Hypertension and Pre-eclampsia

Eclampsia

• Grand mal convulsions occurring with features of pre-eclampsia
• May occur before, during or after delivery

Physiological changes to blood pressure in pregnancy

• BP directly proportional to systemic vascular resistance and cardiac output
• Vasodilatation is primary change in pregnancy
• BP falls in early pregnancy, nadir about week 22-24
• May be low if woman supine due to diminished venous return
• falls after delivery, then rises to peak 3-4 days later
  • ?return of normal vascular tone
  • ? vasomotor instability
• Epidemiology
  •  hypertension 10-15% pregnancies
  • mild pre-eclampsia 10% primips
  • Severe pre-eclampsia 1%
  • Eclampsia 0.05%
  • Death from eclampsia 2%

Essential Hypertension

• Likely to be pre-existing problem if first appears during 1st trimester
• If require treatment before pregnancy risk of pre-eclampsia doubled
• exclude secondary causes of hypertension
  • renal disease
    • U&Es, creatinine
  • cardiac disease
  • Cushing's Syndrome
  • Conn's syndrome
  • Phaechromocytoma

Pregnancy induced hypertension

• Appears in 2nd half pregnancy and resolves in 6 weeks (may take up to 3 months)
• Without proteinuria

Pre-eclampsia

• pregnancy-specific multi-system disorder
• diffuse vascular endothelial dysfunction
• involving
  • renal
  • hepatic
  • cardiovascular
  • CNS
  • coagulation

History

• headache
• flashing lights
• epigastric / right upper quadrant pain
• nausea / vomiting
• rapidly increasing / severe swelling of face, fingers or legs

Examination

• pregnancy induced hypertension
• proteinuria
• rapidly progressive oedema
• convulsions /  mental disorientation
• intrauterine growth retardation / intrauterine death
• placental abruption

Investigations

• 24h urinary protein >0.3 g
• increased serum uric acid
• thrombocytopenia
• increased clotting time
• increased creatinine, urea
• increased haematocrit, haemoglobin
• Abnormal LFTs
• Reduced fetal growth / oligohydramnios
• abnormal / umbilical / uterine artery on Doppler

Crises

• Eclampsia
• Renal Failure
• Hepatic Rupture
• HELLP syndrome
• Cerebral haemorrhage
• DIC
• Pulmonary oedema
• Placental abruption

Causes of death

• cerebral haemorrhage
• adult respiratory distress syndrome (ARDS)

Pathogenesis

• Abnormal placentation and trophoblast invasion
• lack of vascular adaptation
• decrease in prostacyclin and increase in thromboxane A₂

Risk Factors

• Genetic factors
  • 20-25% increase in children of mothers
  • 35-40% if pre-eclampsia in sister
• Obstetric factors
  • primiparity
  • multiple pregnancy
  • hydrops with large placenta
  • hydatidiform mole
• Medical factors
  • Pre-existing hypertension
  • renal disease
  • diabetes
  • antiphospholipid antibodies

Management

• Screening for pre-eclampsia
  • serum urea, creatinine, uric acid, haemoglobin, platelet count, coagulation screen, LFTs
  • urinalysis
  • uterine artery Doppler at 20-24 weeks - good negative predictive value
• Treatment of blood pressure
  • methyldopa - causes depression so discontinue after pregnancy
  • beta-blockers
  • (calcium antagonists, hydralazine)
  • NOT ACE inhibitors - should be stopped
• Fetal surveillance
• Decision of timing of delivery
• Acute severe hypertension
  • volume expansion
  • CVP line
  • hydralazine, labetalol, nifedipine, magnesium sulphate
  • ? transfer to ITU
• Eclampsia
  • magnesium sulphate
• Delivery
  • encourage to have epidural
  • avoid ergometrine
• Prophylaxis
  • low dose aspirin

[ Home ] [ Up ]