This document discusses hypertension in pregnancy. It covers how to measure blood pressure in pregnant women, the diagnostic criteria for gestational hypertension and preeclampsia, risk factors, pathophysiology, tests to run, management including medications and delivery timing, and postpartum care. Preeclampsia is a leading cause of maternal and infant morbidity and mortality whose exact causes remain unknown but may be related to placental dysfunction and an exaggerated maternal inflammatory response.

1. Hypertension in Pregnancy

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
 Tests for proteinuria
 Risk factors for pre-eclampsia
 Pathophysiology of pre eclampsia
 How to manage the hypertensive gravida
 Which is the best drug to lower BP

3. This talk(2)
 Who should be delivered? How & Where
 Best practice intrapartum care
 Who requires an anticonvulsant?
 What is the best drug for Eclampsia?
 Best practice postpartum care
 Best practice anaesthetic care
 Prognosis after pre-eclampsia
 Can pre-eclampsia be predicted?
 Can pre-eclampsia be prevented?

4. How to Measure BP in a Pregnant Woman
o Automated machines not recommended
o Unless calibrated against a mercury sphygmomanometer in
the individual patient
 Appropriate sized cuff
 Seated for 2 - 3 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
 Not in itself diagnostic – look for other problems
 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 (>300 mg in 24 hours or P:C > 0.30)
 S Creat >90
 Oliguria
 Hepatic
 Elevated transaminases (AST or ALT >70)
 Epigastric or RUQ pain
 Haematological
 Thrombocytopenia (<100)
 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” and some method of
assessment is critical to good obstetric care
 Evidence for other organ involvement in Pre
eclampsia is a mix of symptoms, signs and tests

9. Tests of Proteinuria
 The screening test is by dipstick
 Have a sensitivity >90% using ≥ 1+
 But correlate poorly with high protein loss
 And false negative rates up to 20%
 Will miss >300 mg/24 hours in up to 1:8 patients
 And the test strips spoil quickly in humidity
 Boiling urine is sensitive and quantifiable
 But messy and disliked by midwives
 24 hour collection and quantification by lab
 Is the gold standard
 But labour intensive and slow
 The protein:creatinine ratio on a spot sample is a
good compromise

10. Proteinuria in Practice
 Significant proteinuria occurs when...
 There is ≥ 2+ on dipstick
 Trace or 1+ should be regarded as equivocal
 The 24 hour urine collection is > 300 mg
 The spot urine protein:creatinine ratio is ≥
30 mg/mmol
 There is > “cloud” on boiled urine
 When significant proteinuria has been
detected there is little point in repeating
the measure

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

12. 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 is very
bad
 Monitoring for superimposed pre eclampsia can
be difficult if there is chronic proteinuria
 Donors of a kidney have 2.4-fold increased risk
of PE but usually not severe

13. 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

14.  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
Pathophysiology of Pre eclampsia

15.  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
Pathophysiology of Pre eclampsia

16.  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
Pathophysiology WHY?

17.  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
Pathophysiology WHAT?

18.  Hypertension/ Proteinuria/ oedema
 Low platelets Consumption
 Raised urate Cell (DNA) death
 Raised Haematocrit Reduced plasma volume
 Haemolysis
 Abnormal LFT’s
 Abnormal clotting Widespread DIC
Pathophysiology WHAT?

19. 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 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 AFI
and UA Dopplers

20. Frequency of Testing

21. 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
controversial
 Delivery will cure pre eclampsia & gestational
hypertension
 Remember thromboprophylaxis

22. Tests of Fetal Welfare

23. Which Drug is Best for
Hypertension in Pregnancy?
 The drug that you know best
 Aldomet
 Up to 2250 mg per day
 Labetalol
 Up to 1200 mg/day
 Oxyprenalol
 Up to 480 mg/day
 Nifedipine
 Up to 120 mg/day
 Prazosin
 Up to 15 mg/day

24. 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 130 -150 systolic and 80 –
100 diastolic

25. Which Drug is Best for Acute
Hypertension?
 The drug that you know best
 IV Hydralazine 5 – 10 mg every 20-30 min
 or by infusion
 IV Labetalol 20 – 50 mg over 2 min.
 Repeat after 15 – 30 min
 Nifedipine crushed oral 10 mg
 Repeat after 30 min
 IV Diazoxide 15 – 45 mg bolus
 Repeat after 5 min to a maximum of 300 mg

