saudigastro.com/patients/perianal-crohns-disease
Category
Chronic
Red flags
5
This article is educational and does not replace your doctor's advice. Seek urgent care for any red-flag symptoms.
What is it?
Crohn's disease can affect any part of the digestive tract, including the area around the anus. Perianal disease includes anal fissures (cracks), abscesses (painful collections of pus), fistulas (abnormal tunnels connecting the bowel to the skin or to another organ), skin tags, and narrowing of the anal canal. It can occur with or without Crohn's inflammation higher up in the bowel.
How common is it?
Perianal disease affects a meaningful share of people with Crohn's disease at some point, and is more frequent when the rectum is inflamed. It can be the first sign of Crohn's disease in some people.
Why does it happen?
The cause is the same immune-driven inflammation that causes Crohn's disease elsewhere. Deep ulcers in the rectum or anal canal can tunnel through the bowel wall and form fistulas, and trapped infection forms abscesses. Smoking is linked with worse Crohn's disease and is worth stopping.
Symptoms
- Pain, swelling or a lump near the anus
- Pus, blood or mucus draining from an opening beside the anus
- Pain on sitting or passing stool
- Itching, irritation or skin tags around the anus
- Passing gas or stool from the vagina or urine with gas (with certain fistulas)
- Leakage of stool or difficulty controlling it
Red flags — seek urgent medical care
Fast-growing painful swelling near the anus with fever or chills
Likely an abscess needing urgent drainage. Go to the emergency department.
Severe pain that prevents sitting, or redness spreading on the skin
The infection may be spreading. Seek urgent care.
Fever, fast heartbeat or feeling very unwell with an anal problem
May indicate serious infection in the blood. Emergency care needed.
Stool or gas passing from the vagina, or new urinary infections with gas
Suggests a fistula to another organ. See your specialist soon.
A non-healing ulcer or a hard lump that grows over time
Long-standing disease can rarely develop cancer, so have it checked.
How is it diagnosed?
Diagnosis involves an examination of the area, sometimes under anaesthesia for accuracy. MRI of the pelvis is the best imaging test to map fistulas and abscesses. Endoanal ultrasound can also help. A colonoscopy checks whether Crohn's disease is active in the rectum and bowel, because treatment depends on this.
What the latest science says
Current guidelines support a combined approach: control any abscess surgically, then treat the underlying inflammation with medicines, often biologic therapy, sometimes with antibiotics as a bridge. Research on stem-cell injections for complex fistulas is ongoing, and availability varies.
Outlook — what to expect
Perianal Crohn's disease is often long-lasting, with periods of improvement and relapse. Many fistulas improve or close with modern combined treatment, though some persist and need long-term management. Early specialist care lowers the risk of complications and the need for major surgery.
Treatment
Habits & Lifestyle
Gentle daily care and healthy habits help symptoms and healing.
- Keep the area clean with water and gentle, unscented cleansing; pat dry rather than rubbing.
- Warm sitz baths (sitting in shallow warm water) can ease pain.
- Stop smoking; it makes Crohn's disease worse.
- Use pads for drainage, and avoid tight clothes.
- Do not squeeze or try to drain a swelling yourself.
Diet
No diet cures perianal disease, but avoiding both diarrhea and constipation reduces irritation.
- Aim for soft, well-formed stools; adjust fibre according to what your team advises.
- Drink enough fluids.
- Keep a food diary to notice foods that trigger loose stools.
- Ask for a dietitian review if you are losing weight or avoiding many foods.
Medications
Medicines aim to control Crohn's inflammation and help fistulas heal.
- Biologic medicines (anti-TNF drugs and others) are often the main treatment for fistulas; your specialist chooses which.
- Antibiotics may be used for infection or as short-term support.
- Immunomodulators may be added to biologics in some cases.
- Pain relief and creams for local comfort can be prescribed.
- Do not stop treatment without discussing it, even when symptoms improve.
Procedures & Surgery
Surgery treats infection and protects the sphincter muscles that control stool.
- Abscesses are drained surgically; this brings relief quickly.
- A seton (a soft thread placed through the fistula) keeps it draining and prevents repeat abscesses while medicines work.
- Once inflammation is controlled, selected fistulas may be closed with flaps, plugs or stem-cell injection.
- Dilation can help narrowing; a temporary stoma may be considered for severe disease to let tissue heal.
- Your surgeon will aim to protect continence, so stool control is preserved as much as possible.
Living with the condition
- A team approach (gastroenterologist, colorectal surgeon, radiologist, nurse) gives the best results.
- Living with drainage and pain can affect mood, intimacy and work; tell your team, as support is available.
Questions to ask your doctor
Save this list or print it before your appointment — doctors appreciate prepared patients.
- What type of fistula or abscess do I have, and what does the MRI show?
- Which medicine is best for my fistula, and how long before it works?
- Do I need a seton or other surgery?
- Will treatment affect my ability to control stool?
- Does this affect plans for pregnancy or childbirth?
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Status: Approved for publication by SGA; individual clinician review is ongoing · Published 24/04/2026
For general education only; it does not replace your doctor’s advice. Individual clinician review of this guide is ongoing. SGA clinician? Review this guide