An ectopic pregnancy or the development of a fertilized ovum outside the uterus: An abdominocyesis, also termed an abdominal pregnancy, can occur in a Fallopian tube and develop in the peritoneal cavity, usually secondary to an early rupture of a tubal pregnancy.

An abdominocyesis can also be the condition in which the embryo or fetus continues to grow in the abdominal cavity after its expulsion from the tube or other site of its primary development.