🧠 Acute Proctitis refers to inflammation of the rectal mucosa, typically presenting with rectal pain, tenesmus, urgency, and bleeding. It results from mucosal barrier disruption with activation of innate and adaptive immune responses, leading to oedema, ulceration, and increased vascular permeability. ⚠️ In UK practice, infection must always be excluded first, particularly sexually transmitted causes, before diagnosing inflammatory disease. Management should be aetiology-directed, not purely symptomatic.

📌 Causes of Acute Proctitis

🦠 Infective (commonest in young adults)
- Sexually transmitted: gonorrhoea, chlamydia (incl. LGV), HSV, syphilis
- Enteric: Campylobacter, Shigella, Salmonella
- Clostridioides difficile (post-antibiotics)
🔥 Inflammatory
- Ulcerative colitis (classically starts in rectum)
- Crohn’s disease (less commonly isolated)
☢️ Radiation-induced
- Post pelvic radiotherapy (prostate, cervical, rectal cancer)
💊 Drug / Chemical
- NSAIDs, rectal preparations, enemas, irritants
⚠️ Other
- Ischaemia (elderly/vascular disease)
- Trauma, foreign bodies
- Solitary rectal ulcer syndrome

🧠 Pathophysiology

Acute proctitis involves epithelial injury → immune activation → mucosal inflammation. In infection, pathogen invasion drives neutrophilic infiltration and ulceration. In inflammatory bowel disease, dysregulated T-cell and cytokine responses (e.g. TNF-α) perpetuate damage. Radiation causes endothelial injury, fibrosis, and ischaemia, impairing healing.

🔍 Clinical Features

Rectal pain, burning, discomfort
Tenesmus (incomplete evacuation sensation)
Rectal bleeding or mucus discharge
Urgency ± diarrhoea
Systemic symptoms (fever, malaise) if infective/severe

🧪 Investigation

🧫 Stool culture ± C. difficile toxin if diarrhoea
🧬 Rectal swabs for STI testing (essential in at-risk patients)
🩸 FBC, CRP, ESR
🧪 Consider HIV testing where appropriate
📸 Flexible sigmoidoscopy + biopsy if persistent, severe, or unclear diagnosis

💡 Clinical rule: Always exclude infection (especially STIs) before diagnosing IBD

💊 Management and Treatment

🦠 Infective
- Targeted antimicrobial therapy based on results
- Empirical STI treatment if high suspicion
- 👉 Refer to GUM clinic for testing, treatment, and contact tracing
🔥 Inflammatory (IBD)
- Topical mesalazine suppositories first-line (high efficacy)
- Topical steroids if inadequate response
- Escalate to oral/systemic therapy if extensive or refractory
☢️ Radiation
- Sucralfate enemas, topical steroids
- Endoscopic therapy for persistent bleeding
🧴 Supportive
- Analgesia, stool softeners, hydration
- Avoid rectal irritants

🚨 Red Flags (Urgent Referral)

Severe bleeding or haemodynamic instability
Systemic sepsis
⚠️ Suspicion of colorectal malignancy (weight loss, anaemia, change in bowel habit)
Failure to respond to initial therapy

🩸 Differential Diagnosis of Rectal Bleeding

Cause	Key Features	Typical Clues
Haemorrhoids 🟣	Painless bright red bleeding	Blood on paper, pruritus, no systemic symptoms
Anal fissure 🔪	Severe pain on defecation	Fresh blood, tearing pain, constipation history
Proctitis 🦠	Bleeding + tenesmus + urgency	Mucus, rectal pain, STI risk or IBD
Colorectal cancer 🎗️	Change in bowel habit + bleeding	Weight loss, iron deficiency anaemia ⚠️
Ulcerative colitis 🔥	Bloody diarrhoea	Chronic symptoms, urgency, systemic features
Crohn’s disease 🌿	Less overt bleeding	Abdominal pain, weight loss, perianal disease
Diverticular disease 💥	Painless large-volume bleeding	Elderly, sudden onset
Angiodysplasia 🧬	Intermittent bleeding	Elderly, associated with aortic stenosis
Infective colitis 🦠	Bloody diarrhoea + fever	Recent travel, food exposure
Ischaemic colitis ⚠️	Pain + bleeding	Older patient, vascular risk factors

📚 Key Learning Points

Acute proctitis is a symptom-based diagnosis requiring systematic evaluation. In UK practice, STI causes are common and must be excluded early. Topical therapy is highly effective in IBD due to direct mucosal delivery. Thinking mechanistically — epithelial injury, immune activation, and vascular compromise — helps guide targeted treatment and avoid misdiagnosis.

📚 References (UK Guidance)

NICE CKS – Diarrhoea: assessment of infective causes and stool testing
NICE NG12: Suspected cancer – recognition and referral (colorectal cancer red flags)
BASHH Guidelines: Management of sexually transmitted infections (gonorrhoea, chlamydia, HSV, syphilis)
NICE NG197: Ulcerative colitis – management (including topical mesalazine)
NICE QS161: Inflammatory bowel disease quality standard

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