Urinary tract infections are the scapegoat of the medical world. They make us lose our common sense, because once you find something that is easy to treat, you stop looking for anything else. This is termed satisfaction of search.
Let us look at two examples where a positive urine sample may lead the ward house officer astray, related to the domain of surgery.
Firstly, you have a patient who is POD4 after an anterior resection. You are called because they have become febrile. There is no obvious source on examination. You take cultures, and the mid stream urine comes back with a high number of white cells. You start the patient on cefuroxime for a presumed UTI. This is a frequent occurrence.
Unfortunately this decision neglects the basic rule of general surgery. This rule states that the main differentials in a febrile patient after abdominal surgery are as follows; anastomotic leak, anastomotic leak, anastomotic leak and also anastomotic leak.
“But the urine is positive!”
Unfortunately pyuria is common in intraabdominal sepsis, presumably due to the infection rubbing up against the wall of the bladder and causing inflammation. The rate of sterile pyuria in appendicitis and diverticulitis for example can be anywhere from 25% to 70-80%, depending what literature you read (1,2).
This phenomenon is not even confined to intra-abdominal infection. 30% of patients presenting with pneumonia, sepsis, intra-abdominal infection, or enteritis have pyuria (3). Of these urine samples, only 30% were culture positive. Note that culture positivity does not imply a UTI- there will be a significant proportion of asymptomatic bacteriuria.
The second situation will be when you are not on general surgery, but convincing the surgical registrar to review your patient who has abdominal pain and a clinical presentation concerning for something surgical.
“But the urine is positive, why don’t you just treat the UTI?”
Take home message? Pyuria is common in patients with other serious sources of infection and you should remind yourself and others of this.
Till next time….
- Ther Adv Urol. 2015 Oct; 7(5): 295–298. Sterile pyuria: a forgotten entity. Sanchia Goonewardene and Raj Persad
- 09 Sterile Pyuria an Indication of Acute Appendicitis in Children. S. Lewis1, C. St. Laurent1, A. Ruiz-Elizalde1 1University Of Oklahoma College Of Medicine,Oklahoma City, OK, USA
- Sterile Pyuria in Patients Admitted to the Hospital With Infections Outside of the Urinary Tract. Jared B. Hooker, MS2, James W. Mold, MD, MPH, and Satish Kumar. JABFM March 2013:97-103