investigations
Last reviewed 01/2018
The diagnosis of pyloric stenosis is based on the history and examination and positive findings on a barium meal swallow. In infantile pyloric stenosis, a barium meal will show delayed gastric emptying, a dilated stomach and a narrowed and attenuated pyloric canal - the 'string sign'.
Other diagnostic tests include the test feed, where the baby is given a drink, sat on the mother's lap, and the hand dipped deeply under the liver to feel the pyloric tumour.
Investigations important for resuscitation include:
- urea and electrolytes, with blood gas - the classic finding is of a hypokalaemic, hypochloraemic metabolic alkalosis
- urinary pH may be measured
Other investigations include ultrasound; however, this is very operator-dependent. In good hands pyloric stenosis is diagnosed when muscle thickness is 4 mm or more.