Key History

Key Physical Exam

Risk Factors for Ectopic Pregnancy

Differential Diagnosis

Diagnostic Testing

• Pregnancy Test – Perform a pregnancy test on all women of childbearing age with abdominal or pelvic pain or vaginal bleeding unless the patient has had a hysterectomy or is well past menopause. Do not rely on the patient’s history of regular menses, birth control, tubal ligation or abstinence.


• β-hCG Testing – Serum hCG values alone should not be used to diagnose an ectopic pregnancy; they should be correlated with the patient's symptoms, history and ultrasound findings. Serial β-hCG levels are monitored to assess the rise or fall of the hormone. A slower than expected rise or fall in β-hCG levels is suggestive of an ectopic pregnancy.


• Transvaginal Ultrasound – This is the primary imaging modality for diagnosing ectopic pregnancy. It allows for the direct visualization of an ectopic gestational sac, often seen as an extraovarian, round or elongated, solid tubal mass, or a tubal ring. The absence of an intrauterine pregnancy on TVUS when the serum β-hCG level is above the discriminatory zone (typically 1,500-2,000 mIU/mL) strongly suggests an ectopic pregnancy.

The Use of the Discriminatory Zone

• The “discriminatory level” is a value of β-hCG above which an IUP should reliably be seen on ultrasound. Previously suggested values of the discriminatory level were 1,500 mIU/mL for transvaginal scanning and about 6,000 mIU/mL for transabdominal scanning.
• To avoid the potential for misdiagnosis and possible mistaken interruption of an IUP that a woman hopes to continue, the 2018 ACOG Bulletin #193 recommends that the value of hCG used as the discriminatory level should be conservatively high (as high as 3,500 mIU/mL). Above this level of hCG, the ultrasound landmarks of a normal intrauterine gestation should be visible.
• Higher hCG levels are present in women with a multiple gestation, and they may have hCG levels above the traditional discriminatory levels before the pregnancy can be diagnosed on ultrasound.

Ultrasound Findings and What They Mean

• Ultrasound evidence of a normal IUP is defined as:
  • Normal appearing, double-ringed gestational sac and yolk sac
  • Fetal pole
  • Heartbeat
  
  (If one of these is not included in the report, there is no definite evidence of an IUP.)
  
  
• Findings highly suggestive of an ectopic are an adnexal sac-like ring or a complex or cystic mass.

Clinical Risk and Safety Pearls

• Diluted urine may cause a false-negative urine pregnancy test.
• The diagnosis of pregnancy in a woman with prior tubal sterilization should be considered an ectopic pregnancy until ruled out.
• There is no single β-hCG level that reliably distinguishes between a normal and an ectopic pregnancy.
• Ectopic pregnancy may be present with β-hCG below the discriminatory level. Do not use the discriminatory level to rule out the presence of an ectopic pregnancy.
• Patients discharged with a diagnosis of possible ectopic pregnancy should have precise discharge instructions regarding the time, date, and with whom to follow-up. Discharge instructions must include a plan to return to an emergency department for any significant change in condition.

Treatment

• Consult with OB-GYN for established or uncertain diagnosis of ectopic pregnancy.
• Methotrexate is the first-line treatment for hemodynamically stable patients with unruptured ectopic pregnancy. Methotrexate is administered as a single intramuscular dose of 50 mg/m². Candidates for methotrexate therapy should have a β-hCG level typically less than 5,000 IU/L, no fetal cardiac activity, and be compliant with follow-up.
• If the patient is in hemorrhagic shock and the practitioner suspects ectopic pregnancy, immediate consultation for laparotomy is warranted.