Colonoscopic Technique Research Articles

Improving the utility of colonoscopy: Recent advances in practice.

Colonoscopy is a frequently performed diagnostic and therapeutic test and the primary screening tool in several nationalized bowel cancer screening programs. There has been a considerable focus on maximizing the utility of colonoscopy. This has occurred in four key areas: Optimizing patient selection to reduce unnecessary or low yield colonoscopy has offered cost-benefit improvements in population screening. Improving quality assurance, through the development of widely accepted quality metrics for use in individual practice and the research setting, has offered measurable improvements in colonoscopic yield. Significant improvements have been demonstrated in colonoscopic technique, from the administration of preparation to the techniques employed during withdrawal of the colonoscope. Improved techniques to avoid post-procedural complications have also been developed-further maximizing the utility of colonoscopy. The aim of this review is to summarize the recent evidence-based advances in colonoscopic practice that contribute to the optimal practice of colonoscopy.

Should Assessment of Quality Indicator of Colonoscopy Be Varied Depending on the Colonoscopic Technique Level?

The purpose of this research was to evaluate if withdrawal time is a useful index in spite of differences in gastroenterologists' ability and if there are other quality indicators of colonoscopy. A total of 665 consecutive, asymptomatic individuals of average risk between 50 and 75 years of age who underwent screening colonoscopies performed by 12 gastroenterologists were included in this study. The endoscopists were classified to either the experienced group (group A, N = 6) or the under-experienced group (group B, N = 6). The endoscopists were unaware that they were being studied during the two-month study period. In group A, adenoma detection rate was 0.56, while in group B it was 0.43 (P = 0.048). The mean withdrawal time ranged widely from 4.2 to 10.3 min per patient with a mean value of 6.83 for group A and 6.54 for group B. There was a significantly positive relationship between the number of adenomas detected and the withdrawal time for group B (r = 0.827, P = 0.005), but not for group A (r = -0.152, P = 0.584). In the case of group A, the ratio of cecal intubation time to withdrawal time (I/E ratio) less than 1 showed significantly correlated adenoma detection rate compared to I/E ratio greater than 1 (r = -0.308, P = 0.036). In the case of group B, mean I/E ratio was 1.7 and all endoscopists' I/E ratios were greater than 1. For experienced endoscopists, a useful supplementary quality indicator of colonoscopy is to keep intubation/withdrawal time ratio less than 1 and it is necessary for under-experienced endoscopists to try to keep enough withdrawal time.

PMO-211 Propofol sedation for colonoscopy: a single centre's experience

IntroductionGI endoscopy has been widely practiced for nearly 40 years. Techniques and sedation regimes have advanced together with an ever increasing complexity of therapeutic possibilities. Despite improved colonoscopic technique there...

NBI versus hochauflösende Endoskopie in der Diagnostik von Neoplasien bei Colitis ulcerosa

BACKGROUND AND STUDY AIMS: Controversy exists about which colonoscopic technique is most sensitive for the diagnosis of neoplasia in patients with ulcerative colitis. We compared new-generation narrow-band imaging (NBI) to high-definition endoscopy (HDE) for the detection of neoplasia and evaluated NBI for the differentiation of neoplastic from non-neoplastic mucosa. PATIENTS AND METHODS: Randomized crossover trial in which patients with ulcerative colitis under-went both NBI and HDE colonoscopy in random order with at least 3 weeks between the two procedures, which were performed by different endoscopists. Lesions detected during the first examination were left in situ in order to enable detection during the second examination as well. Main outcome measures were (1) neoplasia detection, and (2) diagnostic accuracy of NBI for -differentiating neoplastic from non-neoplastic mucosa by using the Kudo classification and vascular pattern intensity (VPI). RESULTS: Twenty-five patients were randomized to undergo HDE first and 23 to undergo NBI first. Of 16 neoplastic lesions, 11 (69 %) were detected by HDE and 13 (81 %) by NBI (P = 0.727). Of 11 patients with neoplasia, 9 (82 %) were diagnosed by HDE and 8 (73 %) by NBI (P = 1.0). The sensitivity, specificity, and accuracy of the Kudo classification were 76 %, 66 % and 67 %. Corresponding figures for VPI were 80 %, 72 % and 73 %. CONCLUSION: NBI does not improve the detection of neoplasia in patients with ulcerative colitis compared to HDE. In addition, NBI proves unsatisfactory for differentiating neoplastic from non-neoplastic mucosa.

