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.

Defecography

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References