How Is Preeclampsia Diagnosed? An OBGYN Explains

Preeclampsia is one of those pregnancy complications that many people have heard of—but the actual diagnosis can feel confusing.

Is it simply high blood pressure? Do you have to have protein in your urine? What do headaches, blood tests, eclampsia, and HELLP syndrome have to do with it?

As a board-certified OBGYN, I want to walk through how clinicians put these pieces together. The short version is that preeclampsia is more than a single blood pressure reading, and protein in the urine is important—but it is not required in every case.

What is preeclampsia?

Preeclampsia is a pregnancy-related hypertensive disorder. It usually develops after 20 weeks of pregnancy and involves new high blood pressure plus evidence that another part of the body may be affected.

That “other evidence” might be protein in the urine, concerning symptoms, or abnormal laboratory results involving the kidneys, liver, or blood platelets.

Preeclampsia can also first appear after delivery, so new concerning symptoms during the postpartum period deserve prompt attention too.

The first piece: elevated blood pressure

The starting point for a diagnosis of preeclampsia is new elevated blood pressure after 20 weeks of pregnancy in someone who did not previously have chronic hypertension.

A blood pressure of 140/90 mm Hg or higher is considered elevated in this setting. Clinicians generally confirm an elevated reading with another measurement, although severely high blood pressure may need to be confirmed and treated more quickly.

This is important because one isolated reading does not tell the whole story. Pain, anxiety, activity, an incorrectly sized cuff, and other factors can affect a measurement. Your care team looks at the number, whether it remains elevated, your gestational age, your history, and any other symptoms or test results.

High blood pressure after 20 weeks without the additional findings of preeclampsia may instead be called gestational hypertension. Because the condition can evolve, clinicians usually continue monitoring closely.

The classic combination: high blood pressure and protein in the urine

The combination most people associate with preeclampsia is:

• New high blood pressure after 20 weeks
• New protein in the urine, called proteinuria

Protein in the urine can be a sign that the kidneys are being affected. Your clinician may evaluate this with a urine protein-to-creatinine ratio, a timed urine collection, or another urine test depending on the circumstances.

For someone who already had chronic hypertension or protein in the urine before pregnancy, the diagnosis can be more complicated. The medical team may look for a significant change from the person's baseline or for new signs of organ involvement.

Can you have preeclampsia without protein in your urine?

Yes. This is one of the most important points to understand.

Proteinuria is not required when new high blood pressure occurs with other evidence that preeclampsia is affecting the body.

Those findings can include:

• A low platelet count
• Abnormal liver function
• Abnormal kidney function
• Fluid in the lungs, called pulmonary edema
• A severe, persistent headache that is not explained by another cause
• New vision changes
• Persistent pain in the upper abdomen, especially on the right side

This is why a urine dipstick alone cannot rule preeclampsia in or out. Clinicians consider the entire clinical picture.

Symptoms that deserve attention

Preeclampsia does not always cause noticeable symptoms. Sometimes elevated blood pressure at a prenatal visit is the first clue.

When symptoms do occur, they may include:

• A severe or persistent headache
• Blurred vision, flashing lights, spots, or another sudden vision change
• Pain in the right upper abdomen or upper stomach area
• Difficulty breathing or sudden shortness of breath
• Swelling of the face or hands, especially when it is sudden
• Nausea or vomiting later in pregnancy
• A sudden sense that something is seriously wrong

These symptoms can have causes other than preeclampsia. A headache in pregnancy, for example, does not automatically mean preeclampsia. The important point is that concerning symptoms—particularly when they are new, severe, persistent, or paired with elevated blood pressure—need medical evaluation.

What blood tests are used?

If preeclampsia is suspected, your medical team may order blood work to look for signs that the condition is affecting your organs.

Common tests include:

• Platelet count: A low count may indicate a severe feature and can affect the blood's ability to clot.
• Liver enzymes: Elevated levels may suggest liver irritation or injury.
• Creatinine: An elevated creatinine level may indicate that the kidneys are not functioning normally.
• Additional blood tests: Depending on the situation, clinicians may look for evidence of hemolysis, or the breakdown of red blood cells.

These results are interpreted alongside your blood pressure, urine testing, symptoms, medical history, and how far along you are in pregnancy.

What does “preeclampsia with severe features” mean?

Preeclampsia with severe features means there are findings that increase concern for serious complications and generally require more intensive monitoring and management.

Severe features can include:

• Severely elevated blood pressure
• Very low platelets
• Worsening kidney or liver function
• Severe persistent headache or vision changes
• Persistent upper abdominal pain related to the liver
• Fluid in the lungs

The phrase “severe features” is not based on how sick someone looks. A person can feel relatively well and still have concerning blood pressure or laboratory findings. That is one reason prenatal blood-pressure checks and recommended testing matter.

What is eclampsia?

Eclampsia occurs when someone with a pregnancy-related hypertensive disorder develops seizures that are not explained by another condition.

It is a medical emergency. Treatment focuses on stabilizing the pregnant or postpartum patient, preventing additional seizures, controlling dangerously high blood pressure when present, and determining the safest timing of delivery when the pregnancy is ongoing.

What is HELLP syndrome?

HELLP stands for:

• Hemolysis, or breakdown of red blood cells
• ELevated Liver enzymes
• Low Platelets

HELLP syndrome is considered a severe pregnancy complication and requires urgent medical care. It is often associated with preeclampsia, but the presentation is not always textbook. Some patients may not have dramatically elevated blood pressure when the condition first becomes apparent.

Possible symptoms include significant right upper abdominal or upper stomach pain, nausea or vomiting, headache, and feeling profoundly unwell or exhausted. Diagnosis relies heavily on laboratory testing.

When should you call your OBGYN?

Contact your obstetric care team promptly if you have concerns about an elevated blood-pressure reading or develop symptoms such as a severe headache, sudden vision changes, persistent upper abdominal pain, or difficulty breathing.

Seek urgent medical evaluation for severe or sudden symptoms, a seizure, chest pain, significant trouble breathing, or blood pressure in a range your clinician has told you requires immediate care.

Every practice has its own instructions, and your individual threshold for evaluation may differ based on your history. If you have been asked to monitor your blood pressure at home, make sure you know what numbers your care team wants you to report and where they want you to go after office hours.

The bottom line

Preeclampsia is not diagnosed from one symptom or one test.

Clinicians look for new high blood pressure after 20 weeks and then evaluate for protein in the urine, concerning symptoms, and changes in the blood work. Proteinuria is common, but preeclampsia can still be diagnosed without it when there is other evidence of organ involvement.

Understanding these criteria can make an intimidating diagnosis feel less mysterious. It can also help you understand why your care team may repeat your blood pressure, collect urine, order blood tests, or recommend additional monitoring even when you feel well.

Related White Coat Mama video: Am I at Risk for Preeclampsia?

Continue the White Coat Mama series

Explore next: Pregnancy & Postpartum: An OBGYN-Guided Resource Hub

Sources & Further Reading

• ACOG: Preeclampsia and High Blood Pressure During Pregnancy
• ACOG Practice Bulletin: Gestational Hypertension and Preeclampsia

Medical Disclaimer: This content is provided for general educational and informational purposes only and is not intended to be, and should not be considered, medical advice, diagnosis, or treatment. It does not create a physician-patient relationship. Medical decisions should be made with a qualified healthcare professional who knows your personal medical history. Always consult your own doctor or other qualified healthcare provider with questions about your health, symptoms, medications, pregnancy, or treatment options. If you believe you may be experiencing a medical emergency, seek emergency medical care immediately.