MR defecating proctography

MR defaecography is a dynamic study for evaluation of the pelvic floor and pelvic organ prolapse.


There are four phases of evaluation:

  1. rest
  2. squeeze
  3. strain (Valsalva)
  4. defecation/evacuation

Method of evaluation

Many variations in the techniques described below exist.

Patient preparation

Typically there is no specific patient preparation required. 


Axial, coronal and sagittal T2W sequences of the pelvis are acquired to assess for structural abnormalities of the pelvic viscera and musculature. 

The dynamic study is carried out by acquiring cine images in the sagittal plane with a steady state sequence. This is similar to the sequence used for cardiac imaging. The dynamic sequences are acquired during squeezing, straining and evacuation. Prior to the evacuation sequence, 100-150 mL of ultrasound gel is instilled per rectum. Ultrasound gel is used as it is easy to acquire, manipulate into syringes, and is clearly seen on the cine sequences.


After the acquisition of the appropriate images, the following lines are drawn and measurements are taken for evaluation and assessment of the outcome of this study.

  • pubococcygeal line - a line joining the inferior aspect of the pubic symphysis to the last coccygeal joint
  • H line - corresponds to the AP diameter of the hiatus
  • M line - is the perpendicular distance between the pubococcygeal line and the posterior anorectal junction
Abnormalities to assess
Share article

Article information

rID: 42479
Tag: cases, stub
Synonyms or Alternate Spellings:
  • MR defaecography
  • Dynamic pelvic floor MRI

Support Radiopaedia and see fewer ads

Cases and figures

  • Case 1: peritoneocele
    Drag here to reorder.
  • Case 2: global pelvic floor descent
    Drag here to reorder.
  • Case 3: full thickness posterior prolapse
    Drag here to reorder.
  • Case 4: anterior rectocoele
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.