Posterior vaginal fornix aspiration for the diagnosis of ectopic pregnancy is a simple and reliable method of diagnosis. It is indicated in cases where intra-abdominal bleeding is suspected. Intra-abdominal bleeding is most likely to accumulate in the recto-uterine sink, and even if the bleeding is small, bloody fluid can be drawn by posterior fornix aspiration. The presence of hemoperitoneum is indicated by a positive posterior fornix puncture when dark red non-clotting blood is drawn. In the case of old ectopic pregnancy, small blood clots or non-clotting old blood can be drawn. If the puncture needle is mistakenly inserted into a vein, the blood is redder and the specimen is left for about 10 minutes to coagulate. In the absence of internal bleeding, low internal bleeding, high location of the hematoma or adhesions in the recto-uterine trap, blood may not be drawn and thus a negative posterior fornix puncture does not negate the presence of ectopic pregnancy.