D i.e. High gastric residuesUltrasonography is the investigation of choice to confirm diagnose of hyperophic pyloric stenosis with accuracy > 95% (approching almost 100%)Q. USG visualizes thickened and elongated pyloric canalQ. USG criteria for diagnosis include >16 mm pyloric length and >4mm pyloric muscle wall thicknessQ. Gastric residues are low b/o recurrent emesisQ.The hyperophied muscle project into gastric antrum. There is a constant assocaition with hyperplasia of antral mucosa.- It is a common developmental condition (3 in 1000 live bihs), affecting boys more than girls (M:F = 4/5 :1)Q. There is a familial predisposition.Affected infant usually presents between 2-6 weeks of age, with projectile non bilious vomiting (D/D include pylorospasm, hiatus hernia & preampullary duodenal stenosis). HPS is never seen beyond 3 months of age except in premature infants in whom enteral feeding has been staed late.- Despite the recurrent vomiting, child has a voracious appetite that leads to cycle of feeding & vomiting that invariably results in severe dehydration, hypochloremichypokalemic metabolic alkalosis with eventual decrease in urine PHDiagnosis can be made clinically on the basis of history and palpation of an olive mass in the subhepatic region (right upper quadrant) and presence of visible gastric (antral peristaltic) wavesQ.Diagnosis of the HPS can be established (confirmed) by either USG (method of choice)Q or barium study.Pyloric signs includeString sign, is passing of thin barium streak through narrowed & elongated pyloric canal. It is most specific sign.Pyloric canal is almost always curved upward posteriorlyDouble/triple track sign or double string sign is produced by barium caught between crowded mucosal folds in pyloric canal overlying the hyperophied muscle & parallel lines may be seen.Diamond sign or twining recess is transient triangular tent like cleft/niche in midpoion of pyloric canal with apex pointing inferiorly secondary to mucosl bulging between two seperated hyperophied muscles on the greater curvature side of pyloric canal.Apple core lesion, pyloric segment looks like apple core with under cutting of distal antral & proximal duodenal bulb.Antral signs includePyloric teat sign is out pouching along lesser curvature b/o disruption of antral peristalsis.Shoulder sign is impression of hyperophied muscle on distended gastric antrum.Antral beaking is noted as thick muscle narrows the barium column as it enters the pyloric canal.Olive pit sign is impression of pyloric muscle upon antrum seen as tiny amount of barium at orifice.Caterpillar sign is gastric hyperperistaltic waves.Kirklin mushroom sign is indentation of base of duodenal bulb.Ultrasonography (USG)It is the method of choice to directly visualize the HPS. The examination is typically performed with a high frequency linear transducer (>5MH2) (as the pylorus & duodenum are very superficial in an infant) with infant in right posterior oblique position (to move any fluid present in fundus into antral & pylorus region. The stomach should not be emptied prior to examination as this makes identification of antropyloric area difficult. If fluid is administered to make visualization better, it should be removed at the end of examination to prevent vomiting/aspiration. Features include)Doughnut appearance/Bull's eye or target sign is hypoechoic (black) ring of hyperophied pyloric muscle around echogenic (reflective) mucosa & submucosa on cross /transverse section images.Shoulder/cervix-sign is indentation of hyperophied muscle on fluid filled gastric antrum on longitudinal section.Antral nipple sign is protrusion (evagination) of redundant pyloric mucosa into distended antrum.Double tract sign refers to fluid trapped in center of elongated pyloric canal is seen as two sonolucent streaks in center.Exaggerated peristattic waves & delayed gastric emptying of fluid into duodenumElongated pylorus with thickened muscles (most specific) is indicated by Length > 15mm, muscle thickness >3mm and transverse serosa to serosa diameter >15mm is consistent with HPS. At least 2 values should be positive. A thickness pylorospasm is transient & mostly resolve in 30 minutes and there is considerable variation in measurement or image appearance with time during thickness. (GI imaging) Pyloric canal length 16-17min, muscle wall thickness 2 3-3.2mmQ, pyloric volume > 1.4cm3, pyloric transverse diameter 13mm with pyloric canal closed and length (mm) + 3.64x + 3.64 x thickness (mm) >25 (Wolfgang) Pyloric length >16mm & muscle thickness > 4mm (Swaz)