Does epididymitis always show up on ultrasound and Urinalysis (UA)?

From the Guidelines

Epididymitis does not always show up on ultrasound or urinalysis (UA). While scrotal ultrasound examination is recommended for the diagnosis of epididymitis, as seen in the European Association of Urology guidelines on urological infections 1, it may not detect all cases, especially early or mild ones. The guidelines suggest a clinical assessment and the use of midstream urine for culture, urethral swab/smear, and first voided urine for nucleic acid amplification test (NAAT) for diagnosis, indicating that ultrasound is just one part of the diagnostic process.

Some key points to consider in the diagnosis of epididymitis include:

• Clinical assessment is crucial, focusing on symptoms like scrotal pain, swelling, and tenderness, often accompanied by fever.
• Ultrasound can detect epididymal enlargement, increased blood flow, and hydrocele, but its sensitivity ranges from 70-95% depending on the severity and duration of symptoms.
• Urinalysis may show signs of infection such as white blood cells, bacteria, or nitrites in cases where epididymitis is caused by bacterial infection, but can be normal in non-infectious or viral epididymitis.
• If epididymitis is suspected despite normal imaging and lab results, empiric treatment may still be appropriate, typically with antibiotics such as ceftriaxone 1000 mg i.m. or i.v. plus a course of an antibiotic active against Chlamydia trachomatis, as recommended by the guidelines 1.
• Additional testing like STI screening should be performed regardless of UA results in sexually active patients, as suggested by the guidelines 1.

From the Research

Epididymitis Diagnosis

• Epididymitis may not always show up on ultrasound and urinalysis (UA) as the sensitivity and specificity of these diagnostic tests can vary 2.
• The sensitivity of urinalysis for epididymo-orchitis was found to be 58.2%, while the specificity was 85.1% 2.
• Ultrasound had a sensitivity of 78.8% and a specificity of 98.1% for the diagnosis of epididymo-orchitis 2.

Ultrasound Findings

• Common ultrasound features of acute epididymitis include hydrocele, epididymal enlargement, hyperperfusion, and testicular involvement 3.
• Epididymitis was predominantly located in the head, tail, or both, with 43.3% of cases affecting both areas 3.
• Concomitant orchitis was associated with hydrocele, testicular enlargement, and pain 3.

Urinalysis Utility

• The reflexive ordering of a urinalysis in patients with scrotal pain may be unnecessary, as it only changed management in 5.2% of cases 2.
• Urinalysis may occasionally provide some benefit in the evaluation of patients with suspected epididymo-orchitis, but its utility is limited compared to ultrasound 2.

Diagnostic Approach

• The diagnosis of patients who present to the emergency department with scrotal pain is primarily driven by the ultrasound results 2.
• A comprehensive diagnostic approach, including physical examination, laboratory tests, and imaging studies, is necessary to accurately diagnose and manage epididymitis 4, 5, 6.