What is defecography?
Defecography is a radiological examination used in suspected or overt cases of obstructed constipation .
The purpose of the procedure is to identify any abnormalities of the anus and rectum, from the morphological and functional point of view.
Synonyms
Defecography is also called cinedefecografia or evacuative proctography . The examination called cystocolpography also provides for the opacification of the urinary bladder and vagina (see below).
What is obstructed constipation?
Also called dyschezia, constipation due to obstructed defecation is a particular form of constipation in which the transit of the stools is slowed down due to a rectal problem.
The most common causes include:
- morphological alterations of the rectum: rectal prolapse, rectocele, mucosal invaginations;
- functional causes: paradoxical contraction of the pubo-rectal muscle (which instead of relaxing upon defecation contracts) or other dysfunctions of the perineum.
Functional causes can be the consequence of various factors:
- poor physical activity;
- weakness of the perineum and abdominal wall muscles;
- anal hypertonus;
- habit of postponing defecation for social, psychological or because the same cause pain (anism, anal fissures, etc.);
- chronic constipation;
- chronic abuse of irritating laxatives.
Scope of Examination and Execution
Defecography is a dynamic radiological examination: thanks to X-ray beams (or to radio-magnetic fields), the doctor evaluates the way in which the patient expels from the rectum a special contrast agent introduced into the rectum with a probe.
The introduction of this contrast agent in the rectal ampoule is intended to relax the walls, causing it to be ejected which simulates natural defecation.
By observing the radiographic images the doctor is able to catch any anatomical anomalies, such as prolapses, invaginations and rectoceles.
In addition to morphological exploration, defecography allows to study the ano-rectum, and indirectly the pelvic floor, also from a functional point of view.
During the examination, the patient is seated in a special radiolucent chair, fitted under the seat with a removable container that will collect the ejected material.
The collaboration of the patient is very important, who will have to comply with the doctor's requests to contract, push and / or relax at specific times.
variants
In women, there may also be a need to evaluate the simultaneous presence of diseases affecting the bladder or vagina (cystocele, colpocele, etc.). In this case, the bladder and / or vagina must also be opaque with a different contrast agent.
If extended to the study of bladder and vagina, the examination is more correctly defined as cystocolpodecography (or perineography) .
Defecography can also include the use of a contrast agent by mouth to study the possible presence of enterocele (prolapse of the intestine). In this case the examination times are prolonged considerably, as it is necessary to wait at least an hour to allow the contrast medium to reach and distribute itself in the intestine.
After the exam
The patient can continue to emit light stools in the following days. This is due to the gradual elimination of the contrast medium injected into the rectum and eventually taken by mouth during defecography.
In the case of cystocolpodefecografia, the urine following the examination can present traces of blood; this is due to the trauma caused by the introduction of the catheter needed to inject the contrast medium into the bladder. The same catheter, although rarely, can also cause urinary infections.
Preparation
Normally, a cleaning enema is required at least three hours before the exam. In this way it is avoided that formed feces interfere with the visualization of the anorectal morphology. The hospital will provide specific instructions to the patient on how to prepare for defecography.
Before proceeding with the actual defecography, the patient may be required to sit on a radiological table for the acquisition of preliminary images in a supine position.
Precautions and Risks
Precautions
Since this is an exam that exposes to ionizing radiation, it must be avoided in cases where it is not possible to exclude an ongoing pregnancy. This problem does not arise if the more modern magnetic resonance defecography is adopted.
In general it is not necessary to interrupt any ongoing drug therapies.
risks
Defecography is a particularly safe procedure, but like all invasive tests it can be burdened with possible complications. Although rarely, contrast media can develop local inflammation. Even more rare are the cases of intestinal perforation caused by the injection of air and contrast agent; this risk becomes more concrete in the presence of chronic inflammatory conditions of the intestine, such as Crohn's disease or ulcerative colitis.
