Ruptured salpingitis isthmica nodosa: a rare cause for spontaneous haemoperitoneum.

Salpingitis isthmica nodosa (SIN) is the nodular swelling or diverticulum of the isthmus of the fallopian tube. It is most commonly identified when investigating female infertility or in association with ruptured ectopic pregnancies. We experienced a rare and atypical presentation of SIN. A 33-year-old woman presented with a 1-hour history of acute lower abdominal pain associated with nausea and vomiting. CT and pelvic ultrasound revealed haemoperitoneum with no radiological evidence for its aetiology. Initial beta-human chorionic gonadotropin excluded ectopic pregnancy. A diagnostic laparoscopy was performed following clinical deterioration of the patient. Active bleeding of the right fallopian tube was identified and managed with a right partial salpingectomy, with subsequent histopathology revealing ruptured SIN. There have been no reported cases of SIN being a primary cause for an acute abdomen or haemoperitoneum in the absence of an ectopic pregnancy, making this case a surgical novelty.