The most common causes have been summarized in a handy mnemonic: the five W's. These tend to occur at specific days after surgery (postoperative days or POD).

• Wind, POD1-2: the lungs, i.e. pneumonia, aspiration, and pulmonary embolism, but not atelectasis
• Water, POD3-5: urinary tract infection
• Walking (or VEINS, which then sounds like "Weins"), POD4-6: deep vein thrombosis or pulmonary embolism
• Wound, POD5-7: surgical site infection, which in obstetrics or gynaecology, may refer to the Womb.
• Wonder drugs or “What did we do?”, POD7+: drug fever, infections related to intravenous lines

Numerous variants on the same theme may exist: sometimes another W for "Wonder why" may indicate an abcess somewhere in the body or the site of surgery. Of course, this list is not comprehensive: catheter-related sepsis is also frequent, but also easily recognised.

References

• Evaluating postoperative fever: A focused approach. J. Pile. Clev Clin J Med. Vol. 73, Suppl. 1, Mar 2006 (PDF file).

• Mark, K. Wax. (2004) Primary Care Otolaryngology, Chapter 3: postoperative fevers. The American Academy of Otolaryngology - Head and Neck Surgery Foundation. , 2nd edition ISBN 978-1-56772-093-8, online at http://www.entnet.org/education/primary-care.cfm