Risk factors for obstetric morbidity in patients with uterine atony undergoing caesarean delivery.

BACKGROUND: Uterine atony (UA) is recognized as a leading cause of postpartum haemorrhage. However, knowledge of risk factors of haemorrhage-related morbidity among patients diagnosed with UA is uncertain. We investigated risk factors for haemorrhage-related morbidity among patients undergoing Caesarean delivery with UA.

METHODS: We conducted a secondary analysis of data sourced from a 4-yr observational study at 19 US academic centres. Patients with UA were identified based on receiving methylergonovine or carboprost. Our primary outcome (haemorrhage-related morbidity) included a composite of intra- or postpartum transfusion; Caesarean hysterectomy; uterine or hypogastric artery ligation; intensive care admission for: pulmonary oedema, coagulopathy, adult respiratory distress syndrome, postoperative ventilation, or invasive line monitoring.

RESULTS: Among 57,182 patients who underwent Caesarean delivery, 2294 (4%) patients developed UA. Haemorrhage-related morbidity occurred in 450 (19.6%) patients with UA. The risk of haemorrhage-related morbidity was increased among African-Americans [adjusted odds ratio (aOR)=2.36; 95% confidence interval (CI)=1.73-3.23], Hispanics (aOR=1.4; 95% CI=1.04-1.9), women with multiple gestations (aOR=1.59; 95% CI=1.06-2.38), placenta praevia (aOR=4.89; 95% CI=3.04-7.87), patients with ASA class III (aOR=1.4; 95 CI=1.03-1.9), or ASA class IV (aOR=5.88; 95% CI=2.48-13.9), exposure to general anaesthesia (GA) (aOR=2.4; 95% CI=1.59-3.62) and combined general and regional anaesthesia (aOR=4.0; 95% CI=2.62-6.09), and ≥2 prior Caesarean deliveries (aOR=1.62; 95% CI=1.1-2.39).

CONCLUSIONS: Among patients with UA undergoing Caesarean delivery, the risk of haemorrhage-related morbidity is increased in African-Americans, Hispanics, patients with multiple gestations, placenta praevia, ASA class III or IV, ≥2 prior Caesarean deliveries and those undergoing GA.