History and Lab Tests to Diagnose Preeclampsia

Preeclampsia is the most common complication of pregnancy and also one of the most dangerous. Diagnosing it early with the help of history, symptoms and signs and lab tests reduces morbidity and mortality of both the mother and the baby.

It affects about one in 10 pregnancies worldwide and one in 50 pregnancies, very severely. Pre-eclampsia can be very serious and is presently responsible for the deaths of between three and five women a year as well as between 500 and 600 babies. Most of its complications can be fatal to mother and child.

The history and urine and blood lab tests can give you a conclusive diagnosis of this condition.

Previously, persistent high blood pressure and high levels of protein in urine were the two cardinal signs for the diagnosis of preeclampsia. Today, there is a new variant to these criteria for diagnosing preeclampsia.

According to guidelines released by the American College of Obstetricians and Gynecologists (ACOG), high level of protein in the urine (proteinuria) is no longer the diagnostic criteria for preeclampsia.

Preeclampsia affects most systems of the body and along with high blood pressure, damage to the body organs is an important finding for the diagnosis of preeclampsia.

Damage to the liver and the kidneys can occur without showing the sign of proteinuria. Therefore, proteinuria is now no longer considered a cardinal sign of preeclampsia diagnosis.

Secondly, the amount of protein in the urine does not evaluate the severity of the condition.

Diagnosis of preeclampsia is based on the following criteria:

History

If you have read the risk factors that contribute to eclampsia, you will know that a positive personal and family history pose a potential danger to you vis-a-vis preeclampsia.

  • Primiparity means giving birth for the first time. The incidence of preeclampsia in primiparas is twice as high compared to multiparous women.
  • Preeclampsia in a previous pregnancy increases the risk of preeclampsia in the next pregnancy by 10% to 50%. Early onset of preeclampsia (before 30 weeks) in the previous pregnancy increases the risk more than a late onset.
  • Family history too is a risk.  If the mother had pre-eclampsia, the daughter has a 25% increased risk of developing the condition. Similarly, if a sister had pre-eclampsia, there is a 35% increased chance of developing it.

High blood pressure

Persistent high blood pressure above 140/90 mm Hg that develops in a woman during pregnancy or the postpartum period is the main sign that indicates that preeclampsia has developed.

24-hour urine sample analysis

The presence of high amounts of protein in the urine greater than or equal to 0.3 grams in a 24-hour urine specimen, or a protein/creatinine ratio equal to or higher than 0.3 (in mg/dL) helps in the diagnosis of preeclampsia. However, at times, though preeclampsia is present, proteinuria may be absent.

Proteinuria home test for preeclampsia

You can test for the presence of protein or albumin at home using a simple protein urine dipstick test.

You use a dipstick made with a color-sensitive pad. You dip the color-sensitive pad into your 24-hour urine sample. The change of color on the dipstick pad tells you the level of protein in your urine.

A urine dipstick protein of 1+ (if a quantitative measurement is unavailable) is required to diagnose preeclampsia.

Blood tests

Complete Blood Count

Decreased platelet count in blood (Thrombocytopenia), a sign of preeclampsia, can be detected through a simple blood test called the complete blood count (CBC).

CBC showing thrombocytopenia with a platelet count of less than 100,000/uL in a pregnant woman is very indicative of this condition.

Kidney and liver function blood tests

These tests detect kidney or liver problems, which preeclampsia often causes.

Elevated blood concentrations of liver transaminases to twice the normal level indicate an impaired liver function.

Serum creatinine ≥1.1 mg/L or a doubling of the serum creatinine concentration in the absence of other renal diseases indicates kidney damage.

Chest x-ray

The chest x-ray shows fluid in the lungs (pulmonary edema) another important sign of preeclampsia.

Optical coherence tomography

Optical coherence tomography is of much importance in identifying the pathological changes responsible for visual disturbances such as cortical blindness, serous retinal detachment, retinopathy, and vitreous hemorrhages.

Fetal ultrasound

Periodic fetal ultrasound is done to monitor the weight and growth of the baby and to check if the there is a normal amount of amniotic fluid in the uterus. This is done to check the growth of the fetus, which can be restricted in a case of preeclampsia.

Non-stress test 

This is a simple noninvasive test that is done post 28 weeks gestation. It records your baby’s movement, heartbeat, and your uterine contractions.

It measures the changes in the heartbeats of the fetus when it moves. If the heartbeat increases by 15 beats or more in a minute for at least 15 seconds twice every 20 minutes, it indicates that everything is normal.

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