Ultrasound is frequently obtained during the presurgical evaluation of boys with nonpalpable undescended testes, but its clinical utility is uncertain.
To determine the diagnostic performance of ultrasound in localizing nonpalpable testes in pediatric patients.
English-language articles were identified by searching Medline, Embase, and the Cochrane Library. We included studies of subjects younger than 18 years who had preoperative ultrasound evaluation for nonpalpable testes and whose testis position was determined by surgery. Data on testis location determined by ultrasound and surgery were extracted by 2 independent reviewers, from which ultrasound performance characteristics (true-positives, false-positives, false-negatives, and true-negatives) were derived. Meta-analysis of 12 studies (591 testes) was performed by using a random-effects regression model; composite estimates of sensitivity, specificity, and likelihood ratios were calculated.
Ultrasound has a sensitivity of 45% (95% confidence interval [CI]: 29–61) and a specificity of 78% (95% CI: 43–94). The positive and negative likelihood ratios are 1.48 (95% CI: 0.54–4.03) and 0.79 (95% CI: 0.46–1.35), respectively. A positive ultrasound result increases and negative ultrasound result decreases the probability that a nonpalpable testis is located within the abdomen from 55% to 64% and 49%, respectively. Significant heterogeneity limited the precision of these estimates, which was attributable to variability in the reporting of selection criteria, ultrasound methodology, and differences in the proportion of intraabdominal testes.
Ultrasound does not reliably localize nonpalpable testes and does not rule out an intraabdominal testis. Eliminating the use of ultrasound will not change management of nonpalpable cryptorchidism but will decrease health care expenditures.
In this systematic review and meta-analysis of the use of ultrasound (US) in the evaluation of patients with non-palpable undescended testicles (NPUDT). The authors conclude that US does not reliably localize NPUDT and question whether pre-operative US changes the operative approach. In all but one of the studies included in the meta-analysis the same operative approach was performed regardless of the US findings.
Our findings have been similar to those of this study and agree that when no gonad is seen on US the next step is for either surgical exploration or diagnostic laparoscopy so as not to miss an intra-abdominal or inguinal testicle that may not have been felt on physical examination. Our approach, however differs when it comes to the overweight patient and find US to be very valuable in this group of patients. We prospectively evaluated all patients with a NPUDT over a ten year period. Patients were divided into 4 groups based on body mass index (BMI). All patients had pre-operative US followed by either laparoscopy or groin exploration and in some cases both. If a testicle was seen in the groin on US, laparoscopy was not performed. If a gonad was not seen on US, the patient underwent laparoscopy and groin exploration to confirm lack of testicular tissue. Negative predictive values(NPV) for US was 100%, 97%, 95% and 90% for groups 1-4 respectively, whereas it was only 93%, 85%, 75% and 64% for physical examination. The NPV of US in identifying the NPUDT remains high even in overweight patients in whom physical examination is often difficult and unreliable. Diagnostic laparoscopy with it's associated increased difficulty and complication rate in overweight patients, can be avoided when US identifies the presence of an inguinal or even low abdominal testicle. Our recommendation is for continued use of US in overweight patients where the sensitivity of physical examination remains low and if seen will save the patient an unnecessary laparoscopy.
Conflict of Interest:
None declared