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1. What is the aetiology of congenital hypertrophic pyloric stenosis?
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The aetiology of the pyloric muscle 'tumour' in pyloric obstruction in infants is unknown. It may result from an abnormality of the ganglion cells of the myenteric cells; failure of the sphincter to relax may then produce an intense work hypertrophy of the adjacent circular pyloric muscle.
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2. Does congenital hypertrophic pyloric stenosis run in families?
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It is a familial condition.
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3. What percentage of cases of congenital hypertrophic pyloric stenosis occur in the first born?
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Fifty per cent of cases occur in the first born and the condition often occurs in siblings.
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4. After what age is it extremely uncommon for an infant to develop congenital hypertrophic pyloric stenosis?
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After 12 weeks of age it is extremely uncommon.
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5. How does an infant with congenital hypertrophic pyloric stenosis present? What are the clinical features of this condition?
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The presenting symptom is projectile vomiting. The vomit does not contain bile and the child takes food avidly immediately after vomiting, i.e. he or she is always hungry. There is a failure to gain weight and, as a result of dehydration, the baby is constipated (the stools resembling the faecal pellets of a rabbit). The infant may be dehydrated and visible peristalsis of the dilated stomach may be seen in the epigastrium. Ninety-five per cent have a palpable pyloric tumour, which is felt as a firm 'bobbin' in the right upper abdomen, especially after vomiting a feed.
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6. What are the differential diagnoses for congenital hypertrophic pyloric stenosis?
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(1) Intracranial birth injury. (2) Neonatal intestinal obstruction: from duodenal atresia, volvulus neonatorum or intestinal atresia, the symptoms commence within 1–2 days of birth and the vomit contains bile. (3) Enteritis: diarrhoea accompanies this. (4) Overfeeding: here, there are no other features to suggest pyloric stenosis apart from vomiting.
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7. What special investigations would you use to investigate congenital hypertrophic pyloric stenosis?
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(1) Ultrasound. (2) Abdominal X-ray. (3) Barium meal.
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8. Why is ultrasound used to investigate congenital hypertrophic pyloric stenosis?
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Correct answer:
Ultrasound scan demonstrates the thickened pylorus and large stomach.
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9. Why is abdominal X-ray used to investigate congenital hypertrophic pyloric stenosis?
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Correct answer:
This reveals a dilated stomach with minimal gas in the bowel, in contrast to dilated coils of bowel in intestinal obstruction.
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10. Why is a barium meal used to investigate congenital hypertrophic pyloric stenosis?
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Correct answer:
This reveals the pyloric obstruction with characteristic shouldering of the pyloric antrum due to the impression made on it by the hypertrophied pyloric muscle. However, this investigation is rarely called for.
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11. How would you treat congenital hypertrophic pyloric stenosis?
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Correct answer:
This is anomalous in that the more seriously ill the child, the less urgent the operation. With prolonged vomiting the infant becomes dehydrated with a hypochloraemic metabolic alkalosis. In such cases a day or two must be spent in gastric lavage and fluid replacement (saline with added potassium chloride), by either the subcutaneous or intravenous route. The otherwise healthy child can be submitted to operation soon after admission. The surgical treatment is Ramstedt’s pyloromyotomy. A longitudinal incision is made through the hypertrophied muscle of the pylorus down to the mucosa and the cut edges are separated. The infant is given glucose water 3 hours after the operation and this is followed by 3 hourly milk feeds, which are steadily increased in amount. Results are excellent and the mortality is extremely low.
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12. What would the acid–base state of a baby with congenital hypertrophic pyloric stenosis be like?
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He or she would have a hypochloraemic metabolic alkalosis.
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13. What is the surgical treatment for congenital hypertrophic pyloric stenosis? What is the prognosis?
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Correct answer:
Ramstedt’s pyloromyotomy. A longitudinal incision is made through the hypertrophied muscle and the cut edges are separated. The infant is given glucose water 3 hours after the operation and this is followed by 3 hourly milk feeds, which are steadily increased in amount. Results are excellent and the mortality is extremely low.
