complications were adverse drug reaction, abdominal pain, or nausea andvomiting.Results:

Surveillance Colonoscopies ByHigh and Low Risk

Patient Group

MajorComplications at

SurveillanceColonoscopy

MinorComplications at

SurveillanceColonoscopy

n Rate/1000 n Rate/1000

All Patients N5 1699 3 (1.8) 10 (5.9)High Risk N5 532 1 (1.9) 6 (11.3)Low Risk N5 1167 2 (1.7) 4 (3.4)

Complications were few but occurred in both the low and high risk groups.

Conclusions:Elimination of 6-year surveillance for the lower risk patientswho constitute 68% of the cohort could improve the benefit/harm ratio ofsurveillance following colonoscopic polypectomy. Supported in part byNCI CA-268652 and the Tavel-Reznik Fund.

475

Retrospective analysis of missed polyps and adenomas oncolonoscopy at Dayton Veteran Affairs Medical CenterIhab Shehadeh, M.D., Srilakshmi Rebala, M.D., Rakesh Kumar, M.D.,Ronald J. Markert, Ph.D., Christopher J. Barde, M.D., N. Gopalswamy,M.D., FACG. Department of Gastroenterology, Veterans AffairsMedical Center/Wright State University, Dayton, OH.

Purposeof this study is to evaluate the miss rates for advanced adenomasat Dayton VA Medical Center.Methods: Using the computer generated reports, we reviewed patients withpolyps, who had repeat colonoscopic examinations at Dayton VA MedicalCenter from July 1, 1992 to June 30, 1999. Patients with incompletecolonoscopies and those with colonoscopies repeated at intervals greaterthan 36 months were excluded. Advanced adenomas were defined asadenomas with size equal to or greater than 10 mm or with high-gradedysplasia or carcinoma. A total of 235 patients meeting above criteria wereincluded in this study.Results:

Missed polyps

<5 mm 61 >10 mm Total

Polyps 327 36 5 368Adenoma 223 30 3 256Non-adenoma 104 6 2 112

Though smaller polyps were missed very frequently, the miss rate foradvanced adenomas on repeat colonoscopy was low (0.81%). Only 2(0.85%) patients in this study had three missed advanced adenomas.

Conclusions:The miss rate for advanced adenomas on repeat colonosco-pies is less than those reported in previous studies and the percentage ofpatients affected by this missed rate is very low.

476

Expression of human defensin-5 in dysplastic polypoid lesions of thegutB Shen, MD, J Dumot, DO, J-P Achkar, MD, A Ormsby, MD, BLashner, MD, FACG, A Brzezinski, MD, FACG, D Ghosh, PhD, CBevins, MD, FACG. The Cleveland Clinic Foundation, Cleveland, OH.

Altered intestinal differentiation is characteristic of metaplastic, dysplastic,and neoplastic lesions throughout the gastrointestinal (GI) tract. Distin-guishing non-dysplastic from dysplastic polyps is important but sometimesdifficult with routine histopathology. Human defensin-5 (HD5), an antimi-

crobial peptide produced by Paneth cell of the intestinal crypt may be auseful marker of intestinal cell differentiation in the histological evaluationof GI pathology.Aim: To study HD5 phenotypic expression in nondysplastic and dysplasticpolypoid lesions in the GI tract.Methods: Biopsy or polypectomy specimens of fundic gland polyps,gastric adenoma, duodenal adenoma, small bowel (SB) hamartomas, co-lonic hyperplastic polyps (HP), and adenomas of the colon were studied byHD5 immunohistochemistry using a monoclonal antibody.Results:HD5 immunoreactivity was present in none of the 14 cases (0%)with nondysplastic lesions in GI tract, but it was present in 16 of the 18cases (88.9%) with dysplastic lesions [adenomas of stomach (66.7%),duodenum (100%), and colon (87.5%)] (Table). In the majority of cases,HD5 immunoreactivity was localized to both epithelial and glandularportions of the dysplastic lesions. There was significant difference in HD5immunoreactivity between nondysplastic and dysplastic lesions (P, 0.05).Conclusion: Expression of HD5 is observed in the majority of dysplasticpolypoid lesions but not in nondysplastic lesions, suggesting this markermay be useful to detect dysplastic epithelium in equivocal cases. Futurestudies on flat adenomas or dysplasia-associated lesions or masses arewarranted.

Nondysplastic Lesions Dysplastic Lesions

Fundicpolyps

SBhamartoma

ColonHP

Gastricadenoma

Duodenumadenoma

Colonadenoma

N 5 3 6 3 7 8HD51 0 0 0 2 7 7

477

Hollow viscus wall thickening on abdominal CT: What does itmean?Sanjeeb Shrestha, Nyingi Kemmer, Harbans Singh, Pankaj J Pasricha,Gurinder Luthra*. University of Texas Medical Branch, Galveston,Texas, United States.

Purpose: Although abnormal thickening of the wall of the esophagus,stomach, or colon is often reported on abdominal computer tomographyscan (CT), the pathological and/or clinical significance of this findingremains to be established. The aim of this study was to determine ifabnormal CT scan results accurately predict GI tract pathology by corre-lating with endoscopic or surgical findings.Methods: Patients with abnormal thickening of the stomach or colon onabdominal CT were identified during a three year period between July 1996to June 1999. Significance was ascribed to any pathological lesion (foundeither surgically or endoscopically) if it caused a change in patient man-agement.Results:Of a total of 67 patients, 40 patients had correlative pathologicaldata available. The most common indication for the CT was abdominal pain(50 %).

Other significant lesions found in the colon included ischemic bowel (1),duodenal, cecal and appendicular perforation (1 each), inflammatory boweldisease (4), polyp (1), radiation colitis (1) and diverticulitis (1). Although5 patients (30%) with stomach wall thickening had gastritis, this was notconsidered significant. Among the four patients with gastric cancer, the CTfindings were diffuse thickening of stomach wall in two patients, nodularthickening of anterior gastric wall in one patient and 6 cms mass in thecardia with liver metastasis in the last patient. In all patients with significantlesions, there was a 100% concordance between the site of CT abnormalityand site of endoscopic abnormality.Conclusions: CT appearance of thickened hollow viscus organs is asso-ciated with significant disease, particularly in the colon. There was asurprisingly high incidence of cancer in both the lower and upper GI tract.Thus the finding of a “thickened wall” on CT should lead to promptendoscopy of the involved organ.

2550 Abstracts AJG – Vol. 95, No. 9, 2000