In ectopic pregnancy, a fertilized ovum implants in an area other than the endometrial lining of the uterus (

Fig 14-7). More than 95% of extrauterine pregnancies occur in the fallopian tube.

The incidence of ectopic pregnancy has increased from 4.5/1000 in 1970 to 19.7/1000 in 1992. This may be due, at least in part, to a higher incidence of salpingitis, an increase in ovulation induction, and more tubal sterilizations.

Ectopic pregnancy is a significant cause of maternal morbidity and mortality as well as fetal loss. It is the leading cause of pregnancy-related death in the first trimester, and accounts for 9% of all pregnancy-related deaths. The development of sensitive β-hCG assays, along with the increasing use of ultrasound and laparoscopy, has allowed for earlier diagnosis of ectopic pregnancy. This has resulted in a decrease in both maternal morbidity and mortality.

Classification & Incidence

Ectopic pregnancy may be classified as follows (

Fig 14-7).

1. Tubal (> 95%) - Includes: ampullary (55%), isthmic (25%), fimbrial (17%), and interstitial (2%).

2. Other (< 5%) - Includes: cervical, ovarian, and abdominal (primary abdominal pregnancies have been reported, but most abdominal pregnancies are secondary pregnancies, from tubal abortion or rupture and subsequent implantation in the bowel, omentum, or mesentery).

3. Intraligamentous

4. Heterotopic pregnancy - An ectopic pregnancy occurs in combination with an intrauterine pregnancy in 1 in 15,000-40,000 spontaneous pregnancies, and in up to 1% of patients undergoing in vitro fertilization.

5. Bilateral ectopic - These pregnancies have occasionally been reported.