Topic 6 - Fetal chest and abdomen

Question 1

There are four factors, other than normal embryologic development, that are very important for normal lung development which are

Answer 1

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.

Question 2

Most cases of GI atresia are thought to represent…

Answer 2

a failure of recanalization of the bowel lumen, which is a solid tube early in fetal life.

Question 3

What is the normal appearance of the gallbladder?

Answer 3

Oblong echolucent structure in the anterior liver
Generally 45 degrees to the right of midline
inferior to umbilical vein

Question 4

What do abdominal wall muscles look like and why is this important?

Answer 4

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)

Question 5

What is the incidence of different types of CDH?

Answer 5

left sided in 75-90 percent

bilateral in < 5 percent of cases

Question 6

Where does CDH predominantly occur?

Answer 6

Occur predominantly through the posterolateral foramen of Bochdalek

Question 7

What does the mass effect of CDH impact upon?

Answer 7

the normal development of the foetal cardiac and pulmonary systems

Question 8

What is the sonographic appearance of CDH?

Answer 8

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,

Question 9

WHat is an indicator of left CDH?

Answer 9

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

Question 10

WHat is an indicator of right CDH?

Answer 10

Liver herniates into the chest
Mediastinal shift to the left
Absence of the right side of the diaphragm is a key sign

Question 11

Why can right CDH be difficult to identify?

Answer 11

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

Question 12

What are some poor prognostic factors for CDH?

Answer 12

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

Question 13

What is the most obvious sign of CDH? Which other signs will you look for when you suspect a CDH?

Answer 13

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.

Question 14

What does CPAM stand for?

Answer 14

Congenital pulmonary airway malformation

Question 15

What causes CPAM?

Answer 15

results from a pulmonary insult during embryologic development before the seventh week of gestation

Question 16

What is the classification system for CPAM called?

Answer 16

Stocker

Question 17

What are the three types of CPAM?

Answer 17

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).

Question 18

What is a helpful sign in differentiating CPAM from sequestration?

Answer 18

Systemic blood supply from the descending aorta to the lesion helps to identify it as a BPS

Question 19

What is the sonographic appearance of BPH?

Answer 19

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)

Question 20

What is gastroschisis?

Answer 20

full-thickness defect in the anterior abdominal wall immediately to the right of the umbilical cord insertion
The umbilical cord itself is normal

Question 21

What are some risk factors for gastroschisis?

Answer 21

More common with teenage mothers
factors associated with gastroschisis include use of tobacco, illicit drugs, and pseudoephedrine and possible agricultural chemicals

Question 22

What is the sonographic criteria for gastroschisis?

Answer 22

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

Question 23

What are some associated condition for gastroschisis?

Answer 23

An increased risk of preterm birth, fetal growth restriction (up to 60% of cases) and stillbirth (4.5%-12%)
No association with aneuploidy

Question 24

What is an omphalocele?

Answer 24

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.

Question 25

What is the sonographic criteria for omphalocele?

Answer 25

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.

Question 26

What does omphalocele increase the risk of?

Answer 26

increased risk for polyhydramnios, ascites, fetal growth restriction, and stillbirth

Question 27

What do you do if omphalocele is detected?

Answer 27

search carefully for other fetal anomalies; arrange for detailed fetal echocardiogram; and recommend amniocentesis.

Question 28

What is omphalocele associated with?

Answer 28

chromosomal abnormalities (10%-30%) and additional structural abnormalities (55%-58%) most common aneuploidies are trisomies 13 and 18. risk of genetic abnormalities is higher

Question 29

What different types of omphalocele exist and how do they affect likely associations?

Answer 29

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

Question 30

What is the pentalogy on cantrell?

