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Preeclampsia

Overview

Preeclampsia is a disorder that only affects pregnant women after twenty weeks of pregnancy. It causes hypertension and the appearance of proteins in urine. The underlying mechanism is related to the blood vessel wall dysfunction(vascular endothelium) and vasospasm, which damages the kidneys and, in severe cases, can harm other organs, such as the brain and the liver. Rarely, it develops six weeks after delivery.

Causes

The exact cause is unclear, but a key feature is the development of an abnormal placenta. Normally during pregnancy, the spiral arteries of the uterus dilate ten times their normal size and become large uteroplacental arteries that can deliver large quantities of blood to the developing fetus. In preeclampsia, these arteries become fibrous, causing them to narrow, which means less blood gets to the placenta. A poor bloody supply to the placenta leads to intrauterine growth restriction and even deaths of the fetus. In severe cases, this poorly supplied placenta releases pro-inflammatory proteins that enter into the mother’s circulation and cause endothelium, that line blood vessels, to become dysfunctional, which in turn causes vasoconstriction or narrowing of the blood vessel and majorly affects the kidneys in a way that makes them retain more salt. Vasoconstriction and salt retention result in hypertension.

There can be local areas of vasospasm which means less blood might reach certain parts of the body.

For example, reduced blood flow to the kidneys that are particularly susceptible can cause glomerular damage, leading to oliguria, which means an abnormally low amount of urine production, and proteinuria, which means protein in the urine. Usually, the kidneys do a pretty good job of preventing proteinuria, so proteinuria will indicate glomerular damage and is classically seen in preeclampsia. Reduced blood flow to the eye’s retina will cause blurred vision, a sensation of seeing flashing lights, and decreased vision. Reduced blood flow to the liver can cause severe liver damage. 10-20% of women with severe eclampsia have cardiovascular disease. 

Increased vascular permeability causes generalized edema. Pulmonary edema and cerebral edema are also seen.

Types

Based on severity, pre-eclampsia is divided into the following types;

  • Mild preeclampsia: high blood pressure, protein in the urine, and water retention.
  • Severe preeclampsia: headache, nausea, vomiting, blurred vision, fatigue, decreased urination, easy bruising, and difficulty breathing.

Risk Factors

  • First pregnancy has the highest risk of pre-eclampsia.
  • mothers who are suffering from high blood pressure 
  • those who suffer from migraines or Diabetes 
  • in women who tend to develop clots or lupus 
  • with a family history of preeclampsia 
  • Black women have a higher risk of developing eclampsia than women of other races.
  • The risk of preeclampsia is higher in obese women (overweight)
  • It is more common in women who are carrying twins or more.
  • If the baby is conceived with in vitro fertilization.

Epidemiology

Preeclampsia impacts 5-8% of all births in the U.S.

Signs And Symptoms

There can be a wide range of symptoms; for some women, there might be no symptoms whatsoever or only mild ones, whereas, for others, it can be life-threatening. The occurrence of seizures on the background of pre-eclampsia is called eclampsia. Epigastric pain is a severe cardinal symptom of preeclampsia 

  • Excess protein in the urine
  • Severe headaches 
  • Changes in vision 
  • Upper abdominal pain 
  • Nausea vomiting 
  • Impaired liver function 
  • Difficulty breathing
  • Weight gain, edema (swelling), particularly face and hands 

Diagnosis

Health care providers closely monitor pregnant patients' blood pressure, and urine as the first sign of developing preeclampsia is hypertension. When diagnosing preeclampsia, hypertension is defined as systolic blood pressure >140mm Hg and diastolic blood pressure >90mmHg.In severe preeclampsia, the systolic blood pressure is>160 mm Hg, and diastolic pressure can be >110mmHg. These extreme blood pressures can lead to hemorrhagic stroke or placental abruption, i.e.,  when the placenta detaches prematurely from the uterine wall.

Following tests aid in making the diagnosis;

  • CBC (Complete Blood Count)
  • Liver enzyme tests like; Aspartate aminotransferase (AST) levels and Serum alanine aminotransferase (ALT)
  • Serum creatinine to show kidney status
  • Uric acid
  • Urine dipstick analysis or 24-hour urine collection for protein and creatinine.
  • Preeclampsia can cause HELP syndrome: hemolysis, elevated liver enzymes, and low platelets. Tests to diagnose it are;
  • Indirect bilirubin
  • Peripheral blood smear
  • Serum lactate dehydrogenase (LDH) level
  • Ultrasonography: Transabdominal ultrasound is the standard test to check for fetal growth and abnormalities. 
  • Doppler ultrasonography: this test assesses blood flow in the umbilical artery. 
  • Cardiotocography (CTG): This test is used to monitor fetal activity.

Differential Diagnosis

Some disorders that can mimic pre-eclampsia are;

  • Lupus Nephritis 
  • Superimposed preeclampsia 
  • Hepato-renal syndrome 
  • Essential hypertension 
  • SLE
  • Appendicitis 
  • Diabetes insipidus 
  • Gall bladder disease 
  • Gastroenteritis 
  • Glomerulonephritis 
  • Haemolytic Uremic Syndrome 
  • Hepatic Encephalopathy.

Treatment

Because all the problems of eclampsia and preeclampsia stem from placental dysfunction, the ultimate treatment is delivery of the fetus and placenta. The patent diagnosed with pre-eclampsia is admitted to the hospital to monitor her health and blood pressure closely. The decision to induce delivery depends on how far along the pregnancy is, the severity of the disease, and how it affects the health of the mother and fetus. If the onset of symptoms happens after delivery, the goal is to manage the symptoms that slowly subside after delivery. Additional measures prevent end-organ damage by supplemental oxygen and medication to control seizures and other complications like stroke and placental abruption.

Medications

  • Emergency treatment of preeclampsia is done with IV hydralazine, labetalol, and oral nifedipine, which are blood pressure control medicines.
  • Methyldopa and labetalol tablets are considered first-line agents to control blood pressure in stable patients. 
  • Betamethasone and dexamethasone are steroids that are prescribed to help the fetus's lungs get mature.
  • Low-dose aspirin and Calcium supplements are also given in preventing preeclampsia in high-risk patients.
  • IV Magnesium Sulphate is given for seizures if they develop.

Prognosis

Most women deliver healthy babies and recover completely. However, preeclampsia in others can be life-threatening for both mother and the baby. The baby of a pre-eclamptic mother may be of low birth weight, maybe born preterm, or may have improper lung development. Some women experience complications. The risk of developing pre-eclampsia and its complications in successive pregnancies also increases.