Effects of methotrexate on rabbit oviducts and on cell cultures of bovine oviduct epithelium

Medical therapy of ectopic gestation: contemporary paradigms

There has been an increase in the incidence of ectopic pregnancy to epidemic proportions in many developed countries in the past two decades. In 1989, ectopic pregnancy accounted for 1.6% of all pregnancies in the United States of America. This trend may be explained by an increase in the incidence of established risk factors as well as a dramatic improvement in diagnostic tools and advances in reproductive technology. Technologic advances such as highly sensitive radioimmunoassays for the β-subunit of human chorionic gonadotropin (βhCG), the development of high-resolution ultrasound and a heightened physician awareness have revolutionized the clinical management of ectopic pregnancy, leading to earlier and more consistent diagnoses and consequently reduced maternal mortality rates. 1,3–13 Unfortunately, ectopic pregnancy is still associated with a significant morbidity and mortality and contributes substantially to health-care costs. For example ectopic pregnancy complications accounted for 13% of all pregnancy-related deaths and were the leading cause of maternal mortality in African- American women in 1989. Financially, an estimated 1.1 billion dollars was spent in the United States of America alone for the management of ectopic pregnancy in 1990.

Ectopic pregnancy in animals and humans

Ectopic pregnancy denotes a pregnancy occurring elsewhere than in the cavity of the uterus. This pathology has been recognised for years and it causes numerous maternal deaths during the first trimester of pregnancy. While this condition is well-known in humans, it is rarely diagnosed in animals. However, the causes and mechanisms leading to an ectopic implantation of the ovum are not always clearly defined in humans or animals. Two types of ectopic pregnancy are mainly recognized: (1) tubal pregnancy occurs when an oocyte is fertilized and then remains in the oviduct and (2) abdominal pregnancy occurs when the gestation develops in the peritoneal cavity. The latter may be subdivided into two subtypes: the primary form, when a fertilized oocyte enters the peritoneal cavity and becomes attached to the mesentery or abdominal viscera, and the secondary form, which follows the rupture of an oviduct or the uterus after the fetus has been implanted, and the fetus is expelled into the peritoneal cavity. Cornual, ovarian and cervical ectopic locations are less frequent. Several differences exist in ectopic pregnancies between human beings and animal species. While abdominal pregnancy has been described in both human and animal species, tubal ectopic pregnancies would appear to be restricted to primates. Other than anecdotal cases, this pathological condition does not occur in laboratory, domestic or farm animals. Several factors are described as being the cause of these differences.