GI/GU 2: RSNA Defecography

Deciphering the Defecogram: A Comprehensive Review of Fluoroscopic Defecography Nathan Kim MD Perry Pickhardt MD David Kim MD Jessica Robbins MD

Learning Objectives  Understand the role of defecography in the evaluation of functional

anorectal disorders  Discuss the limitations of fluoroscopic defecography  Identify normal structural anatomy and anorectal function  Recognize the full spectrum of pathology in the pelvic floor and

anorectum

Introduction • Defecography, also known as evacuation proctography, is a

fluoroscopic examination that enables functional, real-time assessment of the mechanics of defecation in a physiologic setting • Allows for evaluation of morphology of rectum and anal canal • Common Indications include: • Chronic constipation • Incomplete or obstructed evacuation • Fecal incontinence • Mucous or bloody discharge • Perineal pain or discomfort • Follow-up for patients who have undergone surgery in the pelvic region

Technique  Patient is prepared with contrast  Barium is administered orally one hour prior to exam to opacify the small bowel  40-60 mL of thick barium is instilled into the vagina  60 mL of thin barium and up to 180 mL of thick barium is instilled into the rectum  Patient is placed on the fluoroscopic

commode • Position the image to include the skin of the perineum, the coccyx and pubic bones in the field of view

Technique • Multiple cine clips are obtained

during full cycles of: • Squeeze • Valsalva • Defecation • If the patient identifies any maneuvers that assist with defecation, then a cine clip should be repeated with the patient performing the maneuvers

Anatomy • The puborectalis attaches

anteriorly to the pubic symphysis and wraps posteriorly around the anorectal junction • The puborectalis, iliococcygeus, and pubococcygeus form the levator ani and the muscular pelvic floor • Together, the levator ani and anal sphincters provide normal fecal continence

Anatomy • The puborectalis forms a sling

around the anorectal junction • The internal and external sphincters encompass the anus

Anatomy • Rectum measures approximately 12-

15 cm in length and extends from the rectosigmoid junction to the level of the puborectalis and anorectal junction • Anal canal measures approximately 4 cm and extends from the puborectalis to the anal verge • Rectum is anchored in the pelvis by the pelvic floor, the levator ani complex

12-15 cm

4 cm

Anatomy • The impression of the puborectalis

forms the anorectal angle • At rest, the anorectal angle is roughly 90° • The anal canal is closed by the internal and external anal sphincters • All pelvic structures are above the pelvic floor denoted by the pubococcygeal line, a line connecting last coccygeal joint with the inferior margin of pubis

REST

Anatomy

• During the squeeze phase,

the puborectalis contracts elevating and anteriorly displacing the anorectal angle

SQUEEZE

Anatomy

• During Valsalva, the

puborectalis relaxes, returning to anorectal angle to baseline (90°) • The pelvic structures remain above the pubococcygeal line • Throughout all phases, the vagina (V) remains closely apposed to the rectum and the small bowel (S) remains in the peritoneum

VALSALVA

S V

Anatomy

• During defecation the anal

sphincters relax, allowing the anal canal to open and allow full passage of contrast • With defecation, the anorectal angle becomes obtuse and the rectum descends

DEFECATION

Pelvic Floor Pathology Overview  Rectocele  Descending Perineum Syndrome  Pelvic Floor Dyssynergy  Enterocele/Sigmoidocele  Rectal Intussusception  Rectal Prolapse

Rectocele

• Protrusion of anterior rectal wall due to weakness in the

rectovaginal septum • Most often caused by obstetric injury; can be seen in nulliparous

patients • Nonspecific presentation including pelvic pain, constant pressure,

backache, and constipation • Can be seen in 80% of healthy volunteers • Generally symptomatic when >2cm in size • Size as predicted at defecography does not predict the outcome of

rectocele repair

Rectocele

• Rectocele (*) protrudes

anterior from the expected contour of the rectum (dashed line)

*

• Small bowel (*) remains

within the peritoneal cavity • Rectocele indents upon the

posterior wall of the vagina (*)

* *

Descending Perineum Syndrome

• Result of pelvic floor hypotonia • Presents with rectal prolapse, incontinence, obstructed

evacuation or rectal pain • Descent of the anorectal junction by > 3-3.5 cm or anorectal junction > 3 cm below its normal position at rest • Treatment options include conservative measures such as suppositories and biofeedback

