Heterotopic pregnancy refers to nidation of the fertilized ovum outside the uterus. Clinically heterotopic pregnancy is classified into oviducal pregnancy, ovary pregnancy, abdominal pregnancy and cervical pregnancy,among which oviducal pregnancy is the most commonly encountered one and occupies about 90 % of heterotopic pregnancy and about 50 % is on the right side.
 

According to acute sharp pain and abdominal massive hemorrhage, heterotopic pregnancy is similar to abdominal pain during pregnancy, blood stasis in the lower abdomen and abdominal mass in TCM. Heterotopic pregnancy is usually caused by retention of stasis in the lower abdomen, unsmooth circulation of qi and blood in the thoroughfare and conception vessels that lead to fertilized ovum to stay in the lower abdomen; or by weakness of the viscera and consumption of qi and blood failing to transport the fertilized ovum to the uterus. Both conditions will lead to development of the fertilized ovum in the oviduct that dilates and ruptures the vessels, resulting in hemorrhage in the lower abdomen and blockage of the vessels.