Postoperative pulmonary perfusion defects: their natural history, origin and significance.

Unmatched perfusion defects occur during the early postoperative period. These defects can persist until the tenth postoperative day and their presence is not related to the transfusion of blood or to peripheral thrombosis detected by the 125I-labelled fibrinogen uptake test. It is suggested that prophylactic agents against deep venous thrombosis should be evaluated by using a combination of krypton ventilation-perfusion lung scans and 125I-labelled fibrinogen leg scans.