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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