Pre-eclampsia/Hypertension in pregnancy

Gestational HTN
1. new onset of HTN arising > 20wks & no additional features of pre-eclampsia
2. Resolves within 3 months postpartum
Pre-eclampsia
1. after 20 weeks gestation
2. New onset of hypertension +
  1. Proteinuria +
  2. end organ dysfunction +
  3. multisystem involvement of ≥1 other organ system +/- fetus
3. Resolves within 3 months postpartum
Chronic HTN = HTN confirmed preconception OR prior to K20 without a known cause
1. Hypertension confirmed prior to conception or prior to 20+0 weeks
2. May include women entering pregnancy on antihypertensive therapy with well controlled hypertension
3. Can be defined as:
  1. Essential hypertension (no secondary cause determined)
  2. Secondary hypertension where causes may include:
    1. Renal parenchymal disease (e.g. glomerulonephritis, reflux nephropathy and adult polycystic kidney disease)
    2. Renal artery stenosis
    3. Systemic disease with renal involvement (e.g. diabetes mellitus, systemic lupus erythematosus (SLE))
    4. Endocrine disorders (e.g. phaeochromocytoma, Cushing’s syndrome, primary hyperaldosteronism, hyper- or hypothyroidism and acromegaly)
    5. Coarctation of the aorta
    6. Obstructive sleep apnoea
    7. Medications or supplements (e.g. oral contraceptives, nonsteroidal
    8. anti-inflammatory drugs, corticosteroids, cocaine, stimulants,
    9. antipsychotic medications 11

Diagnosis criteria

A diagnosis of pre-eclampsia requires both
- Hypertension arising after 20+0 weeks gestation, confirmed on 2 or more occasions AND
- One or more of the organ/system features related to the mother and/or fetus identified below.
Note:
- Hypertension may not be the first manifestation
- Pre-existing hypertension is a strong risk factor for the development of pre-eclampsia 6 and requires close clinical surveillance
- Proteinuria is common but is not mandatory to make the clinical diagnosis

the organ/system features

Renal
- Random urine protein to creatinine ratio greater than or equal to 30 mg/mmol from an uncontaminated specimen (proteinuria)
- Serum or plasma creatinine greater than or equal to 90 micromol/L or Oliguria (less than 80 mL/4hours or 500 mL/24 hours)
Haematological
- Thrombocytopenia (platelets under 150 x 109/L)
- Haemolysis (schistocytes or red cell fragments on blood film, raised bilirubin, raised lactate dehydrogenase (LDH), decreased haptoglobin)
- Disseminated intravascular coagulation (DIC)
Liver
- New onset of raised transaminases (over 40 IU/L) with or without epigastric or right upper quadrant pain
Neurological
- Headache
- Persistent visual disturbances (photopsia, scotomata, cortical blindness, retinal vasospasm)
- Hyperreflexia with sustained clonus
- Convulsions (eclampsia)
- Stroke
Pulmonary oedema
Uteroplacental
- Fetal growth restriction (FGR
- Suspected fetal compromise
- Abnormal umbilical artery Doppler wave form analysis
- Stillbirth

Hypertension

Confirm non-severe hypertension by measuring BP over several hours
Up to 70% of women with an office BP of 140/90 mmHg have normal BP on subsequent measurements on the same visi

Proteinuria

Screen for proteinuria with urinary dipstick at first visit and at each subsequent visit
Quantify by laboratory methods if:
- Greater than or equal to 2+ proteinuria or
- Persistent 1+ proteinuria or
- Pre-eclampsia is suspected
In an uncontaminated sample, a urine protein to creatinine ratio greater than 30 mg/mmol is diagnostic of proteinuria in pregnancy
24 hour urine collection is not necessary in routine clinical management
Proteinuria testing does not need to be repeated once significant proteinuria in the setting of confirmed pre-eclampsia has been detected

baseline blood

Differentials
- First episode migraine
- Preeclampsia
- Benign / idiopathic intracranial hypertension

Symptoms of pre-eclampsia:
- generally asymptomatic and can only be detected by routine screening
- if present, the most frequent symptoms are
  - headache
  - visual disturbance (commonly ‘flashing lights’)
  - epigastric pain
  - vomiting
  - oedema (especially facial oedema) – these symptoms in conjunction with raised blood pressure should indicate immediate referral for obstetric review
- women may rarely present with a convulsion
  - if a first fit occurs in the second part of pregnancy with no other known cause this is a strong indication of pre-eclampsia
- intrauterine growth retardation

Examination
- excessive weight gain – more than 1.0 Kg per week
- ascites
- Vital signs – BP especially important!
- Neurological examination
  - Fundoscopy for papilloedema
  - Hyperreflexia in preeclampsia
  - Visual exam
- HELLP
  - Tender RUQ
- Heart / lungs
  - Severe preeclampsia can give pulmonary oedema
- Foetal
  - Fundal height – much lower than 30w suggests intrauterine growth retardation
  - Foetal HR for wellbeing
- Bedside investigations
  - Urine – proteinuria >3+ on two occasions >3 hours apart

Management of hypertension in preeclampsia
- Choices are labetalol, nifedipine or hydralazine
- Nifedipine only available in oral form and takes about an hour to work
- Hydralazine in acute setting, can have a first time episode of orthostatic hypotension so give with a bolus of fluids
- Can switch to nifedipine afterwards
- Indication is SBP >170 or DBP > 110

Management of eclampsia (seizures)
- timing of the delivery
- Management of any seizure
  - Left lateral position
  - Oxygen on
  - Terminate the seizure as per any seizure whilst magnesium is being drawn up eg midazolam 5mg IV
- Magnesium
  - 4g IV over 20 mins then 1g/h for 24 hours
  - Need to monitor for hypermagnsium = respiratory depression, CNS depression and bradycardia (especially after midazolam)

long-term health risks

	Future risks if gestational hypertension	Future risks if preeclampsia	Future risks if severe preeclampsia, HELLP syndrome or eclampsia
Gestational hypertension in future pregnancy	Risk ranges from about 1 in 6 (16%) to about 1 in 2 (53%).	Risk ranges from about 1 in 8 (13%) to about 1 in 2 (47%)
Preeclampsia in future pregnancy	Risk ranges from 1 in 50 (2%) to about 1 in 14 (7%)	Risk up to about 1 in 6 (16%). No additional risk if interval before next pregnancy < 10 years	If birth was needed before 34 weeks risk is about 1 in 4 (25%). If birth was needed before 28 weeks risk is about 1 in 2 (55%).
Cardiovascular disease	Increased risk of hypertension and its complications	Increased risk of hypertension and its complications	Increased risk of hypertension and its complications
End-stage kidney disease		If no proteinuria and no hypertension at 6-8 week postnatal review, relative risk increased but absolute risk low. No follow-up needed.
Thrombophilia		Routine screening not needed