RESPONSIVE INSERTION TECHNOLOGY

The colonoscopic insertion technique is still one of the most difficult endoscopic procedures to master and development of a new colonoscope that is easier to insert is much awaited especially into the cecum without patient discomfort. We focused on reducing patient pain and boosting the success rate of colonoscope insertion into the cecum in complicated cases. As a result, we have successfully developed two mechanisms: "Passive Bending" and use of a "High Force Transmission insertion tube." We believe these two mechanisms when combined together will contribute to a reduction in patient discomfort and an increase in the cecal intubation rate during many difficult colonoscopies, but further evaluation is required with respect to therapeutic endoscopy effectiveness and insertion for patients with long colons.

Narrow-band imaging versus high-definition endoscopy for the diagnosis of neoplasia in ulcerative colitis

Controversy exists about which colonoscopic technique is most sensitive for the diagnosis of neoplasia in patients with ulcerative colitis. We compared new-generation narrow-band imaging (NBI) to high-definition endoscopy (HDE) for the detection of neoplasia and evaluated NBI for the differentiation of neoplastic from non-neoplastic mucosa. Randomized crossover trial in which patients with ulcerative colitis underwent both NBI and HDE colonoscopy in random order with at least 3 weeks between the two procedures, which were performed by different endoscopists. Lesions detected during the first examination were left in situ in order to enable detection during the second examination as well. Main outcome measures were (1) neoplasia detection, and (2) diagnostic accuracy of NBI for differentiating neoplastic from non-neoplastic mucosa by using the Kudo classification and vascular pattern intensity (VPI). Twenty-five patients were randomized to undergo HDE first and 23 to undergo NBI first. Of 16 neoplastic lesions, 11 (69 %) were detected by HDE and 13 (81 %) by NBI ( P = 0.727). Of 11 patients with neoplasia, 9 (82 %) were diagnosed by HDE and 8 (73 %) by NBI ( P = 1.0). The sensitivity, specificity, and accuracy of the Kudo classification were 76 %, 66 % and 67 %. Corresponding figures for VPI were 80 %, 72 %, and 73 %. NBI does not improve the detection of neoplasia in patients with ulcerative colitis compared to HDE. In addition, NBI proves unsatisfactory for differentiating neoplastic from non-neoplastic mucosa.

M1402: “Water Navigation Colonoscopy” Water Navigates the Colonoscope Straightly From the Rectum to the Descending After Complete Removal of Air From the Rectosigmoid

Colonoscopy is a difficult examination to conduct for inexperienced examiners. Improving the view, over insufflation of air causes elongation or acute angulations of the colon and makes passage of the scope difficult. Sakai was the first to describe a simple colonoscopic technique, “Water pouring method” using water infusion instead of air insufflation. This method allows easier negotiation of the scope, but the water surface and the residues in the colon spoils the vision. We have modified this technique to simplify the procedure further by combining water infusion with complete air suction from the rectosigmid and reported a sedative-risk-free colonoscopy insertion technique, “COLLAPSE-SUBMERGENCE METHOD” (Dig Endosc 19(1) 43-48, 2007). Sedation is still an usual practice for colonoscopy, but it includes escort requirement, time needed for recovery and post examination activity restrictions

Characterization of Colonoscopic Tactile Forces: Quantitative Differentiation of Colonoscopy Technique Among Experienced Endoscopists

