Hypertension In Pregnancy Flashcards
Does BP rise or fall during early pregnancy?
Falls until 24 weeks, particularly the diastolic, due to a fall in vascular resistance
After 24 weeks does BP rise or fall?
It rises - due to an increase in stroke volume
It then falls again after delivery, peaking again at day 3-4 postpartum
Hypertension in pregnancy is usually defined as…
Systolic > 140 or diastolic >90
Or an increase above booking readings of >30 systolic or >15 diastolic
How is it classified?
Pre-existing hypertension
Pregnancy induced hypertension
Pre-eclampsia
How is pre-existing HTN defined?
A history of HTN or elevated BP before 20 weeks gestation
No proteinuria
No oedema
What do those with pre-existing HTN have a higher risk of developing?
Pre-eclampsia (doubled if on treatment)
Fetal growth restriction
Placental abruption
If the pre-existing HTN is a new finding, other causes of HTN should be excluded such as…
Coarctation Renal artery stenosis Cushing’s Conn’s Phaeochromocytoma
Those with pre-existing HTN should stop what medication preconception?
ACEi, ARBs, thiazides - risk of congenital abnormalities
Change these to labetalol or methyldopa
In those with pre-existing HTN, what medication should be given from conception until birth?
Aspirin 75mg/24h
What BP is considered a medical emergency?
160/110
In those with pre-existing HTN, what should be done every 4 weeks from 28 weeks?
Fetal USS to assess for fetal growth, amniotic fluid volume, umbilical artery Doppler
During labour, if there is severe HTN that does not respond to treatment, what should be advised?
Operative delivery
Oxytocin alone at 3rd stage - ergometrine causes severe HTN risking stroke
What should merhyldopa be changed to post delivery?
Another hypertensive - risk of postnatal depression
Pregnancy induced HTN affects what percentage of pregnancies?
6-7%
How is PIH defined?
HTN in the second half of pregnancy
Absence of proteinuria, oedema or other features of pre eclampsia
Resolves following birth - typically 1 month
What are those with PIH at future risk of?
HTN
Pre-eclampsia
What percentage of those with PIH go in to develop pre-eclampsia?
25%, so should be kept under surveillance
How is PIH managed?
Check urine and BP weekly if mild 140/90-149/99 but start treatment e.g with labetalol if >150/100 and check urine and BP twice weekly
If >160/110 admit to hospital, measure BP QDS, urgent daily, FBC, U&E, AST/ALT and bilirubin at presentation and weekly
If HTN mild do fetal growth scans every 4 weeks, if severe and cannot stabilise on oral treatment make plans for delivery
Aim for delivery after 37w unless pre-eclampsia supervenes
What is pre-eclampsia characterised by?
HTN (>140/90) and proteinuria in pregnancy
Proteinuria = >30mg per 24 hours
Oedema may occur but it is now less commonly used as a criteria
Pre-eclampsia occurs after how many weeks?
20 and resolves within 6 weeks of delivery
What causes pre-eclampsia?
Primary defect = failure of trophoblastic invasion of spiral arteries leaving them vasoactive - properly invaded they cannot clamp down in response to vasoconstrictors (protects placental flow), so increasing BP partially compensates for this
Is pre-eclampsia a multisystem disorder?
Yes - it also affects hepatic, renal and coagulation systems
What risk factors are there for pre-eclampsia?
High risk: Previous pre eclampsia Chronic HTN or HTN in previous pregnancy CKD DM Autoimmune disease - SLE, APS
Moderate risk: Primigravida First pregnancy with new partner >10 years since last pregnancy >40y/o BMI > 35 FH Multiple pregnancy Molar pregnancy Uterine artery notching on USS
If 1 high risk/2 moderate risk factors for pre-eclampsia, what should be taken?
Aspirin 75mg from 12 weeks until delivery
What complications can occur with pre-eclampsia?
