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Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find the Epididymo-orchitis article more useful, or one of our other health articles.

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What is epididiymo-orchitis?

Acute epididymo-orchitis is a clinical syndrome consisting of pain, swelling and inflammation of the epididymis, with or without inflammation of the testes. The most common route of infection is local extension and is mainly due to infections spreading from the urethra (sexually transmitted infections (STIs)) or from the bladder.1 Orchitis (infection limited to the testis) is much less common. Chronic epididymitis refers to epididymal pain and inflammation (usually without scrotal swelling) that lasts for more than six months.

Epididymo-orchitis causes (aetiology)1 2

  • In men under 35 years old, infection is most often due to a sexually transmitted pathogen - eg, Chlamydia trachomatis and Neisseria gonorrhoeae.

  • In men over 35 years old, infection is most often due to a non-sexually transmitted Gram-negative enteric organism causing urinary tract infections - eg, Escherichia coli, Pseudomonas spp. Specific risk factors include recent instrumentation or catheterisation.

  • However, there is an overlap between these groups and a thorough sexual history is imperative for all age groups.

  • Extrapulmonary tuberculosis (TB) represents 40-45% of TB cases in the UK but tuberculous epididymo-orchitis is a rare presentation. It is likely to present in patients from high-prevalence countries or with a previous history of TB and particularly in patients with immunodeficiency. It is usually a result of disseminated infection and commonly associated with renal TB but can be an isolated finding.

  • Ureaplasma urealyticum is found in men with epididymo-orchitis, often in association with N. gonorrhoeae or C. trachomatis infection.

  • 12-19% of men with Behçet's disease develop epididymo-orchitis. This is non-infective and thought to be part of the disease process. It is associated with more severe disease.

  • Other rare infections (eg, brucellosis, coccidioidomycosis, blastomycosis, cytomegalovirus and candidiasis) usually occur in immunocompromised hosts.3

  • Epididymo-orchitis has also been reported as an adverse effect of amiodarone but this is a rare side-effect of amiodarone.4

Causes of acute orchitis (aetiology)5

  • Viral: mumps orchitis is most common. Coxsackievirus A, varicella and echoviral infections are rare.6 7

  • Bacterial and pyogenic infections (E. coli, Klebsiella, Pseudomonas, Staphylococcus and Streptococcus species) are unusual.8

  • Granulomatous (syphilis, TB, leprosy, Actinomyces spp. and fungal diseases) are rare.1 9 10

  • Trauma.

  • Idiopathic.

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How common is epididymo-orchitis? (epidemiology)

  • Epididymitis is a common condition with incidence ranging from 25-65 cases per 10,000 adult males per year, and can be acute, chronic or recurrent.11

  • Acute epididymitis most commonly occurs in patients aged 15-35 years and patients older than 60 years.

  • Prepubertal epididymitis is much less common (and testicular torsion is much more common in this age group). However, prepubertal epididymitis is thought to be more common than was once believed. It is thought to be a postviral infectious phenomenon.12

  • Mumps orchitis occurs in up to 40% of postpubertal boys with mumps; it is rare in prepubertal boys.13 An outbreak starting in 2004 and lasting for some three years was seen in England and Wales and was attributed to a reduction in the uptake of measles-mumps-rubella (MMR) vaccine during the early to mid-1990s in children who subsequently matured.14

  • Testicular tuberculosis is rare and the diagnosis is frequently delayed or may be missed.15

Risk factors1 16

  • Common risk factors for gonorrhoea are previous infection with N. gonorrhoeae, known contact of gonorrhoea, presence of purulent urethral discharge, men who have sex with men and black ethnicity.

  • Instrumentation and indwelling catheters are common risk factors for acute epididymitis. Urethritis or prostatitis may also co-exist.

  • Structural or functional abnormalities of the urinary tract are common in the group infected with Gram-negative enteric organisms. Adults usually have bladder outlet obstruction or urethral stricture; children may have an ectopic ureter, posterior urethral valves or vesicoureteral reflux.

  • Anal intercourse is also a risk factor for infection with enteric pathogens.

  • Reflux of infected urine from the prostatic urethra to the epididymis via the ejaculatory ducts and vas deferens may be induced by Valsalva manoeuvre or strenuous exertion. Epididymitis is common in men performing strenuous exertion when there is no opportunity to void, resulting in a full bladder.

