Congenital Defects of the Bowel

Question 1

Describe the anatomy of the most common type of tracheo-esophageal atresia

Answer 1

85%:

• upper esophagus ends in blind pouch,
• lower esophagus attached to trachea

Question 2

Tracheoesophageal fistula:

associated with what other congenital anomalies?

Answer 2

20% assoc with VACTERL:

Vertebral

Anorectal

Cardiac

TEF

Renal

Limb

Question 3

Tracheoesophageal fistula

-clinical presentation for dx (4)

Answer 3

1. prenatal polyhydramnios
2. excessive salivation (‘mucousy’ baby)
3. feeding intolerance
4. failure to pass NG/OG tube

Question 4

Physiologic Jaundice in newborns

-why? mechanisms (3)

Answer 4

1. decreased RBC half life of newborns
2. Newborn liver has lower ability to conjugate bilirubin
3. reduced enterohepatic circulation

Question 5

Neonatal Jaundice is abnormal when:

1. jaundice lasts beyond ? age
2. direct bilirubin >?
3. (term) total bilirubin > ?
4. (preterm) total bilirubin > ?

Answer 5

1. beyond 2-3 weeks old
2. >2mg/dL
3. >12 mg/dL
4. >14 mg/dL

Question 6

Neonatal Bile Duct obstruction

-what are the 2 main causes?

Answer 6

1. BIliary atresia
2. choledochal cyst

Question 7

Biliary atresia

• when do babies typically present?
• presenting symptoms (3)

Answer 7

• typical presentation 4-6 weeks old
  1. Jaundice
  2. ahcolic, pale stool (no bile in gut)
  3. Dark urine (bilirubinemia)

Question 8

Biliary atresia

-what’s abnormal on blood test?

Answer 8

-conjugated hyperbilirubinemia

Question 9

Biliary atresia

• describe natural progression of disease
• life expectancy w/o tx

Answer 9

1. Progressive obliteration of extrahepatic biliary sructures
2. by 12 weeks–cholestasis, neocholangiogenesis, hepatocellular injury
3. eventually: cirrhosis, portal HTN, end stage liver disease

Death <2 years old. Require Kasai procedure and/or transplanation

Question 10

Biliary atresia

• etiology
• genetic inheritance?

Answer 10

• unknown, but likely an in utero biliary epithelial injury that leads to inflammation.
• possible infectious and toxic stimuli
• probably not genetic

Question 11

Biliary atresia

-what do you see on liver biopsy, and what’s happening?

Answer 11

Neocholangiogenesis (bile duct proliferation)

• multiple bile ducts try to proliferate inside liver, but lack of bile ducts leading out of liver, so liver is damaged by bile back pressure.
• use CK19 stain to visualize
• eventually: cirrhosis (you see bridging fibrosis)

Question 12

Biliary atresia

• describe surgical tx
• Prognosis after surgery (3 groups)

Answer 12

Kasai procedure (hepatoportoenterostomy):

1. Cut small intestine and attach distal end to liver at the porta hepatis (where the common hepatic duct emerges) to allow gut entry of bile
2. Connect the remaining end of intestine back into distal intestine (forming a ‘Y’)

Prognosis:

1/3 good long term result

1/3 progressiv liver disease

1/3 short term failure (need liver transplant)

Question 13

Biliary atresia

-give what to patients after Kasai procedure? (3)

Answer 13

1. DEAK vitamin supplementation (malabsorption of fat soluble)
2. ursodexycholic acid
3. ampicillin prophylaxis for cholangitis

Question 14

Jaundiced infant, with elevated direct bilirubin.

what’s your differential? (3)

Answer 14

1. cholelithiasis/choledocholithiasis
2. bile plug syndrome
3. choledochal cyst

other unlikely: infection, tumors

Question 15

Choledochal cysts

-what congenital anatomic variant is much more common in people with a choledochal cyst, and why?

Answer 15

-Long common channel for common bile duct and pancreatic duct.

A distal blockage can lead to pancreatic enzymes flowing up the common bile duct and causing cyst formation.

Question 16

Choledochal cysts

-most feared complication

Answer 16

-Biliary adenocarcinoma (2.5-15% incidence)

Question 17

Choledochal cysts

• most common symptoms for pts >1 year old: (3)
• late complications

Answer 17

1. pain
2. intermittent jaundice
3. mass
4. cirrhosis, portal HTN
5. biliary adenocarcinoma

Question 18

Choledochal cysts

1. best test to dx
2. most common tx

Answer 18

1. Ultrasound
2. Remove bile duct/cyst, attach intestine directly to liver

(hepaticojejunostomy, hepaticoduodenostomy)

Question 19

You see an infant vomiting yellow/green material.

Think what?

Answer 19

Bilious emesis is a surgical emergency!

Question 20

Malrotation of gut:

-what is the normal embryologic process, and what happens with malrotation?

Answer 20

1. normal: GI tract rotates 270 degrees counterclockwise
2. malrotation: Gut twists on itself, causing volvulus–lack of mesenteric blood flow means twisted gut segment can die

Question 21

What are Ladd bands, and what’s their danger?

Answer 21

Ladd bands: fibrous peritoneal tissue that connects cecum to abdominal wall.

