Uterine artery pseudoaneurysm resulting from hidden Uterine artery pseudoaneurysm resulting from hidden uterine rupture misinterpreted as a lower uterine segment myoma Ajlana Mulic-Lutvica Institution of Women’s and Children’s Health, Obstetrics &Gynaecology, Uppsala University Case report A 36-year-old woman presented with severe lower abdominal pain 6 days after her third delivery which was performed by Kiwi Ventouse. No fever, no vaginal bleeding, normal sparse lochia. She required a huge amount of analgetics. Gynaecological examination revealed a tender postpartum uterus and a round painful mass on the right side of the uterus was palpated. Transabdominal ultrasound showed a round mass 6.8x5.4 cm large, with almost the same echogenicity as adjacent myometrium, in the right side of the lower uterine segment (Fig 1). Initially a necrotic myoma in the lower uterine segment was suspected. By pulse Doppler the right uterine artery with a low resistance and a high peak systolic velocity (120cm/sec), without early diastolic notch was observed above this round mass (Fig 2). A turbulent flow from the uterine artery towards a hypoechoic area was noted. A high resistance flow with a pulsatility index (PI) 3.78 and a resistance index (RI) 0.94 was measured inside this hypoechoic area. Blue colour showed that the direction of the blood flow was away from the probe and from the uterine artery. A reversed flow back towards uterine artery was also recorded and showed that there was a communication between the uterine artery and this hypoechoic area (Fig 3) “to and fro sign”. Despite Doppler findings suggestive of a pseudoaneurysm, clinical finding was interpreted as lower uterine segment myoma with necrosis. Figure 2. A large hypoechoic area inside the mass surrounded by echogenic limb, interpreted as a necrotic myoma, was actually a typical pseudoaneurysm with a narrow neck. Figure 3. “to and fro sign” Figure 1 a and b. A round mass in the lower uterine segment which was interpreted as necrotic myoma (longitudinal and transverse section) On postpartum day 8, severe secondary postpartum haemorrhage suddenly occurred. Manual exploration of the uterus revealed a large defect on the right backside of the uterus. Pelvic embolization of the right uterine artery with several coils was performed and initially the bleeding was stopped. A short time later patient became hemodynamically unstable and required a subtotal hysterectomy. Total amount of bleeding was estimated 10 L. The presentation with severe abdominal pain and not puerperal haemorrhage, a finding of an uterine mass on gynaecological and ultrasound examination as well as lack of previous uterine scar, were contributing factors for misdiagnosis of necrotic myoma. A differential diagnosis of uterine artery pseudoaneurysm should be considered always when postpartum complications arises, particularly with severe abdominal pain. Doppler ultrasound signs of pseudoaneurysm are obvious and the knowledge of these signs should be disseminated.