Epididymo-orchitis symptoms

See also the separate Genitourinary History and Examination (Male) article.

  • It usually presents with unilateral scrotal pain and swelling of relatively acute onset.

  • Acute epididymitis is usually unilateral but is bilateral in 5-10% of the patients.

  • In sexually transmitted epididymo-orchitis there may be symptoms of urethritis or a urethral discharge.

  • There may be a history of symptoms suggesting a urinary tract infection or a history of bacteriuria.

  • Mumps usually presents with headache, fever and unilateral or bilateral parotid swelling but may present with epididymitis. Scrotal involvement can occur without systemic symptoms.

  • Symptoms suggestive of tuberculous infection include subacute/chronic onset of painless or painful scrotal swelling, associated with systemic symptoms of TB, a scrotal sinus or thickened scrotal skin.


  • Tenderness to palpation on the affected side.

  • Palpable swelling of the epididymis, starting with the tail at the lower pole of the testis and spreading towards the head at the upper pole of the testis with or without involvement of the testicle.

  • There may also be urethral discharge, secondary hydrocele, erythema and/or oedema of the scrotum on the affected side and pyrexia.

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Differential diagnosis for epididymo-orchitis

Testicular torsion1

  • Testicular torsion is the most important differential diagnosis. It is a surgical emergency, should be considered in all patients and should be excluded first (testicular salvage is essential within six hours and becomes decreasingly likely with time).

  • Differentiation between epididymo-orchitis and testicular torsion on clinical examination may be difficult and if any doubt exists then urgent surgical exploration is advocated.

  • Torsion is more common in men who are younger than 20 years but it can occur at any age.

  • A painful swollen testicle in an adolescent boy or a young man should be managed as torsion until proven otherwise.

  • Torsion is more likely if the onset of pain is acute (typically around four hours at presentation) and the pain is severe.

Careful evaluation for the possible causes of acute scrotal pain and swelling is essential.17

  • Testicular torsion with ischaemia or infarction.

  • Trauma.

  • Abscess formation.

  • Testicular or epididymal tumour.

  • Hydrocele.


A sexually transmitted cause should always be excluded. The following should be performed:

  • Gram-stained urethral smear (even if urethral symptoms are absent), examined microscopically for the diagnosis of urethritis, (5 or more polymorphonuclear leukocytes per high power field x 1,000) and presumptive diagnosis of gonorrhoea (Gram-negative intracellular diplococci), or Gram-stained preparation from a centrifuged sample of first passed urine (FPU) for microscopy is an alternative method of diagnosing urethritis (10 or more polymorphonuclear leukocytes per high power field x 1,000).

  • Urethral swab for N. gonorrhoeae culture and/or FPU or urethral swab for nucleic acid amplification test (NAAT) for N. gonorrhoeae.

  • FPU or urethral swab for C. trachomatis NAAT.

  • Microscopy and culture of midstream specimen of urine (MSU) for bacteria. Urinalysis including nitrite and/or a leukocyte esterase test is helpful but is not diagnostic.

  • Consider HIV testing if there are any risk factors or clinical suspicion.

  • If it can be arranged without delay, colour Doppler ultrasound to assess arterial blood flow may be useful to help differentiate between epididymo-orchitis and torsion of the spermatic cord (but the sensitivity for detecting torsion may not be 100% and this should not delay surgical exploration of the scrotum).

Further investigations

Other investigations which could be considered include:

  • All patients with sexually transmitted epididymo-orchitis should be screened for other STIs.

  • Anatomical abnormalities of the urinary tract are common in the group infected with Gram-negative enteric organisms and further investigation of the urinary tract should be considered in all such patients, especially in those older than 50 years.

  • When investigating for tuberculous infection, three early morning urine samples should be obtained but these are not always positive for acid-alcohol fast bacilli (AAFB) in the setting of tuberculous epididymitis. Other investigations recommended include intravenous urography, renal tract ultrasound scan and biopsy of the site as well as CXR to exclude or confirm co-existing respiratory involvement.

  • When considering mumps as a possible diagnosis, mumps IgM/IgG serology should be checked.

