Hypertension in pregnancy

1. PIH (pregnancy induced hypertension / gestational hypertension)

2. Pre-eclampsia / PET (pre-eclampsic toxemia)

3. Eclampsia

4. Chronic hypertension

5. Chronic hypertension superimposed pre-eclampsia

Definition:

PIH

1. Hypertension (SBP>140 or +30 , DBP>90 or +15)

2. Arising 1^st time in 2^nd half of pregnancy

3. Absence of proteinuria

4. Not associated with adverse pregnancy outcome

Pre-eclampsia / PET

1. Hypertension >140/90mmHg ( measured in 2 separate occasion – at least 4hrs )

2. Presence of protein >300mg/24hrs urine sample

3. Occur after 20wk POG

4. Resolving completely 6^th postpartum wk

· PIH pt with HT>170/100 taken as PET

Eclampsia

1. Convulsion occur in woman with established pre-eclampsia

2. Absence of any other neurological and metabolic cause

3. Is a obstetric emergency (serious & life threatening)

Chronic hypertension

1. With/without renal disease

2. Existing prior to pregnancy

3. Is a different aetiology from pre-eclampsia

Chronic hypertension superimposed pre-eclampsia

1. Chronic hypertension can predisposed to this

Pre-eclampsia

Symptoms-

· May be asymptomatic

· Frontal headache (not responding to PCM)

· Visual disturbances

· Epigastric/right upper abdominal pain

· Heart failure symptoms

Signs-

· ↑ BP

· Fluid retention (non-dependent oedema)

· Brisk reflexes

· Ankle clonus (>3 beats)

· SFH <>

Incidence-

· 3% of pregnancy

· 15% maternal death (2^nd commonest cause of death in late pregnancy and puerperium)

Epidemiology-

· Primigravid women ↑ risk

· Prolong exposure to paternal antigen (prolong unprotected sex) ↓ risk

· Women has a child (from previous marriage) with new husband ↑ risk

· 1^st degree relatives ↑ risk

Risk factors-

· Placenta enlarged conditions (multiple pregnancy, DM, hydrops)

· Pre-existing HT, renal disease

· Pre-existing vascular disease (DM, autoimmune vasculitis)

Aetiology-

· Trophoblast tissue stimulation

Pathophysiology-

· In normal pregnancy; peripheral vasodilatation → less sensitivity to vasoconstrictors (eg: angiotensin)

· In pre-eclampsia; activation/dysfunction of vascular endothelial cells → insensitivity to vasoconstrictor lost & ↓ sensitivity to vasodilators → vasospasm → platelet activation, micro-aggregation formation

· Loss of endothelial integrity → oedema

· CVS-

§ Generalized vasospasm

§ ↑ peripheral resistance

§ ↓ central venous/pulmonary wedge pressure

· Haematological-

§ Platelet activation and depletion

§ Coagulopathy

§ ↓ plasma volume

§ ↑ blood viscosity

· Kidneys-

o Glomeruloendotheliosis (characteristic lesion) – endothelial & mesengial cell swelling, little disruption of podocytes → Proteinuria , ↓ clearance of uric acid & oliguria (specific to pre-eclampsia, not seen in HT due to other causes)

§ Proteinuria

§ ↓ GFR

§ ↓ Urate excretion

· Liver-

o Subendothelial fibrin deposition → ↑ Liver enzymes → Haemolysis, Low Platelet count

HELLP syndrome – Haemolysis, Elevated Liver enzymes, Low Platelet

Occur in severe pre-eclampsia

§ Periportal necrosis

§ Subcapsular haematoma

· Brain-

§ Cerebral oedema

§ Cerebral haematoma

§ Progression to eclampsia

o Retinal haemorrhage, exudates, papilloedema – in hypertensive encephalopathy is rare in pre-eclampsia

· Placenta-

§ Acute atherosis of the spiral arteries

§ Platelet microaggregates

§ Large thrombosis

Screening tests-

· Doppler USS – uterine artery, Incomplete trophoblast invasion of the spiral artery

Preventive therapy-

· Aspirin low dose (75mg) daily

Management & Treatment-

· Principles

o Early recognition

o Awareness of severity

o Hospital admission, investigation, antihypertensive, anticonvulsants

o Well-timed delivery, fetal complications

o Postnatal follow-up, counseling

· Investigations

o Urinalysis (ward test/dipstick)

o 24 hrs urine collection (total protein & cratinine)

o FBC (platelets & haematocrit)

o Blood chemistry (renal function, protein concentration)

o Plasma uric acid (urate)

o Liver function

o Coagulation profile

o USS – fetal size/amniotic fluid volume/maternal & fetal/doppler

· Antihypertensive therapy

o Labetotol

Alpha & beta blocker

Oral & IV

Safe in pregnancy

o Methyldopa

Centrally acting

Safe in pregnancy

Only orally

Take 24 hrs to give effects (not suitable for emergency)

o Nifedipine

Ca channel blocker

Rapid action

ADE – severe headache

o Hydralazine

Use in severe cases

IV infusion

Rapid ↓ of BP

· Treatment – Eclampsia

o Magnesium sulphate – drug of choice

IV

↓ further convulsions

Complications – pre-eclampsia

· Multiple organ failure

· DIC (Disseminated Intravascular Coagulation)

· ARDS (Adult Respiratory Distress Syndrome)

· Renal failure

Management of delivery – pre-eclampsia

· Optimized fetal conditions prior to delivery

· Dexamethasone (12mg IM bd 12hrly) to reduce neonatal pulmonary insufficiency

· If need – transmit to 3ry care

· Delivery

o Before term – LSCS

High risk for thromboembolism

· Prophylactic SC Heparin

· Antithromboembolic stockings

o Term/spontaneous - NVD

Epidural

Avoid Ergometrine