Interpretation
Previous studies have also reported increased adverse pregnancy outcomes, including abnormal placentation, such as placenta previa or placenta accreta,10-12 preterm delivery, cesarean delivery, uterine rupture, and postpartum bleeding, in women with a history of myomectomy.13-16 The true incidence of uterine rupture during subsequent pregnancy following myomectomy is difficult to establish, because most of the studies have been cases, case series, or small retrospective cohort studies that do not account for the total number of pregnancies achieved after myomectomy and their consequent outcomes. The incidences of preterm birth and uterine rupture after myomectomy have been variously reported to range from 3.1% to 35% and from 0.2 to 3.7%, respectively.17, 18 The previous systematic review including all cohort studies with at least five cases demonstrated that the overall incidence of uterine rupture after myomectomy was 0.93% (0.45–1.92%) (n = 7/756); specifically, it was 0.47% (0.13–1.70%) (n = 2/426) in women undergoing a trial of labor after myomectomy, and 1.52% (0.65–3.51%) (n = 5/330) in women before the onset of labor.5 However, the number of pregnancies and viable deliveries after prior myomectomy were 2,367 and 1,284, respectively, from a total of 23 studies. In our study, pregnancy outcomes were available for 9,890 women with a history of myomectomy, which was the largest population. In the previous studies, although uterine rupture occurred at various gestation, it occurred more often before the onset of labor, with a high rate of fetal loss.18.5 In this study, the incidence of uterine rupture in women with a history of myomectomy was 0.22%, which is less than the reported incidence of uterine rupture (0.4-0.7%) in a trial of labor after cesarean section.19,20 Possible reasons can be a missing diagnosis when uterine rupture is combined with abruptio placenta or antepartum/postpartum bleeding in the middle of pregnancy. Also, uterine dehiscence can be underdiagnosed, based on the data from diagnostic code. However, in this study, women with a history of myomectomy had more than a 12-fold risk of uterine rupture over that of women without a diagnosed myoma. Therefore, counseling for myomectomy in women who desire a pregnancy in the future should discuss the risk of adverse pregnancy outcomes, especially uterine rupture during pregnancy, which can be associated with fetal loss.
In a previous comparison study about delivery outcomes between pregnancies following myomectomy and myoma-complicated pregnancies, the latter showed better outcomes, including fewer cesarean sections, preterm births, and less blood loss, than did pregnancies after myomectomy, which were similar to the results of this study21 A prospective, randomized, multicenter study in couples with unexplained infertility demonstrated no significant difference in conception, placenta previa, preterm labor, postpartum hemorrhage, or live birth rates in women with non-cavity distorting myomas and those without myomas.22 A recent retrospective cohort study23 revealed that women with a history of myomectomy were associated with a 180% increased risk of intraoperative transfusion, were 713% more likely to experience a bowel injury, and were 243% more likely to undergo a cesarean hysterectomy. These findings provide reassurance that pregnancy success is not affected in couples with non-cavity distorting myomas undergoing assisted reproductive treatment (ART) for unexplained infertility.
Previously, ACOG stated that myomectomy should be considered for a woman with uterine leiomyomas who has undergone several unsuccessful IVF cycles despite appropriate ovarian response and good-quality embryos.24 SOGC, ASRM, and French guideline also stated that intramural myomas may have a negative effect on fertility, but treating them does not improve fertility, and myomectomy is therefore indicated only for symptomatic myomas,8,24,25 They emphasized that information should be provided about the risk of uterine rupture during a future pregnancy, before planning a myomectomy in women who might become pregnant later on.