  • There is no role for epididymal aspiration/fine-needle aspiration cytology in routine clinical practice. It may be useful in recurrent infection which fails to respond to therapy and if epididymo-orchitis is found at operation and in the case of suspected tuberculous epididymitis.

Epididymo-orchitis treatment and management2

  • If there is any possibility of torsion, arrange urgent urology opinion.

  • If there is possible STI - eg, younger age, multiple partners or new partner:

    • Refer urgently to a genitourinary clinic for full STI screen, treatment and contact tracing.

    • Advise to avoid unprotected sex until treatment and follow-up, including tracing and treating sexual contacts, have been completed.

General advice

  • Appropriate rest, analgesia and scrotal support are recommended.

  • Non-steroidal anti-inflammatory drugs may be helpful.

  • Patients should be advised to abstain from sexual intercourse until they and their partner(s) have completed treatment and follow-up in those with confirmed or suspected sexually transmitted epididymo-orchitis.

Drugs for epididymo-orchitis1 2 17

Empirical therapy should be given to all patients with epididymo-orchitis immediately after diagnosis and before culture/NAAT results are available.16

If urgent referral to a local specialist sexual health clinic is not possible, start empirical antibiotic treatment in primary care. Advise the person to abstain from sexual contact until they and any partner(s) have completed treatment and follow-up if there is a confirmed or suspected STI. Ideally follow-up and contact tracing should be arranged by a local specialist sexual health clinic.

The antibiotic regimen chosen should be determined in the light of the immediate tests (urethral or FPU smear, urinalysis) as well as age, sexual history including insertive anal intercourse, any recent instrumentation or catheterisation and any known urinary tract abnormalities. Antibiotics may need to be varied according to local knowledge of antibiotic sensitivities and changed once the results of cultures and sensitivities are known.

  • If epididymo-orchitis is most likely due to any STI:

    • Treat empirically with ceftriaxone 1 g intramuscular (IM) injection as a single dose, depending on local prescribing protocols, plus oral doxycycline 100 mg twice daily for 10-14 days. If a cephalosporin and/or tetracycline antibiotic is contra-indicated, treat with oral ofloxacin 200 mg twice daily for 14 days.

  • If epididymo-orchitis is most likely due to chlamydia or other non-gonococcal organisms (if no risk factors for gonorrhoea):

    • Treat empirically with oral doxycycline 100 mg twice daily for 10-14 days, or oral ofloxacin 200 mg twice daily for 14 days. If a quinolone antibiotic is contra-indicated, treat with oral co-amoxiclav 500/125 mg three times a day for 10 days.

  • If epididymitis is most likely due to an STI and/or enteric organism (eg, men who have insertive anal sex):

    • Consider treating empirically with ceftriaxone 1 g IM, depending on local prescribing protocols, plus oral ofloxacin 200 mg twice daily for 14 days. If a quinolone antibiotic is contra-indicated, treat with oral co-amoxiclav 500/125 mg three times a day for 10 days.

If treating with fluoroquinolone antibiotics in primary care: advise that these can very rarely cause long-lasting, potentially irreversible adverse effects affecting the tendons, muscles, joints, and/or central nervous system. Advise stopping fluoroquinolone antibiotic treatment immediately and seeking immediate medical advice if the patient develops serious tendon, muscle, or joint pain or inflammation, peripheral neuropathy or any other serious CNS adverse effect.

Sexual partners

Partner notification and treatment are recommended for all patients with epididymo-orchitis secondary to gonorrhoea, chlamydia and non-gonococcal urethritis (NGU) or of indeterminate aetiology and subsequent MSU negative.


  • If there is no improvement in the patient's condition after three days, the diagnosis should be reassessed and therapy re-evaluated.

  • Further follow-up is recommended at two weeks to assess compliance with treatment, partner notification and improvement of symptoms.

  • The swelling and tenderness can persist after antimicrobial therapy is completed but should be significantly improved. Where there is little improvement, further investigations such as an ultrasound scan or surgical assessment should be considered.


  • Scrotal exploration if a torsion or tumour cannot be ruled out and for the complications of acute epididymitis and orchitis (eg, abscess, testicular infarction).11

Epididymo-orchitis complications17

Complications are more often seen in patients with uropathogen-related epididymo-orchitis than STI-associated epididymo-orchitis.

