Fibroids in pregnancy; meaning and management
Women with uterine fibroids are more likely have pregnancies complicated by fetal malpresentation, preterm birth, preterm premature rupture of membranes (PPROM), placenta previa, placental abruption, cesarean delivery, and severe postpartum hemorrhage.
Diagnosis/definition: Uterine fibroids are the most common benign gynecologic tumors
Epidemiology/Incidence: Fibroids are found in 1% to 10% (often 3%) of women during prenatal ultrasound screening.
Risk factors/associations: Pregnant women with fibroids are an on average older, more likely to be African American, and more likely to have additional co-morbid medical conditions (eg, higher body mass index, diabetes, and chronic hypertension), compared to pregnant women without fibroids.
Complications: Women with uterine fibroids are more likely have pregnancies complicated by fetal malpresentation, preterm birth, preterm premature rupture of membranes (PPROM), placenta previa, placental abruption, cesarean delivery, and severe postpartum hemorrhage. The Table summarizes the rates of these outcomes for 2 large recent cohorts. In addition, neonatal birth weight at delivery was lower.The majority of women with fibroids have only one fibroid on ultrasound imaging, but up to 22% will have 4 or more fibroids. Peripartum outcomes do not differ for women with one or multiple fibroids (Table). The location of the fibroid also does not influence obstetric outcomes.
- Preconception/Prenatal counseling: Women should be counseled that the risks of obstetrical complications are increased with the presence of fibroids in pregnancy, but neither size or location adequately predict additional adverse outcomes. Most fibroid growth occurs in the first trimester. Throughout pregnancy approximately 60% of fibroids will increase or decrease by greater than 10% of their original size.
- Prenatal care: Fibroid-related pain requiring medications occurs in 5%–15% of women with fibroids. Use of nonsteroidal anti-inflammatory analgesic medications may be required and indomethacin (25 mg–50 mg by mouth every 6 hours for up to 48 hours) is a treatment option. Pain that does not improve within 48 hours of medical treatment should prompt the clinician to search for alternative etiologies. Prostaglandin synthase inhibitors should generally be avoided beyond 32 weeks’ gestation or restricted for use to fewer than 48 hours due to potential for fetal complications such as oligohydramnios and premature constriction of the ductus arteriosus. One of the primary concerns regarding risks associated with prior myomectomy is uterine rupture either before or during labor. When evaluating the risk of uterine rupture, the extent of the uterine incision(s) as well as the size and number of myomas removed should be considered. In a report of 412 women with a pregnancy after myomectomy at a teaching institution in Nigeria, the incidence of uterine rupture was 0.2%.
- Delivery: In women with prior myomectomy, a plan for labor and vaginal delivery is reasonable in those who did not have extensive myometrial dissection or entry into the endometrial cavity. Alternately, for those who choose an approach for scheduled cesarean delivery, timing at 37–38 weeks’ gestation is reasonable
- Postpartum/breastfeeding: 36% of fibroids that presented in early pregnancy resolve and another 76% will have reduced in size by the postpartum period.