Answer 30

``` Sternal cleft Ventral diaphragmatic hernia Omphalocele Intracardiac anomalies Ectopia cordis ```

Question 31

What can esophageal atresia cause?

Answer 31

Difficult to diagnose absent or small stomach polyhydramnios the esophageal pouch sign (fluid collection in the blind end of the esophagus)

Question 32

What are the differentials for a dilated stomach?

Answer 32

normal variation in stomach size and GI atresia (e.g., duodenal atresia, pyloric atresia) as well as pyloric stenosis

Question 33

What does the diagnosis of dilated stomach required?

Answer 33

the diagnosis requires that the stomach be persistently dilated throughout a 30-minute assessment as well as on successive examinations

Question 34

What can a right sided stomach indicate?

Answer 34

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

Question 35

What can midline stomach represent?

Answer 35

intestinal malrotation

Question 36

What is the significance of an intraluminal gastric mass?

Answer 36

This finding is nonspecific when found in isolation it is most likely to be a normal finding. Such debris most often represents blood, skin cells, or meconium swallowed by the fetus

Question 37

Where may the bowel be obstucted?

Answer 37

duodenal, jejunal, illeal or meconium illeus

Question 38

What is the most common cause of bowel obstruction?

Answer 38

Duodenal stenosis or atresia

Question 39

What are the associations of duodenal atresia?

Answer 39

Associated anomalies are common (50%) 30% to 44% of cases of duodenal atresia are associated with trisomy 21 Duodenal atresia is also associated with anomalies of the VACTERL spectrum presence of severe polyhydramnios (which may not be present until the late second or third trimester)

Question 40

What is the important sonographic sign in duodenal atresia?

Answer 40

Double bubble

Question 41

What is common underlying cause of jejunal obstruction?

Answer 41

Cystic fibrosis

Question 42

What is the sonographic appearance of jejunal/illeal obstruction?

Answer 42

dilated loops of bowel most frequently without a dilated stomach echogenic bowel, reflecting thickened meconium due to the intestinal stasis. Ascites and abdominal calcifications can be seen in cases of obstruction complicated by perforation

Question 43

What is the cut off value of a dilated bowel loop?

Answer 43

The cutoff used to define dilated small bowel is greater than 7 mm for loop diameter or greater than 13 mm for loop length.

Question 44

How are polyhydramnios and bowel obstruction level related?

Answer 44

rate of polyhydramnios decreases as the site of bowel obstruction becomes more distal

Question 45

When is echogenic bowel appearance normal?

Answer 45

Because the echogenicity of normal bowel increases throughout pregnancy, the finding of echogenic bowel becomes normal in the third trimester.

Question 46

What is echogenic bowel associated with?

Answer 46

Aneuploidy (usually 21, less commonly 13, 18 and 45,xo (turner)) Cystic fibrosis Intramniotic bleeding (placental hemorrhage, post procedure) Fetal infection (CMV, parvovirus, herpes) GI tract atresias FGR Fetal anemia Fetal demise

Question 47

How should pregnancies with echogenic bowel be evaluated?

Answer 47

genetic counseling and consideration of amniocentesis or cell-free fetal DNA testing parental screening for cystic fibrosis maternal serology for viral infections, including CMV and parvovirus B19 detailed sonographic assessment for associated structural anomalies or soft markers, signs of bowel obstruction, assessment of fetal biometry, placental morphology, and amniotic fluid follow-up for growth Information regarding episodes of vaginal bleeding or invasive testing earlier in pregnancy should be recorded.

Question 48

What are some associations with hepatomegaly?

Answer 48

fetal hemolytic anemia metabolic and storage diseases fetal infections liver masses hepatic congestion secondary to cardiac failure overgrowth syndromes such as Beckwith-Wiedemann syndrome trisomy 21

Question 49

Conditions associated with hepatic calcifications?

Answer 49

Normal variant—majority of cases when isolated or few Aneuploidy Fetal infection—CMV, parvovirus B19, varicella, herpes simplex, toxoplasmosis Hepatic vascular insult/ischemia Hepatic mass

Question 50

What should hepatic calcifications be distinguished from?

Answer 50

should be distinguished from peritoneal calcifications that outline the liver surface and peritoneal cavity, which can be secondary to meconium peritonitis and may therefore be associated with cystic fibrosis.

Question 51

What is it important to do if you see hepatic calcifications?

Answer 51

assess the size, number and distribution of calcifications Determine if associated masses are present Document normal flow in the liver Search for other signs of fetal infection Assess for structural and growth anomalie’s Genetic counseling and infection screening should be offered in these cases

Question 52

Name the various hepatic masses

Answer 52

Majority are hypoechoic or cystic Hepatic cysts Hemangiomas Abnormal myelopoiesis in fetuses with trisomy 21 Solid echogenic masses may also be identified such as Hamartoma (cystic or mixed cystic solid) Adenoma Hepatoblastoma Use colour flow to determine vascularity Vascular lesions include; Congenital hemangiomas (mostly small and unlikely to show up) Hepatoblastomas Large vascular lesions may lead to high output cardiac failure and hydrops, fetal anemia, thrombocytopenia

Question 53

What can non visualisation of the gallbladder mean?

Answer 53

Associated with agenesis/atresia, cystic fibrosis, aneuploidy and biliary atresia

Question 54

What is splenomegaly associated with?

Answer 54

Associated with conditions similar to those associated with hepatomegaly hemoltic fetal anemia fetal infections metabolic storage disorders trisomy 21 overgrowth syndromes (Beckwidth-Wiedemann)

Question 55

What are some sonographic indicators of GI tract anomaly?

Answer 55

