Overview
Definition:
Colonoscopy is an endoscopic procedure that allows direct visualization of the entire colonic mucosa using a flexible, lighted instrument (colonoscope)
It is crucial for the diagnosis and management of various colorectal pathologies, including the detection and removal of polyps, which are precancerous lesions
Bowel preparation is a critical prerequisite for optimizing visualization during the procedure
Polypectomy is the endoscopic removal of colonic polyps, a cornerstone of colorectal cancer prevention.
Epidemiology:
Colorectal cancer is a leading cause of cancer-related deaths globally, with incidence rates varying geographically
Screening colonoscopies have significantly reduced mortality by detecting and removing precancerous polyps
The prevalence of colorectal polyps increases with age, typically above 40 years
Approximately 25-30% of individuals undergoing screening colonoscopy will have polyps.
Clinical Significance:
Adequate bowel preparation is paramount for a successful colonoscopy, enabling the identification of subtle lesions and preventing procedure cancellations or repeat examinations
Effective polypectomy is the most direct method of preventing colorectal cancer by removing adenomatous polyps before they undergo malignant transformation
Proficiency in these techniques is essential for all surgical residents preparing for board examinations like DNB and NEET SS.
Bowel Preparation
Indications:
Required for all elective colonoscopies and sigmoidoscopies
Essential for accurate mucosal visualization, enabling detection of polyps, early cancers, and inflammatory changes
Crucial for safe and effective polypectomy and other endoscopic interventions.
Agents:
Polyethylene glycol (PEG)-based solutions (e.g., PEG-ELS, PEG-electrolyte solution): Most common, isosmolars, effective, generally safe
Sodium picosulfate/magnesium citrate combinations: Stimulant laxatives, effective, may cause electrolyte disturbances in some patients
Sodium phosphate preparations: Hyperosmolar, rapid action, but associated with renal toxicity and electrolyte imbalances, generally avoided in patients with renal insufficiency, cardiac failure, or dehydration
Split-dosing regimens (e.g., half the evening before, half the morning of procedure) significantly improve compliance and quality of prep compared to single-dose regimens
Clear liquid diet 24-48 hours prior is also a key component.
Protocols:
Low-residue diet 2-3 days prior to the procedure
Clear liquid diet on the day before the procedure (avoid red, blue, or purple liquids)
Administration of bowel prep agent: Typically split-dose regimen (e.g., 2L PEG solution the evening before, 2L morning of procedure, spaced 2-4 hours apart)
Adequate hydration with clear fluids is essential throughout the prep
Patients should be instructed on signs of dehydration and when to contact their physician.
Assessment Of Prep Quality:
The Boston Bowel Preparation Scale (BBPS) is the most widely used validated scale
A score of 6-7 is considered adequate for most procedures, while 8-9 indicates excellent prep
Factors assessed include the amount of residual fluid, presence of solid fecal matter, and ease of visualization of the mucosa
Poor prep can lead to missed lesions and incomplete examinations.
Polypectomy
Indications:
Removal of all identified colorectal polyps to prevent colorectal cancer
Management of sessile serrated lesions (SSLs) and traditional serrated adenomas (TSAs)
Diagnostic sampling of suspicious mucosal lesions
Treatment of small superficial submucosal tumors.
Techniques:
Cold snare polypectomy (CSP): Used for smaller polyps (<10mm), especially those in distal locations, and for certain sessile polyps
Advantages include lower risk of post-polypectomy bleeding and perforation
Hot snare polypectomy (HSP): Used for larger polyps (>10mm) or those with a broader stalk
Electrocoagulation heats the tissue, aiding in cutting and achieving hemostasis
Endoscopic mucosal resection (EMR): For larger, flat, or sessile polyps that cannot be safely removed with a snare alone
Involves injecting a fluid cushion submucosally to lift the lesion, followed by snare excision
Endoscopic submucosal dissection (ESD): Technically demanding procedure for large, advanced flat lesions or early submucosal cancers
not typically performed by general surgical residents.
Equipment:
Polypectomy snares (diathermic/hot, cold, different sizes and shapes - loop, oval, rectangular)
Electrosurgical generators (for hot snare and EMR)
Injection needles and solutions (saline, methylene blue, indigo carmine)
Retrieval devices (e.g., graspers, biopsy forceps) for specimen retrieval
Specimen containment bags.
