Spontaneous complete regression of large uterine fibroid after the second vaginal delivery: Case report.

Rationale: Fibroids are common, hormone-dependent, benign uterine tumors. It is estimated that they occur in 20% to 40% of women during their reproductive years. The prevalence of fibroids among pregnant women is 10.7%. Most fibroids do not increase in size during pregnancy. Pregnancy has a variable and unpredictable effect on fibroid growth. The influence of pregnancy on uterine fibroid size still remains unclear. Researchers evaluating fibroids have reported an inverse association between parity and fibroids, suggestive of a protective effect. Pregnancies that occur while fibroids are small would be protective; whereas pregnancies occurring before fibroid development or after the tumors reach some critical size would not be protective. Herein, the case of a woman with a large uterine fibroid that was spontaneously regressed after a second successful vaginal delivery is reported. To our knowledge, the complete regression of a large fibroid after delivery has not yet been reported.

Patient Concerns: A 35-year-old gravida 1 para 0 woman was referred from a private clinic with a history of pelvic mass, adnexal mass and 19 weeks of amenorrhea.

Diagnosis: Ultrasonographic examination indicated a solid mass at the uterine fundus (12.1 × 8.3 cm) suggestive of a uterine fibroid and complex echogenic mass at the right adnexa (7.7 × 6.0 cm).

Interventions: Usually, cesarean sections are performed after myomectomy due to the risk for rupture when attempting vaginal delivery. So, the patient decided against the myomectomy, because she did not have any myoma-related symptoms after the first vaginal delivery and wanted to have more children via vaginal birth.

Outcomes: Six months postpartum she becomes pregnant again. The patient had another vaginal birth. Four years after second delivery, the large myoma completely regressed.

Lessons: Fibroids can regress with postpartum involution. Even though fibroid-related pregnancy complication is 10% to 30%, prophylactic myomectomy is not recommended. In addition, given the protective effect of parity, conception and delivery are reasonable option and could allow treatment to be deferred in women planning a pregnancy.