Sensitivity and cost minimization analysis of radiology versus olive palpation for the diagnosis of hypertrophic pyloric stenosis

Background/Purpose: Two strategies are commonly used for the initial diagnosis of hypertrophic pyloric stenosis (HPS): (1) physical examination and (2) radiologic evaluation using upper gastrointestinal series (UGI) or sonography. The authors wished to determine the sensitivity and relative cost of each strategy. Methods: The charts of 234 patients presenting over 3 years with a history suggestive of HPS were reviewed retrospectively. Cost, expressed as mean diagnostic charges (MDC) and mean total charges (MTC), was calculated according to two theoretical models. In model A, all patients first are examined by a surgeon. If an olive is palpable, they proceed to surgery. If not, they are sent to radiology. In model B, all patients have radiologic investigation first, and then surgical evaluation if the study result is positive. Results: Of the 234 patients, 150 had HPS (64%). Olives were appreciated in 111 of these (palpation sensitivity of 74%). There was one false-positive olive (0.7%) and no false-negatives. Sonography and UGI were equally accurate (sensitivity of 100%, 0.5% false-positive). Equations were generated to estimate MDC and MTC for our patient population under each model. In model A, MDC = $507 - ($221 x palpation sensitivity) and MTC = $2,543 - ($240 x palpation sensitivity). In model B, MDC = $449 and MTC = $2,454, and costs were independent of ability to feel an olive. When cost was plotted against palpation sensitivity, model A yielded a lower MDC than model B if palpation sensitivity was at least 26%, and a lower MTC if palpation sensitivity was at least 37%. Because our palpation sensitivity was 74%, approximately $100 per patient would be saved by sending all infants suspected of having HPS to a surgeon for examination as an initial step. Conclusions: Although highly sensitive, imaging is superfluous if an olive is palpable. Children suspected of having HPS should have a surgical consultation before a radiology study as long as the surgeon's palpation sensitivity for an olive is at least 37%. Improved palpation skills will result in maximum financial savings.