Error Count of Radiopaque Markers in Colonic Segmental Transit Time Study

Radiopaque marker colonic transit study in the pediatric population BSPGHAN Motility Working Group consensus statement

Functional constipation (FC) is a common condition in childhood in the United Kingdom and worldwide. Various radiological approaches have been established for diagnostic purposes. The radiopaque marker study (ROMS) is universally accepted and used to assess colonic transit time (CTT) in children with FC. Despite being widely used, there is a lack of standardization with various technical protocols, reproducibility of different populations, the purpose for using investigation, variance in the number of markers used, the amount of study days and calculations, the need to empty the colon before performing the test, and whether to perform on medication or off, or the use of specific diets. As part of the British Society of Paediatric Gastroenterology, Hepatology and Nutrition (BSPGHAN) motility working group (MWG), we decided to explore further into the evidence, in order to provide guidance regarding the use of ROMS in dealing with FC in the pediatric population.

Bowel transit studies in children: evidence base, role and practicalities

Constipation is common in children and adults with varied worldwide prevalence. The majority of children have functional constipation as defined by Rome clinical criteria and respond favourably to standard medical therapy; up to one-third can develop difficult-to-treat constipation requiring investigation and specialist treatment. Colon function tests aim to assess the neuromuscular integrity, the movement of faeces across the colon and evaluate/predict response to the therapy. The 'ideal' test should be practical, non-invasive, widely available and cost-effective. None of the available diagnostic tools is designed to provide a comprehensive assessment of colon function and clinicians often have to combine more than one test to answer different questions. In this review, we aim to assess the strengths and limitations of the commonly available diagnostic investigations (radiopaque marker studies, scintigraphy, wireless motility capsule and colonic manometry) used to assess colon transit in children and to provide guidance on the most appropriate test for particular clinical settings.

Constipation screening in people taking clozapine: A diagnostic accuracy study

OBJECTIVE

Clozapine is the favoured antipsychotic for treatment-refractory schizophrenia but its safe use requires careful adverse-effect management. Clozapine-induced gastrointestinal hypomotility (CIGH or 'slow-gut') is one of the most common and serious of clozapine's adverse effects. CIGH can lead to paralytic ileus, bowel obstruction, gastrointestinal ischaemia, toxic megacolon, and death. Enquiring about constipation is a simple and commonly used screening method for CIGH but its diagnostic accuracy has not previously been assessed.

METHODS

First, we examined the reliability of asking about constipation compared with asking about Rome constipation criteria in inpatients treated with clozapine (n = 69). Second, we examined the diagnostic accuracy of (1) self-reported constipation and (2) the Rome criteria, compared with the reference standard of gastrointestinal motility studies.

RESULTS

After 30 motility tests, it was clear constipation screening had very poor diagnostic properties in this inpatient group and the study was terminated. Although 73% of participants had objective CIGH on motility testing, only 26% of participants self-reported constipation, with sensitivity of 18% (95% CI: 5-40%). Specificity and positive predictive values were higher (95% CI: 63-100% and 40-100%, respectively). Adding in Rome criteria improved sensitivity to 50% (95% CI: 28.2-71.8%), but half the cases were still missed, making this no more accurate than tossing a coin.

CONCLUSIONS

CIGH is often silent, with self-reported constipation having low sensitivity in its diagnosis. Treating CIGH based on self-reported symptoms questions will miss most cases. However, universal bowel motility studies are impractical. In the interests of patient safety, prophylactic laxatives are suggested for people taking clozapine.

The Porirua Protocol in the Treatment of Clozapine-Induced Gastrointestinal Hypomotility and Constipation: A Pre- and Post-Treatment Study

BACKGROUND

Clozapine, an antipsychotic used in treatment-resistant schizophrenia, causes slow gastrointestinal transit in 50-80% of patients. Clozapine-induced gastrointestinal hypomotility is both common and serious, and potential complications include severe constipation, ileus, bowel obstruction and related complications, with a higher mortality rate than clozapine-related agranulocytosis. Little evidence exists on its prevention and management.

METHOD

Using a well-validated radiopaque marker ('Metcalf') method, we compared colonic transit times (CTTs) of clozapine-treated inpatients not receiving laxatives with their transit times when receiving laxatives, with treatment prescribed according to the Porirua Protocol for clozapine-related constipation (docusate and senna augmented by macrogol 3350 in treatment-resistant cases).

