Ruptured corpus luteum with hemoperitoneum.

Rupture of the corpus luteum in a young woman can cause massive hemoperitoneum, seen as free fluid in the flanks and pelvis on abdominal films. Radiographic examination alone cannot distinguish hemorrhage due to a ruptured corpus luteum or ectopic pregnancy from pus due to a ruptured appendix or a tubo-ovarian abscess; however, the presence of nonclotting blood on culdocentesis excludes abdominal sepsis. If these symptoms and findings occur during the latter half of the menstrual cycle in a young woman of low parity who has a normal menstrual history and a negative pregnancy test, a ruptured corpus luteum is a more likely diagnosis than ectopic pregnancy.