Performance of a new needle system for lumbar punctures in children with blood cancer (leukemia)

INTERVENTION: Patients' lumbar puncture procedures are alternately performed either with the IQ‐Tip system (study arm A) or the conventional spinal needle (study arm B). The maximum number of procedures per patient is four and the method of the first procedure is randomly assigned yielding two possible sequences (either ABAB or BABA) CONDITION: Diagnostics and intrathecal treatment of pediatric patients with leukemia ; Not Applicable PRIMARY OUTCOME: Incidence of traumatic lumbar puncture measured as the proportion of traumatic lumbar punctures (threshold >/= 10 erythrocytes/µl in a cerebrospinal fluid sample) out of all lumbar puncture procedures performed in the given arm after the data collection of the study is completed SECONDARY OUTCOME: 1. First puncture success rate measured as the proportion of successful lumbar puncture procedures at the first attempt (one skin penetration) out of all lumbar puncture procedures performed in the given arm after the data collection of the study is completed; 2. Incidence of post‐dural puncture headache (PDPH) measured as the proportion of lumbar puncture procedures with subsequent PDPH out of all lumbar puncture procedures performed in the given arm after the data collection of the study is completed INCLUSION CRITERIA: 1. Aged between 1 and 18 years old at the beginning of the study 2. Diagnosis or treatment plan requires multiple lumbar puncture procedures for collecting cerebrospinal fluid samples and injecting intrathecal therapy 3. Planned lumbar puncture procedures will be performed with 22G Quincke‐type spinal needles 4. At least two lumbar puncture procedures left in the patient’s treatment protocol 5. Both the parent(s) and the patient, depending on the patient’s age, give a signed informed consent before the first study lumbar puncture procedure