Preoperative hemostatic evaluation: which tests, if any?

W HEN THE WHOLE BLOOD clotting time and the Duke bleeding time were the tests used to screen hemostatic function preoperatively, the question posed in the title of this brief review was easy to answer: Do not bother with these insensitive tests, rely on the patient’s history. However, the reliability today of screening techniques that can detect virtually all patients with hemostatic abnormalities has changed the answer and rendered it more complex. One may logically ask: If the history alone was good enough before, why not now’? There are four reasons for advocating tests in addition to the history. First, they may protect against the doctor who fails to take an adequate history. ln my city, a patient who was defibrinating from metastatic prostatic carcinoma bled to the point of requiring transfusions after an elective biopsy of the ear performed by a doctor concerned only with the patient’s minor skin problem. Second, some patients give an unreliable history, e.g., the patient with a mild bleeding disorder who does not realize that the bleeding he or she has experienced after trauma or surgery is excessive. Third, a patient may have an abnormality, such as factor XI deficiency, that causes bleeding only after surgery and may not yet have had surgery or dental extractions. Finally, a patient who has withstood surgery without abnormal bleeding may later acquire a hemostatic defect, such as thrombocytopenia, that has remained asymptomatic. Screening tests, therefore, have a role in preoperative evaluation, a role determined by a general evaluation of the patient’s clinical status, by the information obtained from a screening bleeding history, and by the type of surgery planned. Consequently, it is important that doctors and their institutions develop a standardized procedure for taking a screening history on all preoperative patients. A simple screening questionnaire, which most patients should be able to complete while waiting to be seen, can be designed from the following questions: