Ch 49 Sonography of the 2nd and 3rd trimester Flashcards
(36 cards)
• Technical factors that may result in less than optimal studies?
–Fetal movement
–Fluid quantity
–Fetal position
–Maternal wall thickness or obesity
How many days does a pregnancy last?
Human pregnancy lasts 266 days + or – 10 days
• If conception occurs on day 14 from the LNMP the duration from the LNMP is?
280 days or 40 weeks
In reality what assessment of menstrual or gestational age is often not precise?
–Irregular menstrual cycles
–Birth control
–With a known menstrual date conception may occur from day 6 to day 27
When the LMP is unknown or when the patient has irregular menstrual cycles the estimated date of confinement (EDC) or due date is derived by the obstetrician or clinician using clinical parameters?
–Uterine size and growth
–Fetal heart ausculation
–Sonographic biometry before 26 weeks
–Ovulation indications
What does the gestational age estimate?
–Estimate of how long the patient has been pregnant
What are the clinical verification of pregnancy?
–Presence of hCG within the maternal urine or serum
–Quantitative levels of hCG
What does the rate at which hCG increases in early pregnancy may be predictive of obstetrical complications?
•Ectopic pregnancy
–Low levels increasing slowly
•Molar pregnancy
–High levels increasing rapidly
What predicts the risk of aneuploidy?
•Later in pregnancy hCG is one of the biochemical assays used to predict the risk of aneuploidy
A pregnancy is divided into trimesters; 1st trimester?
0 – 12 weeks gestation
A pregnancy is divided into trimesters; 2nd trimester?
13 ‐ 26 weeks gestation
A pregnancy is divided into trimesters; 3rd trimester?
27 ‐ 42 weeks gestation
A pregnancy is divided into trimesters; Postterm pregnancy?
> 42 wks gestation
What is calculated using Nagele’s rule?
EDC
Nagele’s rule: EDC and LMP?
–EDC = LMP – 3 months + 7 days –LMP = EDC + 3 months – 7 days
Gravidity; G?
–Number of pregnancies, including the present one
Parity; P?
–Reported using a numeric system that describes all possible pregnancy outcomes
–P is followed by four numbers in sequence
•P 0 0 0 0 represent?
1 –Full term deliveries
2 –Premature births and stillborns
3 –Early pregnancy loss or termination
4 –Living children
Example:
G4P2103?
–4th pregnancy –2 full term deliveries –1 premature birth –0 early pregnancy losses –3 living children
Example:
G4P2105?
–4th pregnancy –2 full term deliveries –1 premature birth –0 early pregnancy losses –5 living children
Example:
G4P2105?
If you see this you need to ask an additional question or two?
•What would those questions possibly be?
– Twins, triplets, quadruplets, etc
What is essential to the performance of obstetric sonography?
Recognizing normal fetal anatomy
A key to developing scanning expertise is to become?
Become organized and systematic in assessing the fetus, placenta, and amniotic fluid
•Scanning techniques
Steps to survey the uterine contents, what to determine?
Determine:
- Fetal position,
- Number (# of babies)
- Verify cardiac activity,
- Presence of uterine and placental masses
- Obvious fetal anomalies,
- Amniotic fluid assessment
- Rt and Lt side of the fetus
