Hydronephrosis

Hydronephrosis incontinence of 1.5. Only stress and mixed-type incontinence were significantly associated with cesarean sections. The adjusted OR for any incontinence associated with vaginal deliveries compared with cesarean sections was 1.7. Only stress incontinence (adjusted OR, 2.4) was associated with the mode of delivery. Results of this study demonstrated that women who delivered vaginally had a 2- to 3-times higher risk of stress incontinence compared with nulliparous women, whereas those who delivered by cesarian section had a 50% higher risk. Other interesting findings were that urge incontinence is not associated with childbirth and that even nulliparous women can develop stress urinary incontinence. However, urologists should not interpret the study as indicating cesarean sections if one wants to prevent incontinence. Hydronephrosis Dynamic Contrast-Enhanced Magnetic Resonance Imaging for the Evaluation of Hydronephrosis in Children Reviewed by Ellen Shapiro, MD, FACS, FACP Department of Urology, New York University School of Medicine, New York, NY [Rev Urol. 2004;6(1):49-50] © 2004 MedReviews, LLC ydronephrosis is detected on 1 in 800 to 1500 prenatal sonograms. Most mild grades of dilation resolve spontaneously. Because there is no test that absolutely defines obstruction, moderate-to-severe grades of hydronephrosis pose a diagnostic dilemma for both pediatric urologists and pediatric radiologists. To date, most pediatric urologists employ a combination of sonography, radionuclide scintigraphy, and voiding cystourethrography to elucidate the cause and severity of the hydronephrosis. In previous studies, magnetic resonance imaging (MRI) has been used to evaluate acute pyelonephritis, vesicoureteral reflux, and renal function. In the article below, investigators from Emory University utilized dynamic contrast-enhanced MRI to investigate the pediatric urinary tract. The technology of magnetic resonance urography has continued to evolve, incorporating newer imaging sequences and shorter H acquisition times. Together, these studies demonstrate that MRI has the ability to clearly define normal versus abnormal renal anatomy. A Prospective Study Comparing Ultrasound, Nuclear Scintigraphy and Dynamic Contrast Enhanced Magnetic Resonance Imaging in the Evaluation of Hydronephrosis Perez-Brayfield MR, Kirsch AJ, Jones RA, Grattan-Smith JD. J Urol. 2003;170(4 pt 1):1330-1334. This study compared dynamic contrast-enhanced MRI with other imaging modalities used to evaluate pediatric hydronephrosis. A total of 100 dynamic contrast-enhanced MRIs were performed in children, all of whom had also undergone renal/bladder sonography. Additional imaging modalities employed included 99mtechnetium-diethylenetriamine pentaacetic acid (DTPA) in 39 subjects, 99mmercaptoacetyltriglycine (MAG-3) in 29 subjects, 99mtechnetium-dimercaptosuccinic acid (DMSA) in 3 subjects, and voiding cystourethrography (VCUG) in 64 subjects. Older patients with no history of urinary tract infection did not undergo VCUG. The MRI was performed within 6 months of the other examinations. Of 96 children (girls [n = 35], boys [n = 61]; mean age, 4 years [range, 1 month to 17 years]), 4 subjects underwent MRI after 6 months; only 9 studies were performed postoperatively. Sedation was performed with chloral hydrate in patients younger than 1 year and intravenous pentobarbital plus fentanyl in older patients; there were no complications associated with sedation. The MRI technique evolved over the study period. However, the last 80 patients followed the same standard protocol, which was similar to that used with nuclear scintigraphy. This protocol included catheter drainage, hydration, and administration of furosemide. GadoliniumDTPA was injected, and sequential images revealed perfusion, uptake, and excretion phases. The renal volume was calculated to determine the differential renal function. Threedimensional maximal intensity projections, which provide anatomical detail similar to an intravenous pyelography, were obtained from delayed images. The most common presentations of study subjects were prenatal hydronephrosis (n = 43) and urinary tract infection (n = 22). The final MRI diagnoses in the 96 subjects were ureteropelvic junction obstruction (n = 26), ureterovesical junction obstruction (n = 14), dilation without obstruction (n = 35), duplex system (n = 13; nonfunctioning upper pole [n = 3], ectopic ureter [n = 5], normal duplication [n = 1]), multicystic kidney (n = 5), small scarred kidney (n = 1), pyelonephritis (n = 2), renal mass (n = 1), bilateral polycystic VOL. 6 NO. 1 2004 REVIEWS IN UROLOGY 49 Hydronephrosis continued kidneys (n = 1), and normal (n = 9). In all cases, MRI produced anatomical images that were superior in spacial and contrast resolution to those of other upper tract imaging modalities. With MRI, the ureters were visualized throughout their course down to the level of the bladder or their ectopic insertions. The correlation coefficient for split renal The correlation coefficient for split renal function using nuclear medicine versus MRI was 0.93. function using nuclear medicine versus MRI was 0.93. A diagnosis of obstruction using ultrasound and nuclear medicine was correlated with the MRI final diagnosis in 78% of studies. Of the 14 cases that did not correlate, 8 showed obstruction on MRI only and 5 showed obstruction on the nuclear medicine study only. One patient who was thought to have ureteropelvic junction obstruction was found to have ureterovesical junction obstruction on MRI. One patient whose MRI and nuclear medicine study sug- 50 VOL. 6 NO. 1 2004 REVIEWS IN UROLOGY gested obstruction showed only partial obstruction on a retrograde pyelogram. This study represents the largest examination of pediatric patients using dynamic contrast-enhanced MRI for the evaluation of hydronephrosis. There are, however, some innate problems in the investigation. Although the population and study protocol were not homogeneous, all persons undergoing MRI were included in the report. This does not permit definitive conclusions to be drawn. In addition, there were 5 patients in whom obstruction was seen only on the nuclear medicine study; however, this may have been due to improvement in the hydronephrosis during the 6-month period before the MRI was performed. In summary, dynamic contrast-enhanced MRI appears to provide superior anatomic detail compared with sonography and nuclear scintigraphy. The procedure delivers no ionizing radiation to the infant or child but does require sedation in all cases. In addition, it is equivalent to nuclear medicine in evaluating split renal function and obstruction. Because of the significant cost of the procedure, dynamic contrastenhanced MRI is not yet available at all facilities.