Hypertension in Pregnancy Flashcards by Arya Nedungadi

Definitions of Hypertension

> /= 140/90 mmHg on 2 occasions

> 160/110 mmHg once

(ACOG - >30/15 mmHg compared to first trimester BP)

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Types of hypertension in pregnancy

Pre-existing
PIH
Pre-eclampsia

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Effect of maternal CVS adaptations on BP

Mid trimester dip in BP (slight, not so significant)

Rise in HR (also slight and not too significant)

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When is Pre-exisiting HTN diagnosed during pregnancy

Diagnosed prior to pregnancy

May be retrospective diagnosis if BP has not returned to normal within 3 months of delivery

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Secondary causes of pre-existing hypertension

Renal/cardiac
Cushing’s
Conn’s
Phaeochromocytoma

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What are the risks of pre-existing HTN

PET (x2)
IUGR
Abruption

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When is PIH diagnosed?

2nd half of pregnancy

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Features of PIH

Resolves within 6/52 of delivery
No proteinuria or other features of pre-eclampsia
Better outcomes than pre-eclampsia
Rate of recurrence is high

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What are the features of pre-ecclampsia

3 features (all 3 need not be present to have pre-ecclampsia):

Hypertension

Proteinuria (≥0.3g/l or ≥0.3g/24h)

Oedema

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Aetiology of pre eclampsia and the systems it may affect

Diffuse vascular endothelial dysfunction widespread circulatory disturbance

Renal / Hepatic / Cardiovascular / Haematology / CNS / Placenta

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2 classifications of pre-eclampsia

Early: <34 wks

uncommon
Higher risk of maternal and foetal complications
Associated with extensive villous and vascular lesions of the placenta

Late

Common
minimal placental lesions
Higher maternal mortality

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Pathogenesis of pre-eclampsia

Environmental/ genetic predisposition

Stage 1: Abnormal placental perfusion ( leads to placental ischemia and infarction)

Stage 2: Maternal syndrome as a result of stage 1.
- endothelial changes/dysfunction

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Normal placentation vs Pre-eclamptic placentation

Normal:

cytotrophoblasts invade muscle layer of spiral arteries
this causes spiral arteries to open up and allows adequate blood flow to foetus

Pre-eclampsia:

no cytotrophoblast invasion of muscle of spiral arteries
growth restriction
hypoxia/ischemia

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Presentation of HELLP SYNDROME (subtype of severe pre-eclapmsia)

Epigastric/ RUQ pain
Abnormal liver enzymes
Hepatic capsule rupture

Haemolysis, Elevated Liver Enzymes, Low Platelets
- high morbidity/ mortality

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How to identify HELLP syndrome in pre-eclampsia?

LFT and liver enzymes

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Placental disease in pre-eclampsia

Fetal growth restriction (FGR)

Placental abruption

Intrauterine death

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How does pre-eclampsia present?

Depends on the system affected (some might be asymptomatic)

CNS symptoms:
Headache
Visual disturbance

Liver: Epigastric / RUQ pain

GI: Nausea / vomiting

Rapidly progressive oedema - “do your rings get stuck on your finger?”

What are the findings on examination (signs)?

Hypertension
Proteinuria
Oedema
Abdominal tenderness
Disorientation
Small for Gestational Age (SGA) Fetus
Intra uterine fetal death
Hyper-reflexia / involuntary movements (eclamptic seizure) / clonus

Investigations for pre-eclampsia

Urea & Electrolytes

Serum Urate – first change seen (specific in preg)

Liver Function Tests (HELLP)

Full Blood Count (haemolysis, thrombocytopaenia)

Coagulation Screen (liver disease, maternal clotting problems)

Urine - Protein Creatinine Ratio (PCR)

Cardiotocography (to asses baby)

Ultrasound - fetal assessment

Management of Pre-eclampsia

Assess risk at booking - identify risk factors

Hypertension < 20 weeks - look for secondary cause

Antenatal screening - BP, urine, MUAD (to asses placent)

