A positive TB blood test during your immigration medical exam does not automatically prevent you from getting a green card. In most cases, a positive result means you have latent TB infection, which is not contagious and is not grounds for inadmissibility. Your civil surgeon will need to run additional tests to determine whether you have latent infection or active disease, and the distinction between those two makes all the difference for your case.
What Happens Right After a Positive Blood Test
The immigration medical exam uses a blood test called an IGRA (interferon-gamma release assay) to screen for TB. If your result comes back positive, the next required step is a chest X-ray. The X-ray is read by a board-certified radiologist and reviewed by your civil surgeon to look for signs of active TB disease in your lungs. For adults and children 10 and older, this is a single standard chest image. Children under 10 need an additional side-view image.
If the chest X-ray looks normal, your case most likely falls into the latent TB category. If the X-ray shows anything suggestive of active TB, or if you have symptoms like a persistent cough, fever, or unexplained weight loss, you’ll need to provide sputum samples (mucus coughed up from your lungs) for laboratory testing. The first sample also undergoes molecular testing for faster results, though full cultures can take several weeks to come back.
Latent TB: Classification and What It Means for Your Case
If your blood test is positive but your chest X-ray is clear, you’re classified as “Class B2 TB, Latent TB Infection.” This is the outcome most people with a positive test receive, and it’s the most important thing to understand: latent TB infection is not a Class A condition. Class A conditions make you inadmissible. Latent TB does not.
Because latent TB is not infectious, treatment is not required for status adjustment. Your civil surgeon can sign your Form I-693 (the official medical exam report) and hand it to you without waiting for you to start or finish any TB treatment. The form can be completed and given to you before any follow-up happens. Your immigration case moves forward on its normal timeline.
That said, your civil surgeon is required to report your latent TB diagnosis to your local health department. They will also strongly advise you to get treated, because latent TB can develop into active disease later in life, which is a serious health risk for you and the people around you. Treatment is in your best interest even though it’s not an immigration requirement. Your civil surgeon can either treat you directly or refer you to another provider.
Active TB: What Changes
If your chest X-ray suggests active TB disease, or if your sputum samples confirm it, you’re classified as “Class A TB.” This is a communicable disease of public health significance, and it makes you inadmissible to the United States. Your civil surgeon cannot sign your Form I-693 until the required referral, testing, and treatment steps are complete, which the CDC notes can be a lengthy process.
Active TB that has been fully treated is a different story. Once you’ve completed treatment and are no longer infectious, the Class A designation is lifted. If you’re diagnosed during your medical exam, you’ll need to work through the treatment process before your paperwork can be finalized. For applicants who need to move forward before treatment is fully complete, federal regulations allow for a waiver of inadmissibility using Form I-601. The waiver requires documentation that a physician or health facility has agreed to provide treatment or observation, and in some cases a statement from a local or state health officer.
Why the Blood Test May Be Positive Even Without Infection
Many immigration applicants received the BCG vaccine as children, which is a TB vaccine widely used outside the United States. If you had the older-style skin test (tuberculin skin test) in the past, the BCG vaccine frequently caused false-positive results. In one large study of immigrant children, almost two-thirds of those with positive skin test results had negative results on the newer IGRA blood test, meaning their skin test positives were likely caused by BCG vaccination rather than actual infection.
The current immigration guidelines require the IGRA blood test specifically because it’s far less affected by prior BCG vaccination. Discordant results (positive skin test, negative blood test) were found in about 20% of cases in research on resettling children, and 95% of those discordant cases pointed to the skin test being falsely positive due to BCG. So if you had a positive skin test years ago but your IGRA blood test is negative, the blood test result is what counts for your immigration exam. If your IGRA is positive, though, it’s treated as a real result regardless of BCG history.
How This Affects Your Form I-693 Timeline
For latent TB, the impact on your timeline is minimal. Your civil surgeon documents the positive IGRA result, notes your treatment status, and signs the form. If you’ve had multiple IGRAs over the years, all dates and results must be documented. If you’ve previously completed treatment for latent TB or active TB disease and have documentation, that history is noted and you move forward.
For active TB, expect significant delays. You cannot receive a signed I-693 until the referral evaluation from the health department is completed and returned to your civil surgeon. Treatment for active TB typically takes several months, and your immigration case is effectively paused until you’re medically cleared.
One additional timing detail worth knowing: as of November 2023, USCIS changed the validity rules for Form I-693. A signed form is now only valid while the specific immigration application it was submitted with is pending. If that application is withdrawn or denied, the I-693 is no longer valid and you’d need a new medical exam for any future application. This makes it important to have your TB situation resolved before your civil surgeon signs, so you don’t burn through a valid form on a case that stalls for other reasons.
What Gets Reported to the Health Department
Every applicant classified as Class B2 (latent TB) must be reported to the health department in the jurisdiction where they live. This is a public health reporting requirement, not an immigration enforcement action. The health department may follow up with you to offer treatment resources or monitoring, but this reporting does not feed into your immigration case in a negative way. Your civil surgeon is required to inform you that this report will be made.
For applicants with active TB (Class A), the health department involvement is more hands-on. The referral process between your civil surgeon and the health department is a formal step that must be completed before your medical paperwork can be finalized. The health department’s evaluation section must be filled out and returned to the civil surgeon before the I-693 is signed.