Hypertension in Pregnancy Flashcards
What percentage of pregnancies does hypertension usually affect?
10-15% of all pregnancies
How many primigravid (1st baby) mothers experience pre-eclampsia?
Mild pre-eclampsia = 10% primigravid women
Severe pre-eclampsia = 1% primigravid women
What is eclampsia?
seizure as a result of severe pre-eclampsia
- high risk of maternal death
When in pregnancy do changes in the cardiovascular system usually occur?
First 12 weeks
What cardiovascular changes does a mother experience in pregnancy?
- Increased plasma vol and CO
- Peripheral vascular resistance decreases
What trends in BP and heart rate are thought to occur in 2nd/3rd trimester of pregnancy?
- 2nd trimester = dip in BP (less marked than previously thought)
- 3rd trimester = increase in HR (around 7bpm)
What is the quantitative definition of hypertension?
≥140/90 mmHg on 2 occasions
>160/110 mmHg once
(some areas of world use increase of >30/15mmHg since 1st trimester)
What different types of hypertension can result during pregnancy?
- Pre-existing hypertension
- Pregnancy Induced Hypertension (PIH)
- Pre-eclampsia
What is the difference between Pregnancy Induced Hypertension (PIH) and Pre-eclampsia?
NO proteinuria or oedema in PIH
When is pre-existing hypertension most often diagnosed?
- 1st trimester => Likely if early pregnancy
- Retrospective diagnosis after pregnancy (if BP not returned to normal within 3 months of delivery)
What secondary causes may be responsible for pre-existing hypertension?
Renal / cardiac/ Endocrine
- Cushing’s
- Conn’s
- Phaeochromocytoma
What does pre-existing hypertension increase the risk of in pregnancy?
- PET
- IUGR
- Placental abruption
When does PIH normally present and resolve?
Second half of pregnancy
Resolves within 6/52 of delivery
What risks does pregnancy induced hypertension present?
- Progression to pre-eclampsia (15%)
- Rate of recurrence is high
What are the main features of pre-eclampsia?
Hypertension
Proteinuria (≥0.3g/l or ≥0.3g/24h)
Oedema
Pre-eclampsia can be “asymptomatic” on presentation. TRUE/FALSE?
TRUE
- patient may experience high BP, proteinuria and oedema but not feel unwell/ any abnormal symptoms
Describe the difference between early and late presentations of pre-eclampsia
Early
- extensive villous and vascular lesions of placenta
- higher risk of complications than late pre-eclampsia
Late
- minimal placental lesions
- relatively benign disease course but can lead to eclampsia
Describe the pathogenesis of pre-eclampsia
- Genetic (eg increased risk if mother/sister affected)
- environmental predisposition
- Stage 1 - abnormal placental perfusion
=> placental ischaemia/ infarction - Stage 2 - maternal syndrome
=> trophoblast invasion
=> failure of normal vascular remodelling
=> Spiral arteries fail to adapt to become high capacitance, low resistance vessels
=> Placental ischaemia
How does pre-eclampsia affect the liver to cause disease?
- Epigastric/ RUQ pain
- Abnormal liver enzymes
- Hepatic capsule rupture
- HELLP Syndrome
=> Haemolysis, Elevated Liver Enzymes, Low Platelets
What complications can pre-eclampsia cause which are specific to the placenta?
Fetal growth restriction (FGR)
Placental abruption
Intrauterine death
What symptoms normally present with pre-eclampsia?
- Headache
- Visual disturbance
- Epigastric / RUQ pain
- Nausea / vomiting
- Rapidly progressive oedema
Aside from the 3 common diagnostic signs, what other signs may be observed on examination of a mother with suspected pre-eclampsia?
- Abdominal tenderness
- Disorientation
- Small for Gestational Age (SGA) Fetus
- Intra uterine fetal death
- Hyper-reflexia / involuntary movements / clonus
(these signs develop prior to eclampsia seizure)
What investigations should be carried out throughout pregnancy if a mother has pre-eclampsia?
- Serum Urate
- LFTs
- FBC
- Coagulation Screen
- Cardiotocography
- US
What maternal risk factors can increase the likelihood or severity of pre-eclampsia?
Maternal Age BMI Family Hx Parity (first pregnancy) Multiple pregnancy (Twins/Triplets etc) Previous Pre-eclampsia Birth interval >10 years Molar Pregnancy / Triploidy
Women who develop pre-eclampsia in subsequent pregnancies experience greater severity that women in their first pregnancy. TRUE/FALSE?
TRUE
What conditions in a mother’s PMHx may increase the risk of pre-eclampsia in pregnancy?
Pre-existing renal disease Pre-existing hypertension Diabetes (pre-existing/gestational) Connective tissue disease Thrombophilias (congenital / acquired)
When should low dose aspirin be started in pre-eclampsia?
- Commence before 16 weeks
- Usually taken from 12 weeks until birth
(150 mg dose Tayside, but NICE = 75mg)
How may pre-eclampsia be predicted from a maternal uterine artery doppler?
High resistance and low flow found in preeclampsia appears as low flow/ minimal colour on doppler US
When should a mother with pre-eclampsia be admitted to hospital?
- BP >170/110 OR >140/90 with (++) proteinuria
- Significant symptoms - headache / visual disturbance / abdominal pain
- Abnormal biochemistry
- Significant proteinuria - >300mg / 24h
- Need antihypertensive therapy
- Signs of foetal compromise
How should mothers suffering from pre-eclampsia be assessed when they are inpatients?
BP - 4 hourly Urinalysis - daily Input / output fluid balance chart Urine PCR - (if proteinuria present) Bloods - FBC, U+Es, Urate, LFTs usually daily (min 2/wk)
When are most women treated for hypertension?
BP ≥150/100 mmHg
BP ≥ 170/110 mmHg = immediate Tx!
Control of blood pressure does not reduce risk of developing pre-eclampsia NOR DOES IT CURE PRE-ECLAMPSIA (only cure = delivery of baby)
What agents can be used to treat hypertension in pregnancy and when are these contrainidcated?
Methyldopa (contraindicated in depression)
Labetalol (contraindicated in asthma)
Nifedipine SR
2nd line:
Hydralazine
Doxazosin (not suitable in breastfeeding)
What does a decreasing or LOW Amniotic Fluid Index
indicate?
Baby is not producing enough urine/amniotic fluid
=> in distress/ill
=> Kidneys are not functioning well
What can be assessed on an Umbilical Artery Doppler?
Blood flow to baby during diastole
- can be normal, absent or reversal of blood flow
What indications in pre-eclampsia would suggest to deliver the baby?
- Term gestation
- Inability to control BP
- Rapidly deteriorating biochemistry / haematology
- Eclampsia
- Foetal Compromise - abnormal US or CTG
What crises can occur in pre-eclampsia that usually indicate to get the baby out?
Eclampsia HELLP syndrome or Hepatic Rupture Pulmonary Oedema Placental Abruption Cerebral Haemorrhage Cortical Blindness Acute Renal Failure
When do most eclampsia seizures occur?
24 hours post partum
How is severe pre-eclampsia or eclampsia itself managed?
Control BP - IV Labetolol or Hydralazine (beware hypotension)
Stop / Prevent Seizures - Mg sulphate IV (diazepam if this doesn’t work)
Fluid Balance - slow infusion rate to “run patient dry” => 80 ml/h
Delivery
What should you aim for in labour when a mother has pre-eclampsia?
- vaginal birth if possible
- Control BP
- Epidural anaesthesia
- Continuous foetal monitoring
- Avoid ergometrine
- Caution with iv fluids
