OBGYN: Module 8: Abnormalities of the fetal GI tract Flashcards
When we do a ultrasound survey of the Fetal GI tract what do we look for?7
- Intact abdominal wall
- Normal situs
- Normal cord insertion
- Skin thickness
- Fluid collections
- Appropriate size for dates
- Bowel echogenicity
What does this image represent?
2 UA
What are some wall abnormalities?4
- Omphalocele
- Gastroschisis
- Body stalk anomaly
- Bladder and cloacal exstrophy
What is normal gut herniation during 1st semester?
At 8 weeks- gut herniates outside the fetal abdominal cavity and rotates 90 degrees and returns back to abdomen by 12 weeks
What is a omphalocele?
Defect at the base of the cord where the abdominal contents herniate into the umbilical cord
What does this image represent?
Omphalocele
What is the abdominal contents covered by with omphaloceles?
Membrane most likely peritoneum and amnions
What might omphaloceles contain?3
- Bowel
- Stomach
- Liver
Omphaloceles lead to an increase in what hormone?
MSAFP
A small omphalocele containing bowel only has a higher association of having what?
A chromosomal abnormality
A large omphalocele can be associated with what anomalies? 3
- Beckwith - weidmann (1in 7)
- Pentalogy of cantrell
- Trisomies
In terms of omphaloceles and abnormalities, prognosis depends on what?
Associated anomalies
Which two trisomy’s are associated with omphaloceles?
T13 and T18
Besides T18 and T13, omphaloceles are reported to appear with what? 3
- T21
- 45XO
- Triploidy
What does this image represent?
Small omphalocele containing bowel only carry a higher risk of having chromosomal abnormalities
What does the sonographer need to establish in terms of omphalocele sonographically? 5
- Is there a membrane surrounding contents
- Is there a cord at the center of the fetal abdomen
- Contents seen within the omphalocele
- Presence of ascites
- Other associated anomalies
What does these images represent?
Omphaloceles
What is gatroschisis?
A defect in abdominal wall to the right of the umbilical cord insertion
What does the bowel look like with gastroschisis?
Bowel is freely floating in the amniotic fluid
Is there a covering membrane with Gastroschesis?
No
Is gastroschisis associated with other syndromes?
Typically no
What happens to MSAFP with gastroschisis?
Increases
What are some risk factors associated with gastroschisis?4 (what might lead to the disease)
- Substance abuse
- Some medications
- Younger women
- Smokers
What is the occurrence rate of still birth rate with gastroschisis? What do we do to prevent this?3
- Up to 12%
- Fetal assessments performed regularly
- BPP and NST - regardless of the BPP score a NST Is performed (Non stress test)
What does this image represent?
Gastroschisis
What does this image represent?
Gastroschisis
What does this image represent?
Gastroschisis
What does this image represent?
Gastroschisis
What does this image represent?
Bowel
In terms of differentiating omphaleceles and gastroschisis how do we determine the difference between the two
Determine contents of the herniated structure
In terms of differentiating omphaleceles and gastroschisis, what may affect blood supply to both
A small hole or defect may affect blood supply to herniated structures
In terms of differentiating omphaleceles and gastroschisis, severe pulling of both might cause what? what might this lead to?
- Severe pulling may cause ascites or perforation
- Which can lead to meconium peritonitis
A ruptured omphalocele can mimic what?
A ruptured omphalocele can mimic a gastroschisis
In terms of omphaleceles and gastroschisis. what should we do for follow ups?
Measure bowel diameter for further follow up
What does this image represetn?
Bowel vs cord
What does this image represent?
Gastroschisis
What does this represent?
Gastroschisis
What does the silo do for gastroschisis post partum?
Water in bag pushes the bowel back into the abdomen
What is a body stalk anomaly?
Severe abdominal wall defect which happens with there is a failure of abdominal wall to close
How common is body stalk anomalies?
Rare
What happens with body stalk anomalies?
