The increasing use of computed tomography pulmonary angiography to investigate patients with suspected pulmonary embolism has led to an increase in diagnosis of small subsegmental pulmonary embolism, which is rarely detectable with nuclear medicine-based imaging, the standard imaging modality prior to the development of computed tomography pulmonary angiography. The case fatality of pulmonary embolism has fallen in line with the increase in subsegmental pulmonary embolism diagnoses from computed tomography pulmonary angiography suggesting that we may be over-diagnosing pulmonary embolism (i.e. we may be diagnosing mild forms of pulmonary embolism which may not need any treatment). Given that full anticoagulation has significant side effects of bleeding and subsegmental pulmonary embolism was not commonly diagnosed previously with nuclear medicine imaging (and therefore left predominantly untreated prior to computed tomography pulmonary angiography scanning), there is growing equipoise about the value of full anticoagulation for patients with subsegmental pulmonary embolism.
