ECTOPIC PREGNANCY

ECTOPIC PREGNANCY In ectopic pregnancy, implantation occupies at a site other than the endometrium. Ectopic pregnancies are responsible for approximately 10 percent of all maternal mortality. The prognosis for future reproduction is poor. Only one half of women having an ectopic pregnancy are eventually delivered of a liveborn infant.

ECTOPIC PREGNANCY Most of these never become pregnant, and up to 25 percent of those who do suffer a repeat ectopic pregnancy. Various factors contribute to ectopic pregnancies, the most common being infection. Unlike intrauterine spontaneous abortions, genetic factors are not paramount in the etiology of ectopic pregnancy. Ectopic embryos show chromosomal abnormalities no more often than predicted on the basis of embryonic age.

Incidence The incidence of recorded ectopic gestation is increasing. Some of this increase seems real and some spurious. A true increase can be hypothesized as a result of 1) improved treatment for pelvic inflammatory disease, a condition that in the past would have conferred sterility; (2) an increase in surgical corrections of fallopian tube occlusion; and

Incidence (3) a greater number of elective sterilizations, some of which are later reversed surgically. There is also an artificial increase related to improved diagnostic techniques. Ectopic pregnancies that in the past would have been mislabeled as unexplained abdominal pain or bleeding are readily recognized today because pregnancy tests have become very sensitive.

SITE Most ectopic pregnancies (96 percent) are tubal. The remainder are interstitial uterine ectopic pregnancies and, rarely, cervical, abdominal, or ovarian pregnancies. Most tubal pregnancies are located in the distal (ampullary) two thirds of the tube. A few ectopic pregnancies are isthmic, located in the proximal portion of the extrauterine part of the tube. On rare occasions both intrauterine and extrauterine gestations can coexist (heterotopic pregnancy).

Signs and Symptoms Abdominal pain and irregular vaginal bleeding are the most common presenting symptoms in ectopic pregnancy. In a 1983 report of 328 patients presenting with ectopic pregnancy, 94 percent had pain, 89 percent had a missed menstrual period, 80 percent had vaginal bleeding, and 20 percent had hypotension. An abdominal mass is palpable in only one half of patients with an ectopic pregnancy.

Signs and Symptoms Passage of a decidual cast in association with vaginal bleeding nearly unequivocally indicates ectopic pregnancy, but this is uncommon. Ectopic pregnancies should be diagnosed before the onset of hypotension, bleeding, pain, and overt rupture. Patients with a history of tubal surgery, pelvic inflammatory disease, tubal disease, or previous ectopic pregnancy are at special risk for ectopic pregnancy and would benefit not only from their physicians' vigilance but also from routine hormone screening.

Signs and Symptoms Ectopic pregnancy can be detected by 6 weeks' gestation, often as early as at 4½ gestational weeks. Chronic ectopic pregnancy is a distinct entity. Diagnosis may be difficult because normal anatomic landmarks are distorted by the formation of adhesions resulting from chronic inflammatory processes.

Signs and Symptoms Chronic ectopic pregnancies present a management quandary because the significance of the associated declining β-hCG levels is difficult to determine. The dilemma is whether resolution will occur spontaneously or require surgical intervention to prevent catastrophic hemorrhage and permanent adhesion formation resulting in tubal damage.

Diagnosis Direct vision by laparoscopy has been the diagnostic standard for ectopic pregnancy. Algorithms incorporating a single measurement of serum progesterone, serial measurement of the β-subunit of hCG, pelvic ultrasonography, and uterine curettage are accepted.

Algorithm for the diagnosis of unruptured ectopic pregnancy without laparoscopy.

Uterine Curettage Villi float in saline, a characteristic permitting identification of tissue obtained by curettage. If no villi are recognized and a decrease in the β-hCG level of 15 percent or more 8 to 12 hours occurs after curettage, a completed abortion can be assumed to exist. If villi are not visualized and β-hCG titers plateau or rise, trophoblasts can be assumed not to have been removed by the uterine curettage; thus, an ectopic pregnancy can be presumed to be present.

Surgical Treatment Salpingectomy by laparotomy has long offered almost a 100 percent cure. Laparoscopic salpingostomy and partial salpingectomy are rapidly replacing laparotomy. Laparotomy should be performed only when a laparoscopic approach is too difficult, the surgeon is not trained in operative laparoscopy, or the patient is hemodynamically unstable.

Surgical Treatment Postoperative bleeding, elevated β-hCG levels indicative of persistent viable trophoblastic tissue, and other symptoms occur in up to 20 percent of cases after conservative laparoscopic surgery. Excision of the involved oviduct or medical therapy may then be necessary.

Medical Treatment Although operative laparoscopy has substantially fewer complications than laparotomy, there remains irreducible morbidity intrinsic to surgery and anesthesia. Medical treatments can greatly reduce this morbidity. The agent used is the folic acid antagonist methotrexate, which inhibits synthesis of purines and pyrimidines and thus interferes with DNA synthesis and cell multiplication.

Medical Treatment Hemodynamically stable patients with ectopic pregnancies are eligible for treatment with methotrexate if the mass is unruptured and measures 4 cm or less in diameter by ultrasound. Patients with larger ectopic masses, embryonic cardiac activity, or evidence of acute intra-abdominal bleeding (acute abdomen, hypotension, or falling hematocrit) are not eligible for methotrexate therapy