HTN in pregnancy/ Preeclampsia Flashcards
Types of HTN in pregnancy
- Pre-existing or chronic HTN
- Pre-pregnancy OR First recognized in 1st trimester of pregnancy - Pregnancy-induced HTN
- Presents after 20 weeks’ gestation in previously normotensive woman
- NO PROTEINURIA pregnancy-induced HTN - Superimposed pre-eclampsia
- Presents after 20 weeks’ gestation
- Exacerbation of pre-existing HTN / gestational HTN with evidence of multisystem disorder
Definition of pre-eclampsia
A multisystem progressive disorder of pregnancy characterised by
- HTN and proteinuria
- HTN and at least one end organ involvement (sx can manifest at different times)
Onset of pre-eclampsia occurs
after 20 weeks gestation
Diagnostic criteria of pregnancy-induced hypertension
BP:
- ≥140/90 on 2 occasions 4h apart OR
- ≥ 160/110 on one occasion
NO Proteinuria in PIH but for pre-eclampsia:
- ≥0.3g/24h OR
- Spot urine protein:creatinine ratio ≥30 mg/mmol OR
- Dipstick proteinuria ++ or more (in the absence of UTI)
*cut-off is only applicable to women NOT on anti-hypertensives
*if mother is already on anti-hypertensives, look at trend instead
Definition of eclampsia
Grand mal seizure activity and/or unexplained coma in a woman with signs or symptoms of pre-eclampsia, due to cerebral vasoconstriction
Risk factors of pre-eclampsia
REVIEW risk factors at booking visit
HIGH RISK:
- Previous pre-eclampsia or gestational hypertension
- Pre-existing hypertension
- Pre-existing kidney disease
- Diabetes Mellitus
- Anti-phospholipid syndrome
- SLE
MODERATE RISK:
- Maternal age 40yo and more, teenager
- First pregnancy
- New partner
- Pregnancy interval of more than 10 years
- BMI of 35kg/m2 or more
- FHx of pre-eclampsia in mother/ sister
- Multi-fetal pregnancy
- IVF
Protective RF of pre-eclampsia
Smoking
What are the indications to qualify for prophylaxis?
Only ONE high risk factor is needed to qualify for prophylaxis OR 2 moderate risk factors
Pathophysiology of pre-eclampsia
Spiral artery remodelling that occurs between 12-30 weeks of gestation
In pre-eclampsia, there is incomplete transformation of spiral artery and after 20 weeks there will be no more transformation, signs and symptoms will start to manifest and cannot be undone
Shallow extravascular trophoblast invasion into maternal tissues + Incomplete transformation of spiral artery
-> placental hypoxia
Organs affected in pre-eclampsia and accompanying symptoms
Brain
- Headache
- Visual disturbances (BOV/ flashing of lights)
- Clonus and brisk deep tendon reflexes
Lungs
- Pulmonary edema
- Pulmonary embolism
Heart
- CHF
Liver
- N/V
- Epigastric pain
Kidney
- Oliguria
- Proteinuria
Fetus
- IUGR
Malplacentation
- Reduced fetal movements
- Placenta abruptio: abdo pain, vaginal bleeding
Blood
- Thrombocytopenia
- DIVC
Oedema
- Swelling (extremities/ face/ sacral)
- DVT
Severe forms of HTN disorders
- HELLP syndrome
- Haemolysis
- Elevated Liver enzymes
- Low Platelets
*can occur in the absence of HTN and proteinuria
- Eclampsia
Prophylaxis for pre-eclampsia
If patient has ONE high risk factor OR 2 moderate risk factors, START:
- Low dose aspirin (100-150mg every night) (150mg nowadays)
- Start between 12-16 weeks of gestation, stop at 36 weeks - Calcium supplementation (1.5-2g daily) if low dietary calcium
Early detection and monitoring: MATERNAL
- Regular antenatal checks
- BP
- Dipstick proteinuria - Symptom review
- Low threshold to perform further ix if suspicious
- Bloods: FBC, LFT, RP
- Quantify proteinuria: 24h proteinuria >0.3g/24h (conventional) or spot urine protein creatinine ratio >30 mg/mmol
Early detection and monitoring: FETAL
- Fetal movements
- Serial symphysio-fundal heights
- Fetal heart auscultation
- Ultrasound scanning
What is assessed for during the ultrasound screening of fetus?
