission. On numerous occasions, the appellant’s experts testified that the uLMS had to be in the uterine cavity to be detected. In his examination-in-chief, Dr. Vilos was asked the following questions and gave the following answers:

Q. And so I understand that's your view on whether or not the cancer was present. I want you to assume for the time being that the cancer was there in May 2009, and when I mean the cancer, I mean the uterine leiomyosarcoma. Assuming the uterine leiomyosarcoma was present in May 2009, Dr. Vilos, would an endometrial biopsy have diagnosed it in any event?

A. No.

Q. And why not?

A. For the biopsy to pick up a leiomyosarcoma, the leiomyosarcoma – remember, its genesis is in the wall of the uterus. For it to be picked up, it would have to move inside the uterine cavity, and we have no evidence here that the – the ultrasound, that it had moved into the uterine cavity. And the other evidence comes from the literature, multiple papers where they say that the sensitivity of endometrial biopsy, it's very low in the presence of leiomyosarcoma, picking up a leiomyosarcoma. [Emphasis added].

[104] And again, later in his evidence:

Q. And what, if anything, is the significance of this to your opinion?

A. It's pretty much what I said. For the leiomyosarcoma to be picked up by endometrial biopsy, it has to be sticken [sic] inside the uterine cavity.

Q. And based on the imaging we looked at all the way to December 2009, were there any masses reported to be invading the endometrium or uterine cavity?

A. Not according to any of the ultrasounds. [Emphasis added].

[105] Similarly, Dr. Leyland testified in cross-examination:

Q. But if I understood your evidence, you said that the tumour has to be in the endometrial cavity in order for the biopsy to be successful. Is that right?

A. Yes.

Q. And if it's not in the, if it's not in the uterine cavity the, the biopsy will not work.

A. Yes. [Emphasis added].

[106] In contrast to this evidence, the respondents’ expert, Dr. Covens, testified that the uLMS did not have to be in the uterine cavity to be detected by an endometrial biopsy. He stated, however, in his evidence-in-chief that “obviously the closer [the tumour] is to the uterine cavity, the higher the likelihood one is going to pick it up on a biopsy.”

[107] Dr. Covens also explained his disagreement with Dr. Vilos in his examination-in-chief:

A. [H]ow does an endometrial biopsy identify a leiomyosarcoma? Clearly, if there's invasion into the endometrial tissue that's one possibility.

Q. Mm-hmm.

A. Second of all, if you've got a deep biopsy that, biopsies not only in the endometrium but that tissue underlying the endometrium, the myometrium, that can pick it up, as well. And thirdly, if you've got a leiomyosarcoma that is what we call a submucosal where it starts impinging, outgrowing towards the uterine cavity, which fibroids can do, as well, that can denude the endometrial lining and you can just biopsy that mass. So, so that's all the endometrial biopsy would indicate from a patient with a leiomyosarcoma.

[108] I am not satisfied that the trial judge misapprehended the evidence of the appellant’s experts on this issue. There was a clear conflict in the expert evidence as to whether an endometrial biopsy could detect a cancer that was not in either the uterine cavity or the endometrium. The trial judge was entitled to prefer the evidence of the respondents’ experts on this issue.

[109] As noted earlier, there was another aspect of the evidence, hotly contested by the appellant at trial, as to whether Ms. Hacopian-Armen was likely close to menopause, making it more likely that an endometrial biopsy would detect her uLMS. The trial judge found:

While the defendants relied heavily on certain studies which indicated, inter alia, that in pre-menopausal women, an endometrial biopsy has a lower percentage likelihood of detection of LMS, Dr. Browning testified that women who are nulliparous have a 13 times more likely chance of having early menopause; that women 40 to 49 years of age have a greater differentiation in their production of hormones in comparison with 20-29, and 30-39 age ranges and stated that there was evidence to suggest that the plaintiff was beginning to have changes which would make her hormonally closer to menopause than pre-menopause, or what he indicated as "peri-menopausal". It was a laboratory report during that time which indicated her to be "peri-menopausal" or "peri". Her FSH levels were rising, which was also a sign that her body was hormonally moving toward menopause. Therefore, even based on the studies relied on by the defendant, there was a greater likelihood that LMS would have been detected in the plaintiff.

[110] In sum, I am not satisfied that the trial judge misapprehended the evidence on this issue or made either a “palpable” or “overriding” error in her assessment of the evidence. She simply preferred the respondents’ experts’ evidence that Ms. Hacopian-Armen’s menopausal or peri-menopausal status was a better indicator of whether an endometrial biopsy would have detected uLMS in 2009 than the location of the LMS. I would not give effect to this ground of appeal.

(iii) The trial judge did not misapprehend the nature and significance of the diagnostic imaging evidence

[111] The appellant submits that the trial judge misapprehended the evidence concerning the capabilities of diagnostic imaging. He asserts there was no evidence to support the trial judge’s conclusion that uLMS could have been in or near the endometrium while it was still undetectable by diagnostic imaging. Further, he submits the imaging from 2009 did not show any masses in or near the uterine cavity, which reduced the likelihood of detection by endometrial biopsy.

[112] I begin by setting out the relevant portion of the reasons for judgment, reproduced in full earlier:

The defence argued that there was no evidence of any LMS having broken through the myometrial/endometrial lining into the uterine cavity based on all of the imaging. … While there were no fibroids seen in the uterine cavity on imaging, this does not exclude the likelihood that LMS, was in or near the endometrium, causing or contributing to the abnormal bleeding while it was still undetectable by diagnostic imaging. The evidence at trial indicated that the diagnostic imaging would not detect a LMS and that 95% of LMS malignancies originate de novo and are not part of an existing fibroid.