  • Sepsis.

  • Abscess formation and ischaemia/infarction of the testicle.

  • Reactive hydrocele.

  • Testicular atrophy and subfertility - eg, mumps orchitis.

  • Chronic scrotal pain.

Mumps epididymo-orchitis can lead to testicular atrophy, sub-fertility and infertility.14

Further reading and references

  • Walker NA, Challacombe B; Managing epididymo-orchitis in general practice. Practitioner. 2013 Apr;257(1760):21-5, 2-3.
  • D'Andrea A, Coppolino F, Cesarano E, et al; US in the assessment of acute scrotum. Crit Ultrasound J. 2013 Jul 15;5 Suppl 1:S8. doi: 10.1186/2036-7902-5-S1-S8. Epub 2013 Jul 15.
  • Zhao S, Zhu W, Xue S, et al; Testicular defense systems: immune privilege and innate immunity. Cell Mol Immunol. 2014 Sep;11(5):428-37. doi: 10.1038/cmi.2014.38. Epub 2014 Jun 23.
  1. United Kingdom BASHH national guideline for the management of epididymo-orchitis; British Association for Sexual Health and HIV (2019)
  2. Sexually Transmitted Infections in Primary Care; Royal College of General Practitioners and British Association for Sexual Health and HIV (Apr 2013)
  3. Baron EJ, Miller JM, Weinstein MP, et al; A guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2013 recommendations by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM)(a). Clin Infect Dis. 2013 Aug;57(4):e22-e121. doi: 10.1093/cid/cit278. Epub 2013 Jul 10.
  4. British National Formulary (BNF); NICE Evidence Services (UK access only)
  5. Trojian TH, Lishnak TS, Heiman D; Epididymitis and orchitis: an overview. Am Fam Physician. 2009 Apr 1;79(7):583-7.
  6. Varicella; Centers for Disease Control and Prevention
  7. Doyle J et al; Mumps presenting as epididymo-orchitis among young travellers: under-recognition, missed diagnoses and transmission risks. Med J Aust 2011; 194 (6): 317-318.
  8. Richens J; Main presentations of sexually transmitted infections in men. BMJ. 2004 May 22;328(7450):1251-3.
  9. Varma R, Baithun S, Alexander S, et al; Acute syphilitic interstitial orchitis mimicking testicular malignancy in an HIV-1 infected man diagnosed by Treponema pallidum polymerase chain reaction. Int J STD AIDS. 2009 Jan;20(1):65-6. doi: 10.1258/ijsa.2008.008253.
  10. Salvi S, Chopra A; Leprosy in a rheumatology setting: a challenging mimic to expose. Clin Rheumatol. 2013 Oct;32(10):1557-63. doi: 10.1007/s10067-013-2276-5. Epub 2013 May 7.
  11. Urological infections; European Association of Urology (2022)
  12. Gkentzis A, Lee L; The aetiology and current management of prepubertal epididymitis. Ann R Coll Surg Engl. 2014 Apr;96(3):181-3. doi: 10.1308/003588414X13814021679311.
  13. Philip J, Selvan D, Desmond AD; Mumps orchitis in the non-immune postpubertal male: a resurgent threat to male fertility? BJU Int. 2006 Jan;97(1):138-41.
  14. Davis NF, McGuire BB, Mahon JA, et al; The increasing incidence of mumps orchitis: a comprehensive review. BJU Int. 2010 Apr;105(8):1060-5. doi: 10.1111/j.1464-410X.2009.09148.x. Epub 2010 Jan 11.
  15. Bedi N, Rahimi MNC, Menzies S, et al; Atypical testicular pain. BMJ Case Rep. 2019 Feb 19;12(2). pii: 12/2/e226697. doi: 10.1136/bcr-2018-226697.
  16. Banyra O, Nikitin O, Ventskivska I; Acute epididymo-orchitis: relevance of local classification and partner's follow-up. Cent European J Urol. 2019;72(3):324-329. doi: 10.5173/ceju.2019.1973. Epub 2019 Aug 22.
  17. Scrotal pain and swelling; NICE CKS; January 2022 (UK access only)

Article history

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