Incidence of ectopic pregnancy is about 2/100 diagnosed pregnancies.
Etiology of Ectopic Pregnancy
Factors that particularly increase risk of ectopic pregnancy include
Prior ectopic pregnancy (10 to 25% risk of recurrence)
History of pelvic inflammatory disease Pelvic Inflammatory Disease (PID) Pelvic inflammatory disease (PID) is a polymicrobial infection of the upper female genital tract: the cervix, uterus, fallopian tubes, and ovaries; abscess may occur. PID may be sexually transmitted... read more (particularly due to Chlamydia trachomatis)
Prior abdominal or particularly tubal surgery, including tubal ligation
Other specific risk factors for ectopic pregnancy include
Intrauterine device (IUD) use
Infertility due to tubal lesions
Prior induced abortion
Pregnancy is less likely to occur when an IUD is in place; however, about 5% of such pregnancies are ectopic.
Pathophysiology of Ectopic Pregnancy
The most common site of ectopic implantation is a fallopian tube, followed by the uterine cornua. Pregnancies in the cervix, a cesarean delivery scar, an ovary, the abdomen, or fallopian tube interstitium are rare.
Heterotopic pregnancy (simultaneous ectopic and intrauterine pregnancies) occurs in only 1/10,000 to 30,000 pregnancies but may be more common among women who have had ovulation induction or used assisted reproductive techniques Assisted Reproductive Techniques Assisted reproductive techniques (ARTs) involve manipulation of sperm and ova or embryos in vitro with the goal of producing a pregnancy. ARTs may result in multifetal pregnancy, but risk is... read more such as in vitro fertilization and gamete intrafallopian tube transfer (GIFT); in these women, the overall reported ectopic pregnancy rate is ≤ 1%.
The structure containing the fetus usually ruptures after about 6 to 16 weeks. Rupture results in bleeding that can be gradual or rapid enough to cause hemorrhagic shock. Intraperitoneal blood irritates the peritoneum. The later the rupture, the more rapidly blood is lost and the higher the risk of death.
Symptoms and Signs of Ectopic Pregnancy
Symptoms of ectopic pregnancy vary and are often absent until rupture occurs. Most patients have pelvic pain (which is sometimes crampy), vaginal bleeding, or both. Menses may or may not be delayed or missed, and patients may not be aware that they are pregnant.
Rupture may be heralded by sudden, severe pain, followed by syncope or by symptoms and signs of hemorrhagic shock or peritonitis. Rapid hemorrhage is more likely in ruptured cornual pregnancies.
Cervical motion tenderness, unilateral or bilateral adnexal tenderness, or an adnexal mass may be present. The uterus may be slightly enlarged (but often less than anticipated based on date of the last menstrual period).
Diagnosis of Ectopic Pregnancy
Quantitative serum beta–human chorionic gonadotropin (beta-hCG)
Ectopic pregnancy is suspected in any female of reproductive age with pelvic pain, vaginal bleeding, or unexplained syncope or hemorrhagic shock, regardless of sexual, contraceptive, and menstrual history. Findings of physical (including pelvic) examination are neither sensitive nor specific.
A ruptured ectopic pregnancy is a surgical emergency because it causes maternal hemorrhage and risk of death; prompt diagnosis is essential.
Pearls & Pitfalls
The first step is doing a urine pregnancy test, which is about 99% sensitive for pregnancy (ectopic and otherwise). If urine beta-hCG is negative and if clinical findings do not strongly suggest ectopic pregnancy, further evaluation is unnecessary unless symptoms recur or worsen. If urine beta-hCG is positive or if clinical findings strongly suggest ectopic pregnancy, quantitative serum beta-hCG and pelvic ultrasonography are indicated.
If quantitative serum beta-hCG is < 5 mIU/mL, ectopic pregnancy is excluded. If ultrasonography detects an intrauterine gestational sac, ectopic pregnancy is extremely unlikely except in women who have used assisted reproductive techniques (which increase risk of heterotopic pregnancy); however, cornual and intra-abdominal pregnancies may appear to be intrauterine pregnancies. Ultrasonographic findings suggesting ectopic pregnancy (noted in 16 to 32%) include complex (mixed solid and cystic) masses, particularly in the adnexa, and free fluid in the cul-de-sac.
