What scoring system is used to estimate the probability of pulmonary embolism in pregnant patients?

Scoring Systems for Pulmonary Embolism in Pregnant Patients

The Pregnancy-Adapted Geneva (PAG) Score is the most appropriate scoring system for estimating the probability of pulmonary embolism in pregnant patients, as it is specifically designed for this population and shows superior discriminative power compared to standard scoring systems. 1

Pregnancy-Specific Scoring Systems

Pregnancy-Adapted Geneva (PAG) Score

The PAG Score was developed specifically for pregnant women with suspected PE and includes seven items:

• Age ≥40 years
• Heart rate >110 beats per minute
• Previous history of DVT/PE
• Surgery or fracture within 4 weeks
• Unilateral lower limb pain
• Hemoptysis
• Pain on deep venous palpation and unilateral edema

Risk stratification with the PAG Score correlates with PE prevalence:

• Low risk: 2.3% PE prevalence
• Intermediate risk: 11.6% PE prevalence
• High risk: 61.5% PE prevalence 1

The PAG Score demonstrates superior discriminative power with an area under the curve of 0.795 compared to 0.684 for the standard Geneva score in pregnant women.

Pregnancy-Adapted YEARS Algorithm

Another approach specifically validated in pregnancy is the Pregnancy-Adapted YEARS Algorithm, which assesses:

• Clinical signs of deep vein thrombosis
• Hemoptysis
• PE as the most likely diagnosis
• D-dimer level

PE is ruled out if:

• None of the three clinical criteria are met AND D-dimer <1000 ng/mL, OR
• One or more criteria are met AND D-dimer <500 ng/mL 2

This algorithm safely ruled out PE across all trimesters and reduced the need for CT pulmonary angiography in 32-65% of pregnant patients, with higher efficiency in earlier trimesters.

Standard Scoring Systems (Less Optimal for Pregnancy)

Wells Score

While commonly used in the general population, the Wells Score has limitations in pregnancy as it:

• Includes subjective assessment ("alternative diagnosis less likely than PE")
• Was not validated specifically in pregnant women
• Contains parameters that may be affected by normal physiological changes of pregnancy 3

Revised Geneva Score

The standard Revised Geneva Score:

• Is fully standardized but not validated in pregnancy
• Includes age >65 years, which is rarely applicable to pregnant women
• Contains parameters with different weights that may lead to miscalculations 4, 5

Diagnostic Algorithm for Suspected PE in Pregnancy

1. Initial Assessment: Apply the PAG Score to determine pre-test probability

2. For patients with signs/symptoms of DVT:

   • Perform bilateral compression ultrasound of lower extremities
   • If positive, begin anticoagulation
   • If negative, proceed to further testing 3

3. For patients without signs/symptoms of DVT:

   • Proceed directly to pulmonary vascular studies 3

4. Chest X-ray:

   • First radiation-associated procedure in all cases 3

5. Based on CXR results:

   • Normal CXR: Proceed to lung scintigraphy (V/Q scan)
   • Abnormal CXR: Proceed to CT pulmonary angiography 3

6. For non-diagnostic V/Q scan:

   • Proceed to CT pulmonary angiography rather than clinical management alone 3

Important Caveats

• D-dimer testing is not recommended for excluding PE in pregnant women due to poor specificity (15%) and inadequate sensitivity (73%) 6

• Radiation concerns should not prevent necessary imaging, as properly performed diagnostic tests pose minimal risk to the fetus 6

• Common pitfalls include misattribution bias (assuming shortness of breath is physiological in pregnancy) and diagnostic anchoring (attributing symptoms to pre-existing conditions) 6

• For unstable patients or when studies are not immediately available, empiric anticoagulation should be considered while awaiting diagnostic test results 3