+Chapter 37 - Obstetric Ultrasound 2

Question 1

_________ are the most common solid pelvic masses encountered during pregnancy.

Answer 1

Uterine leiomyomas

Question 2

_______ are the most common cystic pelvic masses found in pregnancy.

Answer 2

Corpus luteal cysts

Question 3

_______ cysts form due to an exaggerated corpus luteum response to high levels of β-hCG.

Answer 3

Theca lutein

Question 4

_______ is the single most common cause of a poor neonatal outcome.

Answer 4

Preterm delivery

Question 5

The normal cervical length is ____ mm throughout gestation.

Answer 5

26 to 50 mm

Question 6

______ is measured in sagittal plane between the internal os marked by a V-shaped notch and the external os marked by a triangular echodensity.

Answer 6

Cervical length

Question 7

Dilation of the cervical canal greater than ___ mm is indicative of cervical incompetence.

Answer 7

Greater than 8 mm

Question 8

Normal placenta is first apparent on US at about __ weeks as a focal thickening at the periphery of the gestational sac

Answer 8

8 weeks

Question 9

Normal range of placental thickness

Answer 9

1 to 4 cm

Question 10

_____ is present when part or all of the placenta covers the internal cervical os

Answer 10

Placenta previa

Question 11

______ is present when placental blood vessels, or the umbilical cord, are adherent to the membranes that cover the cervix.

Answer 11

Vasa previa

Question 12

________ is defined as the premature separation of a normally positioned placenta from the myometrium.

Answer 12

Placental abruption

Question 13

_______ is an abnormal adherence of the placenta to the uterine wall

Answer 13

Placenta accreta

Question 14

Invasion of the uterine wall by the placenta is referred to as ____
and
penetration of the uterine wall is _____.

Answer 14

placenta increta; placenta percreta

Question 15

_______ is a benign vascular placental mass supplied by the fetal circulation. It is the most common tumor of the placenta.

Answer 15

Chorioangioma

Question 16

Normal diameter of umbilical cord

Answer 16

1 to 2 cm

Question 17

_______ is caused by the early (generally before 10 weeks GA) disruption of the amnion, enabling the fetus to enter the chorionic cavity.

Answer 17

Amniotic band syndrome

• fetus becomes entangled in fibrous bands that develop within the chorionic cavity

Question 18

_______ are membranous structures that project into the uterine cavity.

Answer 18

Uterine synechiae (amniotic sheets)

Question 19

amniotic fluid index greater than 20 cm or

a single fluid pocket greater than 8 cm deep is strongly suggestive of ________.

Answer 19

polyhydramnios

Question 20

A major complication of severe oligohydramnios is ______.

Answer 20

fetal lung immaturity

Question 21

_______ results from shunting of blood from one twin to the other through vascular connections in the placenta.

Answer 21

Twin transfusion syndrome

Question 22

A detailed US fetal anatomic survey performed at the optimum time of ______ weeks GA will detect the majority of serious structural birth defects.

Answer 22

18 to 22 weeks GA

Question 23

In Down syndrome, pregnancy-associated plasma protein A (PAPP-A) is ___ and β-hCG is ____.

Answer 23

LOW; HIGH

Question 24

____ refers to the normal echolucent space between the spine and the overlying skin at the back of the fetal neck.

Answer 24

Nuchal translucency

Question 25

In the second trimester (19 to 24 weeks), a nuchal thickness measurement of ___ mm is abnormal.

Answer 25

≥6 mm

Question 26

Second-trimester biochemical screening for fetal abnormalities currently includes four serum markers, the “quad test.” These markers are ______.

Answer 26

1. alpha-fetoprotein (AFP) 2. hCG 3. unconjugated estriol (uE3) 4. inhibin A

Question 27

Pregnancies with a fetus having Down syndrome show ____ levels of AFP and uE3 and _____ levels of hCG and inhibin A.

Answer 27

low; elevated

Question 28

In Trisomy 18, AFP, uE3, and hCG are all ____.

Answer 28

In Trisomy 18, AFP, uE3, and hCG are all LOW.

Question 29

______ is the most common chromosome abnormality, increasing in incidence and currently occurring in 1 of 500 births.

Answer 29

Trisomy 21 (Down syndrome)

Question 30

_______ is the second most common chromosome anomaly, occurring in 1 of 3000 births.

Answer 30

Trisomy 18

Question 31

Effective US screening for CNS anomalies can be performed by examination of three crucial axial planes through the fetal brain. (Identify these three planes).

