Hypertension in Pregnancy Flashcards
Definitions of Hypertension
> /= 140/90 mmHg on 2 occasions
> 160/110 mmHg once
(ACOG - >30/15 mmHg compared to first trimester BP)
Types of hypertension in pregnancy
Pre-existing
PIH
Pre-eclampsia
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)
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
Secondary causes of pre-existing hypertension
Renal/cardiac
Cushing’s
Conn’s
Phaeochromocytoma
What are the risks of pre-existing HTN
PET (x2)
IUGR
Abruption
When is PIH diagnosed?
2nd half of pregnancy
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
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
Aetiology of pre eclampsia and the systems it may affect
Diffuse vascular endothelial dysfunction widespread circulatory disturbance
Renal / Hepatic / Cardiovascular / Haematology / CNS / Placenta
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
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
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
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
How to identify HELLP syndrome in pre-eclampsia?
LFT and liver enzymes
Placental disease in pre-eclampsia
Fetal growth restriction (FGR)
Placental abruption
Intrauterine death
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
