Spontaneous rupture of degenerating leiomyoma in the third trimester complicated by preterm delivery and recurrent necrosis requiring interval myomectomy: A case report

Abstract

Uterine leiomyomas are a common benign neoplasm of the female reproductive tract. They are often asymptomatic and can be present during pregnancy without complication. When leiomyomas outgrow their blood supply, the tissue undergoes degeneration. This process is most often seen in pregnancy. A rare complication of this process is spontaneous rupture, which is a surgical emergency often resulting in intra-abdominal leakage, bleeding, and peritonitis. This report describes the case of a 36-year-old White woman (G1P0) at 35 weeks of gestation with a known enlarging anterior fundal leiomyoma with degeneration who presented with worsening abdominal pain and contractions in the setting of gestational diabetes mellitus. Imaging and clinical findings were concerning for rupture of a degenerating fibroid with intra-abdominal fluid leakage. This event resulted in threatened preterm labor. She underwent low transverse cesarean section, resulting in delivery of a viable neonate. Intraoperative findings included a broad-based fundal leiomyoma with a 1.5 cm defect and drainage of degenerative contents. Six months postpartum, the patient had persistent fibroid degeneration requiring robotic-assisted laparoscopic myomectomy. This case highlights the rare but serious complications of leiomyoma rupture in pregnancy and underscores the importance of close monitoring and appropriate surgical intervention for patients with degenerating leiomyomas.

Highlights

• •In the reported case, serial antepartum ultrasound tracked progressive uterine leiomyoma degeneration.
• •The uterine leiomyoma ruptured spontaneously at 35 weeks of gestation.
• •Rupture presented as acute pain, contractions, and uteroplacental insufficiency.
• •Management with Cesarean delivery preceded interval robotic-assisted myomectomy.
• •Case management prioritized maternal and fetal outcomes and fertility preservation.

1. Introduction

Uterine leiomyomas are the most common benign tumors of the female reproductive tract, affecting 20–70% of cisgender women of reproductive age, with a higher prevalence and earlier onset reported among Black women [1]. In pregnancy, leiomyomas are identified in up to 10% of patients, often as an incidental finding on prenatal ultrasonography [2]. Fibroid growth during pregnancy is driven by elevated levels of estrogen and progesterone, which promote smooth muscle proliferation and extracellular matrix deposition in the myometrium [3]. Although benign and often asymptomatic, leiomyomas in pregnancy can be associated with a range of complications. A 2024 meta-analysis [4] estimates that 10–30% of pregnancies with fibroids have complications, including, abdominal pain, degeneration, breech presentation, placental abruption, increased risk of postpartum hemorrhage, and spontaneous abortion [4]. The rare complication of spontaneous rupture of a degenerated fibroid has been reported few times and remains poorly characterized in the literature [5], [6], [7].

Pregnancy is a risk factor for degeneration of fibroids because estrogen and progesterone promote fibroid enlargement. Rapid enlargement may outpace the fibroid's already disorganized vascular supply, predisposing fibroids to ischemia and degeneration. Competition with the enlarging uterus and placenta for uterine blood flow further contributes to this process [3].

This report presents a rare case of spontaneous rupture of a degenerating uterine leiomyoma in the third trimester, complicated by intra-abdominal fluid leakage and threatened preterm labor, with subsequent recurrent degeneration requiring interval myomectomy.

2. Case Presentation

A 36-year-old White woman (G1P0) presented for routine prenatal care at 8 weeks of gestation based on last menstrual period. Medical history was significant for depression, anxiety, and childhood asthma. Past surgical history included laparoscopic appendectomy, breast fibroadenoma excision, cyst removal, and wisdom tooth extraction. Medications included multivitamin, sertraline, and lamotrigine. She denied tobacco or illicit drug use and reported occasional alcohol consumption prior to pregnancy. Routine infection screening was negative, noninvasive prenatal testing was low risk, and she was noted to be non-immune to rubella.

Ultrasound confirmed an intrauterine pregnancy at 8 weeks of gestation. It also identified a large anterior fundal uterine leiomyoma (Fig. 1A). Serial ultrasounds demonstrated progressive enlargement of the fibroid during the first and second trimesters (Fig. 1B), followed by a marked increase in size and concern for degeneration during the third trimester (Fig. 1C and D). The fibroid remained largely asymptomatic throughout most of the pregnancy aside from uterine size greater than dates and intermittent symptoms attributed to mass effect.

