Pregnancy complicated with hypertension

Definitions

Chronic hypertension is hypertension that is present at the booking visit or before 20 weeks or if the woman is already taking antihypertensive medication when referred to maternity services. It can be primary or secondary in aetiology.

Eclampsia is a convulsive condition associated with pre-eclampsia.

HELLP syndrome is haemolysis, elevated liver enzymes and low platelet count.

Gestational hypertension is new hypertension presenting after 20 weeks withoutsignificant proteinuria.

Pre-eclampsia is new hypertension presenting after 20 weeks with significant proteinuria.

Severe pre-eclampsia is pre-eclampsia with severe hypertension and/or with symptoms,and/or biochemical and/or haematological impairment.

Significant proteinuria is defined in recommendation

Severity of hypertension

Mild hypertension diastolic blood pressure 90–99 mmHg, systolic blood pressure  140–149 mmHg.

Moderate hypertension diastolic blood pressure 100–109 mmHg, systolic blood pressure150–159 mmHg.

Severe hypertension diastolic blood pressure 110 mmHg or greater, systolic blood pressure 160 mmHg or greater

Etiology

Normal implantation , uterine spiral arteries undergo extensive remodeling as they are invaded by endovascular trophoblasts

Incomplete invasion (decidual vessels , not myometrial vessels) causes preeclampsia

Pathophysiology

CNS

Thrombosis of arterioles, microinfarcts, and petechial hemorrhage

Cerebral edema: increased intracranial pressure

EEG: nonspecific abnormality (75% in eclamptic patient)

Eyes

Serous retinal detachment

Cortical blindness

Pulmonary system

Pulmonary edema

Aspiration of gastric contents: the most dreaded complications of eclamptic seizures

Kidneys

Glomeruloendotheliosis and Swelling of the glomerular capillary endothelium

Decreased GFR

Proteinuria

Increase of plasma uric acid, creatinine,

Liver

The spectrum of liver disease in preeclampsia is broad

Subclinical involvement

Rupture of the liver or hepatic infarction

HELLP syndrome: hemolysis, elevated liver enzymes and low platelets

CVS

Generalized vasoconstriction, low-output, high-resistance state

Untreated preeclamptic women are significantly volume-depleted

Capillary leak

Cardiac ischemia, hemorrhage, infarction, heart failure

Blood

Volume: reduced plasma volume

Normal physiologic volume expansion does not occur

Generalized vasoconstriction and capillary leak

Hematocrit

Coagulation

Isolated thrombocytopenia: <150,000/ml

Microangiopathic hemolytic anemia

DIC (5%)

HELLP syndrome: in severe preeclampsia

    schistocytes on the peripheral blood smear

    lactic dehydrogenase > 600 u/L

    total bilirubin > 1.2 mg/dl

    aspartate aminotransferase >70 U/L

    platelet count <100,000/mm3

      

Placenta

Acute atherosis of spiral arteries: fibrinoid necrosis of the arterial wall, the presence of lipid and lipophages and a mononuclear cell infiltrate around the damaged vessel----vessel obliteration---- placental infarction

IUGR or stillbirth

Placental abruption

Chronic hypertension

Three types

1. Essential HT

Essential hypertension is defined by a blood pressure greater than or equal to 140mmHg systolic and/or 90mmHg diastolic confirmed before pregnancy or before 20 completed weeks gestation without a known cause.

2. White coat HT

3. Secondary HT

Important secondary causes of chronic hypertension in pregnancy include:

·        Chronic kidney disease e.g. glomerulonephritis, reflux nephropathy, and adult                                                            polycystic kidney disease.

·        Renal artery stenosis

·        Systemic disease with renal involvement e.g. diabetes mellitus, systemic lupus                                                                                     erythaematosus.

·        Endocrine disorders e.g. phaeochromocytoma, Cushing’s syndrome and primary

·        hyperaldosteronism.

·        Coarctation of the aorta.

Gestational Hypertension

Gestational hypertension is characterised by the new onset of hypertension after 20 weeks gestation without any maternal or fetal features of preeclampsia, followed by return of blood pressure to normal within 3 months post-partum.

The earlier the gestation at presentation and the more severe the hypertension, the higher is the likelihood that the woman with gestational hypertension will progress to develop preeclampsia or an adverse pregnancy outcome.

Preeclamsia

Preeclampsia is a multi-system disorder unique to human pregnancy characterized by hypertension and involvement of one or more other organ systems and/or the fetus. 

Raised blood pressure is commonly but not always the first manifestation.

Proteinuria is the most commonly recognized additional feature after hypertension but should not be considered mandatory to make the clinical diagnosis.

