Context: Traumatic or bloody lumbar puncture (LP) reduces the diagnostic value of the procedure and may worsen the outcome of patients with acute lymphoblastic leukemia (ALL). Little is known about the risk factors for traumatic and bloody LP.
Objectives: To determine the risk factors for traumatic and bloody LP.
Design, setting, and patients: Retrospective cohort study of 956 consecutive patients with newly diagnosed childhood ALL who were treated at a pediatric cancer center between February 1984 and July 1998.
Interventions: All patients underwent a diagnostic LP followed by a median of 4 LPs to instill intrathecal chemotherapy.
Main outcome measure: Traumatic LP was defined as an LP in which cerebrospinal fluid contained at least 10 red blood cells (RBCs) per microliter and bloody LP as one in which the cerebrospinal fluid contained at least 500 RBCs per microliter.
Results: Of the 5609 LPs evaluated, 1643 (29%) were traumatic and 581 (10%) were bloody. The estimated odds ratios (ORs) and 95% confidence intervals (CIs) for traumatic LP were 1.5 (95% CI, 1.2-1.8) for black vs white race, 2.3 (95% CI, 1.7-3.0) for age younger than 1 year vs 1 year or older, 1.4 (95% CI, 1.2-1.7) for early vs recent (dedicated procedure area and general anesthesia) treatment era, 1.5 (95% CI, 1.2-1.8) for platelet count of 100 x 10(3)/ microL or more vs less than 100 x 10(3 )/ microL, 10.8 (95% CI, 7.7-15.2) for short (1 day) vs longer (>15 days) interval since the previous LP, and 1.4 (95% CI, 1.1-1.8) for the least vs the most experienced practitioners. Analyses for bloody LP yielded similar results.
Conclusions: The unmodifiable risk factors for traumatic and bloody LP include black race, age younger than 1 year, a traumatic or bloody previous LP performed within the past 2 weeks, and a previous LP performed when the platelet count was 50 x 10(3)/ microL or less. Modifiable risk factors include procedural factors reflected in treatment era, platelet count of 100 x 10(3)/ microL or less, an interval of 15 days or less between LPs, and a less experienced practitioner.