Prenatal Testing Flashcards
1
Q
What is the goal of prenatal testing?
A
Identify women at ↑ risk of medical complications, pregnancy complications, or fetal abnormalities
2
Q
What is the most common chromosome abnormality?
A
- Trisomy 21
2. Screening detects up to 95 % of pregnancies affected by Down syndrome
3
Q
What are prenatal testing programs based on?
A
Prenatal screening programs based on maternal serum & USN testing
4
Q
What routine labs are preformed during the first prenatal visit?
A
- CBC
- ABO & Rh screen
- Coombs test
- Hep B screen
- RPR (rapid plasma reagin): syphiliis
- Rubella Titer
- Varicella Titer
- CF screen
- HIV screen
- UA
- Urine C&S
- Pap smear
- Chlamydia Screen
- Group B Strep
5
Q
What routine labs are preformed during the 28 wk prenatal visit?
A
- CBC
- GTT
- Repeat Ab titers if given RhoGam
A. Prevents erythroblastosis fetalis - Vaginal Cx for Group B Strep
6
Q
What other prenatal tests may be performed?
A
- Genetic studies
A. Down Syndrome, Trisomy 18
7
Q
What other prenatal tests may be performed for at-risk women?
A
1. Thyroid function studies A. Abn. neurologic development risk in mom w/hypothyroidism 2. Genetic conditions A. CF B. Thalassemia
- GC, TB, toxoplasmosis, Hep C, BV, trichomoniasis, HSV
8
Q
What is chorionic villus sampling? How is it performed?
A
- Procedure for prenatal diagnosis of genetic disorders
- Small samples of placenta obtained for chromosome or DNA analysis
A. Transcervical into placenta
B. Transabdominal into placenta
9
Q
When is chorionic villus sampling (CVS) performed?
A
- Performed during 1st trimester
- After 10 weeks
- False (-) rate 0.03%
10
Q
What are the indications for CVS?
A
- Maternal age > 35 yr
- Previous child w/ chromosome abn
- Pt or father of baby w/chromosomal abn
- FH chromosomal abn
11
Q
What are the advantages of CVS?
A
- Able to perform in 1st trimester
2. Preliminary results w/in 48 hrs
12
Q
What are the disadvantages of CVS?
A
- Cannot be used for AFP test
2. Spontaneous abortion risk slightly > amnio
13
Q
What are the complications from CVS?
A
1. Fetal loss A. 0.7% w/in 14 days B. 1.3 % w/in 30 days C. 2% for loss anytime during pregnancy 2. Limb defects 3. Failure of obtaining sample 4. Vaginal bleeding 5. Chorioamnionitis 6. Fetomaternal hemorrhage
14
Q
What is the Nuchal translucency screening test?
A
- AKA nuchal fold scan
- USN measurement of nuchal space
- Screens for Trisomy 13, 18, 21 & Turner Syndrome
A. Nuchal translucency is reduced/thicker?
15
Q
When is nuchal translucency screening test performed?
A
Performed @ 11-13 weeks
16
Q
What is trisomy 13 and 18?
A
- Severe mental retardation & abnormal organs in every body system
- Most die by age 1
17
Q
What is trisomy 21?
A
- Down Syndrome
A. Most common chromosome abnormality in humans
18
Q
What is trisomy 21 asst with?
A
- Delay in cognitive ability
- Delay in physical growth
- Specific facial characteristics
A. Low set ears
B. Macroglossia
C. Brushfield spots
D. ↓ Muscle tone - Single palmar crease, short fifth finger that curves inward
- Widely separated first and second toes and increased skin creases
19
Q
What are the characteristics of turner’s syndrome?
A
1. Only affects females A. Short stature B. Webbed neck C. Edema of hands & feet D. Skeletal abnormalities E. Premature ovarian failure F. 1/3 w/coarctation of aorta
20
Q
What are the indications for nuchal translucency screening test?
A
- Maternal age > 35 yr
- Previous child w/ chromosome abnormality
- Patient or father of baby w/ chromosomal abnormality
- FH chromosomal abnormality
21
Q
When is the quadruple screen performed?
A
- 15-18 Weeks Gestation (can be extended to 22 wks)
2. 16th -18th weeks most accurate
22
Q
What is included in the quadruple screen?