``` non-visualisation of the stomach dilated bowel (stomach, duodenum, small bowel or colon) ascites hyperechogenic bowel peritoneal calcification liver calcifications intra-abdominal cyst enlarged liver (uncommon gastrointestinal pathology, most frequently hydrops, heart failure or viral infection). ```

Question 56

What are the possible causes of non visualisation of the stomach?

Answer 56

Esophageal obstruction Disorders effecting swallowing Severe olio or anhydramnios Displacement of the stomach

Question 57

What should you do when you cant see the stomach?

Answer 57

allow sufficient time for it to fill, in case it has recently emptied the stomach will fill during a 30-minute examination. Careful attention must be paid to the amniotic fluid volume (oligohydramnios or polyhydramnios) general tone and presence of swallowing movements the appearance of the thorax and diaphragm (masses, diaphragmatic hernia) and abdominal situs.

Question 58

What is your differential diagnosis if you don't visualise the stomach at a routine ultrasound examination?

Answer 58

normal stomach that has just emptied displacement of the stomach into the chest or into the umbilical cord non-production of amniotic fluid (renal agenesis) or failure to reach the amniotic cavity (posterior urethral valves) oesophageal atresia situs inversus if you find the stomach in the right upper quadrant

Question 59

Why does Oligohydramnios in the early second trimester carry a very poor prognosis

Answer 59

because of the associated pulmonary hypoplasia.

Question 60

What are the three classifications of urinary malformations?

Answer 60

hydronephrotic renal abnormalities non-hydronephrotic renal abnormalities renal cystic disease

Question 61

What are some causes of hydronephrosis in fetuses?

Answer 61

PUJ obstruction (hydronephrosis, no dilated ureter) Ureterovesical obstruction (dilatation of the ureter with or without hydronephrosis) Posterior urethral valves (in males) Dilated bladder and dilated urethra proximal to the obstruction Reflux with dilated ureter and/or hydronephrosis High-grade vesicoureteral reflux

Question 62

What are the normal limits of renal pelvis diameter?

Answer 62

Prior to 20 weeks <4mm | After 20 weeks, the cut off is controversial, >7-10mm

Question 63

What are the hallmark sonographic signs of bilateral renal agenesis?

Answer 63

Severe oligohydramnios or anhydramnios Persistently non-visualised foetal bladder Renal non-visualisation

Question 64

Is bilateral renal agenesis related to chromosomal and genetic abnormalities?

Answer 64

small percentage of cases it may be secondary to a chromosomal abnormality or part of a genetic syndrome (such as Fraser syndrome), or a developmental defect (such as VACTERL association)

Question 65

Wat is potters sequence?

Answer 65

the atypical physical appearance of a baby due to oligohydramnios experienced when in the uterus. It includes clubbed feet, pulmonary hypoplasia and cranial anomalies related to the oligohydramnios

Question 66

How do the adrenals appear in renal agenesis?

Answer 66

“Lying down” adrenal sign

Question 67

What is the sonographic appearance of unilateral renal agenesis?

Answer 67

Visualisation of only one kidney Compensatory hypertrophy of contralateral kidney Normal bladder and Normal amount of amniotic fluid so difficult to diagnose

Question 68

What is the main pitfall in diagnosing unilateral renal agenesis?

Answer 68

common pitfall is failure to image the renal fossa in the far field because of acoustic shadowing from the spine

Question 69

What are some associations of unilateral renal agenesis?

Answer 69

genital, cardiac, skeletal, and GI abnormalities, as well as with multiorgan syndromes

Question 70

What are some sonographic signs of renal ectopia?

Answer 70

Empty renal fossa Pseudomass in the pelvis represents ectopic kidney In most cases, the crossed ectopic kidney fuses with the normally located kidney (crossed fused renal ectopia), and an enlarged bilobed kidney is seen

Question 71

What are the different types of renal ectopia?

