Tuberculosis (TB) is a contagious disease caused by the bacterium Mycobacterium tuberculosis, primarily affecting the lungs. It spreads through the air when an infected person coughs, sneezes, or talks. Understanding the safety and necessity of TB testing during pregnancy is important. This article clarifies when TB testing is recommended and the safety of available tests for pregnant individuals.
Reasons for TB Testing During Pregnancy
Healthcare providers may recommend tuberculosis testing for pregnant individuals to ensure both maternal and fetal health. One primary reason is potential exposure to someone with active TB disease. Individuals who have recently traveled from or resided in countries with a high incidence of TB are also considered at higher risk and may be advised to undergo testing.
Symptoms suggestive of active TB infection, such as a persistent cough lasting more than three weeks, unexplained weight loss, fever, or night sweats, also warrant immediate evaluation. Additionally, high-risk groups, including healthcare workers, individuals with weakened immune systems (e.g., due to HIV), or those with previous positive TB test results, often necessitate testing. Identifying and managing TB during pregnancy helps prevent potential transmission to the newborn and complications for the mother.
Safety of TB Tests for Pregnant Individuals
Two primary methods are generally used for tuberculosis testing during pregnancy: the Tuberculin Skin Test (TST) and Interferon-Gamma Release Assays (IGRAs). Both are considered safe for pregnant individuals and their developing babies. Neither test involves live bacteria, radiation, or other substances that could pose a risk to the fetus.
The TST, also known as the Mantoux test, involves injecting a small amount of purified protein derivative (PPD) under the skin of the forearm. A healthcare professional checks the injection site 48 to 72 hours later for a reaction, such as a raised, firm bump, which indicates exposure to TB bacteria. This method has been widely used and studied, showing no adverse effects on pregnancy outcomes.
Interferon-Gamma Release Assays (IGRAs), such as the QuantiFERON-TB Gold Plus or T-SPOT.TB test, are blood tests that measure the immune system’s reaction to TB bacteria. A blood sample is drawn and sent to a laboratory for analysis. These tests are not affected by prior BCG vaccination, which can sometimes cause a false positive result with the TST, and they are also considered safe for use during all trimesters of pregnancy.
Interpreting Test Results and Next Steps
Interpreting tuberculosis test results during pregnancy involves understanding what a positive or negative outcome signifies and the subsequent steps. A negative TST or IGRA result typically indicates that the individual does not have a TB infection. However, in rare instances, a false negative result can occur, particularly in individuals with severely weakened immune systems.
Conversely, a positive TST or IGRA result indicates exposure to Mycobacterium tuberculosis bacteria. This does not necessarily mean they have active TB disease; it could signify a latent TB infection (LTBI), where the bacteria are present but inactive. Further evaluation is necessary to distinguish between latent infection and active disease.
This assessment often includes a medical history review, a physical examination, and a chest X-ray. If a chest X-ray is required during pregnancy, it is performed with abdominal shielding to minimize radiation exposure to the fetus, ensuring safety. Sputum tests may also be conducted to confirm active disease.
TB Treatment Considerations During Pregnancy
If a pregnant individual is diagnosed with latent TB infection (LTBI) or active TB disease, treatment is recommended to safeguard both the mother and the fetus. Treating LTBI during pregnancy prevents its progression to active disease, which poses serious health risks to the mother and can lead to congenital tuberculosis in the newborn. The decision to initiate LTBI treatment is carefully weighed, considering the trimester and progression risk.
For active TB disease during pregnancy, treatment is always recommended and should not be delayed due to illness severity and transmission risk. Standard anti-TB medications are typically used, but the specific regimen and duration may be adjusted by healthcare providers for the safest and most effective approach. Consulting specialists, such as infectious disease and maternal-fetal medicine experts, is important to tailor the treatment plan, manage potential side effects, and monitor the health of both mother and fetus throughout the treatment period.