To summarize the ultrasonographic features and clinical characteristics of pregnancy associated uterine artery pseudoaneurysms (UAPs), and to explore their pathogenesis.

Ultrasound images and clinical data of 21 patients with pregnancy associated UAPs admitted to our hospital from January 2016 to December 2020 were collected and analyzed.

The primary diseases included seven cases of trophoblastic tumor, two cases of cesarean section scar pregnancy, ten cases of embryo residue in early pregnancy, and two cases of placenta residue or implantation. Blood human choionic gonadotophin was found abnormally increased in 19 patients, with a median of 2573.30 (60.001, 2001.30) IU/L. Pathologic examination of 18 patients revealed degenerated villi or trophoblasts. The ultrasound findings were consistent with the characteristics of pseudoaneurysm; the feeding vessels were damaged and the blood flow leaked into the false cavity directly. Pulse Doppler revealed an arterial blood flow spectrum with high speed and low resistance index. In eight patients, the radial arteries were involved, and in the other 13 patients, the arcuate arteries were involved.

Invasion of the myometrium by villi or trophoblasts is an important pathogenic factor for pregnancy associated UAPs. Color Doppler ultrasound has significant importance in the diagnosis of pregnancy associated UAPs and in monitoring the efficacy of therapy in such patients.