Blood collection site for disease screening

The preferred blood collection site for routine disease screening is the cubital vein at the antecubital fossa. In special scenarios and special groups, the dorsal hand vein, jugular vein, femoral vein, fingertip capillaries, heel capillaries and other sites will be selected based on actual needs. There is no "only correct" standard. Everything is based on the core principles of test accuracy and the tolerance of the person being blood collected.

If you have ever had a physical examination, you must have an impression. As soon as the nurse pulls your arm, she presses her fingers twice on the cubital fossa, looking for the most bulging and elastic blood vessel. It is not that the nurse is obsessed with the cubital fossa, but the blood vessels here are too "sensible" - thick and superficial, with no important nerves and arteries nearby. The risk of tying is extremely low. Even if you are a new nurse, as long as you find the right location, you will rarely have problems. Moreover, routine screening often requires taking three or four tubes to check liver function, blood lipids, tumor markers, infection, etc. The blood flow of the cubital vein is sufficient, and the tube can be collected in ten seconds, saving time and suffering.

Speaking of which, there is still a disagreement in the industry that has been quarreling for many years: Can fingertip blood for screening replace venous blood? Supporters are mostly grassroots public health practitioners. After all, when going to the countryside for large-scale screening, you can set up a table and prick your fingertips without rolling up your sleeves or looking for blood vessels. The efficiency can be doubled several times, especially when checking blood sugar for the elderly and doing preliminary blood screening for children in the mountains. As long as you don’t squeeze your fingers hard when collecting blood to avoid interstitial fluid mixing in, the error is completely within the acceptable range. However, most teachers in the laboratory department have reservations. There are too many factors that affect fingertip blood. If you have just come in from the cold outside or just clenched your fist for a long time, the results may be wrong. If it is used for screening of tumor markers and thyroid function that require high accuracy, it is easy to have false positives or false negatives, which will delay the test.

Of course not everyone can pierce the elbow socket. When I was helping at a community screening site two years ago, I met an old uncle who was almost 80 years old. He had worked hard at construction sites all his life when he was young. The blood vessels in the cubital fossa were as hard as thin plastic tubes. Even after two injections, he couldn't draw any blood. The uncle himself was worried. He said, "Girl, please prick the back of my hand, the blood vessels on the back of my hand are good." Later, I changed to an experienced nurse, who found a raised blood vessel on the back of my hand, and hit it with one needle. The old man said pricking the back of my hand was more painful than the elbow socket, but it was still better than receiving several injections.

Children are even more special. The elbows of children under two years old are as thin as lotus joints and are tightly wrapped in fat. The blood vessels cannot be touched at all. Generally, newborns are screened for genetic metabolic diseases by pricking the heels. The capillaries are rich enough. A few drops are enough for detection, and the damage to the baby is minimal. If an older baby cannot find a blood vessel in the upper limb, the jugular vein or femoral vein may also be used. Even if the parents feel distressed, they always feel that piercing the neck and piercing the thighs is risky. In fact, they are all professionally trained and rarely cause problems.

I once met a little girl who rolled up her sleeves and exposed her wrists as soon as she sat down. She said, "Nurse, just prick her here. You can't see the blood vessels in my elbow fossa." The nurse was so frightened that she waved her hand quickly. The area on the inside of her wrist was next to the radial nerve. If it was pricked, it was common for her to be numb for several months. Unless she couldn't find other blood vessels, no one would put a needle in that place.

To put it bluntly, there are no hard and fast rules when it comes to choosing a blood collection site. The experience of the experienced nurse, the actual situation of the person being blood collected, and the accuracy requirements of the screening project all come together to determine where the needle should be inserted. Of course, if you have experienced needle fainting, difficulty finding blood vessels, or problems with a certain part of the needle before, tell the nurse in advance, which can save you a lot of trouble~