Luminal Distension Research Articles

Alterações ultraestruturais nas vilosidades do jejuno de equinos após distensão

O objetivo do presente estudo foi analisar as alterações ultraestruturais nas vilosidades do jejuno de seis equinos submetidos à distensão intraluminal com solução salina. A pressão intraluminal foi mantida em 25cm de água durante duas horas. As amostras de mucosa intestinal colhidas às: zero hora; duas horas de distensão; e duas horas e 12h de descompressão foram analisadas por meio de microscopia eletrônica de varredura. Avaliaram-se a área e o perímetro das vilosidades e sua densidade, usando-se um programa computacional de análise de imagens (Image J). A distensão luminal promoveu aumentos da área e do perímetro das vilosidades intestinais. Essa alteração ultraestrutural ocorreu somente 12h após a descompressão e considerou-se que a provável causa seria o edema promovido por aumento da permeabilidade vascular decorrente de um processo de isquemia e reperfusão da mucosa intestinal. Concluiu-se que a distensão intraluminal do jejuno equino promoveu, tardiamente, aumento das dimensões das vilosidades intestinais.

Role of the vagus nerve on the development of postoperative ileus

Postoperative ileus involves reflex inhibition of intestinal motility within hours after surgery and a subsequent intestinal inflammatory response that is characterized by efferent vagal modulation via acetylcholine receptors on intestinal macrophages. We aimed to characterize the role of vagal modulation of intestinal motility during the early hours after surgery. C57BL6 mice underwent laparotomy and standardized small bowel manipulation to induce postoperative ileus. Subgroups were vagotomized 3-4 days prior to experiments or received pharmacological inhibition of the acetylcholine alpha7 subunit with the inhibitor alpha-bungarotoxin, while control animals were sham operated and remained otherwise untreated. Three hours later, a 2-cm jejunal segment was harvested with the mesentery attached. Mesenteric afferent nerve recordings were established in an organ bath generating a multiunit signal with subsequent computerized analysis. Intraluminal pressure was continuously recorded to assess intestinal motility. Afferent nerve responses were quantified at baseline and to chemical stimulation with bradykinin (0.5 microM) or serotonin (5-HT; 500 microM) and following mechanical stimulation by continuous ramp distension to 60 mmHg. Peak amplitudes of intestinal motility and afferent nerve discharge at baseline were not different following chronic vagotomy, alpha-bungarotoxin or sham operation. Maximum afferent discharge to 5-HT following alpha-bungarotoxin was comparable to sham controls, while the response was reduced in chronically vagotomized animals (p < 0.05). Maximum afferent nerve discharge to bradykinin and peak firing during maximum distension at 60 mmHg was similar in the different subgroups. At luminal distension from 10 to 30 mmHg, afferent discharge was lower in vagotomized animals compared to sham controls (p < 0.05) but unchanged after alpha-bungarotoxin. Sensitivity to low-threshold distension and 5-HT is mediated via vagal afferents during postoperative ileus, while sensitivity to high-threshold distension and bradykinin is independent of vagal afferent innervation. Early inhibition of intestinal motility at 3 h after onset of postoperative ileus does not appear to depend on vagal innervation.

Evidence‐based dietary management of functional gastrointestinal symptoms: The FODMAP approach

Functional gastrointestinal symptoms are common and their management is often a difficult clinical problem. The link between food intake and symptom induction is recognized. This review aims to describe the evidence base for restricting rapidly fermentable, short-chain carbohydrates (FODMAPs) in controlling such symptoms. The nature of FODMAPs, their mode of action in symptom induction, results of clinical trials and the implementation of the diet are described. FODMAPs are widespread in the diet and comprise a monosaccharide (fructose), a disaccharide (lactose), oligosaccharides (fructans and galactans), and polyols. Their ingestion increases delivery of readily fermentable substrate and water to the distal small intestine and proximal colon, which are likely to induce luminal distension and induction of functional gut symptoms. The restriction of their intake globally (as opposed to individually) reduces functional gut symptoms, an effect that is durable and can be reversed by their reintroduction into the diet (as shown by a randomized placebo-controlled trial). The diet has a high compliance rate. However it requires expert delivery by a dietitian trained in the diet. Breath hydrogen tests are useful to identify individuals who can completely absorb a load of fructose and lactose so that dietary restriction can be less stringent. The low FODMAP diet provides an effective approach to the management of patients with functional gut symptoms. The evidence base is now sufficiently strong to recommend its widespread application.

