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Tanos et al. Mini-invasive Surg 2020;4:39 I http://dx.doi.org/10.20517/2574-1225.2019.59 Page 7 of 15

Cons of surgical removal of endometriomas
The total patient population of articles providing evidence against the benefit of endometrioma surgery
before ART was 9983. Table 2 summarizes the “cons” of surgical removal of endometriomas prior to IVF
according to current evidence.

Evidence that surgical removal of endometriomas damages ovarian reserve and function - reduced
ovarian reserve, increased gonadotropin stimulation, lower embryo transfer, implantation and pregnancy
rates, increased risk of cycle cancellation - was provided by 16 articles, with a total patient population of
9603. Eight studies provided evidence that surgical removal of endometriomas negatively affects ovarian
reserve. These eight studies included a mix of retrospective [15,25] , prospective [26,27] , meta-analysis/systematic
[8]
review [10,28,29] and the Royal College of Obstetricians and Gynaecologists scientific impact paper . Among
1642 women with infertility across three age groups (< 30, 31-35, < 36), there was a lower anti-Mullerian
hormone (AMH) in patients with previous endometrioma cystectomy (1.23 +/- 0.15) as compared to
patients with endometriomas > 3 cm (2.22 +/- 0.23) and patients with non-endometrioma causes of
[25]
infertility (3.08 +/- 0.1) (P < 0.0001) . In the retrospective case-control of 428 women undergoing IVF, of
which 142 had in situ endometrioma at the time of IVF, 112 had laparoscopic endometrioma cystectomy
pre-IVF and 174 women had tubal infertility, there were higher cycle cancellation rates in the cystectomy
group (7.5% in endometrioma in situ, 9.8% in surgery, 2.9% in tubal factor; P < 0.02) . Among 237 patients
[15]
who were treated for endometriomas via cystectomy, there was a statistically significant decrease in AMH
after surgery (mean difference: -1.13 ng/mL; 95%CI: -0.37 to -1.88) . Another study of 193 patients with
[28]
endometriomas undergoing laparoscopic cystectomy showed that the surgical removal of endometrioma
results in reduced ovarian reserve (pre-operative AMH was 3.86 +/- 3.58; average post-operative AMH by 9
[30]
months was 1.83 +/- 2.06; P < 0.001) .
Two studies, with a combined total patient population of 385 women with endometriomas showed that
excision may remove healthy ovarian tissue. According to a histological analysis of endometrioma tissue
from 59 patients, endometriotic tissue can cover up to 98% of the entire cyst wall (median of 60%) and
[31]
reach up to 2 mm in depth . Furthermore, proportionally more endometrioma cystectomies disclosed
[32]
ovarian stroma vs. dermoid cystectomies (80.3% and 17.2%, respectively; P < 0.001) . Since their study
found higher implantation (28% and 19%, respectively; P = 0.02) and embryo transfer rates (79.7% and
[9]
70.7%, respectively; P = 0.03) in women with simple cysts vs. endometrioma, Kumbak et al. proposed
that poorer IVF outcomes due to the presence of endometriotic cysts during IVF may be attributable
to the disease itself, rather than the cystic mass. Higher doses of gonadotrophin may be required for
ovarian stimulation in patients with endometriomas surgically removed pre-IVF vs. patients with intact
[8]
endometriomas . This is supported by data from the RCT of 99 patients with endometriomas, which found
that those who had endometriomas surgically removed pre-IVF required more days of stimulation (14.0
[23]
+/- 2.5, P < 0.001) as compared with those who went directly to IVF (10.8 +/- 2.6, P < 0.001) . A recent
retrospective study investigated ART outcomes in endometriomas vs. other types of endometriosis and
found that previous endometrioma removal surgery was independently associated with lower pregnancy
[33]
rates with ART multivariate analysis OR: 0.39 (0.18-0.89; P = 0.16) .

Limited benefit of surgery - based on ovarian responsiveness, oocyte quality and endometrial receptivity -
was reported by four articles with a combined total patient population of 375. A recent prospective study
of women with unilateral endometriomas found no difference in: (1) ovarian responsiveness (3.7 +/- 2.4
and 4.1 +/- 1.7; P = 0.54), (2) number of suitable oocytes (3.1 +/- 2.6 and 3.5 +/- 2.3; P = 0.51), (3) number
of ‘high quality’ embryos (1.8 +/- 2.1 and 1.8 +/- 1.4; P = 0.00) and (4) fertilization rate (64% and 64%, P
[34]
= 0.96) between the affected vs. intact ovary, respectively . Additionally, one literature review concluded
[35]
that despite often lower numbers of oocytes retrieved, oocyte quality remains the same after surgery .
Finally, one prospective cohort study of 103 patients proposed that endometrial receptivity and accessibility