Pyloric Stenosis Flashcards
Define pyloric stenosis.
Hypertrophy and hyperplasia of pyloric sphincter muscle causing gastric outflow obstruction. Also called infantile hyerptrophic pyloric stenosis (IHPS).
Explain the aetiology of pyloric stenosis.
Multifactorial; both hereditary and environmental factors are involved. Identical twins have 87% concordance.
Theories include deficiency of neurones containing nitric oxide synthase, abnormal myenteric plexus innervations, infantile hypergastrinaemia, exposure to macrolide antibiotics and persisting duodenal hyperacidity.
What are risk factors for pyloric stenosis?
30% are first-born males.
Male sex (M:F = 4:1).
7% Family history (parental).
More common with Caucasian infants.
What is the pathophysiology of pyloric stenosis?
Marked hypertrophy and hyperplasia of the two (circular and longitudinal) muscular layers of the pylorus occurs, leading to narrowing of the gastric antrum.
The pyloric canal becomes lengthened and the whole pylorus becomes thickened. The mucosa usually is oedematous and thickened. In advanced cases, the stomach is markedly dilated.
Summarise the epidemiology of pyloric stenosis?
1-2/500 live births.
History: Usually presents at 2-6/52 (up to 6/12). 95% of patients between 2-12/52.
What are the presenting symptoms of pyloric stenosis?
Progressive non-billous vomiting within 30 minutes of a feed; may become projectile. Occasionally associated with coffee-ground vomiting secondary to gastritis or Mallory-Weiss tear at the gastro-oesophageal junction.
Persistently hungry following projectile vomiting.
Constipation.
Failure to thrive.
What are the signs of pyloric stenosis?
Systemic: Weight loss +/- signs of dehydration, increased capillary refill time (CRT), decrease skin turgor, sunken fontanelle, decreased urinary output, may be jaundiced (5%).
Gastrointestinal: Visible peristalsis from left-to-right upper quadrant during a feed. An ‘olive-sized’ pyloric mass deep in the right upper quadrant palpated during a feed or more likely immediately after a vomit. The palpation of the pyloric tumour can be aided by the use of a test feed (usually perfomed via an NGT).
What are appropriate investigations for pyloric stenosis?
Bloods: U&Es for hypochloraemic hypokalaemic alkalosis secondary to vomiting: Decreased K+/Cl-/Na+, Increased HCO3-/Urea, +ve vase excess and may have mild, unconjugated hyperbilirubinaemia.
USS abdomen: Can be used to aid diagnosis. Surgeon’s choice comared to clinical examination. A pyloric muscle diameter > 3-4 mm and pyloric channel > 18 mm in length are considered diagnostic.
What is the preoperative management for pyloric stenosis?
Fluid resuscitation and correction of electrolyte imbalance.
Requires extra IV fluids to correct the deficit caused by dehydration with potassium correction.
Important that the electrolyte imblances are correct prior to an anesthetic (due to respiratory complications).
What is the surgical management for pyloric stenosis?
Operation: Ramstedt pyloromyotomy; a longitudinal incision through the serosa with blunt splitting of sphincter muscles at the pylorus without incising the pyloric mucosa.
Operative approach: Traditionally access to the pylorus was through a right upper quadrant incision. The operation is now performed routinely via a supraumbilical incision for cosmetic reasons and some centres are also performing the pyloromyotomy via a laproscopic approach.
What are the complications of pyloric stenosis?
Recurrence is uncommon.
Gastric or duodenal perforation can occur intraoperatively althought morbidity <1%.
What is the prognosis of pyloric stenosis?
Excellent post-surgery.
Initial postoperative vomiting common but settles within 24-48 hours.