A novel TRPV1 receptor antagonist JNJ-17203212 attenuates colonic hypersensitivity in rats

This study examined the efficacy of a novel TRPV1 antagonist, JNJ-17203212, in two experimental rat models that exhibit a hypersensitive visceral motor response (VMR) to colorectal distension (CRD). In the first model, intraluminal administration of acetic acid (1% solution) into the distal colon produced an acute colonic hypersensitivity. In the second model, intraluminal administration of 2,4,6-trinitrobenzenesulfonic acid (TNBS) into the distal colon produced a chronic, post-inflammatory colonic hypersensitivity 30 days post-TNBS administration. Throughout this study, colonic sensitivity was assessed via quantification of VMR to CRD in rats following a single, oral administration of JNJ-17203212 (3, 10 or 30 mg/kg) or vehicle. Intraluminal administration of acetic acid and TNBS resulted in increased VMR to CRD when compared to controls. In both groups, VMR to CRD was significantly reduced by administration of JNJ-17203212 at 30 mg/kg. The results of this study show that the selective TRPV1 antagonist, JNJ-17203212, reduces sensitivity to luminal distension in both an acute, noninflammatory and a chronic, post-inflammatory rodent model of colonic hypersensitivity. These data indicate that TRPV1 is involved in the pathogenesis of visceral hypersensitivity and that JNJ-17203212 may be a potential therapeutic agent for functional bowel disorders characterized by abdominal hypersensitivity, such as irritable bowel syndrome.

Colonoscopy Peer Review Utilizing Automated Video Capture

Purpose: Colonoscopy is the screening modality of choice for detecting early colorectal cancer in the United States. Several retrospective reports show that colorectal cancers may appear within 3 years of a colonoscopy, suggesting some polyps or cancers are missed. Despite these findings, no standardized, validated method exists to objectively evaluate the skill set of an endoscopist. Aim: to evaluate an anonymous, automated video capture system used in conjunction with novel software to facilitate peer review of endoscopic performance, and to see if higher quality exams correlate with withdrawal time. Methods: Existing infrastructure and software were used to capture entire colonoscopies which were then stored as digital video files and reviewed anonymously. Video colonoscopy files were randomly obtained from 2 endoscopy suites at Mayo Clinic-Rochester over the course of 4 days in 2007. Three endoscopists with varied endoscopic experience (1 fellow, 1 junior staff and 1 senior staff) reviewed a set of 24 anonymous video colonoscopies, and provided feedback via a graphical user interface. The 3 reviewers were asked to assign numerical scores on several parameters: adequacy of colonic mucosal visualization including the proximal side of haustral folds, flexures, rectal valves and the ileocecal valve (0-100), adequacy of removal of fluid/feces during exam (0-10), and adequacy of luminal distention during exam (0-10). Additionally, reviewers identified key time points during each colonoscopy and a withdrawal time was calculated. Results: The panel of 3 individual reviewers demonstrated agreement when asked to evaluate 24 random colonoscopy video files of varied quality. Specifically, the intraobserver agreement for the visualization score (0-100) was good, reflected by a disagreement range of 19 ± 13 (Mean+SD). Similarly, scores for adequacy of fluid/feces removal (0-10) and adequacy of luminal distention (0-10), showed good agreement also reflected by low intra-observer disagreement; range 2.0 ± 1.3, and 2.1 ± 1.5 (Mean+SD), respectively. There was no relationship between visualization score and withdrawal time for each reviewed case: least squares analysis showed no correlation between the two (R2 = 0.04). Conclusion: Our results show that a standardized, anonymous method utilizing video capture and new software technology allows effective and consistent peer review of individual colonoscopies. The close agreement among reviewers suggests that this peer review method is independent of the evaluator's experience. Therefore, our method can be used to ensure that an endoscopist meets a minimal standard of quality, assessed in an anonymous and reproducible fashion. Our results question the utility of withdrawal time as a standard for quality. Disclosure: PC de Groen - stock in EndoMetric J Wong - stock in EndoMetric W Tavanapong - stock in EndoMetric J Oh - stock in EndoMetric.

