Approach

The clinical presentation of acute epididymitis is typically of unilateral pain and swelling of the scrotum. The most important differential diagnosis to consider is that of testicular torsion, particularly when the onset of pain is sudden and severe, and initial examination and tests show no evidence of inflammation or infection.

Clinical evaluation

History should include sexual history, risk of STIs, pre-existing lower urinary tract symptoms, and recent instrumentation.[3] These factors will allow the likely causative agents to be determined and appropriate empirical antibiotic treatment to be instigated prior to the results of diagnostic tests.

Examination may reveal a warm, erythematous, swollen hemiscrotum, with tender enlargement of the epididymis. Diffuse enlargement of the testis will be present in epididymo-orchitis. In cases of urethritis, urethral discharge and/or symptoms of dysuria may be present. In severe cases, the patient may be febrile and systemically ill. A reactive hydrocele may also be present and abscess formation may be evident by fluctuance of the swelling and induration of the overlying scrotal tissue. A digital rectal examination is recommended to assess for benign prostatic enlargement, which may suggest underlying bladder outflow obstruction and increased risk of acute epididymitis, and exclude tenderness of the prostate suggestive of concurrent acute prostatitis.

Tuberculous epididymitis may present as acute epididymitis refractory to conventional treatment.[20] Acute involvement usually disappears within 2 to 4 weeks, and as the condition evolves and becomes chronic, a hard, painless mass develops. It should be considered if no obvious other cause is determined, even if there is no known history of tuberculosis (TB) exposure.[19]

The clinical features of non-infectious epididymitis are the same as those with an infectious cause, but patients may have a history of amiodarone use or symptoms of vasculitis, such as a rash, and will not usually have a high fever or other symptoms of sepsis.

Investigations

Investigations are indicated to determine the underlying cause of epididymitis.

Where available, a urethral swab should be sent for Gram stain of urethral secretions to assess for the the diagnosis of urethritis in both symptomatic and asymptomatic males.[2][3]

A urine dipstick test that is positive for leukocytes is suggestive of infection of the lower urogenital tract, and a first-void urine sample should be sent for urine microscopy and culture. Nucleic acid amplification testing (NAAT) for Chlamydia trachomatis and Neisseria gonorrhoeae on the first-void urine sample has a higher sensitivity compared with culture, and is the preferred test for patients in whom these infections are suspected.[29][30]​​​ While culture for N gonorrhoeae is a less sensitive, alternative option to NAAT for gonorrhoea, it is the preferred option if antibiotic susceptibility testing is desired (culture for gonorrhoea requires collection of a urethral swab). Mycoplasma genitalium is diagnosed using NAAT where available.[3][31][32][33]​​ The International Union Against Sexually Transmitted Infections (IUSTI) recommends testing for M genitalium in men presenting with acute epididymo-orchitis if they are younger than 50 years.[32] Due to the fastidious nature of M genitalium, culture is difficult and antimicrobial resistance testing is limited. Molecular detection of specific resistance-mediating mutations is available in some countries.[31][32][34]​​ IUSTI-Europe recommends testing for macrolide resistance in all confirmed M genitalium cases.[32]

All patients with sexually transmitted epididymo-orchitis should be screened for other STIs including syphilis and HIV.[2][4]​​

In patients suspected of having TB, three early morning urine samples should be cultured for acid-fast bacilli and sent for NAAT for Mycobacterium tuberculosis DNA.[4][19]​​​​

Colour duplex ultrasonography is not routinely indicated for patients with suspected epididymitis, but should be done in patients with signs suggestive of abscess formation or possible testicular torsion and infarction.​​[10][35]​​[36]​​

Urgent surgical exploration may be indicated in cases where testicular torsion cannot be confidently excluded.[2][3] See Testicular torsion.​

Non-infectious causes of epididymitis are usually evident from the history of amiodarone use or underlying vasculitis and are confirmed through negative tests for bacterial infection. Idiopathic epididymitis is a diagnosis of exclusion.

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