CNS: eclampsia, intracerebral haemorrhage/stroke
Renal: renal tubular necrosis (AKI)
Respiratory: pulmonary oedema
Liver: HELLP syndrome, liver capsule haemorrhage, liver rupture
Haematological: DIC, VTE
Placental: abruption (sudden spikes/rapid drop in BP)
How can one-eclampsia affect the fetus?
Stillbirth
Small for gestational age
Prematurity
What is HELLP syndrome?
Severe variant of pre-eclampsia
Haemolysis
Elevated Liver enzymes
Low Platelets
Liver enzymes usually rise first followed by drop in platelets, then haemolysis
What symptoms occur with pre-eclampsia?
In many cases = asymptomatic
Headache
Flashing lights, visual disturbance
Sudden increase in swelling - face, fingers, lower limbs
Abdominal pain (RUQ/epigastric) RUQ related to liver ischaemia, lower abdominal pain - placental abruption
Vomiting and nausea
Generally unwell
What signs are associated with ore-eclampsia?
HTN Proteinuria Non dependent oedema Hyperreflexia/clonus Confusion Reduced urine output IUGR Oligohydraminos Placental abruption Fits
What investigations are required with pre-eclampsia?
FBC - platelet count, anaemia if haemolysis
UandE, eGFR, protein-creatinine ratio, raised serum uric acid
LFTs
Coagulation profile
Fetal: growth velocity, wellbeing - amniotic fluid volume, CTG, Doppler
How is pre-eclampsia managed?
Depends on disease severity, gestation, speed of progression, presence of complications, fetal wellbeing
Large part = monitoring maternal and fetal wellbeing - regular B, urinalysis, bloods, fetal growth scans and CTG
VTE prevention - fluids and LMWH
Antihypertensives - reduce risk of maternal haemorrhagic stroke, do not alter disease course, guidelines suggest treating BP when >160/110 but many clinicians have lower threshold
Delivery - only definitive cure
When <35w gestation and delivery is considered in cases of pre eclampsia, what should be given to aid fetal lung development?
IM steroids
What are the main antihypertensives used in the treatment of pre-eclampsia?
Labetalol
Nifedipine (CCB)
Methyldopa (alpha agonist)
Emergency control of severe HTN:
IV labetalol, hydralazine
In severe or fulminant pre eclampsia, what should be given to prevent seizures?
Magnesium sulphate infusion
What post natal care is required in pre eclampsia?
It resolves after delivery of placenta
Monitor 24 hours post partum - still at risk of seizures
BP monitored daily for first 2 days
The need for antihypertensives reassessed
What is eclampsia?
Emergency Tonic clonic seizures plus pre-eclampsia Occurs in pregnancy or within 10 days of delivery At least 2 of: HTN Proteinuria Thrombocytopenia Raised transaminases Within 24hours or seizures
How is eclampsia managed?
ABCDE
IV access
Bolus 4mg magnesium sulphate plus continuous infusion (used to prevent and treatment seizures) 1g per hour over 24h
Repeated seizures treated with diazepam
Control HTN
Fluid balance, catheterise
If antenatal - deliver (likely c section)
Describe the pathophysiology of pre eclampsia
Development of abnormal placenta
Normally during pregnancy the spiral arteries dilated and develop into large uteroplacental arteries - can deliver large quantities of blood to fetus
In pre eclampsia these arteries become fibrous - causing them to narrow, so less perfusion to placenta
Hypoperfused placenta starts releasing pro inflammatory proteins - into mothers circulation. The endothelial cells that line mother’s vessels become dysfunctional and vasoconstrict.
This affects the kidneys by causing them to retain more salt
Local areas of vasospasm can lead to…
Oliguria, proteinuria - signs of glomerular damage
Blurred vision, scotoma
Liver injury and swelling - stretching of capsule causing RUQ pain and raised LFTs
Endothelial cell injury also causes: tiny thrombi in microvasculature - causing haemolysis
Endothelial injury causes increased permeability which leads to…
Generalised oedema
Pulmonary oedema - coughing, SOB
Cerebral oedema - headache, confusion, seizures
What is methyldopa contraindicated in?
Depression
