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Industry: Email Alert RSS FeedEctopic Pregnancy
American Family Physician, Feb 15, 2000 by Josie L. Tenore
Ectopic pregnancy occurs at a rate of 19.7 cases per 1,000 pregnancies in North America and is a leading cause of maternal mortality in the first trimester. Greater awareness of risk factors and improved technology (biochemical markers and ultrasonography) allow ectopic pregnancy to be identified before the development of life-threatening events. The evaluation may include a combination of determination of urine and serum human chorionic gonadotropin (hCG) levels, serum progesterone levels, ultrasonography, culdocentesis and laparoscopy. Key to the diagnosis is determination of the presence or absence of an intrauterine gestational sac correlated with quantitative serum beta- subunit hCG (s-hCG) levels. An ectopic pregnancy should be suspected if transvaginal ultrasonography shows no intrauterine gestational sac when the s-hCG level is higher than 1,500 mlU per mL (1,500 IU per L). If the s-hCG level plateaus or fails to double in 48 hours and the ultrasound examination fails to identify an intrauterine gestational sac, uterine curettage may determine the presence or absence of chorionic villi. Although past treatment consisted of an open laparotomy and salpingectomy, current laparoscopic techniques for unruptured ectopic pregnancy emphasize tubal preservation. Other treatment options include the use of methotrexate therapy for small, unruptured ectopic pregnancies in hemodynamically stable patients. Expectant management may have a role when s-hCG levels are low and declining. (Am Fam Physician 2000;61:1080-8.)
Ectopic pregnancy is any pregnancy in which the fertilized ovum implants outside the intrauterine cavity. More than 95 percent of ectopic pregnancies occur in the fallopian tubes.1 Another 2.5 percent occur in the cornua of the uterus, and the remainder are found in the ovary, cervix or abdominal cavity.1 Because none of these anatomic sites can accommodate placental attachment or a growing embryo, the potential for rupture and hemorrhage always exists. A ruptured ectopic pregnancy is a true medical emergency. It is the leading cause of maternal mortality in the first trimester and accounts for 10 to 15 percent of all maternal deaths.2-4
Modern advances in ultrasound technology and the determination of serum beta-subunit human chorionic gonadotropin (b-hCG) levels have made it easier to diagnose ectopic pregnancy. Nonetheless, the diagnosis remains a challenge.
Epidemiology
The number of ectopic pregnancies has increased dramatically in the past few decades. Based on hospital discharge data, the incidence of ectopic pregnancy has risen from 4.5 cases per 1,000 pregnancies in 19705,6 to 19.7 cases per 1,000 pregnancies in 1992.2 The rise can be attributed partly to increases in certain risk factors but mostly to improved diagnostics. Some ectopic pregnancies detected today, for instance, would have spontaneously resolved without detection or intervention in the past. Ectopic pregnancy is more often detected in women over 35 years of age and in non-white ethnic groups.1
The case-fatality rate has declined from 35.5 maternal deaths per 10,000 ectopic pregnancies in 1970 to only 3.8 maternal deaths per 10,000 ectopic pregnancies in 1989.6 Even though overall survival has increased, the risk of death associated with ectopic pregnancy remains higher among black and other non-white minority women.
Risk Factors
Several factors increase the risk of ectopic pregnancy (Table 1). These risk factors share a common mechanism of action-namely, interference with fallopian tube function. Normally, an egg is fertilized in the fallopian tube and then travels down the tube to the implantation site. Any mechanism that interferes with the normal function of the fallopian tube during this process increases the risk of ectopic pregnancy. The mechanism can be anatomic (e.g., scarring that blocks transport of the egg) or functional (e.g., impaired tubal mobility).
In the general population, pelvic inflammatory disease is the most common risk factor for ectopic pregnancy. Organisms that preferentially attack the fallopian tubes include Neisseria gonorrhoeae, Chlamydia trachomatis and mixed aerobes and anaerobes. Unlike mixed aerobes and anaerobes, N. gonorrhoeae and C. trachomatis can produce silent infections. In women with these infections, even early treatment does not necessarily prevent tubal damage.7
Intrauterine devices (IUDs) used for contraception do not increase the risk of ectopic pregnancy, and no evidence suggests that currently available IUDs cause pelvic inflammatory disease. One explanation for the mistaken association of IUDs with ectopic pregnancy may be that when an IUD is present, ectopic pregnancy occurs more often than intrauterine pregnancy.1,8 Simply because IUDs are more effective in preventing intrauterine pregnancy than ectopic pregnancy, implantation is more likely to occur in an ectopic location.
Previous ectopic pregnancy becomes a more significant risk factor with each successive occurrence. With one previous ectopic pregnancy treated by linear salpingostomy, the recurrence rate ranges from 15 to 20 percent, depending on the integrity of the contralateral tube.1,9 Two previous ectopic pregnancies increase the risk of recurrence to 32 percent, although an intervening intrauterine pregnancy lowers this rate.1,10
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