Chapter 62 The Fetal Abdomen Flashcards

1
Q

what serves as a conduit between the portal and systemic veins?

A

ductus venosus

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2
Q

in what 3 ways do the proportions of the fetal abdomen differ from the adult abdomen

A
  • fetal abdomen is larger relative to body length
  • fetal liver occupies more space in abdomen
  • fetal pelvic cavity is smaller so bladder, ovaries and uterus lie in abdomen
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3
Q

pharynx, lower respiratory system, esophagus, stomach, part of duodenum, liver and biliary apparatus, and the pancreas are all derivatives of what?

A

the foregut

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4
Q

what are the derivatives of the midgut?

A

small intestines, cecum and cloaca, ascending colon, transverse colon

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5
Q

how does umbilical hernia differ from omphalocele?

A

omentum or loop of bowel is covered by subcutaneous tissue and skin

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6
Q

what is the most common malformation of the midgut?

A

Meckel’s diverticulum

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7
Q

what is Meckel’s diverticulum?

A

remnant of the proximal part of the yolk sac that fails to degenerate

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8
Q

the left part of the transverse colon, descending colon, sigmoid colon, rectum, superior portion of the anal canal, epithelium of the bladder, and most of the urethra are all derivatives of what?

A

the hindgut

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9
Q

most fetuses older than _______ should have fluid in their stomachs

A

14-16 weeks

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10
Q

when can the normal esophagus be visualized?

A

second and third trimesters

appears as two or more parallel echogenic lines

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11
Q

where is the abdominal circumference taken

A

at the level of the portal sinus and the umbilical portion of the left portal vein

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12
Q

umbilical vein coarses

A

cephalically

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13
Q

umbilical vein joins _____ in the liver

A

left portal vein

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14
Q

after birth the umbilical vein becomes

A

ligamentum teres

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15
Q

fetus is capable of swallowing to permit visualization of the stomach by

A

11 weeks

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16
Q

when does meconium begin to accumulate

A

15-16 weeks

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17
Q

small bowel is _____ in echogenicity compared to the liver

A

hyperechoic

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18
Q

when can peristalsis be observed

A

after 27 weeks

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19
Q

meconium within the colon appears _____ in echogenicity compared to the liver

A

hypoechoic

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20
Q

hepatic veins and fissures are formed by

A

the end of the first trimester

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21
Q

which lobe of the fetal liver is larger

A

left

22
Q

when may the gallbladder be seen

A

20 weeks

23
Q

the spleen is imaged in what plane

A

transverse

24
Q

how does asplenia appear

A

abnormally positioned liver, gallbladder, IVC and aorta

25
Q

what is common with polysplenia

A

heart block

26
Q

how does polysplenia appear

A

transposition of the liver and stomach, absence of the gallbladder, and disruption of the IVC

27
Q

what is the mortality rate for partial situs inversus

A

90-95% with asplenia and 80% with polysplenia

28
Q

what is the sonolucent band near the fetal anterior abdominal wall that is identified after 18 weeks

A

normal musculature surrounding the abdominal wall

29
Q

pseudoascites is always confined to _____ and never outlines the _____ like true ascites

A

anterior or anterolateral aspect of the fetal abdomen

falciform ligament

30
Q

what may appear with a choledocal cyst

A

a cystic mass adjacent to the fetal stomach and gallbladder

31
Q

what 2 organs may enlarge with Rh-immune disease

A

spleen and liver

32
Q

what is esophageal atresia

A

blockage of the esophagus resulting from faulty separation of the foregut

33
Q

what are the 2 primary sonographic findings with esophageal atresia

A

polyhydramnios and absence of stomach bubble

34
Q

what is the most common coexisting anomaly of esophageal atresia

A

anorectal atresia

35
Q

sonographic findings of duodenal atresia

A

2 echo free structures (stomach and duodenum) appear in upper abdomen
this is termed double bubble sign

36
Q

about 30% of fetuses with duodenal atresia have what

A

trisomy 21

37
Q

how will blockage of the jejunum and ileal bowel segments appear

A

as multiple cystic structures proximal to the site of atresia

38
Q

what are the 5 causes of fetal small bowel obstruction

A
malrotation
atresias
volvulus
peritoneal bands
cystic fibrosis
39
Q

what is a small bowel disorder marked by the presence of thick meconium in the distal ileum

A

meconium ileus

40
Q

meconium ileus is the earliest manifestation of what

A

cystic fibrosis

41
Q

it is important that the small bowel appear _____ during the second trimester

A

echogenic

42
Q

what does VACTERL stand for

A
Vertebral abnormalities
Anal atresia
Cardiac abnormalities
TracheoEsophagela fistula
Renal and Limb abnormalities
43
Q

what is caudal regression syndrome

A

lack of development of the lower limbs

44
Q

in whom may caudal regression syndrome occur

A

fetus of diabetic mother

45
Q

how does anorectal atresia appear sonographically

A

dilated colon and calcified meconium

46
Q

what is Hirchsprung’s disease or mega colon

A

abnormal innervation of the large intestine

47
Q

what is meconium peritonitis

A

fetus has a sterile chemical peritonitis secondary to an in utero bowel perforation

48
Q

how does meconium peritonitis appear sonographically

A

calcifications are seen on the peritoneal surface or in the scrotum

49
Q

what may cause hyperechoic bowel

A

decreased water content, alterations of meconium or both

50
Q

decreased water content may be secondary to what

A

hypoperistalsis

51
Q

in the fetus ascites collects where

A

between the two leaves of unfused omentum

52
Q

ascites usually outlines

A

the falciform ligament and umbilical vein