Sonographic diagnosis of infantile hypertrophic pyloric stenosis: critical appraisal of reliability and diagnostic criteria.

Critical review of the current medical literature shows lack of complete evaluation of the parameters of "medical decision making" in the sonographic diagnosis of infantile hypertrophic pyloric stenosis (IHPS). A computer program was specially written to calculate these parameters on three published series of patients with IHPS, using originally advocated and modified sonographic criteria. The sensitivity and specificity of the sonographic tests are influenced by the chosen diagnostic criteria, while predictive values are affected by the prevalence of IHPS in the particular population studied. A change in the ventral-dorsal diameter criterion from 1.2 cm to 1.5 cm increased the sensitivity (from 0.52 to 0.97, p less than 0.0001) and negative predictive value (0.60 to 0.95, p less than 0.01) in the population of Wilson et al (9), changing the prevalence of IHPS from 0.58 to 0.12, (sensitivity, specificity and sonographic criterion kept constant) reduced the positive predictive value from 0.90 to 0.48 (p less than 0.0001). The term "accuracy" has little scientific meaning and should be discarded in comparative evaluation. These results indicate that the real contribution of sonography in decision making in patients with suspected IHPS (but without a palpable mass) has not been properly evaluated by research workers.