Management Of Different Polyp Types:
Adenomas: Standard resection via snare or EMR depending on size and morphology
Sessile Serrated Lesions (SSLs): Careful removal is crucial due to potential for rapid malignant transformation
Often require EMR for complete eradication, especially if flat or large
Hyperplastic polyps (distal colon): Generally do not require removal unless large or in proximal colon where diagnosis is uncertain
Submucosal lesions: Require biopsy to determine histology before considering EMR or ESD.
Preoperative Considerations
Patient Assessment:
History of bleeding disorders, coagulopathy, anticoagulant/antiplatelet use
Previous bowel surgeries or radiotherapy
Significant comorbidities (cardiac, renal, pulmonary)
Allergies to medications
Patient understanding and consent for the procedure and potential complications.
Medication Management:
Anticoagulants (e.g., warfarin, DOACs): typically stopped 3-7 days prior based on agent and indication
Antiplatelets (e.g., aspirin, clopidogrel): often continued for high-risk patients (e.g., recent stent placement) but may be stopped after discussion with cardiologist
Bridging therapy with heparin may be considered for high-risk patients on warfarin
All medications should be reviewed and adjusted according to institutional protocols and surgeon preference.
Informed Consent:
Detailed explanation of the procedure, including benefits, risks (perforation, bleeding, infection, missed lesions, sedation-related risks), and alternatives
Specific risks associated with polypectomy (bleeding, delayed perforation, thermal injury)
Discussion of the bowel preparation process and its importance.
Postoperative Care And Follow Up
Immediate Postprocedure:
Observation for vital signs, pain, and signs of bleeding or perforation
Hydration and diet advancement as tolerated
Patients on anticoagulants may require delayed reinitiation based on procedure complexity and bleeding risk.
Discharge Instructions:
Dietary recommendations (gradual return to normal diet)
Activity restrictions (avoid strenuous activity for 24-48 hours)
Signs and symptoms of complications to report (severe abdominal pain, fever, vomiting, rectal bleeding)
Instructions for resuming medications
Follow-up appointment for results and surveillance recommendations.
Surveillance Guidelines:
Follow-up intervals depend on the number, size, and histology of polyps removed
National Comprehensive Cancer Network (NCCN) guidelines provide recommendations: e.g., 1 year for adequate resection of multiple adenomas or large sessile polyps
3-5 years for patients with few small adenomas
Regular surveillance colonoscopies are crucial for early detection of recurrent polyps or new malignancies.
Complications
Immediate Complications:
Perforation: Risk is higher with large polyps, hot snare polypectomy, and in patients with inflammatory bowel disease
Can be subtle and require surgical intervention
Bleeding: Can occur immediately or delayed (up to 2 weeks)
Management ranges from observation to endoscopic hemostasis or surgical intervention
Sedation-related complications: Respiratory depression, aspiration, cardiac events.
Delayed Complications:
Post-polypectomy syndrome: Abdominal pain, fever, and leukocytosis without evidence of perforation, often managed conservatively
Delayed bleeding: Can occur up to 2 weeks post-procedure
Stricture formation: Rare complication of extensive polypectomy or EMR, especially in the rectum
Infection: Rare but possible, especially if bowel prep is inadequate or in immunocompromised patients.
Prevention Strategies:
Meticulous bowel preparation is key
Careful endoscopic technique during polypectomy, especially with hot biopsy forceps and for larger or flat lesions
Use of appropriate snare and electrosurgical settings
Considering EMR for larger or challenging polyps
Patient selection and optimization of comorbidities
Clear communication of post-procedure instructions and diligent follow-up.
Key Points
Exam Focus:
Understand the role of bowel preparation quality (BBPS) in colonoscopy success
Differentiate indications and techniques for cold snare, hot snare, and EMR
Recognize complications of colonoscopy and polypectomy and their management
Recall surveillance guidelines based on polyp findings
DNB and NEET SS exams frequently test these practical aspects.
Clinical Pearls:
Split-dose bowel prep is superior
Always confirm adequate prep before proceeding with colonoscopy
For sessile serrated lesions, achieve complete mucosal resection, often requiring EMR
For large polyps, submucosal injection for lifting (EMR) is crucial
Always have irrigation and cautery readily available
Inform patients about the possibility of delayed bleeding and when to seek help.
Common Mistakes:
Inadequate bowel prep leading to missed lesions
Incomplete polypectomy, especially for sessile serrated lesions
Over-reliance on hot biopsy forceps for larger polyps, increasing perforation risk
Mismanagement of anticoagulation pre-procedure
Failure to adhere to recommended surveillance intervals after polyp removal.