RESULTS

The median age of participants was 35 years, and median clozapine dose, plasma level and duration of treatment were 575 mg/day, 506 ng/mL and 2.5 years, respectively. Overall, 14 participants (10 male) were enrolled and all completed the study. Transit times improved markedly with laxative treatment. Median colonic transit without laxatives was 110 h (95% confidence interval [CI] 76-144 h), over four times longer than normative values (p < 0.0001). Median CTT with laxatives was 62 h (95% CI 27-96 h), a 2-day reduction in average transit time (p = 0.009). The prevalence of gastrointestinal hypomotility decreased from 86% pre-treatment to 50% post-treatment (p = 0.061). Severe gastrointestinal hypomotility decreased from 64 to 21% (p = 0.031). Subjective reporting of constipation did not correlate well with objective hypomotility, and did not change significantly with treatment.

CONCLUSION

Treating clozapine-treated patients with docusate and senna augmented by macrogol appears effective in reducing CTTs in clozapine-induced constipation. Randomised controlled trials are the next step. Australian New Zealand Clinical Trial Registry ACTRN12616001405404 (registered retrospectively).

Effect of Food Status on the Gastrointestinal Transit of Amphotericin B-Containing Solid Lipid Nanoparticles in Rats

Amphotericin B (AmB) is poorly absorbed from the gastrointestinal tract. Recent studies have suggested enhanced drug absorption from solid lipid nanoparticles (SLN). Little is known of the fate of AmB absorption within the gastrointestinal tract, and no gastrointestinal transit study has yet been performed on AmB-containing nano-formulations. We aimed to investigate the effect of food on the gastrointestinal transit properties of an AmB-containing SLN in rats. Three SLNs containing AmB, paracetamol, or sulfasalazine were formulated using cocoa butter and beeswax as lipid matrices and simultaneously administered orally to Sprague-Dawley rats. Paracetamol and sulfapyridine were used as marker drugs for estimating gastric emptying and cecal arrival, respectively. The pharmacokinetic data generated for paracetamol and sulfapyridine were used in estimating the absorption of the AmB SLNs in the small and large intestines, respectively. A delayed rate of AmB absorption was observed in the fed state; however, the extent of absorption was not affected by food. Specifically, the percentages of AmB absorption during the fasted state in the stomach, small intestine, and colon were not significantly different from absorption within the respective regions in the fed state. In both states, however, absorption was highest in the colon and appeared to be a combination of absorption from the small intestine plus absorption proper within the colon. The study suggests that AmB SLN, irrespective of food status, is slowly but predominantly taken up by the lymph, making the small intestine the most favorable site for the delivery of the AmB SLNs.

Clozapine-treated Patients Have Marked Gastrointestinal Hypomotility, the Probable Basis of Life-threatening Gastrointestinal Complications: A Cross Sectional Study

BACKGROUND

Gastrointestinal side effects are particularly common with clozapine and occur with other antipsychotics, ranging from mild constipation to fatal bowel obstruction and/or ischemia. While this adverse-effect spectrum has been attributed to 'gastrointestinal hypomotility', gastrointestinal transit times in antipsychotic-treated patients have not previously been measured, making this mechanism speculative.

METHODS

Using standardized radiopaque marker ('Metcalf') methods we established colonic transit times of antipsychotic-treated psychiatric inpatients and compared them with population normative values. We analyzed results by antipsychotic type, antipsychotic dose equivalent, anticholinergic load, duration of treatment, gender, ethnicity, and age.

OUTCOMES

For patients not prescribed clozapine, median colonic transit time was 23 h. For patients prescribed clozapine, median transit time was 104.5 h, over four times longer than those on other antipsychotics or normative values (p < 0.0001). Eighty percent of clozapine-treated patients had colonic hypomotility, compared with none of those prescribed other antipsychotics (olanzapine, risperidone, paliperidone aripiprazole, zuclopenthixol or haloperidol). In the clozapine group, right colon, left colon and rectosigmoid transit times were all markedly abnormal suggesting pan-colonic pathology. Hypomotility occurred irrespective of gender, age, ethnicity, or length of clozapine treatment. Transit times were positively correlated with clozapine plasma level (rho = 0.451, p = 0.045), but not with duration of treatment, total antipsychotic load or demographic factors.

