Grand Rounds

What Model is Best for Managing a Pregnancy of Unknown Location?

BACKGROUND AND PURPOSE:

Pregnancy of unknown location (PUL)
- Positive urine pregnancy test and
- Location of pregnancy not seen on transvaginal ultrasonography (TVS)
Bobdiwala et al. (BJOG, 2018) compared different methods for the management of PUL

Systematic review and meta-analysis
Inclusion
- PUL at initial ultrasound
- RCTs, case–control studies, cohort studies and observational studies
- Retrospective and prospective
4 models
- Single hCG cut-off level
- hCG ratio (48 hours/initial hCG)
- Single progesterone cut-off level
- ‘M4 model’: Logistic regression model based on hCG average and hCG ratio (see ‘Learn More – Primary Sources’ for previous M4 publication)
Primary outcome
- High risk: Accurate risk prediction of women initially diagnosed with a PUL having an ectopic pregnancy compared to
- Low risk: Failed PUL or intrauterine pregnancy (IUP)
Sensitivity and specificity were calculated for each diagnostic model

43 studies were included
High level of heterogeneity among papers for definitions of
- PUL
- Final outcomes
Areas under the curves (ROC) and 95% CIs for these four management protocols for the prediction of high risk (ectopic pregnancy) was
- Single hCG: 0.42 (0.00–0.99)
- hCG ratio: 0.69 (0.57–0.78)
- Single progesterone cut-off: 0.69 (0.54–0.81)
- M4 protocol: 0.87 (0.83– 0.91)

The M4 model that uses logistic regression analysis and incorporates both hCG levels and ratios was the best available approach for detecting ectopic pregnancy

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