Is it normal to have a negative disease screening test?

In most cases, a negative disease screening result is a normal result, which means that the subject's screening did not detect any abnormalities related to the corresponding disease. However, it does not mean that the possibility of disease is 100% ruled out. A comprehensive judgment must be made based on the screening items, examination timing, and personal symptoms.

Over the years I have been doing public health education in the community, I have met many people who go to two extremes after receiving screening results. Either they think that negative means they are completely healthy, so they stay up late and eat and drink to build their bodies, or they are so anxious about the extremely low probability of false negatives that they can't even eat. Last year, when the district organized early screening for lung cancer, I met Uncle Zhang, an old smoker. On the day he received the negative low-dose CT report, he had a drink with his friends and said that his lungs were fine and he didn’t need to quit smoking. However, less than eight months later, he was diagnosed with a 1cm early-stage adenocarcinoma due to repeated chest pains. When he looked back at the previous images, he discovered that the small nodules on his lungs were hiding in the blind spot of the scan behind the heart. In addition, the density of the nodules was too low to be identified, which is a typical false negative situation.

This does not mean that negative results cannot be trusted. For example, if you are screening for very mature pathogens such as hepatitis B surface antigen and HIV antibodies, if the test is negative after the official window period, it basically means that there is no infection. This kind of negative result can be assured, and there is no need to go to the hospital repeatedly for re-examination. But if you already have corresponding discomforts, such as constant acid reflux and stomach pain, and the Helicobacter pylori breath test is negative, don't rush to the conclusion that you have "no stomach problems". It may be that you took omeprazole, antibiotics and other drugs half a month before the examination, which inhibited the activity of the flora, causing deviations in the results. It is best to tell the doctor about your specific symptoms and adjust the examination items to be more secure.

In fact, disease screening simply means using a fishing net of a fixed size to fish for "abnormal signals" in your body. The size of the mesh is determined based on the disease threshold of most people. A negative result means that no abnormality that meets the standard was caught during this fishing. It may be that there is really no problem in the body, or it may be that the abnormality is too small and just got stuck in the mesh.

In fact, there is no need to worry about whether this "normal" is absolute or relative. Relax when you get a negative result. If you have persistent discomfort, take the report to the doctor and ask more questions. Don't throw away the healthy habits that you should maintain. It is more reliable than anything else.