[113] The appellant submits that “[o]n the correct evidence, there is no scenario in which uLMS would be in the uterine cavity or submucosal (i.e. near the endometrium) but not appear on imaging.” His position at trial was that because uLMS did not show up on Ms. Hacopian-Armen’s ultrasounds taken prior to and after May 2009, it was not present in the uterus and obviously could not have been detected by an endometrial biopsy.

[114] The problem with this submission is that it does not accord with the evidence of Dr. Covens, which the trial judge accepted.

[115] To begin with, it was common ground that it was impossible to distinguish between fibroids and uLMS by imaging. Dr. Browning testified that they could only be distinguished at the microscopic level. Dr. Covens opined that she “in all likelihood … did have her sarcoma in 2009, albeit small.” He testified that the cancer “originates at the cellular level” and grows from there. However, Dr. Covens noted that even though it might grow to a “mass, a tumour, a bump” that can be visualized, “we don’t have any really good detection methods of separating fibroids from leiomyosarcoma.” On cross-examination, he agreed with the observation that in order to be visible on imaging, the cancer has to grow to a size in which it can be observed on radiology. He also stated that at an early stage, the tumour may have been “undetectable from an ultrasound point of view where it might have been detectable by pathology [i.e., a biopsy].”

[116] Dr. Covens also noted that Ms. Hacopian-Armen had declined to have a pelvic transvaginal ultrasound, which he described as the “gold standard test to interpret endometrial, myometrial pathology.” When it was put to Dr. Covens that up to December 2009 there was no imaging report of any submucosal or intracavity fibroid, he responded, “[y]es, but she didn’t have a transvaginal ultrasound so that might have been somewhat difficult to identify.”

[117] I conclude that the trial judge did not misapprehend the evidence on this issue. She simply accepted Dr. Covens’s evidence that the tumour was not visible on imaging because it was very small or because it was only detectable by a pelvic transvaginal ultrasound and that did not take place until April 2011, when her cancer was well advanced.

(iv) The trial judge did not err in asserting that the uLMS had not yet entered the uterine cavity in April 2011 and the trial judge did not improperly rely on the April 2011 endometrial biopsy that detected the uLMS

[118] The appellant’s last two submissions on this issue can be addressed together. First, the appellant submits that the trial judge misapprehended the implications of the endometrial biopsy that diagnosed Ms. Hacopian-Armen’s uLMS in April 2011. He submits the trial judge misapprehended the evidence when she stated that the tumour had not invaded the uterine cavity in April 2011 when the endometrial biopsy was performed, and subsequently used her erroneous assessment of the evidence to reject the defence submission that uLMS has to be in a location amenable to an endometrial biopsy for a diagnosis to be made. The appellant submits that the 2011 biopsy supported the defence theory that location of the tumour is critical to diagnostic sensitivity, and that the absence of masses in or near the uterine cavity in 2009 made it unlikely that an endometrial biopsy would have detected the cancer.

[119] The appellant’s second submission is that the trial judge erred in relying on the 2011 endometrial biopsy altogether because Ms. Hacopian-Armen demonstrated a dramatically different clinical picture in 2011 as opposed to 2009, and the results of the 2011 biopsy were of no value in assessing her condition in 2009.

[120] The appellant’s submissions on this issue omit reference to the full scope of the trial judge’s reasoning, in which she made it clear that the detection of uLMS by endometrial biopsy in 2011 was not central to her findings about Ms. Hacopian-Armen’s condition in 2009. At para. 144, she said:

It is of note that the endometrial biopsy conducted in April 2011 did diagnose the presence of a LMS at a time when the plaintiff was still, according to the defendants, “pre-menopausal” as opposed to “peri-menopausal”, and at a time when the LMS was not in the uterine cavity. Further, there was no evidence of uterine invasion of the LMS on any kind of diagnostic imaging at that time. This is contrary to the defence theory of the case which suggests that in the circumstances described, the biopsy should have been negative. I should add that I do not find this fact determinative of whether there was LMS present on May 25, 2009. In that regard, I have based my findings on other evidence, without using a retrospective analysis. [Emphasis added.]

[121] Further, the question of whether the uLMS had invaded the uterine cavity by 2011 was contested at trial. It was open to the trial judge to note that the defence’s theory was potentially undermined if the uLMS was detected by an endometrial biopsy in spite of being outside the uterine cavity. Ultimately, it did not matter, because the trial judge based her findings on the respondents’ experts’ theory that Ms. Hacopian-Armen’s menopausal status, among other things, would have made detection of the uLMS by endometrial biopsy more likely than not.

[122] I am not persuaded that the trial judge erred in her assessment of the evidence in relation to the 2011 biopsy.

[123] I would therefore reject this ground of appeal.

F. Disposition

[124] For these reasons, I would dismiss the appeal.

[125] The parties advised that they expected to agree on costs. If they have been unable to do so, they may make written submissions. The respondents shall serve and file their submissions within ten days of the release of these reasons and the appellant shall have ten days within which to serve and file responding submissions. The submissions shall not exceed three pages, excluding costs outlines.

Released: July 29, 2021 “G.R.S.” “George R. Strathy C.J.O.” “I agree. K. Feldman J.A.” “I agree. Sossin J.A.”