Findings in Malplacentation
Late 2nd trimester:
- Maternal uterine artery doppler: uterine artery doppler notching (uteroplacental perfusion screening test)
In 3rd trimester:
- Fetal growth (biometry – Head Circumference, Abdominal Circumference, Femur Length, calculate estimated fetal weight)
- Umbilical artery dopplers (fetal perfusion of placenta)
- Middle cerebral artery dopplers (proxy of fetal oxygenation)
- Amniotic fluid (Oligohydramnios may indicate placental insufficiency)
Symptoms of impending eclampsia
- Severely elevated BP > 160/110mmHg & gross proteinuria > 3+ or > 3g/24h
- Biochemical abnormalities or thrombocytopenia
Symptoms
Severe headache
Sudden swelling of face/ hands/ feet
Pulmonary edema
Blurring/ flashing lights
RUQ pain
Nausea/ vomiting
Clonus ≥3 beats and brisk deep tendon reflexes (Imminent seizure)
Papilledema
Follow eclampsia management
Management of pre-eclampsia: Maternal
- Anti-hypertensives and BP monitoring: target 135/85
a. Labetolol (oral in mild-mod, IV in severe) - if no asthma
b. Oral nifedipine
c. IV hydralazine (if refractory/ fulminant pre-eclampsia)
d. Oral methyldopa (slow onset, not suitable for acute situation) - IV magnesium sulphate if severe (≥160/>110mmHg) pre-eclampsia
- Reduce risk of eclampsia
- If very preterm <32w – neuroprotective effects on fetus - Fluid restriction
- Monitor urine output, fluid balance chart, consider CVP monitoring - Venous Thromboembolism prophylaxis
- TEDS, clexane (usually postnatal) - End organ management
Management of pre-eclampsia: Fetal
- Antenatal steroids (IM dexamethasone) if preterm:
- Promote fetal lung maturity
2a. Cardiotocography (CTG) monitoring for signs of fetal hypoxia in acute situation
2b. Ultrasound monitoring for growth and fetal wellbeing in expectant situation
Delivery in pre-eclampsia mommies
Balance risk of prematurity from early iatrogenic delivery vs maternal/fetal
morbidity/mortality from pre-eclampsia
- Vaginal vs C-sect
- Aim to deliver at least after 34 weeks (if really necessary) as women are less responsive to IOL drugs before 34w
- Aim 37-38 weeks
- If preterm, whenever uterine contracts (every few mins), the spiral artery gets squeezed and cuts off blood supply to fetus hence C-sect is preferred for delivery as VD increases risk of fetal distress
Post-natal management
Immediate post-partum - HDU care
- PPH prophylaxis
- Fluid management (continue restriction, diuresis with recovery)
- VTE prophylaxis (TEDS, clexane)
- Still at risk of eclampsia/HELLP, especially in first 48h.
- Repeat FBC, liver, renal profiles at 48-72h if antenatally normal. More frequently if abnormal.
- Encourage breast-feeding
After discharge from hospital
- Gradual reduction of anti-hypertensives
- Normalization of BP/proteinuria by 6 weeks, if not investigate for medical disorders
- Avoid combined oral contraceptive pills containing oestrogen
- Avoid inter-pregnancy interval >10y
Counsel:
- Recurrence risk in future pregnancies: higher with pre-eclampsia < 32 weeks or if existing medical condition
- Long term risk of stroke, hypertension, heart disease –> lifestyle changes: wt loss, exercise, low salt
Mode of delivery in eclampsia
DELIVER STAT
Magnesium sulphate toxicity
Therapeutic range: 2-4 mmol/L
>5: Loss of reflexes (patella)
6-7.5: Paralysis, respiratory arrest (Check SpO2)
>12: Cardiac arrest (Check ECG)
- Insert IDC for I/O charting
- Stop MgSO4, check serum Mg, if >4 then give antidote: Calcium gluconate (10ml 10% as slow bolus)
- Also check UECr (trend it) TRO AKI
Antidote for magnesium sulphate toxicity
if >4 then give: Calcium gluconate
Management of chronic HTN in pregnant mom
- Stop ACEI/ ARB/ Thiazide diuretics (Congenital abnormalities)
- Target BP 135/85 mmHg
- Options
PO Methyldopa
PO Labetalol
PO Nifedipine
PO Aspirin 75-150mg OD - Monitoring (same as above)
- Delivery: Normal
If patient has pregnancy-induced HTN, indications to admit hospital includes:
- BP >160/110mmHg
- P/w S/S of pre-eclampsia
C/I of MgSO4
Mysthenia gravis
Why do we not use methyldopa nowadays?
Risk of depression
Risk of PE in the next pregnancy?
If prev pregnancy developed severe PE before 32 weeks -> risk of next pregnancy is 40% to have PE
If prev pregnancy developed mild PE -> risk of next pregnancy is 25% to have PE
