<prompt> If you are suspecting a child to have Congenital Hypertrophic Pyloric Stenosis clinically. Next, the best investigation is?Barium mealUSGCTMRI  <response>: ANSWER: B USGREF: Schwartzs 9th ed chapter 39, Sabiston Surgery, 18th edition, Page 2058,2059See details of Congenital hypertrophic pyloric stenosis in Surgery 2007See PLATER-38 KEY PLATER-38 KEYHYPERTROPHIC PYLORIC STENOSISContrast study:Elongation narrowing of the pyloric canal 2-4 cm in lengthDoubletriple track sign crowding of mucosal folds in pyloric channelString sign passing of small barium streak through a pyloric channelTwining recess diamond sign transient triangular tentlike deftniche in the midportion of the pyloric canal with the apex pointing inferiorly secondary to mucosal bulging between two separated hypertrophied muscle bundles on the greater curvature side within pyloric channelAntral beaking mass Impression upon antrum with a streak of barium pointing toward the pyloric channelKirklin sign mushroom sign indentation of base of bulb in 50Gastric distension with fluidCaterpillar sign gastric hyperperistaltic wavesUSG:Palpation of the pyloric tumor also called the olive in the epigastrium or right upper quadrant by a skilled examiner is pathognomonic for the diagnosis of HPS. If the olive is palpated, no additional diagnostic testing is necessary1.When the olive cannot be palpated, the diagnosis of HPS can be made with an ultrasound exam or fluoroscopic UGI series.USG has now replaced barium meal as the first-line investigation in an infant with nonbilious vomiting to whomHPS is suspected Sutton 7th ed vol 1 page 854Target sign hypoechoic ring of hypertrophied pyloric muscle around echogenic mucosa centrally on the cross-sectionElongated pylorus with thickened muscle: Elongated pyloric canal 16 mm in length, Pyloric muscle wall thickness 3.5 mm some books says 4 mmPyloric volume 1.4 cm3Cervix sign indentation of muscle mass on fluid-filled antrum on the longitudinal sectionAntral nipple sign redundant pyloric channel mucosa protruding into gastric antrumExaggerated peristaltic wavesDelayed gastric emptying of fluid into the duodenum 