["The presence of a family member during invasive pediatric procedures such as lumbar puncture has been shown to reduce patient anxiety. However, family presence might also affect clinicians' stress and anxiety, with uncertain consequences for procedural success.", 'Our goal was to evaluate the association between family-member presence and lumbar puncture success rates.', 'We performed a prospective cohort study of all children who underwent a lumbar puncture in a single pediatric emergency department between July 2003 and January 2005. The presence of a family member was documented by the physician who performed the lumbar puncture. Success rates were assessed by using 2 main outcomes: (1) the rate of traumatic (cerebrospinal fluid red blood cells > or = 10,000 cells per microL) or unsuccessful lumbar puncture (no cerebrospinal fluid sent for cell counts) and (2) the number of lumbar puncture attempts. Multivariate analyses were adjusted for patient age, race, time of day, physician experience, use of local anesthetic, catheter stylet removal, and patient movement during the procedure.', 'Of the 1474 eligible lumbar punctures, 1459 (99%) were included in the analysis. A family member was present for 1178 (81%) of the procedures studied. A total of 1267 (87%) lumbar punctures were nontraumatic, and 192 (13%) were traumatic or unsuccessful. Neither the rate of traumatic or unobtainable lumbar punctures nor the number of lumbar puncture attempts differed based on whether a family member was present for the procedure.'] Is lumbar puncture success rate influenced by family-member presence?