# Lumbar Puncture- Adult

# Overview

This module describes how to collect a sample of cerebrospinal fluid (CSF) from the subarachnoid space.

# Indications

1. Diagnostic:

   1. Suspected CNS infection such as meningitis
   2. Suspected subarachnoid haemorrhage
   3. Suspected CNS disease such as multiple sclerosis

2. Therapeutic: relieving raised intracranial pressure due to

   1. ​​Cryptococcal meningitis
   2. TB meningitis
   3. Benign intracranial hypertension

3. Therapeutic: injecting medication

   1. Spinal anaesthesia
   2. Certain chemotherapy agents
   3. Certain antibiotics

# Contraindications

1. Raised intracranial pressure
   Raised intracranial pressure

   Patients with focal neurological signs, altered levels of consciousness, or papilloedema are at risk of cerebral herniation. Do a CT scan before attempting LP.

   with risk of cerebral herniation

2. Uncorrected coagulopathy such as haemophilia; INR > 1.5; DIC; platelet count < 50

3. Local infection, anatomical distortion or previous surgery at the puncture site

# Patient Information & Consent

Always verify your patient’s identity and obtain informed consent before proceeding.

### How do I explain this procedure?

“I need to put a thin needle into your back to collect fluid from around your spine for testing. The needle will not go into the nerves or spinal cord itself.”

### What can my patient expect?

“You will be awake, but I will inject the area to make it numb. When the feeling returns later on, it may feel tender. You may have a headache or backache for a day or two afterwards. This is usually not serious. The test results can sometimes take several days.”

### What is my patient’s role?

“Let me know if you have any allergies, have had back surgery, have a bleeding tendency, or use blood thinners. Fearing blood or needles is normal, but tell me if you have fainted from it. Help me by bending over forwards, and by staying still. If you feel strange sensations or pain during or some time after the procedure, let us know.”

# Preparation

Ask for an

assistant

assistant

Insist on an assistant as this procedure has many potential risks if performed alone.

. Prepare a trolley with equipment.

### Documentation

1. Laboratory request forms

2. Patient notes

3. Patient labels

### Equipment

1. Sterile gloves

2. Skin disinfectant
   Skin disinfectant

   Commonly used preparations include 0.5-2% chlorhexidine in 70% alcohol (Steriprep), or 10% povidone iodine. There is no consensus on the superiority of one agent above another. Caution: chlorhexidine solutions may be associated with burns and skin breakdown in infants < 2 months old.

3. Sharps container
   Sharps container

   If a sharps container is not within arm's length, use a kidney dish or other hard container to temporarily hold used sharps and to carry them to the sharps container for disposal.

4. Sterile pack

5. Lignocaine for anaesthesia

6. Alcohol swab

7. 3-5 ml syringe

8. One aspiration needle (ideally blunt fill) and one injection needle

9. Spinal needle
   Spinal needle

   If possible, use atraumatic (pencil point) spinal needles, such as the Sprotte and Whitacre needles, rather than than a cutting needle (Quincke), and smaller needle gauges to reduce the incidence of post-dural puncture headache.

1. CSF

   collection tubes
   collection tubes

   Collect specimens in the following order: culture, cell count, chemistry, then glucose. If sterile tubes are used, remember to place them on the sterile field.

   numbered in order

2. Dry gauze and a transparent film dressing (Tegaderm or Opsite)

3. Specimen bag

4. If measuring

   opening and closing pressures
   opening and closing pressures

   Use manometers for ICP measurement only if used at your institution. While the referenced literature still advocates its use, manometers are not widely available. Measuring ICP by lumbar puncture will only reflect an instantaneous value, of which the clinical usefulness is controversial anyway.

   :

   1. Manometer and 2 three-way taps

# Site & Positioning

Position the patient sitting upright or

lying on their side

lying on their side

On their left side if you are right-handed, or on their right side if you are left-handed.

, as close to your edge of the bed as possible. The patient should arch their back as much as possible, and may hold a pillow to assist with positioning. For measuring opening pressure, the patient must be in the lateral position.

