Surgeons are often faced with the evaluation and management of groin m
asses. In most cases, an accurate history and physical examination wil
l establish a diagnosis. Ultrasonography is being increasingly used in
the evaluation of surgical problems. A case is presented in which bed
side ultrasound was utilized in the evaluation of a large, symptomatic
left inguinal mass found to be a synovial cyst on exploration. The di
fferential diagnosis of cystic groin lesions and the impact of ultraso
nography on diagnosis is reviewed with emphasis on synovial cysts. Sur
geon-directed ultrasonography is an asset in the diagnosis of some pat
ients with groin masses and may assist in the identification of those
lesions requiring prompt operative intervention.