Lumbar Puncture (LP) in Newborn Babies with a Suspected Infection
Tel: 01206 746208 or 746209
Children’s Assessment Unit
Tel: 01206 746200
Tel: 01206 742857
What is a lumbar puncture?
A lumbar puncture (LP) is a procedure performed by a doctor or advanced neonatal nurse practitioner (ANNP). It involves taking a very small sample of fluid from the lumbar region in the lower back, by using a small fine hollow needle. A lumbar puncture is also known as an LP.
The fluid taken during an LP is cerebrospinal fluid (CSF). CSF surrounds the brain and spinal cord, providing the brain with nutrients. Because of its close association with the brain and the brain’s protective layers (the meninges), CSF gives very useful information about infections that affect the brain and its protective layers.
LPs may be performed for many reasons. In newborn babies the most common reason is to diagnose or rule out an infection affecting the meninges, called meningitis. Newborn babies are at greater risk of meningitis because their immune systems are still developing.
It is very difficult to diagnose meningitis in newborn babies because they present with non-specific symptoms which could reflect many other illnesses and infections. It is very important not to miss a diagnosis of meningitis and for this reason LPs are commonly performed on newborn babies. Most LP results confirm that the baby does not have meningitis but if evidence is found this information can be life-saving.
If your baby has had blood tests and these suggest the presence of infection, it is important to determine if this is meningitis. These blood tests may include blood cultures (growth of bacteria which can cause infection).
A raised C-reactive protein (CRP), which is a protein found in the blood during infections, may also suggest your baby has an infection. At Colchester Hospital, an LP is usually recommended in babies with a CRP reading greater than 15-20.
There are several signs and symptoms suggestive of meningitis that may prompt the need to perform an LP.
- high fevers – newborn babies rarely suffer from significant fevers. If a baby has a temperature greater than 38°C, it could be a sign of meningitis
- bulging fontanelle (the soft spot over baby’s head)
- excessive drowsiness or floppiness
- excessive jerky movements of the arms and legs or increased body stiffness
- the baby is irritable when handled, often with a high pitched cry.
LPs are common procedures and are performed in a controlled fashion, ensuring they are safe and well tolerated by the baby. Serious complications following an LP are extremely rare but like any medical procedure there is a risk of complications. If these occur they are usually mild, with no lasting damage.
Some potential complications include:
- failure to obtain a CF sample is the most common complication. LPs in newborn babies are technically difficult due to the baby’s small size. Repeat attempts may be required. The procedure is usually abandoned after 3-4 failed attempts
- blood-stained CF – a small amount of blood may contaminate the SF sample. This should not affect baby but does make interpretation of the laboratory results more difficult
- pain – as the needle enters the skin there may be some discomfort. Oral sucrose solution may be given, which eases pain and distress in young babies
- headache – this is usually mild and short lasting
- bleeding – there is a small risk of bleeding into the CSF space following an LP. At Colchester Hospital, it is common practice to check a baby’s platelet count (the cells which clot blood to stop bleeding) before performing an LP
- breath holding – during the procedure babies may become distressed, resulting in them holding their breath. If this occurs the baby will be allowed to recover before the procedure continues
- infection – any medical procedure that penetrates the skin risks the introduction of infection. To help prevent this, LPs are performed using sterile equipment and cleaning solutions
- CSF leak – occasionally CSF may leak through the entry site of the needle after the procedure and a small swelling may be visible. A dressing can be applied to help stop this and it should not normally cause any problems for a baby
- damage to vertebrae – very rarely, the needle may damage or introduce infection into one of the bones (vertebrae) of the lower back. The risk is higher in babies requiring multiple LPs over a period of time but even then it happens very rarely.
Many parents worry about the risk of damage to the spinal cord. The spinal cord in babies finishes above the second to third lumbar vertebrae. In order to protect the cord, lumbar punctures are performed in the lower back, below this level, therefore keeping the needle away from the spinal cord.
It is rare to catch a nerve during the procedure. We know that in older children and adults this will usually cause only short-term shooting pain or numbness.
If the pressure of the CSF is raised there is a risk of brain herniation (movement). This is extremely rare in newborn babies but is a serious and potentially fatal condition. Your doctor or advanced neonatal nurse practitioner (ANNP) will avoid performing an LP if your baby shows any signs of raised pressure in the CSF.
LPs are extremely useful – if bacteria are detected in the CSF it is normally possible to determine which antibiotics will work best. In addition, if evidence of meningitis is detected in the CF the doctor or ANNP will know that a longer duration of antibiotics is required, and the risk of sending a baby home following an incomplete course of antibiotics is minimised. Meningitis requires a longer duration of antibiotics than other infections to ensure all the bacteria are killed.
The actual procedure is very quick but the total time your baby will be away from you may be longer, because the doctor or ANNP and nurse will take their time in preparing for the procedure. It is very important that they are able to concentrate fully while performing an LP. For this reason it is hospital policy not to allow parents into the treatment room during the procedure.
Before the procedure the nurse will check your baby’s blood sugar level so it can be compared with the sugar level in the CSF. Your baby will then be given oral sucrose to help ease any distress.
The nurse will hold your baby’s shoulders and bottom to keep him or her still and maximise the natural curve of your baby’s back. The doctor or ANNP will then insert the special needle into the space between the spinal bones and collect a very small volume of CSF (20-24 drops).
After the procedure your baby should lay flat in a cot for an hour. Any dressing can be removed after 24 hours.
- Microscopy – a sample is treated with a special stain and examined under a microscope by an expert who looks for bacteria and white cells (which are present in infections).
The results are available within 2-3 hours.
- Glucose /Protein levels – infection may lower CF glucose levels and raise CF protein levels.
- Culture – the SF is monitored in the laboratory to see if bacteria grow. This takes 24-48 hours.
- PCR (a technique for testing DNA in a test tube) – if your doctor or advanced neonatal nurse practitioner (ANNP) suspects a viral illness, the CF may be tested for the virus’s DNA. This is performed only in special circumstances and it can take 10 days before a result is available.
Seek medical help if you notice an unexplained fever or either of the following:
- tender, red swelling at the lumbar puncture site
- clear fluid or blood leaking from site.
Lie the baby flat on his or her back and seek medical help.
The doctor or advanced neonatal nurse practitioner (ANNP) will ask for your consent before performing an LP.
If you do not want your baby to have one or if it is not possible to obtain an adequate CSF sample, your doctor or ANNP will advise on the best alternative treatment. This may involve an extended course of antibiotics with repeat blood tests to monitor your baby’s response.
Your midwife, nurse or doctor / ANNP will be happy to help.
Wristbands are used to identify hospital inpatients. When your baby is in hospital it is essential that he or she is given and wears their wristband, which carries his or her name, date of birth, NHS number and hospital number. This ensures that staff can identify your baby correctly and give them the right care.
When you attend hospital with your baby you will be asked to confirm your baby’s first and last names, date of birth, postcode and NHS number, if you know it, and to let us know if he or she has any allergies.
To find out how to give us feedback on your visit or healthcare experience, please visit www.esneft.nhs.uk and search for ‘PALS’ or ‘Your views matter’, or speak to a member of staff on the ward or department you are in.