Retention needles mostly refer to indwelling needles, which can theoretically remain in the human skin for up to about 6 days, but the actual retention time may vary depending on the needs of the disease diagnosis and treatment. The advent of indwelling needles has been a major boon to clinical patients, and their use is widespread. For patients requiring long-term intravenous infusions, the use of indwelling needles can reduce patient pain by avoiding repeated punctures of the blood vessels. However, indwelling needles should not be left in the patient’s body for long periods of time and can cause bacterial infections if not properly cared for. It also creates more work for the nursing staff because it requires them to do timely disinfection operations around the skin of the indwelling needle. Theoretically, indwelling needles can stay in the body for about 6 days, but they are usually removed in about 3 days clinically, even after 24 hours of treatment is completed in some patients. Patients are advised to take care of the cleanliness of the skin around the indwelling needle while it is retained to avoid infection.