Urine Specimens from Foley and Suprapubic Catheters
When to test, whether to replace the catheter first, where the specimen comes from, and the one place it must never come from.
A urine culture drawn the wrong way produces an organism that was living on the catheter rather than causing the patient's symptoms. The patient is then treated for the wrong thing, or treated when they did not need treating at all.
Test only when there is a reason
Obtain a UA or culture only when the patient has appropriate signs and symptoms, or there is another clinical indication for testing.
A catheterised patient will grow organisms. Culturing without a clinical reason finds them, and finding them invites treatment that the patient did not need.
If a UTI is suspected
Per CDC guidance:
Catheter in place more than 14 days
Replace the catheter before obtaining the specimen — when clinically appropriate, and when the catheter is still indicated.
Then obtain the UA and culture from the newly inserted sterile catheter, using aseptic technique.
Catheter does not need replacing
Obtain the specimen from the sterile sampling port, after properly disinfecting the port.
Never disconnect the closed system.
Never, in any circumstance
Never obtain a urine culture from the drainage bag.
Bag urine has been sitting, at room temperature, in a container that is not sterile. Whatever grows from it tells you about the bag.
Why the fresh catheter matters
An indwelling catheter develops a biofilm over time. That biofilm has its own population of organisms, and a specimen drawn through it reflects the biofilm rather than the bladder.
The result is an inaccurate identification of the organism actually causing the patient's symptoms — so the antibiotic chosen may not treat what the patient has.
Do not change a catheter just to get a specimen
Do not change a catheter routinely, or solely for the purpose of obtaining a UA, when there is no clinical indication for replacement.
Catheter changes are based on clinical indications:
- Suspected infection
- Obstruction
- A compromised closed system
Routine monthly changes and their ordering requirements are on Plotting Visits.
Document it
- The clinical indication for testing — the signs and symptoms that prompted it
- The catheter change, if one was done
- That the specimen was obtained from the newly placed catheter, or from the disinfected sampling port
- Date and time of collection
- Who the result goes to, and who is chasing it
That third item is the one people leave out, and it is the one that tells whoever reads the culture how much to trust it.
Before you leave the home
- Right container for the receiving lab — Saint Luke's and Quest differ. See Lab Tube Cheat Sheet.
- Labelled at the bedside
- Transported per policy
- Follow-up planned — see Labs, Specimens, and Results Follow-Up
- If an antibiotic is started, an infection log is required — see Infection Control and the Infection Log
Why this matters beyond one patient
Collected properly, a culture answers a question. Collected from a drainage bag or through two-week-old biofilm, it manufactures one — and the patient gets an antibiotic they may not need, for an organism they may not have.
Following the collection practice is how the agency reduces contamination and unnecessary treatment.