Prenatal Testing Flashcards
What is the goal of prenatal testing?
Identify women at ↑ risk of medical complications, pregnancy complications, or fetal abnormalities
What is the most common chromosome abnormality?
- Trisomy 21
2. Screening detects up to 95 % of pregnancies affected by Down syndrome
What are prenatal testing programs based on?
Prenatal screening programs based on maternal serum & USN testing
What routine labs are preformed during the first prenatal visit?
- 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
What routine labs are preformed during the 28 wk prenatal visit?
- CBC
- GTT
- Repeat Ab titers if given RhoGam
A. Prevents erythroblastosis fetalis - Vaginal Cx for Group B Strep
What other prenatal tests may be performed?
- Genetic studies
A. Down Syndrome, Trisomy 18
What other prenatal tests may be performed for at-risk women?
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
What is chorionic villus sampling? How is it performed?
- 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
When is chorionic villus sampling (CVS) performed?
- Performed during 1st trimester
- After 10 weeks
- False (-) rate 0.03%
What are the indications for CVS?
- Maternal age > 35 yr
- Previous child w/ chromosome abn
- Pt or father of baby w/chromosomal abn
- FH chromosomal abn
What are the advantages of CVS?
- Able to perform in 1st trimester
2. Preliminary results w/in 48 hrs
What are the disadvantages of CVS?
- Cannot be used for AFP test
2. Spontaneous abortion risk slightly > amnio
What are the complications from CVS?
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
What is the Nuchal translucency screening test?
- AKA nuchal fold scan
- USN measurement of nuchal space
- Screens for Trisomy 13, 18, 21 & Turner Syndrome
A. Nuchal translucency is reduced/thicker?
When is nuchal translucency screening test performed?
Performed @ 11-13 weeks
What is trisomy 13 and 18?
- Severe mental retardation & abnormal organs in every body system
- Most die by age 1
What is trisomy 21?
- Down Syndrome
A. Most common chromosome abnormality in humans