A diagnosis of preeclampsia can be made when hypertension arises after 20 weeks gestation and is accompanied by one or more of the following signs of organ involvement:

Renal involvement

Significant proteinuria – a spot urine protein/creatinine ratio ≥ 30mg/mmol Serum or plasma creatinine > 90 μmol/L

Oliguria: <80mL/4 hr

Haematological involvement

Thrombocytopenia <100,000 /µL

Haemolysis: schistocytes or red cell fragments on blood film, raised bilirubin, raised lactate dehydrogenase >600mIU/L, decreased haptoglobin

Disseminated intravascular coagulation

Liver involvement

Raised serum transaminases

Severe epigastric and/or right upper quadrant pain.

Neurological involvement

Convulsions (eclampsia)

Hypereflexia with sustained clonus

Persistent, new headache

Persistent visual disturbances (photopsia, scotomata, cortical blindness, posterior reversible encephalopathy syndrome, retinal vasospasm)

Stroke

Pulmonary oedema

Fetal growth restriction (FGR)

Preeclampsia superimposed on chronic hypertension

Superimposed preeclampsia

Pre-existing hypertension is a strong risk factor for the development of preeclampsia.

Superimposed preeclampsia is diagnosed when a woman with chronic hypertension develops one or more of the systemic features of preeclampsia after 20 weeks gestation.

Symptoms of preeclamsia  (impending symptoms):

·        severe headache

·        problems with vision, such as blurring or flashing before the eyes

·        severe pain just below the ribs

·        vomiting

·        sudden swelling of the face, hands or feet

Risk factors and prevention of gestatinal hypertension and preeclamsia

Advise women at high risk of pre-eclampsia to take 75 mg of aspirin daily from

12 weeks until the birth of the baby.

Women at high risk are those with any of the following:

·        hypertensive disease during a previous pregnancy

·        chronic kidney disease

·        autoimmune disease such as systemic lupus erythematosis or antiphospholipid

·        syndrome

·        type 1 or type 2 diabetes

·        chronic hypertension.

Advise women with more than one moderate risk factor for pre-eclampsia to

take 75 mg of aspirin daily from 12 weeks until the birth of the baby.

Factors indicating moderate risk are:

·        first pregnancy

·        age 40 years or older

·        pregnancy interval of more than 10 years

·        body mass index (BMI) of 35 kg/m2

·        or more at first visit

·        family history of pre-eclampsia

·        multiple pregnancy.

Evaluation of Hypertension in Pregnancy

History

Identification  and Complaint

Impending symptoms

FM /abdominal pain/PV bleeding

Past Medical Hx, Past Family Hx

Past Obstetrical Hx, Past Gyne Hx

Social Hx

Medications, Allergies

Prenatal serology, blood work

Assess for Hypertension in Pregnancy risk factors

Physical

Vitals

Edema

Vision

Cardiovascular

Respiratory

Abdominal  = Epigastric pain, RUQ pain

Neuromuscular and Extremities = Reflex, Clonus

Fetus = Leopold’s, FHB

Investigation for gestational hypertension

Any woman presenting with new hypertension after 20 weeks gestation should be assessed for signs and symptoms of preeclampsia.

Initially, assessment and management in a day assessment unit may be appropriate.

If features of preeclampsia are detected, admission to hospital is indicated. The presence of severe hypertension, headache, epigastric pain, oliguria or nausea and vomiting are ominous signs which should lead to urgent admission and management, as should any concern about fetal wellbeing.

The following investigations should be performed in all women with new onset hypertension after 20 weeks gestation:

1.     Spot urine albumin

2.     Full blood count

3.     Creatinine, electrolytes, urate

4.     Liver function tests

5.     Ultrasound assessment of fetal growth, amniotic fluid volume and umbilical artery Doppler assessment.

Management of chronic hyper tension

In pregnant women with uncomplicated chronic hypertension aim to keep

blood pressure lower than 150/100 mmHg.

Do not offer pregnant women with uncomplicated chronic hypertension

treatment to lower diastolic blood pressure below 80 mmHg.

Offer pregnant women with target-organ damage secondary to chronic

hypertension (for example, kidney disease) treatment with the aim of keeping

blood pressure lower than 140/90 mmHg.

Management of  gestational hypertension

Preeclampsia is a progressive disorder that will inevitably worsen if pregnancy continues.

Current therapy does not ameliorate the placental pathology nor alter the pathophysiology or natural history of preeclampsia.

 Delivery is the definitive management and is followed by resolution, generally over a few days but sometimes much longer.

