A positive tuberculosis screen during a USCIS Form I-693 exam does not, by itself, stop an adjustment of status case. But it does trigger a specific, well-defined sequence — starting with a chest x-ray immigration medical exam requirement — that every applicant should understand before walking into the civil surgeon's office. The path from a positive blood test to a signed I-693 can take anywhere from a few extra minutes to several months, and which one it is depends almost entirely on what the x-ray shows.
When USCIS Actually Requires a Chest X-Ray
Since October 1, 2018, USCIS no longer accepts the older tuberculin skin test (TST) as the primary TB screening method for the I-693. Civil surgeons now use an interferon-gamma release assay (IGRA) blood test — QuantiFERON or T-Spot — for applicants age two and older. A chest x-ray becomes mandatory whenever any of the following applies:
- The IGRA blood test comes back positive.
- The applicant shows signs or symptoms suggestive of active TB disease, regardless of test result.
- The applicant has a known HIV infection.
- For children under two, there has been documented contact with someone known to have TB, or another specific reason to suspect infection.
An IGRA test that comes back negative in an otherwise healthy applicant with no symptoms typically ends the TB portion of the exam right there — no imaging needed. It's the positive result that opens the next chapter.
Why a Positive Blood Test Isn't the Whole Story
A positive IGRA confirms that someone's immune system has encountered TB bacteria at some point. It says nothing about whether that infection is currently active, contagious, or even still present in a form that requires treatment. That distinction — latent infection versus active disease — is exactly what the chest x-ray is ordered to resolve, and it's why the civil surgeon cannot skip straight from a positive blood draw to a completed form.
What the X-Ray Determines: Three Possible Classifications
Once the chest x-ray is read, the civil surgeon assigns a TB classification. This is the fork in the road that decides how much further follow-up is needed before Form I-693 can be signed.
| Classification | Chest X-Ray Finding | Additional Testing Required | Effect on I-693 Timeline |
|---|---|---|---|
| Class B2 – Latent TB Infection | Normal, no symptoms present | None required to clear the exam; treatment is recommended but not mandatory | Minimal — the civil surgeon can generally complete the form the same visit |
| Class B1 – Extrapulmonary TB | Normal, but TB present outside the lungs | Three sputum specimens for smear and culture | Delayed until culture results return |
| Class A – Active TB Disease | Abnormal, suggestive of infectious TB | Full sputum workup plus completed treatment | Significant — often several months |
If the X-Ray Is Abnormal: Health Department Referral and Sputum Testing
When the chest x-ray is abnormal or suggestive of TB, the civil surgeon cannot classify the applicant, issue a medical clearance, or sign any part of Form I-693 independently. Federal guidance requires the applicant to be referred to the local health department of jurisdiction for further evaluation. The civil surgeon has to wait for that agency to send back documentation before the exam can move forward.
If active pulmonary TB is suspected, sputum specimens are collected for smear and culture analysis. A molecular test (nucleic acid amplification, or NAAT) is typically run on the first specimen for a faster preliminary read, but a definitive negative culture result still takes time to confirm:
- Liquid culture media require a minimum incubation period of about six weeks before a final negative can be reported.
- Solid culture media require roughly eight weeks.
- If active disease is confirmed, treatment must be completed and documented before clearance can proceed.
For an applicant ultimately classified as Class A — active, infectious TB — the civil surgeon will not sign the I-693 until written confirmation arrives from the health department that treatment is complete and sputum cultures are negative. That confirmation, realistically, can push the timeline out by several months.
What This Means for Planning Your Filing
The practical takeaway for anyone going into an immigration medical exam: a positive TB screen is common, and in most cases — a normal x-ray, no symptoms, Class B2 latent infection — it adds very little time to the process. The delay only becomes significant when the x-ray itself is abnormal, because that shifts the case out of the civil surgeon's office and into a public health department's queue for culture results that take weeks to finalize by design, not by bureaucratic slowness.
A few things worth knowing going in:
- A positive TB test does not automatically make someone inadmissible. Admissibility turns on whether active, contagious disease is present and how it's being managed, not on the positive blood test alone.
- Pregnant applicants can generally defer the chest x-ray until after delivery, but the civil surgeon still cannot finalize Form I-693 until the x-ray is eventually taken, read, and any needed follow-up is closed out.
- If treatment for latent TB is recommended but not completed, it typically doesn't block the I-693 itself, but a civil surgeon may note the incomplete follow-up on the record.
Because these timelines depend on which health department is involved and how quickly lab results come back, it's worth asking a civil surgeon early — ideally before the appointment even starts — how their office typically handles referrals and how long culture turnaround has been running locally. Knowing the range in advance turns what feels like an open-ended delay into a plannable step in the filing process.