Overview
Definition:
An anal stricture is a pathological narrowing of the anal canal, leading to impaired passage of stool
It can range from a mild circumferential narrowing to a severe, almost complete occlusion
This condition significantly impacts quality of life due to symptoms like painful defecation, straining, and incomplete evacuation
Anal strictures can be benign or malignant, necessitating accurate diagnosis and appropriate management.
Epidemiology:
The exact incidence of anal strictures is not well-documented due to varying definitions and reporting methods
However, common causes include surgical trauma (e.g., fistulotomy, sphincterotomy, hemorrhoidectomy), inflammatory bowel disease (especially Crohn's disease affecting the perianal region), radiation therapy to the pelvis, chronic infection (e.g., tuberculosis, granulomatous proctitis), and, rarely, malignancy
Fibrosis and scar formation are the underlying pathological processes.
Clinical Significance:
Anal strictures pose a significant challenge in surgical practice
Unmanaged, they can lead to chronic constipation, fecal impaction, rectoanal intussusception, recurrent anal fissures, perianal sepsis, and fistulas
In the context of DNB and NEET SS examinations, understanding the etiology, diagnostic workup, and varied management strategies, including non-operative and operative interventions, is crucial for residents to effectively manage these patients and demonstrate competence in colorectal surgery.
Clinical Presentation
Symptoms:
Difficulty passing stools (obstipation)
Straining during defecation
Sensation of incomplete evacuation
Pencil-thin stools (scybalous stools)
Pain or bleeding during defecation (dyschezia)
Perianal discomfort or itching
Recurrent episodes of constipation and diarrhea
Fecal incontinence in severe cases
Abdominal distension or bloating.
Signs:
On digital rectal examination (DRE), a palpable narrowing of the anal canal lumen is noted
The degree of narrowing can be assessed
In severe cases, DRE may be difficult or impossible
Associated findings may include perianal skin tags, fissures, fistulas, or signs of inflammatory bowel disease
Rectal prolapse can sometimes coexist.
Diagnostic Criteria:
There are no formal diagnostic criteria like those for some systemic diseases
Diagnosis is primarily clinical, based on patient history, digital rectal examination, and supported by anoscopy, rectoscopy, or proctoscopy findings
Imaging modalities like manometry, endoanal ultrasound, and MRI may aid in assessing the extent of the stricture and associated pathology.
Diagnostic Approach
History Taking:
Detailed history of any previous anal or rectal surgery, including the type of procedure and complications
History of inflammatory bowel disease (Crohn's, Ulcerative Colitis) with perianal involvement
History of pelvic radiation therapy for malignancies
Duration and progression of symptoms
Pattern of bowel movements
Presence of pain, bleeding, or tenesmus
Previous treatments and their efficacy
Red flags include weight loss, blood in stool not explained by fissures, and a history of malignancy.
Physical Examination:
A thorough abdominal examination to assess for distension or tenderness
Careful inspection of the perianal area for skin tags, fissures, fistulas, or signs of infection
Digital rectal examination (DRE) is paramount to assess the anal tone, patency of the anal canal, and the presence and length of any stricture
Anoscopy and rigid rectoscopy are essential to visualize the anal canal and distal rectum, assess the nature and length of the stricture, and rule out internal hemorrhoids, fissures, polyps, or neoplastic lesions.
Investigations:
Anoscopy/Proctoscopy: Essential for direct visualization
Anal manometry: Assesses anal sphincter tone and rectal sensation, helpful in evaluating functional impact
Endoanal Ultrasound: Can assess sphincter integrity and the depth of stricture, particularly useful in post-surgical or inflammatory strictures
MRI Pelvis: Useful for evaluating the extent of stricture, associated fistulas, abscesses, or to rule out malignancy, especially in post-radiation patients
Colonoscopy: Indicated to rule out proximal colonic pathology, synchronous colorectal cancer, or inflammatory bowel disease
Biopsy: Crucial if malignancy is suspected during endoscopy.
Differential Diagnosis:
Severe anal fissure with secondary fibrosis
Anal cancer
Proctitis (infectious or inflammatory)
Rectal prolapse
Post-surgical scarring from hemorrhoidectomy or other anal procedures
Diverticulitis with rectal involvement
Foreign body in the rectum.
