Print this page

Lumbar puncture under X-ray control

A lumbar puncture (LP) is a procedure used to obtain a sample of cerebrospinal fluid (CSF). CSF is the fluid that bathes and protects the brain and spinal cord. It is produced constantly, so that the small amount removed during an LP is rapidly replaced.

CSF testing can provide your doctors with information about how the brain and spinal cord is working. When this is combined with a history, examination and scan
results, an LP can sometimes help to diagnose a wide range of neurological conditions.

An LP is not compulsory. However, if an LP isn’t performed your doctors may find it more difficult to be sure of the diagnosis.

The examination is carried out in the x-ray department and is performed under local anaesthetic. It is undertaken by a Radiologist (x-ray doctor) or an Advanced
Practitioner (AP) Radiographer and is assisted by a Radiographer and sometimes a Radiographic Assistant. On occasions there are also students in training present, if you agree. Our staff will introduce themselves to you.

Please advise the doctor/AP if you are on any anticoagulation or antiplatelet medication. It is also necessary to highlight any liver or renal failure as well as
any personal or family history of unexplained bleeding.


A Doctor/AP will explain how the LP is performed and you will be given the opportunity to ask questions. Before giving your consent to proceed, the doctor/AP will explain the routine of the procedure, inform you of any possible complications and answer ask any questions you may have. You can at any time refuse to have the LP done for any reason. However, the doctor/AP will need to discuss with you the implications of taking this decision.
There are no special preparations before the procedure. Take all your usual medication. It is sensible to have a light breakfast and is advisable to drink more fluids than usual in the 12 hrs before the examination to reduce the risk of headache. After the examination also you are also advised to drink more than usual to reduce the risk of headache.

What happens

  • The Doctor/AP will usually position you on your left side with your knees curled up to your stomach.
  • The skin of your lower back will be cleaned with an antiseptic—please state if you are allergic to Chlorhexidine. The antiseptic feels wet and cold. A local anaesthetic is then used to numb the skin.
  • You may feel a stinging sensation before the local anaesthetic begins to work. You may then feel a pushing sensation as the needle is inserted, and sometimes a brief, sharp pain when the needle is moved forward. This pain should stop in a few seconds.
  • Overall, discomfort is minimal to moderate but it is important to lie still. Once the needle is correctly positioned, the doctor/AP will measure the pressure (if
    required) and collect samples that are sent off to the lab for testing.
  • The entire procedure usually takes about 30-60 minutes.


Unfortunately, there are no alternatives to obtain CSF samples currently.


  • Back pain at the time of the injection 10%
  • Headache 8-20% -can be helped by drinking lots of fluids and lying down
  • Swelling and bruising
  • Persisting back pain
  • Tingling and numbness in legs – rare
  • Hearing loss/double vision – very rare
  • Loss of power in the limbs less than 1 in 1000
  • Spinal haematoma – extremely rare
  • Bleed inside the head – extremely rare


Following the lumbar puncture you may sit up and have something to drink. You should take things easily for a couple of days and drink more fluids than usual for 24 - 48 hours. You are usually free to leave the ward after a few hours when ward staff have assessed you.


Your results will be discussed at a clinic appointment with your consultant within three to four weeks. If you do not hear within this time frame please contact the consultant’s secretary through the hospital switchboard on 0151-529-3611.

Should you need any further medical help after returning home please call NHS 111/your GP/emergency dept of your local hospital.

  • Last Updated:
    01 October 2019
  • Review Date:
    02 October 2023
  • Author:
    P Crosthwaite
  • Summary:

    A lumbar puncture (LP) is a procedure used to obtain a sample of cerebrospinal fluid (CSF). CSF testing can provide your doctors with information about how the brain and spinal cord is working.

  • Related Service:

Related content