O&G JC109: Can We Get Married? Pre-marital, Pre-pregnancy And Pre-natal Counseling Flashcards
Role of doctors in pregnancy
- Having a safe and healthy pregnancy, from conception to birth
- ↑ chance of having a healthy child
- ↓ chance of having adverse pregnancy outcome
- Understand available **prenatal screening + **diagnostic tests
Pre-marital + Pre-pregnancy counselling
Objective:
- Detect + assess any specific healthy problems in the woman / her partner that may be relevant —> managed prior to pregnancy
- Obtaining general advice about optimising personal health care + lifestyle
Timing:
- Appropriate whether the reproductive-aged patient is currently using contraception / planning pregnancy
- As health status / risk factors can change over time —> pre-pregnancy counselling should occur ***several times during a woman’s reproductive lifespan
Outline of counselling
- Reproductive risks
- Maternal
- Fetal - Risk identification
- Options for at-risk couples
- Counselling concerns
- Reproductive risks
Maternal:
1. Pre-existing medical conditions
- effect on pregnancy + fertility
- ***Pregnancy-related complications
- anticipate / precautions need to be taken - Operative risk
- Psychosocial problems
- e.g. socioeconomic problems
Fetal:
1. ***Growth problems
- maternal / fetal cause
- e.g. growth restriction —> caused by HT (early onset) of mother (lead to impaired placental blood flow to fetus) / syndrome or infection cause of fetus
- e.g. macrosomia —> GDM (suboptimal control) of mother / syndrome cause of fetus
- ***Congenital anomalies
- chromosomal / genetic
- structural (easier to identify e.g. using USG)
- functional (e.g. intellectual disability, harder to identify before birth) - Infection
- via placenta - Birth trauma
- Risk identification
Approach:
1. History taking
2. P/E
3. Screening tests
History taking
- Age (younger couples lower risk of chromosomal aneuploidy ∵ meiotic risk ↑ with advanced maternal age)
- Ethnicity (e.g. Sickle cell disease more common in African, Cystic fibrosis more common in caucasians)
- Consanguinity
- ↑ chance of offspring having **AR disorders if couples carry same genetic conditions, ↑ chance of multi-factorial disorder ∵ share same genetic + environmental exposure
- ↑ chance of **structural abnormality, **developmental delay, **autism spectrum disorder - Family history of congenital anomalies / chromosomal / genetic disorders / intellectual abnormality
- if high risk of a chromosomal / genetic disorder based on family history, referral to **pre-pregnancy genetic counselling by specialist is preferred to allow more reproductive options
- **3 generation pedigree —> identify whether AD / AR / X-linked
—> AD: 50% offsprings affected
—> X-linked: carrier mother to boy - Medical history
- discussion on how medical condition may **affect / **be affected by a pregnancy (by physiological / hormonal changes during pregnancy)
- stabilisation of pre-existing medical condition
- multi-disciplinary pre-pregnancy planning for complex medical disorders - Drug history
- review current medications including OTC on appropriateness + teratogenic potential
- may need adjustment of medication (switch to safer medication) prior to pregnancy to optimise disease control + minimise teratogenic risk
- drug allergy - Surgical history
- may affect mode of delivery - Occupation
- potential exposure to teratogens at work
- social background - Lifestyle, Risk of STI, Intimate partner violence
- Smoking, alcohol, substance use
- should be stopped before conception
- ***no known safe level of alcohol consumption during pregnancy
- considered for both parents when relevant - Nutrition
- well-balanced diet
- weight management —> do before conception (do NOT do weight reduction during pregnancy)
- peri-conceptional **folic acid supplementation (strong evidence ↓ risk of pregnancy with neuro-tube defects)
(*Folate supplement
- 0.4 mg/day (Felix Lai)
- 5 mg/day: previous infant with neural tube defect, DM patients, patients on anti-epileptic drugs (Felix)) - Vaccinations
- **Hep B, **Rubella, **Varicella immunisation can be considered again for women with incomplete immunity
- Seasonal influenza vaccination in pregnancy is **safe (Ig can also be passed to fetus —> offer protection to baby as well) - Travel + environmental risks
- ↓ chance of infection (e.g. Zika virus) - Obstetrics history (+ explore underlying cause)
- congenital anomalies
- stillbirth, neonatal death
- recurrent pregnancy loss
- grand multiparity
- difficulty delivery, birth trauma
- assisted reproduction: reason, any pre-implantation genetic testing (PGT) done, donor egg etc.