Treat hypertension

Maternal & fetal surveillance

Timing of Delivery -pre-eclampsia and HTN problems do not resolve till baby is delivered

Risk factors for pre-eclampsia

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 PE (7X)
Birth interval >10 years (2X)
Molar Pregnancy / Triploidy
Multiparous women develop more severe disease

Medical risk factors for pre-eclampsia

Pre-existing renal disease
Pre-existing hypertension
Diabetes (pre-existing/gestational)
Connective tissue disease
Thrombophilias (congenital / acquired- more common)

When is low dose aspirin given to manage pre-eclampsia

In case risk factors are identified

MOA of low dose aspirin in pre-eclampsia management

Inhibits cyclo-oxygenase thus prevents TXA2 synthesis

15% reduction in PET (NNT=90)

May be more beneficial in preventing severe early onset pre-eclampsia (MRC CLASP Trial)

Commence before 16 weeks

Nice guidelines for low dose aspirin in pre-eclampsia

5mg (NICE recommendation) | 100mg - better

What is the transformation of MUA during pre-eclampsia?

turn from high capacity low resistance to the converse

When can pre-eclampsia be predicted using MUAD?

20-24 weeks | Appears as notch waveform indicating high resistance artery and placentation hasn't occurred as expected

When to refer to AN Day Care Unit?

BP >/= 140/90 (++) proteinuria ++ oedema symptoms - esp persistent headache

When to admit pregnant mother for pre-eclampsia?

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

What is the inpatient assessment for pre-eclampsia?

Blood Pressure - 4 hourly Urinalysis - daily Input / output fluid balance chart (to monitor kidney func) Urine PCR - if proteinuria on urinalysis Bloods - FBC, U&Es, Urate, LFTs. Minimum X2 per week but daily for inpatient

When to stat treatment of HTN in pregnancy

Most treat if BP ≥150/100 mmHg BP ≥ 170/110 mmHg requires immediate Rx Aim for 140-150/90-100 mmHg - do not drop the BP to low as an increased BP is a maternal adaptation to pregnancy Control of blood pressure does not reduce the risk of developing pre-eclampsia

Drugs used to treat HTN in pregnancy (1st line)

Methyldopa - - Centrally acting a agonist - Starting dose 250mg bd - 1 gram tds - CI: Depression Nifedipine Ca channel antagonist Starting dose: 10mg bd Max dose: 40mg bd ``` Labetalol a + b antagonist start dose: 100mg bd Max dose: 600mg qid CI: Asthma ```

2nd line drugs used to treat HTN in pregnancy

Hydralazine - Vasodilator - 25mg tds - 7mg qid (max dose) Doxazocin - a antagonist - 1 mg OD - 8mg BD (max dose)

HTN drugs to avoid during pregnancy

Diuretics | ACE inhibitors

Techniques used in foetal surveillance

CTG - daily Ultrasound - - Biometry - Amniotic Fluid Index - Umbilical Artery Doppler

Indications for birth

``` Eclampsia HELLP syndrome Pulmonary Oedema Placental Abruption Cerebral Haemorrhage Cortical Blindness DIC Acute Renal Failure Hepatic Rupture ```

What is eclampsia?

Tonic-clonic (grand mal) seizure occurring with features of pre-eclampsia More common in teenagers Associated with ischaemia / vasospasm

Management of severe PET/Eclampsia

Control BP Stop / Prevent Seizures Fluid Balance Delivery

Seizure treatment/prophylaxis in eclampsia

MAGNESIUM SULPHATE Loading dose: 4g IV over 5 mins Maintenance dose: IV 1g/h further seizure - 2mg Persistent seizures: Diazepam 10mg IV

Fluid balance and eclampsia

Main cause of maternal 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

Labour and birth

``` Aim for vaginal birth if possible Control BP Epidural anaesthesia Continuous electronic fetal monitoring Avoid ergometrine Caution with iv fluids ```

Post-partum management

``` Breast feeding Contraception BP management Counselling / debrief Future risk Depends on other medical factors Gestation dependent (28/40 - 40%, 32/40 - 30%) Consider long term cardiovascular risk ```