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SON5023 Obstetrics > Topic 6 - Fetal chest and abdomen > Flashcards

Topic 6 - Fetal chest and abdomen Flashcards

1
Q

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

A

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.

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2
Q

Most cases of GI atresia are thought to represent…

A

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

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3
Q

What is the normal appearance of the gallbladder?

A

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

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4
Q

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

A

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)

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5
Q

What is the incidence of different types of CDH?

A

left sided in 75-90 percent

bilateral in < 5 percent of cases

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6
Q

Where does CDH predominantly occur?

A

Occur predominantly through the posterolateral foramen of Bochdalek

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7
Q

What does the mass effect of CDH impact upon?

A

the normal development of the foetal cardiac and pulmonary systems

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8
Q

What is the sonographic appearance of CDH?

A

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,

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9
Q

WHat is an indicator of left CDH?

A

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

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10
Q

WHat is an indicator of right CDH?

A

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

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11
Q

Why can right CDH be difficult to identify?

A

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

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12
Q

What are some poor prognostic factors for CDH?

A 
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
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13
Q

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

A 
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.
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14
Q

What does CPAM stand for?

A

Congenital pulmonary airway malformation

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15
Q

What causes CPAM?

A

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

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16
Q

What is the classification system for CPAM called?

A

Stocker

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17
Q

What are the three types of CPAM?

A

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).

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18
Q

What is a helpful sign in differentiating CPAM from sequestration?

A

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

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19
Q

What is the sonographic appearance of BPH?

A

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)

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20
Q

What is gastroschisis?

A

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

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21
Q

What are some risk factors for gastroschisis?

A

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

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22
Q

What is the sonographic criteria for gastroschisis?

A

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

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23
Q

What are some associated condition for gastroschisis?

A

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

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24
Q

What is an omphalocele?

A

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.

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25
Q

What is the sonographic criteria for omphalocele?

A

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.

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26
Q

What does omphalocele increase the risk of?

A

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

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27
Q

What do you do if omphalocele is detected?

A

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

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28
Q

What is omphalocele associated with?

A

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

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29
Q

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

A

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

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30
Q

What is the pentalogy on cantrell?

A 
Sternal cleft
Ventral diaphragmatic hernia
Omphalocele
Intracardiac anomalies
Ectopia cordis
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31
Q

What can esophageal atresia cause?

A

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

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32
Q

What are the differentials for a dilated stomach?

A

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

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33
Q

What does the diagnosis of dilated stomach required?

A

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

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34
Q

What can a right sided stomach indicate?

A

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

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35
Q

What can midline stomach represent?

A

intestinal malrotation

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36
Q

What is the significance of an intraluminal gastric mass?

A

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

37
Q

Where may the bowel be obstucted?

A

duodenal, jejunal, illeal or meconium illeus

38
Q

What is the most common cause of bowel obstruction?

A

Duodenal stenosis or atresia

39
Q

What are the associations of duodenal atresia?

A

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)

40
Q

What is the important sonographic sign in duodenal atresia?

A

Double bubble

41
Q

What is common underlying cause of jejunal obstruction?

A

Cystic fibrosis

42
Q

What is the sonographic appearance of jejunal/illeal obstruction?

A

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

43
Q

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

A

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

44
Q

How are polyhydramnios and bowel obstruction level related?

A

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

45
Q

When is echogenic bowel appearance normal?

A

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

46
Q

What is echogenic bowel associated with?

A

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

47
Q

How should pregnancies with echogenic bowel be evaluated?

A

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.

48
Q

What are some associations with hepatomegaly?

A

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

49
Q

Conditions associated with hepatic calcifications?

A

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

50
Q

What should hepatic calcifications be distinguished from?

A

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.

51
Q

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

A

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

52
Q

Name the various hepatic masses

A

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

53
Q

What can non visualisation of the gallbladder mean?

A

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

54
Q

What is splenomegaly associated with?

A

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

55
Q

What are some sonographic indicators of GI tract anomaly?

A 
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).
56
Q

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

A

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

57
Q

What should you do when you cant see the stomach?

A

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.

58
Q

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

A

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

59
Q

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

A

because of the associated pulmonary hypoplasia.

60
Q

What are the three classifications of urinary malformations?

A

hydronephrotic renal abnormalities
non-hydronephrotic renal abnormalities
renal cystic disease

61
Q

What are some causes of hydronephrosis in fetuses?

A

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

62
Q

What are the normal limits of renal pelvis diameter?

A

Prior to 20 weeks <4mm

After 20 weeks, the cut off is controversial, >7-10mm

63
Q

What are the hallmark sonographic signs of bilateral renal agenesis?

A

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

64
Q

Is bilateral renal agenesis related to chromosomal and genetic abnormalities?

A

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)

65
Q

Wat is potters sequence?

A

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

66
Q

How do the adrenals appear in renal agenesis?

A

“Lying down” adrenal sign

67
Q

What is the sonographic appearance of unilateral renal agenesis?

A

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

68
Q

What is the main pitfall in diagnosing unilateral renal agenesis?

A

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

69
Q

What are some associations of unilateral renal agenesis?

A

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

70
Q

What are some sonographic signs of renal ectopia?

A

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

71
Q

What are the different types of renal ectopia?

A

Pelvic kidney
Crossed ectopic kidney
Crossed fused ectopic kidney

72
Q

What are the two non genetic cystic kidney diseases?

A

multicystic dysplastic kidney (MCDK)

obstructive dysplasia

73
Q

What are the genetic cystic kidney diseases?

A

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

74
Q

What are the sonographic signs for multicystic dysplastic kidney?

A

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

75
Q

What can MCDK mimic?

A

Hydronephrosis

76
Q

How can you tell the difference between hydronephrosis and MCDK?

A

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

77
Q

What are the majority of cases of MCDK associated with?

A

atretic ureter and pelvoinfundibular atresia

78
Q

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

A

renal dysplasia and sometimes cyst formation will occur

Ostructive cystic renal dysplasia

79
Q

What might cause unilateral renal dysplasia?

A

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

80
Q

What might cause bilateral renal dysplasia?

A

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

81
Q

The severity of renal dysplasia is related to

A

the timing and severity of obstruction to urine flow

82
Q

How does renal dysplasia appear on sonography?

A

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

83
Q

In a fetus with obstructive uropathy what indicates irreversible damage?

A

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

84
Q

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

A

increased cortical echogenicity is not a specific finding

not all dysplastic kidneys have sonographically visible cysts or increased cortical echogenicity,

85
Q

What are some clues in differentiating MCDk and renal dysplasia?

A

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

86
Q

What is the range or autosomal recessive polycystic kidney disease?

A

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

87
Q

What is the sonographic appearance of ARPKD?

A

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

88
Q

What is a sonographic appearance of ADPKD?

A

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

89
Q

What are some differentials for non visualisation of the bladder?

A

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

SON5023 Obstetrics (9 decks)

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