4 Overview of the GI tract Stomachhollow muscular organ.second phase of digestion, following mastication.highly acidic environment due to gastric acid production and secretionpH range usually between 1 and 4, depending onfood intake, time of the day, drug use, and other factors.Combined with digestive enzymes, able to break down large molecules to smaller ones so that they can eventually be absorbed from the small intestine.
5 Overview of the GI tract Stomachproduces and secretes about 2 to 3 liters of gastric acid per day (highest in the evening).Absorption of vitamin B12 from the small intestine is dependent on conjugation to a glycoprotein called intrinsic factor which is produced by parietal cells of the stomach.
7 Overview of the GI tract Deuodenalhollow jointed tube (25-30 cm) connecting the stomach to the jejunum.first and shortest part of the small intestine and it is where most chemical digestion takes place.begins with the duodenal bulb and ends at the ligament of Treitz.largely responsible for the breakdown of food in the small intestine.Brunner's glands, which secrete mucus, are found in the duodenum.
8 Overview of the GI tract DeuodenalRegulates the rate of emptying of the stomach via hormonal pathways.Secretin and cholecystokinin are released from cells in the duodenal epithelium in response to acidic and fatty stimuli present there when the pyloris opens and releases gastric chyme into the duodenum for further digestion. These cause the liver and gall bladder to release bile, and the pancreas to release bicarbonate and digestive enzymes such as trypsin, lipase and amylase into the duodenum as they are needed.
10 Overview of the GI tract Jejunalcentral of the three divisions of the small intestine (between duodenum and ileum).small intestine is usually between 5.5-6m long in adults (2.5m is the jejunum).pH in the jejunum is usually between 7 and 8 (neutral or slightly alkaline).specialized lining for the absorption of carbohydrates and amino acids (proteins broken down in the stomach by pepsin and acid).
11 Overview of the GI tract Jejunalcarbohydrates are broken down in the duodenum by enzymes from the pancreas and liver into sugars.Fats are broken down in the duodenum by "lipase" from the pancreas into fatty acids.Amino acid, sugar, fatty acid particles, vitamins, minerals, electrolytes and water are small enough to soak into the villi of the jejunum and drop into the blood stream.
12 Overview of the GI tract Ileumlast portion of the small intestine (responsible for absorption of fats, and bile salts).pores in the ileum are slightly bigger than those in the jejunum and allow vitamin B12, vitamins dissolved in fatty liquids, electrolytes, bile salts and water to be reabsorbed.ileum joins the colon at the ileocecal valve (prevents the back flow of materials into the small intestine).
13 Overview of the GI tract Colon.Its function is to move the waste from the small intestine on to the rectum.material first passes through the ascending colon and then through the transverse colon absorbing more water and potassium.The sigmoid colon is designed to slow down this movement of the waste until it is ready to be eliminated.
14 Types of defectsopen abd wall (all or some of the abdominal contents noted outside the infant)closed abd wall (normal appearance outside the infant)
15 Open abdominal wall defects gastroschisisomphalocele
16 GastroschisisFull-thickness defect of the abd wall exposing intestinal contents.Generally a small defect (3-6 cm).Right lateral to the umbilicus.1 in 40,000 births.Male> femaleInfants are generally preterm or SGAMalrotation affects nearly all infantsSurvival rates are higher than omphalocele, 95%
17 Gastroschisis Treatment involves Gastric decompression Gut rest AntibioticsSilo suspension (sealed plastic device surgically attached to infant and suspended above infant.allows the bowel to return to normal size.commonly have underdeveloped abd capacity thus not allowing for primary closure.Daily decompression allow for stretching of the abd tissue and minimizes intestinal damage.Primary closure- generally for small defects or those term infants with adequate abd tissue.
19 Omphalocelefailure of the intestines to return from the umbilical cord into the abd cavity resulting in a transparent membrane that encapsulates intestinal tissue.1 in 5,500 birthsMale > femaleFrequently associated (50% - 77%) with other syndromes such as trisomies, CHD, CDHRanges from 2-15 cm on average. Smaller defects may be overlookedLarger defects may include spleen and liver also
20 Omphalocele Survival rates are high (75% - 95%). Due to associative chromosomal issues, surgery is the second choice of treatment. First line treatment involves abdominal wrapping or painting the defect with silver nitrate or silvadine to promote eschar formation and epitheal tissue growth.Abd decompression and delayed feedings are important to allow the inflamed intestinal lumen to return to normal size. Antibiotics may also be used.Surgical repair is generally reserved for the most severe cases and involves using gortex flaps to cover the transparent sack.An unfortunate result of non-surgical closure is malrotation.
