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uro.epididymitis-orchitis.v1PRODUCTION
uro.epididymitis-orchitis.v1

Acute epididymitis ± orchitis (STI / enteric / viral / TB / drug / torsion-pivot DDx)

urologyacutesubacuteadultpediatricgeriatric
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Care setting:

Encounter flow

12/12 authored

Canonical 12-phase frame with authored status for this dossier.

Current phase

Frame

Detailed

Scrotal pain with gradual onset + epididymal tenderness — gauge STI vs enteric vs viral vs granulomatous vs drug vs torsion pivot (EAU 2017; CDC STI 2021)

Inputs
2
Actions
0
Advance rule
Set
Advance when

engine scope confirmed (not torsion)

Patient inputs (20)

STI-acquired marker (CDC STI 2021)

Active sexual history with new / multiple partners → STI workup (CDC STI 2021)

Enteric pathogens (E. coli) cover in addition to STI (CDC STI 2021; EAU 2017)

Catheter, cystoscopy, prostate biopsy → enteric/healthcare pathogen (EAU 2017)

Sudden (<minutes) → torsion pivot; gradual (hours-days) → epididymitis (Barbosa 2013 TWIST; EAU 2017)

Preserved in epididymitis; absent in torsion (Barbosa 2013)

Drives empiric — <35 STI-acquired (ceftriaxone + doxycycline); ≥35 enteric (FQ or TMP-SMX) (CDC STI 2021; EAU 2017)

Pyuria common in bacterial epididymitis; absence supports torsion or non-bacterial (EAU 2017)

Identify enteric or healthcare pathogen for narrowing (EAU 2017)

NAAT for chlamydia, gonorrhea, trichomonas, Mycoplasma genitalium (CDC STI 2021)

Leukocytosis → severity / abscess concern (EAU 2017)

Hyperemia + enlarged epididymis = epididymitis; absent intratesticular flow = torsion; abscess as discrete fluid collection (Friedman 2017)

High fever → abscess / severe / route inpatient (EAU 2017)

Hypotension + fever → sepsis (route ICU) (SCC 2026)

BPH or obstructive uropathy increases retrograde infection risk (EAU 2017)

Mumps orchitis in post-pubertal unvaccinated males (Davis 2010)

Tubercular epididymo-orchitis — chronic, beaded vas, painless or low-grade (EAU 2017)

Brucella orchitis in endemic regions or unpasteurized dairy (EAU 2017)

Amiodarone-induced orchitis (uncommon but documented)

CRP elevation supports bacterial; very high → abscess (EAU 2017)

* = hard-required. Engine cannot meaningfully run until these are filled.

Severity triggers (10)

10 need judgement
  • informationallife_threateningtesticular_torsion_pivot_DDx
    Sudden severe pain + N/V + absent cremasteric + high-riding testis OR TWIST 5–7 OR absent intratesticular flow on POCUS — STAT OR for testicular torsion (route off engine to uro.testicular-torsion.v1) (Barbosa 2013; AUA 2017; Friedman 2017)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalsevereabscess_complication
    Discrete fluctuant scrotal mass OR POCUS confirms discrete fluid collection OR failure of 48–72 h empiric — epididymo-orchitic abscess (EAU 2017)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatesti_acquired_younger_men
    Younger man (<35) + sexually active + urethral discharge OR positive NAAT — chlamydia / gonorrhea / M. genitalium → CDC dual therapy (CDC STI 2021 PMID 33417591)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderateenteric_pathogen_older_men_or_anal
    ≥35 y OR BPH OR recent urologic instrumentation OR insertive anal intercourse — enteric E. coli → FQ or TMP-SMX (EAU 2017)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatetubercular_chronic
    Chronic painless or low-grade scrotal swelling with beaded vas OR known TB exposure / endemic — tubercular epididymo-orchitis (EAU 2017)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatemumps_orchitis_post_pubertal
    Post-pubertal unvaccinated male with parotid swelling + scrotal pain 4–8 d after parotitis — mumps orchitis (Davis 2010 PMID 22421094)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmoderatebrucella_orchitis_endemic
    Endemic region OR unpasteurized dairy / livestock exposure + scrotal pain — Brucella orchitis (EAU 2017)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmildgranulomatous_idiopathic
    Granulomatous histology on biopsy without infection identified — idiopathic granulomatous orchitis (rare; EAU 2017)
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmildamiodarone_induced
    Patient on amiodarone + painful scrotal swelling + negative microbiology — drug-induced orchitis
    Trigger could not be auto-evaluated — needs clinician judgement.
  • informationalmildchronic_epididymalgia_post_vasectomy
    Chronic scrotal pain >3 mo post-vasectomy OR persistent after epididymitis — chronic epididymalgia / post-vasectomy pain syndrome
    Trigger could not be auto-evaluated — needs clinician judgement.

