Late-Onset Oxytocin Anaphylaxis Triggering Severe Uterine Atony: A Case Report and Pathogenetic Insights

Key Clinical MessageAnaphylaxis to oxytocin may present with delayed onset and rapidly progress to life-threatening complications, including refractory uterine atony.Vigilant monitoring and high clinical suspicion are essential, especially in patients with allergic diathesis or other potential predisposing factors.AbstractOxytocin is the first-line uterotonic agent for labor induction and the prevention of postpartum hemorrhage [1,2].Allergic reactions to oxytocin are exceedingly rare and are most often reported as immediate hypersensitivity responses.Delayed-onset or biphasic anaphylaxis associated with oxytocin exposure has rarely been described [3][4][5].We report the case of a 41-year-old primigravida, with a pregnancy achieved through assisted reproductive technology, who developed severe anaphylaxis approximately eight hours after the initiation of a continuous intravenous oxytocin infusion for labor induction.The reaction was complicated by acute airway compromise, hemodynamic instability, and subsequent severe uterine atony refractory to oxytocin, necessitating prompt multimodal surgical and pharmacological management.This case highlights the potential for delayed-onset anaphylaxis following oxytocin administration and its possible association with uterine atony.Maintaining a high index of suspicion for this rare but potentially life-threatening complication is essential, particularly in patients with predisposing risk factors, and extended monitoring after oxytocin administration should be considered. Case reportA 41-year-old primigravida with a singleton pregnancy conceived via assisted reproductive technology was admitted at term for labor induction.Her medical history was notable for allergic diathesis, including