Answer 71

Pelvic kidney Crossed ectopic kidney Crossed fused ectopic kidney

Question 72

What are the two non genetic cystic kidney diseases?

Answer 72

multicystic dysplastic kidney (MCDK) | obstructive dysplasia

Question 73

What are the genetic cystic kidney diseases?

Answer 73

autosomal recessive and autosomal dominant polycystic kidney disease (ADPKD) growing number of cilia-related disorders (ciliopathies)

Question 74

What are the sonographic signs for multicystic dysplastic kidney?

Answer 74

kidney is replaced by multiple cysts of varying sizes. usually no normal renal parenchyma Assessment of the contralateral kidney is very important. In 19% to 24% of cases, multicystic renal dysplasia is bilateral kidney is usually enlarged but can be small Reniform contour can be disrupted

Question 75

What can MCDK mimic?

Answer 75

Hydronephrosis

Question 76

How can you tell the difference between hydronephrosis and MCDK?

Answer 76

In hydronephrosis the dilated calyces are of uniform size, anatomically aligned, communicate with the dilated renal pelvis, kidney usually maintains the reniform contour, with renal parenchyma present peripherally

Question 77

What are the majority of cases of MCDK associated with?

Answer 77

atretic ureter and pelvoinfundibular atresia

Question 78

if the urinary obstruction starts during the first half of gestation what is the most likely renal pathology?

Answer 78

renal dysplasia and sometimes cyst formation will occur | Ostructive cystic renal dysplasia

Question 79

What might cause unilateral renal dysplasia?

Answer 79

can be caused by UPJ obstruction or ureterovesical junction (UVJ) obstruction

Question 80

What might cause bilateral renal dysplasia?

Answer 80

severe bladder outlet obstruction, usually due to urethral atresia or posterior urethral valves

Question 81

The severity of renal dysplasia is related to

Answer 81

the timing and severity of obstruction to urine flow

Question 82

How does renal dysplasia appear on sonography?

Answer 82

size of the kidneys varies from small to normal to markedly enlarged Cysts are usually present in the subcapsular area of the cortex may also demonstrate cortical thinning and increased echogenicity relative to the surrounding fetal structures, with loss of corticomedullary differentiation

Question 83

In a fetus with obstructive uropathy what indicates irreversible damage?

Answer 83

, identification of cortical cysts is indicative of renal dysplasia (i.e., irreversible renal damage)

Question 84

What can we not accurately assess the absence of renal dysplasia?

Answer 84

increased cortical echogenicity is not a specific finding | not all dysplastic kidneys have sonographically visible cysts or increased cortical echogenicity,

Question 85

What are some clues in differentiating MCDk and renal dysplasia?

Answer 85

may be difficult especially in the absence of hydronephrosis. In obstructive cystic renal dysplasia; recognizable parenchyma surrounds the relatively small cysts most often occurs with urethral obstruction - sonographic evidence of urethral obstruction is helpful renal dysplasia from lower UT obstruction frequently involves both kidneys MCDK; no normal renal parenchyma can be identified between cysts cysts can be of varying size and can be quite large in suggesting the diagnosis bilateral MCDK occurs in only 19% to 24% of cases

Question 86

What is the range or autosomal recessive polycystic kidney disease?

Answer 86

perinatal form, severe renal disease, minimal hepatic fibrosis, and early death from pulmonary hypoplasia juvenile form, minimal renal disease, marked hepatic fibrosis, and longer survival

Question 87

What is the sonographic appearance of ARPKD?

Answer 87

Bilateral reniform enlargement Poor delineation of intra renal structures numerous tiny cysts cause increased renal echogenicity the finding of bilateral, very large (>4 standard deviations), diffusely hyperechoic kidneys with poor corticomedullary differentiation, with or without visible cysts, is most likely due to ARPKD Another typical pattern is very large kidneys with a peripheral hypoechoic rim surrounding the centrally increased echogenicity or hyperechoic pyramids (reversed corticomedullary differentiation) When renal function is abnormal, there is oligohydramnios, and the bladder is small or absent

Question 88

What is a sonographic appearance of ADPKD?

Answer 88

In contrast to ARPKD, in which corticomedullary differentiation is absent, increased corticomedullary differentiation has been reported in ADPKD

Question 89

What are some differentials for non visualisation of the bladder?

Answer 89

Renal agenesis ARPKD - When renal function is abnormal, there is oligohydramnios, and the bladder is small or absent Recently emptied