Ectopic pregnancy, or preembryo implantation outside the endometrial cavity (i.e., fallopian tube, cervix, abdominal or pelvic cavity), is a potentially fatal condition with an incidence of 1:150 diagnosed pregnancies. Any woman of reproductive age presenting to an emergency department complaining of pelvic pain should be suspected of pregnancy, particularly ectopic pregnancy, until proven otherwise. Mortality associated with ectopic pregnancy in USA is estimated at 1:800; the condition is usually fatal if untreated.
Risk of ectopic pregnancy
Fallopian tubes are the most frequent sites for abnormal (ectopic) implantation, while interstitial, cervical, ovarian, and abdominal pregnancies are rare. Tubal ectopic pregnancy is characterized by pelvic cramping and vaginal spotting beginning shortly after the first missed menstrual period
Signs/symptoms of hemorrhage, shock, and peritoneal irritation are frequently found in ectopic pregnancy. The uterus may be enlarged (but still smaller than expected for gestational age), and a tender adnexal mass may be palpated. Undetected ectopic pregnancy of 6-8 wk gestational age may present suddenly with acute, sharp abdominal pain, followed by syncope. This sequence usually heralds tubal rupture and intraabdominal hemorrhage, and must be aggressively managed.
Findings of uterine asymmetry may be encountered in cornual (interstitial) pregnancy, and such ectopics may remain viable longer as the uterine wall provides support and delays rupture. Cornual ectopics may catastrophically rupture between 12-16 wks with massive blood loss; hysterectomy is sometimes necessary for adequate hemostasis. Orthostatic signs must be sought to identify urgent cases.
Following return of a positive urine or serum hCG test confirming pregnancy, transvaginal ultrasonography should be performed early in the ectopic evaluation. Serial hCG titres are helpful in equivocal cases, since this value should double q 48-72 h. In ectopic pregnancy, hCG doubling time is generally blunted. If hCG titres are >2000 mIU/mL an intrauterine gestational sac should be seen via sonogram; ectopic pregnancy is implicated if an empty uterus is found. Adnexal mass further supports the diagnosis of ectopic pregnancy and culdocentesis may also be helpful (blood from ectopic pregnancy aspirated from the cul-de-sac does not clot). Laparoscopy confirms the diagnosis.
An acute (surgical) abdomen militates against patient observation over a 48-72 h interval. Even if tubal pregnancy is correctly diagnosed before rupture, surgery is usually indicated. Nonoperative management may be considered for selected asymptomatic cases after ultrasound examination: if the ectopic is intact, sac size <3.5cm, and no fetal cardiac activity is present (relative contraindication). In these cases, a single dose of 50mg IM methotrexate (MTX) may be used. Documentation of normal liver function, CBC, and absence of other contraindications is mandatory. Follow-up with weekly hCG titres is important, as about 20% of these cases will fail MTX therapy and will still require surgery. Intercourse should be avoided during treatment.
The hallmark of ectopic pregnancy surgery is complete evacuation of the products of conception with conservation of normal anatomy where possible. Removal of the ectopic pregnancy is often accomplished by linear salpingostomy. If the tube is damaged and must be excised, an effort must be made to preserve as much healthy tube as possible. Subsequent tubal reconstructive surgery may permit a future conception. The surgeon is obliged to follow postoperative hCG titres until they return to pre-pregnancy levels; otherwise, incomplete resection must be considered.