26. 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 4G over 10 – 15 min
 Then 1 -2 G/hour by infusion
 If seizure recurs then give another 2 – 4 G
bolus
 IV Diazepam only for status eclampticus
 Monitor urine output, respirations, O2
saturation and DTJ’s

27. Who Needs Fluid Expansion?
 If there is severe proteinuria and oliguria
 Then give 500 – 1000 ml cautiously
 Injudicious use carries a risk of pulmonary oedema and
adult RDS
 Pre load prior to epidural or spinal
 Consult with anaesthetist
 Use colloids rather than crystalloids
 Sometimes required if BP drops suddenly
 Sometimes occurs with Diazoxide/Hydralazine
 CTG monitoring desirable
 Abruption requires prompt resuscitation
 Often requires blood
 Watch urine output and/or JVP

28. Who Requires Delivery?
 Pre eclampsia >36 completed weeks
 Uncontrollable hypertension
 Deteriorating renal, hepatic or haematologic
state
 For GA >32w and good neonatal facilities
delay only long enough to give steroids
 Eclampsia or imminently eclamptic
 Fetus is compromised
 APH - abruption

29. Induction of Labour vs Expectant Management for
Gestational Hypertension Koopmans et al Lancet 2009
 The HYPITAT study
 A multicentre RCT of 756 women in Netherlands
 Were 36 – 41 weeks with a diagnosis of mild pre
eclampsia or gestational hypertension
 Of the women randomised to induction of labour
31% had a poor outcome vs 44% for observation
(RR=0.71, CI 0.59-0.86, p<0.001)
 Poor outcomes included eclampsia, HELLP, severe
pre eclampsia and PPH
 No greater risk of Caesarean or neonatal morbidity
 Active management is also more cost effective

30. 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

31. 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
 SVD is not a sin!

32. Anaesthetic Implications
 Epidural good for both vaginal & abdominal
delivery
 Spinal + Vasopressin also okay
 Spinal plus epidural for a few cases
 Low dose aspirin okay for epidural
 GA for acute fetal compromise or low
platelets
 <50, and 50 – 75 is a grey zone
 Watch for hypertension during GA intubation
 Use antacid and lateral tilt
 Cautious use of oxytocin boluses

33. 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
 Use Nifedipine PRN
 OK to discharge 3d after BP control
 Follow up weekly to 6w then 3m

34. 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 50-
66% recurrence risk
 Most recover by 12w but these patients are at
increased lifetime risk of hypertension and
related disease

35. Can Preeclampsia be predicted
and prevented?
 Identifying the patient at risk
 Early pregnancy testing
 Prevention strategies
 Especially the role of low dose aspirin

36. 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

37. Patients at risk

38. Prediction of Pre eclampsia
 Risk factors alone are insensitive and non
specific
 Response to an infusion of angiotensin
 Suitable only in a research setting
 Measure vasoactive proteins in serum
 PAPP-A, Placental growth factor (PlGF)
 Doppler studies at 12 – 14w
 Placental resistance & Uterine artery pulsatility
 Together these last two can identify 90% of
women who will get PE before 34w
 With false positive rate of 10%

39. The prevention of pre eclampsia
with low dose Aspirin – WHO?
 History of fetal death or severe IUGR
 Patients who previously required delivery
for pre eclampsia prior to 34w
 Conditions with high risk of pre eclampsia
eg Lupus or homozygous for thrombophilia
 These patients also require heparin
 Patients identified by Screening at 12 –
14w (London FMF program)
 Also use Ca supplements of 1.5G daily

40. The prevention of pre eclampsia
with low dose Aspirin - Results
 Meta analysis suggests that 100 – 150 mg
daily started BEFORE 16 w
 Reduces risk of early onset pre-eclampsia by 50 –
90%
 Less valuable if started after 16w
 You need to treat 4-5 women to prevent one FDIU
or severe IUGR
 RISKS
 Does not increase the risk of APH, PPH or fetal
intracranial haemoorhage
 It is also not teratogenic

41. Other measures to prevent
preeclampsia
 Anti oxidant supplements (Vitamins C, E)
 Increase the risk of stillbirth and IUGR. Trials stopped
 Folic acid and multivitamins
 Requires more RCTs
 Metformin
 Improves uteroplacental circulation and reduces the rate
of pre eclampsia and pre term birth for PCO patients who
take it in early pregnancy. Needs study in a wider group of
patients
 Abdominal decompression
 Unproven and abandonded

42. For the NICE Guideline go
to
http://pathways.nice.org.uk/pathways/hyperten
sion-in-pregnancy

43. Any Questions or
Comments?
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