MR Small-Bowel Follow-Through for Investigation of Suspected Pediatric Small-Bowel Pathology

The purpose of our study was to evaluate the potential role of an MR small-bowel follow-through (SBFT) technique in the investigation of suspected pediatric small-bowel abnormalities. Between September 2003 and January 2008, 280 MR SBFT examinations were performed for investigation of known or suspected small-bowel abnormalities, including 19 of 280 examinations in 17 children (mean age, 13 years; age range 6-17 years), representing the current study population. A standardized technique was used in all cases, including axial and coronal steady-state free precession acquisitions at successive time intervals until completion. Retrospective analysis of the studies obtained was performed by two radiologists, who blindly and independently scored predefined small-bowel segments according to the degree of luminal distention achieved. Any pathologic lesions detected were also noted. Indicators of examination success as a whole (volume, tolerability, and side effects of oral contrast material) were also noted, as were details pertaining to examination duration (number of visits to the MR table, total table time). Oral contrast medium was ingested and subsequent imaging was possible in all patients; 84.2% of patients tolerated the oral contrast material well and 15.8% showed moderate tolerance. The MR table time ranged from 2 to 4 minutes, without early termination of the examination in any case. The average number of visits to the MR table was 1.3 (range, 1-3). The mean duration for complete small-bowel evaluation was 25 minutes (range, 20-60 minutes). The mean distention scores were well within the diagnostic range in all small-bowel segments for both observers, with a substantial degree of interobserver agreement in score assignment (kappa = 0.73). Pathologic lesions were identified in 53% of studies. MR SBFT represents a promising, and perhaps optimal, technique for pediatric small-bowel evaluation for a variety of reasons, including its high tolerability, lack of ionizing radiation, avoidance of duodenojejunal intubation, and excellent luminal distention achieved. Furthermore, this technique allows "pseudodynamic" functional imaging while also showing extraluminal disease, without known biologic risk.

MR Colonography after Oral Administration of Polyethylene Glycol–Electrolyte Solution

This prospective study was approved by the local institutional ethics committee, and written informed consent was obtained from all patients. The aim of this study was to determine whether the oral administration of a polyethylene glycol (PEG)-electrolyte solution induces adequate luminal distention for magnetic resonance (MR) colonography to be performed and to assess patient acceptance of this procedure. Fifty-five patients (26 women, 29 men; mean age, 60.5 years +/- 14 [standard deviation]; age range, 40-75 years) who were referred for optical colonoscopy (OC) owing to symptoms and findings that included rectal bleeding, altered bowel habits, and positive fecal occult blood test results participated in this study. Standard bowel preparation was performed 1 day before the procedure. MR colonography was performed and followed by OC on the same day. Before undergoing MR colonography, the patients received 2.0-2.5 L of the PEG-electrolyte solution orally. Adequate distention of all colonic segments was achieved in 50-53 (91%-96%) of patients imaged in the supine position and in 51-53 (93%-96%) of patients imaged in the prone position. Oral administration of the solution yielded uniform luminal darkening and sufficient colonic distention for MR colonography in 91%-96% of patients.

