ConditionDigestive system
Rectal Stricture
A rectal stricture is an abnormal narrowing of the rectum, the last part of the large bowel before the anus. Scar tissue, inflammation or a tumor reduces the width of the passage, so stools become thin, difficult and painful to pass. Common causes are previous bowel surgery, Crohn's disease, radiation therapy and, importantly, rectal cancer, which must always be ruled out. Most benign strictures are treated by gently stretching (dilating) the narrowed segment; some need surgery.
Also called: Rectal stenosis, anorectal stricture, narrowing of the rectum, anastomotic stricture (after surgery)
At a glance
- What it is
- A narrowing of the rectum from scarring, inflammation or a growth.
- Main causes
- Bowel surgery joins, Crohn's disease, radiation, ischemia, infections, and rectal cancer.
- Symptoms
- Straining, thin or ribbon-like stools, a feeling of incomplete emptying, pain, bleeding and bloating.
- Diagnosis
- Rectal exam, sigmoidoscopy or colonoscopy with biopsies, and MRI or CT.
- Treatment
- Stool softeners, balloon dilation, steroid injection, stents, and surgery for resistant or cancerous strictures.
When to get help
Call 911 or go to the ER
- No stool or gas passed for more than 24 hours with a swollen, painful belly and vomiting (possible bowel obstruction)
- Heavy rectal bleeding, or bleeding with dizziness or fainting
- Severe belly pain and fever after a dilation procedure (possible perforation)
See a doctor within a day or two
- Increasing difficulty passing stools over days, with bloating and cramps
- Rectal bleeding with a change in bowel habit, especially over age 45
- Fever and rectal pain with discharge
Book a routine appointment
- Stools that have become persistently thin, narrow or ribbon-like
- A feeling of incomplete emptying or needing to strain more than usual for several weeks
- Unexplained weight loss or anemia with bowel symptoms
What a rectal stricture is
The rectum is a stretchy tube about 12 to 15 cm (5 to 6 in) long that stores stool until you are ready to pass it. When its wall is damaged, healing can lay down stiff, fibrous scar tissue that contracts and narrows the passage. A tumor can also grow into the lumen and narrow it from within.
Strictures are described as:
- benign or malignant (cancerous)
- short or long, which affects treatment options
- rectal or anorectal, if the narrowing extends into the anal canal (anal stenosis)
Symptoms
- Straining and difficulty passing stools (constipation)
- Stools that are thinner than usual, pencil-thin or ribbon-shaped
- Feeling that the bowel has not emptied (tenesmus)
- Pain during bowel movements
- Bloating and crampy belly pain
- Bleeding or mucus from the rectum
- Overflow leakage of liquid stool around the narrowing
- With severe narrowing, signs of bowel obstruction
Thin stools alone are often caused by temporary constipation or irritable bowel syndrome, but persistently thin stools with other symptoms need a check.
Causes
| Cause | Clues |
|---|---|
| After surgery (anastomotic stricture) | Narrowing at the join after removing part of the rectum or colon, common after low anterior resection, often within months |
| Crohn's disease | Inflammation of the whole bowel wall; often with perianal fistulas or abscesses |
| Ulcerative colitis | Benign strictures uncommon; a stricture in long-standing UC needs careful biopsy for cancer |
| Radiation therapy | Months to years after pelvic radiotherapy for prostate, cervical or rectal cancer |
| Ischemia | Reduced blood supply, for example after aortic surgery |
| Infections | Lymphogranuloma venereum (a chlamydia strain), tuberculosis, and others |
| Hemorrhoid surgery | Anal and low rectal narrowing, especially after extensive tissue removal |
| Colorectal cancer | Progressive narrowing, bleeding, weight loss, anemia |
| Other | Long-term laxative or suppository use (rare), diverticular disease of the sigmoid colon, endometriosis |
How it is diagnosed
- Digital rectal exam: a gloved finger can feel low strictures and assess how tight they are.
