Pregnancy And Prenatal Testing Flashcards
1st trimester
Day of conception - 12 weeks
When is the start of gestation?
First day of the last menstrual period
2nd trimester
13 - 26 weeks
3rd trimester
26 week - delivery
Conception
Used as an indication of development from the date the sperm fertilizes the ovum
Gestation
Used as an indication of fetal development from the last period
Ovulation
Ovum released from the ovary to fallopian tube
Zygote
Ovum that has been fertilized in the fallopian tube by sperm
Blastocysts
Cluster of 50-60 cells with a cavity to form the yolk sac. Goal of implantation into uterine wall
5 days past fertilization
Placenta
Functional surface between the mother and fetus that secretes hormones and growth factors into the mother with physiological effects
Embryo
Cluster of cells once implantation occurs
Organogenesis
Create organs by embryo, takes 10 weeks
Development at 10 weeks
Organs developed, heartbeat, regular arm and leg movement, 8cm long, 13 grams
Development at 2nd trimester
Rapid growth, moves freely, hiccups, can yawn, genitalia become visible and functionally release sex hormones
Development at 26th week
Most premature births can survive if sufficient prenatal care is available
Development at 3rd trimester
Fetus gains 200 g/week (7oz), eyes open and blink, practice breathing, sucking reflex at 34weeks
When does delivery occur?
38-42 weeks
What happens to progesterone and estrogen at delivery?
Progesterone will rapidly drop and estrogen will rise as progesterone drops.
Progesterone continues to increase throughout pregnancy to maintain pregnancy
Development in the last 4 weeks
Mainly for muscle development, building fat storage, practicing movements required for life after delivery
What happens to plasma volume during pregnancy?
Steadily increases 50-85%. Directly proportional to the weight of the fetus in the 3rd trimester
Renin-Angiotensin-Aldosterone System is ____ during pregnancy.
Activated
(underfilling of arteries and release of relaxin)
What happens to calcium in the mother’s body during pregnancy?
Decreases. The fetus needs free calcium, and if there is insufficient calcium in the mother’s circulation, calcium will be released from the mother’s bones.
As GFR increases, filtration of creatinine, uric acid, and BUN ___, causing a ___ in plasma levels
Increase
Decrease
How is hyperventilation compensated in the mother’s body?
Mild, fully compensated respiratory alkalosis
Why is the mother’s immune system altered during pregnancy?
To prevent an immune response from paternal antigens in fetus. Pro-inflammatory response is decreased
What is the purpose of (beta)HCG assessment?
Early detection of pregnancy?
What is the expected trend of HCG levels throughout pregnancy?
Doubles every 24 hours until 8th week, peak at 10th week, decreases until 16 weeks, stabile thereafter
HCG levels can take ___ to ___ days to return to normal post pregnancy
7 - 60 days
What can cause a false negative in point of care pregnancy testing?
Too early, dilute urine, hook effect for very high hCG levels
What can cause a false positive in point of care pregnancy testing?
Medications (aspirin, carbamazepine, methadone), sitting too long, untrained eye
Point of care pregnancy testing is a (qualitative/quantitative) test
Qualitative
T/F:
Hyperglycosylated hCG in early pregnancy is detected in point of care CLIA waived at home test
FALSE
Not detected in early pregnancy
T/F:
There is no reference range for pregnancy related quantitative maternal serum b-hCG
TRUE
But 20 is a common cut off for pregnancy
What can cause false positives in serum immunoassay methodologies?
Heterophilic ab, rheumatoid factors, IgA deficiency, chronic renal failure, end-stage renal disease, exogenous hCG consumed
What can cause false negatives in serum immunoassay methodologies?
Hook effect
T/F:
AFP can pass from placenta to maternal bloodstream
TRUE
What is the concentration trend of AFP?
Rise at the end of the first trimester and fall after 32 weeks
Where is AFP produced?
Yolk sac first and then parenchymal cells in the fetal liver
What is the significance of maternal AFP (MS-AFP) test?
Screening marker for fetal abnormalities, fetal distress, indicator of pregnancy health.
(General marker for spina bifida and anencephaly for the fetus and preeclampsia and risk of perinatal death for the mother)
What affects MS-AFP levels?
Age, body mass, ethnicity, gestational age
What is Multiples of Median (MoM)
(Mother’s AFP)/(Median of reference range)
Compares patient’s AFP serum to the median of the reference range. Helps overcome variable that an influence results.
What is the reference range of MoM AFP?
0.5 - 2.0 MoM
What can cause a false positive in MoM
Multiple pregnancy, incorrect calculation of fetal gestation, gestational diabetes, tobacco smoke exposure, lab techniques
Why would you perform fetal amniotic fluid AFP testing?
When MS-AFP is higher than expected and you aren’t finding an answer through ultrasounds. Be careful to avoid fetal or maternal contamination as blood will interfere.
Specimen types for AFP
Serum, Urine, or amniotic fluid
What is the predominant estrogen in pregnancy and where is it synthesized?
Estriol (E3) and it is synthesized in the placenta
What is E3 screening most used for?
Screening for trisomy 21 (Down’s syndrome) and trisomy 18 (Edward’s syndrome)
T/F:
The triple and quadruple screen test is used as a diagnostic test
FALSE
Screening purposes only
Pregnancy Associated Plasma Protein A (PAPP-A)
Valuable 1st trimester screening test. Low concentration in trisomy 13, 18, 21, and Turner syndrome
Progesterone
Important for establishing and maintaining healthy pregnancy. Steroid produced by placenta. Monitor in suspected high risk spontaneous/natural fetal abortion
Gestational diabetes (GDM) affects __% of all pregnancies
10%
Levels that define GDM (meet or exceed these levels)
Fasting:
1Hr:
2Hr:
3Hr:
Fasting: 95mg/dL
1Hr: 180mg/dL
2Hr: 155mg/dL
3Hr: 140mg/dL
Positive Fetal Fibronectin is indicative of what?
That the patient will likely go into labor within 7-14 days
Neural Tube Defects
One of the most common birth defects. It occurs wen the neural tube does not close completely
Spina Bifida
Occurs when fusion is not complete along the spinal cord of the developing fetus
Down Syndrome
Usually 3 copies of chromosome 21, 5% due to translocation
Maternal age severely ___ the risk of having a fetus with Down Syndrome
Increases
Trisomy 18
Occurs when the fetus has an extra copy of chromosome 18
Isoimmunization
Involves fetal hemolytic disorder. Mom is against baby
Isoimmunization most often occurs when mother is Rh ___ and is carrying a Rh ____ fetus
Mother: Negative
Fetus: Positive
Pre-Term delivery
Fetus is delivered earlier than the 37th week of gestation
What is the most common problem seen in pre-term delivery
Respiratory Distress Syndrome: a lack of pulmonary surfactant
Pre-Eclampsia
Hypertension, proteinuria, and edema in the 2nd and 3rd trimester that occurs in 5% of pregnancies. Only cure is delivery
Hyperemesis Gravidarum
“Morning Sickness”
70% of pregnancies. Wide range in severity
Ectopic pregnancy
Trophoblastic cells prematurely attaching to the lining of the fallopian tube instead of attaching to the uterine endometrium.
Must surgically remove
Analyte deficiency
Calcium deficiency during 2nd and 3rd trimesters
Relative iodine deficiency
