Dehydration - Pyloric Stenosis

I've probably missed something, but PAP7 seems very similar to dehydration in children. The new bit is pyloric stenosis, also known as hypertrophic pyloric stenosis, which we'll cover here.

Cause
There is hypertrophy and hyperplasia of the two muscular layers of the pylorus. This labels the gastric atrum. The pyloric canal becomes lengthened and the whole pylorus becomes thickened. The stomach may then become markedly dilated.

Associations
First-born white males
Northern European ancestry
Family history (7%)
Bottle feeding
Macrolide antibiotics for infants

Presentation
Pyloric stenosis normally starts in the first 3 weeks of life.
Non-bilious vomiting or regurgitation - projectile in 70% of cases.
The infant is still hungry after feeding and may be jaundiced.
Signs of dehydration and malnutrition.
Firm,non-tender and mobile hard pylorus 1-2cm in the RUQ. Best palpated when vomited and calm. Happens in 60-80%.

Investigations
Bloods:  Severe metabolic alkalosis with partial respiratory compensation
    Hypokalemia

    Hypochloremia
    Hyponatraemic, hypokalaemia --> or maybe higher because of dehydration
Alkaline Urine
AXR: Distended stomach with minimal distal intestinal bowel gas
USS:  Pylorus hypertrophy

Management
NG Tube if vomiting
Fluid resuscitation
Correct electrolyte abnormalities
Nil by mouth
Surgeons for a pyloromyotomy - splitting muscle layer of the pylorus

References
http://us.bestpractice.bmj.com/best-practice/monograph/680.html
http://lifeinthefastlane.com/ccc/pyloric-stenosis/
http://radiopaedia.org/articles/pyloric-stenosis
http://prehospitalmed.com/2013/02/18/levitans-no-desat-with-nasal-cannula-for-infants-with-pyloric-stenosis-requiring-intubation/
http://lifeinthefastlane.com/tag/pyloric-stenosis/
http://pemlit.org/2013/04/13/12th-april-2013-electrolyte-profile-of-paediatric-patients-with-hypertrophic-pyloric-stenosis/
http://emedicine.medscape.com/article/803489-overview
http://www.rcemlearning.co.uk/modules/my-baby-is-throwing-up-and-its-getting-me-down/4
https://www.rcemlearning.co.uk/curriculum/paeds-acute/pap7/

http://broomedocs.com/2013/02/clinical-case-079-is-it-pyloric-stenosis/ may be useful - their server is still down so I haven't read it yet!