Purpose or Case Report: To evaluate false positive rate of community hospital ultrasound (US) diagnosis of hypertrophic pyloric stenosis (HPS)
Methods & Materials: Our institutional review board approved this HIPAA-compliant study; informed consent was waived. We identified all patients (1/2015-12/2016) who performed US for newly diagnosed HPS at an outside hospital (OSH), referred to our children’s hospital. Only positive studies were included.
Confidence of OSH diagnosis was grouped based on key words as follows: high confidence (compatible, positive, diagnostic of, consistent with, meet criteria for, highly suspicious), low (favor, concern, suspicious, suggesting, may represent), or equivocal (equivocal, non-diagnostic, borderline). OSH imaging and reports for discrepant cases were reviewed by a pediatric radiologist to determine reasons for false diagnosis.
Surgical results were used as the gold standard for positive HPS, while the gold standard for negative HPS utilized was successful non operative management with no readmission for surgery on follow-up chart review.
Results: 65 cases were referred from OSHs to our children’s hospital. 6/65 (9.2%) were equivocal for HPS and 59 (90.8) positively identified HPS. Of the 59 cases that identified HPS, 30 (50.8%) did so with high confidence and 29 (49.2%) with low. 11/59 (18.6%) of cases diagnosed with HPS at OSH were not found to be HPS on further evaluation at our institution. Of discrepant cases 2/11 (18.2%) were diagnosed with high confidence by OSH and 9/11 (81.8%) low confidence. The most common 7/11 (%) reason for false positive results was misinterpretation of pylorospasm as HPS.
In 13/59 (22.0%) the US were repeated in our children’s hospital as the OSH study was considered technically limited.
Conclusions: US for evaluation of HPS performed by non-pediatric radiologist is a limited study. About half of the positive studies were read with low confidence and 18% of the studies were false positives.