Compression ultrasonography of the legs is used to evaluate the presence of deep venous thrombosis (DVT) in the lower extremities, which can lead to the development of a pulmonary embolism (PE). The presence of a DVT demonstrated by ultrasonography is enough to warrant anticoagulation without a V/Q or spiral CT scans. The decision to administer anticoagulation therapy to a patient with a positive compression ultrasound is due to the strong association between DVT and subsequent PE. Compression ultrasonography is not the routine initial method of evaluation in a suspected PE during pregnancy unless the patient has coexisting symptoms and signs of DVT.^[1] In case the compression ultrasound is negative for DVT and there is persistent clinical suspicion of PE, the negative ultrasound does not rule out PE and additional imaging tests are required.^[1]