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Name the different sensitization routes for Rh isoimmunization
- Incompatible blood tranfusion
- Ectopic pregnancy
- Invasive procedures during pregnancy (e.g. amnio, D&C, cerclage)
- Any type of abortion
- Labour and delivery
What Ab titre is considered benign (for Rh)?
Ab titres < 1:16 (meaning Ab's not picked up after dilution of 1:16). If Ab titres > 1:16, require amniocentesis to determine the severity of fetal RBC hemolysis.
What test can be used to determine the extent of fetal-maternal hemorrhage?
Kleihauer-Betke test - fetal RBC's identified in maternal blood on a slide after treatment with acid solution
What is fetal hydrops?
Total body swelling of fetus
When do you give Rhogam?
- Give to all Rh -ve women in the following situations:
- at 28 weeks
- any invasive procedure in pregnancy
- within 72hrs after birth in Rh +ve fetuses
- with a postive Kleihauer-Betke test
- ectopic pregnancy
- antepartum hemorrhage
- any invasive procedure during pregnancy (e.g. amniocentesis)
What are the potential consequences of anti-Rh IgG?
- IgG antibodies developed my mom can cross the placenta and cause:
- fetal anemia (via hemolysis)
- fetal edema
- fetal ascites
- fetal hydrops
What percentage of women are carriers for GBS?
What are risk factors for GBS infection in neonates?
- Positive screen for GBS
- GBS bacteriuria (even if treated!)
- Maternal fever intrapartum
- ROM > 18hrs
- preterm labor (<37 weeks)
- previous child with GBS infection
What are the potential complications (in neonate) of a GBS infection?
Pneumonia, meningitis, sepsis
When do you screen for GBS status during pregnancy?
At 35-37 weeks (first vaginal, then anorectal swab)
What antibiotics would you use to treat a GBS +ve woman at time of delivery?
- Penicillin G 5 million U, then 2.5 million U Q4H until delivery
- If mild pen allergy (no risk for anaphylaxis), can use cefazolin 2g IV, then 1g Q8H
- If true pen allergy, use clindamycin (900mg IV q8h) or erythromycin (500mg IV q6h)
What are some indications for prenatal diagnosis for genetic disorder?
- Maternal age > 35
- Teratogenic exposure during current pregnancy
- Abnormal U/S
- Abnormal prenatal screening
- Past personal history/family history of genetic disorder
What are 3 indications for amniocentesis?
- Identification of genetic anomolies (done at 15-16 weeks)
- Determination of the L:S ratio (lecithin:sphingomyelin), if >2:1, RDS is less likely. (Done in T3)
- Determination of the level of bilirubin (as a measure of fetal RBC hemolysis)
What is the duration of each trimester?
- T1: 0-12 weeks
- T2: 12-28 weeks
- T3: 28-40 weeks
Describe the GTPAL format
- G - Gravida: Total number of pregnancies (including abortions, molar pregnancies, ectopics). Note that twins = 1 pregnancy
- (Parity - TPAL)
- T - Term: Number of term deliveries
- P - Preterm: Number of preterm (<37 weeks) deliveries
- A - Abortions: Number of abortions (loss of pregnancy < 20 weeks or fetus < 500g)
- L - Number of living children
What is Goodell's sign?
Softening of cervis (4-6 weeks)
What is Hegar's sign?
Softening of the cervical isthmus (6-8 weeks)
What is Chadwick's sign?
Bluish discoloration of the cervix and vagina due to pelvic vascular engorgement (6 weeks)
What is the B-hcg rule of 10's?
- 10 IU at time of missed menses
- 100,000 IU at 10 weeks (peak)
- 10,000 IU at term
Note: B-hcg is produced by the placenta and consists of alpha and beta subunits. Plasma levels double every 1-2 days.
B-hcg less than expected, possible causes?
- Wrong dates
- Ectopic pregnancy
B-hcg more than expected, possible causes?
- Wrong dates
- Molar pregnancy
- Trisomy 21
What can be seen on U/S during the following times?
1-Transvaginal at 5 weeks?
2-Transvaginal at 6 weeks?
3-Transvaginal at 7-8 weeks?
4-Transabdominal at 6-8 weeks?
- 1-Gestational sac
- 2-Fetal pole
- 3-Fetal heart
- 4-Intrauterine pregnancy
What cardiovascular changes can be expected during pregnancy?
- Increased CO/blood volume/HR
- Decreased PVR (thus decreased BP)
- Decreased venous return (due to uterus size compressing IVC), thus increased venous pressure (leading to varicose veins)
What respiratory changes can be expected during pregnancy?
