What is the diagnostic approach for rectal prolapse?

Diagnosing Rectal Prolapse

The diagnosis of rectal prolapse is primarily based on careful clinical examination, with imaging studies reserved for cases where clinical evaluation is difficult or inadequate, or when patients have persistent symptoms after treatment. 1

Clinical Examination

Physical Examination

• Direct visualization of the prolapse during straining is the most definitive diagnostic method
• Differentiate between complete rectal prolapse and other conditions:
  • Complete rectal prolapse: circumferential, full-thickness protrusion of rectum through anus
  • Prolapsed hemorrhoids: radial bulging of discrete anal cushions (not concentric) 1
• Ask patient to strain while sitting on a toilet or in left lateral position
• Observe for concentric mucosal folds (characteristic of rectal prolapse) versus radial folds (hemorrhoids)
• Digital rectal examination to assess:
  • Anal sphincter tone (often reduced in rectal prolapse)
  • Presence of masses (to rule out rectal cancer) 2
  • Pelvic floor muscle strength

Classification

• External (complete) rectal prolapse: full-thickness protrusion beyond the anal verge
• Internal rectal prolapse: intrarectal or intra-anal intussusception not protruding externally
• Partial thickness: involving only mucosa
• Full-thickness: involving all rectal wall layers 1

Laboratory Tests

Laboratory tests are generally not required for uncomplicated rectal prolapse but may be indicated in complicated cases:

• In cases of suspected complicated rectal prolapse (incarceration, strangulation):
  • Complete blood count
  • Serum creatinine
  • Inflammatory markers (C-reactive protein, procalcitonin, lactates) 1
• These tests help assess severity and detect complications such as ischemia or perforation

Imaging Studies

Defecography

• Fluoroscopic cystocolpoproctography (CCP) is recommended for evaluation of suspected rectal prolapse, particularly for posterior compartment assessment 1
• Performed with patient in physiologic upright position on fluoroscopic commode
• Images obtained during:
  • Rest
  • Kegel (pelvic floor contraction)
  • Strain
  • Defecation
• Shows excellent correlation for internal rectal prolapse detection (88% sensitivity) 1
• Can detect clinically occult prolapse and differentiate between types of pelvic floor disorders

CT Scan

• Contrast-enhanced abdomino-pelvic CT scan is indicated in cases of irreducible or strangulated rectal prolapse to:
  • Detect associated complications
  • Assess for colorectal cancer
  • Evaluate other pelvic organ prolapse 1
• Should not delay appropriate treatment in unstable patients

MRI Defecography

• Provides better soft tissue resolution than fluoroscopic defecography
• Particularly useful for evaluating:
  • Pelvic floor muscles
  • Fascia
  • Post-surgical changes
  • Associated pelvic floor disorders 3

Additional Diagnostic Considerations

Endoscopy

• Colonoscopy or flexible sigmoidoscopy should be performed to:
  • Rule out colorectal malignancy (rectal prolapse can be associated with rectal cancer) 2
  • Identify other pathologies that may contribute to symptoms

Anorectal Manometry

• May be useful in selected cases to:
  • Assess anal sphincter function
  • Evaluate for functional disorders
  • Guide treatment decisions, especially when fecal incontinence is present 3

Diagnostic Algorithm

1. Initial Assessment:

   • Clinical history focusing on bowel habits, straining, incontinence
   • Physical examination with direct visualization during straining

2. If prolapse is visualized:

   • Determine if it's complete (external) or internal
   • Differentiate from hemorrhoids (concentric vs. radial pattern)

3. If diagnosis is uncertain or symptoms persist despite treatment:

   • Proceed to defecography (fluoroscopic or MRI)
   • Consider colonoscopy to rule out malignancy

4. For complicated cases (irreducible/strangulated):

   • Obtain laboratory tests (CBC, creatinine, inflammatory markers)
   • Consider contrast-enhanced CT scan if hemodynamically stable

Common Pitfalls and Caveats

• Misdiagnosis: Rectal prolapse is often misdiagnosed as hemorrhoids, leading to inappropriate treatment 1
• Incomplete evaluation: Failure to assess for associated pelvic floor disorders can lead to incomplete treatment
• Cancer surveillance: A sudden rectal prolapse could be the first manifestation of colorectal cancer, necessitating endoscopic examination 1
• Delayed diagnosis: Symptoms may be intermittent, requiring examination during straining to visualize the prolapse
• Pediatric cases: In children, rectal prolapse is often associated with chronic constipation and requires different management approaches 4