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Hypertension in Pregnancy

Hypertension in Pregnancy. Tony Nicoll Consultant Obstetrician Ninewells Hospital. Outline. Objectives Physiology Classification Pre-eclampsia Pathogenesis Management Eclampsia Conclusions. Objectives.

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Hypertension in Pregnancy

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  1. Hypertension in Pregnancy Tony Nicoll Consultant Obstetrician Ninewells Hospital

  2. Outline • Objectives • Physiology • Classification • Pre-eclampsia • Pathogenesis • Management • Eclampsia • Conclusions

  3. Objectives • Understand the processes involved in antenatal care, surveillance in pregnancy, and the roles of the professionals involved (Outcomes 1-11) • Demonstrate a knowledge of the common problems encountered in obstetric practice (Outcomes 3,4,5,8)

  4. Hypertension in Pregnancy • Hypertension affects 10-15% of all pregnancies • Mild pre-eclampsia affects 10% of primigravid women • Severe pre-eclampsia affects 1% of primigravid women • Eclampsia affects 1/2000 pregnancies • Death from eclampsia = 2% • Pre-eclampsia is the commonest cause of iatrogenic prematurity • Up to 25% of antenatal admissions are due to hypertension

  5. Blood Pressure in Pregnancy • Blood pressure (BP) proportional to systemic vascular resistance and cardiac output • Pregnancy  Vasodilatation • BP falls in early pregnancy • Nadir reached at 22-24 weeks • Steady rise until Term • BP falls after delivery but subsequently rises and peaks at day 3-4 P/N

  6. Hypertension • ≥140/90 mmHg on 2 occasions • DBP >110 mmHg • ACOG - >30/15 mmHg compared to booking BP

  7. Hypertension in Pregnancy • Pre-existing hypertension • Pregnancy Induced Hypertension (PIH) • Pre-eclampsia

  8. Pre-existing Hypertension • Diagnosis prior to pregnancy • Likely if hypertension in early pregnancy (PET / PIH diseases of second half of pregnancy) • May be retrospective diagnosis if BP has not returned to normal within 3 months of delivery • Consider secondary causes - renal / cardiac, Cushing’s, Conn’s, Phaeochromocytoma • Risks include PET (X2), IUGR and abruption

  9. PIH • Second half of pregnancy • Resolves within 6/52 of delivery • No proteinuria or other features of pre-eclampsia • Better outcomes than pre-eclampsia • 15% progression to pre-eclampsia - depends on gestation • Rate of recurrence is high

  10. Pre-eclampsia

  11. Pre-eclampsia • Hypertension • Proteinuria (≥0.3g/l or ≥0.3g/24h) • Oedema • Absence does not exclude the diagnosis

  12. Pre-eclampsia • A pregnancy-specific multi-system disorder with unpredictable, variable and widespread manifestations • May be asymptomatic at time of first presentation • Diffuse vascular endothelial dysfunction widespread circulatory disturbance • Renal / Hepatic / Cardiovascular / Haematology / CNS / Placenta

  13. Pathogenesis • Genetic predisposition • Stage 1 - abnormal placental perfusion • Stage 2 - maternal syndrome

  14. Pathogenesis • Abnormal placentation and trophoblast invasion  failure of normal vascular remodelling • Spiral arteries fail to adapt to become high capacitance, low resistance vessels • Placental ischaemia  widespread endothelial damage and dysfunction • Mechanism unclear (??oxidative stress / PGI2 : TXA2 imbalance / NO) • Endothelial Activation  •  Capillary Permeability •  Expression of CAM •  Prothrombotic Factors •  Platelet aggregration • Vasoconstriction

  15. Non-Pregnant Pre-eclampsia Normal Placentation

  16. A Multi-system Disorder • CNS • Renal • Hepatic • Haematological • Pulmonary • Cardiovascular • Placental

  17. CNS Disease • Eclampsia • Hypertensive encephalopathy • Intracranial haemorrhage • Cerebral Oedema • Cortical Blindness • Cranial Nerve Palsy

