title: Platelet-dense granule deficiency causes postoperative hemorrhage in patients receiving enoxaparin: a novel observation with dramatic clinical implications.
abstract: BACKGROUND
  Inherent hemorrhage risk has impeded the universal adoption of low-molecular-weight heparin (LMWH) for venous thromboembolic prophylaxis in surgical patients. Coagulation pathway parameters and platelet numbers routinely are evaluated preoperatively; scant attention has been directed toward evaluation of platelet function. We hypothesized that administration of LMWH may unmask latent platelet dysfunction and result in postoperative hemorrhage.
  
  
  METHODS
  Postoperative hemorrhage occurred in 15 (3.5%) of 423 consecutive patients undergoing laparoscopic gastric bypass. All patients received LMWH (enoxaparin, 40 mg) preoperatively. Hematologic evaluation included measurement of von Willebrand's factor level and activity, factor VIII level, and electron microscopic enumeration of platelet-dense granules.
  
  
  RESULTS
  All patients had normal preoperative platelet counts and coagulation profiles. Ten patients underwent hematologic evaluation: coagulation pathway parameters were normal in all; however, all patients had a markedly decreased number of platelet-dense granules.
  
  
  CONCLUSIONS
  Platelet-dense granule deficiency may cause postoperative hemorrhage in patients receiving LMWH.
authors.affiliation: Department of Surgery, University of Maryland, Baltimore, MD 21201-1595, USA. mkligman@smail.umaryland.edu
authors.forename: Mark D
authors.initials: MD
authors.lastname: Kligman
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Zyromski
authors.forename: Daniel G
authors.initials: DG
authors.lastname: McCullough
authors.forename: William T
authors.initials: WT
authors.lastname: Gunning
mesh_terms: D000328:Adult; D000925:Anticoagulants / Q000009:adverse effects*; D001791:Blood Platelet Disorders / Q000139:chemically induced*; D003594:Cytoplasmic Granules; D017984:Enoxaparin / Q000009:adverse effects*; D015390:Gastric Bypass; D006801:Humans; D010535:Laparoscopy; D008297:Male; D008875:Middle Aged; D019106:Postoperative Hemorrhage / Q000139:chemically induced*; D012189:Retrospective Studies; D020246:Venous Thrombosis / Q000517:prevention & control
chemical_list: D000925:Anticoagulants; D017984:Enoxaparin