Answer 31

1. transthalamic plane 2. transventricular plane 3. transcerebellar plane

Question 32

The normal cisterna magna measures ___ mm in width.

Answer 32

2 to 11 mm

Question 33

A small cisterna magna ( __ mm) - suggests a Chiari II malformation, but may also be seen with massive ventriculomegaly. A large cisterna magna ( __ mm) - may be a normal variant (mega-cisterna magna) or indicate Dandy–Walker malformation, arachnoid cyst, or cerebellar hypoplasia.

Answer 33

*small cisterna magna (<2 mm) - suggests a Chiari II malformation, but may also be seen with massive ventriculomegaly. *large cisterna magna (>11 mm) - may be a normal variant (mega-cisterna magna) or indicate Dandy–Walker malformation, arachnoid cyst, or cerebellar hypoplasia.

Question 34

The normal ventricular atrium does not exceed __ mm in width at any time during pregnancy.

Answer 34

does not exceed 10 mm - ventricular atrium is measured from its medial wall to its lateral wall

Question 35

The normal cisterna magna measures ___ mm throughout pregnancy.

Answer 35

2 to 11 mm - cisterna magna is measured from the vermis to the occiput

Question 36

3 US signs of ventriculomegaly

Answer 36

1. diameter of the ventricular atrium greater than 10 mm 2. separation of choroid plexus from the ventricular wall by greater than 3 mm 3. “dangling choroid”

Question 37

The most common causes of ventriculomegaly in the fetus are | ____.

Answer 37

Chiari II malformation and aqueductal stenosis

Question 38

_______ is the most common neural tube defect.

Answer 38

Anencephaly

Question 39

_______ are fluid- and/or brain tissue-filled sacs that protrude through a defect in the bony calvarium.

Answer 39

Cephaloceles

Question 40

______ refers to a spectrum of spinal abnormalities resulting from failure of the complete closure of the neural tube.

Answer 40

Spina bifida

Question 41

Spina Bifida ranges from - simple nonfusion of the vertebral arches with intact skin (___________), - to protruding sacs containing only CSF skin (___________), - to sacs with spinal cord or nerve roots skin (___________), - and to a totally open spinal defect skin (___________).

Answer 41

Spina Bifida ranges from - simple nonfusion of the vertebral arches with intact skin (spina bifida occulta), - to protruding sacs containing only CSF (meningocele), - to sacs with spinal cord or nerve roots (myelomeningocele), - and to a totally open spinal defect (myeloschisis).

Question 42

Spina bifida may occur anywhere in the spine but most often occurs in the _____.

Answer 42

lumbosacral region

Question 43

The “lemon sign” refers to __________, causing a lemon-shaped appearance to the head in the axial plane The “banana sign” is produced by compression of the _______ into a banana shape.

Answer 43

* “lemon sign” refers to bossing of the frontal bones, causing a lemon-shaped appearance to the head in the axial plane * “banana sign” is produced by compression of the cerebellar hemispheres into a banana shape.

Question 44

Hydranencephaly refers to total destruction of the cerebral cortex, believed to be caused by the occlusion of the _____.

Answer 44

internal carotid arteries

Question 45

Dandy–Walker malformation results from the maldevelopment of the ____.

Answer 45

roof of the fourth ventricle

Question 46

______ is a fluid collection in the fetal neck caused by failure of the lymphatic system to develop normal connections with the venous system in the neck.

Answer 46

Cystic hygroma

Question 47

_______ is a congenital hamartomatous lesion of the lung, usually affecting one lobe.

Answer 47

Cystic adenomatoid malformation - Type I lesions appear on US as single or multiple cysts larger than 2 cm size. - Type II lesions consist of multiple smaller cysts of uniform size less than 2 cm. - Type III lesions appear as echogenic solid masses because the cysts are microscopic

Question 48

_______ is a mass of lung tissue supplied by systemic arteries and separated from its normal bronchial and pulmonary vascular connections.

Answer 48

Pulmonary sequestration - Intralobar sequestrations (75%) are contained within the pleural covering of an otherwise normal lobe of the lung. Pulmonary venous drainage is maintained. US detection in the fetus is rare. - Extralobar sequestrations, although less common (25%), are much more frequently evident on fetal US. These are accessory lobes, contained within their own pleura, and supplied by both systemic arteries and veins.

