Acute scrotal pain can be caused by several entities. At the top of the differential diagnosis should be acute testicular torsion, as this represents a surgical emergency requiring prompt urologic evaluation and surgical exploration. Torsion of an epididymal or testicular appendage can mimic testicular torsion; however, certain history, physical exam, and imaging findings can help differentiate this diagnosis. For example, in prepubertal boys, torsion of an epididymal or testicular appendage is one of the most, if not the most, common cause of an acute scrotum. Additionally, nausea and vomiting are less prevalent in epididymal or testicular appendage torsion than in patients with testicular torsion. Physical exam findings suggestive of epididymal or testicular appendage torsion include focal tenderness at the superior pole of the testis/epididymal head as well as the presence of the "blue-dot" sign. On testicular ultrasound with color Doppler evaluation, normal blood flow should be present in the testis, with the presence of an oval or round hypovascular lesion located at the upper pole of the testis by the head of the epididymis. The treatment for this condition is conservative, with rest, ice, and NSAIDs. Pain can persist for a week or two. Patients with continued pain may require elective surgery for excision of the appendage to completely relieve symptoms, though this is rare.
See Scrotal Pain in The Manual for more details.
References:
Boettcher M, Bergholz R, Krebs TF, et al. Differentiation of epididymitis and appendix testis torsion by clinical and ultrasound signs in children. Urology 2013;82:899-904.
Lev M, Ramon J, Mor Y, Jacobson JM, Soudack M. Sonographic appearances of torsion of the appendix testis and appendix epididymis in children. J Clin Ultrasound 2015;43:485-9.
Ringdahl E, Teague L. Testicular torsion. Am Fam Physician 2006;74:1739-43.