Abdominal organs lie outside the abdominal cavity, covered by amnion and directly attached to the placenta
What are some major body stalk anomalies?3
- Spine anomalies
- Thoracoabdominoschisis or abdominaoschisis
- Limb defects
What is body stalk anomalies sometimes referred to as?
Limb- body wall complex
What are some sonographic features of body stock anomalies? 8 (4)
- Abdominal wall defect
- Absent umbilical cord
- Severe scoliosis
- NTD
- Ectopic cordis or other cardiac defects
- Facial clefts may be present
- Missing limbs or club feet
- Low fluid
What does this image represent?
Limb body wall
What does this image represent?
Limb body wall
What is extrophy?
The congenital turning inside out of an organ
What is extrophy caused by?
Defect in developmental of cloacal membrane
What happens with bladder exstrophy?
failure of closure of the bladder, lower urinary tract, overlying symphysis pubis, rectus, muscle and skin
Is bladder exstrophy sporadic?
Yes
What happens with MSAFP with Bladder exstrophy?
Increases
What are some sonographic signs of bladder exstrophy?4
- Absent Bladder with a soft tissue anterior mass
- Low umbilical cord insertion
- Malformed genitalia
- May be mistaken for an omphalocele
What does this image represent?
Bladder exstrophy
Bladder exstrophy may occur with or without what? What does this mean?
Cloacal extrophy and has a better prognosis
What does this image represent?
Cloacal extrophy
Clocal exstrophy includes what syndromes?4
- Bladder extrophy
- Omphalocele
- Imperforate anus
- Spina bifida
With cloacal exstrophy the rectum and the urogenital sinus develop from what?
From a primitive structure called the cloaca
What does this image represent?
Cloacal exstrophy in transverse
What does this image represent?
Cloacal exstrophy SAG and meningocele
What are some abnormalities of the fetal GI Tract?3
- Atresia or stenosis of the Esophageal and duodenal
- Meconium ileus
- Meconium peritonitis
What is esophageal atresia?
Absence of a segment of the esophagus
What are two types of esophageal atresia?
- Isolated esophageal atresia
- Atersia with TE fistula
What is esophageal atresia usually associated with?
Tracheoesophageal fistula
What is the etiology of esophageal atresia?
Unknown
In fetal development esophagus and trachea develop from what?
A common primitive pharyngeal cavity
What is three sonographic appearances associated with of esophageal atresia? What does this cause the fetus to do? What three anomalies is it assocaited with?
- Small or absent stomach
- Polyhydraminos
- Dilated proximal esophagus in neck
- Fetal vomiting
- Associated with other anomalies such as VACTERL, T21, heart defects
Esophageal atresia and small or absent stomach depends on what?
Whether a fistula is present connecting the esophagus through the trachea
What does this image represent?
Esophageal atresia and TE fistula
What does this image represent?
Persistent small stomach and cystic area in neck
What does this image represent?
Absent fetal stomach
What does VACTERAL stand for?
What is the most common congenital small bowel obstruction?
Duodenal atresia
What is the sonographic appearance of duodenal atresia?
2 stomachs
What is a duodenal atresia sign?
double bubble
Duodenal atresia is 50% associated with what other anomalies?3
- Cardiovascular
- T21
- Other bowel abnormalities
50% of duodenal atresia cases have what?2 (s/s)
- Polyhydraminos
- Symmetrical IUGR
What does this image represent?
Duodenal atresia
A high GI atresia typically presents with what? (s/s)
Polyhydraminos
Lower obstructions do not present with what? What two things happen as a result?
Polyhydraminos like
1. Fetal colon is not active in uteri
2. The colon is only collecting meconium
Dilated small bowel has what?
Peristalsis
Dilated large bowel does not have what?
Peristalsis
What is the colon diameter in a term fetus?
<18mm
What is the diameter of a small bowel?
<12mm
Any bowel above what size is abnormal?
18mm
What does this image represent?
Small bowel obstruction
What does this image represent?