Timing of birth in gestational HT

Do not offer birth before 37 weeks to women with gestational hypertensionwhose blood pressure is lower than 160/110 mmHg, with or without antihypertensive treatment.

For women with gestational hypertension whose blood pressure is lower than

160/110 mmHg after 37 weeks, with or without antihypertensive treatment,

timing of birth, and maternal and fetal indications for birth should be agreed

between the woman and the senior obstetrician.

Offer birth to women with refractory severe gestational hypertension after a

course of corticosteroids (if required) has been completed.

Timing of delivery in  preeclamsia

Manage pregnancy in women with pre-eclampsia conservatively (that is, do not

plan same-day delivery of the baby) until 34 weeks.

Offer birth to women with pre-eclampsia before 34 weeks, after discussion with

neonatal and anaesthetic teams and a course of corticosteroids has been

given if:

·        severe hypertension develops refractory to treatment

·        maternal or fetal indications develop as specified in the consultant plan

Offer birth to women who have pre-eclampsia with mild or moderate

hypertension at 34+0 to 36+6 weeks depending on maternal and fetal condition,

risk factors and availability of neonatal intensive care.

Control of HT

Labetalol is the 1^st line drug , but its expensive and availability is restricted in Sri Lanka .

Table 1 Drugs which can be used to control blood pressure during pregnancy

Drugs	Dose	Action	Contraindication	Practice points
Methyl Dopa	250- 1000mg tds	Central	Depression	Slow onset of action over 24 hours, dry mouth, sedation, depression, blurred vision Withdrawal effects: rebound hypertension
Labetalol	100- 400mg qds	Blocker with mild alpha vasodilator effect	Asthma, chronic airways limitation	Bradycardia, bronchospasm, headache, nausea, scalp tingling (labetalol only) which usually resolves within 24 hours
Nifedipine	20-60mg bd	Ca channel antagonist	Aortic stenosis	Severe headache in first 24 hours Flushing, tachycardia, peripheral oedema, constipation
Prazosin	0.5-5 mg qds	Alpha blocker		Orthostatic hypotension especially after first dose
Hydralazine	25-50 mg qds	Vasodilators		Flushing, headache, nausea, lupus-like syndrome

Table 2.Drugs used to control severe HT

	Dose	Route	Onset of action	Adverse effect
Labetalol	20 -80mg Max 80mg	IV bolus over 2 min, Repeat every 10 mins prn	Maximal effect usually occurs within 5 minutes after each dose	Bradycardia: Hypotension Fetal Bradycardia
Nifedipine	10-20MG tablet Max 40mg	Oral	30-45 minutes Repeat after 45 minutes	Headache Flushing
Hydralazine	10mg (First dose 5mg if fetal compromise]) Max 30mg	IV bolus, repeat every 20mins	20 min	Flushing Headache Nausea Hypotension Tachycardia
Diazoxide	15-45mg Max 300mg	IV rapid bolus	3-5 mins, repeat after 5 mins	Flushing Warmth along Injection site Hypotension

Eclamsia

Preeclampsia complicated by generalized tonic-clonic convulsions

Appear before , during , or after labor

Most common in last trimester

1/3 of eclamsia occur in the postpartum.

Usually begin in facial twitch , entire body rigid , generalized muscle contraction , jaw open & close violently

Major complications

Cerebrovascular hemorrhage

placental abruption 

 aspiration pneumonia

 pulm edema

arrest

 ARF

death

Pathophysiology

Pulmonary edema from aspiration pneumonitis or heart failure

Death from massive cerebral hemorrhage

Hemiplegia from sublethal hemorrhage

Blindness from retinal detachment or occipital lobe ischemia & edema

Persistent coma due to uncal herniation

Rarely eclampsia followed by psychosis

Diferential diagnosis

epilepsy

encephalitis

meningitis

cerebral tumor

cysticercosis

ruptured cerebral aneurysm

management

A,B,C  management

Control BP

Control fits

Delivery of the baby                

Controlling fits

Mgso4 is the 1^st line drug

Dose 4g IV over 20min followed by infusion of 1g /h.

Continue infusion for 24 h from delivery or from last fits .

Effective anticonvulsant without producing CNS depression in either mother or infant .Not given to treat HT

Monitor for mg toxicity

Toxicity:

·        Diminished or loss of patellar reflex

·        Diminished respiration

·        Muscle paralysis

·        Blurred speech

·        Cardiac arrest

Reversal of toxicity

Reversal of toxicity:

Slow i.v . 10% calcium gloconate

Oxygen supplementation

Cardiorespiratory support