Question 49

The apex of the normal heart is directed at the ___ at a 45° angle on the same side as the fetal stomach.

Answer 49

The apex of the normal heart is directed at the left anterior chest wall at a 45° angle on the same side as the fetal stomach. Deviation from this position suggests a cardiac malformation or a thoracic mass.

Question 50

Swallowing begins at _____ weeks GA.

Answer 50

11 to 12 weeks GA

Question 51

By ____ weeks GA, the fluid-filled stomach is normally seen in the left upper quadrant of the fetal abdomen.

Answer 51

18 weeks GA

Question 52

______ is descriptive of fluid distension of the stomach and proximal duodenum.

Answer 52

Double bubble - Fluid distension of the duodenum is abnormal and indicative of duodenal atresia or stenosis, annular pancreas, or volvulus.

Question 53

Bowel obstruction is suggested by dilation of the small bowel of ______.

Answer 53

greater than 6 mm

Question 54

Small bowel is considered abnormally echogenic when its echogenicity is _____.

Answer 54

equal to or greater than that of adjacent bone

Question 55

The most common causes of hydronephrosis in the fetus are | _____ (3).

Answer 55

1. ureteropelvic junction obstruction 2. ectopic ureterocele 3. posterior urethral valves

Question 56

3 definitive evidence of significant hydronephrosis in fetal kidney US.

Answer 56

1. Dilation of the renal pelvis greater than 10-mm AP diameter or 2. greater than 50% of the AP diameter of the kidney in axial section or 3. unequivocal caliectasis

Question 57

Minimal dilatation of the renal pelvis is most often due to _____.

Answer 57

physiologic vesicoureteral reflux - that is normal during the second and the third trimesters

Question 58

A fluid-filled renal pelvis larger than ___ mm warrants attention because it may be a sonographic marker of aneuploidy (Down syndrome) or an early indicator of congenital urinary obstruction.

Answer 58

larger than 3 mm

Question 59

_______ kidney appears as multiple noncommunicating cysts of varying size.

Answer 59

Multi-cystic dysplastic kidney - Because affected kidneys do not function, bilateral multicystic dysplastic kidney is associated with severe oligohydramnios and is not compatible with life.

Question 60

Massive enlargement of both kidneys associated with oligohydramnios suggests _____.

Answer 60

autosomal recessive polycystic disease

Question 61

_______ results from a defect in the anterior abdominal wall nearly always on the right side of the umbilicus.

Answer 61

Gastroschisis - defect is usually 2 to 4 cm in size - Bowel herniates through the defect and floats freely in the amniotic fluid with no covering membrane

Question 62

______________ is a more serious abdominal wall defect. | - The defect is midline at the umbilicus with herniation of abdominal contents into the base of the umbilical cord

Answer 62

Omphalocele - Both liver and bowel are commonly present in the herniation - A membrane consisting of peritoneum and amnion covers the omphalocele - The umbilical cord inserts through the membrane - Associated anomalies are common

Question 63

A ratio of FL to foot length of less than 1 suggests a _____, whereas a ratio greater than 1 is usually associated with a _____.

Answer 63

A ratio of FL to foot length of less than 1 suggests a *skeletal dysplasia, whereas a ratio greater than 1 is usually associated with a *constitutionally small or growth-retarded fetus.

Question 64

______ is the most common lethal skeletal dysplasia.

Answer 64

Thanatophoric dwarfism

Question 65

_______ dysplasia is an autosomal dominant trait that is lethal in homozygous form and nonlethal in heterozygous form.

Answer 65

Achondroplastic dysplasia - Because at least one parent must have the condition, the US diagnosis is made on the basis of proximal limb shortening

Question 66

Osteogenesis imperfecta is a heterogenous group of disorders with both autosomal dominant and recessive inheritance patterns. The hallmark of the disease is ______.

Answer 66

osteoporosis - this may manifest on US as diminished bone echogenicity

Question 67

Clenched hands with overlapping index fingers

Answer 67

trisomy 18

Question 68

Polydactyly with polycystic kidneys suggests ____. "poly poly Mac"

Answer 68

Meckel–Gruber syndrome

Question 69

Hypoplasia of the middle phalanx of the fifth digit in association with femur and humerus shortening suggests ______.

Answer 69

Down syndrome