Module 8: Fetal GI Flashcards
What anomalies does cloacal exstrophy include? (4)
- Bladder exstrophy
- Omphalocele
- Imperforate anus
- Spina bifida
What fetal assessments are done in the presence of gastroschisis?
BPP and non-stress test (NST always done regardless of BPP results).
What is body stalk associated with?
- Limb defects (missing limbs or club feet)
- Short or absent cord
What is gastroschisis?
A defect in the abdominal wall to the right of the umbilical insertion that allows bowel to float freely in the amniotic fluid due to no covering membrane.
What type of omphalocele has a higher association of having a chromosomal abnormality?
A small omphalocele containing only bowel
How do you assess echogenic bowel on US?
Turn down gains to see if the bone or bowel disappears first.
If bowel is still visible after bone disappears then it’s echogenic bowel.
What is Esophageal Atresia associated with?
- VACTERL
- Trisomy’s
- Heart defects
How should bowel appear on US inutero?
As echogenic as bone.
What complications can arise from gastrochisis?
- Small hole can affect blood supply to herniated bowel
- Severe pulling may cause ascites or perforation (leading to meconium peritonitis).
What is umbilical vein varix?
A dilation of the umbilical vein after it enters the fetal abdomen.
What is meconium?
Fetal stool
What lab value will be increased in the presence of an omphalocele or gastoschisis?
MS-AFP
Is the fetal colon active inutero?
No
What is esophageal atresia?
Absence of a segment of the esophagus
What is an omphalocele?
A defect at the base of the cord allowing abd contents to herniate into the umbilical cord.
What is echogenic bowel associated with? (4)
- Cystic fibrosis
- Chromosomal abnormalities
- TORCH infections from the mother
- Meconium peritonitis
What is the etiology of Esophageal Atresia?
Unknown
What is a persistent right umbilical vein?
During early embryogenesis there are two umbilical veins but only one remains(the left), abnormally the right umbilical vein may persist also.
What increases the risk of thrombus in the umbilical vein?
Umbilical vein varix
What is meconium peritonitis?
When a bowel obstruction perforates the bowel wall meconium can leak out and cause peritonitis (infection/inflammation of the peritoneum).
What should the small bowel diameter of a term fetus be?
Less than 12 mm
What should the colon diameter of a term fetus be?
Less than 18 mm
What is the US appearance of hepatic calcification?
Echogenic or hyperechoic focus in the liver that may shadow.
What is duodenal atresia?
Common small bowel obstruction
What is malrotation of bowel?
A shortened mesenteric attachments obstructs the duodenal bends causing abnormal rotation and placement of the intestines.
What may an Omphalocele contain?
Bowel, stomach and liver
What Trisomy’s are most commonly associated with omphalocele and what other abnormalities does it appear with?
Most common = T18 and T13
Also:
- T21
- Turners
- Triploidy
What bowel has peristalsis?
Dilated small bowel
(dilated large bowel does not).
Why may echogenic debris be seen in the stomach?
After amniocentesis, blood in the amniotic cavity may be swallowed by the fetus.
What syndromes is gastoschisis associated with?
None
What can a large omphalocele be associated with?
- Beckwith Wiedemann (over-growth syndrome)
- Pentalogy of Cantrell
- Trisomy 18
What is the US appearance of duodenal atresia?
Two stomachs = Stomach and 1st portion of duodenum
“Double bubble”
How does the persistent right umbilical vein travel?
Along the right side of the GB and turns toward the stomach instead of away.
What may mimic gastrochisis?
A ruptured Omphalocele
How often is duodenal atresia associated with other anomalies and what are they? (4)
50%
- Trisomy 21
- Cardiovascular
- Polyhydramnios
- Other bowel abnormalities
What so higher atresia (high blockages) usually present with?
Polyhydramnios
What is the cloaca?
The rectum and urogenital sinus develop from a primitive structure called the cloaca
What is Esophageal Atresia associated with?
Tracheoesophageal
fistula
What is bladder extrophy caused by?
A sporadic defect in the development of cloacal membrane.
What is important to document in the presence of an Omphalocele?
- Membrane surrounding contents
- Cord at centre of mass
- What organs have herniated
- Presence of ascites
What is meconium ileus?
An obstruction of the small bowel with meconium almost exclusively due to cystic fibrosis.
What may bladder exstrophy be mistaken for?
Omphalocele
What is the function of the fetal colon?
To collect meconium
How does Meconium peritonitis appear on US?
Appears as echogenic reflectors throughout the bowel.
What is VERY important to be aware of when scanning bowel?
A transducer frequency of greater than or equal to 5 mhz will make bowel appear hyperechoic in a normal fetus.
What is body stalk anomaly?
A fatal abdominal wall defect associated with multiple congenital abnormalities (herniations, ectopic cordis, etc).
What increases the risk of gastrochisis?
- Substance abuse
- Some medications
- Younger women
- Smokers
What is the US feature of meconium ileus?
Echogenic bowel
What are the US features of bladder exstrophy? (3)
- Absent bladder with a soft tissue anterior mass
- Low cord insertion
- Malformed genitalia
Review images
….
What is the current treatment of gastrochisis?
Water bag silo pushes bowel back into abdomen within 72 hrs (no surgery needed).
What are the percentages of VACTERL anomalies?
- Vertebral anomalies 60%
- Anal atresia 60%
- Cardiac anomalies 60%
- Tracheoesophageal fistula 85%
- Renal abnormalities 60%
- Radial limb anomalies 65%
What should be assessed when scanning a fetal abdomen? (7)
- Intact abdominal wall
- Normal situs
- Normal cord insertion
- Skin thickness
- Fluid collections
- Appropriate size for dates
- Bowel echogenicity
What are the abdominal contents covered by in an omphalocele?
Membrane: peritoneum and amnion
What are the common origins of abdominal cysts?
- Mesenteric or omental
- Ovarian
- Choledochal cyst on fetal CBD
- Hepatic
What is another name for body stock anomaly?
Limb-body-wall complex
Why are fetal assessments performed regularly in the presence of gastrochisis?
High still birth rate = 12%
What is hepatic calcification due to? (3)
- TORCH (maternal CMV passed onto fetus)
- Emboli
- Ichemic damage of liver tissue and necrosis
What happens to the fetal gut normally?
At 8 weeks it herniates, rotates 90 degrees and returns back to the abdomen by 12 weeks.
What is volvulus?
When bowel twists around its own blood supply (SMA)
What are the US features of Esophageal Atresia?
- Small/absent stomach (depends if fistula is present connecting the esophagus through the trachea)
- Polyhydramnios
- Dilated prox esophagus
- Fetal vomiting