INTERPRETATION

Clozapine, unlike the other antipsychotics examined, causes marked gastrointestinal hypomotility, as previously hypothesized. Pre-emptive laxative treatment is recommended when starting clozapine.

Defaecography and colonic transit time for the evaluation of female patients with obstructed defaecation

PURPOSE

Colonic transit time and defaecography are well known, commonly used studies for evaluating patients with chronic constipation. The aim of this study was to compare colonic transit time with radiopaque markers and defaecography in female patients with obstructed defaecation.

MATERIALS AND METHODS

In a prospective observational study, between January 2010 and December 2012, a total of 30 female patients, mean age 60 years, with symptoms of obstructed defaecation were subjected to colonic transit time and defaecography, and divided into two groups: normal or abnormal colon transit time. The results were statistically compared using the Chi-square test.

RESULTS

The comparison of data between colonic transit time and defaecography showed the following groups: group 1 (6/30 = 20 %) with normal colonic transit time but abnormal defaecography, and group 2 (24/30 = 80 %) with abnormal colonic transit time; the latter was further divided into two subgroups: group 2a (4/24 = 17 %), patients with inertia coli; group 2b (20/24 = 83 %), patients with impaired defaecation demonstrated at defaecography. There was a significant statistical difference between the radiological findings in these groups.

CONCLUSIONS

This study confirmed the value of both defaecography and colonic transit time in assessing clinically obstructed women. Obstructed defaecation might not always be associated with abnormal colonic transit time. Likewise, not all constipated patients had signs of obstructed defaecation. The differential diagnosis between colonic slow transit constipation and constipation due to pelvic floor disorders is essential for an adequate strategy of care.

Measurement of colonic transit time based on radio opaque markers in patients with chronic idiopathic constipation; a cross-sectional study

Background:

Constipation is one of the most common gastrointestinal disorders particularly in industrialized countries. Incidence of constipation varies from 3.4 % to 27.2% in different societies. Increase in urban population, industrialization of communities, changes in behavioral and nutritional habits and inactivity have increased the number of patients suffering from constipation.

Objectives:

The aim of the study was to measure colonic transit time in patients with chronic idiopathic constipation.

Patients and Methods:

Fifty-two patients with chronic idiopathic constipation (according to ROME III criteria) were selected. Patients with diabetes mellitus, hypothyroidism, and hypoparathyroidism were excluded. Each patient took a capsule containing ten 1-3 mm long angiographic guide daily for 6 days. Abdominal x-ray was performed on the seventh day. Remaining markers in each segment were counted and segmental and total colonic transit time was calculated. The analysis was performed by SPSS version 18. In all tests, a P-value less than 0.05 was considered statistically significant.

Results:

The mean age of patients was 36.9 ± 10.1 years. 80.8 % of patients were female. The mean total colonic transit time was 40.8 ±35.1 hours. 34.6 % of patients and 36.5 % of them had prolonged total and segmental colonic transit time.

Conclusions:

We found that prolonged total and segmental colonic transit time is common in patients with chronic idiopathic constipation.

How to interpret a functional or motility test - colon transit study

Measurement of colon transit time is the most basic and primary tool in evaluating disorders of colonic motility. In particular, it is helpful in pathologic diagnosis and for planning management in patients with constipation. Several techniques for measuring colon transit time currently exist. The standard measurement of colon transit time has been performed using radioopaque marker test. The radioopaque marker test is the most widely used method; it is simple to perform as well as being cost effective. But, this technique produces radiation exposure. Radionuclide scintigraphy and wireless motility capsules are other techniques used to measure colon transit time. In radionuclide scintigraphy, the transit of radioisotope is viewed by gamma camera; this approach has an advantage in that it uses minimal radiation and it allows a physiological assessment of gastrointestinal transit. Wireless motility capsules have been validated most recently, but this technique is not useful in Korea. This review presents the techniques used to measure colon transit time and the interpretations provided in different colon transit studies.