- Flexible sigmoidoscopy or colonoscopy: a camera examines the narrowing and the bowel above it. Biopsies are taken to rule out cancer and look for Crohn's disease or infection.
- MRI of the pelvis: shows how long and thick the stricture is, and detects fistulas and abscesses.
- CT scan: if obstruction, cancer spread or complications are suspected.
- Contrast enema: an X-ray with contrast liquid outlines the length and shape of the narrowing.
- Blood and stool tests: blood count for anemia, inflammation markers, and tests for infections such as chlamydia when relevant.
Treatment
Treatment depends on the cause, length and severity of the narrowing.
Treating the cause
- Medicines to control active Crohn's disease, such as biologics, which can ease inflammatory strictures
- Antibiotics for infections such as lymphogranuloma venereum
- Cancer treatment (surgery, chemotherapy and radiation) for malignant strictures
Stool management
Soluble fiber supplements, stool softeners and adequate fluids keep stools soft enough to pass through a mild narrowing. Avoid bulky, insoluble fiber if the narrowing is tight, as it can cause blockage.
Dilation
- Endoscopic balloon dilation: a balloon is passed through the stricture during a colonoscopy and inflated to stretch it. It is the first-line treatment for short benign strictures (under about 4 to 5 cm). Several sessions are often needed.
- Bougie or finger dilation: for low anorectal strictures, sometimes continued at home with graduated dilators.
- Steroid injection into the stricture before dilation is sometimes used to reduce recurrence.
- The main risk is perforation (a tear), which occurs in a small percentage of procedures.
Other endoscopic options
- Stricturotomy: cutting the scar tissue with an electrosurgical knife
- Stents: removable stents for benign strictures in selected cases, or to relieve obstruction from cancer
Surgery
Considered when dilation fails, the stricture is long, or cancer is present. Options include stricturoplasty (widening without removing bowel), removal of the narrowed segment with rejoining, anoplasty for anal narrowing, and, in severe cases, a stoma (colostomy or ileostomy).
Outlook
Benign strictures after surgery usually respond well to one or more dilations. Strictures from Crohn's disease and radiation are more likely to recur and may need repeated treatment or surgery. The outlook for malignant strictures depends on the cancer's stage.
Frequently asked questions
What does a rectal stricture feel like?
Most people notice increasing difficulty and straining to pass stools, thin or ribbon-like stools, and a feeling that the bowel has not fully emptied. There may be pain during bowel movements, bloating, cramping, bleeding or mucus.
Are pencil-thin stools a sign of cancer?
They can be, but usually are not. Thin stools are often caused by constipation, irritable bowel syndrome or hemorrhoids. Persistently thin stools, especially with bleeding, weight loss, anemia or age over 45, should be checked with a colonoscopy to rule out a narrowing from cancer.
Can a rectal stricture heal on its own?
A stricture caused by active inflammation may improve when the inflammation is treated, for example with Crohn's disease medicines. Scar-tissue strictures do not usually go away without treatment, but many respond well to balloon dilation.
How is a rectal stricture stretched?
During a colonoscopy or sigmoidoscopy, a deflated balloon is passed into the narrowing and inflated for a short time to stretch it. This is done under sedation. Low strictures can be stretched with graduated dilators. Repeat sessions are common.
Is surgery always needed for a rectal stricture?
No. Most benign strictures are managed with stool softeners and endoscopic dilation. Surgery is reserved for strictures that keep coming back, are long or complex, cause obstruction, or are caused by cancer.
Sources
This guide was written from current patient and clinical guidance, including:
- American Society of Colon and Rectal Surgeons (ASCRS): Clinical practice guidelines
- American Society for Gastrointestinal Endoscopy (ASGE): Guideline on the role of endoscopy in the management of benign colorectal strictures
- Crohn's & Colitis Foundation: Strictures
- MedlinePlus: Rectal disorders
- StatPearls (NCBI Bookshelf): Anal Stenosis