Hypertensive Disease in Pregnancy

Question 1

Chronic vs Gestational Hypertension

Answer 1

• Chronic if HTN before 20 weeksin absence of hydatiform mole or persistent HTN beyond 6 weeks postpartum
• Gestational can be divided into:
  
  • HTN without proteinuria
  • Proteinuria without HTN
  • Proteinuric HTN (pre-eclapmsia)

Question 2

Definition of pre-eclampsia

Answer 2

• HTN develping after 20 weeks gestation with one or more of proteinuria, maternal organ dysfunction or fetal growth restriction
• Potential forms of organ dysfunction include
  
  • Renal insufficiency (creatinine >90micromol/L)
  • Liver involvement (elevated transaminases + abdominal pain)
  • Neurological complications (eclampsia, altered mental status, blindness, stroke, hyperreflexia, headache)
  • Haematological complications (thrombocytopenia, DIC, haemolysis)

Question 3

Definition of severe pre-eclampsia

Answer 3

• Pre-eclampsia with severe hypertnsion +/- symptoms +/- biochemical or haematological impairment

Question 4

Definition of clampsia

Answer 4

• Generalised tonic-clonic convulsions in women with pre-eclampsia if seizures cannot be attributed to other causes

Question 5

Pathophysiology

Answer 5

• Phase 1 - Abnormal Placentation
  
  • Normal - trophoblast invasion of maternal spiral arteries cause the diameter to increase 5 fold, converting high resistance, low low to low resistance, high flow.
  • Abnormal (pre-eclampsia) - inadequate trophoblast invasion, causing inadequate placental perfusion caused by maternal immune reaction of paternal antigens expressed by fetus
• Phase 2 - Endothelial Dysfunction
  
  • Widespread endothelial damage and dysfunction
  • Likely to be mediated by oxidative stress originating from the ischaemic placenta
  • Endothelial damage promotes platelet adhesion and thrombosis, and disturbs normal vascular tone
  • Exaggerated maternal systemic inflammatory response, with activation of leucocytes, platelets and the coagulation system
  • Relative deficiency of prostacyclin (vasodilator) and increased thromboxane A2

Question 6

Risk factors

Answer 6

• First pregnancy
• Family history
• Extremes of maternal age
• Obesity
• Medical factors
  
  • Pre-existing HTN
  • Renal disease
  • Diabetes
  • Acquired or inherited thrombophilia
  • CTD
• Obstetric factors
  
  • Multiple pregnancy
  • Previous pre-eclampsia
  • Hydrops fetalis (immune and non-immune)
  • Hydatiform mole
  • Triploidy
  • Inter-pregnancy interval >10 years

Question 7

Presentation

Answer 7

• Severe headache
• Severe RUQ/epigastric pain
• Sudden swelling of hands, face or feet
• Visual disturbance including blurring, flashing, scotoma
• Vomiting
• Restlessness or agitation
• HTN and proteinuria
• Hyperreflexia
• Serum creatinine raised
• Platelet count decreased
• Clonus
• Haemolytic anaemia
• Elevated liver enzymes
• Retinal haemorrhages and papilloedema

Question 8

Clinical assessment

Answer 8

• Full assessment to differentiate HTN disorders
• BP
• Urinalysis for proteinuria
• Blood tests (AST and transaminitis indicate hepatocellular damage)
• Consider HEELP (haemolysis, elevated liver enzymes and low platelets)

Question 9

Blood tests

Answer 9

• FBC
  
  • Low platelets
  • Low Hb
  • Haemolysis on blood film
• Renal function
  
  • Reduced urine output
  • Increased urate
  • Increased urea
  • Increased creatinine
• Coagulation system
  
  • Prolonged coagulations indices
• Hepatic system
  
  • Elevated ALT
  • Elevated AST

Question 10

Fetal assessment

Answer 10

• Symphysial fundal height
• US for fetal growth, liquor volume and umbilical artery doppler
• If there is fetal compromise - delivery

Question 11

Prevention

Answer 11

• Aspirin inhibits prostaglandin synthesis via COX
• Low dose aspirin should inhibit the vascular and prothrombotic effects of thromboxane A2 in women at risk of pre-eclampsia

Question 12

Management

Answer 12

• Control maternal BP
• Assess fluid balance (too much = renal pulmonary oedema, too little = renal failure)
• Prevent seizures (eclampsia) - use magnesium sulphate
• Consider delivery
  
  • Maternal indications - gestation >37 weeks, failure to control HTN, deteriorating liver/renal function, progressive fall in platelets, neurological complications
  • Fetal indications - abnormal fetal HR, deteriorating fetal condition
• Optimise postnatal care

Question 13

Drug treatment

Answer 13

• Methyldopa
  
  • Central action
  • Intial drowsiness
  • Safe, slow onset, not suitable if Hx of depression
• Labetalol
  
  • Alpha and beta antagonist
  • Postural hypotension, tiredness
• Hydralazine
  
  • Direct-acting vasodilator
  • Hypotension
• Nifedipine
  
  • Calcium-channel antagonist
  • Flushing, headaches
  • Watch for precipitous fall in BP when used with magnesium sulphate

Question 14

Complications

Answer 14

• Maternal
  
  • Intracranial haremorrhage
  • Placental abruption and DIC
  • Eclampsia
  • HELLP synfrome (haemolysis, elevated liver enzymes and low platelets)
  • Renal failure
  • Pulmonary oedema
  • Acute respiratory arrest
• Fetal
  
  • IUGR
  • Oligohydramnios
  • Hypoxia from placental insufficiency
  • Placental abruption
  • Premature delivery