1. Hypertension in Pregnancy for Undergraduates
Max Brinsmead MB BS PhD
February 2015

2. This talk How to measure BP When is a pregnant woman hypertensive
What is the Differential Diagnosis
What tests are required and how do you interpret them
Risk factors for pre-eclampsia
Pathophysiology of pre eclampsia
How to manage the hypertensive gravida
Drugs to lower BP in pregnancy

3. This talk(2) When to deliver Best practice intrapartum care
Who requires an anticonvulsant?
What is the best drug for Eclampsia?
Best practice postpartum care
Prognosis after pre-eclampsia
Can pre-eclampsia be prevented?

4. How to Measure BP in a Pregnant Woman
Automated machines not recommended
Unless calibrated against a mercury sphygmomanometer in the individual patient
Appropriate sized cuff
Seated for minutes with feet supported
Both arms first visit
Palpate systolic and go 20 mm higher
Deflate slowly 2 mm every sec
Use Korotkoff 5 (or 4 if 5 absent) for diastolic
Repeated measures may be required
Ambulatory monitoring useful for White Coat Hypertension

5. When is a Pregnant Woman Hypertensive?
>140/90 on >one occasion
(Rise of >30 systolic or >15 diastolic)
Knowledge of prior BP very important
No longer accepted as a diagnostic point
Severe hypertension is >169 systolic and or diastolic >109
Requires admission and urgent Rx
(However, the diagnosis is more important than the actual level of BP).

6. Differential Diagnosis of Hypertension in Pregnancy
Gestational Hypertension
Sustained hypertension after 20w of pregnancy without any other organ involvement. Returns to normal in 3m
Preeclampsia
Sustained hypertension after 20w of pregnancy with evidence of other organ involvement. Returns to normal in 3m
Chronic Hypertension
Hypertensive before 20w. 95% is Essential Hypertension Includes “White Coat Hypertension”

7. Systems involved in Preeclampsia
Renal
Significant proteinuria
S Creat >90
Oliguria
Hepatic
Elevated transaminases
Epigastric or RUQ pain
Haematological
Thrombocytopenia
Haemolysis
DIC
CNS
Eclampsia or stroke
Hyperreflexia with sustained clonus
Severe headache or visual disturbance
Cardiovascular
Pulmonary oedema
Placental
IUGR
Abruption

8. Please note
I have not used the words “Pregnancy induced Hypertension” or PIH
No mention is made of oedema
Proteinuria is the most common manifestation of “other system involvement”
Evidence for other organ involvement in Pre eclampsia is a mix of symptoms, signs and tests

9. Some rare causes of preeclampsia before 20w
Hydatidiform mole
Fetal triploidy (with or without partial mole)
Severe renal disease
Lupus obstetric syndrome

10. Renal Disease in Pregnancy
Responsible for about 5% of chronic hypertension
Causes include:
chronic or recurrent infection
glomerulonephritis
renal artery stenosis
Must be assessed by creatinine clearance (CC) which doubles in normal pregnancy
When CC falls below 50% the prognosis for a pregnancy is very bad
Monitoring for superimposed pre eclampsia can be difficult if there is chronic proteinuria

11. Some rare causes of hypertension
Coarctation of the aorta
Sometimes the clue is to measure BP in both arms
There is a systolic murmur that can be heard in the back
Phaeochromocytoma
Paroxysms of symptomatic hypertension
The clue to diagnosis is to think of it
Associated with high levels of catecholamines
Hyperaldosteronism
Also known as Conn’s disease

12. Pathophysiology of Pre eclampsia
Placental tissue
In healthy pregnancies cytotrophoblast infiltrates the decidual portion of the uterine spiral arteries
In order to increase maternal blood flow to the placenta
In patients destined to develop pre eclampsia this fails to occur
This results in placental hypoperfusion
These changes occur at <16 weeks gestation but the pre eclampsia may not be manifest until much later in the pregnancy

13. Pathophysiology of Pre eclampsia
Hypoperfusion of the Placenta
Becomes worse as pregnancy progresses
The abnormal uterine vasculature is unable to accommodate the normal rise in blood flow to the fetus/placenta that occurs with increasing gestational age.
Late placental changes consistent with ischemia include atherosis (lipid-laden cells in the wall arterioles), fibrinoid necrosis, thrombosis, sclerotic narrowing of arterioles, and placental infarction

14. Pathophysiology WHY? An ‘immunolgical’ response to pregnancy
---in ‘at risk’ or predisposed women
A response to a conceptus whose genetic material is 50% foreign (from the father)
A failure of ‘Blocking Antibody’
This disease is still a mystery

