Case studies in perioperative management: Challenges, controversies, and common ground
ABSTRACT
This collection of case studies is designed to illustrate challenging and controversial aspects of perioperative medicine. The authors guide readers through four case narratives punctuated by practical multiple-choice questions followed by the authors’ commentary on the evidence supporting various answer choices and related considerations. The objective is to examine issues and key evidence that should inform the decision-making process in important aspects of perioperative management.
CASE 4: VENTRAL HERNIA REPAIR IN A MIDDLE-AGED WOMAN
A 60-year-old woman is scheduled for ventral hernia repair. Her medical history is unremarkable, with the exception of hypertension. She denies any bleeding problems and had no complications after a laparoscopic cholecystectomy 10 years ago. She has no family history of bleeding disorders.
Question 4.1: Would you order a prothrombin time (PT)/partial thromboplastin time (PTT)?
A. Yes
B. No
Dr. Cohn: I would not.
Dr. Sweitzer: I agree.
Question 4.2: Although not requested, a PT/PTT was ordered anyway. The PT is normal (12.2 sec/12 sec) and the PTT is abnormal (40 sec/25 sec). What is the most likely cause of the PTT abnormality?
A. Laboratory error
B. Factor VII deficiency
C. Factor IX deficiency
D. Factor XI deficiency
E. Factor XII deficiency
Dr. Cohn: The most likely cause is a sample with insufficient blood in the tube. The test wasn’t indicated in the first place, but now it must be done again.
Question 4.3: The PTT is repeated and remains abnormal: 42 sec/25 sec. Mixing studies correct the abnormality to 29 sec/25 sec. Based on this information, what is the most likely cause of the PTT abnormality?
A. Laboratory error
B. Lupus anticoagulant
C. Prekallikrein factor deficiency
D. Factor XII deficiency
Dr. Cohn: This is not a case of lupus anticoagulant because the abnormal PTT was corrected by the mixing study. Causes of a prolonged PTT include deficiencies of factors XII, XI, and IX, so factor XII deficiency is the most likely explanation, though a deficiency higher up the coagulation cascade (ie, prekallikrein factor deficiency) is possible. In the absence of any personal or family bleeding history, it is unlikely to be a deficiency of factors VII or IX (the hemophiliac) or of factor XI, so a deficiency of factor XII or one of the prekallikrein factors is more likely.
Dr. Sweitzer: A mixing study is indeed the appropriate first step. It is ordered from the lab and involves mixing the patient’s blood with normal plasma and incubating the mixture. If the mixture corrects the PTT result, as was the case with this patient, it indicates a coagulation factor deficiency in the patient’s blood; if it doesn’t correct, that should prompt evaluation for lupus anticoagulant or the presence of some other protein or hormone that’s prolonging the PTT.
Question 4.4: How would you manage this patient perioperatively?
A. Fresh frozen plasma
B. Platelet transfusion
C. Cryoprecipitate
D. Factor VII
E. No treatment necessary
Dr. Cohn: No treatment is necessary. Factor XII deficiency does not cause bleeding, regardless of the PTT. Factor XI deficiency is associated with bleeding, but usually there is a family history or a personal history of bleeding with surgery.
Screening coagulation studies are not usually indicated in a patient without a personal or family history of bleeding, liver disease, alcohol or drug use, or current anticoagulant therapy. Such studies are usually normal in such patients, and when they are not, it’s usually because of a lab error or a disease (hypercoagulable state) or factor deficiency that does not cause bleeding
Dr. Sweitzer: However, if the PTT is prolonged, the cause should be identified, because if the patient is sent to the operating room without an explanation for the prolongation, the perioperative team might think the patient has a bleeding problem and use fresh frozen plasma too readily. Fresh frozen plasma is not appropriate for everyone and may actually make a potentially hypercoagulable state worse.
