In a multicenter study in Italy, a similar study design was used to compare the effect of diagnostic laparoscopy with surgical resection and ablation of visible endometriosis (on fertility parameters) in infertile women with minimal to mild endometriosis (192). Eligible patients were less than 36 years old, were trying to conceive, and had a laparoscopically confirmed diagnosis of minimal or mild endometriosis. None of the women had therapy for endometriosis or infertility. Treatment was randomly allocated during laparoscopy. There was a follow-up period of 1 year after the laparoscopy. The results of this study did not show a beneficial effect of surgery regarding fertility. During the follow-up period after laparoscopy, no statistically significant differences in conception and live birth rates were observed in the treated group (24% and 20%, respectively) or in the control group (29% and 22%, respectively). The methodological quality of the Italian study was inferior to the Canadian study, as reviewed before (181,191,192). First, the study was underpowered, including only 91 patients, compared to 341 patients in the Canadian study. Second, it is remarkable and unexplained that the Italian study included after randomization more patients undergoing surgical excision of endometriosis (n = 54) than patients undergoing diagnostic laparoscopy (n = 47). Third, the duration of infertility was longer in the Italian study (4 years) than in the Canadian study (32 months). Duration of infertility is an important factor inﬂuencing both monthly fecundity rate and cumulative pregnancy rates independently from other causes of infertility. The bias introduced by the long duration of infertility in couples participating in the Italian trial may have reduced the possibility to find any significant effect of surgical treatment, especially in view of the lack of proper power calculation in the Italian study. Fourth, the Italian study did not present any data on monthly fecundity rate or cumulative pregnancy rates using life table analysis, but only published the crude live birth rate per patient, not controlled for number of cycles per patient. Fertility outcome should be measured by more controlled variables such as monthly fecundity rate and the cumulative pregnancy rates or time to pregnancy. Fifth, 41 of 91 patients in the Italian study had received GnRH analogue treatment after surgery (18 from the surgical excision group, 23 from the diagnostic laparoscopy group) (192). There was no specification for how long this medical treatment was given and how ovarian function was affected. The lack of this information introduces another bias inﬂuencing fertility outcome. Taking into account the relative methodological weaknesses of the Italian study when compared to the Canadian study, extreme caution is needed before combining these two studies in a meta-analysis, especially because the fertility outcome data are reported so differently. It seems preferable to use the data of the better study demonstrating that surgical treatment of minimal to mild endometriosis appears to offer a small, but significant, benefit with regard to fertility outcome (1,181,191,437). The surgical removal of peritoneal endometriosis may be important to prevent progression of endometriosis. Care is needed to prevent adhesion formation that could result as a consequence of overenthusiastic excision of minimal to mild endometriosis.
Surgery for Moderate to Severe Endometriosis
When endometriosis causes mechanical distortion of the pelvis, surgery should be performed to achieve reconstruction of normal pelvic anatomy. No randomized trials or meta-analyses are available to answer the question of whether surgical excision of moderate to severe endometriosis enhances pregnancy rate (1). Most studies present only crude pregnancy rates without detailed information regarding time of follow-up and are therefore not relevant (1).
Based on three studies, there seems to be a negative correlation between the stage of endometriosis and the spontaneous cumulative pregnancy rate after surgical removal of endometriosis, but statistical significance was reached in only one study (438–440).