Genetics Flashcards Preview

OB Ultrasound > Genetics > Flashcards

Flashcards in Genetics Deck (34):
1

an anatomic or structual abnormality which is present at birth

Congenital malformation

2

Percentage of perinatal deaths that are due to the presence of congenital malformations

20%

3

Any substance capable of causing abnormal structure in an embryo

Teratogen

4

Causes of congenital malformations

Genetic factors
Environmental factors
Multifactorial inheritance
Sensitive concept

5

Certain structures are _________ to certain teratogenic agents at given times and only at given times. _______ event cannot influence the development of a structure if it occurs before or after that structure differentiates or develops

Sensitive,
Noxious

6

The three catagories that teratogens are devided into are

1. Physical agents
2. Drugs and chemical agents
3. Maternal factors

7

Radiation,
heat,
mechanical factors like uterine anomalies and fibroids

Physical agents (Teratogen)

8

DES, Coumadin, alcohol, anti-thyroid drugs, methotrexate, retinoic acid/ vitamin A, valproic acid for seizures, trimethadione, thalidomide, methylmercury, and many others

Drugs and chemical agents (Teratogen)

9

Include diseases such as diabetes and sickle cell anemia and maternal infections. There are many others

Maternal factors (Teratogen)

10

Genetic defects that can be identified and diagnosed microscopically

Chromosomal abnormalities

11

__________________ usually affect a large part of the fetus and Genome are associated with multiple anatomic abnormalities, mental retardation and high mortality rate

Major chromosome abnormalities

12

Genetic diseases can be the result of:

*An abnormal number of chromosomes such as 13, 18, 21
*Abnormal structure of one or more chromosomes
*Single gene defects which are inherited as autosomal dominant or autosomal recessive

13

First trimester testing is performed between ______ and _________weeks and involves two parts

11.5 and 13.5

14

Types of genetic testing done during the firs trimester

*Nuchal translucency
*Maternal blood test of free or total beta hCG and PA PP- A (pregnancy associated plasma protein A)

15

The combination of the two test done in the first trimester are done to test for

85% of Down syndrome (trisomy 21), & trisomy 18 (Edward's syndrome)

16

Measures the fluid filled area at the back of the neck between 11.5 and 13.5 weeks

Nuchal translucency screening

17

In what plane is the Nuchal translucency screening done?

Sagittal

18

How is the Nuchal translucency measured?

The measurement is taken inner to inner

19

Nuchal translucency is normal if it is

less than 3mm

20

The __________ which is ____________ to the fetus should not be mistaken for increased nuchal translucency

Amnion, adjacent

21

If the Nuchal translucency is increased,

genetic testing of the fetus is performed

22

If the fetus has a normal Karyotype

the fetus should be screened for cardiac abnormality in the mid-to-late trimester

23

PA PP-A and beta hCG are produced by

trophoblastic tissue

24

Low levels of PA PP-A and beta hCG may indicate

abnormal implantation
poor placentation
risk of trisomy 21

25

An invasive test where a needle is placed within the uterine cavity via the cervix, and samples of the chorion or trophoblastic tissue, cells are obtained to evaluate for chromosomal abnormality

Chorionic villus sampling or CVS

26

Testing done in the second trimester known as the quadruple is made up of what tests?

1. Maternal serum alpha-fetoprotein, MS AFP
2. Human chorionic godadotropin, hCG
3. Unconjugated estriol or E3
4. Inhibin A

27

a glycoprotein which is produced primarily in the fetal liver. It crosses the placenta into the maternal serum and can easily be detected with a blood test called the maternal serum alpha-fetoprotein

Alphafetoprotein or AFP

28

When can AFP be evaluated

-Incorrect dates (patient is further along in the pregnancy than she thought) *especially if AFP is decreased
-Multiple gestations
-Open neural tube defects
-Abdominal wall defects
-Sacrococcygeal teratoma in the fetus
-Maternal fetal hemorrhage
-Placental Chorioangioma

29

Chromosome abnormalities

1. Fetal demise
2. Trisomy 21/ Down syndrome
3. Trisomy 18/ Edwards syndrome

30

Increased MS AFP
Increased beta hCG
Decrease in E3
Increase in Inhibin A

Trisomy 21/ Down syndrome

31

Decreased MS AFP
Decreased hCG
Decreased E3

Trisomy 18/ Edwards syndrome

32

If the ultrasound evaluation fails to establish a cause for abnormal quadruple screen test, then __________ is offered to the patient to evaluate amniotic fluid levels of AFP and for fetal chromosome Karyotyping

Amniocentesis

33

An invasive procedure whereby ultrasound is used to guide needle placement into the amniotic cavity

Amniocentesis

34

When is an Amniocentesis performed?

at around 16 weeks