  18. Renal disease •  GFR • Proteinuria •  serum uric acid (also placental ischaemia) •  creatinine / potassium / urea • Oliguria /anuria • Acute renal failure • acute tubular necrosis • renal cortical necrosis

  19. Liver Disease • Epigastric/ RUQ pain • Abnormal liver enzymes • Hepatic capsule rupture • HELLP Syndrome Haemolysis, Elevated Liver Enzymes, Low Platelets • high morbidity/ mortality

  20. Haematological Disease •  Plasma Volume • Haemo-concentration • Thrombocytopenia • Haemolysis • Disseminated Intravascular Coagulation

  21. Cardiac / Pulmonary Disease • Pulmonary oedema  ARDS • iatrogenic • disorder related • Pulmonary Embolus • High mortality

  22. Placental Disease • Intrauterine growth restriction (IUGR) • Placental Abruption • Intrauterine Death

  23. Symptoms • Headache • Visual disturbance • Epigastric / RUQ pain • Nausea / vomiting • Rapidly progressive oedema • Considerable variation in timing, progression and order of symptoms

  24. Signs • Hypertension • Proteinuria • Oedema • Abdominal tenderness • Disorientation • SGA • IUD • Hyper-reflexia / involuntary movements / clonus

  25. Investigations • Urea & Electrolytes • Serum Urate • Liver Function Tests • Full Blood Count • Coagulation Screen • CTG • Ultrasound - biometry, AFI, Doppler

  26. Management • Assess risk at booking • Hypertension < 20 weeks - look for secondary cause • Antenatal screening - BP, urine, MUAD • Treat hypertension • Maternal & fetal surveillance • Timing of Delivery • PIH can be managed as O/P in Day Care Unit

  27. Risk Factors • Maternal Age (>40 years 2X) • Maternal BMI (>30 2X) • Family History (20-25% if mother affected, up to 40% if sister) • Parity (first pregnancy 2-3X) • Multiple pregnancy (Twins 2X) • Previous PET (7X) • Molar Pregnancy / Triploidy • Multiparous women develop more severe disease

  28. Medical Risk Factors • Pre-existing renal disease • Pre-existing hypertension • Diabetes Mellitus • Connective Tissue Disease • Thrombophilias (congenital / acquired)

  29. Predicting Pre-eclampsia Normal MUAD Notch Maternal Uterine Artery Doppler 20 - 24 weeks

  30. Antenatal Screening • When to refer to AN DCU? BP  140/90 (++) proteinuria   oedema symptoms - esp persistent headache • For every 1000 “Low-risk” patients: 100 hypertensive 60 normal - 20 will return 20 DCU follow up - 10 admitted 20 admitted

  31. When to admit? • BP >170/110 OR >140/90 with (++) proteinuria • Significant symptoms - headache / visual disturbance / abdominal pain • Abnormal biochemistry • Significant proteinuria - >300mg / 24h • Need for antihypertensive therapy • Signs of fetal compromise

  32. Inpatient Assessment • Blood Pressure - 4 hourly • Urinalysis - daily • Input / output fluid balance chart • 24 hour urine collection - if proteinuria on urinalysis • Bloods - FBC, U&Es, Urate, LFTs. Minimum X2 per week

  33. Fetal Surveillance • Fetal Movements • CTG - daily • Ultrasound Biometry Amniotic Fluid Index Umbilical Artery Doppler Normal AEDF REDF

  34. Treatment of Hypertension • Treat regardless of aetiology • With MAP ≥150 mmHg there is significant risk of cerebral haemorrhage • Most treat if BP ≥150/100 mmHg • BP ≥ 170/110 mmHg requires immediate Rx • Aim for 140-150/90-100 mmHg • Control of blood pressure does not reduce the risk of developing pre-eclampsia

