Study objective: In patients with proven acute pulmonary embolism (PE), a systematic search for “residual” deep vein thrombosis (DVT) using venography or compression duplex ultrasonography (CDUS) of the lower limbs is negative in 20 to 50% of patients. We hypothesized that undetectable pelvic vein thrombosis (from the external iliac vein to the inferior vena cava) could account for a substantial proportion of patients with negative CDUS findings. Using a noninvasive test, magnetic resonance angiography (MRA), the objective of the study was to assess the prevalence of pelvic DVT in patients with acute PEs and normal findings on lower limb CDUS.
Design: Prospective study. Setting: A 35-bed respiratory unit in a 680-bed Parisian teaching hospital.
Patients: From June 1995 to October 1996, 24 patients (mean age, 49 years; age range, 18 to 83 years) with acute PEs and normal findings on lower limb CDUS underwent pelvic MRA.
Measurements and results: MRA disclosed pelvic DVT in seven patients (29%). The common iliac vein was involved in five patients. Internal iliac vein (hypogastric) thrombosis was imaged in two patients, but no patients had DVT limited to this vein. Three patients underwent subsequent venography studies that confirmed the MRA findings. In three other patients, a new MRA at the end of anticoagulant therapy showed the resolution of the DVT.
Conclusions: Our data support the view that, among patients with negative findings on CDUS, a substantial proportion of the DVTs that are responsible for PE originates in the pelvic veins. This study provides additional arguments to suggest that MRA might become the reference test for the exploration of pelvic DVT.