A novel herbal preparation desensitizes mesenteric afferents to bradykinin in the rat small intestine

Herbal preparations are evolving as promising agents for the treatment of functional gastrointestinal disorders which are considered to be secondary to visceral hypersensitivity. We aimed to determine whether a new combination of six herbal extracts reduces the sensitivity of intestinal afferents in rat. Male Wistar rats (250-350 g, n = 6 per group) were gavaged with either vehicle or 2.5, 5 or 10 mL kg(-1) of STW 5-II, a herbal preparation which contains six extracts. Two hours later, animals were anaesthetized and extracellular multi-unit mesenteric afferent nerve recordings were obtained in the proximal jejunum in vivo. Afferent discharge to 5-hydroxy-tryptamine (5-HT) (5, 10, 20 and 40 microg kg(-1), i.v.), luminal distension (0-60 mmHg) and bradykinin (BK) (15, 30 and 60 microg kg(-1), i.v.) was recorded. At baseline, spontaneous afferent discharge was not different following pretreatment with the various doses of STW 5-II compared with vehicle. The pressure-dependent increase in afferent discharge to intraluminal ramp distension and the dose-dependent increase in afferent firing following 5-HT were also uninfluenced by STW 5-II pretreatment. In contrast, the afferent nerve responses to 15, 30 and 60 microg kg(-1) of BK were reduced following 10 mL kg(-1) STW 5-II with peaks at 106 +/- 19, 153 +/- 22 and 156 +/- 25 imp s(-1) compared with 160 +/- 15, 228 +/- 14 and 220 +/- 16 imp s(-1) following vehicle pretreatment (mean +/- SEM, P < 0.05). Intestinal afferent sensitivity to BK which plays a prime role in nociception was reduced following STW 5-II. Thus, STW 5-II may be of therapeutic use for conditions that involve neuronal hypersensitivity and the release of BK in the intestine.

Intestinal Afferent Nerve Sensitivity is Increased During the Initial Development of Postoperative Ileus in Mice

IntroductionNeuronal reflex inhibition of gastrointestinal motility is a key mechanism in the development of postoperative ileus (POI). The aim of our study was to determine whether intestinal afferent nerve fibers are sensitized during the first hours after surgery contributing to this mechanism. MethodsUnder enflurane anesthesia, C57BL/6 mice underwent laparotomy followed by sham treatment or standardized small bowel manipulation to induce POI. After 1, 3, or 9 h, extracellular multi-unit mesenteric afferent nerve recordings were performed in vitro from 2 cm segments of jejunum (subgroups n = 6) superfused with Kreb’s buffer (32°C, gassed with O2/CO2 mixture). Segments were cannulated to monitor luminal pressure and intestinal motility. Afferent impulses as response to bradykinin (0.5 μM) and to mechanical ramp distension of the intestinal lumen from 0 to 80 cmH2O were recorded. ResultsAt 1 h, amplitudes of intestinal contractions were 0.8±0.2 cmH2O after induction of POI and 5.0±0.8 cmH2O in sham controls (mean ± SEM; p < 0.01). A similar difference was observed for segments harvested at 3 and 9 h. Afferent firing to serosal bradykinin was increased at 1, 3, and 9 h in POI segments compared to sham controls (p < 0.05 at 1 h, p < 0.01 at 3 and 9 h). During distension with high pressures, afferent firing rate was increased at 1 and 3 h in segments after induction of POI compared to sham controls. Nine hours postoperatively, contracted and dilated segments were observed during POI that were investigated separately. While afferent firing in dilated segments was increased to 176 ± 16 imp s−1 at 80 cmH2O luminal distension (p < 0.01), it was 46 ± 5 imp s−1 in contracted segments (p < 0.001) compared to 77 ± 4 imp s−1 in sham controls. ConclusionsAfferent firing to bradykinin and high threshold distension is augmented in the early phase of POI. As these stimuli are known to sensitize predominantly spinal afferents, this mechanism may contribute to reflex inhibition of intestinal motility during POI.

