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Correction of Pyloric and Duodenal Stenosis
Narrowing of the pylorus or duodenum

Stenosis (narrowing) of the pylorus or duodenum may occur in infants resulting in obstruction of the stomach or duodenum to the passage of food.

Pyloric Stenosis

Anatomy

  • The stomach is arbitrarily divided into three parts (Figure 1):
    1. The cardia is the part of the stomach that is adjacent to the esophagus
    2. The body of the stomach is the largest part and has two curvatures, the lesser curvature, which lies on the inside of the C, and the greater curvature, which lies on the outside of the C
    3. The pylorus is the part of the stomach that lies at the end of the stomach and is demarcated from the body by a difference in the type of glands from those in the body. The pyloric canal is the narrow segment of the pylorus that approaches the pyloric sphincter
  • The wall of the stomach is divided into four layers
    1. The mucosa is the inner layer and contains the glands that produce the gastric juice
    2. The submucosa is a thin layer lying just beneath the mucosa
    3. The muscularis is the muscle layer that has an inner circular portion and an outer layer that runs the length of the stomach
    4. The serosa is the outer layer of the stomach
Figure 1 - Sectional anatomy of the pylorus showing the stomach, pylorus and duodenum. © P. Montelone

Pathology

  • Following birth there is progressive hypertrophy (thickening) of the muscle layers of the pylorus
  • The hypertrophic muscle causes narrowing of the pyloric canal (Figure 2)
  • This narrowing causes an obstructive process preventing passage of stomach contents into the duodenum resulting in frequent vomiting
  • The cause is unknown
Figure 2 - Thickening of the muscle layer of the pyloric sphincter causes obstruction of the pylorus. © P. Montelone

History and Exam

  • Pyloric stenosis is usually not present at birth with symptoms beginning at 3-6 weeks of age
  • It occurs in about 3 in1000 live births and is more common in whites with a male to female ratio of 4:1
  • Associated congenital defects are more common in infants with pyloric stenosis. There is a higher familial incidence when either parent had pyloric stenosis
  • These infants typically have non bilious (no bile) vomiting around 3-5 weeks of age. The vomiting is frequently described as projectile
  • The infants will invariably want to feed after vomiting
  • They will not gain weight and also show signs of dehydration
  • Examination may reveal a palpable "olive" like mass (hyperetrophied pyloric musculature) in the upper right abdomen
  • The infants usually show poor skin turgor (wrinkly skin consistency) due to dehydration

Tests

  • The diagnosis may readily be made by:
    1. Ultrasound examination of the abdomen shows dilation of the stomach
    2. X-ray following the swallowing of a barium containing fluid shows narrowing of the pylorus (string sign)
  • Due to repeated vomiting, these infants may show the electrolyte imbalance of:
    1. Hypokalemia - low serum potassium
    2. Hyperchloremia - elevated serum chloride
    3. Alkalosis - increased serum alkalinity due to elevated serum bicarbonate

Indications for Surgery

  • The obstruction has to be relieved surgically when the child is adequately hydrated and electrolyte imbalance restored
  • Surgery does not have to be done as an emergency

Surgery

  • Surgery is performed under general anesthesia with monitoring in a warmed operating room
  • The operation is known as the Fredet-Ramstedt procedure (pyloric myotomy):
    1. An incision is made in the right upper quadrant of the abdomen (below the ribs, Figure 3)
    2. The abdomen is explored to rule out other anomalies
    3. The pylorus is held firmly and an incision is made through hypertrophied muscle (myotomy, Figure 4)
    4. The muscle is bluntly separated with a hemostat (Figures 5 and 6). This allows the mucosa to herniated through the myotomy to open up the pyloric canal (Figure 7)
Figure 3 - Incision in the right upper quadrant of the abdomen for the Fredet-Ramstedt procedure. © P. Montelone
Figure 4 - The thickened pylorus is grasped and an incision is made in the pylorus through the muscle layer leaving the mucosa untouched. © P. MonteloneFigure 5 - After the muscle is cut it is spread to show the mucosa. © P. Montelone
Figure 6 - The muscle is further spread until the mucosa is allowed to bulge out. © P. MonteloneFigure 7 - Cross-section through the pylorus showing how the mucosa bulges outward to relieve the stenosis. © P. Montelone

Complications

  • The complications associated with any major operation may occur
  • Bleeding
  • Infection
  • Respiratory distress (difficulty breathing)
  • Hypothermia (low body temperature)
  • Low urine output
  • Bowel obstruction
  • Possible leak at the myotomy site (fistula)

