Pyloric stenosis.PDF

Prepared By Hend Wageh Abozed  Introduction/Definition Pyloric stenosis is a narrowing of the pylorus, the opening from the stomach into the small intestine. Pyloric stenosis is rare in infants older than age 3 months. It occurs most often in infants younger than 6 months. It i...

Prepared By Hend Wageh Abozed  Introduction/Definition Pyloric stenosis is a narrowing of the pylorus, the opening from the stomach into the small intestine. Pyloric stenosis is rare in infants older than age 3 months. It occurs most often in infants younger than 6 months. It is more common in boys (especially firstborn male child) than in girls. Male: Female = 4:1 3/1000 live birth Most common cause for laparotomy before 1 year. The cause is idiopathic / unknown. Premature birth: Pyloric stenosis is more common in babies born prematurely than in full-term babies.  Pathophysiology Normally, food passes easily from the stomach into the first part of the small intestine through a valve called the pylorus. With pyloric stenosis, the muscles of the pylorus are stenosed and thickened. Due to enlargement (hypertrophy) of the muscle surrounding this opening (the pylorus, meaning "gate"), which spasms when the stomach empties. This prevents the stomach from emptying into the small intestine. The gastric outlet obstruction due to the hypertrophic pylorus impairs emptying of gastric contents into the duodenum. As a consequence, all ingested food and gastric secretions can only exit via vomiting, which can be of a projectile nature.  Pathophysiology Persistent vomiting results in loss of stomach acid (hydrochloric acid). The chloride loss results in a low blood chloride level which impairs the kidney's ability to excrete bicarbonate. This is the significant factor that prevents correction of the alkalosis. A secondary hyperaldosteronism develops due to the decreased blood volume. The high aldosterone levels cause the kidneys to retain Na+ (to correct the intravascular volume depletion), and excrete increased amounts of K+ into the urine (resulting in a low blood level of potassium). The body's compensatory response to the metabolic alkalosis is hypoventilation resulting in an elevated arterial pCO2.  Clinical presentation Vomiting is the first symptom in most infants. Vomiting (non-bilious) is forceful (projectile vomiting). Vomiting usually starts around 3 weeks of age, but may start any time between 1 week and 5 months of age. Vomiting may occur after every feeding or only after some feedings. Vomiting might be mild at first and gradually become more severe as the pylorus opening narrows. The vomit may sometimes contain blood. The infant is hungry after vomiting and wants to feed again.  Clinical presentation Wave-like motion that ripple across baby's upper abdomen (from the left to the right in the upper abdomen) soon after feeding, but before vomiting. This is caused by stomach muscles trying to force food through the narrowed pylorus. Failure to gain weight or weight loss Constant hunger Burping Abdominal pain Changes in bowel movements. Since pyloric stenosis prevents food from reaching the intestines, babies with this condition might be constipated.  Clinical presentation Other symptoms appear several weeks after birth and may include: Signs of dehydration, such as dry skin and mouth, less tearing when crying, or become lethargic and dry diapers. Olive-shaped mass when feeling the upper abdomen, which is the abnormal pylorus swollen belly. The thickened pylorus is felt classically in the middle upper part or right upper quadrant of the infant's abdomen (at angle between right rectus muscle and liver).  Diagnostic evaluation Physical examination. History taking. Ultrasound of the abdomen may be the first imaging test. Blood tests -- often reveals an electrolyte imbalance. Barium x-ray -- reveals a swollen stomach and narrowed pylorus. (Narrowed, elongated pyloric channel with pyloric mass effect on stomach and duodenum, String sign). String sign  Treatment The definitive treatment of pyloric stenosis is surgical pyloromyotomy known as Ramstedt's procedure (dividing the muscle of the pylorus to open up the gastric outlet).