Small bowel obstruction
What does each three of these bowels represent?
a. Normal
b. Malrotation
c. Malrotation with volvulus
What is volvulus?
Bowel twisting on its own blood supply
What is meconium ileus? What does the fetus do with this?
- Obstruction of small bowel with meconium
- Typically liquid material the fetus ingests
Meconium ileus is almost exclusively due to what?
Cystic fibrosis which is a dysfunction of exocrine and mucus producing gland
How does the meconium appear with cystic fibrosis? How is bowel mobility with this?What does this result in? 3
- Thickened and sticky
- Bowel motility is poor
- Resulting in obstruction
What is the sonographic appearance of meconium ileus?
Echogenic bowel
On ultrasound echogenic bowel should be as echogenic as what?
Bone
If we suspect echogenic bowel what should we do?
Turn down gains to see which disappears first, bone or bowel
What do we need to watch out for with echogenic bowel DDX? What do we need to do?
- Watch transducer frequency, >5MHz bowel will appear hyperechoic in a normal fetus
- Use split screen for comparison
Echogenic bowel is associated with what? 4
- Cystic fibrosis
- Chromosomal abnormalities
- TORCH infections from the mother
- Risk of meconium peritonitis
What does this image represent?
Meconium Ileus
What does this image represent?
Echogenic bowel
Any bowel obstruction can lead to what?
Dilated bowel proximal and perforation of the bowel
Perforation of the bowel leads to what?
The contents of the fetal bowel, meconium, leaking into the peritoneum
Meconium is sterile, what does this mean?
No bacterial contamination occurs
Leaking meconium causes what?
An inflammation of the peritoneum, which reacts by forming calcium deposits
What is the sonographic appearence of meconium peritonitis?3
- Appears as echogenic reflectors throughout the bowel2
- Polyhdraminious
- Ascites and hydrops as obx progresses
What is umbilical vein varix?
Dilation of the umbilical vein after it enters the fetal ambdomen
Umbilical vein varix results in what kind of risk?
Increase risk of thrombus in umbilical vein as blood slows down through dilation
What does this image represent?
Varix
When do we see perisistent right umbilical vein?
During early embryogenesis there are 2 umbilical veins
With persistent right umbilical veins, normally the right and left do what?
The right regresses and the left remains
What does a persistent right umbilical vein look like?
Typical hocky stick appearance of UV
If persistent right umbilical vein doesn’t travel normally, what happens?
The right umbilical vein travels along the right side of the gall bladder and turns towards the stomach instead of away
What does this image represent?
Normal vs Persistent right umbilical vein
Persistent right umbilical vein results in what?
Increased risk of heart defects
With persistent right umbilical vein, what is indicated?
Fetal echo is indicated
Hepatic calcifications may be due to what?4
- TORCH
- Emboli
- Ischemic damage of liver tissue and necrosis
- If on periphery, meconium peritonitis
What is the sonographic appearance of hepatic calcification?2
- Echogenic or hyperechoic focus
- May shadow
What does this image represent?
Hepatic calcification
Hepatic calcification is due to what?
Maternal CMV infection passed on to the fetus
What is the origin of abdominal cysts?4
- Mesenteric or omental
- Ovarian if fetus is female
- Choledochal cyst on the fetal CBD
- Hepatic
What is the sonographic appearance of abdominal cysts?
Anechoic structure with through transmission and thin walls
With abdominal cysts what must we try to figure out?
The origin
What kind of abdominal abnormalities are seen in the stomach?
Echogenic debris within the stomach
In terms of echogenic debris seen in the stomach, when will se see it? 2
- After an amniocentesis
- When intrauterine bleeding has occurred
Why do we see echogenic debris in stomach post amniocentesis?
Caused by blood leaking into the amniotic cavity after an amniocentesis. The fetus swallows the blood resulting in echogenic debris in stomach
What does each of these images represent?
- Debris in stomach
- Fetal gallstones