What Happens at a Clinical Trial Screening Visit?

By: David Grew MD MPH

"A clinical trial screening visit is really about two things: fit and safety."

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Before a patient can officially join a clinical trial, there is usually a screening process. The purpose of screening is to find out whether the trial is a good match and whether it is safe for that patient to participate. Participation begins after screening and informed consent, and that each trial has its own rules about visits, procedures, and time commitment.

For many patients, the screening visit is where the trial starts to feel real. It is also the point where it becomes easier to understand what joining the study would actually involve.

Why is there a screening visit?

Every clinical trial has eligibility criteria. These are the rules that say who can and cannot join. They may include things like the type of cancer, stage, prior treatments, age, lab values, medical history, and current health status. The goal is both to protect patient safety and to make sure the study is being tested in the right group of people.

That means a screening visit is not just paperwork. It is a medical check to confirm whether the study fits the patient’s situation.

What usually happens before the visit?

Before or during screening, patients are usually given information about the study and the informed consent process. Before joining a cancer research study, patients receive an informed consent form to review, ask questions about, and sign. The form covers the study’s purpose, procedures, safety measures, and what is expected of participants.

This is an important point: signing the consent form does not always mean a patient is definitely enrolled yet. Screening may still show that the patient does not meet the trial’s requirements. That is one reason patients should think of screening as an evaluation step rather than a final commitment.

What kinds of questions might the team ask?

At a screening visit, the research team may review:

• medical history
• cancer diagnosis and stage
• past treatments
• current medicines
• symptoms and side effects
• general health status

This information helps confirm whether the study is appropriate and safe. Eligibility screening is used to check medical criteria and protect participants.

What tests might be done?

The exact tests depend on the trial, but screening may include things like:

• blood tests
• urine tests
• imaging scans
• heart tests in some studies
• biopsy review or additional tissue testing in some situations
• physical exam and vital signs

People in treatment trials may have more tests and more doctor visits than they would with standard treatment alone.

How long does screening take?

There is no single timeline. Some screening can happen in one visit, while other trials may require multiple appointments over days or weeks. Where a trial is located, what procedures are involved, and how many visits are needed differ from study to study, so the time commitment varies.

That is why it is reasonable to ask upfront:

• How many visits are needed?
• What tests happen at screening?
• How long does the process usually take?
• When would treatment actually start if I qualify?

Does screening mean I am definitely getting the treatment?

No. Screening is used to determine whether a patient is eligible. Some patients go through screening and then learn that they do not meet the study requirements. This can happen for medical, lab, imaging, or timing reasons. Eligibility criteria are built into the trial protocol for safety and scientific reasons.

It can feel disappointing, but it is a normal part of the research process.

What should patients bring or prepare?

The trial team will usually tell patients what they need, but common things to have available may include:

• medication list
• outside records or imaging if requested
• insurance information
• contact information for treating doctors
• a list of questions for the study team

Because the informed consent process is part of screening, many patients also find it helpful to bring a family member or friend to help listen and take notes. Patients should review the consent form and ask questions before deciding whether to join.

What happens after screening?

If a patient meets the study requirements and still wants to participate, the next step is usually enrollment and then starting the study treatment or procedures. If the patient does not qualify, the regular oncology team can still help discuss other treatment options. NCI’s clinical trial guidance emphasizes that trials are only one part of cancer care and that patients should discuss the search results and decisions with their doctor.

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A clinical trial screening visit is really about two things: fit and safety. The research team is checking whether the study matches the patient’s cancer and medical situation, and the patient is deciding whether the study feels right for them. Trial participation involves screening, informed consent, and ongoing monitoring, and that each study has its own procedures and schedule.

For patients, one of the best ways to prepare is to come with questions. Understanding what the screening visit involves can make the process feel less overwhelming and more manageable.

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FAQs:

Does signing the consent form mean I am officially in the trial?

No. Signing informed consent usually means you agree to begin the screening and enrollment process, but you may still need tests or reviews to confirm that you meet the study’s requirements. If you are unsure where you are in the process, ask the study team whether you are still in screening or already enrolled.

Can I be told no after a screening visit?

Yes. A patient can go through screening and still be found ineligible if the trial’s medical criteria are not met. That can happen because of lab results, scan findings, prior treatments, current health status, or other eligibility rules. If that happens, ask your care team whether another trial or a standard treatment option may be a better fit.

Will I probably need extra blood tests or scans during screening?

Yes, possibly. Clinical trials often involve more tests and doctor visits than standard treatment, and screening is when many of those checks happen to confirm safety and eligibility. Ask the study team which tests are required before treatment can begin and whether any can be done locally.

Can I change my mind during the screening process?

Yes. Joining a clinical trial is voluntary, and patients may leave at any time. If you start screening and then have concerns, contact the study team or your oncology team so they can explain what stopping would mean for your care and next steps.

Should I still tell the study team about symptoms that seem minor?

Yes. Even symptoms that seem small may matter during screening because the team is checking whether the trial is safe and appropriate for you. Patients should also report changes in medications, recent illnesses, or new medical events so the study team has the most accurate information. If anything changes before enrollment, contact your care team and the research team.

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