Hypertensive Disorders In Pregnancy Flashcards
How is blood pressure calculated?
BP=COxTPR/SVR
What happens to BP in preganncy?
Cardiac output increases by 40%
SVR decreases by 50%
Overall BP falls
What happens to the BP in the second trimester?
Falls by 30/15mmHg
What happens to the BP at term?
Rises to pre-pregnant level
What happens to protein excretion in pregnancy?
It increases -> up to 0.3g/24 hours
Normal is 0.15g/24 hours
What are the classes of HTN in pregnancy according to the RCPI 2016?
Mild, moderate and severe
What is mild HTN in pregnancy?
> 140/90
What is moderate HTN in pregnancy?
> 150/100
What is severe HTN in pregnancy?
> 160/110
How is HTN diagnosed in pregnancy?
Based on 2 measurements hours apart
If severe HTN then 15mins apart
What are the 2 broad categories of HTN in pregnancy?
Chronic HTN
Pregnancy induced HTN
What is chronic HTN in pregnancy?
HTN (+/- medication) before pregnancy
or
HTN before 20 weeks gestation
Why is chronic HTN important in pregnancy?
6 fold increased risk of pre-eclampsia
Can have existing protein due to HTN
Can someone with chronic HTN also have pre-eclampsia?
Yes superimposed pre-eclampsia possible
What are the 3 types of HTN in pregnancy?
Gestational HTN
Pre-eclampsia
Eclampsia
What is Gestational HTN?
New HTN >20 weeks no proteinuria
Is gestational HTN a risk factor for pre-eclampsia?
15-25% will develop pre-eclampsia
50% if <32 weeks
What is pre-eclampsia?
HTN + 1 or more new conditions >20 weeks
What is eclampsia?
Tonic/clonic seizure in a/w/ features of pre-eclampsia
What drug is the first line agent for HTN in pregnancy?
Labetalol (beta blocker)
Who should not be given Labetalol to manage HTN in pregnancy?
Asthmatics - give nifedipine a calcium channel blocker
What older anti-HTN is still sometimes used in pregnancy?
Methyldopa
What are the issues with Methyldopa in pregnancy?
Takes a while to take effect
Causes sedation and low mood so recommend stopping 2 days before delivery
What is the definition of pre-eclampsia?
Multisystem disorder of pregnancy usually manifest by HTN (>20 weeks) and proteinuria
What is the NICE guidelines 2019 definition of pre-eclampsia?
New onset hypertension after 20 weeks with 1 or more of:
* proteinuria (30mg/mmol)
* maternal organ dysfunction
* uteroplacental dysfunction
What is the RCPI 2016 definition of pre-eclampsia?
New hypertension after 20 weeks with signs of proteinuria or maternal organ dysfunction or growth restriction
What is the pathophysiology behind pre-eclampsia
- Increased vascular permeability
- Vasospasm/constriction
- Clotting dysfunction
Which cause the manifestations and complications of pre-eclampsia
What is the pathophysiology of pre-eclampsia?
Placental disease (not foetal – can happen with moles, not uterine – can happen with intraabdominal pregnancy).
Incomplete trophoblastic invasion and microvascular disease (similar to atherosis of arterial disease elsewhere)
Spiral arteries are the uterine arteries that are dilated under the action of the invading trophoblast.
Endothelial cells are the layer of cells that line the interior surface of blood vessels
What are the stages of the pathophysiology of pre-eclampsia?
Stage 1: (< 20 weeks)
Incomplete trophoblastic invasion+spiral atheroma cause decreased uteroplacental flow.
? Due to altered immune responses
Stage 2: (> 20 weeks)
Ischaemic placenta by exaggerated maternal inflammatory response cause endothelial cell dysfunction leading to vasoconstriction, vascular permeability and clotting dysfunction.
What is the difference between early onset and late onset pre-eclampsia?
What will been seen on a uterine artery Doppler with pre-eclampsia?
Failure to develop this low resistance uterine circulation can be picked up
Reduced flow of uterine artery - ie spiral arterioles haven’t dilated (if they had dilated you would have lost the notch that’s seen in nonpregannt uterine artery Doppler)
When can uterine artery Doppler pick up abnormal waveforms? (And 3 things it can predict)
20-23 weeks which can predict adverse outcomes
Eg pre-eclampsia, IUGR, abruption
How else can pre-eclampsia be predicted?
Blood test for the ratio of sFlt-1:PIGF may be useful in later pregnancy to predict which women with hypertension will develop pre-eclampsia, but not routinely used to date.
Nice guidelines 2019 mentions this (placental growth factor testing to help rule out pre-eclampsia)
What is the epidemiology of pre-eclampsia?
2-3% of pregnancies (5-7% nullips)
What is the recurrence rate of pre-eclampsia?
15% recurrence (up to 50% if pre-eclampsia <28 weeks)
What are risk factors of pre-eclampsia? (7)
Nulliparity
Personal or family history of pre-eclampsia
Long gap between pregnancies (>10yrs)
Microvascular disease:
- HTN, renal disease, diabetes, sickle cell disease, autoimmune (incl. antiphospholipid)
Large placenta:
Twins, hydrops, molar pregnancies
Extremes of maternal age (esp >40)
Raised maternal BMI (>35)
What is hydrops?
Accumulation of fluid in 2 or more foetal spaces, a lot of hydrops comes out of anaemia
What are some of the high risk risk factors for pre-eclampsia? (5)
HTN, CKD, DM, autoimmune disease
Previous history
What are some of the moderate risk risk factors for pre-eclampsia? (5)
- Nulliparity
- pregnancy interval >10yrs
- family history of pre-eclampsia
- multiple pregnancies
- BMI>35
- age>40
What can be done to help prevent pre-eclampsia based on risk factors?
If 1 high risk or 2 moderate risk factors should take 75-150mg aspirin from 12 weeks til delivery to prevent pre-eclampsia
What are the clinical features of pre-eclampsia usually?
Asymptomatic
What are the symptoms of pre-eclampsia? (3x4)
Headaches: ? Cerebral vasospasm, oedema, or hypertensio
Reversal cortical blindness due to cerebral oedema, due to retinal artery spasm or clots
Epigastric/RUQ pain: liver capsule oedema or liver ischaemia
Renal: decreased plasma volume or ischaemia ATN
What are the symptoms of pre-eclampsia?
Headaches: ? Cerebral vasospasm, oedema, or hypertensio
Reversal cortical blindness due to cerebral oedema, due to retinal artery spasm or clots
Epigastric/RUQ pain: liver capsule oedema or liver ischaemia
Renal: decreased plasma volume or ischaemia ATN
What clinical features of pre-eclampsia are seen on examination?
- HTN
- proteinuria
- massive/sudden/not postural oedema (ie not just in lower limbs also in hands and face)
What is usually the first sign of pre-eclampsia on examination?
HTN