UROLOGICAL SURVEY   ( Download pdf )

 

PEDIATRIC UROLOGY

Routine voiding cystourethrography is of no value in neonates with unilateral multicystic dysplastic kidney
Ismaili K, Avni FE, Alexander M, Schulman C, Collier F, Hall M
Department of Perinatal and Pediatric Nephrology, Hopital Universitaire des Enfants-Reine Fabiola and Hopital Erasme, Brussels, Belgium
J Pediatr. 2005; 146: 759-63

  • Objectives: To determine if two successive ultrasound examinations could rule out the presence of clinically significant contralateral anomalies in neonates with multicystic dysplastic kidney (MCDK), thereby avoiding unnecessary voiding cystourethrography (VCUG).
  • Study Design: We followed 76 newborn infants with antenatally discovered MCDK. Two successive neonatal renal ultrasound examinations were performed, one within the first week and one at around 1 month of life. VCUG and isotopic studies were performed in all infants.
  • Results: Urologic anomalies of the contralateral kidney were present in 19 of 76 children (25%): vesicoureteral reflux (VUR) in 16 (21%), ureteropelvic junction obstruction in 2 (3%), and renal duplex kidney in 1 (1%). Sixty-one infants (80% of total) had normal contralateral urinary tract on the 2 successive neonatal renal ultrasound scans. Among them, 4 of 61 (7%) infants presented with low-grade VUR on VCUG that had resolved spontaneously before 2 years of age. The sensitivity, specificity, positive predictive value, and negative predictive value of two successive ultrasound scans in the neonatal period to predict contralateral urological anomalies on VCUG were 75%, 95%, 80%, and 93%, respectively.
  • Conclusions: In infants with antenatally diagnosed MCDK, two successive normal neonatal renal ultrasound scans will rule out clinically significant contralateral anomalies, thereby rendering the need for a neonatal VCUG unnecessary.

  • Editorial Comment
    The authors reviewed retrospectively their experience since 1990 with prenatally diagnosed multicystic kidney disease. They look specifically at the need for a VCUG. They show that about 21% of patients had reflux. This number is comparable to that seen in the literature. Mostly the reflux was low grade, although 7 of 16 had reflux of Grade III, IV or V. The authors show that all cases of high grade reflux, and most of those with low grade reflux, had an abnormal ultrasound. They propose that VCUG should not be done routinely; only when the ultrasound is abnormal.
    This is an interesting and somewhat controversial proposal. In general, little severe pathology occurs in the contralateral kidney of a neonate with an isolated multicystic kidney, making the author’s proposal attractive. On the other hand, the authors provide no data on the use of prophylactic antibiotics and the rate of urinary tract infection (either with or without antibiotics). Although I intuitively agree with the concept, the data behind the proposal are, in my mind, limited. If they demonstrated that there were no UTIs, even without antimicrobials, this would provide data that diagnosing reflux is truly unimportant in the great majority of cases.
    An even more interesting question is the cost-benefit of annual ultrasound examinations. Presumably, these are performed in order to follow the size of the kidney and to rule out a neoplasm. On the other hand, the size of the kidney is largely irrelevant and in the absence of symptoms (extremely rare), there is little need to know the size. Moreover, the disease does not exist in adulthood; hence, virtually all multicystic kidneys must involute over time. Neoplasm is vanishingly rare and even in that rare instance; will an annual ultrasound pick it up in reasonable time? Hence, on theoretical grounds, annual ultrasound is unnecessary. A formal study of this would be valuable.

Dr. Barry A. Kogan
Chief and Professor of Urology and Pediatrics
Albany Medical College
Albany, New York, USA