In malrotation, Ladd bands cross the duodenum and can cause duodenal obstruction

Question 22

Malrotation of gut:

• How to dx?
• describe surgical tx

Answer 22

Imaging: use Xray with barium swallow.

If ligament of Treitz (duodenojejunal junction) is right of spine, suspect malrotation

-Ladd’s procedure: untwist bowel, cut Ladd’s bands

Question 23

Duodenal atresia

clinical presentation (3)

Answer 23

1. polyhydramnios in utero (no swallowing of amniotic fluid)
2. ‘double bubble’ sign
3. bilious vomiting

Question 24

Duodenal atresia

-assoc with what other congenital problem(s)?

Answer 24

• Down’s syndrome
• also other cardiac, genitourinary, anorectal abnormalities

Question 25

Jejunoileal Atresia - pathogenesis - what are 2 possible causes?

Answer 25

- in utero vascular disruption leads to ischemic necrosis of fetal intestine. Gaps in intestine result. 1. Inherited thrombophilia--spontaneous clots may cause ischemia to gut 2. maternal use of vasoconstrictive meds--eg pseudoephedrine, cocaine, nicotine

Question 26

Duodenal atresia: - pathogenesis - during what weeks?

Answer 26

- In utero, duodenaum passes through a solid phase, then lumen opens during weeks 8-10 - insult during that time can result in duodenal atresia

Question 27

Meckel's diverticulum -is this a 'true' diverticulum? why?

Answer 27

- Yes, b/c it contains all 4 layers of the bowel wall: 1. mucosa 2. submucosa 3. muscularis propria 4. serosa

Question 28

Meckel's diverticulum -pathogenesis

Answer 28

-failure of the vitelline duct to involute. Vitelline duct connects GI lumen with yolk sac in utero

Question 29

Meckel's diverticulum -rule of 2's (5)

Answer 29

1. occurs in 2% of population 2. 2 types of abnormal lining (stomach and pancreas) 3. located within 2 feet of ileocecal valve 4. 2 inches in length 5. symptoms by age 2

Question 30

Meckel's diverticulum -symptoms: (3)

Answer 30

1. bleeding 2. blockage of intestine 3. inflammation most cases are asymptomatic

Question 31

Hirschsprung's disease - pathogenesis - associated with what congential problem(s)?

Answer 31

- failure of neural crest cells to migrate to colon wall to form enteric nervous system. The segment of colon w/o neural cells lacks both Meissner's and Auerbac's plexuses. - Loss of motility at the junction between normal and aganglionic segments. - assoc with Down's syndrome

Question 32

Hirschsprung's disease -specific genetic mutation

Answer 32

RET mutations are most common. RET is a receptor tyrosine kinase that transduces growth/differentation signals.

Question 33

Hirschsprung's disease -what invasive test to dx?

Answer 33

Suction Rectal biopsy -special biopsy that takes all layers of gut wall to search for ganglion cells

Question 34

Hirschsprung's disease -clinical presentation (3)

Answer 34

typically newborn: 1. failure to pass meconium 2. bilious emesis 3. enterocolitis (life threatening)

Question 35

Necrotizing enterocolitis - classic presentation - classic population

Answer 35

-classically a premature infant presents a few weeks after birth with abdominal distention and increased difficulty breathing

Question 36

Necrotizing enterocolitis -what are 3 significant factors in its pathogenesis?

Answer 36

1. prematurity 2. dysbiosis (alteration of normal gut flora) 3. formula feeding (you should feed infant human milk)

Question 37

Necrotizing enterocolitis -clinical presentation (6)

Answer 37

1. abdominal distention 2. feeding intolerance/emesis 3. rectal bleeding 4. abdominal wall erythema 5. temp instability/apnea/bradycardia 6. pneumatosis on xray (gas cysts in bowel wall)

Question 38

Necrotizing enterocolitis -list stages of disease and their characteristic symptoms

Answer 38

Stage 1: feeding intolerance Stage 2: pneumatosis intestinalis (gas cysts in colon wall) Stage 3: ascites, perforation, peritonitis

Question 39

Necrotizing enterocolitis - mortality rate - after tx, there is increased risk of what? (3)

Answer 39

- mortality 20-30% - Increased risk of: 1. short gut syndrome (after removing bowel) 2. neurodevelopmental delay 3. bronchopulmonary dysplasia

Question 40

Anorectal malformation -associated with what congenital disorders? (2)

Answer 40

1. Down's 2. VACTERL complex vertebral, anorectal, cardiac, TEF, renal, limb

Question 41

VACTERL association

Answer 41

vertebral anorectal cardiac TEF esophageal atresia renal limb

Question 42

Anorectal malformation - pathogenesis - how do males and females typically present differently?

Answer 42

- abnormal descent of urorectum--hindgut fails to descend to anus. - males: more common "high" malformations--rectovesicular or rectourethral fistulas - females: more common "low" malformations to perineum/vestibule. Or anteriorly displaced anus

Question 43

Anorectal malformation -symptoms after surgical treatment

Answer 43

100% will have periodic constipation. Anorectal region is missing the nerves that make rectum relax in response to rectal distention.