What are the implications and treatments for a green rectal discharge?

Green Rectal Discharge: Evaluation and Management

Green rectal discharge most commonly indicates infectious proctitis requiring immediate microbiological evaluation and empiric antimicrobial therapy, though inflammatory bowel disease and anorectal abscess must be excluded through focused clinical assessment and targeted investigations.

Immediate Clinical Assessment

The color and character of rectal discharge provides critical diagnostic clues:

• Green discharge specifically suggests purulent infection, most commonly from sexually transmitted organisms including Neisseria gonorrhoeae, Chlamydia trachomatis, or mixed anaerobic bacteria from an anorectal abscess 1, 2
• Obtain focused sexual history including receptive anal intercourse, number of partners, and HIV status, as these are major risk factors for infectious proctitis 3, 2
• Perform digital rectal examination to assess for fluctuance suggesting abscess, though imaging should precede examination if sharp foreign body is suspected 1
• Document associated symptoms: fever (suggests abscess or systemic infection), tenesmus, urgency, and rectal bleeding 3, 2

Diagnostic Workup

Obtain rectal swabs for culture and PCR before initiating antibiotics:

• Test for N. gonorrhoeae, C. trachomatis, Treponema pallidum, herpes simplex virus, and Mycoplasma genitalium 3, 2
• Request complete blood count and inflammatory markers (C-reactive protein, procalcitonin) if systemic infection or abscess is suspected 1
• Perform proctoscopy with biopsy to distinguish infectious proctitis from inflammatory bowel disease, as endoscopic and histological features overlap significantly 2

Imaging is essential when abscess is suspected:

• Plain X-ray of abdomen/pelvis can identify free air suggesting perforation 1
• CT or MRI defines abscess anatomy and extent, guiding drainage approach 1
• Ultrasound may identify perianal abscesses but is operator-dependent 1

Treatment Algorithm

If Infectious Proctitis is Suspected (No Abscess):

Initiate empiric therapy immediately after obtaining cultures:

• Ceftriaxone 250-500 mg IM single dose PLUS doxycycline 100 mg orally twice daily for 7 days covers gonorrhea and chlamydia 3
• Add metronidazole if anaerobic infection suspected based on foul odor or mixed flora 1
• Adjust antibiotics based on culture results and clinical response 3

If Anorectal Abscess is Identified:

Surgical drainage is mandatory and should not be delayed:

• Incision and drainage is the definitive treatment; timing depends on severity of sepsis 1
• Emergent drainage required if patient has sepsis, severe sepsis, septic shock, immunosuppression, diabetes, or diffuse cellulitis 1
• Otherwise, perform drainage within 24 hours 1
• Administer empiric broad-spectrum antibiotics covering aerobic and anaerobic organisms due to risk of bacterial translocation 1

If Inflammatory Bowel Disease Cannot Be Excluded:

• Defer IBD-specific therapy until infection is ruled out, as immunosuppression during active infection increases morbidity 2
• Histopathology showing fibromuscular obliteration of lamina propria suggests solitary rectal ulcer syndrome rather than IBD 4
• Repeat endoscopy after treating infection if diagnosis remains unclear 2

Critical Pitfalls to Avoid

• Do not assume hemorrhoids or anal fissure when green discharge is present—this color indicates infection requiring antimicrobial therapy 5
• Do not delay abscess drainage for further testing; inadequate or delayed drainage leads to recurrence rates up to 44% 1
• Do not start immunosuppressive therapy for presumed IBD without excluding infection first, as sexually transmitted proctitis mimics IBD endoscopically 3, 2
• Do not forget HIV and syphilis testing in all patients with infectious proctitis, as these alter management and prognosis 2

Follow-Up Requirements

• Repeat examination at 2 months to confirm resolution and assess for complications 3
• Test for cure is recommended for gonorrhea and chlamydia 3-4 weeks after treatment completion 3
• Abscess patients require monitoring for fistula formation, which occurs in 25-50% of cases, especially with gut-derived organisms 5
• Consider colonoscopy if symptoms persist despite appropriate antimicrobial therapy to evaluate for IBD or other pathology 2