Fig. 1.

Serial ultrasonographic evaluation of the anterior fundal uterine leiomyoma throughout pregnancy. (A) Early confirmatory ultrasound demonstrating the leiomyoma measuring 6.75 × 6.5 cm at 8 weeks of gestation. (B) Second-trimester ultrasound demonstrating interval enlargement to 8.6 × 8.3 × 9.9 cm at 19 weeks of gestation. (C) Third-trimester ultrasound demonstrating marked interval growth to 13.7 × 9.2 × 9.0 cm with sonographic features concerning for degeneration at 31 weeks of gestation. (D) Ultrasound at 33 weeks of gestation demonstrating consistent enlargement with sonographic features concerning for degeneration.

The pregnancy was additionally complicated by gestational diabetes mellitus, diagnosed following abnormal glucose tolerance testing at 28 weeks. Despite dietary modifications, the patient demonstrated persistent hyperglycemia and was initiated on metformin at 31 weeks. She transitioned to insulin glargine therapy at 32 weeks and 3 days of gestation, after which appropriate glycemic control was achieved. Tetanus, diphtheria, and acellular pertussis and respiratory syncytial virus vaccinations were given.

At 34 weeks and 6 days of gestation, the patient presented to her weekly appointment with new abdominal pain, which was attributed to degeneration of the enlarging leiomyoma. Nonstress test was reactive, blood pressure was 124/76, and biopsychical profile was 8/8 the following day. Her symptoms were managed conservatively with analgesics, activity modifications, and return precautions.

At 35 weeks and 3 days of gestation, she developed acute worsening of the abdominal pain, with contractions every three minutes. She denied nausea, vomiting, chest pain, dyspnea, focal weakness, and decreased fetal movement. Vital signs were significant for tachycardia to 116 beats per minute; she remained afebrile and normotensive. Fetal monitoring demonstrated a category 1 tracing. Digital cervical examination revealed a closed cervix, 50% effacement, and − 3 station. Bedside ultrasound confirmed a large degenerating leiomyoma, free fluid in the abdomen, and fetus in vertex position. These symptoms raised concern for spontaneous rupture of the leiomyoma with intra-abdominal leakage. Symptoms were initially managed with 0.25 mg terbutaline, 4 mg morphine, oxycodone-acetaminophen 10/325 mg, and one liter bolus of lactated ringers.

During treatment, regular contractions continued and fetal monitoring revealed late decelerations. The patient reported that her pain was becoming increasingly intolerable. She elected to proceed with delivery via low transverse cesarean section. The procedure was complicated by inadequate pain control via spinal anesthesia, and general anesthesia was initiated.

Intraoperatively, a large volume of viscous pale fluid was present within the abdomen. A viable neonate was delivered with Apgar scores of 3, 5, and 8 at 1, 5, and 10 min. Estimated blood loss was 1200 mL. Examination of the uterus revealed an 8–9 cm fundal leiomyoma with a broad base. A1.5 cm defect on the superior aspect drained necrotic tissue and fluid (Fig. 2). Approximately one-third of the fibroid volume was decompressed through expression of necrotic tissue, the defect was closed, and hemostasis was achieved.

Fig. 2.

Gross intraoperative view of leiomyoma. A1.5-cm defect is visible on the superior aspect of the lesion, through which necrotic contents and fluid were draining.

The postoperative course was complicated by ileus, which resolved with conservative management. The patient was discharged on postpartum day 4. The neonate required treatment in the neonatal intensive care unit for respiratory distress and hypoglycemia attributed to maternal gestational diabetes and was discharged on postpartum day 11.

At her two-week post-partum visit, the patient reported recovering well and elected for etonogestrel implant placement until definitive fibroid management. Pelvic MRI was obtained 6 months postpartum and demonstrated a 4.5 × 4.8 cm anterior fundal fibroid with degeneration (Fig. 3). Because she desired future fertility and wished to reduce the risk of recurrent pregnancy complications, she elected to undergo robotic assisted laparoscopic myomectomy.