Colonoscopy requires a skilled endoscopist to use visual and tactile information to advance and withdraw the instrument through a series of fixed and stationary loops. Development and retention of the skills necessary to perform colonoscopy safely and effectively requires extensive training and ongoing education. Quantification of tactile information provides the opportunity to measure the "feel” used by the endoscopist to perform colonoscopy, identify force application patterns, enhance training and improve performance. The purpose of this study is to evaluate a push-pull force and torque measuring device that grips the colonoscope shaft and wirelessly transmits and records all forces applied by the endoscopist during colonoscopy. Methods: The Colonoscopy Force Monitor™ (CFM) is a novel handheld device that attaches to the colonoscope and measures applied forces. The device enables the endoscopist to maintain a conventional hand position and uses an electronically controlled grip and release mechanism to fix the CFM position on the instrument. Four expert endoscopists performed colonoscopy in 20 patients. There were 13 men and 7 women with a mean age 56.0 ± 11.4 yrs. Results: Mean time to cecum was 10.0 ± 5.0 min, and mean meperidine and midazolam doses were 42.9 ± 11.6 mg and 2.5 ± 0.8 mg, respectively. Pain score assessed by the endoscopist, nurse and patient on a scale of 1-4 (1=none, 4=severe) was 1.4. Median push and pull forces were 16.2 and -18.8N with peak force of 34.0 for push and -37.7N for pull, respectively. Maximum clockwise and counter-clockwise torques were 0.47Nm and -0.42Nm with peak torque force of 0.83 and -0.88Nm, respectively. For each endoscopist and for each case both maximum force and force impulse were calculated and plotted. These calculations and plots were used to evaluate the pattern of force application used by each endoscopist. The mean force impulse pattern was not different between male and female patients. However, there were clear differences in maximum push/pull force and torque and force impulse distribution among endoscopists. Conclusion: The present study describes the clinical application of a novel device for measurement of the applied forces during colonoscopy. The device provides comprehensive quantitiative tactile data about performance. The CFM generated data distinguishes patients and endoscopists and could lead to an improved understanding of colonoscopic technique. Further development and clinical use of the CFM are likely to contribute to improved performance and enhancec education by quantifying the force application techniques.(Grant Support NIH/NIDDK SBIR 5R44DK068936-03)

Variation in Colonoscopic Technique and Adenoma Detection Rates at an Academic Gastroenterology Unit

The purpose of this research is to evaluate the quality of colonoscopy at an academic institution with a focus on factors influencing withdrawal times and adenoma detection rates. Procedural data and pathologic results of 550 consecutive screening colonoscopies in average risks patients (mean [+/-SD] age, 57 +/- 7.6, 44% male) completed by ten academic gastroenterologists were reviewed. Per individual gastroenterologist, the adenoma detection rates ranged widely from 0.09 to 0.82 adenomas per patient with a mean of 0.46 for the group. The mean withdrawal time was 7.0 min for the group and ranged from 3.4 to 9.6 min. There was a significant positive relationship between the number of adenomas detected and the withdrawal time (P = 0.006). Endoscopists with cecal intubation time to withdrawal time ratios of less than 1 detected significantly more adenomas compared to endoscopists with ratios greater than 1 (P = 0.001). (1) Significant variation in academic gastroenterologists' abilities to detect adenomas during screening colonoscopies exists. (2) Colonoscopic withdrawal time and the cecal intubation to withdrawal time ratio are important factors associated with increased adenoma detection rates.

Factors That Influence Colonoscopic Technique and Adenoma Detection Rates At An Academic Gastroenterology Unit

Introduction: Colonoscopy is the dominant screening exam for colorectal cancer. Recent publications have highlighted the significant variation in colonoscopic withdrawal times and adenoma detection rates among gastroenterologists. The purpose of this study was to evaluate the quality of colonoscopy at a tertiary academic institution with a focus on factors influencing withdrawal times and adenoma detection rates. Methods: This is a review of the procedural data and pathologic results of 550 consecutive screening colonoscopies in average risks patients (mean [ ± SD] age, 57 ± 7.6, 44 % male) completed between 10/2/06 to 3/15/07 by 10 board certified gastroenterologists. The colonoscopies were all morning procedures completed by staff attending endoscopists only. Endoscopist's experience, cecal intubation time, withdrawal time, and time of day the procedure started were examined to study their effect on adenoma detection rates. Results: Two hundred twenty five (41%) patients had at least one polyp found. One hundred twenty one patients (22 %) had at least one adenoma detected. Advanced lesions (adenomas ≥10 mm in size or with advanced pathology) were found in 25 (4.5%) patients. Colon cancer was detected in 3 (0.5%) patients. Per individual gastroenterologist, the adenoma detection rates (number of adenomas detected per patient screened) ranged widely from .09 to .82 with a mean of .46 for the group. The mean withdrawal time was 7.0 minutes for the group and ranged from 3.4 to 9.6 minutes. There was a significant positive relationship between the number of adenomas detected and the withdrawal time, with more adenomas detected the longer the colonoscopic withdrawal time (P < .01). There was a significant inverse relationship between cecal intubation time and withdrawal time, with shorter withdrawal times associated with longer times taken to reach the cecum (P < .01). Endoscopist's years of experience and hour of day procedure performed did not have a significant influence on withdrawal times, cecal intubation times or adenoma detection rates. Conclusions: 1) Significant variation in gastroenterologists' abilities to detect adenomas during screening colonoscopies exists. 2) Colonoscopic withdrawal time is the most important factor associated with increased adenoma detection rates. 3) It is paramount that future research and endoscopic training focus on increasing adenoma detection rates as well as decreasing interexaminer variation.

