1. Which of the following is not a cause of post operative fever on the second week following surgery?
   
1. Deep venous thrombosis
2. Central venous catheter infection
3. Febrile drug reactions
4. Inflammation due to tissue injury caused by the surgery.

Answer: Deep venous thrombosis is an important cause of subacute post operative fever. Central venous catheter infections and febrile reactions to drugs like penicillin group of antibiotics and sulfa drugs can also cause subacute fever. The only reason which is highly unlikely to present as a late fever in the post operative period is tissue trauma induced inflammatory reaction. So the answer is (d)