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Pre-eclampsia - Dr Deac Pimp

Definition

  • A potentially life-threatening condition of pregnancy characterised by hypertension (>140/90) and proteinuria
  • Official name is pre-eclampsia toxaemia (PET), but no evidence of actual toxaemia
  • Diagnosis from 20 weeks
  • Risk of maternal and foetal death
  • Can lead to HELLP syndrome
  • Eclampsia is characterised by seizures

 

Risk factors

  • Previous pre-eclampsia
  • PIH (pregnancy induced hypertension)
  • Family history (1st degree family)
  • First baby
  • Multiple pregnancy
  • >10 years since last pregnancy
  • Age >35
  • BMI >35 at booking
  • Pre-existing:
    • Hypertension
    • CKD (chronic kidney disease)
    • Diabetes
    • Autoimmune disorders eg SLE or antiphospholipid syndrome
  • Prevention: 75mg aspirin daily for women with any risk factors (but not first pregnancy), starting at 12 weeks

 

Differential diagnoses

  • PIH (HTN)
  • UTI (Proteinuria)
  • CKD or other kidney disease (proteinuria)
  • Phaeochromocytoma (uncontrollable HTN)

 

Epidemiology

  • Severe pre-eclampsia incidence is 5 in 1000, 0.5%
  • Eclampsia incidence is 5 in 10,000, 0.05%
  • Seizures occur postnatally in 44%, antenatally in 38% and intrapartum in 18%
  • Pre-eclampsia accounts for 20% of stillbirths
  • Maternal deaths = 9 in 2010-2012 period: 0.38 per 100,000
  • 50% deliver preterm (<36 weeks)

 

Aetiology

  • Actual cause is largely unknown
  • Thought to be related to mal-development of placental spiral arteries
    • Increased resistance
    • Starts early in pregnancy, during 2nd wave of trophoblastic development at around 12 weeks

 

Clinical features

  • Blood pressure of >140 systolic or >90 diastolic
  • AND proteinuria in absence of UTI
  • May also present with:
    • Headache, usually occipital (raised BP)
    • Excessive ankle, leg, hand, face, sacral oedema (hypoalbuminaemia/hypoproteinaemia)
    • Visual disturbances (raised ICP/cerebral oedema)
    • Small for gestational age
  • Severe pre-eclampsia:
    • RUQ (right upper quadrant)/abdo pain (subcapsular liver haemorrhage)
    • Papilloedema (raised ICP/cerebral oedema)
    • Pulmonary oedema (coarse crackles, increased RR, SOB)
    • Foetal distress
  • Eclampsia:
    • Seizure – usually standard GTCS with loss of consciousness, possibly incontinence and tongue biting
  • HELLP syndrome (Haemolysis, elevated liver enzymes, low platelets)
    • DIC
  • Stroke risk with continued malignant HTN

 

Pathophysiology

  • Stenosed and inelastic spiral arteries
    • Reduced blood flow to the foetus
    • Results in low birth weight
    • Higher chance of placental abruption in later pregnancy
  • In severe pre-eclampsia/HELLP:
    • Abnormal placental vasculature leads to platelet activation and aggregation
      • Micro-thrombi formed
        • Further obstruction of placental blood flow
        • Damage to the liver, causing raise in liver enzymes, possibly contributes to subcapsular haemorrhage
        • Uses up clotting factors, can lead to DIC and risk of haemorrhage, including subcapsular liver haemorrhage
    • Abnormal placental vasculature leads to haemolysis (of RBC)
      • May result in reticulocytosis
    • Renal involvement
      • Glomerular endotheliosis: is specific to PET, causes leaking of protein, including albumin, into urine
        • Low protein in blood leads to leaky vessels, and fluid loss into interstitial space (3rd space)
        • Peripheral oedema
        • Pulmonary oedema
        • Cerebral oedema
      • Impaired urate excretion of collecting duct, so increased serum urate

 

Investigations

  • BP (sitting or reclining, not on the side with arm above her)
  • Urinalysis (for protein, to exclude UTI)
  • Bloods
    • FBC (haemolysis, platelets <100, albumin, total protein)
    • LFTs (ALT or AST >70)
    • U&Es (urate, general kidney function)
    • Coagulation screen (DIC/reduced clotting factors)
  • Foetal monitoring:
    • CTG
    • Umbilical artery doppler
    • Foetal growth

 

Management

  • Blood pressure control:
    • Labetalol (alpha and beta blocker, not widely used outside obstetrics)
    • Methyldopa (alpha blocker)
    • Nifedipine (CCB)
  • Cerebral stabilisation:
    • Magnesium sulphate, IM or IV (also reduced BP)
    • Needs fluids/careful monitoring of fluid balance to prevent magnesium imbalance, mindful to not fluid-overload
  • Consider fluid restriction:
    • Prevent pulmonary and/or cerebral oedema
  • Consider delivery
    • C-section
    • Induction
    • If any abnormality in the bloods (thrombocytopenia, haemolysis, raised liver enzymes), consider imminent delivery
    • BP should decline after all of placenta is delivered
  • Blood tests twice weekly if mild, three times weekly if moderate/severe HTN
  • Eclampsia:
    • Resuscitation if necessary
    • Stabilise seizures:
      • Magnesium sulphate
      • Diazepam
    • Reduce BP
    • Consider foetus (monitoring, delivery)
  • Postpartum:
    • Avoid methyldopa
    • Continue BP medication, with aim to reduce as BP normalises
    • BP and urine monitoring
    • Monitor headache, oedema, RUQ pain etc
    • FBC, LFT and creatinine 72 h postpartum
    • Monitor BP every 1-2 days for first 2 weeks
    • BP and urine dip at 6 week check

 

Prognosis

  • Maternal death rate in eclampsia is 1.8%
  • PET is associated with significant poor outcomes for the infant:
    • Low birth weight
    • Preterm delivery
    • Small for gestational age
    • Infant respiratory distress syndrome
  • Increased risk of HTN and heart disease later in life
  • Increased risk of cardiovascular death during current and future pregnancies
  • 15% chance of PET recurring in subsequent pregnancies
    • 25% if PET led to delivery before 34 weeks
    • 50% if PET led to delivery before 28 weeks
    • Change of partner is protective
Pre-eclampsia.docx
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