Hypertension in Pregnancy Flashcards
what % of pregnancies does HT usually affect?
10-15%
how many primigravid (1st baby) mothers experience pre-eclampsia?
mild PET = 10%
severe PET = 1%
what is eclampsia?
seizure as a result of severe pre-eclampsia
high risk of maternal death
when in pregnancy do changes in CV system usually occur?
first 12 weeks
what CV changes does a mother experience in pregnancy?
increased plasma volume and CO
peripheral vascular resistance decreases
what trends in BP and heart rate are thought to occur in 2nd and 3rd trimester of pregnancy?
2nd trimester = dip in BP (less marked than previously thought)
3rd trimester (increase in HR by around 7bpm)
what is the quantitative definition of hypertension?
> 140/90mmHg on 2 occasions
160/110mmHg once
*some areas of world use increase of >30/15mmHg since 1st trimester
what different types of HTN can result during pregnancy?
pre-existing hypertension
pregnancy induced hypertension (PIH)
pre-eclampsia
what is the difference between PIH and PET?
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 causes
cardiac causes
endocrine causes - cushings, conns, phaeochromocytoma
what does pre-existing HTN increase the risk of in pregnancy?
PET
IUGR
placental abruption
when does PIH normally present and resolve?
normally presents 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 or false?
true
patient may experience high BP, proteinuria and oedema but not feel unwell
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 and 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 PET affect the liver to cause disease?
epigastric / RUQ pain
abnormal liver enzymes
hepatic capsule rupture
HELLP syndrome (haemolysis, elevated liver enzyme, low platelets)
what complications can PET cause which are specific to the placenta?
foetal 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 PET?
abdominal tenderness disorientation SGA foetus intrauterine foetal death hyper reflexia / involuntary movement / clonus (these signs develop prior to eclampsia seizure)
what investigations should be carried out throughout pregnancy if a mother has PET?
serum urate LFTs FBC coagulation screen cardiotocography US
women who develop PET in subsequent pregnancies experience greater severity than women in their first pregnancy - true or false?
true
what conditions in a mothers PMH may increase the risk of PET in pregnancy?
pre-existing renal disease pre-existing HTN diabetes connective tissue disease thrombophilias
when should low dose aspirin be started in pre-eclampsia?
commence before 16 weeks if at least 2 moderate risk factors or one high risk factors for PET
usually taken from 12 weeks until birth (150mg dose Tayside, but NICE = 75mg)
how may pre-eclampsia be predicted from a maternal uterine artery doppler?
high resistance and low flow found in pre eclampsia appears as low flow / minimal colour on doppler US
when should a mother with PET be admitted to hospital?
BP >170/110 OR >140/90 with ++ proteinuria
significant symptoms - headache / visual disturbance / abdominal pain
abnormal biochemistry
significant proteinuria - >300mg/24 hours
need antihypertensive therapy
signs of foetal compromise
how should mothers suffering from PET 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/week)
what are moderate risk factors of PET?
first pregnancy age >40 pregnancy interval >10 years BMI >35 at first visit FH of pre-eclampsia multiple pregnancy
what are high risk factors of PET?
hypertensive disease during previous pregnancy CKD autoimmune disease - SLE, APS type 1 or 2 DM chronic hypertension
when are most women treated for hypertension?
BP >150/100mmHg
BP >170/110mmHg = immediate!
control of BP does not reduce risk of developing PET nor does it cure PET (only cure is delivery of baby)
what agents can be used to treat HTN in pregnancy and when are these contraindicated?
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 PET 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 PET 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 hour 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” - 80ml/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
