May 5, 2009

Suspected Pulmonary Embolism in Pregnant Patient (3)

Figure: Axial CT image of the chest (PE protocol) shows filling defects (arrows) in the subsegmental branches of bilateral lower lobe pulmonary arteries in a pregnant woman at her 7-week gestation.

Second-line Imaging Tests
CT Pulmonary Angiography
  • Now accepted standard for imaging diagnosis of PE
  • In pregnant women, number of nondiagnostic CTPA may be higher than in non-pregnant population given an increased circulatory volume and altered cardiac output
  • CT venography portion should be replaced with lower extremity ultrasound to reduce radiation exposure
  • Dose reduction methods include (but not limited to): decrease mA, KVP and Z-axis coverage

Lung Scintigraphy
  • Consider in patients with normal chest radiograph and no history of asthma or COPD
  • Consider in patients with contraindication for iodinated contrast agent ie severe allergic reaction, impaired renal function
  • Dose reduction methods include (but not limited to): elimination of ventilation scan if perfusion scan negative, decrease dose of perfusion scan by half
Other Imaging Options
  • MRI without gadolinium can be performed by true fast imaging with steady-state precession, but limited evaluation to first-order pulmonary arteries
  • Conventional angiography is reserved only for unstable patients needing mechanical clot lysis, or when other tests are nondiagnostic

Pahade JK, et al. Imaging pregnant patients with suspected pulmonary embolism: what the radiologist needs to know. Radiographics 2009; 10.1148/rg.293085226 (Published online before print on March 30, 2009)

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