Defecography (also known as proctography, defecating/defecation proctography, evacuating/evacuation proctography or dynamic rectal examination) is a type of medical

radiological In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes: * ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...

imaging in which the mechanics of a patient's

defecation Defecation (or defaecation) follows digestion and is the necessary biological process by which organisms eliminate a solid, semisolid, or liquid metabolic waste, waste material known as feces (or faeces) from the digestive tract via the anus o ...

are visualized in real time using a

fluoroscope Fluoroscopy (), informally referred to as "fluoro", is an imaging technique that uses X-rays to obtain real-time moving images of the interior of an object. In its primary application of medical imaging, a fluoroscope () allows a surgeon to see t ...

. The anatomy and function of the anorectum and

pelvic floor The pelvic floor or pelvic diaphragm is an anatomical location in the human body which has an important role in urinary and anal continence, sexual function, and support of the pelvic organs. The pelvic floor includes muscles, both skeletal and ...

can be dynamically studied at various stages during defecation.

History

Defecating proctography was pioneered in 1945, during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. The procedure gained popularity at this time in the midst of an outbreak of

whipworm ''Trichuris trichiura, Trichocephalus trichiuris'' or whipworm, is a parasitic roundworm (a type of helminth) that causes trichuriasis (a type of helminthiasis which is one of the neglected tropical diseases) when it infects a human large intest ...

, which is known to cause

rectal prolapse A rectal prolapse occurs when walls of the rectum have prolapsed to such a degree that they protrude out of the anus and are visible outside the body. However, most researchers agree that there are 3 to 5 different types of rectal prolapse, depen ...

. It has since become used for diagnosis of various anorectal disorders, including

anismus Anismus or dyssynergic defecation is the failure of normal relaxation of pelvic floor muscles during attempted defecation. It can occur in both children and adults, and in both men and women (although it is more common in women). It can be caused ...

and other causes of

obstructed defecation Obstructed defecation syndrome (abbreviated as ODS, with many synonymous terms) is a major cause of functional constipation (primary constipation), of which it is considered a subtype. It is characterized by difficult and/or incomplete emptying ...

. It has fallen out of favor due to inadequate training in the technique. It is now only performed at a few institutions. Many radiology residents refer to the procedure as the "Def Proc", "Defogram", or "Stool Finale".

Indications

Defecography may be indicated for the following reasons: * Evaluation of rectal outlet obstruction (obstructed defecation) symptoms * Evaluation of all types of rectal (fecal) incontinence. * Suspected conditions such as internal rectal intussusception,

enterocele An enterocele is a herniation of a peritoneum-lined sac containing small intestine through the pelvic floor, between the rectum and the vagina (in females). Enterocele is significantly more common in females, especially after hysterectomy. It has ...

rectocele In gynecology, a rectocele ( ) or posterior vaginal wall prolapse results when the rectum bulges ( herniates) into the vagina. Two common causes of this defect are childbirth and hysterectomy. Rectocele also tends to occur with other forms of ...

sigmoidocele Sigmoidocele (also known as pouch of Douglas descent) is a medical condition in which a herniation of peritoneum containing loops of redundant sigmoid colon descends (prolapses) into the rectouterine pouch (in females), between the rectum and the v ...

. * To compare pre- and post-surgical repair of rectal outlet obstruction (obstructed defecation). Specifically, defecography can differentiate between anterior and posterior

. Also, in external

that was not directly visualized during examination, this radiographic projection will demonstrate its presence.

Technique

In females, pre-procedural preparation involves smearing a small amount of

barium Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. Th ...

contrast agent A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radiop ...

in the vagina, which will help to identify if anterior

is present. The technique itself involves the insertion of a

caulking gun Caulk (also known as caulking and calking) is a material used to Seal (mechanical), seal Joint (building), joints or seams against leakage in various structures and piping. The oldest form of caulk consisted of fibrous materials driven into ...

device into the rectum with a subsequent manual infusion of barium paste until there is adequate distension. The patient is then transferred to a portable plastic commode which is situated next to a fluoroscope which records the defecation. Positioning of the X-ray camera is of paramount importance as visualization of the buttocks, rectal vault, and lower pelvis is critical.

Diagnostic yield and interpretation

Anatomical and physiological parameters that can be objectively measured by this investigation include: * Anorectal angle: This is the "mid-axial longitudinal axis of the rectum and the anal canal", created by the anterior pull of the puborectalis sling at the level of the anorectal junction. At rest, it is held at 90 - 100°. This becomes more acute (70 - 90°) when the patient contracts the anal sphincters and pelvic floor muscles, and more obtuse (110 - 180°)during defecation. * Perineal descent: This is "the caudad movement of the pelvic floor uringstraining". Defecation normally involves a relaxation of the pelvic floor (

levator ani The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis. It is attached to the inner surface of each side of the ...

), leading to descent of the perineum. After straining, the opposite occurs, the perineum rises. From the proctogram, descent is calculated by drawing an imaginary line (the pubococcygeal line) between the most inferior point on the

pubic bone In vertebrates, the pubis or pubic bone () forms the lower and anterior part of each side of the hip bone. The pubis is the most forward-facing (ventral and anterior) of the three bones that make up the hip bone. The left and right pubic bones ar ...

and the tip of the

coccyx The coccyx (: coccyges or coccyxes), commonly referred to as the tailbone, is the final segment of the vertebral column in all apes, and analogous structures in certain other mammals such as horse anatomy, horses. In tailless primates (e.g. hum ...

