Pyloric stenosis is a current condition in pediatric surgery. The medical management prior to surgery consists of ionic correction. The nasogastric tube is commonly used to prevent gastric fluid inhalation before surgery, but there is no study on it benefits in this specific use. Other studies suggest that utilization of a gastric tube in pyloric stenosis may increase the duration of the medical treatment. The aim of the study is to evaluate the benefit of the nasogastric tube to prevent respiratory complications. This retrospective, monocentric and descriptive study include all patients hospitalized for pyloric stenosis in the university hospital in Amiens between 2014 and 2021. Patients with and without nasogastric tube prior to surgery are compared, regarding respiratory complications define as use of antibiotic, or oxygen therapy or infection in the lungs X-ray before surgery. The investigators analyze pre-operative data: vomiting, dehydration, time to ionic disorders correction and pain, and also notice the length of hospital stay. Data during hospitalization are analyzed and will be noticed the last medical contact represent by the post-operative consultation.

Inclusion Criteria:

• all patients with hypertrophic pyloric stenosis

Exclusion Criteria:

• refusal of data collection and use from patient's parent or family

all patients hospitalized for pyloric stenosis in the university hospital in Amiens between 2014 and 2021