Unexpected coexistent endometriosis in women with symptomatic uterine leiomyomas is independently associated with infertility, nulliparity and minor myoma size

PURPOSE: To determine risk factors for unexpected coexistent endometriosis in laparoscopic myomectomy for symptomatic uterine leiomyomas. METHODS: This was a single-centre, retrospective cohort study conducted at a University Women's Hospital with a certified endometriosis centre. Data were collected from patients with symptomatic uterine leiomyomas who underwent laparoscopic myomectomy. The main outcome measured in the study was the presence of histologically confirmed endometriosis. Binary regression analysis was used to investigate risk factors for the coexistence of endometriosis. Postoperative complications were classified according to the Clavien-Dindo classification. RESULTS: From 2014 to 2018, 223 patients underwent laparoscopic myomectomy for symptomatic leiomyomas, and 57 (25.6%) had unexpected endometriosis. Women with endometriosis significantly more frequently were nulliparous (66.7% vs. 51.2%; p = 0.04), had reported infertility (31.6% vs. 15.7%; p = 0.01) and smaller leiomyomas (mean diameter 4.92 cm) than women without endometriosis (mean diameter 6.02 cm; p = 0.006). Coexistent endometriosis significantly increased mean operative time (168.4 vs. 142.8 min; p = 0.05) while intra- and postoperative complications showed a similar distribution (p = 0.87) and length of hospital stay (p = 0.26). Binary regression analysis identified 2.3- and 2.2-fold increases in the risk of endometriosis for infertility (p = 0.042) and nulliparity (p = 0.041), respectively. Myoma size influenced the risk of endometriosis by a factor of 0.8 per cm (p = 0.037). CONCLUSIONS: Coexistent endometriosis should be expected in leiomyoma patients particularly with nulliparity, infertility or minor myoma size as independent risk factors. Preoperative counselling should incorporate surgical therapy of coexisting endometriosis.