Hypertension in pregnancy Flashcards
Whats the incidence of hypertension in pregnancy? What proportion of this develops in pregnancy and what proportion is chronic?
7-10% pregnancies.
70% gestational HTN/pre-eclampsia, 30% chronic HTN
Give 2 risk factors for gestational HTN:
- young female (x3 risk)
- African/Caribbean (x2 risk)
After what point in the gestational period would gestational HTN develop? What systolic and diastolic measurements define it?
New HTN after the 20th week of gestation.
Systolic >140
Diastolic >90
What degree of proteinuria is present in those with gestational HTN?
No or little proteinuria
What defines pre-eclampsia?
- New HTN after 20th week gestation (earlier in trophoblastic disease)
- Proteinuria
- Oedema (not part of definition however)
What differs eclampsia from pre-eclampsia?
Eclampsia has the features of pre-eclampsia with generalised tonic-clonic seizures.
What is the diagnostic criteria for pre-eclampsia?
Gestational HTN:
- Systolic >140
- Diastolic >90
Proteinuria:
- > 0.3g protein/24hrs
- > 2+ on urine dip
How should BP be measured during the diagnosis of gestational HTN to ensure accurate results?
- Sitting position (not supine as compression of the IVC may be present
- Cuff at heart level
What defines severe pre-eclampsia?
(one or more)
1) BP:
- Systolic >160
- Diastolic >110
2) Proteinuria:
- >0.5g/24hr, over 3+ urine dip
3) Oliguria
4) CNS: visual changes, headache, scotomata (partial loss of vision)
5) Pulmonary oedema
6) Epigastric or RUQ pain
7) Impaired LFTs
8) Thrombocytopenia: <100,000
9) IUGR
10) Oligohydramnios
What is the diagnosis of pre-eclampsia upon chronic HTN?
Two situations:
A) HTN and no proteinuria <20 weeks: New onset proteinuria after 20 weeks is diagnostic
B) HTN and proteinuria <20 weeks: Sudden increase in proteinuria Sudden increase in HTN when it is normal well controlled Thrombocytopenia (<100,000) Abnormal ALT/AST
Outline the pathogenesis of pre-eclampsia:
(draw a flow diagram)
1) Predisposition: Diabetes, parity, hypertension
2) Failure of conversion of spiral arteries to vascular sinus’ due to poor trophoblasts infiltration
3) Placental ichaemia
4a) Can lead to IUGR
or
4b) Placenta produces thromboplastins (cause coagulation through conversion of prothrombin to thrombin) [released due to hypoxic/ischaemic conditions in the placenta] causing DIC and renin = vascoconstriction
5) (Following 4b) Poor renal perfusion + damage to endothelium in blood vessels:
- Hypertension
- Proteinuria
- Oedema (due to protein leakage into extra cellular spaces
6a) Which results in pre-eclampsia.
6b) If untreated, this may develop into further poor renal perfusion and then eclampsia.
What does humoral control mean?
It means control of hormone release in response to changes in extracellular fluids
What does autocoid control mean?
They act as local hormones and messengers from one local cell to its neighbours
How long should it take for gestational HTN to resolve after birth?
~12weeks
What is the endometrium known as during pregnancy?
Decidua
What does the release of thromboplastins cause?
Clotting through the body
In addition to HTN and proteinuria, what needs to be present to confirm pre-eclampsia?
(evidence of end organ damage):
- Kidney damage (^CK)
- CNS symtoms: headache, visual symptoms
- ^ liver enzymes (ALT/AST)
- Poor clotting factors (thrombocytopenia)
What is the Rx/cure for pre- eclampsia?
Delivery (as placenta is the source of the issues):
- if >37 weeks, then deliver the baby
- if <37 weeks then only consider delivering if pre-eclampsia is severe
What are women with pre-eclampsia started on during labour and why?
- Magnesium sulfate (antiepileptic medication)
(caution in renal failure)
This is because eclampsia is at highest risk: just before delivery, during labour and 24hours after delivery.
Give two safe hypertensives which are able to be used in pregnancy:
- Hydralazine
- Labetolol
(if HTN is severe, can also use: Nifedipine or sodium nitroprusside)
What renal abnormalities could be present during pre-eclampsia?
- GFR decreased
- raised uric acid levels
- Proteinuria
- Impaired Na excretion and suppression of RAS
What live complications could be present in pre-eclampsia?
HELLP syndrome:
- Haemolysis
- Elevates ALT and AST
- Low Platelet count
What neurological complications could be present in pre-eclampsia?
CNS:
- Eclampsia
- Headache and visual disturbances
- Scotomata
- Cortical blindness
Give 4 symptoms of pre-eclampsia:
- Visual disturbances
- Headache similar to migraine
- epigastric pain
- rapid weight gain
