Tubal ectopic pregnancy. Light micrograph of a section through tissue from a fallopian tube, in a case of a tubal ectopic pregnancy. Ectopic pregnancies occur when a fertilised egg implants in tissue other than the uterine wall. The Fallopian tubes are the most common location, leading to a tubal ectopic pregnancy. If left undetected, the tube is likely to rupture and cause life-threatening haemorrhaging.