Descending Perineum Syndrome

• During evacuation, the

rectum (*) descends below the pubococcygeal line (dashed line) a sign of pelvic floor laxity

*

• Small bowel (*) remains

within the peritoneal cavity

*

Pelvic Floor Dyssenergy

• Also known as nonrelaxing puborectalis syndrome, spastic pelvic • • • • •

floor syndrome, puborectalis dyskinesia or anismus Often presents with symptoms of obstructed evacuation such as straining and tenesemus Manifests as persistent indentation of the puborectalis sling, failure to increase the anorectal angle, and incomplete emptying Diagnosed in conjunction with anorectal manometry and electromyography Treated with diet and exercise, timed toilet training, and biofeedback therapy No established surgical therapy at this time

Pelvic Floor Dyssenergy

 There is persistent contrast

within rectum (*) after repeated evacuation attempts. During straining, the indentation of the puborectalis (arrow) remains and the anorectal angle fails to become more obtuse.

*

Enterocele • Herniation of the small bowel into the rectovaginal space • Presents as pelvic pain, heaviness on standing, incomplete

evacuation, & postevacuation discomfort • Often associated with vaginal vault prolapse • Managed with conservative treatment with biodfeedback and

regulating defecation • Surgical repair generally reserved for patients with intractable

pelvic pain • Surgical options include transabdominal, transvaginal or

laparoscopic approaches to obliterating pouch of Douglas

Enterocele  Small bowel (*) herniates

into the rectovaginal space, exerting mass effect upon both the rectum (*) posteriorly and vagina (*) anteriorly  A small rectocele (arrow) is also seen

** * *

Rectal Intussusception • Concentric invagination of the bowel wall during defecation

or straining

• May remain within the rectum (intrarectal intussusception),

anus (intra-anal intussusception) or extend pass the anal canal (rectal prolapse)

• Associated with solitary rectal ulcer syndrome (seen in 45-

80% of patients)

• May be come apparent only during the late phases of

defecation.

Rectal Intussusception  (A) During early phase of

defecation, only a small rectocele is visualized (*).  (B) During the final phase

of defecation, the proximal rectum (*) intussuscepts into the distal rectum (arrow).

* A

* B

Rectal Intussusception  (C) During late defecation

phase of another patient, in addition to a rectal intussusception (*), the small bowel (*) intussuscepts into the rectum

* * C

Rectal Prolapse • Protrusion of all layers of the rectal wall through the anal

canal • Presents with constipation, fecal incontinence, abdominal

discomfort, incomplete evacuation, and pelvic organ prolapse • Defecography can reveal other abnormalities including pelvic

organ collapse, which would require more complex operations • Managed with surgical repair via abdominal or perineal

approach

Rectal Prolapse  (A) Rectum protrudes

through the anal canal (arrows). Tiny amount of residual contrast is visualized in the proximal rectum (*).

* A

Rectal Prolapse  (B) Large rectal prolapse

(arrows) containing a large enterocele (*) and the apex of the vagina (arrow).

Residual contrast remains within the proximal rectum (*).

*

B

*

Rectal Prolapse  (C) At rest, the anorectal

junction (arrow) sits below the pubococcygeal line (dashed line) and there is an enterocele (*).

*

 With evacuation, there is

rectal prolapse and the enterocele intussuscepts into the prolapsed rectum.

C

Limitations  Artificial and potentially embarrassing environment  No standard of reference  Poor inter-observer reliability  Poor correlation with patient symptoms  Ionizing radiation  Ultimately management decisions should not rely solely on

imaging and should incorporate physical examination and physiologic testing

Management Options  Transabdominal Rectoplexy  affix the pararectal tissue to the sacral promontory using suture or mesh  favored over perineal approach due to lower recurrence rates  can be done with or without sigmoid resection  Perineal Approach  traditional option for poor surgical candidates although now less common with development of laparoscopic approaches  Altemeier procedure  Delorme procedure

Summary • Defecography is a widely available method for the

anatomic and functional assessment of defecation disorders • Limited by lack of established criteria and lack of interobserver reliability • Serves as a complement to physical exam and physiologic testing, particularly for rectal intussusception and enterocele, which can be difficult to detect on other exams

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