Scrotal Abscess

Scrotal abscess is a localised collection of pus within the scrotal wall or the scrotal contents. It ranges from a simple cutaneous abscess to a deep collection with testicular involvement, and it can be the early focus of necrotising infection (Fournier gangrene).

Anatomical types

• Scrotal wall (cutaneous or subcutaneous) abscess: the commonest, arising from folliculitis, an infected sebaceous cyst, hidradenitis suppurativa, or trauma.
• Intrascrotal abscess: epididymal abscess or testicular abscess (complication of epididymo-orchitis, mumps orchitis, trauma, or infarcted tumour).
• Pyocele: pus within the tunica vaginalis, from rupture of an abscess or infected hydrocele.
• Extension from adjacent sites: perianal or perineal abscess, ischiorectal abscess, urethral stricture with periurethral extravasation, Crohn fistula, infected hernia sac, or retroperitoneal sepsis.

Risk factors

• Diabetes mellitus (the most important, in a large proportion), obesity, poor hygiene, immunosuppression (HIV, steroids, chemotherapy), alcohol misuse, chronic kidney disease, and injecting drug use.
• Indwelling catheter, urethral stricture, recent instrumentation or surgery (vasectomy, hernia repair, circumcision), perineal trauma, and chronic skin disease.
• Hidradenitis suppurativa and recurrent folliculitis.

Microbiology

• Staphylococcus aureus (including community-acquired MRSA) in most superficial lesions.
• Streptococci, E. coli, Proteus, Klebsiella, Pseudomonas, Enterococcus, and anaerobes (Bacteroides) in deeper or perineal disease.
• Polymicrobial infection is typical in diabetic and necrotising cases.
• Specific causes: tuberculosis (cold abscess with sinus), brucellosis, Burkholderia pseudomallei (melioidosis, endemic Southeast Asia and northern Australia), schistosomiasis, and fungal infection in the immunosuppressed.
• Complications: Fournier gangrene, sepsis and septic shock, testicular loss, chronic sinus or fistula, scrotal skin loss, epididymal scarring with infertility, and recurrence.

Superficial abscess

• Painful, tender, red, warm swelling of the scrotal skin, fluctuant when mature, with a central punctum or pointing area. Fever and malaise in a proportion.
• Regional inguinal lymphadenopathy, surrounding cellulitis, and discharge if it has ruptured.

Intrascrotal abscess

• Testicular or epididymal pain and swelling, fever and rigors, a tense reactive hydrocele, and marked scrotal oedema. The testis may be enlarged and tender with loss of normal landmarks. Fluctuance is not always evident.
• Often follows an episode of epididymo-orchitis that has failed to settle in 48 to 72 hours.

Features suggesting underlying causes

• Recurrent lesions in the groin, axillae and perineum (hidradenitis).
• Urinary retention, poor stream or stricture history (periurethral extravasation).
• Perianal pain, discharge or fistula (anorectal origin).
• Chronic sinus with weight loss and night sweats (tuberculosis).

Red flags for necrotising soft tissue infection (Fournier gangrene)

• Pain out of proportion to the findings, rapidly spreading erythema, dusky or black skin, bullae, crepitus, foul-smelling discharge, and anaesthesia of the skin.
• Fever with tachycardia, hypotension, and altered mental state.
• Diabetes, immunosuppression, and perineal or urethral source.
• Differential diagnosis: epididymo-orchitis, testicular torsion, strangulated or incarcerated inguinal hernia, infected hydrocele, haematoma, infected sebaceous cyst, testicular tumour with necrosis, scrotal cellulitis, scrotal calcinosis, and cutaneous Crohn disease.

Clinical diagnosis for superficial collections. Imaging is required when the extent or depth is uncertain. Do not delay surgery for imaging if necrotising infection is suspected.

Laboratory tests

• CBC, CRP, creatinine, electrolytes, glucose and HbA1c, lactate, and coagulation.
• Blood cultures before antibiotics in febrile or septic patients.
• Pus culture and sensitivity, including anaerobic cultures, with Gram stain. AFB smear, culture and PCR when tuberculosis is possible, and fungal culture when indicated.
• Urinalysis, urine culture, and urethral NAAT.
• HIV test, and screen for other immunosuppression.
• The LRINEC score (CRP, white count, haemoglobin, sodium, creatinine, glucose) of 6 or more raises suspicion of necrotising infection, but a low score does not exclude it.

Scrotal colour Doppler ultrasound

• Heterogeneous fluid collection with septations and debris, thickened scrotal wall, gas echoes (dirty shadowing), reactive hydrocele, enlarged epididymis or testis, and areas of absent flow indicating infarction.
• Used to assess testicular viability and to exclude torsion and tumour.

CT or MRI of the pelvis and perineum

• Defines extension to the perineum, ischiorectal fossa, inguinal canal, retroperitoneum and thigh. CT shows gas in tissue planes, fascial thickening, and a perianal or urethral source.
• MRI helps in hidradenitis, fistula and complex perineal disease.