P/E
- General examination
- BP
- BMI (underweight + overweight) - Auscultation of heart sound
- Breast examination
- Abdominal examination
- Pelvic examination
- Cervical screening
- +/- Other tests as indicated
Screening in Antenatal care: What do we screen for? (SpC OG + Revision)
Maternal:
1. General health including anaemia
- Pallor
- Hb at booking
- Common infections (HBV, HIV, VDRL, Rubella, GBS)
- Common pregnancy complications: GDM, Hypertension
- GDM: Risk factor, Spot glucose, OGTT screening
- Gestation HT: Baseline BP (1st visit, ideally before 20 weeks), BP each subsequent visit, Urine albumin
Fetal:
1. Incorrect gestational age
- LMP
- Uterine size
- USG estimation (most accurate)
- Multiple pregnancy
- History: ovulation induction, assisted reproduction, maternal family history, exaggerated symptoms of pregnancy
- P/E: uterus larger than date, multiple fetal poles, multiple fetal heart sounds
- USG (earliest and most reliable) - Congenital abnormalities (Structural, Chromosomal)
- History: family history, previous abnormal babies, maternal disease (e.g. GDM, SLE), teratogenic drugs / irradiation, infection
- USG (18-20 week) detects 70% of major fetal abnormalities - Abnormal growth
- SFH measurement
- USG only for confirmation of suspicion - Abnormal lie and presentation
- Before 32 weeks and not in labour, no clinical significance
- Significant if in labour
- If not in labour, investigate / manage if
—> Transverse lie after 32 weeks, exclude placenta praevia, poly/oligohydramnios, other pelvic mass
—> Breech after 36 weeks, consider ECV / Elective C-section if no cause found
***Pre-pregnancy Screening tests
- CBP
- Hb
- MCV (part of antenatal thalassaemia screening programme) - Blood group, Rh factor
- Infection
- VDRL
- Hep B
- Rubella Ab
- HIV Ab
- STD (if high risk history / positive for one STD (SpC Revision))
(- CMV, Toxoplasma not routinely done due to low incidence (SpC Revision)) - Cervical smear
- Urine protein, sugar
Available screening tests for low risk women for **carrier of more common genetic condition (e.g. **thalassaemia: α: 5%, β: 3%)
- in HK no implemented guideline as to which conditions to screen
- other conditions screened in other countries: Cystic fibrosis, Spinal muscular atrophy, Fragile X syndrome, X-linked haemophilia
Expanded carrier screening (for other genetic conditions)
- screening tests using more advanced technology e.g. NGS —> check for many genetic status by same blood test
- currently not funded by public health system
- ∵ uncertain cost effectiveness, acceptance, uptake
- detailed pre-test counselling on benefits + limitations should be advised
***Antenatal screening tests in HK
First booking before pregnancy:
- 血 (4樣): Hb, MCV, Rh factor, Red cell Ab
- 病毒 (4樣): Hep B, Rubella, VDRL / FTA-ABS, HIV (opt out)
(Booking visit - 16 weeks (Felix):
- ***Early OGTT
- Indications: AMA, Obesity, Glycosuria, Family history of DM, Previous macrosomia, Previous unexplained stillbirth / abnormal babies, Polyhydramnios, Recurrent glycosuria, Previous GDM (SpC Revision)
10-12 weeks:
- **Dating scan + **AN blood (during 1st visit))
(Dating scan is less accurate when done later ∵ increased normal biological variation + occurrence of abnormal growth make estimation of gestational age inaccurate (SpC Revision))
11-(13+6) weeks:
- 1st Trimester combined Down syndrome screening (90% sensitivity) (1st tier screening)
—> **Nuchal translucency USG examination (measure skin thickness at baby’s neck fold) (only accurate during this period)
—> **Maternal serum markers (PAPP-A (Pregnancy associated plasma protein A) + hCG to estimate risk of Down’s syndrome: ***1 in 250 considered high risk)
—> if high risk / late screening —> 2nd tier
16-(19+6) weeks:
- 2nd Trimester biochemical Down syndrome screening (80% sensitivity) (1st tier screening)
—> AFP + hCG + Estriol E3 + Inhibin A
SpC Revision:
- Only Nuchal translucency: 69% accuracy
- 1st Trimester combined (i.e. NT + Maternal serum markers): 90% accuracy for singleton, 84% monochorionic twin, 70% dichorionic twin
- 2nd Trimester biochemical test: 80% accuracy
2nd tier screening:
- **Non-invasive prenatal testing (NIPT): Maternal plasma fetal DNA (higher sensitivity, but only detect trisomy 21, 18, 13 not other chromosomal abnormalities)
—> if high risk —> **Chorionic villus sampling / Amniocentesis (diagnostic)
——> **PCR: rapid aneuploidy test for Down’s
——> **Karyotyping: numerical + structural chromosomal abnormalities