A
- Alpha fetoprotein (AFP)
- Human Chorionic Gonadotropin (hCG)
- Unconjugated estriol
- Inhinbin A levels
23
Q
What is alpha fetoprotein? When is it increased?
A
- Major circulating protein in fetus
- Inc level in neural tube defects
A. Spina bifida
B. Anencephaly
C. Myelomeningocele
24
Q
What is hCG? When is it increased?
A
- Produced by placenta
2. Inc levels in Trisomy 21
25
What is unconjugated estriol? When is it decreased?
1. Produced by placenta & fetal liver
| 2. Dec levels in Trisomy 21
26
What is inhibin A? When is it decreased?
1. Produced by placenta
| 2. dec levels in Trisomy 21
27
What are the types of spina bifida?
1. Occult
2. meningocele
3. Myelomeningocele
28
What do you do if the quadruple screen is abnormal?
1. Repeat AFP
2. USN w/detailed exam of fetal anatomy
3. Amniocentesis
29
Define amniocentesis
1. Withdrawal of amniotic fluid via transabdominal approach
| 2. Evaluates fetal health
30
What does the amniotic fluid contain?
Urine, secretions, exfoliated cells
31
When is the amniocentesis usually performed?
15-17 weeks gestation
32
What are the indications for amniocentesis?
1. Maternal age > 35 yr
2. Prenatal genetic screening
A. Down Syndrome
B. Trisomy 18
C. Spina bifida
-Usually performed in conjunction w/ serum AFP
3. Assessment of fetal lung maturity
A. 32-38 weeks gestation
4. Previous child w/ chromosome abn
5. Pt or father of baby w/ chromosomal abn
6. FH chromosomal abn
7. Neural tube defect risk
8.Abnormal triple screen
33
What are the advantages of amniocentesis?
1. Spontaneous abortion risk less than chorionic villus sampling
2. Amnio greater than CVS in range of genetic testing
34
What are the potential complications of amniocentesis?
1. Cramping
2. Spotting
3. Loss of amniotic fluid
4. Fetal injury
A. Orthopedic malformations
B. Lung problems
35
When is an ob usn performed?
1. Can be performed as early as 5-6 weeks gestation or as late as 40 + weeks gestation
2. Early pregnancy
A. Can detect fetal heart rate 5-6 weeks after LMP
36
What are the indications for ob sonogram?
1. Detects multiple fetus’
2. Helps determine EDC
3. Checks fetal viability
4. Correlates fetal growth w/gestational age
5. Checks placenta status & location
6. Evaluate vaginal bleeding
7. Check amniotic fluid levels
8. Correlate w/ abnormal ↑ AFP
37
What is the ob usn used for in late pregnancy?
1. Used to monitor fetal well being
| A. Biophysical profile/BPP
38
What are the parameters for BPP?
```
1. BPP has 5 parameters
A. Non stress test
B. Amniotic fluid level
C. Gross fetal movements
D. Fetal heart tones
E. Fetal breathing
```
39
What is the handheld doppler USN used for?
1. Handheld doppler USN (Doptone)
| A. Assess fetal heart tones from ≥ 10-12 weeks gestation
40
What is a non-stress test? What is it used for?
1. Doppler monitoring w/external stress gauge for uterine contractions
A. Used near term to determine fetal well being
B. Used to assess risks for those w/ pre-existing medical conditions & preg w/ complications
41
What is the normal fetal hr?
Normal (baseline) fetal HR 120-160 bpm
42
What is a normal (non-reactive) non-stress test?
1. Requires 2 accelerations of fetal HR in 20 min
A. HR must ↑ by 15 bpm from baseline
B. Must last 15 secs
2. No decelerations noted
43
What is an abnormal (reactive) non-stress test?
1. Dec in fetal HR (decelerations) of 15 bpm
A. Lasting > 15 secs
OR
B. Slow return to baseline
2. Persistent late decelerations after peak of contraction warrant intervention
44
How do you break abnormal news to expecting parents?
1. In the event of abnormal test results:
A. Inform both parents ASAP in person
B. Avoid using value judgments, such as "I'm sorry" or "Unfortunately, I have bad news," when starting conversation
C. Provide up-to-date verbal & written info, including support groups
D. Refer to other specialists (medical geneticists, genetic counselors, cardiologists, neonatologists, pediatric surgeons
E. Couples have several options (continue pregnancy, termination, adoption), which should be discussed w/ sensitivity to their beliefs & values
