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FLUOROSCOPY
Pelvic Floor and RectumDemonstration data

Defecography

Defecography (evacuation proctography) is a dynamic fluoroscopic study of the anorectum and pelvic floor performed while the patient evacuates rectal contrast. It assesses functional disorders of defecation that are not shown by static imaging, including rectocele, rectal intussusception, enterocele and paradoxical (non-relaxing) puborectalis contraction, and helps direct surgical or pelvic floor therapy.

Indications

  • Obstructed defecation and incomplete evacuation
  • Suspected rectocele or enterocele
  • Suspected rectal intussusception or rectal prolapse
  • Suspected anismus (paradoxical puborectalis contraction / dyssynergic defecation)
  • Faecal incontinence and pelvic floor descent assessment

Contraindications & Cautions

  • Pregnancy given the gonadal radiation dose of a dynamic pelvic study
  • Inability to cooperate with the seated evacuation manoeuvres
  • Consider MR defecography as a radiation-free alternative, especially in younger patients
  • Acute anorectal pain or recent anorectal surgery limiting evacuation

Patient Preparation

  • No bowel preparation is required and may be undesirable as it alters stool consistency
  • Explain the seated evacuation and reassure the patient about privacy
  • Opacify the small bowel with oral contrast beforehand to detect enterocele if clinically indicated
  • Opacify the vagina and, where relevant, the bladder to assess global pelvic floor descent
  • Obtain consent and confirm the patient can sit and strain on the commode

Technique & Parameters

  • Instil thick barium paste of stool-like consistency into the rectum, coating the rectal wall
  • Seat the patient laterally on a radiolucent commode within the fluoroscopy field
  • Acquire lateral images at rest, on squeeze (contraction), on strain (Valsalva) and during evacuation
  • Measure the anorectal angle and pelvic floor position relative to the pubococcygeal line
  • Record the timing and completeness of evacuation and any post-evacuation intussusception
  • Add vaginal, bladder and small-bowel opacification to demonstrate multicompartment prolapse

Systematic Review

  • Measure the anorectal angle at rest, squeeze and strain
  • Assess pelvic floor descent relative to the pubococcygeal line
  • Evaluate the size and emptying of any anterior rectocele
  • Look for rectal intra-intussusception, extra-intussusception or overt prolapse during evacuation
  • Assess for enterocele or sigmoidocele descending into the rectovaginal space
  • Judge the completeness and speed of evacuation and puborectalis relaxation

Key Findings & Significance

  • Rectocele: anterior bulge of the rectal wall (commonly graded by depth) with trapping of contrast
  • Rectal intussusception: infolding of the rectal wall during evacuation, intra-rectal, intra-anal or external
  • Anismus: failure of the anorectal angle to widen and incomplete evacuation from non-relaxing puborectalis
  • Enterocele: small bowel descending into the rectovaginal septum, best seen after evacuation
  • Excessive pelvic floor descent below the pubococcygeal line on strain
  • Complete rectal prolapse with full-thickness circumferential intussusception through the anus

Differential Considerations

  • Obstructed defecation: rectocele, intussusception, anismus or descending perineum
  • Incomplete evacuation: dyssynergia versus mechanical outlet obstruction
  • Posterior vaginal bulge: rectocele versus enterocele versus sigmoidocele
  • Rectal wall infolding: physiological versus pathological intussusception
  • Global descent: multicompartment pelvic floor weakness versus isolated posterior defect

Pearls & Pitfalls

  • Enterocele is often only revealed after evacuation, so opacify small bowel and image the post-evacuation phase
  • A rectocele that empties readily is often clinically insignificant compared with one that traps contrast
  • Anismus is a functional diagnosis; correlate with symptoms and manometry as fluoroscopic findings can overlap with normality
  • MR defecography avoids ionising radiation and shows all three compartments simultaneously
  • Patient embarrassment causes underperformance; a supportive environment improves diagnostic yield

Structured Report

  • State the technique and which compartments were opacified
  • Report anorectal angle and pelvic floor descent measurements
  • Describe rectocele size and emptying, intussusception grade and any enterocele
  • Comment on puborectalis relaxation and evacuation completeness
  • Give an impression addressing the referring functional question and any surgical relevance

References

  • ACR-SAR-SCBT-MR Practice Parameter for the Performance of Fluoroscopic and MR Defecography
  • Maglinte DDT et al. Functional Imaging of the Pelvic Floor. Radiology
  • Kim NY et al. Defecography: Technique, Interpretation, and Clinical Applications. RadioGraphics
  • Royal College of Radiologists iRefer: Making the Best Use of Clinical Radiology

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.