Perianal Crohn Disease

Perianal Crohn disease includes abscesses, fistulas, fissures, ulcers, stenosis and destructive anorectal inflammation caused by transmural Crohn disease.

Complex fistulating disease requires coordinated control of both perianal sepsis and luminal inflammation.

Closing a fistula while leaving an undrained abscess behind can precipitate severe sepsis.

Drain every clinically significant abscess before starting or escalating major immunosuppressive fistula therapy.

For complex fistulas, establish drainage with a loose seton before definitive medical or surgical closure. Chronic seton drainage alone should not be considered definitive treatment except for palliation.

Antibiotics can control acute perianal sepsis but do not reliably close Crohn fistulas by themselves.

A practical short course when infection is present is:

Ciprofloxacin 500 mg orally twice daily

with or without

Metronidazole 500 mg orally two to three times daily, depending on severity and microbiology.

For established complex fistulating disease after sepsis control:

Infliximab 5 mg/kg IV at weeks 0, 2 and 6, then every 8 weeks is a major first line biologic strategy.

A simple low fistula in a patient without proctitis and with good continence can occasionally undergo fistulotomy.

Avoid fistulotomy through substantial sphincter in complex disease.

After luminal disease control, suitable fistulas can undergo LIFT or advancement flap closure.

Avoid cutting setons because of sphincter injury and incontinence risk.

Severe refractory anorectal disease with uncontrollable sepsis, destructive proctitis or intolerable symptoms may ultimately require faecal diversion or proctectomy.

Clinical toolsCalculators

BMI GCS EDD Parkland Formula

Corrected Sodium Corrected Calcium Anion Gap Creatinine Clearance Insulin Calculations qSOFA Wells PE Wells DVT CHA₂DS₂-VASc HAS-BLED CURB-65 Centor/McIsaac

Toxic Megacolon

Toxic megacolon is acute nonmechanical colonic dilatation associated with severe systemic toxicity.

It most often complicates ulcerative colitis, Crohn colitis or severe infectious colitis, particularly Clostridioides difficile.

Colonic diameter is generally at least 5.5 to 6 cm, accompanied by systemic toxicity. Progressive mural inflammation and loss of smooth muscle tone place the colon at high risk of perforation.

Admit to a monitored setting and involve colorectal surgery immediately.

Stop opioids, anticholinergic agents, antimotility drugs and other medications that worsen colonic dilatation.

Correct fluid, potassium, magnesium and other electrolyte deficits. Provide pharmacological venous thromboembolism prophylaxis unless contraindicated.

If ulcerative colitis is the underlying cause and perforation or uncontrolled infection is not present:

Methylprednisolone 60 mg IV daily

Hydrocortisone 100 mg IV every 6 hours.

Do not continue ineffective steroid treatment while the patient deteriorates.

Toxic megacolon with worsening systemic toxicity, perforation, uncontrolled haemorrhage, increasing dilatation or failure of rapid medical improvement requires urgent total abdominal colectomy with end ileostomy, leaving the rectum for later staged management.

When fulminant Clostridioides difficile infection is responsible, treat with:

Vancomycin 500 mg orally or through nasogastric tube every 6 hours

plus

Metronidazole 500 mg IV every 8 hours.

With major ileus preventing effective colonic drug delivery, add rectal vancomy according to local critical care protocol.

Do not delay colectomy in a deteriorating patient because antimicrobial or immunosuppressive rescue is being attempted.

Perianal Crohn Disease

Overview

Clinical Features

Diagnosis

Management

Overview

Clinical Features

Diagnosis

Management