Topic 6 - Fetal chest and abdomen Flashcards
There are four factors, other than normal embryologic development, that are very important for normal lung development which are
Adequate thoracic space for growth: The thorax may be too small (skeletal dysplasia) or a thoracic mass, diaphragmatic hernia or pleural effusion (hydrops) may leave insufficient thoracic space for the lungs to develop.
Fluid within the lung: This serves as an “intrapulmonary fluid stent” distending the developing airways.
Adequate amniotic fluid: Prolonged oligohydramnios may lead to pulmonary hypoplasia.
Fetal breathing movements: Useful indicator for foetal well-being and is necessary for normal lung development.
Most cases of GI atresia are thought to represent…
a failure of recanalization of the bowel lumen, which is a solid tube early in fetal life.
What is the normal appearance of the gallbladder?
Oblong echolucent structure in the anterior liver
Generally 45 degrees to the right of midline
inferior to umbilical vein
What do abdominal wall muscles look like and why is this important?
The abdominal wall muscles may appear as a hypoechoic rim of tissue deep to the skin and subcutaneous fat. The muscle layer may be mistaken for ascites (pseudoascites)
What is the incidence of different types of CDH?
left sided in 75-90 percent
bilateral in < 5 percent of cases
Where does CDH predominantly occur?
Occur predominantly through the posterolateral foramen of Bochdalek
What does the mass effect of CDH impact upon?
the normal development of the foetal cardiac and pulmonary systems
What is the sonographic appearance of CDH?
presence of stomach bubble, gallbladder or bowel within the thoracic cavity
deviation of the heart and mediastinum
herniated liver
abnormal position of the umbilical and hepatic veins
pleural effusion
polyhydramnios
The abdominal circumference is often small,
WHat is an indicator of left CDH?
Stomach in the chest
Absence of normal stomach below the diaphragm
Potential herniation of the small and large bowel, liver, spleen and kidney into the thorax
Mediastinal shift causing the heart to deviate to the righ
WHat is an indicator of right CDH?
Liver herniates into the chest
Mediastinal shift to the left
Absence of the right side of the diaphragm is a key sign
Why can right CDH be difficult to identify?
Echogenicity of the liver is similar to that of the lung, so visualisation of the gallbladder and hepatic vessels is helpful in confirming diagnosis
Left mediastinal shift is less obvious
What are some poor prognostic factors for CDH?
Right-sided or bilateral hernia Early gestational age at diagnosis Small lung size (measured by lung-to-head ratio or volumetry) Associated abnormalities (structural or chromosomal) Hydrops Polyhydramnios Degree of mediastinal shift Intrauterine growth restriction Liver in chest
What is the most obvious sign of CDH? Which other signs will you look for when you suspect a CDH?
Mediastinal deviation When you suspect a CDH on the basis of mediastinal shift, you should look for other signs that may confirm a CDH. Suggestive signs include: Bowel in the chest abdominal circumference < 5th percentile polyhydramnios in the third trimester Diagnostic signs include: peristalsis in the chest; and paradoxal motion of the abdominal content on fetal inspiration.
What does CPAM stand for?
Congenital pulmonary airway malformation
What causes CPAM?
results from a pulmonary insult during embryologic development before the seventh week of gestation
What is the classification system for CPAM called?
Stocker
What are the three types of CPAM?
Stockers type I (large cysts measuring 2-10 cm)
Stockers type II (multiple small cysts/macro cystic)
Stockers type III (microcystic, appearing as echogenic lesions).
What is a helpful sign in differentiating CPAM from sequestration?
Systemic blood supply from the descending aorta to the lesion helps to identify it as a BPS
What is the sonographic appearance of BPH?
Typically appears as a well-defined, homogeneous, echogenic, wedge-shaped pulmonary mass in the lower lobe
Classically it does not have cystic components, however they can result due to dilatation of the bronchioles or hybrid lesions (CPAM)
What is gastroschisis?
full-thickness defect in the anterior abdominal wall immediately to the right of the umbilical cord insertion
The umbilical cord itself is normal
What are some risk factors for gastroschisis?
More common with teenage mothers
factors associated with gastroschisis include use of tobacco, illicit drugs, and pseudoephedrine and possible agricultural chemicals
What is the sonographic criteria for gastroschisis?
small (2-4 centimetres), full-thickness abdominal wall defect
hyperechoic mass attached to the abdominal wall, immediately right of the cord insertion
normal cord insertion
free floating loops of bowel (often the surface of the mass is ‘lobulated’) characteristic cauliflower-like appearance
no covering membrane
The stomach is often displaced downward within the abdominal cavity
What are some associated condition for gastroschisis?
An increased risk of preterm birth, fetal growth restriction (up to 60% of cases) and stillbirth (4.5%-12%)
No association with aneuploidy
What is an omphalocele?
defect in the anterior abdominal wall at the cord insertion (the skin, muscles, and fascia are missing at the site of the defect).
The sac is covered by a thin membrane which is composed of peritoneum and amnion
There is herniation of abdominal contents into the sac
the cord inserts into the sac.
What is the sonographic criteria for omphalocele?
central, anterior, smooth walled mass containing herniated bowel structures;
umbilical cord inserting into the mass (colour Doppler is useful to determine insertion site); and
membrane (peritoneum and amnion) covering the defect.
What does omphalocele increase the risk of?
increased risk for polyhydramnios, ascites, fetal growth restriction, and stillbirth
What do you do if omphalocele is detected?
search carefully for other fetal anomalies;
arrange for detailed fetal echocardiogram; and
recommend amniocentesis.
What is omphalocele associated with?
chromosomal abnormalities (10%-30%)
and additional structural abnormalities (55%-58%)
most common aneuploidies are trisomies 13 and 18.
risk of genetic abnormalities is higher
What different types of omphalocele exist and how do they affect likely associations?
risk of genetic abnormalities is higher in cases with a small defect when the herniated content is limited to small bowel
liver found in the omphalocele less likely to be associated with chromosomal abnormalities
What is the pentalogy on cantrell?
Sternal cleft Ventral diaphragmatic hernia Omphalocele Intracardiac anomalies Ectopia cordis
What can esophageal atresia cause?
Difficult to diagnose
absent or small stomach
polyhydramnios
the esophageal pouch sign (fluid collection in the blind end of the esophagus)
What are the differentials for a dilated stomach?
normal variation in stomach size and GI atresia (e.g., duodenal atresia, pyloric atresia) as well as pyloric stenosis
What does the diagnosis of dilated stomach required?
the diagnosis requires that the stomach be persistently dilated throughout a 30-minute assessment as well as on successive examinations
What can a right sided stomach indicate?
should raise the possibility of heterotaxy syndrome
characterized by an abnormal symmetry of the viscera and veins and is associated with complex cardiac anomalies, intestinal malrotation, and splenic (asplenia or polysplenia) and hepatic abnormalities.
Because of the combined cardiovascular and GI abnormalities, infant mortality is high
What can midline stomach represent?
intestinal malrotation