Variation in diethylenetriamine pentaacetic acid and mercaptoacetyltriglycine renal scans: clinical implications of interobserver and intraobserver differences.

PURPOSE: Diethylenetriamine pentaacetic acid and mercaptoacetyltriglycine renal scans are commonly used to evaluate infants and children with hydronephrosis to assess for changes in kidney function and drainage. We evaluate the certified nuclear medicine technologist intraobserver and interobserver variability of data processing in diuretic renal scan interpretation of the percent differential function of the right kidney so that true physiological changes can be understood by the clinician. MATERIALS AND METHODS: A total of 30 renal scans (diethylenetriamine pentaacetic acid in 20 patients and mercaptoacetyltriglycine in 10) were randomly selected for evaluation by 3 technologists who processed the scan data for each patient on 5 different occasions at least 1 week apart. Regions of interest were drawn and background areas were subtracted, and percent differential function of the right kidney was calculated. Technologists were blinded to patient identification and previous interpretation results. The data were then statistically analyzed. RESULTS: The data focused on percent differential function of the right kidney. Confidence limits for the single scan interpretation at the 95% level showed +/-5.8% differential function variation, although this scan was the same renal scan processed 1 week later. CONCLUSIONS: For differential function determined on diethylenetriamine pentaacetic acid or mercaptoacetyltriglycine diuretic renal scan the single scan 95% confidence limits were +/-5.8% differential function. From one renal scan to the next the differential percent of kidney function must change +/-11.6% differential function for a clinician to be 95% confident that a real change in kidney function has occurred. This uncertainty is substantial and is likely larger than is currently allowed for in clinical practice.

30 years of experience with York-Mason repair of recto-urinary fistulas.

PURPOSE: Recto-urinary fistula formation is a rare occurrence, usually following surgery or another intervention for prostatic disease. Spontaneous closure is rarely successful and reconstructive procedures are usually performed. We report our experience in the last 30 years with modified York-Mason repair. To our knowledge our series of 24 patients is the largest reported using this approach. MATERIALS AND METHODS: We retrospectively reviewed the medical records of all patients who underwent acquired rectourethral or rectovesical fistula repair at our institution. A total of 24 patients underwent York-Mason recto-urinary fistula repair, 18 fistulas occurred secondary to prostatic surgery and 11 patients underwent 1-stage repair without preoperative urinary or fecal diversion. RESULTS: Overall 22 of the 24 fistulas were repaired successfully using the York-Mason approach. One patient required a repeat York-Mason procedure and another required a perineal incision to correct recurrence. All except 1 fistula were eventually surgically corrected. No fecal incontinence or anal stenosis developed. The fistula involved the bladder and urethra in 11 and 13 cases, respectively. Procedure time was less than 2 hours. Blood loss was 50 to 400 cc. No transfusions were required. CONCLUSIONS: York-Mason repair of recto-urinary fistula is an excellent approach to a rare and often confounding surgical complication. It provides nice exposure through unscarred planes and allows adequate closure. The success rate is excellent compared with that of other reported techniques. Postoperative recovery is rapid with minimal morbidity.