Lumbar Puncture : Why is it done, Preparation And Results ?


A lumbar puncture, sometimes referred to as a spinal tap, is a diagnostic procedure used to pinpoint particular illnesses. Your lower back's lumbar region is where it occurs. A lumbar puncture involves inserting a needle between two lumbar vertebrae to obtain a sample of cerebrospinal fluid. In order to protect your brain and spinal cord from injury, this fluid surrounds them.

A lumbar puncture can be used to identify dangerous infections like meningitis, as well as multiple sclerosis and Guillain-Barre syndrome, various conditions of the central nervous system, hemorrhage, and malignancies of the brain or spinal cord. The cerebrospinal fluid may occasionally be injected with chemotherapeutic or anesthetic medicines through a lumbar puncture.

Why is it done?

A lumbar puncture or spinal tap may be carried out to:

  • To check for infections, inflammation, or other disorders, collect cerebrospinal fluid.
  • Check the cerebrospinal fluid pressure.
  • Inject chemotherapeutic medicines, spinal anesthetics, or other treatments
  • Cerebrospinal fluid can be injected with dye (myelography) or radioactive materials (cisternography) to provide diagnostic pictures of the fluid's flow.

A lumbar puncture can provide information that can be used to diagnose:

  • Serious cases of syphilis, encephalitis, meningitis, and other bacterial, fungal, and viral diseases
  • Brain bleeding all over (subarachnoid hemorrhage)
  • Brain or spinal cord tumors that are specific
  • Multiple sclerosis and Guillain-Barre syndrome, are two inflammatory disorders of the nervous system
  • Neurological autoimmune diseases
  • Dementias such as Alzheimer's and others

Risk Factors

While lumbar puncture (also known as a spinal tap) is usually regarded as safe, there are certain dangers involved. They consist of:

Headache after lumbar puncture. Up to 25% of patients who have a lumbar puncture get a headache the next day as a result of fluid seeping into the surrounding tissues.

Usually occurring several hours to two days following the treatment, the headache may also be accompanied by nausea, vomiting, and dizziness. The headaches typically appear when standing or sitting and disappear after resting down. Headaches following lumbar puncture might linger for several hours to a week or more.

Back pain or discomfort. After the treatment, your lower back may be sore or painful. You could feel the discomfort traveling down the backs of your legs.

Bleeding. Bleeding may happen close to the epidural space or the puncture site.

Herniated brainstem. Once a sample of cerebrospinal fluid is taken, increased pressure inside the skull brought on by a brain tumor or another space-occupying disease may cause the brainstem to become compressed. Before a lumbar puncture, a computed tomography (CT) or magnetic resonance imaging (MRI) scan is frequently conducted to check for any indication of a space-occupying lesion that might increase intracranial pressure and prevent this uncommon consequence. A thorough neurological examination can also aid in ruling out a big lesion that takes up a lot of space.


Your doctor will do a physical exam, review your medical history, and request blood tests to look for clotting or bleeding issues before performing a lumbar puncture (spinal tap). To check for any abnormal swelling in or around your brain, your doctor could also advise a CT scan or MRI.

Medicines and food

You will receive detailed directions about what to eat, drink, and take in from your healthcare practitioner.

If you use any anticoagulants or blood thinners, let your doctor know. Warfarin (Jantoven), clopidogrel (Plavix), and apixaban are among examples (Eliquis). Tell your doctor if you have any pharmaceutical allergies, especially if you have a numbing medicine allergy (local anesthetics).

A lumbar puncture (spinal tap) is often performed at a hospital or an outpatient clinic. Your doctor will go over the possible dangers and any discomfort you could experience during the treatment with you.

In rare circumstances, a parent may be permitted to remain in the room while their child is getting a lumbar puncture. Find out if this is feasible by speaking with your child's doctor.

Before Procedure

Although sometimes you can undergo the surgery while wearing your own clothes, you could be required to change into a hospital gown. Many locations can be used to do a lumbar puncture (spinal tap). Typically, you sit and lean forward on a firm surface or lie on your side with your legs pushed up to your chest. By flexing your back in these positions, your doctor will have an easier time inserting the needle since the gaps between your vertebrae will be wider. A sterile sheet is placed over your back after it has been cleaned with antiseptic soap or iodine.

Someone will keep a young child or a newborn in place throughout the process.

During Procedure

Before the needle is put in, a local anesthetic is administered to your lower back to numb the puncture site. As it is administered, the local anesthetic will temporarily hurt.

Between the two lower vertebrae (lumbar area), a thin, hollow needle is inserted. It then passes through the dura mater (spinal membrane) and into the spinal canal. During this phase of the treatment, your back may feel pressure.

You might be requested to slightly adjust your position once the needle has been inserted.

After measuring the pressure of the cerebrospinal fluid, a little quantity of CSF is removed, and the pressure is then measured once more.

The puncture site is bandaged once the needle has been taken out.

Typically, the process takes 45 minutes. After the operation, your healthcare expert could advise resting down.

While doing a lumbar puncture on newborns and young children, an ultrasonography may occasionally be utilized as a guide. The ultrasonography can assist in avoiding over-needling.

After Procedure

Schedule a nap. Avoid physically demanding activities on the day of your lumbar puncture (spinal tap). If your employer does not need you to be physically active, you can go back to it. If you have any concerns, talk to your healthcare professional about your activities.

Use a pain reliever. Back discomfort or a headache may be lessened by acetaminophen-containing over-the-counter pain relievers (Tylenol, etc). Call your healthcare practitioner if your headache worsens.


The spinal tap's spinal fluid samples are taken and forwarded to a lab for examination. While testing spinal fluid, lab workers look for a variety of items, including:

Appearance in general. Typically, spinal fluid is transparent and colorless. Orange, yellow, or pink in hue might suggest irregular bleeding. Green spinal fluid may be a sign of an infection or that bilirubin is present.

Protein. More than 45 mg/dL (elevated levels of total protein) are indicative of an infection or other inflammatory disease. Medical facilities may differ in their specific testing results.

The white blood cells. In a typical microliter of spinal fluid, there are up to five white blood cells. Increasing numbers might mean an illness, such as an infection. Medical facilities may differ in their specific testing results.

Sugar (glucose). A tumor, infection, or another illness might be indicated by a low glucose level in spinal fluid.

Microorganisms. An infection can be detected by the presence of bacteria, viruses, fungi, or other microbes.

Tumor cells. Some kinds of cancer may be indicated by the presence of aberrant cells in spinal fluid, such as tumors or immature blood cells.

To assist in making a potential diagnosis, laboratory findings are paired with data from the test, such as the pressure of the spinal fluid.

The findings are often sent to you by your doctor within a few days, although it can take longer. Inquire as to when you may anticipate getting your test results.

Make a list of questions. You should speak with your doctor about this. Do not be afraid to ask any more questions that may arise throughout your stay. You might wish to ask the following questions:

What actions should I take in light of the results?

What sort of follow-up, if any, ought I to anticipate?

Are there any variables that might have impacted this test's outcomes and perhaps changed them?

Will I eventually have to take the test again?

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Page last reviewed: Mar 17, 2023

Next review due: Mar 17, 2025

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