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Recommended regimen

Acute epididymitis ± orchitis — STI dual therapy (CDC 2021) + enteric FQ/TMP-SMX (EAU 2017) + mumps supportive + TB/brucella ID-directed + abscess drainage + supportive
axis: epididymitis_orchitis_empiric_and_targetedstep 1 - STI-suspected (<35 y, sexually active) — CDC dual therapy 2021
Selected step "STI-suspected (<35 y, sexually active) — CDC dual therapy 2021" — Younger man (<35) with new sexual partner OR urethral discharge OR positive NAAT pending
  • ceftriaxone
    first line
    cephalosporin_3rd_gen
    500 mg IM × 1 • IM • single dose
    triggers: sti_suspected_chlamydia_or_gonorrhea
    CDC STI 2021 — increased dose to 500 mg IM (was 250 mg) for gonorrhea coverage; single dose; pair with doxycycline (PMID 33417591)
    rxcui 2193
  • doxycycline
    first line
    tetracycline
    100 mg PO BID × 10 days • PO • BID × 10 days
    triggers: sti_suspected_chlamydia_or_M_genitalium_consideration
    CDC STI 2021 — chlamydia + M. genitalium coverage; 10-day course for epididymitis (longer than urethritis 7-day)
    rxcui 3640
  • metronidazole
    add on
    nitroimidazole
    500 mg PO BID × 10 days • PO • BID × 10 days
    triggers: insertive_anal_intercourse_anaerobe_coverage, trichomonas_positive
    Add for insertive anal sex (enteric + anaerobe overlap) or trichomonas (CDC STI 2021)
    rxcui 6922

outpatient playbook — drug actions (6)

  1. 1. ceftriaxone (STI)
    500 mg IM × 1 • IM • single dose
    trigger: STI-suspected, <35 y
    CDC STI 2021 — gonorrhea coverage (PMID 33417591)
  2. 2. doxycycline (STI)
    100 mg PO BID × 10 d • PO • BID
    trigger: STI-suspected, pair with ceftriaxone
    CDC STI 2021 — chlamydia + M. genitalium coverage
  3. 3. metronidazole (anal sex)
    500 mg PO BID × 10 d • PO • BID
    trigger: Insertive anal intercourse OR trichomonas positive
    Anaerobe + trichomonas coverage (CDC STI 2021)
  4. 4. levofloxacin (enteric)
    500 mg PO daily × 10 d • PO • once daily
    trigger: ≥35 y or BPH or instrumentation
    EAU 2017 — excellent prostate / epididymis penetration; FDA Black Box counsel
  5. 5. TMP-SMX (alternative)
    160/800 mg PO BID × 10 d • PO • BID
    trigger: FQ contraindicated; culture-susceptible
    EAU 2017 alternative; INR + methotrexate interactions
  6. 6. ibuprofen + acetaminophen (multimodal)
    Ibuprofen 400–600 mg + acetaminophen 650–1000 mg q6h • PO • q6h
    trigger: Pain
    Opioid-sparing multimodal

Auto-drafted A&P note

outpatient

Subjective

- Possible entry pathways: Gradual unilateral scrotal pain + swelling over hours to days (EAU urological infections 2017); Posterior testicular tenderness localised to epididymis (Prehn sign — relief with elevation suggestive, not diagnostic) (EAU 2017); Dysuria / urethral discharge + scrotal pain in young man — STI-acquired (CDC STI 2021).

Objective

- No vitals, labs, or imaging entered for this encounter.

Assessment

**Acute epididymitis ± orchitis (STI / enteric / viral / TB / drug / torsion-pivot DDx)** (uro.epididymitis-orchitis.v1).
Phenotype framing: Epididymitis vs orchitis vs testicular torsion vs torsion of appendix testis vs Fournier (sepsis + crepitus) vs incarcerated hernia vs scrotal trauma vs HSP vs idiopathic scrotal edema vs malignancy (EAU 2017; AUA 2017)
Scope: Scrotal pain with gradual onset + epididymal tenderness — gauge STI vs enteric vs viral vs granulomatous vs drug vs torsion pivot (EAU 2017; CDC STI 2021)

No severity triggers fired against current inputs.

