HTN in pregnancy Flashcards
How common in HTN in pregnancy ?
10-15% of pregnancies are affected (very common)
What percentage of primigravid (1st pregnancy) women are affected by pre-eclampsia (PET)?
- 10% are affected by mild PET
- 1% are affected by severe PET
What is the commonest cause of elective (medically induced) prematurity i.e. needing to have the baby born before premature due to risks to mother or baby?
PET
Describe the changes to BP during pregnancy and why they occur
- BP initially falls during early pregnancy reaching its lowest point at 22-24 weeks. After this is steadily rises
- This is because pregnancy causes vasodilation which results in a decreased SVR, there is an increase in CO but it is outmatched.
Note BP = SVR x CO
Following delivery of the baby what happens to the mothers BP ?
- It falls initially but then rises and peaks at days 3/4 postnatally
- By 6 weeks postnatally BP should be back to normal (easy to remember because puerperium i.e. when things are returning to normal only lasts 6 weeks)
How is HTN diagnosed in pregnancy ?
- By a BP of ≥ 140/90 on 2 occasions, followed by ambulatory BP monitoring or home BP monitoring if they cant use ABPM to confirm diagnosis
- OR by BP > 160/110 once, if severe BP (i.e. > 160/110) then consider starting on anti-HTN immediately without waiting for ABPM or HBPM
State the classifications for the severity of HTN
- Mild HTN = 140/90 → 149/99
- Moderate HTN = 150/100 → 159/109
- Severe HTN = ≥ 160/110
What are the 3 HTN disorders in pregnancy ?
- Pre-exisiting (chronic/essential) HTN
- Pregnancy induced HTN (gestational)
- Pre-eclampsia (PET)
Define what pre-existing (chronic/essential) HTN is in pregnancy
It is HTN present at booking or < 20 weeks (basically they had it prior to pregnancy because BP should be decreasing during this part of pregnancy)
Define what pregnancy induced HTN is
New HTN presenting > 20 weeks into pregnancy without any significant proteinuria
What secondary causes should you consider for pre-exisiting (chronic/essential) HTN in pregnancy ?
Renal, cardiac, cushings, conn’s, phaechromocytoma
When is pre-exisiting HTN in pregnancy often diagnosed ?
- It is often actually diagnosed prior to pregnancy
Note if it doesn’t resolve within 3 months post-delivery then can be retrospectively diagnosed as pre-exisiting HTN
What are the risks of HTN in pregnancy ?
- PET
- IUGR
- Placental abruption
What are the characteristic features of pregnancy induced HTN ?
Occurs during the second half of pregnancy and it resolves within 6/52 post delivery
The rate of recurrence of pregnancy induced HTN is high in subsequent pregnnacies - T or F?
True
Define what PET is
It is a pregnancy specific multi-system disorder with unpredictable, variable & widespread maniifestations
What are the characteristic features of PET ?
- New HTN after 20 weeks + Significant proteinuria
- +/- oedema as it is non-specific
Describe the pathogenesis of PET
- The primary defect is failure of trophoblastic invasion of spinal arteries
Spinal arteries proide blood to the interoplacental junction (from mother), normally you get cytotrophoblastic invasion which destroys some of the tunica smooth muscle allowing spiral arteries to open up and become high capacity, low resistance vessels
But in PET you get lack of cytotrophoblastic invasion ==> spiral arteries fail to adapt into high capacity low resistance vessels ==> they are narrower causing higher pressure & decreased flow to placenta ==> widespread endothelial damage & dysfunction ==> endothelial activation occurs causing increased capillary permeability, expression of CAM, prothrombotic factors, platelet aggregation and vasoconstriction
What are the symptoms of PET ?
- Headache
- Visual disturbance
- Epigastric / RUQ pain
- Nausea / vomiting
- Rapidly progressive oedema
What are the signs of PET ?
- HTN
- Proteinuria
- Oedema
- Abdominal tenderness (RUQ/epigastric region)
- Disorientation
- Small for Gestational Age (SGA) Fetus
- Intra uterine fetal death
- Hyper-reflexia / involuntary movements / clonus
How is significant proteinuria diagnosed in pregnancy ?
- Use reagent strip reading or spot urinary protein:creatinine ration
- If strip used & 1+ of protein then use spot urinary protein:creatinine ratio
Diagnose significant proteinuria if ≥ 0.3g/l or ≥0.3g/24hr (second is only if a 24hr urine collection is used which is a worse test)
List the potential complications of PET
- Fetal: prematurity, intrauterine growth retardation, IUD, placental abruption
- CNS: Eclampsia, HTN encephalopathy, intracranial haemorrhage, cerebral oedema, cortical blindness, CN palsy
- Cardiac failure
- Hepatic rupture
- Acute renal failure
- Multi-organ failure
- HELLP syndrome
- DIC
- Pulmonary oedema ==> ARDS
- Pulmonary embolism
What is HELLP syndrome and what is the management of it ?
It consists of:
- Haemolysis = destruction of RBC
- Elevated Liver enzymes
- Low Platelets
The signs and symptoms are pretty much the same as PET
It carries with it significant mortality (up to 30%), definitive management is to deliver the baby, however if delivery can be held off then corticosteroids for lung maturation and MgS04 for neuroprotection can be given for the baby
What investigations in antenatal care should be carried out for a pregnant women with HTN or PET?
