Incidence, risk factors, and clinical outcomes of placental abruption in a tertiary hospital in Hong Kong: a retrospective case-control study

Abstract

Introduction: This study aims to identify risk factors for placental abruption and evaluate maternal and fetal outcomes of patients with placental abruption in a tertiary hospital in Hong Kong. Methods: Medical records of patients with placental abruption treated at the Tuen Mun Hospital between January 2017 and December 2021 were retrospectively reviewed. Data retrieved included patient demographics, alcohol/substance abuse and smoking status, obstetric history, antenatal characteristics, body mass index at first antenatal visit, clinical presentation, intrapartum events, complications, and maternal and perinatal outcomes. Each patient was matched with a control who delivered just before the patient. Results: Of 22 990 deliveries and 23 230 live births, there were 86 placental abruption cases; the incidence was 0.37%. After adjusting for confounders, the risk factor for placental abruption was a history of antepartum haemorrhage. Compared with controls, patients with placental abruption had higher rates of caesarean sections (91.9% vs 23.3%, p<0.001), postpartum haemorrhage (62.8% vs 15.1%, p<0.001), uterine atony (31.4% vs 3.5%, p<0.001), blood transfusion (25.6% vs 3.5%, p<0.001), and disseminated intravascular coagulopathy (7.0% vs 0%, p=0.029). Compared with controls, neonates complicated with placental abruption had lower Apgar score at 1 minute (7 vs 8, p<0.001), higher preterm birth rate (64.0% vs 9.3%, p<0.001), lower birth weight (2296.4 g vs 3088.8 g, p<0.001), and more perinatal morbidities. Patients with a Couvelaire uterus had higher rates of uterine atony (56.3% vs 27.0%, p=0.026), postpartum haemorrhage (93.8% vs 61.9%, p=0.014), disseminated intravascular coagulopathy (25.0% vs 3.2%, p=0.014), blood transfusion (68.8% vs 17.5%, p<0.001), and secondary intervention (25.0% vs 1.6%, p=0.005). Neonates born from patients with a Couvelaire uterus had higher rates of acidosis (umbilical cord blood pH <7.1) [53.3% vs 5.8%, p<0.001], lower Apgar score at 1 minute (25.0% vs 4.8%, p=0.028), and hypoxic-ischaemic encephalopathy (12.5% vs 0%, p=0.039). Conclusion: Clinicians should be vigilant for placental abruption in patients with antepartum haemorrhage, especially in high-risk patients with a history of placental abruption, hypertension, or pre-eclampsia. Early and consistent antenatal care is imperative to identify those with risk factors. Proper education and timely preventive management should be provided to improve maternal and fetal outcomes.