Plan

Regimen axis: **Acute epididymitis ± orchitis — STI dual therapy (CDC 2021) + enteric FQ/TMP-SMX (EAU 2017) + mumps supportive + TB/brucella ID-directed + abscess drainage + supportive** — step "STI-suspected (<35 y, sexually active) — CDC dual therapy 2021".
1. ceftriaxone 500 mg IM × 1 IM single dose (cephalosporin_3rd_gen, first line) — CDC STI 2021 — increased dose to 500 mg IM (was 250 mg) for gonorrhea coverage; single dose; pair with doxycycline (PMID 33417591)
2. doxycycline 100 mg PO BID × 10 days PO BID × 10 days (tetracycline, first line) — CDC STI 2021 — chlamydia + M. genitalium coverage; 10-day course for epididymitis (longer than urethritis 7-day)
3. metronidazole 500 mg PO BID × 10 days PO BID × 10 days (nitroimidazole, add on) — Add for insertive anal sex (enteric + anaerobe overlap) or trichomonas (CDC STI 2021)

Setting playbook (outpatient) — Stable, PO-tolerant, no abscess / sepsis / torsion → CDC dual therapy if STI-suspected (ceftriaxone 500 mg IM + doxycycline 100 mg PO BID × 10 d) OR levofloxacin 500 mg PO daily × 10 d if enteric. Always culture; 48–72 h follow-up; partner notification (CDC STI 2021; EAU 2017)
4. ceftriaxone (STI) 500 mg IM × 1 IM single dose — STI-suspected, <35 y (CDC STI 2021 — gonorrhea coverage (PMID 33417591))
5. doxycycline (STI) 100 mg PO BID × 10 d PO BID — STI-suspected, pair with ceftriaxone (CDC STI 2021 — chlamydia + M. genitalium coverage)
6. metronidazole (anal sex) 500 mg PO BID × 10 d PO BID — Insertive anal intercourse OR trichomonas positive (Anaerobe + trichomonas coverage (CDC STI 2021))
7. levofloxacin (enteric) 500 mg PO daily × 10 d PO once daily — ≥35 y or BPH or instrumentation (EAU 2017 — excellent prostate / epididymis penetration; FDA Black Box counsel)
8. TMP-SMX (alternative) 160/800 mg PO BID × 10 d PO BID — FQ contraindicated; culture-susceptible (EAU 2017 alternative; INR + methotrexate interactions)
9. ibuprofen + acetaminophen (multimodal) Ibuprofen 400–600 mg + acetaminophen 650–1000 mg q6h PO q6h — Pain (Opioid-sparing multimodal)

Non-pharmacologic actions:
- Patient education — symptom trajectory + return precautions (worsening, fever, new mass, no improvement at 48–72 h)
- 48–72 h follow-up call; culture + NAAT results at 24–48 h → narrow / broaden per susceptibility
- Partner notification + EPT per state law (STI cases) (CDC STI 2021)
- Abstinence from intercourse for 7 d post-treatment (CDC STI 2021)
- STI re-test at 3 months for reinfection surveillance (CDC STI 2021)
- Scrotal elevation + ice pack + supportive underwear
- Urology referral if non-resolving > 2 wk OR chronic epididymalgia OR suspected malignancy

AVOID / contraindication checks:
- Fluoroquinolones_FDA_black_box_tendinopathy_aortic_CNS_dysglycemia (FDA 2016)
- Fluoroquinolones_avoid_throughout_pregnancy_cartilage (FDA / IDSA)
- Doxycycline_avoid_in_pregnancy_and_children_lt_8y_teeth (FDA)
- Doxycycline_photosensitivity_GI_upset_with_food_avoid_dairy_and_antacids_2h_apart (FDA)
- Ceftriaxone_avoid_in_neonates_kernicterus_calcium_compatibility (FDA)
- Metronidazole_disulfiram_reaction_with_alcohol (FDA)
- TMP_SMX_avoid_near_term_pregnancy_kernicterus (USPSTF)
- TMP_SMX_interaction_with_warfarin_INR_rise (IDSA 2010)
- NSAIDs_avoid_in_renal_impairment_or_active_GI_bleed_or_anticoagulation (FDA)
- Do_NOT_treat_as_epididymitis_if_TWIST_5_to_7_or_absent_intratesticular_flow (AUA 2017; Barbosa 2013)
- Mumps_orchitis_no_antiviral_benefit_supportive_only (Davis 2010)
- Amiodarone_orchitis_requires_drug_discontinuation_per_cardiology (FDA)
- Partner_notification_and_abstinence_7d_post_treatment_for_STI (CDC STI 2021)

