Differentiation of epididymitis and appendix testis torsion by clinical and ultrasound signs in children.

Objective: To identify the signs that can help to differentiate torsion of the appendix testis (AT) and epididymitis and to establish the incidence of the various pathologic entities in boys with an acute scrotum.

Materials And Methods: A retrospective study was performed of the data from all boys treated at our institute from January 2008 to January 2012 for the diagnosis of an "acute scrotum." The clinical and, if available, ultrasound findings were documented. Differences between groups were calculated using a chi-square test or analysis of variance and classification and regression tree analysis.

Results: A total of 241 boys with acute scrotal pain were included and underwent surgical exploration. Of the 241 boys, 163 (70%) had AT, 44 (18.5%) had epididymitis, 31 (13.3%) had testicular torsion, and 3 (1.3%) had idiopathic scrotal edema. The incidence of AT was significantly increased in the colder months (P = .01). We found that AT and epididymitis shared several aspects but differed regarding dysuria (epididymitis, P ≤.001), a painful epididymis on palpation (epididymitis, P = .028), increased epididymal echogenicity (epididymitis, P = .043), augmented peritesticular perfusion (epididymitis, P = .05), and a positive blue dot sign (AT, P <.001). The classification and regression tree analysis showed that the presence of dysuria, a positive blue dot sign, and a painful epididymis are the best factors for distinguishing AT and epididymitis.

Conclusion: Most children with an acute scrotum will have AT or epididymitis. It will be possible to differentiate most cases using the clinical and ultrasound findings. In our study, the best predictors were dysuria, a painful epididymis on palpation, and altered epididymal echogenicity and increased peritesticular perfusion found on ultrasound studies for epididymitis and a positive blue dot sign for AT.