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.