15. Pathophysiology WHAT? Contracted intravascular volume of mother
In reality a failure to increase plasma volume
↑Sensitivity to pressure agents
Leaky capillaries
Reduced oncotic pressure
In part due to low serum albumen
Poor placental reserve
A fetus at risk of hypoxia and death

16. Tests for the Hypertensive Gravida
Blood tests
FBC - look at HB, Haematocrit and Platelets
UEC - look at Creatinine Should be < 0.07 (or 70)
URATE - equivalent to weeks of gestation
Liver enzymes – AST & ALT should be <70. Ignore ALP
Urine Tests
UMCS - exclude UTI and look for casts
Protein:Creatinine ratio from spot test (>30 significant)
24 hr protein excretion (>300 mg/day significant)
Assess fetal welfare by CTG & Scan for amniotic fluid volume & umbilical artery Dopplers

17. Management of Hypertensive Gravida
Hospitalise if pre-eclamptic
Discharge if “just BP”
Bed rest only when there is proteinuria
Control BP to protect mother from severe hypertension
Role of antihypertensive agents for mild & moderate chronic hypertension is still controversial
Delivery will cure pre eclampsia and gestational hypertension
Remember thromboprophylaxis

18. Drugs for Hypertension in Pregnancy?
Aldomet
An old and safe drug
Beta Blockers
Labetalol widely used in Australia
Oxyprenalol also shown in RCT to be useful
Ca channel blockers
Nifedipine
Prazosin
Relaxes pressor arterioles

19. Drugs for Hypertension in Pregnancy?
Combination therapy of drugs from different classes is possible e.g.
Aldomet + Beta blocker + Prazosin
Do not use…
Thiazide diuretics – reduce plasma volume
Highly selective beta blokers – cause IUGR
ACE inhibitors – may cause IUFD
Aim for BP systolic and 80 – 100 diastolic

20. Drugs for Acute Hypertension in Pregnancy
IV Hydralazine
IV Labetalol
Not available in Australia
Nifedipine tablets crushed and oral
Repeat after 30 min
IV Diazoxide in small boluses

21. Which Drug is Best for Eclampsia?
First aid is more important than drugs
Protect from injury
Secure an airway
Administer oxygen
Then secure IV access
IV MgSO4 loading dose
Maintain by infusion
IV Diazepam only for status eclampticus
Monitor urine output, respirations, O2 saturation and deep tendon jerks

22. Who Requires Delivery? Pre eclampsia >36 completed weeks
Uncontrollable hypertension
Deteriorating renal, hepatic or haematologic state
Eclampsia or imminently eclamptic
Fetus is compromised
Give steroids to mature the fetal lungs
APH - abruption

23. How to Deliver Deliver vaginally if >37w and Cx is favourable
or can be ripened
Caesarean only if the above not met
Elective CS usually at gestations <35w
Inappropriate attempts at delivery when it is not indicated is an invitation to CS (and more CS)
Deliver in an environment that can cope with a severe multisystem disease
Don’t overlook patient’s and family’s psychological needs

24. Intrapartum Care
Assess convulsive risk and consider prophylactic MgSO4
Control BP with an epidural or IV Hydralazine
Careful fluid balance
Monitor the fetus
Avoid ergometrine

25. Postpartum Care Things may get worse before they get better
Oliguria for 24 hours is common
Seizure risk is greatest for 48 hrs
Continue MgSO4 infusion for 24 hrs
Avoid NSAIDs
Treat any BP >150/100
OK to discharge 3 days after BP control
Follow up weekly to 6w then 3m

26. The Prognosis after Pre eclampsia
Mild pre eclampsia near term has a low recurrence risk
Unless there is a new partner or a long gap to the next pregnancy
Severe pre eclampsia prior to 34w has a % recurrence risk
Most recover by 12w but these patients are at increased lifetime risk of hypertension and related disease

27. Risk factors for severe pre eclampsia
Previous pre eclampsia at <35w
Renal disease
Thombophilias
Autoimmune disease e.g. SLE
Diabetes
Multiple pregnancy
Severe alloimmunisation
Family history of pre eclampsia
Obesity
Increasing maternal age

28. The prevention of pre eclampsia with low dose Aspirin
History of fetal death or severe IUGR
Patients who required delivery for pre eclampsia prior to 34w
You need to treat 4-5 to prevent one FDIU or severe IUGR
Does not increase the risk of APH or PPH
Conditions with high risk of pre eclampsia eg Lupus or homozygous for thrombophilia
These patients also require heparin
Also give Ca supplements 1.5 G/day

29. For the NICE Guideline go to

30. Any Questions or Comments?
Please leave a note on the Welcome Page to this website