Examination and diseases of the small bowel

Contrary to the upper GI tract and the colon the small bowel could not be visualized with endoscopy. Thus its radiographic examination requires a different approach.

Material and methods:

Studies can be either morphological or functional. For assessment of the morphology selective enterography is the most suitable method. Functional studies are called follow through or passage examinations.

Examination technique:

Nowadays, selective enterocylsis is performed with CT or MRI scanning. With the more detailed imaging technique not only the parietal morphology of the small intestine, but lesions in the surrounding abdominal structures can be simultaneously detected.

Capsule endoscopy is a novel method, when the patient swallows a plastic capsule equipped with a miniature camera, which takes serial pictures of the intestinal wall as it moves forward.

It exits the anus by the natural bowel movements, thus pictures taken by the capsule can be analyzed.

Follow through studies are performed when there is clinical suspicion of a mechanical bowel obstruction, also called as ileus. After an initial plain abdominal film has been taken the patient consumes water soluble contrast which passes through the intestinal tract. Meanwhile, additional abdominal radiographs are taken with one hour intervals. These are the so called

―hpc‖ radiographs. If a mechanical obstruction is suspected the examination is continued until the contrast agent gets to the rectum. The follow through study can differentiate whether the patient has ileus or partial block of the intestinal transit, also called subileus.

The original meaning of the term ―ileus‖: A word of Greek origin, it was initially used to describe only intestinal twisting or volvulus. Nowadays, it is used in a more general sense to all kinds of mechanical or functional blockage of the intestinal contents.

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Fig.20.: Follow-through examination

On the abdominal radiograph distension of the small bowel loops and air-fluid levels can be identified. It is important to describe forwarding of the contrast media by time or if

mechanical obstruction is seen. Morphology of the intestinal loops could not be assessed with this method. This study is specifically conducted to examine the transit function only.

Fig.21.: Radiograph of selective enterocylsis

Chron’s disease

Clinical presentation: diarrhea, weight loss.

Fig.22. Crohn’s disease

Radiographic findings: Most frequently luminal narrowing of the terminal ileum is detected.

The wall is thickened, intramural and inter-intestinal fistulas may develop. The abdominal plain film is not suitable for identification of abdominal abscesses.

Diverticula can form in the small bowel, but with a very low frequency. In addition to regular diverticula rarely a Meckel diverticulum is seen.

167 13.7. Examination and diseases of the colon

13.7.1. Radiographic examination of the colon, material and methods:

 single-contrast (irrigoscopy)

 double-contrast (colonography, barium enema)

 virtual colonoscopy

The barium sulfate suspension forms positive contrast while air is the negative contrast.

Irrigoscopy is a method to examine the large bowel which requires a careful preparation. Only the fully cleansed colon can be imagined properly:

Preparation:

On the night before the examination the large bowel should be cleared. Nowadays, we try to avoid enema preparations. For endoscopy preparation a clear-liquid diet is recommended which is best achieved by consuming mixed electrolyte rich fluids. Some preparations are specifically formulated for this purpose such as the X-prep.

Single-contrast acute irrigoscopy examination with water-soluble contrast medium:

Indication:

 large bowel ileus

 suspected perforation

 suspected enteral fistula 13.7.2. Diseases of the colon Colon diverticulosis:

One of the most common disorder of the large intestine, its frequency increases by age.

Clinical presentations: Patients can be symptom fee. If complicated with diverticulitis it can cause abdominal pain in the region corresponding to the affected bowel segment. Bleeding, perforation can occur.

Radiographic findings: multiplex round collections are seen on the sigmoid and descending colon. Double-contrast irrigoscopy.

Fig.23.: Radiographic image: multiple, round filling defects are seen on the sigma and on the descending colon.

Fig.24.: Double-contrast irrigoscopy

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Colorectal polyp

Clinical presentation: Usually colon polyps are asymptomatic and constitute an accidental finding. They can bleed, thus a positive fecal blood test can draw attention to their existence.

They are also considered precancerous lesions. Polyps larger than 2 cm are potentially malignant.

Fig.25.: Radiographic findings: A round lesion with sharp edges protrudes into the intestinal lumen.

Morphologic types:

 sessile poly

 polyp like with stalk

 villous adenomas Colorectal tumors

Most commonly they are detected on the sigmoid colon however; all segments of the colon can be affected with variable frequency. Tumors in the right half of the colon bleed more frequently while, tumors in the left half show grater tendency for stenosis.

Clinical presentation:

Abdominal fullness, constipation, and with time diarrhea is characteristic, with complete obstruction of the lumen no stool is passed and ultimately colonic ileus ensues.

Fig.26.: Napkin ring sign (or apple core sign), is a typical presentation of colon tumors.

Fig.27. Rectal cancer arising from a villous adenoma causes a rugged contour and an extensive filling defect.

169 13.8. Concluding message

The purpose of this chapter is to aid the preparation of medical students. The author’s primary intention was to specifically emphasize and to help the students to master the proper

radiographic terminology. Thus, when reading a radiology report they can associate the findings with a radiographic image, and can understand the types of alterations described by the radiologist. The consultation between the clinician and the radiologist could only reach completeness, and can benefit the patient the most, if they are mutually familiar with the terminology of the each other’s fields of specialty.

Translated by Pál Kaposi Novák

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