A four-year-old boy was referred to the emergency department from his primary care physician with a four-hour history of bilateral scrotal pain, swelling, and redness. The patient had no medical or surgical history of note. On examination, the scrotum was diffusely erythematous with erythema extending to the perineum. The left hemiscrotum was enlarged and exquisitely tender to palpation. The right hemiscrotum was of normal size and mildly tender in comparison. 

The child proceeded to surgical exploration which confirmed scrotal wall edema, with normal testes and epididymides bilaterally, in keeping with acute idiopathic scrotal edema. A bilateral Jaboulay orchidopexy was performed. The child made an uneventful postoperative recovery with complete resolution of his symptoms.

Acute idiopathic scrotal edema (AISE) is a benign, self-limiting condition which is a rare cause of acute scrotal erythema. It is more common in the pediatric population than in adults.

The characteristic findings on ultrasound are those of edematous thickening and increased vascularity of the scrotal wall which produces the “fountain sign” on transverse color Doppler imaging. The testes and epididymis are normal in appearance and enlarged, hypervascular inguinal lymph nodes may be seen. Correct diagnosis can prevent unnecessary surgical exploration.