Further evaluation

• Retrograde urethrogram or cystoscopy for suspected urethral stricture or extravasation.
• Colonoscopy or anorectal examination under anaesthesia for perianal origin, and flexible sigmoidoscopy in Crohn disease.
• Biopsy of chronic sinuses to exclude malignancy and granulomatous disease.

Drainage is the definitive treatment. Antibiotics alone fail in established collections.

Superficial abscess

• Incision and drainage under local anaesthesia (lidocaine 1% with adrenaline, infiltrating around not into the cavity), or under sedation for large lesions.
• Make a generous incision over the most fluctuant area along the skin lines, break down loculations, send pus for culture, irrigate with saline, and leave the cavity open with loose packing or a wick. Change packing at 24 to 48 hours, then daily with warm saline soaks or sitz baths until granulation.
• Analgesia with paracetamol 1 g every 6 hours and ibuprofen 400 mg every 8 hours. Tetanus prophylaxis if due.
• Antibiotics are added for systemic signs, extensive cellulitis, diabetes, immunosuppression, or MRSA risk, for 5 to 7 days after drainage:
  • Cefalexin 500 mg four times daily, or flucloxacillin 500 mg to 1 g four times daily.
  • Clindamycin 300 to 450 mg three to four times daily, or trimethoprim-sulfamethoxazole 160/800 mg twice daily, or doxycycline 100 mg twice daily when MRSA is suspected.
  • Add Gram-negative and anaerobic cover (amoxicillin-clavulanate 875/125 mg twice daily) for perineal or urinary sources.

Intrascrotal abscess, pyocele and testicular abscess

• Admit. Start IV antibiotics: ceftriaxone 2 g daily with metronidazole 500 mg every 8 hours, or piperacillin-tazobactam 4.5 g every 6 hours. Add vancomycin 15 to 20 mg/kg every 8 to 12 hours when MRSA is likely.
• Ultrasound-guided aspiration for small collections, and surgical exploration with drainage and debridement for larger or loculated abscess. Epididymectomy or orchiectomy for non-viable testis, uncontrolled sepsis, or failure of drainage.
• Duration 2 to 4 weeks, guided by response and imaging. Convert to oral therapy when afebrile and improving.

Necrotising infection (Fournier gangrene), a surgical emergency

• Immediate resuscitation: IV crystalloid, vasopressors for shock (norepinephrine 0.05 to 0.5 micrograms/kg/min), oxygen, and correction of glucose, electrolytes and coagulopathy.
• Broad-spectrum antibiotics without delay:
  • Piperacillin-tazobactam 4.5 g IV every 6 hours (or meropenem 1 g IV every 8 hours).
  • Plus vancomycin 15 to 20 mg/kg IV every 8 to 12 hours (or linezolid 600 mg IV every 12 hours).
  • Plus clindamycin 900 mg IV every 8 hours to suppress toxin production.
• Urgent radical surgical debridement of all necrotic tissue to bleeding margins, with repeat debridement every 24 to 48 hours until clean. The testes are often spared because of their separate blood supply, and are protected in thigh pouches or covered with moist dressings.
• Diverting colostomy for faecal contamination or sphincter involvement, and suprapubic catheter for urethral injury.
• ICU care, nutritional support, and tight glycaemic control with insulin infusion (target 140 to 180 mg/dL).
• Hyperbaric oxygen is an optional adjunct with unproven benefit.
• Wound care with negative pressure therapy, then reconstruction with split-skin grafts, local flaps, or thigh pouches.
• Mortality is 15 to 40%, higher with delay, diabetes, sepsis and extensive disease.

Specific causes

• Tuberculosis: standard anti-tuberculosis therapy for 6 months, with drainage and excision of sinuses.
• Brucellosis: doxycycline plus rifampicin for 6 weeks.
• Melioidosis: ceftazidime 2 g IV every 6 to 8 hours or meropenem 1 g IV every 8 hours for at least 10 to 14 days, followed by trimethoprim-sulfamethoxazole for 3 to 6 months.

Source control and prevention of recurrence

• Relieve urinary obstruction, treat urethral stricture, and drain perianal collections.
• Excise sebaceous cysts and chronic sinuses once the infection has settled.
• Recurrent S. aureus infection: decolonise with mupirocin 2% to the nostrils twice daily for 5 days, chlorhexidine 4% body wash for 5 to 14 days, and treat household contacts where appropriate.
• Optimise diabetes control, weight, hygiene and skin care.

Follow-up

• Review at 48 hours for wound inspection, packing, and culture results. Review again at 1 and 2 weeks.
• Repeat ultrasound if fever persists, to rule out undrained collection or testicular infarction.
• Semen analysis at 3 months after testicular or bilateral disease. Counsel about recurrence risk and when to return urgently.