Conservative medical treatment cured an interstitial tubal pregnancy complicated by a uterine artery pseudoaneurysm: a case report

Background Uterine artery pseudoaneurysm (UAP) is a localized hematoma that forms after the disruption of the uterine artery wall. Its outer layer is encapsulated by the surrounding tissues and lacks a true vascular wall structure. UAP is a rare complication following uterine arterial injury and often occurs secondary to intrauterine procedures, cesarean section or uterine surgery, and pregnancy. Ultrasound plays an important role in the timely diagnosis of UAP. We present a case of an interstitial tubal pregnancy complicated by UAP identified by ultrasound, which was successfully treated with conservative medication, achieving dual cure. Case summary A 23-year-old nulliparous woman presented with “49 days of amenorrhea and 11 days of vaginal bleeding with lower abdominal pain.” This pregnancy followed ovulation induction. Serum human chorionic gonadotropin ( β -hCG) was 607.3 mIU/mL, with no intrauterine gestational sac seen. She was diagnosed with ectopic pregnancy and started on conservative therapy with 100 mg of oral mifepristone daily. Due to a significant increase in β -hCG, on day 5 of treatment, she received 75 mg of intramuscular methotrexate in combination. On day 11, a color Doppler ultrasound revealed a left interstitial tubal pregnancy complicated by UAP (1.0 × 1.3 cm). After the diagnosis, methotrexate was administered again together with ongoing mifepristone, and β -hCG began to decline. On day 22, a third round of methotrexate was given; on day 26, the patient suddenly developed lower abdominal pain. An ultrasound showed a mixed echogenic mass in the left interstitial tubal region measuring 3.0 × 3.1 cm, no UAP, and a small amount of pelvic free fluid (1.4 cm). Expectant management was adopted. On day 32, her lower abdominal pain resolved, mifepristone was discontinued, and she was discharged. Complete blood count (CBC), liver function, and renal function were monitored throughout and remained normal. During conservative therapy with mifepristone, β -hCG fluctuated between 607.3 and 2,375 mIU/mL. Through three rounds of methotrexate combined with continuous mifepristone treatment, dual clinical cure of interstitial tubal pregnancy and UAP was achieved. A 6-month follow-up showed no recurrence of UAP in the left interstitial tubal area and normal serum β -hCG. Conclusion In interstitial tubal pregnancy complicated by UAP, ultrasound has important diagnostic value for UAP. A conservative medical regimen can have dual therapeutic effects on both the interstitial pregnancy and the UAP.