The puncture site is in the midline of the spine, between the L4 and L5 vertebrae. This site is best identified with the patient sitting upright. Expose the patient’s back. Palpate with the fingers of both hands the highest points of the iliac crests, and use your thumbs in a straight line from these points to palpate the L4/L5 space. You may use a thumbnail to mark this space on the skin. If the L4/L5 space does not yield CSF, the L3/L4 space (one vertebra higher) may be used. This is why an area covering both spaces should be anaesthetised.

# Procedure

Follow medical asepsis with sterile gloves.

1. Perform hand hygiene.

2. Open the sterile pack and create a sterile field.

3. Open and drop onto the field: needles, syringe, manometer & taps, dressing, and any sterile collection tubes. Fill the well or bowl with skin disinfectant.

4. Place beside the field: sterile gloves, lignocaine, alcohol swab, any non-sterile collection tubes, and specimen bag.

5. Don sterile gloves.

6. Attach the three-way tap to the manometer, loosen the tap, and set it back on the field.

7. Clean
   Clean

   Use cotton balls soaked in skin disinfectant to clean the puncture site and surrounding area, covering at least 3 intervertebral spaces. Start in the middle and clean outwards in circular motions. Allow to dry.

   the site.

8. Drape the area with sterile sheets.

9. Draw up 2-3 ml lignocaine. An

   assistant
   assistant

   If no assistant, see Troubleshooting.

   should clean the top of the lignocaine with an alcohol swab and hold it for you to draw it up.

10. Anaesthetise
    Anaesthetise

    Insert the needle at the puncture site (you may need to repalpate it; this is okay). Withdraw the plunger slightly, checking for blood. Inject lignocaine while withdrawing the needle slightly until just under the surface. Repeat this several times, advancing the needle under the skin to different areas until a circular area around the puncture site is anaesthetised. This area should include the intervertebral spaces above and below the puncture site.

    the area.

11. Uncap the spinal needle and

    insert
    insert

    Bevel facing the patient’s side, holding the needle at the skin with the non-dominant hand. The needle should be in the midline and directed slightly upwards to the patient’s umbilicus.

    it into the L4/5 space. Advance until you feel a “pop” sensation (this may be very subtle), or until 50-75% of the needle is buried.

12. Remove the stylet and wait for CSF to appear in the hub of the needle. Note the

    appearance
    appearance

    Note colour and if it is clear or not.

    of the CSF.

13. Measure opening pressure
    Measure opening pressure

    Ask patient to straighten their neck and legs, and breathe evenly. Connect the manometer to the needle using the three-way tap. Open the tap and read the opening pressure.

    if required.

14. Collect specimens
    Collect specimens

    Pick up each collection tube in turn. Turn the three-way tap to drain CSF from the manometer into each tube (10 drops), and once the manometer is empty, turn the tap to drain CSF from the spine into the tube.

    . Your assistant may open, hand over, and close tubes for you. After touching an unsterile tube, that hand becomes unsterile.

15. If therapeutic tap: drain CSF and measure closing pressure as for opening pressure, ensuring it is now normal.

16. Disconnect the manometer and three-way tap. Replace the stylet and remove the spinal needle in a swift motion. Discard needle in sharps bin.

17. Dress the puncture site with gauze and

    transparent film dressing
    transparent film dressing

    Easier to see local infection or haematoma

    .

18. Dispose of medical waste safely.

19. Place specimens with laboratory request form in specimen bag and send to the lab. Document the procedure in patient notes. Prescribe simple analgesia as required.

20. Check results .

# Troubleshooting

There is no assistant available.

Before opening the sterile pack and donning sterile gloves, don non-sterile gloves, draw up the lignocaine, clean the puncture site with an alcohol swab, and anaesthetise it as a non-sterile procedure. Discard the medical waste safely. You may now open the pack, create a sterile field and continue with the procedure. Alternatively, tape the lignocaine bottle upside-down to an IV pole and clean the cap before getting sterile. That way you can draw up while sterile without compromising sterility.

