RT Journal Article SR Electronic T1 Idiopathic spontaneous haemoperitoneum at 4 weeks gestation JF BMJ Case Reports JO BMJ Case Reports FD BMJ Publishing Group Ltd SP e244470 DO 10.1136/bcr-2021-244470 VO 14 IS 9 A1 Emily O'Brien A1 Rehan Feroz A1 Sona Jasani YR 2021 UL http://casereports.bmj.com/content/14/9/e244470.abstract AB A 20-year-old nulliparous patient with acute-onset abdominal pain and imaging suggestive of haemoperitoneum was admitted for observation. Though, initially, haemodynamically stable, her clinical picture worsened throughout her hospitalisation and warranted two separate laparoscopies that revealed 1200 mL and 50 mL of haemoperitoneum, respectively, without an identifiable bleeding source. After serial β-human chorionic gonadotropin levels and ultrasound confirmation of a viable pregnancy 23 days later, the patient underwent a normal antenatal course and delivered a healthy infant at 37 weeks gestation. This unusual case highlights the need to consider spontaneous haemoperitoneum in pregnancy as a diagnosis, particularly in the setting of pregnancy of unknown location, even at an early stage of pregnancy.