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Question 2#

Which of the following is most consistent with pyloric stenosis?

a. Na l40 Cl 110 K 4.2 HCO3 26
b. Na 142 Cl 90 K 5.2 HCO3 39
c. Na 140 Cl 95 K 4.0 HCO3 18
d. Na 139 Cl 85 K 3.2 HCO3 36

Correct Answer is D


Infants with hypertrophic pyloric stenosis (HPS) develop a hypochloremic, hypokalemic metabolic alkalosis. The urine pH level is high initially, but eventually drops because hydrogen ions are preferentially exchanged for sodium ions in the distal tubule of the kidney as the hypochloremia becomes severe (paradoxical aciduria). The diagnosis of pyloric stenosis usually can be made on physical examination by palpation of the typical "olive" in the right upper quadrant and the presence of visible gastric waves on the abdomen. When the olive cannot be palpated, ultrasound (US) can diagnose the condition accurately in 95% of patients. Criteria for US diagnosis include a channel length of over 16 mm and pyloric thickness over 4 mm.