- Decreased RV, FRC and TLC
- Increased minute ventilation (RR x TV)
- Increased O2 requirements
What GI changes can be expected during pregnancy?
- GERD (decreased LES tone, delayed gastric emptying -> these two due to progesterones effects). Also increased gastric pressure due to uterus.
- Gallstones (progesterone increased GB stasis)
- Hemorrhoids (decreased GI motility again due to progesterone)
What GU changes can be expected during pregnancy?
- Urinary frequency
- Increased incidence of UTI's and pyelonephritis
- Increased glucose in urine
What is Nagele's rule?
LMP + 7 days - 3 months.
If cycle > 28days, need to add these additional days to the formula above.
What investigations are necessary as part of the initial prenatal visit?
- CBC, blood group and type, Rh antibodies, Urine R&M / C&S (look for protein and bacteria), pap smear, culture for gonorrhea and chlamydia, bacterial vaginosis swab.
- Also need to screen for other infections (such as syphilis, herpes, etc).
List the timing of the prenatal visits
- Q4-6 weeks until 28 weeks
- Q2 weeks from 28 - 36 weeks
- Q1 week from 36 weeks until delivery
What should you assess at every visit?
- History of current pregnancy (fetal movements, any bleeding, any cramping, any leaking of fluid)
- Physical exam: BP, Weight, SFH, Leopold's maneuvers (T3) for position / presentation of fetus
- Investigations: Urinalysis (glucose, protein), fetal heart tones (starting at 12 weeks)
Where should you expect to find the uterus at 12, 20 and 27 weeks?
- 12 weeks: Top of uterus (fundus) located at syphysis pubis
- 20 weeks: Fundus located at umbilicus
- 27 weeks: Fundus located at sternum
Note: Between 20 and 27 weeks, SFH should be within 1-2cm of GA
How many fetal movements is considered normal (and in what time duration)?
< 6 movements in 2 hours is concerning. If this is the case, mother should move to quiet room, change position, drink juice and concentrate on counting babie's movements. If still < 6, contact MD.
What is a NST? What are its indications?
NST stands for Non Stress Test. It consists of looking at the fetal heart rate (FHR) for at least 2 accelerations of > 15bpm lasting at least 15 seconds over a 20 minute period. If none observed in 20 minutes, change position / stimulate baby, retry. If non-reactive, move to BPP.
What is a BPP?
- BPP stands for biophysical profile. It is performed when a non-reassuring NST is performed, or if there's any indication of fetal distress or utero-placental insufficiency. It consists of looking at 4 parameters:
- 1) AFV: Amniotic fluid volume (look for at least 1 fluid pocket of 2cm x 2cm)
- 2) Fetal tone: One occurence of limb extension followed by flexion
- 3) Fetal breathing movements: One episode of breathing lasting 30 seconds
- 4) Fetal limb movements: Three discrete movements
When is the dating U/S best done?
Between 8 - 12 weeks
When is the anatomical U/S best done?
Between 18-20 weeks GA
Which is more accurate for genetic testing - amniocentesis or chorionic villous sampling?
What advantages/disadvantages are there to doing CVS?
- Can be done earlier - 10 to 12 weeks (thus enables pregnancy to be terminated earlier if desired)
- Rapid karyotyping possible (48 hours)
- High sensitivity and specificity
- Disadv 1-2% risk of sponatenous abortion (vs 0.5% with amnio)
- Does not screen for oNTD (whereas amnio can)
- May see false -ves due to genetic mosaicism
Termination of pregnancy - What are the medical and surgical options?
- Medical<9 weeks:Methotrexate + misoprostol
- >12 weeks:Prostaglandins or misoprostol
- Surgical<12-16 weeks:D&C
- >16 weeks:Dilatation and evacuation
What are the potential complications of termination of pregnancy?
Hemorrhage, pain, uterine perforation, infection(endometritis), Asherman's syndrome (uterine scarring causing infertility/amenorrhea), retained products of conception
T/F: Iron requirements increase in pregnancy?
True! Need to provide pregnant woman with Fe supplementation, especially during 2nd and 3rd trimester
T/F: Folate deficiency anemia is not associated with Fe deficiency anemia?
False! It is associated with Fe deficiency anemia. Folic acid is necessary for closure of the neural tube and all women should get at least 0.4mg pre (1-3 months) and during pregnancy (especially T1). Women with past history of oNTD or diabetes or on anti-epileptics should use 4mg per day.