Routine use of modified CT Enterography in patients with acute abdominal pain

Purpose To evaluate routine use of CT Enterography (CTE) in patients presenting with non-traumatic acute abdominal pain with respect to patient tolerance, imaging of intestinal detail along with conventional abdominal evaluation. Materials and methods Modified CTE was performed in 165 consecutive patients with acute abdominal pain: ingestion, as tolerated, of 900–1200 ml of 2% barium suspension + 5 ml of Gastrografin over 45 min; 150 ml of iv contrast given in two boluses (50 and 100 ml) 3 min apart (split bolus injection protocol). Axial, coronal and sagittal reformats were reviewed by two radiologists and graded on a 5-point scale (5 best) in regard to GI tract luminal opacification and distension and abdominal organ and vascular enhancement. Results In 81 patients the cause of abdominal pain was identified (intestinal in 54 and extraintestinal in 27). Oral contrast reached cecum in 76% of the patients and the small bowel was well distended and opacified (medians = 4). Mucosa detail was good (median = 3) and there was significant ( p < 0.0001) correlation between bowel opacification and distension for both jejunum and ileum. A combined nephrographic and excretory phase was achieved (medians 4 and 5, respectively), while the great vessels were well opacified, allowing for vascular evaluation (median = 5). The rest of the abdominal structures were well visualized. Conclusion Modified CTE is well tolerated by patients with acute non-traumatic abdominal pain, and can be used routinely as a non-invasive examination informative of bowel, vessel and organ pathology in Emergency Department patients.

Lubiprostone for constipation and irritable bowel syndrome with constipation

Chronic constipation and irritable bowel syndrome are heterogeneous disorders characterized by altered bowel habits, abdominal discomfort and/or difficult defecation. These conditions have a significant impact on patients’ quality of life, as well as on the US economy, both in terms of healthcare costs and lost productivity. Treatment typically begins with lifestyle changes, increased fiber intake and osmotic and stimulant laxative intake. However, treatments for constipation vary in terms of their efficacy and safety. Furthermore, surveys of physicians and patients have revealed a strong desire for improved therapeutic options. Lubiprostone is a synthetic bicyclic fatty acid that is gut selective and stimulates type 2 chloride channels, resulting in increased chloride, sodium and water secretion into the lumen. The increased fluid secretion causes luminal distension, secondary peristalsis and laxation. Randomized Phase III trials have shown that lubiprostone is efficacious in the treatment of chronic idiopathic constipation and irritable bowel syndrome with constipation. The US FDA has approved lubiprostone at a dose of 24 µg twice daily for the treatment of chronic idiopathic constipation in adults, and at a dose of 8 µg twice daily for irritable bowel syndrome with constipation in adult women. Nausea, diarrhea and headaches are the most commonly reported side effects. In long-term studies, lubiprostone appears to be safe.

MRI of the small bowel: can sufficient bowel distension be achieved with small volumes of oral contrast?

Sufficient luminal distension is mandatory for small bowel imaging. However, patients often are unable to ingest volumes of currently applied oral contrast compounds. The aim of this study was to evaluate if administration of low doses of an oral contrast agent with high-osmolarity leads to sufficient and diagnostic bowel distension. Six healthy volunteers ingested at different occasions 150, 300 and 450 ml of a commercially available oral contrast agent (Banana Smoothie Readi-Cat, E-Z-EM; 194 mOsmol/l). Two-dimensional TrueFISP data sets were acquired in 5-min intervals up to 45 min after contrast ingestion. Small bowel distension was quantified using a visual five-grade ranking (5 = very good distension, 1 = collapsed bowel). Results were statistically compared using a Wilcoxon-Rank test. Ingestion of 450 ml and 300 ml resulted in a significantly better distension than 150 ml. The all-over average distension value for 450 ml amounted to 3.4 (300 ml: 3.0, 150 ml: 2.3) and diagnostic bowel distension could be found throughout the small intestine. Even 45 min after ingestion of 450 ml the jejunum and ileum could be reliably analyzed. Small bowel imaging with low doses of contrast leads to diagnostic distension values in healthy subjects when a high-osmolarity substance is applied. These findings may help to further refine small bowel MRI techniques, but need to be confirmed in patients with small bowel disorders.

