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Voiding cystourethrography in boys. Does the presence of the catheter during voiding alter the evaluation of the urethra?
Chaumoitre K, Merrot T, Petit P, Sayegh-Martin Y, Alessandrini P, Panuel M
Service d’Imagerie Medicale, Hopital Nord, Marseille, France
J Urol. 2004; 171: 1280-1

• Purpose: We determined whether the presence of the catheter during the voiding phase of voiding cystourethrography alters the evaluation of the urethra concerning the normal structures as well as pathological findings, especially posterior urethral valves.
• Materials and Methods: A total of 123 males 3 days to 16 years old (median age 2.6 months) underwent voiding cystourethrography. Urethral catheterization was performed in all cases. Four views were taken during the voiding phase with and without the catheter in place. Only 80 patients had available results. These examinations were studied with special attention to the normal structures and pathological findings.
• Results: A total of 36 examinations (45%) were normal. Pathological findings were observed in 44 patients (55%), with abnormal vesical findings and/or vesicoureteral reflux in 33 (41.25%). In 11 patients (13.75%) 12 urethral abnormalities were found (posterior urethral valves 3, hypospadias 4, prostatic utricle 1, verumontanum polyp 1, prune belly syndrome with urethral dilatation 1, imperforate anus with urethral fistula 1 and urethral duplication 1). In all cases excluding those involving hypospadias there was no difference between the views with and without the catheter. However, concerning the normal structures, the verumontanum and fossa navicularis were better delineated without the catheter in 27% and 33% of cases, respectively.
• Conclusions: Our study shows that a urethral catheter does not alter the diagnosis of abnormalities of the posterior urethra but may hamper the observation of normal structures or abnormalities of the anterior urethra.
  
  
• Editorial Comment
  Voiding cystourethrography is the most common radiologic procedure performed in children for the investigation of urinary tract infection. This article brings back an issue which has not been recently discussed (1). It is a well stablished concept among radiologysts that leaving the catheter in place during voiding cystourethrography does not prevent the diagnosis of urethral disease. The argument that the diagnosis of posterior urethral valves may be missed, due to the effacement of the valve by the catheter is not valid. The catheter should be left in place because simplifies the process of controlling contrast infusion until voiding occurs. If we remove the catheter and after that the child is not able to void, it will be necessary to do a recatheterization. Another benefit is related to technical aspects of this procedure. Voiding cystourethrography is a cyclic procedure. Reflex voiding at the beginning of vesical infusion is not uncommon. When this happens although the urethra will be promptly evaluated , the lack of adequate bladder distention may prevent the detection of vesico-ureteral reflux. By leaving the catheter in place we will be able to refill the bladder in order to perform an adequate search for reflux. After studing the posterior urethra and bladder we can always remove the catheter in order to evaluate the anterior urethra.

Reference
1. Ditchfield MR,Grattan-Smith JD, de Campo J, Hutson J: Voiding cystourethrography in boys: does the presence of the catheter obscure the diagnosis of posterior urethral valves? AJR Am J Roentgenol. 1995;164: 1233-5.

Dr. Adilson Prando
Department of Radiology
Vera Cruz Hospital
Campinas, São Paulo, Brazil