Advances in the colonoscopic imaging and endoluminal treatment of early colorectal cancer

In the 40 years since its introduction, colonoscopy has revolutionized the detection of colorectal cancer and its precursors. Recent advances in colonoscopic technique have had an important effect on histopathology, (e.g. type of colorectal specimen derived, new interpretative information produced by endoscopists). The authors are endoscopists who use these new techniques to provide histopathologists with relevant information: the Paris classification of endoscopically visualised lesions, the Kudos classification of pit pattern, the technique of endoscopic mucosal resection, and the management implications of the different classifications.

Splenic injury after colonoscopy

Splenic injury is a rare and serious complication of colonoscopy. The most likely mechanism is tension on the splenocolic ligament and adhesions. Eight cases were identified among claims for compensation submitted to the Danish Patient Insurance Association during the period 1992-2006, seven of which were reported after 2000. The total number of colonoscopies in Denmark in 2004 was 39 067. Seven of the eight patients were aged 65 years or over. Loops causing difficulties during the colonoscopy had been reported in four patients. All the patients had a symptom-free interval after the colonoscopy, ranging from 4 hours to 7 days, before presenting with signs of splenic injury. In all cases the spleen was torn, and the amount of blood in the peritoneal cavity ranged from 1500 mL to 5000 mL. Two patients died postoperatively. The number of cases reported after 2000 indicates that this potentially lethal complication might be more common than was previously assumed, and it is possibly under-reported. Preventive measures include good colonoscopic technique to avoid loop formation and the use of excessive force; and it is possible that emerging endoscopic technologies will lead to a reduced risk of splenic injury. The information given to patients both before and after the procedure should include information on the signs of this complication, and patients should be also informed that these signs can develop after a symptom-free interval.

Assistance of Colorectal Stent Insertion by Sphincterotome

Palliation of patients with unresectable colorectal carcinoma is an effective treatment and technical failure is undesirable. Insertion of colorectal stent using a combined radiologic and colonoscopic technique may be technically limited by the ability to negotiate tortuous bends, particularly if the bowel is fixed. We used a through scope sphincterotome, which improved the ability to traverse difficult strictures. We have used the technique in four cases as a last resort. This resulted in a technical success in all four cases (100 percent). Sphincterotome is a useful adjunct in stenting difficult colorectal tumor strictures.

COLLAPSE‐SUBMERGENCE METHOD: SIMPLE COLONOSCOPIC TECHNIQUE COMBINING WATER INFUSION WITH COMPLETE AIR REMOVAL FROM THE RECTOSIGMOID COLON

Colonoscopy is a difficult examination to conduct for inexperienced examiners. In an attempt to improve the view, there is often a tendency to overinsufflate air, which causes elongation or acute angulations of the colon and makes passage of the scope difficult. Sakai et al. were the first to describe a simple colonoscopic technique using water infusion instead of air insufflation. We have modified this technique to simplify the procedure further by combining water infusion using disposable syringes with complete air suction from the rectum to the descending colon. With the resultant elimination of the boundary lines between water and air, a good view of the lumen is obtained though the transparent water. With the patient in the left lateral position, this procedure allows the water to flow straight down into the descending colon through the ‘collapsed’ lumen, and the scope to be easily negotiated through the straightened recto‐sigmoid colon and sigmoid‐descending colon junction with minimum discomfort. Measurements of the patients’ abdominal circumference during colonoscopy showed that colonic distension hardly occurred. Under supervision by the author, six complete novices were allowed to insert the colonoscope within 10 min by this method for one patient per week, as long as the patients did not complain of pain. The average trial number for the first cecal intubation within 10 min was 3.3, and the average success rate during the first 3 months was 58.6%. We believe that this ‘collapse‐submergence method’ is easy to master, even for inexperienced examiners.