Differential Sensitization of Afferent Neuronal Pathways During Postoperative Ileus in the Mouse Jejunum

Postoperative ileus induces reflex inhibition of gastrointestinal motility and an intestinal inflammatory response. We aimed to determine whether afferent sensitivity is increased during postoperative ileus and whether alterations are cyclooxygenase-2 (COX-2)-dependent. C57BL/6 mice underwent laparotomy followed by standardized small bowel manipulation to induce ileus or sham treatment. After 24 hours, extracellular multiunit mesenteric afferent nerve discharge was recorded in vitro from 2-cm segments of jejunum. Fos immunoreactivity was determined for neuronal activation in the vagal nucleus of the solitary tract (nTS) of the brain stem and leukocyte infiltration in the intestinal muscularis by myeloperoxidase stains. Serosal bradykinin (1 microM) was followed by an increase in afferent discharge to 65 +/- 5 imp x s(-1) in ileus segments compared with 37 +/- 6 imp x s(-1) in sham controls (P < 0.05). The response was attenuated to 31 +/- 7 imp x s(-1) after the selective COX-2 inhibitor 5,5-dimethyl-3-(flurorophenyl)-4-(4-methylsulfonyl) phenyl-2(5H)-furanone (DFU) in ileus segments. Afferent firing during ileus was augmented at luminal distension at 20 mm Hg but not at pressures up to 60 mm Hg. The number of Fos-positive neurons in the nTS was 110 +/- 45 during ileus compared with 7 +/- 4 in sham controls (-7.32 mm from bregma, P < 0.05) and did not differ after DFU. The intestinal muscularis contained more leukocytes during ileus compared with ileus segments after DFU and controls (both P < 0.05). This study provides direct evidence from afferent nerve recordings that sensitivity to bradykinin, which stimulates predominantly spinal afferents, is augmented during postoperative ileus involving a COX-2 pathway. Vagal afferents were also sensitized because low-threshold mechanosensitivity and neuronal activation in the nTS were increased.

Quality Assessment for CT Colonography: Validation of Automated Measurement of Colonic Distention and Residual Fluid

The purpose of this study was to validate automated quality assessment (QA) software for CT colonography (CTC) by comparing results obtained with the software with results of interpretation by radiologists in the assessment of colonic distention and surface area obscured by residual fluid. CTC scans of 30 patients were selected retrospectively to span ranges of luminal distention (well distended to poorly distended) and surface area covered by residual fluid (high amount of coverage to low amount of coverage). We used QA software developed in our laboratory to automatically measure the mean distention of each of five colonic segments (ascending, transverse, descending, sigmoid, and rectum). Three experienced radiologists visually graded each scan for distention and fluid coverage. Distention and fluid scores for specific segments were assessed with Bland-Altman analysis (mean difference with 95% limits of agreement) and the weighted kappa test. Interobserver and intraobserver variability was determined with the weighted kappa test. For distention scoring, the mean difference between radiologists and the QA software was 0.1% (95% limits of agreement, -25.6% and 25.9%). For fluid scoring, the mean difference was -0.6% (95% limits of agreement, -8.2% and 7.1%). There was moderate to good agreement (weighted kappa value, 0.50-0.78) between the radiologists' mean scores and the scores obtained with the QA software and for interreader and intrareader assessments of distention and fluid coverage. Results with the QA software agreed with radiologists' assessment of colonic distention and residual fluid coverage but were a more objective assessment. Use of this QA software can help standardize two important factors, distention and residual fluid coverage, that affect the quality of CTC, reducing two known causes of poor CTC performance.

Differential effects of ASIC3 and TRPV1 deletion on gastroesophageal sensation in mice

