Pregnancy-associated uterine artery pseudoaneurysm (UAP) usually requires transarterial embolization (TAE) irrespective of the presence/absence of current bleeding. Some UAP cases spontaneously resolve without TAE; however, such UAP is not well characterized. Here, we suggest that Pulse Wave Doppler may become an addition to predict its spontaneous resolution. A woman underwent 1st-trimester vaginal termination. Vaginal bleeding repeated and, 36 days later, an intrauterine low-echoic mass (24 mm) with swirling blood flow and arterial waveforms (Pulse Wave Doppler) and an enhanced intrauterine sac-like structure without current extravasation were observed, leading to the diagnosis of UAP. Subsequently, the low-echoic mass mostly disappeared but the swirling flow was still observed, with Pulse Wave Doppler revealing arterial flow but the absence of diastolic flow. Finally, the flow disappeared and UAP resolved. This observation reconfirmed spontaneous UAP resolution. The "absent diastolic flow," possibly indicative of decreased intrasac blood flow, may be a candidate for predicting UAP resolution.