Background: Hypertrophic pyloric stenosis (HPS) is a common cause of gastric outlet obstruction in young infants. Infants with HPS present with projectile vomiting, sometimes have electrolyte abnormalities and typically undergo pyloromyotomy to alleviate the obstruction. Abdominal US is the gold standard imaging study for diagnosis. Case reports of incidental hepatic portal venous gas have been reported in infants with HPS; however, no large studies have been conducted to determine the incidence or possible clinical implications of this finding.
Objective: To assess the incidence of portal venous gas in infants with HPS and to determine whether the presence of this gas in infants with HPS indicates a more unstable patient, increased length of stay or worse outcome.
Materials and methods: We conducted a retrospective review of sonographic reports containing "pyloric stenosis," excluding negative descriptor, at a tertiary-care children's hospital from November 2010 to September 2017. Data collected included pyloric thickness/length, liver evaluation, portal venous gas, any additional imaging, demographics, symptomatology days, electrolyte abnormality, and length of hospital stay.
Results: In a 7-year period, 545 US exams were positive for HPS. Of these, 334 exams included enough hepatic parenchyma to evaluate for portal venous gas. Infants in 6 of the 334 exams demonstrated portal venous gas (1.8%). Clinical presentation (length of symptoms and electrolyte abnormalities), demographics (male predominance and age at presentation) and imaging characteristics (pyloric thickness and length) were similar for the HPS groups with and without portal venous gas. There was no significant difference in outcome or length of hospital stay.
Conclusion: Visualization of portal venous gas in infants with HPS is not rare and appears benign, without need for further imaging. Portal venous gas in infants with HPS does not portend a more severe patient presentation or outcome.
Keywords: Hypertrophic pyloric stenosis; Infants; Outcome; Portal venous gas; Pylorus; Ultrasonography.