Using a recently developed in vitro preparation of vagal afferent pathways, we examined the role of TRPV1 and ASIC3 on the mechano- and chemosensitive properties of gastroesophageal sensory neurons. Esophagus, stomach, and the intact vagus nerves up to the central terminations were carefully dissected from TRPV1 and ASIC3 knockout mice and wild-type controls. The organ preparation was placed in a superfusion chamber to obtain intracellular recordings from the soma of nodose neurons during luminal stimulation of esophagus and stomach. The proximal esophagus and distal stomach were separately intubated to allow perfusion and graded luminal distension. In wild-type mice, mechanosensitive neurons were activated by low distension pressures and encoded stimulus intensity over the entire range tested. Luminal acidification significantly transiently increased the resting frequency but did not alter responses to subsequent mechanical stimulation. ASIC3 and TRPV1 knockout significantly blunted responses to distension compared with wild-type controls, with deletion of TRPV1 having a more significant effect than ASIC3 deletion. Luminal acidification did not activate mechanosensory neurons in ASIC3 and TRPV1 knockout mice. Our data demonstrate a role of TRPV1 in chemo- and mechanosensation of gastroesophageal afferents. ASIC3 may contribute to acid sensation but plays a more subtle role in responses to distending stimuli. Considering the importance of acid in dyspeptic symptoms and gastroesophageal reflux, TRPV1 or ASIC3 may be an attractive target for treatment strategies in patients who do not respond to acid suppressive therapy.

Assessment of colon sensitivity by luminal distension in mice

Colorectal distension (CRD) is a widely used and reliable method for evaluating colon sensitivity in unanesthetized animals, including humans. Hollow organ distension is a mechanical stimulus that replicates in humans the sensation and pattern of referral of their visceral pain. In animals, CRD has been employed to evaluate drug efficacy, strain, sex or genetic differences and changes in colon sensitivity after inflammation or irritation of the distal colon. Responses to CRD are measured as electromyographic (EMG) recordings of the abdominal musculature, termed the visceromotor response. This protocol will provide sufficient detail to allow an investigator to surgically prepare a mouse for CRD, construct distending balloons, distend the colon, and accumulate and analyze data from EMG recordings; examples are also provided to illustrate typical experimental outcomes. CRD recording sessions are typically 2 h in duration.

Comparison of MR enteroclysis with MR enterography and conventional enteroclysis in patients with Crohn’s disease

To prospectively compare the diagnostic accuracy of MR enteroclysis with duodenal intubation with MRI after drinking oral contrast agent only (MR enterography) with conventional enteroclysis (conv-E) as reference standard in patients with Crohn's disease. Forty consecutive patients (22 males and 18 females; mean age 36; range 16-74 years) with proven Crohn's disease underwent conv-E and MR imaging. Twenty-two patients underwent MR enteroclysis with intubation (MRE) and 18 underwent MR-enterography (MR per OS). Two radiologists reached a consensus about the following imaging findings: luminal distension and visualization of superficial mucosal, mural and mesenteric abnormalities. Standard descriptive statistics and a Wilcoxon rank sum test were used. Statistical significance was inferred at P < 0.05. There was no significant difference in the adequacy of luminal distention between the MRE and conv-E (P = 0.08), and both were statistically superior in comparison to MR per OS in the distension of the jejunum (P < 0.01) and less significant at the ileum and terminal ileum levels (P < 0.05). MRE and conv-E were comparable for the accuracy of superficial mucosal abnormalities; meanwhile conv-E compared with MR per OS was statistically superior (P < 0.01). MRE compared with MR per OS was statistically better when visualizing superficial abnormalities (P < 0.01). No statistically significant differences were found in assessing the diagnostic efficacy between MR examinations for the depiction of mural stenosis (P = 0.105) and fistulae (P = 0.67). The number of detected mesenteric findings was significantly higher with both MRE and MR per OS compared to conv-E (P < 0.01). MRE can serve as the diagnostic procedure for initially evaluating patients suspected of having Crohn's disease. MR per OS may have a role in patients that refuse or have failed intubation and also for follow-up.

Malignant Rectal Polyp Overlooked on CT Colonography Because of Retention Balloon: Opposing Crescent Appearance as Sign of Compressed Polyp

