Genetic Screens Flashcards
What is the purpose of the prenatal screen?
Define the risk of a genetic disease in a low risk population
Does screening r/o a disease?
no
What is the difference between a diagnostic test and a screening test?
A screening test does not confirm or r/o a disease, but assesses the risk that a child may have a genetic disease
What are the three major genetic screens done?
T21, T18, and T13
What are the three biochemical markers tested for in the 1st trimester?
- hCG
- PAPP-A
- Nuchal translucency
What does nuchal translucency measure? When can this be measured
The size of the fluid at the back of the fetal neck that can bee seen at 10-14 weeks
What is the PAPP-A test?
Pregnancy associated plasma protein
What is the sensitivity of US and markers in the 1st trimester for Down syndrome? False positive rate?
85% sensitive
5% false positive
If there is an increased risk of aneuploidy with the 1st trimester screen, what is offered?
Genetic counseling, and diagnostic CVS or amniocentesis
What is the advantage of the 1st trimester screen?
Decisions can be made regarding continuing the pregnancy, if necessary
How early can CVS (chorionic villus sampling) be performed? What is done with this procedure?
As early at 10 weeks
-Needle is passed through the cervix into the chorion, and sample is gathered
How early can amniocentesis for genetics be performed? What is done with this procedure?
- 15-20 weeks
- needle passed through SQ tissue of mom into uterus/amnion, to gather skin samples for karyotyping
When can percutaneous umbilical blood sampling be performed?
20 weeks
What are the complications with amniocentesis?
- Pregnancy loss
- Break water.
Why is amniocentesis particularly important for 35 yo mothers?
Risk of diagnosing disorder = risk of having disorder
How do you get blood sample from a fetus (for typing/screen and/or karyotyping)? When is this performed?
- Percutaneous umbilical blood sampling
- After 20 weeks
Can US be used alone for aneuploidy?
Yes
If US is performed alone, what are the signs that may signal increased risk for chromosomal abnormality? (2) What should be done if these are detected?
Structural malformation of a major fetal organ or structure, OR finding 2+ minor malformations
Genetic testing of the fetus regardless of maternal age or parental karyotype
What are the components of the quad screen that can be done to confirm karyotypes?
- MSAFP
- Estriol
- hCG
- Inhibin A
When is US for anatomy performed?
22 weeks (2nd trimester)
Should women who have had 1st trimester screening for aneuploidy, undergo 2nd trimester screening? Why?
No–false positives,
When is 2nd trimester screening performed?
15-20 weeks
What is the relation between maternal AFP and T21?
Low AFP increases risk for T21
What is the sensitivity of T21 with the quad screen?
80%
What is integrated screening?
Results of both 1st and 2nd trimester screen and US combined to increase the ability to detect Down syndrome–these results are withheld until both tests are completed?
What is the sensitivity of the integrated screen?
94-96%
What are the two genetic cancer screens that are commonly obtained in ob/Gyn?
- BRCA1 and 2
- HNPCC
The most important initial step in identifying women at high risk for hereditary cancers is through what?
Family history
What FMHx is concerning for gyn cancer? (4)
- 1st degree relative
- young ages (less than 50)
- CA in multiple generations
- Many CAs in one individual
What is Fitz-hugh-curtis syndrome?
Adhesions between the liver and the diaphragm d/t PID spread
If a woman tests positive for the BRCA mutation, what should be done? (2)
- Increased screening (e.g. MRI in addition to annual mammogram)
- Risk reduction surgery
What is HNPCC? Inheritance pattern?
AD defect in DNA mismatch repair, that increases the risk for colon and endometrial CA
What are “variants of undetermined significance” in terms of genetic testing?
Gene that is found, but is of uncertain significance–if these are later found to be at an increased risk, then she will be contacted
What is Lynch A (type I ) at increased risk for?
increased risk for colorectal and endometrial CA
What is Type B (Lynch II) at increased risk for?
type A + ovarian, gastric, and pancreatic
What is the puerperium?
First 6 weeks after delivery, including time in the hospital
What are the vaccines that are updated in the hospital after delivery?
- MMR
- TDaP
- flu
Why do postpartum women need good breast support?
Breasts will engorge until painful
What is the appropriate hormonal birth control in recently postpartum women? Why?
Progesterone, since estrogen will decrease lactation
Why should oral contraceptives, as well as sexual intercorse, be done a few weeks later after being postpartum, instead of right after birth?
Risk for VTE
What are the common complications in the puerperium?
- wound infx/separation
- Endomyometritis
What is a dehiscence vs separation?
Dehiscence is when the fascia pulls apart, whereas in wound separation there is no fascial disturbances
What is endomyometritis?
Infection of the endometrium following pregnancy
How common are UTIs postpartum
Common
What are the 5 B’s of the immediate postpartum period?
- Brain (depression)
- Breast
- Bladder
- Bleeding (lochia)
- Birth control
What is the incidence of postpartum depression?
5-25%
How quickly does postpartum depression resolve?
7 months if untreated
How long do the “baby blues” last for?
10 days ish
What is the diagnostic criteria for postpartum depression? (start, end)
Onset within 4 weeks postpartum, and lasting up to 7 months
How long should pelvic rest postpartum last?
6 weeks
Combination OCPs should not be started until at least how many weeks postpartum?
3 weeks
True or false: a personal h/o ovarian cancer is a qualification to receive genetic testing for BRCA-1?
True
1 family member dx with breast, ovarian, colon or uterine CA under what age qualifies one to receive genetic screening?
45
2 family members dx with breast, ovarian, colon or uterine CA, and 1 dx under what age qualifies one to receive genetic screening?
50
What number of family member diagnoses at any age is needed to qualify for genetic testing?
3
Triple negative breast cancer under what age qualifies for genetic screening?
60
True or false: a family h/o of 1 male breast cancer qualifies for genetic screening
True
What is Lochia? How long does this last for?
the vaginal discharge after giving birth (puerperium) containing blood, mucus, and uterine tissue. Lochia discharge typically continues for 4 to 6 weeks after childbirth.