. Normal perineal descent or elevation is less than 4 cm from the pubococcygeal line in either direction (

superior Superior may refer to: *Superior (hierarchy), something which is higher in a hierarchical structure of any kind Places * Superior (proposed U.S. state), an unsuccessful proposal for the Upper Peninsula of Michigan to form a separate state *Lak ...

or inferior). * Efficiency of emptying/evacuation: Normally, there is 90-100% evacuation of rectal contents. *

Anal canal The anal canal is the part that connects the rectum to the anus, located below the level of the pelvic diaphragm. It is located within the anal triangle of the perineum, between the right and left ischioanal fossa. As the final functional s ...

length: This is measured during maximal evacuation. * Anal canal width: Again measured during maximal evacuation, this is usually less than 2.5 cm. Conditions which may be demonstrated include: *

Anismus Anismus or dyssynergic defecation is the failure of normal relaxation of pelvic floor muscles during attempted defecation. It can occur in both children and adults, and in both men and women (although it is more common in women). It can be caused ...

(pelvic floor dyssynergia): It has been suggested that some patients may be embarrassed by this procedure, which give findings of abnormal defecation. For example, the patient may not be able to relax under the conditions, leading to relaxation failure of puborectalis and false positive diagnosis of

. It has also been reported that there is a high false positive rate of anismus diagnosis with

anorectal manometry Anorectal manometry (ARM) is a medical test used to measure pressures in the anus and rectum and to assess their function. The test is performed by inserting a catheter, that contains a probe embedded with pressure sensors, through the anus and in ...

for similar reasons. *

Rectocele In gynecology, a rectocele ( ) or posterior vaginal wall prolapse results when the rectum bulges ( herniates) into the vagina. Two common causes of this defect are childbirth and hysterectomy. Rectocele also tends to occur with other forms of ...

: This is the most common finding with this type of imaging. Almost always, this is an anterior rectocele where the anterior rectal wall bulges forward, into the vagina in females. In males, the prostate gland gives more support in this area compared to the vaginal cavity, so rectoceles, especially anterior rectoceles are uncommon in males. Less commonly and in males, there may be posterior rectoceles, where the rectum bulges posteriorly. Both the size and the efficiency of emptying can be assessed with proctography. Since many rectoceles are asymptomatic, this may only be a significant finding if there are symptoms of

. Usually rectoceles greater than 3 cm and those that do not empty are clinically significant. *

Enterocele An enterocele is a herniation of a peritoneum-lined sac containing small intestine through the pelvic floor, between the rectum and the vagina (in females). Enterocele is significantly more common in females, especially after hysterectomy. It has ...

and

: Enterocele is a prolapse of peritoneum that contains a section of

small intestine The small intestine or small bowel is an organ (anatomy), organ in the human gastrointestinal tract, gastrointestinal tract where most of the #Absorption, absorption of nutrients from food takes place. It lies between the stomach and large intes ...

. Sigmoidocele is a prolapse of peritoneum that contains a section of

sigmoid colon The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus ''s ...

. In females, these prolapses usually descend between the rectum and the vagina. They are most likely to be seen during straining. *

Rectal prolapse A rectal prolapse occurs when walls of the rectum have prolapsed to such a degree that they protrude out of the anus and are visible outside the body. However, most researchers agree that there are 3 to 5 different types of rectal prolapse, depen ...

/ Internal rectal intussusception: The rectum may be seen to prolapse, whether internally or externally. There can be difficulty differentiating between internal intussusception and a normal rectal fold. The thickness of the intussusception is half the width of the intussusception (the intussusception is a doubled over layer of rectal wall). This is most likely to be seen during straining. * Megarectum: This is excessive width (>9 cm) of the rectum at the level of the distal sacrum and incomplete evacuation. * Descending perineum syndrome: If the perineum descends >4 cm, descending perineum syndrome may be diagnosed. *

Fecal incontinence Fecal incontinence (FI), or in some forms, encopresis, is a lack of control over defecation, leading to involuntary loss of bowel contents—including flatus (gas), liquid stool elements and mucus, or solid feces. FI is a sign or a symptom ...

: If the barium paste does not stay in the rectum.

Cinedefecography and MRI defecography

Cinedefecography is a technique that is an evolution of defecography. The defecation cycle is recorded as a continuous series rather than individual still radiographs. More recent techniques involve the use of advanced, cross-sectional imaging modalities such as

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...

.MRI Defecating Proctogram
/ref> This is known as dynamic pelvic MRI, or MRI proctography. The MRI proctography also called MRI defecography is not as efficient as conventional X-ray defecography for some problems.

References

External links

Dynamic rectal examination on "the Radiology Assistant"
many example defecating proctograms with interpretation. {{Digestive system procedures Diagnostic obstetrics and gynaecology Digestive system imaging Fluoroscopy Colorectal surgery