complications of preeclampsia & chronic hypertension

Hypertensive disorders of pregnancy: د.ناديه مضر الحلي
Complication of severe pre-eclampsia are:
• Eclampsia
• HELLP syndrome
• Pulmonary oedema
• Acute renal failure
• Placental abruption
• Intrauterine growth restriction (IUGR)
• Intrauterine fetal death

Eclampsia:
defined as new-onset tonic-clonic seizure in an otherwise healthy woman with hypertensive disorder of pregnancy, is a significant complication of preeclampsia and is associated with high maternal and neonatal morbidity and mortality.
Of seizures 44% occur postnatally, 38% antepartum & 18% intrapartum. The pathophysiology is thought to involve cerebral vasospasm leading to ischaemia & cerebral oedema.

Diagnosis:
Eclamptic seizures classically occur in the second half of pregnancy & up to 10 days postpartum. They are tonic-clonic followed by a brief period of coma. Many women manifest excitability or hyper-reflexia prior to the onset of seizure. The diagnosis of eclampsia is straight forward if the woman had PE, some have not established proteinuria & hypertension before the first fit.

Management:
• General measures:
? Do not leave the patient alone
? Call for help
? Inform consultant
? Prevent maternal injury during convulsion
• Air way: assess, maintain patency, protect air way, apply oxygen.
• Breathing: assess & ventilate as required.
• Circulation: evaluate pulse rate & BP, if absent initiate cardiopulmonary resuscitation (CPR) & call for help.
• Secure intravenous access as soon as possible
• Urinary catheter to assess urinary out put
• Fluid input/output chart

Most convulsions are self-limiting but anticonvulsant therapy is indicated to prevent recurrent seizures. Magnesium sulphate is the treatment of choice. It acts as membrane stabilizer & vasodilator & reduces intracerebral ischaemia. 4 g should be given i.v. slowly followed by i.v. infusion or i.m. regimen. Other anticonvulsant therapy include diazepam & phenytoin but are less effective. Maintenance infusion should continue for 24 h after the last fit or after delivery. Patient should be monitored for signs of magnesium toxicity, the first of which is loss of deep tendon reflexes, followed by respiratory depression & in severe cases cardiac standstill. So, the patient should be monitored hourly by patellar reflex, respiratory rate & oxygen saturation.
BP should be controlled using intravenous hydralazin or labetolol given in boluses or by continuous infusion, the aim is to keep diastolic BP between 95-105 mmHg. Delivery is indicated, vaginally if the patient is in advanced labour otherwise caesarean section.
Postpartum care: As a third of eclamptic fits occur postpartum, intensive monitoring is required, usually for 48 h after delivery. BP monitoring should continue & the patient should be reviewed at 6-12 weeks postpartum with liver & renal function test done for any residual disease.


HELLP Syndrome: the association of haemolysis (H) elevated liver enzymes (EL) & low platelet count ( LP). DIC with low fibrinogen may coexist. The commonest presenting symptom is epigastric or right upper quadrant pain. Severe pain with tender hepatomegaly may suggest subcapsular haematoma of the liver. The perinatal mortality is high. Maternal complications include placental abruption, acute renal failure, pulmonary oedema, pleural effusion & death. Delivery is the treatment of choice, corticosteroids may improve maternal laboratory indices.

Pulmonary oedema & acute renal failure: these complications occur in about 1-2% of cases of severe PE. Treatment of pulmonary oedema is with intravenous frusemide & oxygen. Patients with acute renal failure may need dialysis.

Chronic Hypertension:
CHT is present in 2-4 % of pregnant women. Over 90% of cases are due to essential hypertension & these women tend to be older, heavier & have a family history of hypertension. Other causes of chronic hypertension ( secondary) include:
• Chronic renal disease
• Renal artery stenosis
• Coarctation of the aorta
• Collagen vascular disease
• Pheochromocytoma
• Cushing s syndrome
• Conn s syndrome

Assessment including evaluation of the cardiovascular system & renal involvement & councelling are best done prior to conception. High-risk characteristics in women with CHT include:
• Maternal age >40 years
• Duration of hypertension > 15 years
• BP ?160/110 mmHg
• Diabetes
• Renal disease
• Cardiomyopathy
• Connective tissue disease
• Coarctation of the aorta
• Previous pregnancy with perinatal loss



Preconception assessment & councelling:
Advise should be given regarding anti-hypertensive therapy & life style modification. High body mass index BMI is associated with increased BP & weight loss may reduce BP. The type of antihypertensive taken should be considered. It is recommended that both diuretics & ACE inhibitors are changed to alternative anti-hypertensive agent.
Physical examination should include assessment of the body mass index, looking for signs suggestive of secondary hypertension like bruit in the renal artery, delayed femoral pulse, palpable polycystic kidney. Fundoscopy should be done to look for evidence of hypertensive retinopathy.
Investigations should include renal function test, urinalysis, 24 h urine collection for protein excretion & creatinine clearance, CXR, ECG & echocardiography especially for those with long history of CHT.
During pregnancy most women with CHT experience a fall in BP in the 1st half & may be normotensive at booking.
Complications of CHT:
Superimposed PE can complicate such patients, a rising plasma uric acid precede the development of proteinuria. Doppler studies of the uterine arteries at 20-24 weeks can predict women at risk of PE. Abruptio placentae is another complication. Perinatal mortality is related to the development of superimposed PE. It is not increased in uncomplicated CHT.

Antihypertensive therapy:
None of the commonly used antihypertensive therapy are known to be teratogenic. The antihypertensive therapy reduces the risk of severe hypertension but does not reduce the risk of superimposed PE, preterm delivery or perinatal death. Treatment is necessary when hypertension is severe & in high-risk patients where there is target organ damage. Methyldopa remains the drug of choice. If this fails to control BP nifedipine may be added. Beta-blockers may cause intrauterine growth restriction & better to be avoided. Angiotensin-converting enzyme inhibitors should be avoided because of the report of fetal death & neonatal renal failure.