The contrast enema for Hirschsprung disease: predictors of a false-positive result.

OBJECTIVE

To examine predictors of a false-positive (FP) result on contrast enema (CE) for the diagnosis of Hirschsprung disease (HD).

METHODS

Retrospective analysis, over a 5-year period (1999-2004), of infants (<6 months of age) with suspected HD undergoing rectal biopsy following abnormalities identified on CE (transition zone [TZ], abnormal rectosigmoid ratio, microcolon, retained contrast, or mucosal irregularity).

RESULTS

One hundred twenty-nine patients underwent rectal biopsy following an abnormal CE. The FP rate was 48.5% (66 with HD). Age below 30 days (OR, 3.4; 95% CI, 1.1-10.3), female sex (OR, 3.4; 95% CI, 1.6-7.3), and absence of TZ (OR, 6.3; 95% CI, 2.6-15.3) were independently associated with an increased risk for FP on multiple variable logistic regression. A history of bilious emesis decreased the probability of FP (OR, 0.2; 95% CI, 0.06-0.5).

CONCLUSIONS

Transition zone, sex, age, and bilious emesis are important predictors of FP in those with suspected HD and CE abnormalities. With 100% incidence of FP, infants younger than 30 days with neither bilious emesis nor a TZ and female infants younger than 30 days with these features may represent a subpopulation in whom rectal biopsy can be avoided.