Preeclampsia

Introduction

Preeclampsia is a complex hypertensive disorder of pregnancy characterized by the onset of high blood pressure and often a significant amount of protein in the urine. This condition typically occurs after 20 weeks of gestation in women whose blood pressure had previously been normal. Preeclampsia can lead to serious, even fatal, complications for both the mother and the baby if left untreated. It is a leading cause of maternal and perinatal morbidity and mortality worldwide.

Epidemiology

Preeclampsia affects approximately 5-8% of all pregnancies globally. The incidence varies widely depending on geographic location, socioeconomic status, and access to prenatal care. It is more common in first pregnancies, in women with a history of chronic hypertension, and in those with a family history of the condition. Other risk factors include obesity, diabetes, and multiple gestations.

Pathophysiology

The exact pathophysiology of preeclampsia remains unclear, but it is believed to involve abnormal placentation, endothelial dysfunction, and an exaggerated inflammatory response. During normal pregnancy, the trophoblast cells invade the maternal spiral arteries, transforming them into high-capacity, low-resistance vessels. In preeclampsia, this process is defective, leading to reduced placental perfusion and ischemia. This placental ischemia is thought to release factors into the maternal circulation that cause widespread endothelial dysfunction, resulting in hypertension and proteinuria.

Clinical Features

The hallmark of preeclampsia is the new onset of hypertension and proteinuria after 20 weeks of gestation. Hypertension is defined as a systolic blood pressure ≥140 mmHg or a diastolic blood pressure ≥90 mmHg on two occasions at least four hours apart. Proteinuria is defined as ≥300 mg of protein in a 24-hour urine collection or a protein/creatinine ratio of ≥0.3.

Other clinical features may include:

Severe headaches
Visual disturbances (e.g., blurred vision, photophobia)
Upper abdominal pain, often under the ribs on the right side
Nausea or vomiting
Decreased urine output
Shortness of breath, due to fluid in the lungs

Diagnosis

The diagnosis of preeclampsia is primarily clinical, based on the presence of hypertension and proteinuria. However, in the absence of proteinuria, preeclampsia can still be diagnosed if hypertension is accompanied by any of the following:

Thrombocytopenia (platelet count <100,000/microliter)
Impaired liver function (elevated blood levels of liver transaminases)
New development of renal insufficiency (serum creatinine >1.1 mg/dL or doubling of serum creatinine)
Pulmonary edema
New-onset cerebral or visual disturbances

Management

The management of preeclampsia depends on the severity of the condition and the gestational age at diagnosis. The only definitive treatment for preeclampsia is delivery of the baby and placenta. However, the timing of delivery must balance the risks to the mother with the risks of prematurity to the baby.

Mild Preeclampsia

In cases of mild preeclampsia, management may involve close monitoring of maternal and fetal well-being, including frequent blood pressure measurements, urine tests, and fetal ultrasounds. Bed rest and hospitalization may be recommended to ensure close observation.

Severe Preeclampsia

Severe preeclampsia requires more aggressive management, often including hospitalization and administration of medications to control blood pressure and prevent seizures (e.g., magnesium sulfate). In cases of severe preeclampsia, delivery is often recommended regardless of gestational age to prevent further complications.

Complications

Preeclampsia can lead to several serious complications, including:

Eclampsia: The occurrence of seizures in a woman with preeclampsia.
HELLP syndrome: A severe form of preeclampsia characterized by Hemolysis, Elevated Liver enzymes, and Low Platelet count.
Placental abruption: Premature separation of the placenta from the uterus.
Acute kidney injury
Pulmonary edema
Stroke

Prognosis

The prognosis for women with preeclampsia varies depending on the severity of the condition and the promptness of treatment. With appropriate management, most women with mild preeclampsia have good outcomes. However, severe preeclampsia can lead to significant maternal and fetal morbidity and mortality.

Prevention

There is no sure way to prevent preeclampsia, but several strategies may reduce the risk, including:

Regular prenatal care to monitor blood pressure and urine protein levels.
Maintaining a healthy weight and diet.
Managing pre-existing conditions such as hypertension and diabetes.
Low-dose aspirin therapy in high-risk women, as recommended by healthcare providers.