Ch 53 Powerpoints

Question 1

Chromosomes

Answer 1

Each cells holds genes
An error in number or structure of the chromosomes causes an abnormality
Normal cell has 46 chromosomes of two pairs of 23

Question 2

Aneuploid

Answer 2

A cell that has an abnormal number of whole chromosomes

There may to too may or too few

Question 3

Diploid

Answer 3

A cell having the normal pair of each chromosome. Normal cells are diploid, with the exception of the gametes

Question 4

Haploid

Answer 4

A cell having only one member of each pair of chromosomes

Question 5

Monosomy

Answer 5

A cell having only one of an individual chromosome

Question 6

Mosaic

Answer 6

A situation in which some cells have an abnormal number of chromosomes, while others do not

Question 7

Triploid

Answer 7

A cell having 3 times the normal haploid number

Question 8

Trisomy

Answer 8

A cell having three copies of an individual chromosome

Question 9

Anomalies

Answer 9

A structural feature that differs from the norm

EX: agenesis of the corpus callosum in which there is a congenital abscense of an important midline brain structure

Question 10

Syndrome

Answer 10

A group of clinically observable findings that exist together and allow for classification
These signs and symptoms are linked to each other in some way
Chromosomal abnormalities often exist when there are multiple defects

Ex: Down Syndrome has clinically identifiable signs such as flat facial profile and a transverse crease in the palm of the hand

Question 11

Malformation

Answer 11

A structural abnormality that results from unusual development

EX: Dandy-Walker malformation a congenital brain malformation that is thought to be caused by a developmental deviation in the roof of the fourth ventricle

Question 12

Triple screen

Answer 12

A maternal blood test in the second trimester for detection unusual levels of certain proteins or hormones with chromosomal
Triple test has a 60% chance of detecting Down syndrome
abnormalities

Question 13

Triple screen- Three lab Values

Answer 13

AFP, estriol, and hCG
AFP- produced in the yolk sac and fetal liver
Estriol and hCG are produced by the placenta

Question 14

Quadruple screen

Answer 14

The triple screen plus two proteins can be monitored which are produced by the placenta
PAPP-A: pregnancy associated plasma protein A
Dimeric inhibin A

Question 15

Fetal Karyotyping and Genetic Testing

Answer 15

Advanced maternal age is considered to be 35 years of age or older
Patients with advanced maternal age have a greater risk of having an abnormal pregnancy of pregnancy failure
Fetal karyotyping is an analysis of fetal chromosomes and frequently recommended

Question 16

Three main procedures for obtaining material for fetal karyotyping

Answer 16

chorionic villi sampling, amniocentesis, cordocentesis

Question 17

Transvaginal chorionic villi sampling

Answer 17

Earliest procedure
Small amount of chorionic villi is obtained for chromosomal testing
Performed TA or TV 10-12 gestational weeks

Question 18

Transabdominal chorionic villi sampling

Answer 18

Under ultrasound guidance, a needle or plastic catheter is placed into the placental mass for the aspiration of trophoblastic cells

Fetal loss rate is approx 0.8%

Question 19

Amniocentesis

Answer 19

Used for genetic purposes at around 15 weeks
Performed transabdominally with ultrasound guidance

Physician inserts a 20 to 22 gauge needle through the abdomen and into the anmiotic sac to remove amniotic fluid

The most common side effects are uterine contractions and cramping

Rarely patients experience vaginal spotting, amniotic fluid leakage or amnionitis

Fetal loss rate 0.5%
2-3 weeks for complete analysis of the fluid

Question 20

Cordocentesis

Answer 20

Also referred to as percutaneous umbilical cord sampling (PUBS)

Performed TA at 17 weeks

A needle is placed through the maternal abdomen and into the umbilical cord at its insertion point into the placenta

A sample of fetal blood is removed

Fetal loss rate of 1%

Allows for rapid detection of chromosomal anomalies, requires only 48-72 hours for analysis