  35. Treatment of Hypertension (Avoid Diuretics / ACE Inhibitors)

  36. When to Deliver? • The only cure for pre-eclampsia is delivery • Mother must be stablised before delivery • Consider expectant management if pre-term • Most women delivered within 2 weeks of diagnosis

  37. Indications for Delivery • Term gestation • Inability to control BP • Rapidly deteriorating biochemistry / haematology • Eclampsia • Other Crisis • Fetal Compromise - REDF, abnormal CTG

  38. Crises in Pre-eclampsia • Eclampsia • HELLP syndrome • Pulmonary Oedema • Placental Abruption • Cerebral Haemorrhage • Cortical Blindness • DIC • Acute Renal Failure • Hepatic Rupture

  39. Steroids • Promote fetal lung surfactant production • ↓ neonatal respiratory distress syndrome (RDS) by up to 50% if administered 24-48h before delivery • Administer up to 36 weeks • Only significant effects up to 34 weeks. Proven benefit up to 1 week • Betamethasone preferred to Dexamethasone • 1 course = 12mg Betamethasone IM X2 injections 24 hours apart

  40. Eclampsia

  41. Eclampsia • Tonic-clonic (grand mal) seizure occuring with features of pre-eclampsia • >1/3 will have seizure before onset of hypertension / proteinuria • Ante-partum (38%) / Intra-partum (16%) / post-partum (44%) • More common in teenagers • Associated with ischaemia / vasospasm

  42. Management of Severe PET / Eclampsia • Control BP • Stop / Prevent Seizures • Fluid Balance • Delivery

  43. Antihypertensives • IV Labetolol • IV Hydralazine • Beware hypotension – fetoplacental unit

  44. Seizure Treatment / Prophylaxis MAGNESIUM SULPHATE Loading dose: 4g IV over 5 minutes Maintenance dose: IV infusion 1g/h If further seizures administer 2g Mg SO4 If persistent seizures consider diazepam 10mg IV

  45. Fluid Balance • Main cause of death = pulmonary oedema (Capillary leak / fluid overload / cardiac failure) • Oliguria in 30%. Does not require intervention • Any doubts about renal function  urine osmolality • Fluid challenges are potentially dangerous • Safer to run a patient “dry” - 80 ml/h

  46. Labour and Delivery • Aim for vaginal delivery if possible • Control BP • Epidural anaesthesia • Continuous electronic fetal monitoring • Avoid ergometrine • Caution with iv fluids

  47. Postpartum Management • Breast feeding • Contraception • BP management • Counselling • Future risk • Depends on other medical factors • Gestation dependent (28/40 - 40%, 32/40 - 30%) • Long term CVD risk

  48. Low Dose Aspirin • Aspirin - inhibits cyclo-oxygenase  prevents TXA2 synthesis • 75mg Aspirin 15%  reduction in PET (NNT=90) • May be more beneficial in preventing severe early onset pre-eclampsia (MRC CLASP Trial) • Safe • Used for high risk women - Renal, DM, APS, Multiple risk factors, previous PET • Commence before 12 weeks NICE Aug 2010

  49. Calcium, Antioxidants & Folic Acid • Calcium supplementation (>1gram / day) may reduce risk of hypertension (30%), PET (52%) and maternal death (20%). Did not affect pre-term birth or stillbirth (Hofmeyr et al Cochrane Database 2006) • Antioxidants not effective (Poston et al. VIP Study, Lancet 2006) • Mid trimester folic acid also appears to be effective in preventing pre-eclampsia (73% reduction) (Wen et al AJOG 2008)

  50. Conclusions • Hypertension in pregnancy is common • Pre-eclampsia is a multi-system disorder with unpredictable and variable manifestations • Pathogenesis involves abnormal placentation and widespread endothelial dysfunction • Supportive management requires maternal and fetal surveillance • No cure other than delivery • Maternal risks balanced against risks of prematurity

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