Ectopic Pregnancy - Making the Diagnosis
Ectopic Pregnancy: Making the Diagnosis
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.
- 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|
|• 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)|
|• Transvaginal ultrasound||0.88 (0.52-0.98)||0.99 (0.96-1.0)||111 (12-1028)||0.12 (0.03-0.55)|
- 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).
- The "discriminatory zone" continues to be debated - no consensus on the number
- A one-time hCG level does not rule out ectopic pregnancy
- Transvaginal ultrasound is the single-best test to assess for ectopic pregnancy.
- Patient symptoms have limited risk-stratification value.
Most predictive exam findings for ectopic pregnancy:
Cervical motion tenderness (positive LR = 4.9)
- Peritoneal findings (positive LR = 4.2-4.5)
- Adnexal mass (positive LR = 2.4)
- Crochet et al. Does this woman have an ectopic pregnancy? 2013; 309(16): 1722-9. [PubMed]