Correct answer:

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.