Ectopic Pregnancy - Making the Diagnosis

Author: Javier Benitez, MD
Updated: 5/9/2013

Ectopic Pregnancy: Making the Diagnosis

JAMA Rational Clinical Examination Series

Systematic review based on 14 studies (n=12,101) with a summary prevalence of ectopic pregnancy of 15% (95% CI, 10-22%) in women presenting with abdominal pain or vaginal bleeding.

Background

  • Leading cause of maternal death in the first trimester of pregnancy
  • Incidence as high as 2.6%
  • Heterotopic pregnancy: Incidence = 0.3-0.8% (1-3% if assisted reproduction)
  • #1 cause of 1st trimesterpregnancy-related death
  • 8-31% initially diagnosed as “pregnancy of unknown location” (PUL), despite beta-hCG and ultrasonography
  • More than half of patients with ectopic pregnancy will have ZERO risk factors

Discriminatory zone: Serum beta-HCG level cutoff above which intrauterine pregnancy is likely visible on ultrasound.

  • Variable definition of cutoff with range of 1,500-3,000 mIU/mL
  • No single serum beta-hCG value is predictive of an ectopic pregnancy
  • If beta-HCG ≥3,000 mIU/mL and an “empty uterus” on ultrasound, suggestive of ectopic pregnancy

Diagnostic Tools to Risk Stratify

Finding Sensitivity Specificity (+) LR (-) LR
PHYSICAL EXAM | |
• Cervical motion tenderness 0.45 (0.33-0.57) 0.91 (0.80-0.96) 4.9 (1.7-14) 0.62 (0.47-0.83)
• Peritoneal findings 0.23-0.27 0.94-0.95 4.2-4.5 0.78-0.81
• Adnexal mass 0.09 (0.02-0.27) 0.96 (0.92-0.98) 2.4 (1.6-3.7) 0.94 (0.87-1.0)
• Adnexal tenderness 0.61 (0.52-0.69) 0.65 (0.42-0.83 1.9 (1.0-3.5) 0.57 (0.48-0.67)
IMAGING | |
• Transvaginal ultrasound 0.88 (0.52-0.98) 0.99 (0.96-1.0) 111 (12-1028) 0.12 (0.03-0.55)

Ultrasound:

  • Findings of an intrauterine pregnancy (IUP) such as gestational sac or fetal pole ruled out ectopic pregnancy, except in rare cases of heterotropic prengnacy.
  • Bedside ultrasound is the single most useful diagnostic test (positive LR = 111).

Beta hCG:

  • The "discriminatory zone" continues to be debated - no consensus on the number
  • A one-time hCG level does not rule out ectopic pregnancy

CONCLUSIONS:

  1. Transvaginal ultrasound is the single-best test to assess for ectopic pregnancy.
  2. Patient symptoms have limited risk-stratification value.

  3. Most predictive exam findings for ectopic pregnancy:

  4. Cervical motion tenderness (positive LR = 4.9)

  5. Peritoneal findings (positive LR = 4.2-4.5)
  6. Adnexal mass (positive LR = 2.4)

Fagan Nomogram

Fagan nomogram

References

  • Crochet et al. Does this woman have an ectopic pregnancy? 2013; 309(16): 1722-9. [PubMed]