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 |