Epididymitis (/ˌɛpɪˌdɪdəˈmaɪtɪs/, ěp'ĭ-dĭd'ə-mī'tĭs, EP-i-DID-i-MEYE-tis) is a medical condition characterized by discomfort or pain of the epididymis, a curved structure at the back of the testicle in which sperm matures and is stored. Epididymitis is usually characterized as either acute or chronic: if acute, the onset of testicular pain is often accompanied by inflammation, redness, and warmth in the scrotum; if chronic, pain may be the only symptom. In either form, testicular pain in one or both testes can vary from mild to severe, and one or both epididymides may noticeably swell (inflame) and/ or harden (indurate). The pain is often cyclical and may last from less than an hour to several days.