Non-compliance does not impair qualitative evaluation of colonic transit time

BACKGROUND

Measurement of colonic transit time (CTT) by using radiopaque markers with the "Multiple ingestion-Single film" technique is a simple, reproducible technique to measure total and segmental CTT. However, it requires good compliance of the patients, who must ingest the capsules containing radio-opaque markers for 6 consecutive days. The purpose of this study was to estimate the error in CTT measurement if they fail to do this.

METHODS

The protocol tested was to ingest 12 markers per day during 6 days and take a plain film of the abdomen on day 7. The study was done by simulation using a 3-compartiment model (right colon, left colon, rectosigmoid area). There was a set of 67,525 possibilities with possible single or double failure of markers ingestion for 6 days either 238,266 combinations for one omission, or 312,375 combinations for two omissions; the absence of omission was the reference. The analysis focused on two complementary aspects of the evaluation of omission: quantitatively, the absolute and relative error on the CTT measured and qualitatively, the diagnostic error (a delayed transit is defined by a total CTT > 65 hours).

KEY RESULTS

Total and segmental CTT measured when omission occurred were greater than the reference time. The difference is particularly important, when omission occurs early during the study for all segments. Qualitative analysis showed that, for one omission of markers ingestion, a correct diagnosis of delayed colonic transit time and of the main site of delay could be obtained by the 3-compartment model in 100% of cases. For two failures of markers ingestion, "delayed" colonic transit could be regarded as normal in only 9.59% of cases; furthermore, the site of delay was correctly recognized in 83% of the cases.

CONCLUSIONS & INFERENCES

Despite omission of markers ingestion for one or two days, measured CTT overestimates the absolute value of colonic transit time, the formulated diagnosis (delayed transit and site of delay) is perfectly acceptable clinically.

Evaluation of gastrointestinal transit in clinical practice: position paper of the American and European Neurogastroenterology and Motility Societies

BACKGROUND

Disorders of gastrointestinal (GI) transit and motility are common, and cause either delayed or accelerated transit through the stomach, small intestine or colon, and affect one or more regions. Assessment of regional and/or whole gut transit times can provide direct measurements and diagnostic information to explain the cause of symptoms, and plan therapy.

PURPOSE

Recently, several newer diagnostic tools have become available. The American and European Neurogastroenterology and Motility Societies undertook this review to provide guidelines on the indications and optimal methods for the use of transit measurements in clinical practice. This was based on evidence of validation including performance characteristics, clinical significance, and strengths of various techniques. The tests include measurements of: gastric emptying with scintigraphy, wireless motility capsule, and (13)C breath tests; small bowel transit with breath tests, scintigraphy, and wireless motility capsule; and colonic transit with radioopaque markers, wireless motility capsule, and scintigraphy. Based on the evidence, consensus recommendations are provided for each technique and for the evaluations of regional and whole gut transit. In summary, tests of gastrointestinal transit are available and useful in the evaluation of patients with symptoms suggestive of gastrointestinal dysmotility, since they can provide objective diagnosis and a rational approach to patient management.

Colonic transit studies: normal values for adults and children with comparison of radiological and scintigraphic methods

The sitz or plastic marker study for colonic transit has been around for many years. It is applicable where an X-ray machine exists, is widely used and is accepted as the gold standard for diagnosing constipation. Recently, radiopharmaceutical methods have been developed. The theme of this review is their possible roles in the assessment of paediatric bowel motility disorders in patients presenting to paediatric surgeons. This review presents data on total and segmental transit in normal adults and children and comparing the two techniques in adults. Reliability and reproducibility are presented. Normative data for colonic transit in adults and children are discussed and parameters for assessing abnormal transit are reviewed. Normal colonic transit takes 20-56 h. Plastic marker studies are more readily accessible, but the assessment may be misleading with current methods. Plastic markers show faster transit than scintigraphy. It is difficult to compare the two techniques because methods of reporting are different. Using scintigraphy, repeatability is good. Separation of normal from slow transit in the ascending colon is apparent at 24 and 48 h, but the determination of transit through the distal colon/rectum in adults may require studies of more than 7 days. In conclusion, plastic marker studies and scintigraphy show similar transit rates in young adults and children. However, scintigraphy has advantages of allowing transit through the stomach and small intestine to be measured and has proved useful in the diagnostic workup of children with intractable constipation.