24 Bilary Atresiascomplete obstruction of the bile flow of the extrahepatic ducts.Most common form of ductal cholestasis1 in 10,000 birthsPrevents bile from entering the duodenumCause unknown (malformed or inflammatory process)Digestion and absorption of fat soluble vitamins (A,D,E,K) is impaired.Leads to cirrhosis symptoms and death if untreated.Associated congenital defects found in 15% (CHD, Splenic issues, small bowel atresias, trisomies)
25 Bilary Atresias Normal appearing infant with normal stools Symptoms usually begin with persistent jaundice after the first week of lifeDirect bili levels begin to climbGreen bronze color to skinGradually stools become clay-coloredDifferential diagnosis (hepatitis, HIV, CMV, HSV errors of metabolism)Survival untreated is less than 2 yrs.Nearly all pts have long term liver issues (elevated enzymes [ALT, AST, GGT, CRP], chronic fatigue, poor weight gain, ascites)Treatment involves hepatic portoenterostomy (Kasai procedure) which is the dissection and resection of the extrahepatic duct.
27 Duodenal Atresia Incomplete recanalization of the lumen. Transverse diaphragm of the tissue completely obstructing the lumen1 in 7,500 births.25% of all duodenal atresias are related to DownsPolyhydramnios is the #1 first sign on prenatal US60-70% of DA pts also have trisomies, Imperf A, TE anomilies, CHD, VATER, VACTERL, renal issues, annular pancreasBilious Emesis is the #1 presenting symptom after delivery
28 Duodenal AtresiaProximal atresias/obstruction generally results in vomiting within the first few hours of life.Distal atresias/obstruction results in emesis longer after delivery.Classic double bubble on xray. Gasless pattern after the atresias65%-84% survival rate with early intervention.Treatment involves decompression of the stomach by continuous suctioning followed by surgical removal of the atresia area with a side to side anastomosis.
31 Jejunoileal Atresiaobstruction of the distal segment of the small intestine.Most commonly near the ileo-cecal valve1 in 20,000 birthsPolyhydramnios is not as common of a risk factor (only ¼ of the presenting infants).Classic “triple bubble” and microcolon on xray84%-95% survival rate.Treatment involves decompression of the stomach by continuous suctioning followed by surgical removal of the atresia area with a side to side or end to end anastomosis
34 Stenosis Far less common than atresias/obstructions. Generally from excessively narrow areas of the small intestine (duodenum or the ileo-cecal valve).Most common cause is by webbed areas of the inner lumen.Occurs most often following other GI surgeries
35 TE fistula and/or EAFailure of the trachea to differentiate from the esophagusThere are different types of disorder85% have EA and a TE fistula8% have EA without any connection to the trachea1% have esophageal fistula and no connection to the stomach4% are an H type fistula1 in 4,500 births
36 TE fistula and/or EA VATER and VACERL association is common 20%-30% are pretermSigns are excessive oral secretions (from an inability to swallow), inability to pass OG/NG tubes, aspiration, chronic pneumonias.97% survival ratesMortality is associated with associative disordersSurgery depends on the type of disorder.
39 NEC Necrosis of the mucosal and submucosal layer of intestine. Any portion of the GI tract can be affected.Causes are still a debate (most common causes are selective bowel ischemia, infection or delayed/improper feedings.Osmolarity of certain formulas/meds increase risk of NEC.Feeding of EBM decreases the risk of NEC by 65% in the preterm infant.Most common disease affecting hospitalized infants, 8% of all inpatient infants.
40 NEC 65%-92% of infants affected with NEC are preterm infants. Most commonly seen in infants 3-21 days post delivery.Xray shows tiny lucent bubbles.Generally infants present with abd distention, increased emesis, bloody stools or feeding intolerance.Treatment involves 3 basic principles:Bowel rest—NPO for daysPrevention of progressive injury—NPO, Fluid management, antibioticsPlacement of abd drains.