Maximizing Detection of Adenomas and Cancers During Colonoscopy

Some patients who undergo colonoscopy that appeared to have cleared the colorectum of neoplasia return within a short interval (1-3 yr) with colorectal cancer. Although several a priori mechanisms could account for this occurrence, wide variation in detection rates of adenomas and cancer at colonoscopy suggests that suboptimal colonoscopic technique is a significant contributor. Optimal technique with white-light colonoscopy involves taking adequate time for inspection during withdrawal (an average of at least 6 min in normal colons), interrogating the proximal sides of folds, flexures, and valves, clearing fluid and debris, and distending adequately. Some adjunctive techniques are directed toward exposing more colonic mucosa during colonoscopy. Wide-angle colonoscopy appears to improve efficiency but does not eliminate miss rates. Colonoscopy in retroflexion was unsuccessful in reducing miss rates in one study, whereas cap-fitted colonoscopy was successful in reducing miss rates in one small study. Techniques to improve detection of flat lesions include pancolonic chromoendoscopy (CE). In two randomized controlled trials, CE improved adenoma detection, but CE does not appear to provide substantially greater yields than those obtained by the more sensitive white-light colonoscopists. Narrow band imaging and autofluorescence are being assessed for improved detection of flat lesions. Adenoma detection rates are an important measure of the quality of colonoscopy and should be reported to endoscopists in quality improvement programs in colonoscopy.

Prevalence and Characteristics of Flat and Depressed Colorectal Neoplasms in a Western Population: A Prospective Study by a Japanese Trained Endoscopist

Background: Flat and depressed colorectal neoplasms have been widely investigated in Japan and recently in Western countries with incidence rate of 6.8%-48.5%. This wide variation reflects differences in population characteristics or colonoscopic technique. The aim of this study was to determine the prevalence of flat neoplasms in a UK population by a colonoscopist trained in Japan. Methods: A prospective analysis of 1000 consecutive colonoscopies was performed. Macroscopically the lesions were classified according to the classification described by Japanese Society for Cancer of the Colon and Rectum and histological diagnosis was made based on WHO system. Result: Total colonoscopy (adjusted) was achieved in 98% of patients. Indications for colonoscopy were: neoplasia surveillance (211), change in bowel habit (179), bleeding (160), assessment of IBD (141), family history of colorectal neoplasms (106), anaemia (86), and others (117). In total 1075 polyps were found in 412 patients, which includes 25 cases of advanced cancer. 758 polyps were histologically proven to be neoplastic. Of these, 617 were classified as polypoid (81%) and 141 flat (IIa, IIb, IIc)(19%). A higher incidence of advanced pathology (severe dysplasia or Dukes'A adenocarcinoma) was observed in flat and depressed neoplasms (0% in IIa, 14% in IIb,IIc) than in polypoid ones (2%). Conclusion: A Japanese trained endoscopist found flat neoplasms represented 19 % of all adenomas (flat/depressed 3% in a western population. Flat elevated (IIa) and polypoid lesions appeared to have similar characteristics, while flat (IIb) or depressed lesions (IIc) contain more advanced pathology. Flat and depressed neoplasms are rare finding but exist in a Western population.

Comparison Between High-Resolution Colonoscopy with and Without Chromoendoscopy and Histological Findings in Diminutive Lesions of Rectosigmoid

Background: The ability to accurately differentiate adenomatous (AP) from nonadenomatous colonic polyps (non-AP) with the use of chromoendoscopy would obviate the need to remove all diminutive hyperplastic lesions (HP). The aim of the study was to define the accuracy of high-resolution chromoendoscopy for the determination of diminutive colonic polyp histology. Methods: In 112 patients refered for routine colonoscopy 193 polyps in the rectosigmoid and <5 mm in size were estimated for their histology. The endoscopists predicted the histopathology of each lesion based on its surface characteristics in two steps: using high-resolution colonoscopic technique without any staining and after dyeing with indigo carmine (ICD) according to the Kudo classification. Results: The resected polyps were comprised by 34 AP and 159 non-AP. When comparing histologically confirmed HPs to APs, prediction of HP based on endoscopic findings had a sensitivity of 92%, a specificity of 62%, a positive predictive value (PPV) of 91%, a negative predictive value (NPV) of 64%, and an overall accuracy of 79% (table 1). The corresponding sensitivity, specificity, PPV, NPV, and overall accuracy of prediction the histological diagnosis after ICD were 92%, 62%, 91%, 64%, and 80% respectively. Discussion: It is beyond doubt that the ICD enables the demarcation of flat and depressed lesions from normal colon mucosa. But our results suggest that the staining with ICD improves only marginally the determination between HP and AP using the high-resolution colonoscopes. The overall accuracy rate increased after dyeing from 79% to 80%. It confirms a great role of the high-resolution chromoendoscopy in distinguishing these two polyps types without any additional dyeing. The complete renunciation of histopathologic analysis cannot yet be achieved by chromoendoscopy.

