Lab tests to diagnose preeclampsia are simple and confirmatory. They allow for prompt treatment, which can save the mother and fetus from consequences that can be fatal.
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 followed by subsequent prompt treatment reduces morbidity and mortality of both the mother and the baby. Nutritional intervention also plays an important role in its management.
Preeclampsia affects about one in 10 pregnancies worldwide and one in 50 pregnancies, very severely. Pre-eclampsia can be mild and severe. Severe preeclampsia 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 the 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), a 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 signs 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.
Lab tests to diagnose preeclampsia is based on the following criteria:
History
There are certain risk factors that contribute to eclampsia. If you have any of these factors, your doctor will know that a positive personal and family history poses a potential danger to you vis-a-vis preeclampsia.
- The incidence of preeclampsia in primiparas is twice as high compared to multiparous women. Primiparity means giving birth for the first time.
- 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 late onset in the present pregnancy.
- Family history, too, is a risk. If your mother had pre-eclampsia, you, as the daughter have a 25% increased risk of developing the condition. Similarly, if your sister had pre-eclampsia, there is a 35% increased chance of developing it.
Symptoms and signs
There are several signs and symptoms of preeclampsia in the pregnant woman such as headaches, visual disturbances, photophobia, abdominal pain due to liver involvement, proteinuria, and more.
The cardinal sign to diagnose preeclampsia is persistently high blood pressure above 140/90 mm Hg that develops in a woman during pregnancy or the postpartum period. This gives a pretty sure reason to your doctor to investigate you for preeclampsia.
Urine test on a 24-hour sample
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.
For this investigation, a 24-hour urine sample is collected and tested for the presence of protein. However, at times, though preeclampsia is present, proteinuria may be absent.
Home test for protein in urine. You can test for the presence of protein or albumin at home using a simple protein urine dipstick test. The test kit provides 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.
Imaging tests
- 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 in the eye that are suggestive of preeclampsia. These visual disturbances include 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 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 case preeclampsia complications in the fetus have developed.
- Non-stress test. This is a simple noninvasive test that is done post-28 weeks gestation. It records your baby’s movement, heartbeat, and 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.