WEB This is a Web exclusive article. bscuration of rectal lesions by a rectal catheter or by its retention balloon is a well-established diagnostic pitfall at barium enema examination that often requires deflation of the balloon or removal of the catheter to obtain an unobscured view [1]. Rectal lesions missed at CT colonography (CTC), on the other hand, are rare because of the relatively small size of the rectal catheter, the proclivity of the rectum for adequate luminal distention, and the fact that a retention balloon is not needed in most patients [2]. Although a retention balloon is not necessarily required for CTC, it may be helpful for optimal colonic distention in a select group of patients with insufficient anal sphincteric tone. Its use, however, may pose another potential source of false-negative results. A distended retention balloon may compress a rectal polyp against the wall of the rectum, thereby altering the gross morphology of the lesion and allowing the polyp to escape detection on CTC review. To our knowledge, the occurrence of a rectal polyp being compressed by a retention balloon or of a rectal polyp being compressed to the degree that was seen in our patient has not been reported. We report a case whereby a 12mm polypoid rectal adenocarcinoma arising in a tubular adenoma was missed both prospectively and retrospectively at CTC performed using an inflated retention balloon. We also suggest a finding at CTC that may help correctly identify a retention balloon–induced compressed polyp.

Spontaneous and Bolus-induced Motility in the Chronically Obstructed Guinea-Pig Small Intestine In vitro

Partial obstruction of the small intestine results in dysmotility and morphometric changes proximal to the site of obstruction. However, our understanding of the relation between the morphometric remodeling and change in the motility pattern during chronic obstruction is sparse. The aim of this study was to investigate the effect of partial chronic intestinal obstruction on motility, morphology, and collagen content proximal and distal to the site of obstruction. Twenty guinea-pigs with partial intestinal obstruction and eight sham-operated controls lived for four weeks. Spontaneous and bolus-induced motility was recorded in isolated intestinal segments proximal and distal to the site of obstruction using a perfused low-compliance pressure-measuring system in vitro. After the motility experiments, the specimens were fixed at 2 kPa luminal distension pressure and sampled for histomorphometric determination of luminal radius, layer thickness, and wall thickness. Total wall collagen was also determined. The area under the curve (AUC) of spontaneous contractions and the amplitude, frequency, and AUC for the bolus-induced motility were higher in the proximal segments of the banded animals compared to distal segments and to the intestinal segments in the control animals (P < 0.05). The radius-to-thickness ratio was lowest in the proximal segments of the obstructed animals (P < 0.01). The collagen content was three times higher proximal to the site of obstruction when compared to distal locations and to the controls (P < 0.01). The AUC at 2 ml bolus injections plotted against the radius-to-thickness ratio showed a strong association (r = 0.97 for control, and r = 0.99 for obstruction, P < 0.01). No correlation was found between the collagen content and AUC. In conclusion, partial intestinal obstruction in guinea pigs caused pronounced changes in morphology and motility. An association was found between the radius-to-thickness ratio and bolus-induced motility.

Position changes improve visibility during colonoscope withdrawal: a randomized, blinded, crossover trial

Adequate distension is essential to maximize neoplasia detection during colonoscope withdrawal. Position changes may improve distension but are often not performed in routine practice. To assess whether routine position changes improve luminal distension during colonoscope withdrawal. Randomized, blinded, crossover trial. Single tertiary-referral center, United Kingdom. Fourteen patients attending for routine colonoscopy. Videotaped, back-to-back examination of colon proximal to rectosigmoid junction in left lateral position only, then with position changes: left lateral for the cecum to the hepatic flexure, supine for the transverse colon, and right lateral for the splenic flexure and the descending colon, or vice versa. Luminal distension as scored by a blinded video reviewer. Luminal distension was scored on a scale of 1 to 5 for each colonic area: 1, complete collapse; 5, widely distended to limit of view. A score of 2 or less was considered inadequate for diagnosis. Scores for the 2 examinations from the blinded video reviewer were significantly higher in the transverse, the splenic flexure, and the descending colon, P = .02, .002, and <.001, respectively. Without position changes, 6 of 14 of patients (43%) would have had a nondiagnostic distension score (1 or 2) in at least 1 colonic area, P = .03. Nonvalidated scoring system for luminal distension, however, good agreement between endoscopist and blinded reviewer, weighted kappa 0.53, 95% confidence interval 0.38-0.69. Position change, a cost-neutral intervention, during colonoscope withdrawal improved luminal distension between hepatic flexure and sigmoid-descending junction and has the potential to reduce adenoma and early cancer miss rates.