Management
Initial Management:
Conservative management is the first line for mild to moderate strictures
This includes dietary modifications (high-fiber diet), adequate fluid intake, and stool softeners (e.g., docusate sodium, psyllium husk)
Laxatives (e.g., polyethylene glycol) can help maintain regular bowel movements and reduce straining
Regular digital dilatation or the use of anal dilators under medical guidance can also be beneficial.
Medical Management:
Primarily supportive and symptomatic
Stool softeners and osmotic laxatives are key to prevent straining and facilitate passage of stool
Antibiotics may be indicated if there is evidence of infection or perianal sepsis associated with the stricture
Topical treatments for associated anal fissures or skin irritation might be used.
Surgical Management:
Surgical intervention is reserved for symptomatic patients who fail conservative therapy, or for those with severe strictures, significant symptoms, or complications
Options include: 1
Anal dilators: Gradual dilatation under anesthesia
2
Dilation and Anoplasty: Mechanical dilation followed by radial incision of the stricture with a plastic procedure to widen the anal canal, often with local flaps (e.g., V-Y advancement flap, local mucosal flaps)
3
Sphincterotomy: For distal, non-circumferential strictures, a partial internal or external sphincterotomy may be performed to relieve pressure and facilitate healing
4
Diversion: In cases of severe, long-standing strictures with severe sepsis or inability to perform definitive reconstruction, a temporary or permanent colostomy may be necessary
5
Resection: For strictures due to malignancy or extensive fibrosis unresponsive to other measures, proctectomy with stoma may be the only option.
Supportive Care:
Post-operative care involves pain management, wound care (sitz baths), and stool softeners to prevent straining
Nutritional support is important, especially for patients with underlying inflammatory bowel disease
Long-term follow-up is essential to monitor for recurrence and manage any complications.
Complications
Early Complications:
Bleeding
Pain
Infection
Sepsis
Wound dehiscence
Fistula formation
Urinary retention
Fecal incontinence (temporary or permanent).
Late Complications:
Stricture recurrence is a significant concern
Chronic pain
Persistent fecal soiling
Rectal prolapse
Development of rectoanal intussusception
Anal stenosis requiring revision surgery.
Prevention Strategies:
Minimizing aggressive surgical techniques in the anal canal whenever possible
Gentle handling of tissues during surgery
Appropriate management of post-operative wounds
Judicious use of radiation therapy to the pelvic region
Early and effective management of inflammatory bowel disease and perianal sepsis.
Prognosis
Factors Affecting Prognosis:
The etiology of the stricture is a major determinant of prognosis
Malignant strictures have a poorer prognosis than benign ones
The length and severity of the stricture, the presence of associated sepsis or fistulas, the patient's overall health status, and the skill of the surgeon also influence outcomes
Recurrent strictures generally have a worse prognosis.
Outcomes:
With timely and appropriate management, many patients with benign anal strictures can achieve symptomatic relief and a significant improvement in their quality of life
Conservative management can be successful for mild strictures
Surgical management offers a higher success rate for more severe or refractory cases, but recurrence remains a possibility
Malignant strictures require oncological treatment, and prognosis depends on the stage.
Follow Up:
Regular follow-up is crucial, especially after surgical intervention, to monitor for recurrence, assess wound healing, and manage any long-term sequelae
This typically involves clinical examination and digital rectal examination at regular intervals for at least one year, and then as needed
Patients should be educated about early signs of recurrence.
Key Points
Exam Focus:
Etiology (iatrogenic, IBD, radiation)
Diagnostic modalities: DRE, anoscopy, rectoscopy, manometry, endoanal ultrasound, MRI
Management ladder: Conservative -> Dilators -> Anoplasty/Flaps -> Diversion/Resection
Risk of recurrence
Differentiating benign vs
malignant strictures.
Clinical Pearls:
Always perform a thorough digital rectal examination to assess stricture length and anal tone
Suspect malignancy in new-onset strictures in elderly patients or those with a history of IBD or radiation
Post-radiation strictures are notoriously difficult to treat surgically and have a higher recurrence rate
Consider anal manometry to assess sphincter function before and after surgery
Aggressive stool softeners are your best friend in conservative management.
Common Mistakes:
Underestimating the severity of the stricture on DRE
Failing to adequately investigate for underlying malignancy or proximal colonic pathology
Aggressive surgical intervention without optimizing conservative measures
Inadequate post-operative follow-up leading to undetected recurrence
Misinterpreting imaging findings without correlation with clinical presentation.