Antepartum care Flashcards
Causes of bHCG less than expected
Ectopic pregnancy
Miscarriage
Inaccurate dates
Causes of bHCG greater than expected
Multiple pregnancy
Molar pregnancy
Trisomy 21
Inaccurate dates
When is gestational sac visible on U/S
4-5 weeks
What is Naegele’s rule for calculating EDD?
1st Day of LMP + 7 days, - 3 months + 1 year
add days if cycle >28d long
5 questions to ask to calculate EDD
First day of LMP? Was this period normal in all respects? Menstrual cycle regular? Menstrual cycle length? Are you using contraception?
What gestation is most accurate for calculation of EDD by ultrasound
7-10 weeks (EDD calculated +/- 3 days)
How much folic acid should a woman take if pregnant?
400ug until 12 weeks gestation
5mg if previous pregnancy affected by neural tube defects or FHx
Virus/bacteria exposures tested for on 1st visit bloods
Rubella titre Syphilis serology Hepatitis B Hepatitis C HIV
When is morphology scan done
18-20 weeks gestation
If mother Rh-, when is prophylactic anti D given?
625IU given at 28 and 34 weeks and post delivery
In what other circumstances would you give anti-D
Threatening miscarriage ectopic pregnancy D&C Amniocentesis Termination of pregnancy Antepartum haemorrhage Abdominal trauma External cephalic version
How much anti-D do you give in the first trimester
250IU
When do you do a OGTT in low risk women?
28 weeks
When do you do a lower vaginal swab for Group B streptococcus
36 weeks
What glucose levels are diagnostic of gestational diabetes
Fasting venous glucose ≥ 5.0 mmol/L
2h venous glucose ≥ 6.7 mmol/L
What risk factors does a woman need to have to be “high risk” for GDM?
Previous GDM Maternal age ≥ 40 BMI ≥ 35 Previous baby >4.5kg or >P90 Polycystic ovarian syndrome
What are the 3 screening tests for fetal aneuploidy
- First trimester combined
- Second trimester
- Non-invasive prenatal testing (NIPT)
What are the 2 diagnostic tests for fetal aneuploidy
- Chorion villus sampling
2. Amniocentesis
What is measured in combined first trimester screening test?
- free bHCG
- PAPP-A (pregnancy associated plasma protein)
- Nuchal translucency U/S at 11-13+6 weeks
What is measured in second trimester screening (when GA 14-20+6)
- Alpha fetoprotein
- bHCG
- Unconjugated estriol
What does the NIPT involve?
Maternal plasma used to collect cell-free fetal DNA
Can assess T18. T21, T9 plus sex hormones
Done >10 weeks
When is chorion villus sampling done?
10-14 weeks
When is amniocentesis done?
> 14 weeks
What is the risk of miscarriage with the 2 diagnostic tests?
CVS: 0.5-1%
Amniocentesis: 0.5%