——> ***Chromosomal microarray (CMA): molecular karyotyping to detect microdeletions + microduplications (preferred)
——> Genetic counselling + special arrangement if positive
18-(22+6) weeks:
- ***Structural morphology scan —> major structural problem
—> e.g. spine, head, cleft lip, heart, abdomen, kidney, limbs, amount of amniotic fluid, placental position
—> detection rate for major structural abnormalities ~80%
—> lower accuracy when: obesity, poor fetal position
28-30 weeks:
- ***OGTT for GDM
36 weeks:
- ***GBS screening
***Antenatal Thalassaemia screening
Woman’s MCV
—> MCV >=80 —> screen negative
—> MCV <80 —> screen positive —> ***Partner’s MCV
—> Partner’s MCV >=80 —> screen negative
—> Partner’s MCV <80 —> screen positive —> **Hb pattern + **Fe profile (to see whether α / β thalassaemia couple)
—> same type of thalassaemia —> prenatal diagnosis + counselling —> **DNA study, **Serial USG scan (fetal **Cardiomegaly, **placentomegaly), ***CVS / FBS
NB: Low MCV couples with normal Hb, normal A2 (β thalassaemia), no HbH granules (α thalassaemia), normal Fe studies should be managed as potential α-α couples
MCV:
- cannot pick up 1 gene deletion in α thalassaemia (asymptomatic carrier) (clinically / haematological silent (HIS06))
Diagnosis of α / β thalassaemia carrier
α thalassaemia carrier (2 gene deletion):
- HbA (α2β2)
- HbA2 (α2δ2) —> **normal
- HbF (α2γ2) —> normal
- HbH granules (β4) —> **+ve (ONLY diagnostic criteria)
- MCV **<82
- Fe: **normal / ↑
β thalassaemia carrier:
- HbA (α2β2)
- HbA2 (α2δ2) —> **↑ (diagnostic of β thalassaemia) (normal 1-3 (SC079))
- HbF (α2γ2) —> **↑ (diagnostic of β thalassaemia) (normal <1% (SC079))
- MCV <82
- Fe: normal / ↑
(presence of concomitant α thalassaemia may be masked in CBP / Hb pattern (∵ HbH inclusion bodies (β4) cannot be detected) —> need blood test for genotype to rule out concomitant α thalassaemia)
記住:
- Presence of β thalassaemia cannot be masked (∵ HbA2 / HbF一定升)
- but Presence of α thalassaemia can be masked (if no HbH inclusion bodies detected due to concomitant β thalassaemia)
—> ∴ Concomitant α + β thalassaemia —> Only see HbA2 / HbF but not HbH inclusion bodies
Management of Hb Bart’s (SpC Revision)
- Termination of pregnancy
- High risk of stillbirth and neonatal death
- Maternal complication: pre-eclampsia, postpartum hemorrhage - Repeated intrauterine transfusion
- Lifelong blood transfusion
- Stem cell transplantation
Prenatal diagnosis
Objective of ***diagnosing disorders:
- To help affected individuals by offering timely treatment
- To prevent irreversible damage
- To support if treatment if unavailable
Diagnosis by:
1. Imaging (detailed scan)
2. Fetal sampling (invasive / non-invasive)
3. Lab testing
Abnormal result
—> Pregnancy termination (then confirmation study e.g. post-mortem examination to confirm scan abnormality) / In-utero treatment (e.g. in-utero transfusion for fetal anaemia) / Delivery then treatment
Invasive tests:
1. **Chorionic villus sampling (CVS)
2. **Amniocentesis
3. ***Cordocentesis (percutaneous umbilical blood sampling of fetal blood) —> additional information on haematology of fetus e.g. anaemia
—> Chromosomal test +/- Molecular genetic test as indicated (e.g. thalassaemia)
Risks:
- Maternal (usually minimal)
- Fetal
***Comparison between CVS and Amniocentesis
CVS:
- Procedure time: **11-14 weeks
- Samples and lab test: **Cells from placenta (Chorionic villi for cytogenetic studies)
- Pain relief: ***Local analgesia
- Miscarriage risk: 0.1-0.2%
- Culture failure rate: <1%
- Normal report interpretation: normal report does not guarantee fetus free from disorders that are not chromosomal in origin
- Test accuracy: very accurate, small proportion of results may show mosaicism which may require further investigation
- Turnaround time for CMA (do not require cell culture): 7 working days
- Maternal risk: minimal
Amniocentesis:
- Procedure time: **16-20 weeks
- Samples and lab test: **Amniocytes (from amniotic fluid) for cytogenetic studies
- Pain relief: ***Not required
- Miscarriage risk: 0.1-0.2%
- Culture failure rate: <1%
- Normal report interpretation: normal report does not guarantee fetus free from disorders that are not chromosomal in origin
- Test accuracy: very accurate, small proportion of results may show mosaicism which may require further investigation
- Turnaround time for CMA (do not require cell culture): 7 working days
- Maternal risk: minimal
Risks of both (SpC Revision):
1. Miscarriage
2. Intrauterine infection
3. Amniotic fluid leakage
4. Chorioamnionitis
