Hypertensive Disorders in Pregnancy Flashcards
When does blood pressure fall to a minimum level during pregnancy?
when does it go back to ‘normal’
2nd trimester - by about 30/15mmHg because of reduced vascular resistance
By term, blood pressure rises again to pre-pregnant levels
What is the cause of hypertension due to pre-eclampsia?
increase in systemic vascular resistance
Excretion of what substance is increased in normal pregnancy?
protein (still less than 0.3g/24 hours in the absence of renal disease)
What is pregnancy induced hypertension?
When the blood pressure rises above 140/90mmHg after 20 weeks
What are the causes of pregnancy induced hypertension?
Pre-eclampsia or transint hypertension
What is pre-eclampsia?
Pre-eclampsia refers to new high blood pressure (hypertension) in pregnancy with end-organ dysfunction, notably with proteinuria (protein in the urine). It occurs after 20 weeks gestation
What is the difference between pre-eclampsia and gestational hypertension?
Gestational hypertension - new hypertension presenting after 20 weeks without proteinuria
HOWEVER, occasionally, proteinuria is absent in pre-eclampsia, particularly in early pregnancy
What is pre-existing hypertension
When blood pressure is >140/90mmHg before pregnancy or before 20 weeks gestation, or the woman is already on hypertentive treatment
May be primary hypertension or secondary to renal or other disease - may also be pre-existing proteinuria because of renal disease
What is pre-eclampsia?
Multisystem syndrome that usually manifests as new hypertension after 20 weeks with significant proteinuria
specific to pregnancy, of placental origin and cured only be delivery
What are the effects of pre-eclampsia?
Blood vessel endothelial cell damage leads to vasospasm, increased capillary permeability and clotting dysfunction - both the foetus and mother are a risk
What are the two phenotypes of pre-eclampsia?
Early onset - that which causes complications before 34 weeks: typically the foetus is growth restricted
Late onset - manifest at any later gestation - not usually associated with growth restriction, although fetal death and damage may occur
What is the first step in the pathophysiology of pre-eclampsia?
Poor placenta perfusion
What happens in normal pregnancy to allow adequate placenta perfusion?
Trophoblastic invasion of spiral arterioles leads to vasodilation of vessel walls to allow adequate placenta perfusion
How is pre-eclampsia caused?
Pre-eclampsia is caused by high vascular resistance in the spiral arteries and poor perfusion of the placenta. This causes oxidative stress in the placenta, and the release of inflammatory chemicals into the systemic circulation, leading to systemic inflammation and impaired endothelial function in the blood vessels.
What is pre-eclampsia as opposed to severe pre-eclampsia?
Pre-eclampsia - new hypertension presenting after 20 weeks with significant proteinuria
severe pre-eclampsia - pre-eclampsia with severe hypertension and/or with symptoms and/or biochemical and/or haematological impairment
What are the classifications of hypertension?
Mild - 140/90 - 149/99mmHg
Moderate - 150/100 - 159/109mmHg
Severe >160/110mmHg
What are the classifications of pre-eclampsia?
mild/moderate: pre-eclampsia without severe HTN and no symptoms and no biochemical or haematological impairment
Severe- pre-eclampsia with severe HTN and/or with symptoms, biochemical or haematological impairment
Early: <34 weeks
Late >34 weeks
Describe the epidemiology of pre-eclampsia?
Affects 6% of nulliparous women
less common in multiparous women unless additional risk factors are present
15% recurrence risk
this is up to 50% if there has been severe pre-eclampsia before 28 weeks
What are the predisposing factors for pre-eclampsia?
High-risk factors are: Pre-existing hypertension Previous hypertension in pregnancy Existing autoimmune conditions (e.g. systemic lupus erythematosus) Diabetes Chronic kidney disease
Moderate-risk factors are: Older than 40 BMI > 35 More than 10 years since previous pregnancy Multiple pregnancy First pregnancy Family history of pre-eclampsia
Women are offered aspirin from 12 weeks gestation until birth if they have one high-risk factor or more than one moderate-risk factors.
What are the clinical features of pre-eclampsia?
Headache Visual disturbance or blurriness Nausea and vomiting Upper abdominal or epigastric pain (this is due to liver swelling) Oedema Reduced urine output Brisk reflexes
Hypertension = usually the first sign - massive oedema is also found in pre-eclampsia, not postural or of sudden onset
presence of epigastric tenderness is suggestive of impending complications
urine dipstick testing for protein should be considered part of clinical exam
What do the following indicate:
trace
Dipstick 1+ for protein
Dipstick >2+ for protein
PCR >30mg/nmol
24h collection >0.3g/24h
trace - seldom significant
1+ - possible significant proteinuria: quantify
> 2+ - significant proteinuria likely: quantify
PCR >30mg/nmol: confirmed significant proteinuria
24h collection: confirmed significant proteinuria
What are the maternal complications of pre-eclampsia?
ECLAMPSIA
CV haemorrhage
Fluid overload
Renal failure
Liver failure - rupture/ HELPP
PE - give enoxaparin
DIC - prevent
placental abruption
What is eclampsia?
grand mal seizure resulting from cerebrovascular vasospasm - mortality can result from hypoxia and concomitant complications of severe disease
Treatment: magnesium sulphate and intensive surveillance for other complications
What Is the cause of cerebrovascular haemorrhage?
failure of cerebral blood flow auto regulation at MABP >140mmHG
What liver and coagulation problems result from pre-ecalmpsia?
