SAQ 191 – Paediatrics – pyloric stenosis with hypochloraemic alkalosis

A 3-week-old boy presents with frequent vomiting over 24 hours. Arterial blood gas, serum biochemistry, and urine biochemistry are shown below.

Test	Result	Reference range
FiO2	0.21
pH	7.54	7.35-7.45
pCO2	50 mmHg	35-45
pO2	62 mmHg	80-95
Bicarbonate (ABG)	41 mmol/L	22-28
Base excess	+10	-3 to +3
O2 saturation	99%	>95
Sodium	131 mmol/L	134-146
Potassium	2.1 mmol/L	3.4-5.0
Chloride	66 mmol/L	98-106
Bicarbonate (serum)	45 mmol/L	22-28
Urea	10.5 mmol/L	2.5-6.4
Creatinine	0.05 mmol/L	0.05-0.1
Glucose	3.4 mmol/L	3.5-5.5
Urine sodium	22 mmol/L
Urine potassium	28 mmol/L
Urine chloride	<10 mmol/L

Provide one (1) calculation that assists interpretation of these results.

(Marked out of 1.0)

/ 1

State the significance of the calculated finding.

(Marked out of 1.0)

/ 1

State the most likely diagnosis.

(Marked out of 1.0)

/ 1

List four (4) findings from these results that support the diagnosis.

(Marked out of 4.0)

/ 4

Complete the table with two (2) urgent key investigations and one justification for each.

(Marked out of 4.0)

Investigation	Justification
1.
2.

/ 4

Total Score: 0 / 11

Percentage: 0%