by Gabriele Mazzetti from Pietralata
La constipation it is a symptom. It affects the doctor more than the patient because not only can it have multiple origins but it can also be difficult to decode and interpret on the basis of the story that is exposed by the person concerned. Radiology has started to contribute to the understanding of the constipation phenomenon thanks to some doctors of various disciplines of St. Mark's Hospital in London, a hospital specializing only in colon and rectal pathology.
In 1969 three researchers published the first radiological transit time technique of the colon. In 25 healthy subjects they administered polyethylene pills impregnated with barium sulfate, a known contrast medium used in radiology for various tests of the digestive system. They observed that the first radiopaque pill exceeded the colon, to put it elegantly, within the third day of taking it, and most of the markers between the third and fifth day.
The determination of the "pellets" was made by radiographing the collected feces on odorless containers. Later, John Michael Hinton and Alister Young also collaborated on the publication of studies on the effects of certain drugs on intestinal transit times using the scintigraphic techniques that were in use before their radiolabels. Young was also a pioneer of the double contrast opaque enema, also in the 50-60s.
Also at that time Lennard-Jones was an English gastroenterologist who devoted himself predominantly to the study of constipation by publishing some texts on the subject. Obviously, the scintigraphic investigations of the study of transit times have been abandoned with the diffusion of baryte radio-markers for radio-protectionist reasons. Further steps forward in this direction could derive from the use of magnetic resonance imaging; currently it is not available for the high costs of the method, therefore it is used only in defecography in selected cases.
Constipation and radiology of intestinal transit times
The first discriminating factor does not concern the diagnostic questions of the type of constipation that we want to determine, but the presence of metal objects in our body, stitches, metal prostheses made with materials incompatible with the magnetic field, pacemakers, and others. Subjects who have this type of contraindications to MRI can do conventional defecography, with X-rays and barium. Defecography assesses the dynamics of expulsion in constipation from anorectal dyskinesia, introducing barium into the rectal ampoule by means of a rectal catheter or the contents in a condom, then the patient sits on a special radiolucent stool, and is invited to carry out defecation during which the radiologist takes the x-rays and diagnoses pubo-rectal slingshot syndrome, intussusception or rectocele.
In constipation due to slowed transit of the colon, instead, the radiologist resorts to the examination of the transit time with radiopaque markers. This stage is reached after a journey that is sometimes long and fraught with obstacles, many of which are linked to psychic factors, reticence on habits in terms of evacuation, feeding, abuse of laxatives, and above all, inaccuracies and difficulties in expressing correctly the constipation disorder, or even more trivially in reporting the characteristics of the discharges to the doctor, in particular in a country like ours where the taboo of anality would perhaps discourage experimentation in the direction achieved by the authors mentioned above.
After having previously prescribed the correct dietary regimen from the point of view of fiber intake, we would have obtained the disappearance of the symptom in a large part of the patients, by applying the remainder to the test with radiopaque markers which become an objective document to be compared with the data subjective.
Experience has shown us that in half of the subjects the result of the investigation is negative, that is, the subject has the false sensation of constipation. In cases of true constipation, medical or surgical therapies will be used. The radiolabels are produced by the Sapi-Med pharmaceutical industry and distributed in some pharmacies in single-dose packs of 30 pills under the name of Time Markers. After ingesting them, two x-rays of the abdomen are made 24 and 96 hours apart. In the hospital where I exercise, the possibility of introducing this type of investigation into the gastroenterology department is being considered. We perform mainly tests of the patency of the digestive canal, administering water-soluble contrast medium by oral route following the passage of the radiopaque liquid up to the rectum in the following hours.
The most known opaque enema of the colon is rarely done, virtual colonoscopy with computed tomography is more fashionable. Experienced colleagues recommended me to do opaque enema well because the semeiotics of the colon CT is the same but double the commitment of the radiologist. Subjective motility disorders that require the advice of the gastroenterologist are delayed gastric emptying, irritable bowel and chronic constipation. Swelling and abdominal pain, low frequency of discharge and the feeling of not being able to empty the rectum lead to the general practitioner, internist or gastroenterologist, to find out if the habitual or recent constipation.
The appearance of the disorder for 2-8 months untied substantial changes in lifestyle candidates the patient to endoscopic investigation to ascertain the presence of a canalization obstacle. As a rule, habitual constipation does not lead to the doctor if it falls within the subject's daily life, it is the doctor during the visit carried out for general checks that, by writing the anamnesis, highlights this and other habits that have gone unnoticed. The simple or essential constipation, a typical expression of our modernity in which time is money and therefore there is no time even to go to the bathroom and the defecatory stimulus is suppressed when we are facing the numerous commitments of the day; on the contrary in African and Indian populations having more free time they also have more frequent faecal discharges. The other form of habitual constipation is irritable bowel syndrome which is expressed by the triad alteration of the alve, abdominal pain, dyspepsia, and is characterized by accentuation of the segmentation waves of the colon, without altering the transit times.
Among the forms with slower transit times, in addition to simple constipation, we can run into two important pathologies. The first is idiopathic slowed intestinal transit, a peculiarly female disorder in which opaque enema is normal and transit times with radio-markers are increased. The cause is not yet definitively known, insufficient relaxation of the anal sphincter and pubo-rectal muscle has been observed. On the other hand, the male gender prevails, especially in the 7th decade of life, in Ogilvie's syndrome, in which we witness severe paintings of reduced propulsive ability, occasionally released by diarrheal episodes.
In all the conditions of which we have discussed the correction of eating habits, tending to add indigestible dietary fiber, they improve hydration of the intestinal contents and create the favorable condition for faecal propulsion. The effectiveness of dietary softening of the stool is always useful both to relieve the symptom and to avoid radiological investigations. The radiological study of the transit can be prescribed after the diet test, especially when this is ineffective, and provides fundamental information with extreme procedural simplicity.