Overview
Definition:
Sigmoidoscopy is an endoscopic procedure that allows visualization and examination of the distal part of the large intestine, specifically the rectum and sigmoid colon, using a flexible or rigid sigmoidoscope
In acute settings, it is primarily employed for rapid diagnosis and management of urgent gastrointestinal conditions affecting this region.
Epidemiology:
While specific incidence data for sigmoidoscopy in acute settings is limited, conditions necessitating it, such as acute lower GI bleeding and sigmoid volvulus, are common presentations in emergency departments and surgical wards across India
Factors like age, diet, and underlying colonic pathology influence prevalence.
Clinical Significance:
Sigmoidoscopy in acute situations offers direct visualization of mucosal integrity, active bleeding, or obstructive lesions
It aids in rapid decision-making for interventions like hemostasis, decompression, or surgical planning, significantly impacting patient outcomes and reducing diagnostic delays in critical scenarios.
Indications
Absolute Indications:
Active, brisk rectal bleeding
Suspected sigmoid volvulus
Acute diverticulitis with uncertainty or concern for complications
Foreign body in the distal rectum
Severe, unexplained rectal pain suggestive of local pathology.
Relative Indications:
Unexplained lower abdominal pain with suspicion of distal colonic involvement
Evaluation of proctitis or radiation proctitis
Staging of rectal tumors where immediate assessment is needed
Pre-operative assessment in specific acute scenarios.
Contraindications:
Perforation of the colon or rectum
Fulminant colitis or toxic megacolon (relative contraindication)
Severe hemodynamic instability
Inability to position the patient adequately
Recent rectal surgery or biopsy in the distal tract.
Diagnostic Approach
History Taking:
Detailed history of bleeding (color, quantity, frequency)
Onset and nature of pain
Bowel habit changes
Previous GI surgeries or procedures
Coagulation disorders
Medications (anticoagulants, NSAIDs)
Last bowel movement.
Physical Examination:
Abdominal examination for distension, tenderness, rigidity, or masses
Digital rectal examination (DRE) to assess for masses, blood, stool consistency, and anal tone
Assess vital signs for hemodynamic stability.
Pre Procedure Preparation:
In acute settings, preparation is often limited and tailored
For bleeding, minimal bowel prep may be used if stable
For suspected obstruction, contrast studies might precede endoscopy
IV access and resuscitation if hemodynamically compromised
Informed consent is crucial.
Endoscopic Technique:
Low-pressure insufflation with air or CO2
Careful, gentle insertion of the flexible sigmoidoscope
Retrograde examination of the mucosa for bleeding sites, ulcers, polyps, diverticula, or masses
Biopsies can be taken if indicated
Active bleeding may require immediate endoscopic hemostasis.
Management During Procedure
Hemostasis For Bleeding:
Identification of bleeding source
Application of epinephrine injection, thermal coagulation (bipolar cautery, argon plasma coagulation), or hemoclips
Angiodysplasias and small ulcers are common targets.
Decompression For Volvulus:
Gentle intubation of the sigmoidoscope through the twisted segment to decompress the lumen
Careful advancement and observation for resolution of distension
Stool may be evacuated
Release of pressure is critical.
Foreign Body Retrieval:
Visualization and identification of the foreign body
Use of appropriate endoscopic accessories (forceps, snares, retrieval baskets) for safe extraction
Caution to avoid mucosal injury or perforation.
Biopsy And Sampling:
Targeted biopsies of suspicious lesions, ulcers, or areas of inflammation
Histopathological examination provides definitive diagnosis for conditions like malignancy, inflammatory bowel disease, or infections.
Complications
Early Complications:
Perforation of the colon or rectum, especially with forceful insertion or in friable mucosa
Bleeding, particularly after biopsy or polypectomy
Discomfort or abdominal pain
Vasovagal syncope
Infection (rare).
Late Complications:
Stricture formation at the site of injury or intervention
Bleeding occurring hours to days after the procedure
Adhesions causing bowel obstruction (very rare).
Management Of Complications:
Perforation: Immediate surgical consultation, broad-spectrum antibiotics, fluid resuscitation, and surgical repair or resection
Bleeding: Resuscitation, repeat endoscopy, angiographic embolization, or surgical intervention if conservative measures fail
Pain: Analgesics and observation.
Prognosis
Factors Affecting Prognosis:
The underlying cause for which sigmoidoscopy was performed
Promptness and effectiveness of intervention
Presence of comorbidities
Development and management of complications
Skill of the endoscopist.
Outcomes:
For benign conditions like mild bleeding or proctitis, outcomes are generally excellent with appropriate management
For emergent situations like perforation or severe bleeding, outcomes depend heavily on timely intervention and management of complications.
Follow Up:
Follow-up depends on the diagnosis
Patients with active bleeding or inflammatory conditions require serial assessments and treatment
Those with strictures or post-operative recovery need close monitoring
Routine surveillance may be indicated for neoplastic findings.
Key Points
Exam Focus:
High-yield scenarios include management of acute lower GI bleed, diagnosis of sigmoid volvulus, and recognizing indications/contraindications in emergency settings
Remember the sequence of management for these conditions.
Clinical Pearls:
Always perform DRE before sigmoidoscopy if readily accessible in acute rectal issues
Gentle insufflation is paramount to prevent iatrogenic injury
Be prepared for immediate intervention for bleeding or volvulus decompression.
Common Mistakes:
Over-enthusiastic insufflation leading to perforation
Failure to recognize absolute contraindications
Inadequate preparation in non-emergent elective cases (though less relevant in true acute scenarios)
Delayed surgical consultation when endoscopic intervention fails or is not feasible.