Hypertensive Disorders in Pregnancy Flashcards
(42 cards)
Define Hypertension?
Hypertension is defined as a systolic Blood Pressure over 140 or diastolic Blood Pressure over 90 mmHg, measured twice at least 4 hours apart; or >160 systolic or >110 diastolic on one occasion
What are the risk factors for Hypertensive Disorders in pregnancy?(8)
Extremes of age (<20, >35years)
Family history
Nulliparity
Multiple pregnancy
Preexisting diabetes
Preexisting body mass index >35
Previous pre-eclampsia
Gestational trophoblastic disease
What are the HTN disorders in Pregnancy.
Chronic hypertension
Gestational hypertension
Preeclampsia
Preeclampsia superimposed on chronic hypertension
Eclampsia
Define Chronic HTN
Elevated Blood Pressure of greater or equal to 140/90mmHg :
-Occurring before pregnancy
-Before or at 20 weeks of gestation
-Persistence of BPs 12 weeks postnatal
Why are women with high BPs before 20 weeks of pregnancy assumed to have pre existing or essential hypertension?
Because normally BPs fall in the first and second trimester
Define Gestational Hypertension?
New onset of BP ≥140/90 mmHg occurring after 20 weeks gestation, but without evidence of maternal end organ damage and only lasts up to 12 weeks after delivery.
Define Pre-eclampsia?
It is defined as gestational hypertension of at least 140/90 mmHg on two separate occasions measured at least 4 hours apart accompanied by one or more of the following new-onset conditions at or after 20 weeks gestation
What parameters are involved in Pre-eclampsia ?
-significant Proteinuria of at least 300mg in a 24 hour urine collection or at least 1 g/litre (1+ on urine dipstick).
-Maternal organ dysfunction
1.renal insufficiency
2. Liver involvement
3.neurological complications ( seizures, altered mental state, blindness, stroke). 4.Hematological complications i.e. thrombocytopenia, hemolysis.
5.Uteroplacental dysfunction
How is uteroplacental dysfunction noted?
By intrauterine growth restriction
What does Proteinuria in HTN indicate?
It indicates impaired renal function and by inference, impaired placental function with consequent threat to the fetus
Describe the normal physiology of the uteroplacental function.
Trophoblast cells invade the spiral arterioles within the first weeks of pregnancy and replace the smooth muscle of the walls of the vessel, thus converting them into wide bore, low resistance, large capacitance vessels.
How long does it take for the anatomical conversion of the maternal spiral arteries by the trophoblast cells.
2o weeks
By how much does the placental blood flow increase throughout pregnancy?
From 50ml/min in the first trimester to 500-750ml/min at term.
Describe the pathophysiology of pre-eclampsia?
There is an impairment of trophoblast to invade the myometrial segments of the spiral arteries.
Hence, spiral arteries retain some of their pre-pregnancy characteristics of being relatively narrow bore, of low capacitance and high resistance, and resulting in impaired perfusion of the fetoplacental unit.
This leads to the release of proinflammatory proteins that cause endothelial cell dysfunction causing vasoconstriction in different organs, leading to the manifestations of the syndrome
Describe the severe feature of pre-eclampsia.
-Severe hypertension e.g. a systolic blood pressure over 160 mmHg, or diastolic over 110mmHg with at least 2+ proteinuria. OR
-Moderate hypertension of at least 140mmHg systolic and 90 mmHg diastolic associated with any of: severe headache with visual disturbance; epigastric pain; signs of clonus; liver tenderness; platelet count falling to below 100; creatinine >100 mmol/litres; alanine amino transferase rising to above 50 IU/litres
What are the goals for management of Pre-eclampsia?
Management of pre-eclampsia involves treatment of maternal hypertension and close antenatal supervision of the mother and fetus with timely delivery to prevent deterioration of the mother and fetus
What are the maternal complications of Pre-eclampsia?
Eclampsia
HELLP syndrome
Pulmonary oedema
Cerebral haemorrhage
Cortical blindness
DIC
Renal failure
Hepatic rupture
Transient left ventricular systolic or diastolic dysfunction
What are the fetal complications of Pre-eclampsia?
Intrauterine growth restriction
Premature delivery
Abruptio placenta
Intrauterine fetal demise
Define Pre-eclampsia superimposed on Chronic HTN ?
Chronic hypertension with the development of any maternal organ dysfunction consistent with preeclampsia; thrombocytopenia, renal insufficiency, impaired liver function, pulmonary edema, cerebral or visual symptoms.
How is Pre-clampsia superimposed on C.HTN treated?
Same as Pre-eclampsia
What is Eclampsia?
Occurrence of one or more generalized Tonic-clonic seizures in a preeclamptic patient that cannot be attributed to any cause and no past history of seizure disorder.
What investigations are done in pre-eclamptic patients?
Urine dipstick
Full blood count: This may demonstrate a raised haematocrit/Hb (indicating haemoconcentration) and thrombocytopenia which could indicate HELLP syndrome - Hemolysis, Elevated Liver enzymes and Low Platelets.
Urea, creatinine and electrolytes: Uric acid is a particularly sensitive measure of pre-eclampsia and perinatal outcome, but it is only of clinical significance if the levels are increasing or are very high.
Liver function tests to exclude HELLP syndrome
Obstetric USS – EFW, AFI, Umbilical artery dopplers
Which parameter is used in Malawi in place of uric acid? And how is it interpreted?
- GFR
- Because of the increase in GFR during pregnancy, there is an increase in creatinine clearance lowering its levels to 0.9.So GFR greater than 0.9 indicates renal insuffiency.
Describe the findings on an obstetric USS.
EFW-estimated fetal weight which may be reduced due to reduced Uteroplacental circulation
AFI amniotic Fluid Index may be low because some of the amniotic fluid is produced from the Uteroplacental circulation which has been impaired
Umbilical artery Doppler’s shows reduced blood flow . Uteroplacental insufficiency results in increased resistance in the placenta which reduces blood flow in umbilical arteries
