A Case of Uterine Arteriovenous Fistula Associated With Adenomyosis and Pregnancy.

Uterine arteriovenous fistula (UAVF) associated with adenomyosis during pregnancy is a rare, life-threatening condition. This report describes a 36-year-old woman with adenomyosis who conceived through in vitro fertilization-embryo transfer and experienced recurrent vaginal bleeding in early pregnancy, followed by spontaneous miscarriage at 14 weeks. One month post-miscarriage, she developed a delayed massive hemorrhage. Color Doppler ultrasound revealed mosaic blood flow signals and high-velocity low-resistance spectra (resistance index 0.52) within the myometrium, confirming acquired UAVF. Emergency uterine artery embolization achieved successful hemostasis while preserving bilateral uterine artery trunks. Menstruation resumed 3 months postoperatively. This case raises the hypothesis of a possible association between adenomyosis and pregnancy-related UAVF. In patients with adenomyosis who are pregnant, recurrent early bleeding that is unresponsive to conservative therapy should raise suspicion for underlying vascular abnormalities, and color Doppler ultrasound evaluation may be warranted. Delayed explosive post-miscarriage hemorrhage refractory to uterotonics is characteristic. UAE is the preferred fertility-sparing treatment, with individualized embolization strategies and long-term follow-up essential.