Massive subchorionic thrombohaematoma (Breus' mole) causing postpartum haemorrhage: a case series and management strategy.

BACKGROUND: Breus' mole (massive subchorionic thrombohaematoma, MST) is a rare placental disorder that can cause catastrophic postpartum haemorrhage due to acute rupture of a high-tension haematoma. However, the mechanism of this haemorrhage remains insufficiently understood in clinical practice. CASE PRESENTATION: Case 1: A 31-year-old woman, G4P1, was admitted at 26⁺¹ weeks of gestation for intrauterine foetal death. She had a history of chronic hypertension and obesity. Serial ultrasound revealed progressive placental thickening (39→87→97 mm) with a massive subchorionic haematoma. Her haemoglobin concentration decreased rapidly from 112 to 48 g/L. During emergency forceps extraction of the placenta, acute rupture of the haematoma wall occurred, resulting in an instantaneous haemorrhage of approximately 1500 mL. The patient survived after massive blood transfusion. Placental pathology revealed a 9 × 7 × 2 cm haematoma beneath the chorionic plate, which was consistent with Breus' mole with maternal vascular malperfusion. Case 2: A 35-year-old primigravida was admitted at 26⁺³ weeks of gestation with threatened preterm labour. She had hypothyroidism, and the foetus had sex chromosome mosaicism. Serial ultrasound revealed progressive placental thickening (36→57→82→91 mm), with a haematoma covering 100% of the foetal surface and measuring up to 4.4 cm in thickness. Her haemoglobin concentration decreased in a stepwise manner from 118 to 78 g/L despite oral iron supplementation. Following multidisciplinary team assessment, labour was induced as planned, resulting in the spontaneous and complete delivery of the placenta, with an estimated blood loss of only 50 mL. Pathology confirmed Breus' mole. CONCLUSIONS: Postpartum haemorrhage caused by Breus' mole results from the acute physical rupture of a high-tension haematoma, a mechanism fundamentally different from that of uterine atony. "Progressive placental thickening, massive subchorionic haematoma, and unexplained progressive decline in haemoglobin concentration" constitute the core triad for prenatal warning. Proactive termination of pregnancy based on multidisciplinary assessment can effectively prevent catastrophic haemorrhage, enabling a paradigm shift from "reactive rescue" approach to a "proactive defence" approach.