Fifteen years later: colonoscopic retroflexion revisited.

Retroflex views of the rectal vault are included in the teaching of colonoscopic technique but are not pervasive in clinical practice. The utility of adding a retroflex maneuver at the end of colonoscopy has yet to be determined. The aim of this study was to evaluate the additional benefit of a retroflex view of the rectal vault at the completion of colonoscopic examination. A prospective study of consecutive colonoscopies performed by a single physician was conducted. The rectal vault was first visually inspected upon withdrawal of the colonoscope. The endoscope was then readvanced into the rectum and retroflexed to view the vault. Endoscopic findings on both views were recorded along with demographic patient information. The six groups of findings sought on the two views were: retained stool, abnormal hemorrhoids, erosions/ulcerations, polyps, masses, and normal examinations. A determination on whether retroflex views influenced patient diagnosis was recorded by the endoscopist. There were 453 patients enrolled: 182 (40.2%) male and 271 (59.8%) female, consisting of 216 African-Americans, 232 Caucasians, and five Asians. The retroflex maneuver was performed successfully in 445 of 453 patients. In all but nine cases, the retroflex view did not produce additional information. The nine findings included three inflammatory pseudopolyps, five hyperplastic polyps, and one case of erosions/ulcerations. In the majority of cases, retroflexing the endoscope does not produce additional information compared with the thorough examination in straight view. The retroflex view may be of benefit if there is suspicion of pathology upon insertion or withdrawal of the colonoscope.

Fifteen years later: colonoscopic retroflexion revisited

OBJECTIVE: Retroflex views of the rectal vault are included in the teaching of colonoscopic technique but are not pervasive in clinical practice. The utility of adding a retroflex maneuver at the end of colonoscopy has yet to be determined. The aim of this study was to evaluate the additional benefit of a retroflex view of the rectal vault at the completion of colonoscopic examination. METHODS: A prospective study of consecutive colonoscopies performed by a single physician was conducted. The rectal vault was first visually inspected upon withdrawal of the colonoscope. The endoscope was then readvanced into the rectum and retroflexed to view the vault. Endoscopic findings on both views were recorded along with demographic patient information. The six groups of findings sought on the two views were: retained stool, abnormal hemorrhoids, erosions/ulcerations, polyps, masses, and normal examinations. A determination on whether retroflex views influenced patient diagnosis was recorded by the endoscopist. RESULTS: There were 453 patients enrolled: 182 (40.2%) male and 271 (59.8%) female, consisting of 216 African-Americans, 232 Caucasians, and five Asians. The retroflex maneuver was performed successfully in 445 of 453 patients. In all but nine cases, the retroflex view did not produce additional information. The nine findings included three inflammatory pseudopolyps, five hyperplastic polyps, and one case of erosions/ulcerations. CONCLUSIONS: In the majority of cases, retroflexing the endoscope does not produce additional information compared with the thorough examination in straight view. The retroflex view may be of benefit if there is suspicion of pathology upon insertion or withdrawal of the colonoscope.

Colonoscopic indirect lymphangiography in a canine model.

Colorectal malignancies metastasize most frequently to mesenteric lymph nodes. Preoperative staging of these nodes by current modalities is problematic. This study evaluates the feasibility of indirect mesenteric lymphangiography as a colonoscopic technique in a canine model. Ten mongrel dogs underwent endoscopic submucosal injection of Ethiodol at various sites in the transverse, descending, and rectosigmoid areas. Serial abdominal roentgenograms were obtained up to 2 weeks postinjection. In seven of the animals, demonstration of mesenteric nodal uptake corresponding to the area(s) of injection was radiographically documented. In the remaining animals (early in the series) nodal opacification was inadequate. This lack of nodal uptake appeared to be due to nonsubmucosal contrast injection. No complications were noted. Colonoscopic indirect lymphangiography appears to be a safe and potentially useful modality in the evaluation of mesocolonic lymph nodes. Further studies to refine this technique and investigate its potential to preoperatively delineate abnormal nodal architecture are warranted.