Diagnosing pulmonary embolism in pregnancy using computed-tomographic angiography or ventilation-perfusion.
OBJECTIVE
To estimate the rate of nondiagnosis for patients who initially undergo computed-tomographic angiography compared with those who undergo ventilation-perfusion imaging to diagnose pulmonary embolism in pregnancy.


METHODS
This was a retrospective cohort study of all women consecutively evaluated from 2001-2006 for clinical suspicion of pulmonary embolism who were pregnant or 6 weeks postpartum and underwent at least computed-tomographic angiography or ventilation-perfusion scan. Charts were abstracted for history, clinical presentation, examination, imaging, and pregnancy and maternal outcomes. Women who underwent computed-tomographic angiography for initial diagnosis were compared with women who underwent ventilation-perfusion. Primary outcome was defined as a nondiagnostic study: nondiagnostic for pulmonary embolism in the computed-tomographic angiography group, or "low or intermediate probability" in the ventilation-perfusion group. Univariable, bivariable, and multivariable analyses were performed.


RESULTS
Of 304 women with a clinical suspicion of pulmonary embolism, initial diagnosis was sought by computed-tomographic angiography in 108 (35.1%) and by ventilation-perfusion in 196 (64.9%) women. Women who underwent computed-tomographic angiography tended to have a slightly higher rate of nondiagnostic study (17.0% compared with 13.2%, P=.38). Examining the subgroup of women with a normal chest X-ray, computed-tomographic angiography was much more likely to yield a nondiagnostic result than ventilation-perfusion, even after adjusting for relevant confounding effects (30.0% compared with 5.6%, adjusted odds ratio 5.4, 95% confidence interval 1.4-20.1, P<.01).


CONCLUSIONS
Pregnant or postpartum women with clinical suspicion of a pulmonary embolism and a normal chest X-ray are more likely to have a diagnostic study from a ventilation-perfusion scan compared with a computed-tomographic angiography. Evidence supports computed-tomographic angiography as a better initial test than ventilation-perfusion in patients with an abnormal chest X-ray.


METHODS
II.
Cahill
Alison G
AG
From the Department of Obstetrics and Gynecology, and Division of Cardiovascular Imaging, Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, Missouri.
Stout
Molly J
MJ
Macones
George A
GA
Bhalla
Sanjeev
S
D000328:Adult; D000792:Angiography; D005260:Female; D006801:Humans; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis*; D011644:Puerperal Disorders / Q000175:diagnosis; D011655:Pulmonary Embolism / Q000175:diagnosis*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014692:Ventilation-Perfusion Ratio