Haemoperitoneum secondary to a rupture of tortuous vessels from the serosal surface of the right uterine fundal region after coitus is a rare but life-threatening condition. This case demonstrates that even a very rare diagnosis should be considered, especially when dealing with patients with atypical presentations. This case report evidences a 31-year-old woman in her first pregnancy, presenting to our hospital triage at night for abdominal pain after sexual intercourse at a gestational age of 33 weeks and 4 days, and there was no history suggestive of endometriosis or fibroids. Apart from mild pain and slight pallor, she was stable. Her initial CTG was normal, but we noted two unprovoked decelerations about 8 and 10 hours after admission. During the morning rounds review, intra-abdominal bleeding was highly suspected and an emergency caesarean section was arranged. The on-call surgeon was also alerted, and a class I caesarean section was performed through the midline sub-umbilical incision. About 800 ml of intraoperative hemoperitoneum was noted upon opening the peritoneum. A male infant weighing 2.3 kg was delivered. Clear liquor was noted. Meanwhile, a small defect of about 1 cm in diameter with active bleeding from the underlying tortuous vessel was noted over the right posterior wall of the fundus. The underlying myometrium was intact and there was neither through nor through tear nor perforation. Discussion: The precise mechanism for postcoital haemoperitoneum due to rupture of uterine subserosal vessels is not known, but it is hypothesized that: pregnancy-with the increased friability of the tissues and fixation of the genital tract coincident with gestation; vigorous intercourse; coital positions; vaginismus and genital disproportion are the possible explanations. A complete gynaecological history, including endometriosis, fibroids, pelvic inflammatory disease, and any recent surgical procedures, is required to make a diagnosis. Ruptured ectopic pregnancy and ruptured corpus luteal cyst are on the top of the list of diagnoses in the early stage of pregnancy. The majority of such cases do not voluntarily admit the preceding act of coitus during initial presentation, and care must be taken to elicit a detailed sexual history. Interestingly, spontaneous haemoperitoneum in pregnancy complicated by endometriosis may occur during pregnancy. Conclusion: The study concludes that pregnant women with a history of the recent coitus present with acute abdominal pain, even in the absence of vaginal bleeding, haemoperitoneum has to be considered. On the other hand, idiopathic or spontaneous bleeding should be kept in mind even if there is no possible explanation.