Infection may be inadvertently introduced during the procedure. It may be superficial or deep and may be caused by either skin commensals surviving on the patient or respiratory flora from the person performing the lumbar puncture. Deep infection includes the serious complications of meningitis and spinal abscess and will need urgent intravenous antibiotics after discussion with a microbiologist. Spinal abscess causing nerve root compression may need urgent neurosurgical decompression. Adequate disinfection of the skin and the use of surgical face‐masks will reduce the risk to the patient (Chernecky and Berger [32], Doherty and Forbes [50], Schneider [222]).

Haemorrhage or localized bruising may be caused by a traumatic procedure or in the presence of thrombocytopenia or a coagulopathy (Barker and Laia [10], Lindsay et al. [126]). Haematoma formation may become a surgical emergency if there is nerve root compression.

Transtentorial or tonsillar herniation is possible if lumbar puncture is carried out in the presence of raised ICP (Doherty and Forbes [50]). This is a serious and life‐threatening complication and so brain imaging studies should be done if raised ICP is suspected. Consultation with a neurologist may also be warranted.

Frequency of PLPH varies among studies and between diagnostic and therapeutic procedures. Most symptoms develop within 24 hours. The following risk factors have been identified: young age, female gender and the presence of headache before or at the time of the lumbar puncture (Chernecky and Berger [32], Doherty and Forbes [50], Engelborghs et al. [56]). In more than 85% of cases, PLPH will resolve without any treatment. Rehydration, pain relief and antiemetic medications can help in milder cases (Doherty and Forbes [50]). If severe or prolonged, the headache may be treated with an epidural blood patch, usually after referral to an anaesthetist (Engelborghs et al. [56], Gruener and Biller [77]).

Backache after lumbar puncture may be due to either local bruising from the lumbar puncture needle or excessive spinal flexion for prolonged periods of time (i.e. during difficult procedures). It does not seem to be affected by different needle sizes or by repeated attempts to gain CSF (Engelborghs et al. [56], Pagana and Pagana [177]). In rare cases, backache may be suggestive of spinal haematoma or abscess, particularly if associated with leg weakness or bladder/bowel disturbance.

There may be a small amount of blood‐stained oozing (Doherty and Forbes [50], Pagana and Pagana [177]). The presence of clear fluid should be reported immediately to the doctor, especially if it is accompanied by fluctuation of other symptoms (e.g. level of consciousness, motor changes, problems voiding), as it may indicate a CSF leak (Barker and Laia [10]).