At the end of labour, the placenta is detached and the muscles of the uterus contract to close the vessels connecting the uterus and placenta. When the muscle tone is not strong enough to close the vessels and prevent bleeding, it is called uterine atony.
Generally caused by situations that distend the uterus, such as multiparity, or by alterations related to the placenta, such as the presence of placental debris, placental abruption and placenta praevia.
It is the most common cause of postpartum haemorrhage. It can be severe and life-threatening for the mother if action is not taken quickly.
The treatment of choice is a drug called oxytocin which promotes uterine contraction. In severe cases where bleeding persists, urgent surgery may be necessary; in very severe cases it may mean removal of the uterus.
- Michael A Belfort, MBBCH, MD, PhD, FRCSC, FRCOG. Overview of postpartum hemorrhage. UpToDate.
- Sheldon WR, Blum J, Vogel JP, et al. Postpartum haemorrhage management, risks, and maternal outcomes: findings from the World Health Organization Multicountry Survey on Maternal and Newborn Health. BJOG 2014; 121 Suppl 1:5.
- Marshall AL, Durani U, Bartley A, et al. The impact of postpartum hemorrhage on hospital length of stay and inpatient mortality: a National Inpatient Sample-based analysis. Am J Obstet Gynecol 2017; 217:344.e1.
- Wetta LA, Szychowski JM, Seals S, et al. Risk factors for uterine atony/postpartum hemorrhage requiring treatment after vaginal delivery. Am J Obstet Gynecol 2013; 209:51.e1.