42 PerforationSpontaneous rupture of the intestine/colon allowing for leakage of air into the abd cavity.Most commonly associated with NEC and ischemic bowelMost common risk factors are NEC, sepsis, mechanical ventilation, prematurity, long term steroid usage and postoperative abd complications.Survival is directly related to how quickly the staff is able to identify clinical changes.Pneumoperitoneum (free air in the abd cavity) is the most common radiographic sign of perforation (football or sail sign in the most lateral abd on a left lateral decub).
43 Perforation INTESTINAL PERFORATION IS AN EMERGENCY!!!! Surgical removal of the damaged and perforated area is almost always required.Treatment also involves preventing additional bowel injury by:Bowel rest—NPO for daysGastric decompressionFluid management, antibioticsPlacement of abd drains may not be needed.
46 Diaphragmatic herniaHerniation of intestinal contents into the thoracic cavity resulting in underdeveloped lung tissue leading to respiratory distress.1 in 4,000 birthsUsually present with cyanosis, respiratory distress and scaphoid abd.Usually seen during routine prenatal US.
47 Diaphragmatic herniaPost delivery xray reveals intestinal loops in the chest cavityImmediate intubation and gastric decompression is essential to higher survival rates.Treatment also involves surgical placement of abd tissue back into abd cavity once the infant has become stable.
49 Hirshprungs Also known as megacolon or aganglionic colon Congenital absence of ganglionic cells in the distal colon and rectum.Failure of the neural crest cells to migrate properly to caudal region.Local failure of the colon to relax thus causing a restrictive, narrowed area.Zone between the ganglionic and the tapered aganglionic area of the distal colon is called the transitional zone.The rectum is always involved.1 in 5,000 births.Males > females
50 Hirshprungs Most infants are chromosomally normal Primary symptoms are bilious vomiting, failure to pass stools and abdominal distention. All infant should pass first stool within 48 hrs of birth.A significantly dilated colon proximal to the transitional zone on xray.Survival rates are high at 80%-95% with early interventionDiagnosis is only definitive by performing a rectal biopsyTreatment involves a standard rectal “pull trough” which involves a complete removal of the affected aganglionic zone, allowing for 7-10 days of bowel rest and slow reintroduction of feeds.
51 Imperforate anusThe abnormal or incomplete partitioning of the cloacae resulting in anal stenosis or atresia.Rectourethral and rectovaginal fistulas are common.Cause is unknown1 in 5,000 births20% - 75% have associated anomalies.VATER and VACTERAL syndromes are common
52 Imperforate anus Atresias are the most obvious types. Stenosis is less obvious and usually present as stooling from the penis/vagina or meconium stained urine.Spinal anomalies occur in 50% of patients.Overall mortality (20%) depends on the type if defect and the associated anomalies.Treatment for stenotic anal openings involves daily progressive dilation of the anus.For more involved complete atresia, surgical opening and pull through is essential.
54 Meconium plug syndrome Intestinal obstruction of the lower distal colon and rectumMost commonly associated with decreased colonic motility and hyptonicity (CF).Different from hirschprungs (no aganglionic cell regions).Risk factors include prematurity, diabetic mothers, neurologically devastated infants and mothers treated with magnesium sulfate.
55 Meconium plug syndrome Primary symptoms are bilious vomiting, failure to pass stools and abdominal distention.Mortality is very low once the stool is passed.Surgical intervention is rare.Small saline enemas are the preferred treatment.
57 Meconium ileusObstruction of the distal colon due to abnormally thick meconiumGenerally a result of meconium plug syndrome.95% of the infants with meconium ileus have CF.1 in 2,000 birthsPrimary symptoms are progressive abdominal distention within the first hours of life followed by bilious vomiting and a failure to pass stools.
58 Meconium ileusOn xray the infant will have dilation proximal to the obstruction and a soap-bubble appearance at the point of obstruction (due to the trapped air in the dense meconium).Non operative therapy is generally successful in 15%-25% of infants and involves regular hyperosmolar enemas to evacuate the thickened stool. Medication therapy also should be implemented.A temporary ostomy to decompress the obstructed area may be necessary until fluid status is stabilized.