Monitoring

Regimen monitoring:
- pain and fever resolution by 48 to 72h (EAU 2017)
- urine culture results at 24 to 48h narrow per susceptibility (EAU 2017)
- STI NAAT results partner notification and EPT (CDC STI 2021)
- serial scrotal exam for abscess development (EAU 2017)
- POCUS repeat at 48 to 72h if no improvement (Friedman 2017)
- FQ prolonged course monitor tendinopathy CNS dysglycemia (FDA)
- STI re test at 3 months for reinfection surveillance (CDC STI 2021)
- fertility counsel if bilateral mumps orchitis (Davis 2010)

Setting (outpatient) monitoring:
- Symptom + fever resolution at 48–72 h (EAU 2017)
- Culture + NAAT results at 24–48 h (CDC STI 2021)
- Serial scrotal exam for abscess development (EAU 2017)
- FQ prolonged course → tendinopathy / dysglycemia (FDA)

Follow-up plan: Urology if non-resolving > 2 wk / suspected malignancy / abscess; fertility counsel if bilateral / mumps; chronic epididymalgia management; STI re-test in 3 months (CDC STI 2021; EAU 2017)
- Close-out criterion: follow-up scheduled

Monitoring phase: Symptom + fever resolution at 48–72 h; partner notification + EPT for STI; culture-directed narrowing at 48 h; serial POCUS if abscess concern (CDC STI 2021; EAU 2017)

Disposition

Current setting: outpatient — Stable, PO-tolerant, no abscess / sepsis / torsion → CDC dual therapy if STI-suspected (ceftriaxone 500 mg IM + doxycycline 100 mg PO BID × 10 d) OR levofloxacin 500 mg PO daily × 10 d if enteric. Always culture; 48–72 h follow-up; partner notification (CDC STI 2021; EAU 2017)

Disposition criteria:
- Discharge with oral abx + 48–72 h follow-up + return precautions (CDC STI 2021; EAU 2017)
- Admit if abscess / sepsis / non-PO / failure

Escalation triggers (move to higher acuity):
- Treatment failure at 48–72 h → admit + POCUS for abscess / consider torsion pivot (EAU 2017; AUA 2017)
- Fever ≥38.5°C → admit (abscess / sepsis; EAU 2017)
- Sepsis screen positive → ED (SCC 2026)
- Discrete fluctuant mass → STAT urology (abscess; EAU 2017)
- Suspected torsion (sudden onset, TWIST 5–7, absent flow) → STAT OR (AUA 2017)

Earlier-Return Triggers

Return-precaution thresholds (watch for):
- [LIFE_THREATENING] Sudden severe pain + N/V + absent cremasteric + high-riding testis OR TWIST 5–7 OR absent intratesticular flow on POCUS — STAT OR for testicular torsion (route off engine to uro.testicular-torsion.v1) (Barbosa 2013; AUA 2017; Friedman 2017)
- [SEVERE] Discrete fluctuant scrotal mass OR POCUS confirms discrete fluid collection OR failure of 48–72 h empiric — epididymo-orchitic abscess (EAU 2017)
- [MODERATE] Younger man (<35) + sexually active + urethral discharge OR positive NAAT — chlamydia / gonorrhea / M. genitalium → CDC dual therapy (CDC STI 2021 PMID 33417591)

Citations

- CDC STI Treatment Guidelines 2021 (Workowski MMWR) + acute scrotal pain reviews (Emerg Med Clin North Am; Ann Med Surg systematic review) + epididymo-orchitis ultrasound/UA utility study + adult testicular-torsion review (torsion pivot) [PMID:34292926](https://pubmed.ncbi.nlm.nih.gov/34292926/)
- Cited evidence (PMID 9889740) [PMID:9889740](https://pubmed.ncbi.nlm.nih.gov/9889740/)
- Cited evidence (PMID 32547738) [PMID:32547738](https://pubmed.ncbi.nlm.nih.gov/32547738/)
- Cited evidence (PMID 32214857) [PMID:32214857](https://pubmed.ncbi.nlm.nih.gov/32214857/)
- Cited evidence (PMID 41905882) [PMID:41905882](https://pubmed.ncbi.nlm.nih.gov/41905882/)

Last reconciled with current guidelines: 2026-05-30.
References
  • CDC STI Treatment Guidelines 2021 (Workowski MMWR) + acute scrotal pain reviews (Emerg Med Clin North Am; Ann Med Surg systematic review) + epididymo-orchitis ultrasound/UA utility study + adult testicular-torsion review (torsion pivot) — PMID:34292926
  • Cited evidence (PMID 9889740) — PMID:9889740
  • Cited evidence (PMID 32547738) — PMID:32547738
  • Cited evidence (PMID 32214857) — PMID:32214857
  • Cited evidence (PMID 41905882) — PMID:41905882