A lumbar puncture (a puncture in the lower back) is performed to check the composition and pressure within the cerebrospinal fluid. A negative result means that there are no abnormalities as in a normal person, while a positive result indicates that one or more of these items are abnormally elevated or lowered. When positive, there is usually an increase in cerebrospinal fluid white blood cells, an increase in pressure, or an electrolyte imbalance. Possible disorders include inflammatory intracranial diseases such as encephalitis and meningitis, as well as postoperative infections, and a lumbar puncture may be positive. The presence of infection is determined by retaining cerebrospinal fluid by lumbar puncture and observing for elevated white blood cells in the cerebrospinal fluid. And sometimes further tests, including things like cryptococcal infection and tuberculosis smear-related conditions, are performed to better identify the causative agent. Cancer cells can also be examined by lumbar puncture, such as when craniotomy is performed, the surgery performed is more traumatic, lumbar puncture can be performed, and cerebrospinal fluid can be retained, if tumor cells are detected, it can also effectively improve the patient’s status and achieve a better diagnostic determination. If lumbar puncture is needed, please consult the hospital in time and choose the appropriate examination and treatment method under the doctor’s guidance to avoid delaying the condition.