Young lady presents with acute abdominal pain and history of 1 1/2 months amenorrhoea. On USG examination there is collection of fluid in the pouch of douglas and empty gestational sac. Diagnosis is:

With sonographic absence of a uterine pregnancy, a positive assay for beta-hCG, fluid in the cul-de-sac, and an abnormal pelvic mass, ectopic pregnancy is almost ceain. Without early diagnosis, the natural history of "classical" cases is characterized by variably delayed menstruation followed by slight vaginal bleeding or spotting. With rupture, there is usually severe lower abdominal and pelvic pain that is frequently described as sharp, stabbing, or tearing. There is tenderness during abdominal palpation, and bimanual pelvic examination, especially cervical motion, causes exquisite pain. Ref: Leveno K.J., Hauth J.C., Rouse D.J., Spong C.Y. (2010). Chapter 10. Ectopic Pregnancy. In K.J. Leveno, J.C. Hauth, D.J. Rouse, C.Y. Spong (Eds), Williams Obstetrics, 23e.