Ultrasound Screening: Soft Markers & Anomalies Part 1

Question 1

What is a vital time point for the 1st trimester ultrasound?

Answer 1

11 weeks
Many structures can’t be seen before then.

Question 2

What is the normal limit for nuchal translucency (NT)?

Answer 2

Less than or equal to 3 mm

Question 3

What measurement is increased nuchal translucency (NT)?

Answer 3

Greater than 3 mm

Question 4

What are the risks associated with increased nuchal translucency (NT)?

Answer 4

aneuploidy (40%)–> example: Tris21
isolated cardiac defect (10%)
segmental aneuploidy (5%)
genetic cause that isn’t chromosomal (5%) ex: Noonan syndrome

segmental aneuploidy = gain or loss of chromosomal segment

About half = normal variation

Question 5

What is the difference between nuchal translucency (NT) and cystic hygroma?

Answer 5

cystic hygroma has loculated cysts

loculated = bubbles or pockets of fluid

Question 6

What risks are assocaited with cystic hygroma?

Answer 6

1. aneuploidy (50%) esp Turner Syndrome (45, XO) and Trisomy 21
2. cardiac defects, non-chromosomal genetic conditions
3. fetal hydrops
4. fetal death in utero (FDIU)

Cystic hygroma–>hydrops–>FDIU

Question 7

Ultrasound soft fluid markers from least to most risk

Answer 7

(least) NT -> cystic hygroma -> fetal hydrops (most)

Question 8

What are hydrops?

Answer 8

2+ abnormal fluid collections & generalized skin edema
(can be fluid in serous cavities: ascites (abdominal fluid), pleural effusions (fluid between lungs & chest), pericardial effusions (extra fluid around the heart)

Question 9

What are the rates of mortality associated with hydrops?

Answer 9

perinatal mortality = 50-98%
liveborn infants = 48% w/in 1 year

Question 10

What factors affect prognosis of a fetus with the finding of hydrops?

Answer 10

• etiology
• GA at onset
• GA at birth
• pleural effusions at birth or not

Question 11

What are the 2 main findings related to hydrops with the worst prognosis and what can these findings lead to?

Especially prior to 20 weeks

Answer 11

1. pleural effusions
2. polyhydramnios (too much amniotic fluid)

• these can lead to pulmonary hypoplasia (incomplete development of the lungs) and preterm rupture of membranes/preterm at birth

earlier than later = bad
extra fluid = bad

Question 12

hydrops + no aneuploidy + no major structural abnormalities =

Answer 12

better prognosis

Question 13

What screening/testing do we offer for US finding at 11-14 weeks of increased NT and/or cystic hygroma?

Answer 13

• whole chromosome aneuploidy
• segmental aneuploidy
• fetal echo at 20 weeks
• eventually maybe single-gene testing if applicable

NIPT,CVS,Amnio

Question 14

What is the major risk to pregnant person if fetal hydrops is found?

Answer 14

Mirror syndrome

Question 15

What is mirror syndrome?

Answer 15

• generalized maternal edema
• pulmonary involvement mirror fetus

Question 16

How can mirror syndrome present in a patient?

Answer 16

• rapid weight gain
• increasing peripheral edema
• progressive shortness of breath
• preeclampsia with severe symptoms

Question 17

What is the solution for mirror syndrome?

Answer 17

delivery
fetus may not be viable

Question 18

What is the increased risk for the USG finding of absent or hypoplastic nasal bone in the 1st or 2nd trimester?

Answer 18

trisomy 21
important note: hypoplastic/absent nasal bone is a normal variant in some people, especially in those of Afro-carribean or Asian decent
2nd note: It is not a birth defect.

Question 19

What screening/testing should we offer for the finding of absent/hypoplastic nasal bone on US?

Answer 19

• best option in this scenario: NIPT
• first trimester screen (as long as lab doesn’t include absent nasal bone in calculations)
• CVS or amnio for diagnostic testing

Question 20

What is omphalocele?

Answer 20

birth defect of the abdominal wall
intestines, liver, and other organs stick outside of the belly through the belly button

(gut spilling out)

Question 21

What testing is appropriate for US finding of NT/cystic hygroma/hydrops?

Answer 21

• NIPT/cfDNA (PPV depends on condition, but is highest for Downs)
• CVS or amnio
• Maternal serum screening/1st trimester screening is NOT an appropriate option

positive NIPT + US finding = very likely to be true positive

NIPT–>CVS/Amnio

Question 22

What is gastroschisis?

Answer 22

birth defect
a hole in the abdomen other than the belly button that allows the baby’s intestines to extend outside of the baby’s body

Question 23

What time point must pass before a ventral wall defect can be diagnosed on US?

Answer 23

12-13 weeks gestational age b/c before this time it is normal for the gut to herniate in to the umbilical cord and then come back in later in deveopment, so if this is seen before 12-13 weeks it wouldn’t be considered a true ventral wall defect

Question 24

What is a ventral wall defect?

Answer 24

gastroschisis or omphalocele as well as some other more rare defects

Question 25

What should be offered for an omphalocele seen on US at 11 weeks?

Answer 25

Return to clinic in 2 weeks to re-assess by ultrasound.
Could also offer FTS or NIPT

Question 26

What options are there for any other suspected major anomalies?

Answer 26

• FTS (not a great option for when an anomaly of any kind is found, but technically is an option)
• NIPT
• CVS or amnio