Disease screening should not take more than a few days at the latest

There has never been a unified standard answer to this question - an overdue period of 1-7 days for routine health screening will hardly affect the reference value of the results, and even delaying it for a month will not be a big problem.； However, the deadline for special inspections for infectious disease exposure, suspicious symptom screening, and early cancer screening for high-risk groups ranges from 72 hours to 6 months. Ultimately, it must be comprehensively judged based on the purpose of screening, personal risk level, and type of detection technology.

Last week, when I was volunteering for disease control in my jurisdiction, I met an elder sister who was sweating anxiously while carrying a physical examination bag. She forgot the time for the two cancer screenings organized by her work unit, and took 22 days to remember. She stood at the triage table and pulled me to ask if the screening was in vain. I happen to know Director Zhang who is responsible for the two cancer screenings at the physical examination center. She mentioned in our previous chat that this annual general screening for the general population is essentially a health baseline. As long as you do not have special symptoms such as abnormal vaginal bleeding or obvious breast lumps in the past 20 days, a delay of more than 10 or 20 days will not affect the reference value of the results at all. Of course, some institutions will require you to arrive strictly on the appointment time, and you will have to reschedule your appointment if you are one day away. In fact, most of them are afraid that they will occupy other people's physical examination quotas. It is not a hard requirement on the medical level, so don't worry too much.

But if you are doing targeted screening, you cannot be so casual. A few months ago, a young man came to ask about HIV screening after high-risk sexual behavior. I found two doctors for him, and the opinions were really different: the young doctor in the Department of Infectious Diseases said that the fourth-generation reagent currently used can detect 99.5% in four weeks. If the test is negative after four weeks, it can basically be ruled out. ； However, the veteran disease control experts still insisted on rechecking him in three months. This was not because of old ideas, but because he was afraid that if he encountered a very small number of people with extremely low immunity, the window period would be longer than that of ordinary people. There is no harm in being conservative. If it involves blocking after exposure, 72 hours is the golden period. Beyond this time, the success rate of blocking will drop significantly. This is an uncontroversial consensus in the industry. There are also screenings that require fresh samples, such as fecal occult blood and sputum smears. They must be sent for examination no more than 2 hours after sampling. If the sample is left for a long time, it will deteriorate and the examination will be in vain.

I used to think that all screenings had to be delayed until I had a meal with Brother Li from the Gastroenterology Department last time. He said that his routine colonoscopy was scheduled for half a year, and there was no delay. After all, he has no family history of bowel cancer, and has never had symptoms of blood in the stool or long-term constipation. He belongs to a low-risk group. Originally, he only needs to be checked once every 3-5 years, and it is not a problem at all if he is late for half a year. But if you already have clear discomfort, such as blood in the stool for a week, stomach pain that does not get better after taking medicine, and the doctor prescribes gastroenteroscopy or tumor marker screening, then do it no more than 7 days at the latest. Last year, there was a patient who had blood in his stool and the doctor asked him to undergo a colonoscopy. He was afraid of the pain and delayed it for three months. It was originally an adenomatous polyp that could be removed directly under the microscope, but it had developed into early cancer. Although it had not metastasized, he still had to undergo a partial intestinal resection. He suffered a lot for nothing.

As for the annual early screening of high-risk groups such as lung cancer and gastric cancer that many people are concerned about, such as low-dose lung CT for long-term smokers and annual gastroscopy for people with atrophic gastritis, it should not be more than 3 months at the latest - it is originally an annual screening. If you originally scheduled it in October, it is perfectly fine to postpone it to December. But if you postpone it directly to October of the next year, it is equivalent to not having it for two years, and there is a risk of missed diagnosis.

In fact, many people are obsessed with this "latest number of days". In essence, they either cannot spare the time, or they have an "ostrich mentality" and dare not go for fear of finding out the problem. But to be honest, if your body has given you a signal, delaying for one more day is a risk. ； If it's just a routine physical examination, and I don't have time to stay late for ten days and a half, there is no need to feel any psychological burden at all. After all, the essence of screening is to seek peace of mind. Instead of worrying about the number of days, it is better to make an appointment early, eat and sleep steadily after the test, which is worse than anything else.