Fig. 3.

Pelvic MRI at 6 months postpartum showing a 4.5 × 4.8 cm anterior fundal uterine leiomyoma with degenerative changes.

Myomectomy operative findings revealed a solitary subserosal fundal myoma containing a large volume of pale necrotic tissue (Fig. 4). There was no evidence of extension into the endometrial cavity, and the remaining reproductive anatomy was unremarkable aside from a small cesarean scar. The procedure was completed without complication. Necrotic contents were evacuated, and the remaining myoma was excised (Fig. 5). The patient tolerated the procedure well and was discharged the same day. Pathology demonstrated necrotic smooth muscle with no evidence of malignancy. The postoperative course was uncomplicated, and the patient reported significant improvement of symptoms at follow-up.

Fig. 4.

Intraoperative myomectomy findings: subserosal fundal leiomyoma demonstrating a focal capsular defect with extrusion of necrotic tissue.

Fig. 5.

Intraoperative myomectomy findings: Appearance of the lesion following evacuation of necrotic contents and excision of remaining myoma with closure of myometrial defect.

3. Discussion

Degenerating fibroids during pregnancy are often managed conservatively with analgesics and activity modification [8]. Spontaneous rupture of leiomyoma is thought to result from extensive necrosis that weakens the fibroid capsule [9]. Although degenerating fibroids have been associated with preterm delivery, reports of fibroid rupture during pregnancy are rare [10], [11], [12], [13]. Management is not standardized and depends on gestational age, maternal stability, and fetal status. In this case, severe pain, fetal viability, and threat of preterm labor, prompted emergent cesarean delivery.

The relationship between fibroid rupture and preterm labor is multifactorial. Rupture of a degenerating leiomyoma releases necrotic material and inflammatory mediators into the peritoneal cavity, triggering inflammation and increased prostaglandin production, both of which promote uterine contractility and cervical change. One study further proposed activation of the TNF-α pathway and downstream COX-1 and COX-2 inflammatory signaling following fibroid necrosis [14]. In this case, the presence of purulent-appearing intra-abdominal fluid likely contributed to a pro-inflammatory state.

Mechanical factors may also contribute. Large leiomyomas (>5 cm) can cause uterine overdistension and increase intra-abdominal pressure, both of which are associated with increased uterine irritability [2], [12]. Structural disruption following rupture may amplify these effects. Additionally, severe maternal pain and physiologic stress may increase catecholamine levels, which have been implicated in preterm labor [15]. Together, these mechanisms provide a plausible explanation for the threatened preterm labor in this case.

Although intrapartum myomectomy has been reported in selected cases, it is generally reserved for situations in which safe hemostasis is anticipated [16]. In this patient, myomectomy was deferred because of the myoma's size, degenerative changes, rupture, and associated inflammation, which increased concerns for hemorrhage and technical difficulty. Definitive surgical management was postponed until the postpartum period, when improved tissue healing and operative conditions could be expected.

4. Conclusion

Spontaneous rupture of a degenerating uterine leiomyoma in pregnancy is a rare but serious complication that may present as an acute abdomen and require urgent delivery. This case highlights the importance of close surveillance in patients with large or rapidly enlarging fibroids, as well as prompt evaluation of new or worsening abdominal pain in pregnancy. Management should be individualized, balancing maternal and fetal risks while incorporating patient-centered goals, including future fertility and recovery. Postpartum follow-up is essential, as persistent degeneration may necessitate definitive surgical intervention. Early recognition, active management, and alignment with patient reproductive goals are critical to optimizing both acute and long-term outcomes.

Contributors

Natalie B. Graham contributed to conception of the case report, interpreting the data, drafting the manuscript, undertaking the literature review and revising the article critically for important intellectual content.

Harris M. Wexler contributed to patient care, interpreting the data and revising the article critically for important intellectual content.

Both authors approved the final submitted manuscript.

Patient consent

Written informed consent was obtained from the patient for the publication of the case report and accompanying images.

Provenance and peer review

This article was not commissioned and was peer reviewed.

Funding

This research received no specific grant from any funding agency.

Declaration of competing interest

The authors declare that they have no competing interest regarding the publication of this case report.