The usefulness of ultrasound examination in detecting testicular nubbin in Japanese boys with non-palpable testes.
INTRODUCTION AND OBJECTIVE
In the case of non-palpable testes, we often find a small nodule which is called "testicular nubbin (TN)" in scrotum or inguinal canal. There is no agreement about the treatment for TN. This time we investigated whether or not ultrasound examination (US) can be a useful modality for detecting TN.


MATERIALS AND METHODS
We recruited 66 boys who were diagnosed with non-palpable testes and who had undergone US studies. We examined age, affected side, size of the unaffected side, presence of testicular hypertrophy, and findings from US studies. Radiologists or sonographers familiar with examination of testicular nubbin carried out the ultrasound studies. When TN is detected in a patient, preservation or excision of the TN was chosen by their families.


RESULTS
Sixty-six boys and 76 testes were examined. Thirty-four testes (44.7%) were diagnosed as having TN, 39 (51.3%) were undescended testes, and 3 (3.9%) were retractile testes. The median age of all participants was 13 months (range: 2-118 months). The mean ages of patients with TN, undescended testes, and retractile testes were 7.6 months, 14.5 months and 55 months, respectively. The size ratio between the affected and unaffected sides in cases of TN was 0.144 (range; 0.03-0.48) and in cases of undescended testes was 0.99 (0.46-1.2). Thirty cases of TN (88.2%) had testicular hypertrophy on the unaffected side. Only one case of TN underwent excision; viable cells were not seen. A high US region was observed in 31 (91.1%) cases with TN.


CONCLUSION
US was a useful modality for detecting TN. From this study, TN can be detected if the size ratio between the affected and unaffected sides is < 0.4 and a high US region is seen. If TN can be detected using US, preservation can recommended, preventing unnecessary surgeries. However, there is no evidence on the required duration and interval of follow-up for these cases and examination will be needed over a period of time.