Introduction: Previously undiagnosed colonic ulcers lack characterization
regarding epidemiology, symptomatology, clinicopathological correlation and
clinical outcome.
Aim: To define the epidemiology and the role of endoscopy in the approach to
de novo colonic ulcers.
Methods: A review of all the patients with unexpected ulcerated lesions
diagnosed during total colonoscopy in 1995 was carried out. Patients with
erosions, flat or apthoid colonic ulcers, with biopsy, and without primary
diagnosis were included. Histology and clinical outcomes were reevaluated a year
later. Correlation of these findings with those on endoscopy was evaluated by
McNemar chi-square. Also, prior and posterior probabilities for each disease
were evaluated using Bayes' rule, in a decision analysis setting.
Results: We found 198 patients who met study criteria. Twenty-one (11%) had
an ulcerated mass, 6 (3%) and ulcerated polyp, and 171 (86%) "simple"
ulcer. The first two groups had confirmed histologic diagnosis in all cases; the
latter group comprises the sample of our study. The predominant symptom was:
hematochezia, 66 (38%); diarrhea, 42 (25%); abdominal pain, 44 (26%); anemia, 12
(7%). Multiple ulcers were found in 34 (20%) of the patients. The diagnostic
probabilities, using Bayes' rule are:
A-Diag B-Prior prob (%) C-Pathol/Clin(%) Post prob (%)
Crohn's 30 21 51.4
Ulc. colitis 25 11 22.4
Undeterm. 20 6 9.8
Infectious 9 11 8.1
Ischemic 2 12 2.0
Malignancy 9 7 5.1
After correlating endoscopic, clinical, and pathologic findings:
Diagnosis Endosc. Clin/Path. Coincidental p
Crohn's 49 35 29 0.006
Ulc. colitis 40 18 16 0.000
Undeterm. 33 9 6 0.000
Infectious 15 18 12 0.31
Ischemic 3 19 3 0.000
Malignancy 14 11 10 0.18
Conclusion: Endoscopic diagnoses of malignancy and infection in de novo
ulcers of the colon is accurate. Crohn's, Ulcerative colitis and ischemia ulcers
are difficult to diagnose by endoscopc observations alone. Bayes' rule allows
identification of expected probabilities of disease, and should be based on
local incidence rates. This type of analysis is simple, and straightforward, and
is the basis for further clinical decision analysis.
