Congenital Defects of the Bowel Flashcards
Describe the anatomy of the most common type of tracheo-esophageal atresia
85%:
- upper esophagus ends in blind pouch,
- lower esophagus attached to trachea
Tracheoesophageal fistula:
associated with what other congenital anomalies?
20% assoc with VACTERL:
Vertebral
Anorectal
Cardiac
TEF
Renal
Limb
Tracheoesophageal fistula
-clinical presentation for dx (4)
- prenatal polyhydramnios
- excessive salivation (‘mucousy’ baby)
- feeding intolerance
- failure to pass NG/OG tube
Physiologic Jaundice in newborns
-why? mechanisms (3)
- decreased RBC half life of newborns
- Newborn liver has lower ability to conjugate bilirubin
- reduced enterohepatic circulation
Neonatal Jaundice is abnormal when:
- jaundice lasts beyond ? age
- direct bilirubin >?
- (term) total bilirubin > ?
- (preterm) total bilirubin > ?
- beyond 2-3 weeks old
- >2mg/dL
- >12 mg/dL
- >14 mg/dL
Neonatal Bile Duct obstruction
-what are the 2 main causes?
- BIliary atresia
- choledochal cyst
Biliary atresia
- when do babies typically present?
- presenting symptoms (3)
- typical presentation 4-6 weeks old
1. Jaundice
2. ahcolic, pale stool (no bile in gut)
3. Dark urine (bilirubinemia)
Biliary atresia
-what’s abnormal on blood test?
-conjugated hyperbilirubinemia
Biliary atresia
- describe natural progression of disease
- life expectancy w/o tx
- Progressive obliteration of extrahepatic biliary sructures
- by 12 weeks–cholestasis, neocholangiogenesis, hepatocellular injury
- eventually: cirrhosis, portal HTN, end stage liver disease
Death <2 years old. Require Kasai procedure and/or transplanation
Biliary atresia
- etiology
- genetic inheritance?
- unknown, but likely an in utero biliary epithelial injury that leads to inflammation.
- possible infectious and toxic stimuli
- probably not genetic
Biliary atresia
-what do you see on liver biopsy, and what’s happening?
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)
Biliary atresia
- describe surgical tx
- Prognosis after surgery (3 groups)
Kasai procedure (hepatoportoenterostomy):
- 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
- 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)
Biliary atresia
-give what to patients after Kasai procedure? (3)
- DEAK vitamin supplementation (malabsorption of fat soluble)
- ursodexycholic acid
- ampicillin prophylaxis for cholangitis
Jaundiced infant, with elevated direct bilirubin.
what’s your differential? (3)
- cholelithiasis/choledocholithiasis
- bile plug syndrome
- choledochal cyst
other unlikely: infection, tumors
Choledochal cysts
-what congenital anatomic variant is much more common in people with a choledochal cyst, and why?
-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.
Choledochal cysts
-most feared complication
-Biliary adenocarcinoma (2.5-15% incidence)
Choledochal cysts
- most common symptoms for pts >1 year old: (3)
- late complications
- pain
- intermittent jaundice
- mass
- cirrhosis, portal HTN
- biliary adenocarcinoma
Choledochal cysts
- best test to dx
- most common tx
- Ultrasound
- Remove bile duct/cyst, attach intestine directly to liver
(hepaticojejunostomy, hepaticoduodenostomy)
You see an infant vomiting yellow/green material.
Think what?
Bilious emesis is a surgical emergency!
Malrotation of gut:
-what is the normal embryologic process, and what happens with malrotation?
- normal: GI tract rotates 270 degrees counterclockwise
- malrotation: Gut twists on itself, causing volvulus–lack of mesenteric blood flow means twisted gut segment can die
What are Ladd bands, and what’s their danger?
Ladd bands: fibrous peritoneal tissue that connects cecum to abdominal wall.
In malrotation, Ladd bands cross the duodenum and can cause duodenal obstruction
Malrotation of gut:
- How to dx?
- describe surgical tx
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
Duodenal atresia
clinical presentation (3)
- polyhydramnios in utero (no swallowing of amniotic fluid)
- ‘double bubble’ sign
- bilious vomiting
Duodenal atresia
-assoc with what other congenital problem(s)?
- Down’s syndrome
- also other cardiac, genitourinary, anorectal abnormalities
Jejunoileal Atresia
- pathogenesis
- what are 2 possible causes?
- 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
Duodenal atresia:
- pathogenesis
- during what weeks?
- In utero, duodenaum passes through a solid phase, then lumen opens during weeks 8-10
- insult during that time can result in duodenal atresia
Meckel’s diverticulum
-is this a ‘true’ diverticulum? why?
- Yes, b/c it contains all 4 layers of the bowel wall:
1. mucosa
2. submucosa
3. muscularis propria
4. serosa
Meckel’s diverticulum
-pathogenesis
-failure of the vitelline duct to involute. Vitelline duct connects GI lumen with yolk sac in utero
Meckel’s diverticulum
-rule of 2’s (5)
- occurs in 2% of population
- 2 types of abnormal lining (stomach and pancreas)
- located within 2 feet of ileocecal valve
- 2 inches in length
- symptoms by age 2
Meckel’s diverticulum
-symptoms: (3)
- bleeding
- blockage of intestine
- inflammation
most cases are asymptomatic
Hirschsprung’s disease
- pathogenesis
- associated with what congential problem(s)?
- 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
Hirschsprung’s disease
-specific genetic mutation
RET mutations are most common.
RET is a receptor tyrosine kinase that transduces growth/differentation signals.
Hirschsprung’s disease
-what invasive test to dx?
Suction Rectal biopsy
-special biopsy that takes all layers of gut wall to search for ganglion cells
Hirschsprung’s disease
-clinical presentation (3)
typically newborn:
- failure to pass meconium
- bilious emesis
- enterocolitis (life threatening)
Necrotizing enterocolitis
- classic presentation
- classic population
-classically a premature infant presents a few weeks after birth with abdominal distention and increased difficulty breathing
Necrotizing enterocolitis
-what are 3 significant factors in its pathogenesis?
- prematurity
- dysbiosis (alteration of normal gut flora)
- formula feeding (you should feed infant human milk)
Necrotizing enterocolitis
-clinical presentation (6)
- abdominal distention
- feeding intolerance/emesis
- rectal bleeding
- abdominal wall erythema
- temp instability/apnea/bradycardia
- pneumatosis on xray (gas cysts in bowel wall)
Necrotizing enterocolitis
-list stages of disease and their characteristic symptoms
Stage 1: feeding intolerance
Stage 2: pneumatosis intestinalis (gas cysts in colon wall)
Stage 3: ascites, perforation, peritonitis
Necrotizing enterocolitis
- mortality rate
- after tx, there is increased risk of what? (3)
- mortality 20-30%
- Increased risk of:
1. short gut syndrome (after removing bowel)
2. neurodevelopmental delay
3. bronchopulmonary dysplasia
Anorectal malformation
-associated with what congenital disorders? (2)
- Down’s
- VACTERL complex
vertebral, anorectal, cardiac, TEF, renal, limb
VACTERL association
vertebral
anorectal
cardiac
TEF
esophageal atresia
renal
limb
Anorectal malformation
- pathogenesis
- how do males and females typically present differently?
- 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
Anorectal malformation
-symptoms after surgical treatment
100% will have periodic constipation. Anorectal region is missing the nerves that make rectum relax in response to rectal distention.
