title: Hematoma risk after needle electromyography.
abstract: BACKGROUND
  Although needle electromyography (EMG) appears to be a relatively safe procedure based primarily on clinical experience, no evidence-based guidelines exist for EMG procedures in patients taking anticoagulant or antiplatelet medications. We sought to determine whether there is an increased risk of hematoma formation after EMG of potentially high-risk muscles in patients taking anticoagulant or antiplatelet agents.
  
  
  METHODS
  After undergoing routine EMG, if any of seven predetermined high-risk muscles were tested, study subjects then underwent ultrasound to evaluate for hematoma formation.
  
  
  RESULTS
  Patients were divided into three groups based on medication (warfarin, aspirin/clopidogrel, no blood-thinning medication), with at least 100 muscles examined per group. Two small, subclinical hematomas were seen on ultrasound; there was no difference in hematoma risk between groups (P = 0.43).
  
  
  CONCLUSIONS
  Our findings suggest that hematoma formation from standard needle EMG is rare even in high-risk muscles, which have been avoided historically in anticoagulated patients.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA. boon.andrea@mayo.edu
authors.forename: Andrea J
authors.initials: AJ
authors.lastname: Boon
authors.forename: Jon T
authors.initials: JT
authors.lastname: Gertken
authors.forename: James C
authors.initials: JC
authors.lastname: Watson
authors.forename: Ruple S
authors.initials: RS
authors.lastname: Laughlin
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Strommen
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Mauermann
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Sorenson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage; D016022:Case-Control Studies; D000077144:Clopidogrel; D004576:Electromyography / Q000009:adverse effects*; D005260:Female; D006406:Hematoma / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009135:Muscular Diseases / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology*; D009339:Needles / Q000009:adverse effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage; D011446:Prospective Studies; D012307:Risk Factors; D013988:Ticlopidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D018608:Ultrasonography, Doppler; D014859:Warfarin / Q000008:administration & dosage; D055815:Young Adult
chemical_list: D000925:Anticoagulants; D010975:Platelet Aggregation Inhibitors; D014859:Warfarin; D000077144:Clopidogrel; D013988:Ticlopidine