Dietary fibers in the preparation of the bowel for diagnostic barium enema

Wheat Fibre before Radiography of the Large Bowel

Constipation is today treated by adding non-absorbable fibres to a normal diet. The aim of this investigation was to study the influence of fibres on colon cleansing results in patients referred for double contrast examination of the colon. A series of 240 consecutive patients were separated into two groups, one treated with one day of starvation and the routine cleansing regimen, the other group with wheat fibres thrice daily for four days before the day of the regular cleansing program. No difference in cleanness between the two groups was seen.

Bowel preparation for CT colonography

Bowel preparation represents an essential part of CT colonography, as the accuracy of the exam is strongly related to the adequacy of colonic cleansing, and a poor bowel preparation may compromise the diagnostic quality even despite optimization of all other acquisition parameters. Residual stool and fluid in the large bowel may affect the interpretation of the exam and may increase the number of false positives and false negatives. In this regard, the majority of patients having undergone CT colonography state that bowel preparation is the most unpleasant part. Unfortunately, to date no definite consensus has been reached about the ideal bowel preparation technique, and there is great variability in preparation strategies across diagnostic centers. The purpose of this review article is to describe the development and evolution of bowel preparation techniques in order to choose the best approach for optimizing the diagnostic quality of CT colonography in each patient.

Low-fiber diet in limited bowel preparation for CT colonography: Influence on image quality and patient acceptance

OBJECTIVE

The purpose of this study was to determine whether a low-fiber diet is necessary for optimal tagging-only bowel preparation for CT colonography.

SUBJECTS AND METHODS

Fifty consecutively enrolled patients received an iodine bowel preparation: 25 patients used a low-fiber diet and 25 used no special diet. One observer determined the tagging quality per segment on a 5-point scale (1, inhomogeneous tagging; 5, excellent preparation) and the largest size of untagged feces. Semiautomatic measurements of density and homogeneity of residual feces were performed. Patient acceptance was assessed with questionnaires. Per polyp sensitivity for polyps 6 mm in diameter and larger was calculated for two experienced observers.

RESULTS

Tagging quality was scored less than grade 5 in 15 segments (10%) in the low-fiber diet group and in 25 segments (17%) in the unrestricted diet group (p = 0.098). One piece of untagged feces 10 mm in diameter or larger was found in the low-fiber diet group, and 12 were found in the unrestricted diet group (p < 0.001). Automatic measurement of attenuation resulted in a mean value of 594 HU in the low-fiber diet group and 630 HU in the unrestricted diet group (p = 0.297). In the low-fiber diet group, 22% of patients indicated that the bowel preparation was extremely or severely burdensome; 8% of patients in the unrestricted diet group had this response (p = 0.19). Thirty-two polyps 6 mm in diameter or larger were found in the low-fiber diet group and 30 in the unrestricted diet group. Observer 1 had 84% and 77% sensitivity in detecting polyps 6 mm in diameter or larger in the low-fiber diet and unrestricted diet groups, respectively (p = 0.443), and observer 2 had 97% and 83% sensitivity (p = 0.099).

CONCLUSION

Use of a low-fiber diet in bowel preparation for CT colonography results in significantly less untagged feces and shows a trend toward better residue homogeneity.

Double-contrast barium enema examination technique

This review article presents the principles for performing a safe, comfortable, and accurate double-contrast barium enema examination. The procedure is a flexible examination in which the fluoroscopist interacts with the patient, the controls of the fluoroscope, and the image on the television monitor. During a double-contrast examination, images of the colon are created by manipulating the patient, the barium pool, and the amount of air insufflated into the rectum. Fluoroscopy is essential for guiding the radiologist to obtain spot images with adequate technical factors. The fluoroscopist analyzes the luminal contour, the barium-coated mucosal surface en face, and the barium pool to detect abnormalities in the colon. With careful technique, a high-quality examination can be performed in most patients.

Barium enema preparation: a study of low-residue diet, "Picolax' and 'Kleen-Prep'

A prospective, randomized three-arm trial is presented of 150 consecutive patients attending for double-contrast barium enema (BE). This compares 'Picolax' (a combined stimulant and osmotic agent), 'Picolax' following a 3 day low-residue diet and 'Kleen-Prep' (a polyethylene-glycol osmotic agent). Faecal clearance, mucosal coating and colon fluid were scored in four colonic segments by two radiologists working independently and blinded to the preparation used. Analyses of an elderly subgroup and of side effects was performed. Low-residue diet conferred no benefit to Picolax preparation, which was satisfactory (ability to exclude 5 mm polyps) in 80% of patients. Kleen-Prep failed to achieve adequate preparation in 46%, due to excess fluid and poor mucosal coating. Kleen-Prep caused more patient nausea, abdominal bloating and pain than Picolax. Patients 70 years and older had similar results. Low-residue diet need not be used in addition to Picolax. Kleen-Prep as a single agent is not recommended for BE preparation.

A blinded prospective trial of low-residue versus normal diet in preparation for barium enema

This study was undertaken to determine whether the omission of a low-residue diet in the days leading up to barium enema resulted in poorer bowel preparation. 300 patients were randomized prospectively into one of two groups. One group followed a low-residue diet for the 3 days leading up to the study, the other continued their usual diet. Both groups had two doses of "Picolax" the day before the study. 17 patients did not attend, and a further two patients were excluded, leaving 281 patients for prospective study. The subsequent investigation was assessed blind by a consultant radiologist and graded for faecal residue, mucosal coating and diagnostic quality. No statistically significant difference was found between the two groups for amount of faecal residue (p < 0.25), mucosal coating (p < 0.25) or diagnostic quality (p < 0.5). We conclude, therefore, that a preliminary low-residue diet is unnecessary in the preparation of patients for barium enema. Patients should continue with their usual diet up to the day prior to the test and then have standard purgative preparation.