Colonic Polyps

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Referral

Definition

Colonic polyps are abnormal tissue growths that protrude from the inner lining of the colon or rectum. They can be benign but may have the potential to become malignant over time.

Aetiology

Colonic polyps are classified based on histology:

  • Adenomatous polyps (neoplastic): can develop into colorectal cancer (CRC); includes tubular, villous, and tubulovillous adenomas.
  • Hyperplastic polyps (non-neoplastic): common and generally benign but may be associated with the serrated pathway to CRC.
  • Sessile serrated polyps (SSPs): precancerous with potential for malignancy.
  • Inflammatory polyps: occur in conditions such as inflammatory bowel disease (IBD), particularly ulcerative colitis.
  • Hamartomatous polyps: associated with genetic syndromes such as Peutz-Jeghers syndrome.

Pathophysiology

  • Genetic mutations (e.g., APC gene mutation in adenomas) lead to uncontrolled cell growth.
  • Chronic inflammation (e.g., in IBD) can contribute to polyp formation.
  • Progression from adenomatous polyps to colorectal cancer follows the adenoma-carcinoma sequence over 5–10 years.

Risk factors

  • Age >50 years.
  • Family history of colorectal cancer or polyps.
  • Genetic syndromes (e.g., familial adenomatous polyposis, Lynch syndrome).
  • Inflammatory bowel disease (ulcerative colitis or Crohn’s colitis).
  • Diet high in red and processed meats.
  • Smoking and excessive alcohol intake.
  • Obesity and sedentary lifestyle.

Signs and symptoms

Symptoms:

  • Usually asymptomatic and detected incidentally on screening.
  • Rectal bleeding or blood in stool (may be occult).
  • Change in bowel habits (e.g., diarrhoea or constipation).
  • Iron deficiency anaemia (if chronic blood loss occurs).
  • Abdominal pain (if large polyps cause obstruction).

Signs:

  • Most patients have no specific findings on examination.
  • Palpable rectal polyp on digital rectal examination (if low-lying).
  • Signs of anaemia (pallor, tachycardia) if chronic bleeding is present.

Investigations

  • Colonoscopy (gold standard): identifies and removes polyps for histological analysis.
  • Faecal immunochemical test (FIT): detects occult blood in stool, used in bowel cancer screening.
  • CT colonography: alternative for patients unsuitable for colonoscopy.
  • Histology: determines polyp type and malignancy risk.

Management

1. Polyp Removal:

  • Endoscopic polypectomy: removal via colonoscopy (e.g., snare excision or biopsy forceps).
  • Endoscopic mucosal resection (EMR): for larger sessile polyps.
  • Surgical resection: required if malignancy is suspected or polyps are too large for endoscopic removal.

2. Surveillance and Prevention:

  • Follow-up colonoscopy based on polyp histology and number:
    • Low-risk adenomas: repeat in 5 years.
    • High-risk adenomas (large, villous, multiple): repeat in 3 years.
    • Serrated polyps: more frequent surveillance required.
  • Lifestyle modification: increase fibre intake, reduce red meat consumption, maintain healthy weight.
  • Consider aspirin for high-risk patients (e.g., Lynch syndrome) to reduce colorectal cancer risk.

Referral

  • Routine referral: for asymptomatic patients with detected polyps requiring surveillance.
  • Urgent referral: if malignant features are suspected (e.g., large, ulcerated polyps).
  • Genetic referral: if multiple polyps or family history suggests hereditary polyposis syndromes.
GastroenterologymypanotesColonic Polyps