BACKGROUND:
Since it’s conception in the early 1970s, the Whitaker test (WhT) has been used to guide urologic intervention in cases of suspected urinary obstruction. Although the diuretic renal scan is regarded as highly specific for obstruction, in certain cases the test is inconclusive or additional information is warranted. Given its status as a nuanced modality that requires a knowledgeable radiology team and support staff, guidance on situations to utilize the WhT in capable facilities is warranted. This study aims to highlight the utility of the Whitaker test in a modern cohort.
METHODS:
A retrospective chart review was performed on 26 patients who underwent 27 Whitaker tests from 2019-2022 at a tertiary referral center for pediatric urology. Variables examined included interpretation of renal scan by radiologist, pre- and post-WhT interventions, reason for performing a WhT, prior nephrostomy tube placement, and pediatric urologist interpretation of renal scans.
RESULTS:
Mean age at time of WhT was 41 months (range 1-235, median 67); 70% (18/26) male. 14 (54%) of these patients had no prior intervention, but 12 (46%) patients had a prior pyeloplasty or ureteral reimplantation. Eleven patients (42%) had a nephrostomy tube in place prior to WhT with the most common reason for placement being pyelonephritis (4/11, 36%). Of the 27 diuretic renal scans performed prior to WhT, 7 (26%) were read as inconclusive by a radiologist. Of these patients, 6 (86%) interventions were based on the results of a WhT. Of the 22 renal scans with a definitive diagnosis as read by a radiologist, results of the WhT differed in six (27%). In four of these patients (66%), interventions were based on the results of the WhT. Of the 25 reviewable pre-Whitaker renal scans, only one (4%) showed unanimous agreement on interpretation among seven fellowship-trained pediatric urologists.
CONCLUSIONS:
In patients with an inconclusive or equivocal renal scan, the WhT remains a valuable diagnostic tool and altered the treatment in the majority of these patients. The WhT is not always concordant with renal scan results, and often seems to assist with management in these cases. The small percentage of agreement in renal scan interpretation in these patients highlights the utility of the Whitaker test as an additional data point.
