A 40-year-old woman presented to the emergency department (ED) complaining of sharp, localized right lower quadrant (RLQ) abdominal pain for 1 day associated with vaginal spotting for 1 week. Her history included four previous pregnancies resulting in healthy births, with the last pregnancy being 5 years previously. The patient denied being pregnant, stating that her menstrual cycle had always been regular and reporting her last menstrual period (LMP) as 2 weeks ago. She had no fever, chills, vomiting, dizziness, or urinary tract symptoms. The patient denied any history of pelvic inflammatory disease (PID) or any sexually transmitted disease. Hypertension was diagnosed 2 years before and treated successfully with diet and exercise. There were no previous surgeries. The patient was taking no medications, and she denied any allergies, smoking, alcohol abuse, or use of recreational drugs. The review of symptoms was otherwise negative.
Vital signs were BP, 138/84 mm Hg; pulse, 85 beats per minute and regular; respirations, 19 breaths per minute; and temperature, 98ºF (36.7ºC). The patient's general appearance revealed mild distress, due to abdominal pain. The heart and lung examinations were unremarkable. The abdominal examination was positive for RLQ tenderness with voluntary guarding. The pelvic examination revealed right adnexal tenderness with an associated palpable mass and scant blood in the vaginal vault, with a closed cervical os. The result of a urine pregnancy test was positive. Emergent bedside ultrasonography (US) was performed in the ED.
Ectopic pregnancy
As the initial screening method to rule out ectopic pregnancy (EP), bedside US is increasingly used in many EDs. In the United States, EP is still the leading cause of first-trimester maternal death. The incidence increased more than fourfold from 1970 to 1992; the CDC estimates that almost 2% of all pregnancies are ectopic.1 Up to 50% of cases of EP are misdiagnosed at initial presentation, and morbidity and mortality can be significantly decreased if EP is promptly identified and treated prior to rupture.2-4
The causes and risk factors for EP are numerous, but most patients have no identifiable risk factor.5 Evidence supports a history of prior tubal damage leading to physiologic alterations in embryo transport. The most common associated pathology is PID caused by Chlamydia trachomatis.6 Other risk factors are previous tubal ligation and surgery, prior EP, endometriosis, previous pelvic surgery, use of a progesterone-impregnated intrauterine contraceptive device, increased maternal age, a history of infertility and infertility treatments, uterotubal anomalies, in utero exposure to diethylstil-bestrol, and cigarette smoking.7-13 Lesser risk factors include multiple sexual partners, early age at first intercourse, and vaginal douching.9-11
Diagnosis
The fallopian tube is the site of 95% of EPs, with the balance in the cervix, ovary, or abdomen. Physical examination may demonstrate cervical motion tenderness, abdominal tenderness, an adnexal mass, or mild uterine enlargement but can be unreliable since findings are most often nonspecific, particularly with a small, unruptured EP. Traditionally, the diagnosis has been based on the overall clinical picture with an emphasis on the signs and symptoms (see Tables 1 and 2).
Laboratory tests should include a CBC, urinalysis, blood typing with determination of Rh factor, and test for quantitative beta-human chorionic gonadotropin (hCG). The rate of increase in serum beta-hCG levels is predictable and measurable in pregnancy, rising rapidly, doubling in concentration every 2 to 3 days, and peaking at around 100,000 to 200,000 mIU/mL, which corresponds approximately to the 10th week of pregnancy.
The discriminatory zone is the range of quantitative serum beta-hCG concentrations above which a gestational sac can be visualized consistently by US.12 The transabdominal sonography (TAS) examination should consistently detect an intrauterine sac when the betahCG level is greater than 6,500 mIU/mL (corresponding to a 6-week gestation). The transvaginal sonogram (TVS) has increased sensitivity, with higher resolution, and can diagnose an intrauterine pregnancy (IUP) 1 week earlier, with a lower discriminatory zone (beta-hCG level between 1,000 and 1,800 mIU/mL).14
Urinary beta-hCG testing is the most common method for confirming pregnancy. Urine enzyme-linked immunosorbent assays detect beta-hCG levels of 50 mIU/mL, which correspond to a pregnancy at 3 to 4 days after implantation. Serum and urinary assays for beta-hCG have become so sensitive and specific that they are nearly always positive by the time an EP becomes symptomatic. Thus, in nearly all cases, a negative pregnancy test effectively rules out the diagnosis of EP, allowing the practitioner to focus on other gynecologic, GI, or renal causes of symptoms.15 Upon confirmation of pregnancy, pelvic US and serum quantitative beta-hCG levels can provide the necessary data to accurately assess early pregnancy.