<prompt> In ectopic pregnancy, the most common reaction seen in uterus isDecidual reactionArias stella reactionDouble decidual sac signStallwohy sign  <response>: Decidual reaction : Increased structural and secretory activity of the endometrium that is brought about in response to progesterone Progesterone levels fall due to fall in the hcG levels Endometrium sloughs out causing uterine bleeding. Ref: Dutta Obs 9e pg 169. 