If you are suspecting a child to have Congenital Hypertrophic Pyloric Stenosis clinically. Next, the best investigation is?

ANSWER: (B) USGREF: Schwartz's 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 length)Double/triple track sign" = crowding of mucosal folds in pyloric channel"String sign" = passing of small barium streak through a pyloric channelTwining recess = "diamond sign" = transient triangular tentlike deft/niche 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 channel"Antral beaking" = mass Impression upon antrum with a streak of barium pointing toward the pyloric channelKirklin sign = "mushroom sign" = indentation of base of bulb (in 50%)Gastric distension with fluid"Caterpillar 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 854)"Target 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 mm)Pyloric volume >1.4 cm3"Cervix sign" = indentation of muscle mass on fluid-filled antrum on the longitudinal section"Antral nipple sign" = redundant pyloric channel mucosa protruding into gastric antrumExaggerated peristaltic wavesDelayed gastric emptying of fluid into the duodenum