If serum beta-hCG is above a certain level (called the discriminatory zone), ultrasonography should detect a gestational sac in patients with an intrauterine pregnancy. This level is usually about 2000 mIU/mL. If the beta-hCG level is higher than the discriminatory zone and an intrauterine gestational sac is not detected, an ectopic pregnancy is likely. Use of transvaginal and color Doppler ultrasonography may improve detection rates.
If the beta-hCG level is below the discriminatory zone and ultrasonography is unremarkable, patients may have an early intrauterine pregnancy or an ectopic pregnancy. If clinical evaluation suggests ectopic pregnancy (eg, signs of significant hemorrhage or peritoneal irritation), diagnostic laparoscopy may be necessary for confirmation.
If ectopic pregnancy appears unlikely and patients are stable, serum levels of beta-hCG can be measured serially on an outpatient basis (typically every 2 days). Normally, the level doubles every 1.4 to 2.1 days up to 41 days; in ectopic pregnancy (and in abortions), levels may be lower than expected by dates and usually do not double as rapidly. If beta-hCG levels do not increase as expected or if they decrease, the diagnoses of spontaneous abortion and ectopic pregnancy are reconsidered.
Prognosis for Ectopic Pregnancy
Ectopic pregnancy is fatal to the fetus, but if treatment occurs before rupture, maternal death is rare. In the US, ectopic pregnancy probably accounts for 9% of pregnancy-related maternal deaths.
Treatment of Ectopic Pregnancy
Surgical resection (usually)
Methotrexate for some small, unruptured ectopic pregnancies
Hemodynamically unstable patients require immediate laparotomy and treatment of hemorrhagic shock Hemorrhagic shock Shock is a state of organ hypoperfusion with resultant cellular dysfunction and death. Mechanisms may involve decreased circulating volume, decreased cardiac output, and vasodilation, sometimes... read more .
For stable patients, treatment is usually laparoscopic surgery; sometimes laparotomy is required. If possible, salpingotomy, usually using cautery or high-frequency (harmonic) ultrasound devices, is done to conserve the tube, and the products of conception are evacuated.
Salpingectomy is indicated in any of the following cases:
The ectopic pregnancy has ruptured.
The ectopic pregnancy is in the blind-ending distal segment in women who have had a previous partial salpingectomy.
The tube has been reconstructed.
Hemorrhage continues after salpingotomy.
The current pregnancy represents a chronic tubal pregnancy (a tubal pregnancy in which the tubal wall gradually disintegrates, with slow and/or repeated episodes of hemorrhaging leading to the formation of a pelvic mass).
No future childbearing is planned.
The ectopic pregnancy represents a failure of previous sterilization procedure.
Only the irreversibly damaged portion of the tube is removed, maximizing the chance that tubal repair can restore fertility. The tube may or may not be repaired. After a cornual pregnancy, the tube and ovary involved can usually be salvaged, but occasionally repair is impossible, making hysterectomy necessary.
Women can be given a single dose of methotrexate 50 mg/m2 IM if all of the following are present:
Unruptured tubal pregnancies are < 3 cm in diameter.
No fetal heart activity is detected.
The beta-hCG level is < 5,000 mIU/mL ideally, but up to 15,000 mIU/mL.
Beta-hCG measurement is repeated on about days 4 and 7. If the beta-hCG level does not decrease by 15%, a 2nd dose of methotrexate or surgery is needed. Alternatively, other protocols can be used. For example, the beta-hCG level can be measured on days 1 and 7, and a 2nd dose of methotrexate can be given if the level does not decrease by 25%. About 15 to 20% of women treated with methotrexate eventually require a 2nd dose.
The beta-hCG level is measured weekly until it is undetectable. Success rates with methotrexate are about 87%; 7% of women have serious complications (eg, rupture). Surgery is indicated when methotrexate is ineffective.
The most common site for ectopic pregnancies is a fallopian tube.
Symptoms can include pelvic pain, vaginal bleeding, and/or missed menses, but symptoms may be absent until rupture occurs, sometimes with catastrophic results.
Suspect ectopic pregnancy in any female of reproductive age with pelvic pain, vaginal bleeding, or unexplained syncope or hemorrhagic shock, regardless of history and examination findings.
If a urine pregnancy test is positive or clinical findings suggest ectopic pregnancy, determine quantitative serum beta-hCG and do pelvic ultrasonography.
Treatment usually involves surgical resection, but for certain ectopic pregnancies, methotrexate can be tried.