MR Defacography

Supporting Structures

Pelvic Floor Relaxation Measurnments

Anterior Compartment

Middle Compartment

Posterior Compartment

Radiographics article

Supporting Structures

Levator ani

Puborectalis and iliococcygeus
Should be convex, weak/atrophy = concave
Arcus tendineus: Pelvic sidewall attachments

Endopelvic fascial defect

Mild = Drooping mustache, prolapse of the fat in the retropubic space
Moderate= Saddlebag, drooping of the posterolateral wall(s) of the urinary bladder
Severe = Chevron, drooping of the posterolateral wall(s) of the upper third of the vagina (lose H look)

Pelvic Floor Relaxation Measurnments

Midsagittal T2-weighted MR images obtained in a female patient with normal anat-omy during rest show the reference lines most frequently used for the evaluation of pelvic floor weakness: the PCL (solid line in a) and MPL (solid line in b). Perpendicular dotted lines drawn from anatomic reference points in the anterior, middle, and posterior pelvic compartments to the PCL and MPL for the assessment of organ prolapse also are shown.

PCL (pubococcygeal line)

Inferior border of the pubic symphysis to the last coccygeal joint.

Compartment Reference Points

Anterior: PCL to bladder base.

Middle: PCL to cervix or posterosuperior vaginal apex post hysterectomy.

Posterior: PCL to anterior anorectal junction.

Normal = minimal descent (<1cm)

Normal pelvic floor anatomy in a 42-year-old female patient. Midsagittal T2-weighted MR image obtained with the patient at rest shows the PCL (solid yellow line), H line (dotted red line), and M line (dotted yellow line). The puborec-talis muscle is located just posterior to the anorectal junction, and the levator plate is parallel to the PCL.

H-Line (hiatus line)

Inferior border of the pubic symphysis to the posterior wall of the rectum at the level of the anorectal junction (superior aspect of the puborectalis muscle).

Normal:<6cm
Mild:6-8cm
Moderate:8-10cm
Severe:>10cm

M-Line:

Measures decent of the hiatus.

Vertical line drawn perpendicularly from the PCL to the posterior aspect of the H-line.

Anorectal Angle

Angle between the posterior border of the distal part of the rectum and the central axis of the anal canal.

Rest:108-127*
Defecation:+15-20*
Holding:-15-20*

Normal:<2cm
Mild:2-4cm
Moderate:4-6cm
Severe:>6cm

Levator Plate Angle

Angle between the PCL and levator plate (green line).

Normal:<10* (all the time)

Caudal inclination of the levator plate by more than 10°with respect to the PCL is an indicator of pelvic floor relaxation.

Anterior Compartment

Cystocele

Bladder base descends more than 1 cm below the PCL.

Urethral Hypermobility

Anterior angulation of the urethra by more than 30°from its resting axis on sagittal images obtained during straining or defecation.

Mild the urethra is flattened horizontally,
Moderate the urethra is horizontal,
Severe the urethra is pointed vertically

Middle Compartment

Uterine Prolapse

Anterior and inferior aspect of the cervix descends more than 1 cm below the PCL.

Vaginal Prolapse

In women who have undergone a hysterectomy, the vaginal apex should remain at least 1 cm above the PCL (*)

Peritinocele

Herniation of mesenteric fat (P) into the rectovaginal space (cul-de-sac).

Enterocele

Herniation of small intestine (arrowhead) into the rectovaginal space (cul-de-sac).

Sigmoidocele

Herniation of sigmoid colon (S) into the rectovaginal space (cul-de-sac).

Posterior Compartment

Rectocele

Outpouching measured from the expected margin of the normal anterior anorectal wall. "Rule of 2's"

Small <2cm
Medium 2-4cm
Large >4cm

Intrarectal intussusception (A)
- Minimal partial or circumferential rectal wall infolding that remains within the rectum
Intraanal intussusception (B)
- Infolding that extends into the anal canal
Extraanal intussusception or prolapse (C)
- Full-thickness invagination and eversion of the rectum, which protrudes from the anal canal

Spastic Pelvic Floor Syndrome

Constipation complaints. Paradoxical puborectal contraction/anismus

Involuntary contraction of striated pelvic floor musculature prevents the normal evacuation of feces.

Findings at conventional and MR defecography are lack of descent of the pelvic floor during defecation, prominent puborectal impression, and failure of the anorectal angle to open with resultant prolonged and incomplete evacuation.

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