Obtaining Urinalysis in Anuric Patients
For patients with anuria, a catheterized specimen is the recommended method to obtain a urinalysis sample, with the catheter changed if an indwelling catheter is present and the sample collected after allowing for urine accumulation while temporarily plugging the catheter. 1
Methods for Obtaining UA in Anuric Patients
In patients with indwelling catheters, obtain the urine culture specimen after changing the catheter and allowing for urine accumulation by temporarily plugging the catheter. Never collect urine from the extension tubing or collection bag as this can lead to contamination. 1
For patients without indwelling catheters who are truly anuric, a catheterized specimen may be the only option to obtain even a small amount of urine for analysis. 1
In female patients, a catheterized urinary specimen is indicated if a clean-catch specimen cannot be reliably obtained due to vaginal contamination, obesity, or anuria. 1
For uncircumcised men with phimosis who are anuric, a catheterized urinary specimen may be required. 1
Clinical Considerations for Anuric Patients
Recognize that true anuria (urine output less than 100 mL/day) may indicate severe renal dysfunction, and obtaining even small amounts of urine may be challenging. 1
Be aware that anuria can be caused by various conditions including acute kidney injury, obstructive uropathy, or end-stage renal disease. 2
Consider that patients on peritoneal dialysis who become anuric (defined as urine output less than 100-200 mL/day) will have limited urine available for sampling. 1
In patients with suspected urinary tract infection who are anuric, the clinical presentation may be atypical, and obtaining even a small sample for culture is important before initiating antibiotics. 1
Interpretation Challenges in Anuric Patients
Urinalysis results in anuric patients may be more concentrated and should be interpreted with caution. 3
In patients requiring clean intermittent catheterization (CIC) with minimal urine output, a negative leukocyte esterase test has a high negative predictive value for UTI. 4
Be aware that relying on voided specimens in patients with low urine output may lead to overdiagnosis of UTIs; catheterized specimens are more reliable. 5
When to Perform UA in Anuric Patients
Do not perform routine surveillance/screening urine testing, including urine culture, in asymptomatic patients with neurogenic lower urinary tract dysfunction who may have minimal urine output. 1
Obtain urinalysis and urine culture in patients with signs and symptoms suggestive of a urinary tract infection, even if urine output is minimal. 1
In patients with concomitant hematuria, recurrent urinary tract infections, or suspected anatomic anomaly (e.g., strictures, false passage), perform cystoscopy in addition to obtaining a urinalysis. 1
Special Situations
In patients with anuria due to acute kidney injury, even a small sample obtained via catheterization may provide valuable diagnostic information. 6
For patients with reflex anuria (a rare condition where unilateral ureteral obstruction causes contralateral kidney shutdown), obtaining a urine sample may require relief of the obstruction first. 2