HELLP syndrome
Haemolysis
Elevated Liver enzymes
Low Platelets
DIC, liver failure and liver rupture may also occur
treatment Is supportive and includes magnesium sulphate prophylaxis against eclampsia - liver infarction or subscapsular haemorrhage may occur
How is renal failure identified?
careful fluid balance monitoring and creatine measurement
Haemodialysis is required in severe cases
What is pulmonary oedema as a result of pre-eclampsia treated with?
oxygen and furosemide and assisted ventilation may be required - ARDS may develop
What are the fetal effects of pre-eclampsia?
perinatal mortality and morbidity of the foetus = increased
5% stillbirths
10% preterm deliveries accounted for by pre-eclampsia
growth restriction (early onset)
at term - affects foetal growth less, but is still associated with increased morbidity and mortality
at all gestations, there is an increased risk of placental abruption
What investigations should be done for pre-eclampsia?
if bed stick urinalysis is +ve, the protein is quantified - 24hr urine or PCR is used
30mg/nmol or 0.3g/24hr protein excretion - proteinuria may be absent in early disease and testing for proteinuria is repeated
Blood tests - elevation of uric acid. HB often high and rapid fall in platelets due to aggregation on damaged endothelium - impending HELLP
Rise IN LFTs (ALT) - impending liver damage
LDH levels rise
Renal function mildly impaired - rising creatinine
USS
What is the most common screening test for early prediction?
uterine artery Doppler at 20 weeks - sensitivity for PE at any stage in pregnancy is about 40% for a 5% screen-positive rate
What is the screening test for late prediction of PE?
placental growth factor (PlGF) testing on one occasion during pregnancy in women suspected of having pre-eclampsia.
Placental growth factor is a protein released by the placenta that functions to stimulate the development of new blood vessels. In pre-eclampsia, the levels of PlGF are low.
What is the prevention of pre-eclampsia?
low-dose aspirin (75mg) before 16 weeks (evening) reduces the risk of pre-eclampsia and is now NICE recommended.
High dose vitamin D with Ca2+ supplementation might also be effective
What is the management of pre-eclampsia?
Assessment - day assessment
sFlt-1:PIGF ratio
pts without proteinuria and with mild/moderate hypertension are usually managed as outpatients - BP and urinalysis repeated 2/week - USS 2-4 weeks unless suggestive of foetal compromise
Admission
Drugs
What are the indications for admission with pre-eclampsia?
Necessary with severe HTN and presence of proteinuria - if hypertension absent but proteinuria, they should be admitted
Assessment using sFlt-1:PIGF assay may determine which women are most at risk and should be admitted
What drugs are used in pre-eclampsia?
Labetolol is first-line as an antihypertensive
Nifedipine (modified-release) is commonly used second-line
Methyldopa is used third-line (needs to be stopped within two days of birth)
Intravenous hydralazine may be used as an antihypertensive in critical care in severe pre-eclampsia or eclampsia
IV magnesium sulphate is given during labour and in the 24 hours afterwards to prevent seizures
Fluid restriction is used during labour in severe pre-eclampsia or eclampsia, to avoid fluid overload
Steroids if delivery before 36 weeks
What are the indications of antihypertensives?
Which drugs are used?
Given if BP reaches 150/100mmHg - labetalol maintenance is recommended
Oral nifedipine for initial control with IV labetalol as 2nd line with severe hypertension
aim for BP is 140/90
What Is magnesium sulphate used for in pre-eclampsia?
used in both treatment and prevention - IV loading dose followed by IV infusion
increased cerebral perfusion so treats underlying pathology of eclampsia
toxicity is severe, resulting respiratory depression, hypotension, loss of patellar reflex
What are steroids used for in pre-eclampsia?
promote foetal pulmonary maturity if the gestation is <34 weeks
At what gestation should women with pre-eclampsia be delivered?
36 weeks
At what gestation should women with gestational hypertension be delivered?
40 weeks as usual , as long as foetal compromise is monitored
What are the indications for C-section in PE?
Before 34 weeks
If severe growth restriction
abnormal CTG
What things need to be given in labour for PE?
Induction - prostaglandin
anti-hypertensives
maternal pushing avoided in 2nd stage if BP is 160/110
oxytocin instead of ergometrine - 3rd stage as latter can increase BP
What is the postnatal care for PE?
Enalapril (first-line)
Nifedipine or amlodipine (first-line in black African or Caribbean patients)
Labetolol or atenolol (third-line)
What is pre-existing hypertension in pregnancy?
When BP is already treated or exceeds 140/90 before 20 weeks
Who is pre-existing hypertension more common in?
Older women
Obese women
Positive FH
Developed HTN on COCp
What is secondary HTN commonly associated with?
Obesity Diabetes Renal disease - ADPKD, renal artery stenosis or chronic pyelonephritis PCC Cushing's syndrome Cardiac disease Coarctation of the aorta
What investigations are done for pre-existing HTN?
Renal function assessed and renal USS performed
PCC excluded
quantification of any proteinuria and uric acid level allow comparison in later pregnancy
Why are ACE-i not used in preganancy?
Teratogenic and affect foetal urine production
What drugs are normally used to treat maternal HTN in pregnancy?
Labetalol
Nifedipine
Why might treatment not be needed in 2nd trimester?
Physiological fall in BP
What other measures are put in place for pre-existing maternal HTN?
low dose aspirin advised - 75mg
screening using uterine artery doppler and additional antenatal visits are usual
Delivery: 38-40 weeks
