Intracellular Calcium Response to Oxytocin in Uterine Smooth Muscle Cells From Patients With Uterine Atony

( Anesth Analg . 2025;140(2):491–493. DOI: 10.1213/ANE.0000000000007240) Postpartum hemorrhage (PPH) is a leading cause of maternal death globally, with uterine atony being responsible for about 80% of these cases. In the United States, it is the second-highest pregnancy-related cause of death. Uterine atony occurs when the uterus fails to contract properly after the delivery of the placenta, and it remains a challenge to study due to the lack of effective in vivo or in vitro models. Cytosolic calcium (Ca 2+ ) plays a critical role in muscle contraction, including uterine smooth muscle, and its response to stimuli such as oxytocin is central to understanding uterine atony. This study aimed to investigate whether oxytocin-induced calcium changes in uterine smooth muscle cells (USMCs) could provide insight into uterine atony.