Coccydyniais pain in the region of the coccyx. There are several diseases that may have clinical presentation similar to coccydynia. Here, we present a case who had tailbone trauma history and clinical presentation similar to coccydynia. The initial x-ray film showedthere was not any abnormal finding on sacrococcygeal joint or coccyx. Under ultrasound examination, we found subcutaneous edematous soft tissue with heterogeneous hypoechoic effusion collection near to coccyx. Tissue aspiration was performedlater and perianal abscesswas proven. Hence, we must keep alert to possible infectious diseases in clinical practice, and ultrasound examinationcan be a useful tool for differential diagnosis.

 coccydynia, perianal abscess, ultrasound