Diagnosis PE in pregnancy

PE: pulmonary embolism; DVT: deep venous thrombosis; CUS: compressive ultrasonography; CTPA: computed tomographic pulmonary angiography; V/Q: ventilation/perfusion.

* The suspicion for PE is made by gestalt estimate rather than using preprobability rules (eg, Wells, revised Geneva score, PE rule out criteria [PERC]), which perform poorly in pregnant patients. Similar to nonpregnant patients, any one or combination of acute-onset dyspnea, pleuritic pain, hemoptysis, syncope, or hypoxemia, particularly in the setting of a normal chest radiograph, should raise the clinical suspicion for PE during pregnancy.

¶ D-dimer becomes less useful with gestational age, such that fewer than 5% of pregnant patients with suspected PE in the third trimester have a negative D-dimer. There are no agreed-upon pregnancy-adjusted reference ranges, further limiting its use in this setting. Thus, D-dimer is less sensitive and specific than in nonpregnant patients, particularly when traditional cutoff values are used (eg, <500 ng/mL, which is the cutoff we use). When measured, we prefer high sensitivity D-dimer assays.

Δ Refer to UpToDate content on treatment of PE.

◊ While in the past V/Q scan was the preferred mode for imaging patients with suspected PE, we now use CTPA as the primary imaging modality. This preference is based upon the practical rationale that CTPA is more readily available than V/Q scanning, may provide an alternate diagnosis in 12 to 13% of cases, is associated with lower doses of radiation than in the past and has better interobserver agreement for radiologists than nuclear scans.

§ Indeterminate results are a diagnostic challenge. We either repeat testing or perform imaging that has not already been done. Magnetic resonance or contrast pulmonary angiography can be considered on a case-by-case basis but are rarely performed and poorly validated in pregnancy. In many cases, clinical judgement is required to inform therapeutic options.