Classic presentation of a child with pyloric stenosis is as follows
Age of presentation – commonest 4-6 weeks but range of a few days to five months.
Initially the baby feeds normally, but then develops vomiting, non-bilious in nature, increasing in frequency and force until ‘projectile’ vomiting.
Constipation and fewer wet nappies.
Jaundice in 10% (unconjugated) – resolves after surgery.
Haematemesis in 10% due to oesophagitis.
Metabolic changes in Pyloric Stenosis Significant vomiting induces a loss of chloride as well as hydrogen ions, this leads to hypochloraemic metabolic alkalosis.
Na+ re-absorption is one of the major functions of the kidney; Na+ is actively re-absorbed in preference to H+ and K+. The increased H+ loss results in acidic urine, an increased metabolic alkalosis and increased K+ loss (on top of the K+ loss due to vomiting). Hypokalaemia is not seen initially because of K+ shift from intracellular fluid to the ECF and dehydration. If K+ level are low before fluid replacement begins, then hypokalaemia will become worse if the rehydration fluid does not contain K+. Cardiac arrhythmias have occurred secondary to hypokalaemia in pyloric stenosis.
Pyloric stenosis Narrowing (stenosis) of the opening from the stomach to the first part of the small bowel (duodenum), due to enlargement (hypertrophy) of the pylorus.
Care of an Infant with Pyloric Stenosis
Referrals should be made when there is a confirmed diagnosis of pyloric stenosis. This is to avoid unnecessary transfers as far as possible. The diagnosis may be made clinically (strongly suspected on history with palpable pyloric mass) or with positive ultrasound.
Referral should be made to Southampton Children’s Hospital on-call paediatric surgical registrar (bleep 2798) or via switchboard out of hours
When diagnosis is confirmed the baby should be transferred as soon as there is a bed available. If there is a delay in bed availability please continue on IV fluids as per pathway until bed is available.
The baby will not have any surgery until the blood biochemistry is normalised.
Prior to transfer, all babies should:
Be made Nil By Mouth
Have a nasogastric tube (at least 8fr) inserted and left on free drainage
Have IV access established
Start IV fluids (see section - Fluid Regimen and Electrolyte Correction)
The STOPP tool (Safe Transfer of Paediatric Patient) must be completed before surgical referral to ensure a safe transfer process (available on the PIER website).
Insert a nasogastric tube (NGT) (following local guidelines)
On free drainage at all times
Plus two-hourly aspiration of the NGT
Fluid Regimen and Electrolyte Correction
Correct hypovolaemia: if the referring clinician considers that the infant has clinical signs of dehydration.
Rehydrate with 0.9% sodium chloride, using boluses of 10ml/kg.
Monitor central and peripheral capillary return (normal less than 2 seconds).
Serum bicarbonate >25 mmol/l - Use 0.9% sodium chloride + 5% Dextrose + 10 mmol potassium chloride per 500ml bag. Run at a rate of 150 ml/kg/day
Serum bicarbonate ≤ 25 mmol/l - Use 0.9% sodium chloride + 5% Dextrose + 10 mmol potassium chloride per 500ml bag. Run at a rate of 100 ml/kg/day
In infants less than 44 post-conceptual weeks, 10% dextrose may be required.
Replace NG losses
Every 1 ml of gastric losses must be replaced with 1 ml of either: