NEW YORK (Reuters Health) – In boys with nonpalpable cryptorchidism, performing ultrasound before surgery to localize the testes is not necessary and shouldn’t be done, two urologists from University of California, San Francisco, say.

“Eliminating the use of ultrasound in this setting will not deleteriously affect those with cryptorchidism and will not change management of the condition,” Drs. Hillary L. Copp and Gregory E. Tasian conclude in the January 2011 issue of Pediatrics, available online now. Their conclusions stem from a meta-analysis of 15 English-language studies.

Doing away with preoperative ultrasound in boys with nonpalpable undescended testes could save “tens of millions of dollars,” they say, given how often it is now performed for this indication, at an estimated cost of US$500 to $2000 per procedure.

Cryptorchidism is the most common congenital genitourinary anomaly in boys, affecting 1% to 3% of term and 15% to 30% of premature male infants. In most cases, an ultrasound is performed to locate undescended testes, especially when nonpalpable. Yet, the clinical utility of ultrasound for this purpose has never been proved, Drs. Copp and Tasian say.

To investigate, they searched the literature, identifying 15 relevant studies involving pediatric patients (696 testes) who had preoperative ultrasound evaluation for nonpalpable testes and whose testis position was determined by surgery. Eight studies were prospective, six were retrospective, and one did not provide enough details to determine study design.

For their meta-analysis the authors included only 12 of the studies (591 testes). The clinicians found that ultrasound before surgery for undescended testis performed poorly as a diagnostic test. It had a composite sensitivity and specificity in localizing a nonpalpable undescended testis of 45% and 78%, respectively. The composite likelihood ratios for a positive and negative ultrasound result were 1.48 and 0.79, respectively.

“Even using the most generous estimates of ultrasound performance, ultrasound does not reliably localize nonpalpable testes,” they say. It can’t differentiate nonviable nubbins from surrounding inguinal tissue, and bowel gas often precludes localization of intraabdominal testes, they found

If ultrasound could reliably determine the presence and location of a nonpalpable testis, a child could be spared an operation (if the testis was absent) or could undergo a more limited operation restricted to where the testis was seen on ultrasound. However, based on their analysis, ultrasound does not have the diagnostic power to do this.

Moreover, they note that relying on ultrasound findings in undescended testes could have harmful consequences. For example, if a urologist decides not to operate on a child with a nonpalpable testis that is not seen on ultrasound, there is still, by conservative estimates, a 36% chance that the testis is within the abdomen. Leaving it there potentially increases the child’s risk of testicular carcinoma.

Reference:

Diagnostic Performance of Ultrasound in Nonpalpable Cryptorchidism: A Systematic Review and Meta-analysis

Pediatrics 2011;127:119-128.