I’ve hit something hard while advancing the needle.

It’s not uncommon to hit a vertebra. Withdraw the needle to the skin surface and advance it again, using a different angle. Never move the needle without the stylet in place. Try angling more towards the head.

I felt a pop but there is no CSF draining.

This is a “dry tap”. Either the patient is very dehydrated, or you’re not in the right space.

1. Rotate the bevel and look for CSF in the hub.

2. Replace the stylet. Advance 1-2 mm. Repeat until CSF observed.

3. If still no CSF, check that you are in the midline, with the needle aimed towards the umbilicus. If still no CSF, try again using a

   new needle
   new needle

   Call an assistant to open the needle onto the sterile field for you.

   , and the L3/4 space.

The CSF is blood-stained.

This is a “bloody tap”.

1. Rotate the bevel 45° and wait to see if the fluid clears.

2. If not, reinsert the stylet and wait a few minutes. Remove the stylet and check again.

3. If still bloody, remove the needle and try again using a

   new needle
   new needle

   Call an assistant to open the needle onto the sterile field for you.

   and the L3/4 space.

Patient is complaining of pain or paraesthesia.

You are most likely aiming laterally. Ask the patient which leg hurts. Retract to the skin with the stylet in place and reinsert the needle, angled slightly away from the painful leg. If this does not resolve the pain, remove the needle completely and try again using a

new needle

new needle

Call an assistant to open the needle onto the sterile field for you.

and the L3/4 space.

The patient is obese.

Use a longer spinal needle if available. If morbidly obese, an experienced clinician may perform the lumbar puncture using ultrasound guidance.

I don’t have a manometer.

Open an IV line onto the sterile field and attach to the 3 way tap instead of the manometer using the same technique. An assistant may measure CSF height (keeping the IV line upright) with a measuring tape. This method consistently underestimates the pressure. The upper limit of normal, 25 cm using a manometer, measures as 19 cm using the giving set method.

The CSF is coming out very slowly.

Don’t ever aspirate the CSF with a syringe. Ask the patient to cough or strain. Turn the needle 45°, or simply wait.

# Risks

1. Bleeding, bruising, and pain at the site

2. Post dural puncture headache
   Post dural puncture headache

   Occurs in 1/3 of patients, and usually resolves in 10 days. Routine bedrest after LP does not reduce the risk of headache. If it develops, bedrest, hydration, and simple analgesia are the conservative treatment.

3. Infection: cellulitis, meningitis, or epidural empyemas

4. Spinal nerve damage

5. Brain herniation into the foramen magnum
   Brain herniation into the foramen magnum

   In patients with signs of raised intracranial pressure with herniation risk (altered state of consciousness, focal neurological deficits, or papilloedema), do a head CT first.

6. Spinal canal haematoma
   Spinal canal haematoma

   Rare in patients without coagulopathy

   with spinal cord compromise

7. Intraspinal epidermoid tumours
   Intraspinal epidermoid tumours

   Fragments of skin carried into the spinal canal form tumours that cause local pain or neurological findings in the legs months after the procedure.

# References

1. Schneider VF. In: Dehn R, Asprey D, eds. Essential Clinical Procedures. 3rd ed. Philadelphia: Elsevier; 2013.

2. Doherty CM & Forbes RB. Diagnostic Lumbar Puncture. The Ulster Medical Journal. 2014;83(2):93–102.

3. Naidoo C, Ross A. How to perform a lumbar puncture in an adult. In: Mash B, Blitz-Lindeque J, eds. South African Family Practice Manual. 2nd ed. Pretoria: Van Schaik Publishers; 2010: 331-332.

4. Henning P.Lumbar Puncture. In Neonatology: A guide for doctors. Department of Paediatrics and Child Health and Stellenbosch University. Tygerberg Hospital South Africa. 2012. p. 160-161

5. Joolay Y, Horn A, et al.Lumbar Puncture. In: Neonatal Guidelines and Drug Dosages. Division of Neonatal Medicine Groote Schuur Hospital. 2012. p. 135