Vascular Malformations as a Cause of Postpartum Hemorrhage

Uterine vascular malformations (UVM) leading to postpartum hemorrhage (PPH) are rare. The worldwide literature consists of case reports and small case series, and while the true incidence is unknown, it is likely to represent a very small proportion of causes of PPH. UVM can be congenital but are more commonly acquired when they tend to present with secondary PPH, although in rare instances they present with primary or even tertiary bleeding1. As a general rule, primary PPH occurring temporally close to delivery most likely is a result of a pre-existing arteriovenous malformation (AVM), whereas secondary or tertiary PPH is more likely due to an acquired pseudoaneurysm. Secondary PPH occurs in up to 0.5–1.5% of pregnancies2 and the vast majority of women who present with secondary or tertiary PPH will have endometritis with or without retained products of conception (RPOC). Their management usually consists of broad spectrum antibiotics and, if necessary, an evacuation of RPOC. The vast majority of these women stop bleeding thereafter. Because some women receive multiple courses of antibiotics and evacuation procedures without evidence of infection or RPOC, clinicians finally start to consider vascular malformations rather than persevering with repeated ineffective treatments.