- Bloods - FBC, Us&Es, LFT’s. serum urate, coagulation screen
- Urine PCR (protein:creatinine ratio)
- CTG
- U/S - fetal biometry (measuring size), AFI, doppler studies
Following initial investigations assessment of HTN or PET what follow-up investigations are required for someone with mild/moderate HTN?
- Carry out U/S: fetal biometry, AFI and doppler studies (umbilical artery doppler velocimetry) between weeks 28-30 and 32-34
- If normal don’t repeat after 34 weeks.
- Only carry out CTG if fetal activity is abnormal e.g. reduced
Following initial investigations assessment of HTN or PET what follow-up investigations are required for someone with severe HTN or PET ?
- Don’t repeat CTG > weekly and don’t repeat U/S fetal biometry, AFI or doppler studies > every 2 weeks
(so think this is saying do is weekly and every 2 weeks roughly)
What iextra nvestigations should someone at high risk of PET receive during their pregnancy ?
Carry out U/S - fetal biometry, AFI & doppler studies between 28-30 weeks & repeating 4 weeks later
List the moderate and high risk factors for PET and then state when and what prophylactic treatment can be given
Women with ≥ 2 moderate or ≥ 1 high risk factor for PET should receive 75mg of aspirin from 12 weeks until birth
What scan can be done to help predict development of PET in a pregnancy and when is it done during antenatal care ?
- A maternal uterine artery doppler done between 20-24 weeks
- If notching seen on scan then greater risk of PET
When should a pregnant women be referred up to the antenatal day care unit (AN DCU)?
- BP ≥ 140/90
- (++) proteinuria
- oedema
- symptoms - esp persistent headache
After being referred up to the AN DCU when should a pregnant women be admitted ?
- BP >170/110 OR >140/90 with (++) proteinuria
- Significant symptoms - headache / visual disturbance / abdominal pain
- Abnormal biochemistry
- Significant proteinuria - >300mg / 24h
- Need for antihypertensive therapy
- Signs of fetal compromise
When a pregnant women is admitted after being assessed at the AN DCU what assessements/monitoring should be carried out ?
- Blood Pressure - 4 hourly
- Urinalysis - daily
- Input / output fluid balance chart
- Urine PCR - if proteinuria on urinalysis
- Bloods - FBC, U&Es, Urate, LFTs. Minimum X2 per week
When should treatment of HTN in pregnancy be provided and what is the BP targets for treatment ?
- Treat if BP > 150/100.
- A BP > 170/110 requires immediate treatment
Aim for BP controlled between 140-50/90-100
What is the treatment of HTN in pregnancy (also the management of PET) ?
- 1st line = Labetalol (avoid in asthma)
- 2nd line = nifedipine (can give bad headaches) or methyldopa
- 3rd line = Hydralazine or doxazocin
In the treatment of HTN in pregnancy what drugs should you avoid/stop ?
Any ACEi/ARBs
What should you be careful of when using methyldopa in pregnancy for HTN ?
It can exacerbate depression so be careful in women with mental illness history
Of the hypertensive drugs used in pregnancy which one is not recommended in breastfeeding women?
Doxasocin
Go over these points for considering when to deliver when a women develops PET
- Only cure for PET is birth
- Consider expectant management if the baby is pre-term
- Steroids for fetal lung maturation may be needed
- Most mothers delier within 2wks of diagnosis of PET
What are the indications for birth in PET ?
- Term gestation
- Inability to control BP
- Rapidly deteriorating biochemistry / haematology
- Eclampsia
- Other Crisis
- Fetal Compromise - abnormal Ultrasound or CTG
Define what eclampsia is
This is tonic clonic (grand mal) seizures occurring with features of PET
Is it common for women to develop the seizures of eclampsia before onset of HTN/proteinuria ?
Yes 1/3rd will have a seizure before the development of HTN/proteinuria
What age group of women is eclampsia more common in ?
Teenagers
Define what severe PET is
This is BP > 160/110 + proteinuria
OR BP > 140/90 + proteinuria plus one more of:
- Seizures
- Visual disturbances
- Clonus
- Headache or epigastric pain
- Papilloedema
- Liver tenderness or HELLP
Outline the management of severe PET/eclampsia
- Control BP
- Stop / Prevent Seizures
- Fluid Balance
- Delivery
How is the BP controlled in servere PET/eclampsia ?
1st line = IV labetalol + IV hydralazine
How do you stop/prevent the seizures in severe PET/eclampsia ?
- 1st line = IV MgSO4
- 2nd line = if further seizures give more IV MgSO4
- 3rd line = IV diazepam
How is fluid balance controlled in severe PET/eclampsia ?
- Fluid restrict to 80ml/hr
Note - main cause of maternal death is pulmonary oedema (leading to acute resp distress) and oliguria which occurs in 30% of cases doesn’t need intervention
What are the signs/symptoms of acute resp distress syndrome ?
- Laboured rapid breathing
- Mental confusion
- Fatigue/ weakness
- Fast pulse
- Low BP
What is the delivery treatment of severe PET/eclampsia ?
- Aim for vaginal birth if possible
- Control BP
- Give Epidural anaesthesia
- Continuous electronic fetal monitoring
- Avoid ergometrine - due to its hypertensive effect
- Caution with IV fluids