Post Operative and After Care

  • Care is provided in a Pediatric Intensive Care Unit
  • Breathing, body temperature and urine output are monitored
  • Intravenous fluids are given until the infant can eat
  • A tube is placed through the nose into the stomach to decompress the stomach
  • These infants can usually be started on dilute formula feedings 6-8 hours after surgery and progress rapidly to full strength formula

After Care

  • These children are usually hospitalized for only a brief period
  • At discharge, they should be eating, drinking and having bowel movements
  • There is follow up with the surgeon and pediatrician

Duodenal Stenosis

Anatomy

  • The duodenum is the first part of the small bowel and connects the stomach to the jejunum, which is the second part of the small bowel (Figure 8)
  • The duodenum is retroperitoneal (has peritoneum, the thin layer of tissue that lines the abdominal cavity) only on the anterior (front) side, It is fixed in location and wraps around the head, neck and body of the pancreas
  • It is divided into four parts:
    1. The first part joins the stomach
    2. The ampulla of Vater (entrance site into duodenum of the joined common bile duct and pancreatic duct) enters the medial (towards the midline) side of the second part of the duodenum. The accessory pancreatic duct enters slightly higher in the medial wall of the duodenum
    3. The superior mesenteric artery and vein (major blood vessels for the bowel) pass anterior to the third part
    4. The fourth part joins the jejunum
  • The ligament of Treitz (a supporting band of peritoneum and muscle fibers) marks the point between the duodenum and jejunum
Figure 8 - Anatomy of the stomach, duodenum, pancreas and jejunum. See text. © C. McKee

Pathology

  • Duodenal stenosis is an uncommon cause of intestinal obstruction in the newborn. It is more common in adulthood as a result of peptic ulcer disease
  • Duodenal stenosis may be caused by compression of the surface of the duodenum by Ladd's bands secondary to incomplete rotation of the bowel (Figure 9)
  • Annular pancreas enveloping the duodenum may result in duodenal stenosis or obstruction (Figure 10)
Figure 9 - The duodenum is compressed by peritoneal (Ladd's) bands secondary to incomplete rotation of the bowel. © P. MonteloneFigure 10 - Annular pancreas surrounding the duodenum and causing stenosis. © C. McKee

History and Exam

  • The appearance of symptoms is related to the degree of duodenal obstruction
  • Symptoms frequently do not develop in the newborn period
  • Typically the child has intermittent nausea with vomiting. The vomitus contains bile
  • The child fails to thrive
  • There are no specific abdominal findings associated with these incomplete obstructions

Tests

Several studies make the diagnosis of duodenal stenosis:

  • Plain x-rays may show an enlarged stomach with retained stomach contents, the fisrt part of the duodenum may be dilated
  • X-ray following the swallowing of a barium containing fluid shows shows duodenal obstruction
  • Upper Gastrointestinal Endoscopy (flexible fiberoptic scope examination) will show a duodenal obstruction (See Panendoscopy)

Indications for Surgery

  • Indications are dictated by the degree of intestinal obstruction
  • A high-grade obstruction is usually done at the discretion of the surgeon (elective surgical intervention)
  • Low-grade partial obstructions may go many years without requiring surgery
  • Most operations take place in the adult years with an occasional operation in childhood

Surgery

  • Surgery is performed under general anesthesia
  • An incision is made in the upper abdominal
  • The stenosis is usually bypassed without removing any pancreatic or duodenal tissue. The various bypass procedures are:
    1. Duodenoduodenostomy - a hole is made in the side of the duodenum above and below the stenosis followed by suturing the walls of the duodenum at the holes together to form the bypass (side to side bypass)
    2. Duodenojejunostomy - end to side bypass of duodenum to jejunum (Figure 11)
    3. Gastrojejunostomy - side of the lower stomach to the side of the jejunum bypass (Figure 12)
    4. Gastroduodenostomy - side of the lower stomach to side of the duodenum bypass
Figure 11 - End to side bypass of duodenum to jejunum (duodenojejunostomy). © P. MonteloneFigure 12 - An obstruction of the duodenum can be bypassed by a stomach to jejunum anastomosis. © C. McKee

Complications

  • The complications associated with any major operation may occur
  • Bleeding
  • Infection
  • Respiratory distress (difficulty breathing)
  • Hypothermia (low body temperature)
  • Low urine output
  • Bowel obstruction
  • Fistula - leak at suture line

Post Operative and After Care

  • Same as for pyloric stenosis