pregnancy tests Flashcards
(39 cards)
prenatal care of 1st trimester
patients should be seen every 4-6 wks:
- 11-14 wks: US to confirm gestational age + check nuchal translucency
- fetal heart sound at the end of the trimester
- blood tests, pap tests, pap smear, gonor/chl tests
- 1st trimester screening may be offered
what is 1st trimester screening
noninvasive evaluation to identify risks of ch abnormalities –> it is a combination of blood tests + US that evaluates the fetus for possible Down syndrome
what is 2nd trimester screening
- screen for genetic + congenital problems (triple or quad screen at 15-20 wks
- auscultation of fetal heart rate
- 16-20 wks: quickening (feelling fetal movement for the first time) - multiparous women earlier
- 18-20 wks routine US for fetal malformation
triple vs quad screen
triple: maternal serum alpha fetoprotein (MSAFP), β-MCG, estriol.
quad: adds inhibin A
increase in MSAFP may indicate … / how to increase the sensitivity of the test
- dating error
- neutral tude defect
- abd wall defect
The addition of beta-HCG estriol and inhibin A helps increase the sensitivity of MSAFP test
what is 3rd trimester screening
- visits are every 2-3 wks until 36 wks
- after 36 wks, visit every week
- blood count at 27 wks
- glucose load at 24-28
- test for microorganisms in 36 wks
third trimester testing - complete blood count
27 wks: if Hb under 11 –> iron orally (with stool softeners)
third trimester testing - test for microorganisms
36 wks: Cervical culture for Chlamydia + gonorrhea –> treatment if positive
rectovagina culture for group B strep -> prophylactic antibiotic during labor
other screening test - types
- Chorionic villus test
- amniocentesis
- fetal blood sampling
Chorionic villus test - when and indications
at 10-13 wks in:
- advance maternal age
- known genetic disease in parent
Chorionic villus test - technique / purpose
catheter into intrauterine cavity to aspirate chorionic villi from placenta (tranabdominally or transvaginally) –> obtains fetal karyotype
amniocentesis - when and indications
after 11-14 wk:
- advance maternal age
- known genetic disease in parent
amniocentesis - technique / purpose
needle transabdominally into the amniotic sac and withdraw amnitoci fluid –> obtains fetal karyotype
fetal blood sampling - indications
done in patients with Rh isoimmunization and where a fetal CBC is needed
fetal blood sampling - technique / purpose
needle tranabdominally into the uterus to get blood from the umbilical cord –> percutaneous umbilical blood sample
mother screening for Rh incompatibility
Rh antibody screening (during 1st prenatal visit)
- –> no further screening
- Rh (-) –> antibody titer
a. if sensitized (have antibodies)–> further monitor
b. if unsensitized (no antibodies) –> repeat at 28 wks and if still (-) give Rhogam (anti-D) as indicated
- At delivery: if newborn is Rh (+) –> again Rhogam to mother
hemolytic disease of newborn - presentation and mechanism
- fetal anemia –> extramedullaty RBCs production (liver + spleen)
- hemolysis –> increased heme + bilirubin (neurotoxic)
- high fetal cardiac output
some scenarios where fetal blood cells may cross into the mother’s blood (sensitising the mother)
- amniocentesis
- abortion
- vaginal bleeding
- placental abruption
- delivery
further monitor in Rh (-) sensitized pregnant
antibody titer via indirect antiglobulin test:
- the patient is consedered sensitized if she has a titer level more than 1:4
- if less than 1:16 –> no further treatment / but if reaches 1:16 at any point during pregnancy, serial amniocentesis should be done (evaluation of fetal bilirubin level)
pregnant’s antibody titer for Rh equals or more than 1:16
–> ….
do 1st amnioncentiesis at 16-20 wks:
- fetal cells Rh (-) –> manage like normal pregnancy
- Rh (+) –> amniocentesis evaluated under spectrophotometer (to evaluate bilirubin):
a. low bilirubin –> repeat amniocentesis in 2-3 wks
b. medium –> repeat in 1-2 wks
c. high –> fetus is anemic –> do percutaneus umbilical blood sample (for Hct) –> low Hct –> perform intrauterine transfusion
fetal testing after 32 weeks
- 32-36: weekly nonstress test (NST) for fetal well being and US (fetal size)
- more than 36: twice weekly testing: 1 NST and 1 biphysical profile (amount of amniotic fluid + fetal well being)
- 37 lecithin / sphingomyelin (assess lung maturity, if ok deliver)
- 38-39: no test / labor induction
Indications for prophylactic administration of anti-d immune globulin for Rh(D) negative patients
- at 28-32 weeks
- less than 72 h fter delivery of Rh (+) infant
- less than 72 hours after spontaneous abortion
- ectopic pregnancy
- threatened abortion
- hydatidiform mole
- chorionic villus sampling, amniocentesis
- 2nd + 3rd trimester bleeding
- external cephalic version (?)
karyotyping of fetal tissue after 1 spontaneois miscarrieage
not indicated –> considered after recurrent pregnancy or loss in the 2nd trimesterb
when to give anti-D (time) / dose
28 weeks and within 72 h of delivery
- a standard dose of anti-D immune globulin at 28 wks in uncomplicated pregnancy is adequate/ however if the patient developed placental abruption earlier in pregnancy, the Kleihauer-Betke test should performed to determine whether a higher dose is indicated for postpartum
