title: Natural course of asymptomatic deep venous thrombosis in hip surgery without pharmacologic thromboprophylaxis in an Asian population.
abstract: BACKGROUND
  The clinical importance of asymptomatic deep venous thrombosis in elective hip surgery is not clearly known.
  
  
  OBJECTIVE
  We determined the preoperative and postoperative incidences of asymptomatic deep venous thrombosis, identified preoperative factors associated with postoperative deep venous thrombosis or pulmonary embolism, and established its natural course in patients who underwent elective hip surgery without receiving pharmacologic thromboprophylaxis.
  
  
  METHODS
  We reviewed 184 patients who underwent consecutive elective hip surgeries with a mechanical thromboprophylaxis regimen including combined general and epidural anesthesia, intraoperative calf bandaging, early mobilization, and postoperative intermittent pneumatic compression with additional use of elastic stockings. Duplex ultrasonography was performed routinely to diagnose deep venous thrombosis in all patients before surgery and on Postoperative Days 3 and 21. All patients with postoperative deep venous thrombosis underwent additional ultrasonography at 3-month intervals, and all patients were followed postoperatively for 6 months or more.
  
  
  RESULTS
  Preoperatively, we found asymptomatic deep venous thrombosis in two patients (1%); both thromboses had completely and spontaneously resolved by Postoperative Day 21. Postoperatively, no patients had a fatal or symptomatic pulmonary embolism or proximal deep venous thrombosis, but nine patients (5%) had asymptomatic distal deep venous thrombosis develop, with no preoperative associated factors. These nine patients were followed closely without anticoagulant drugs, and all thromboses had disappeared without pulmonary embolism or thrombophlebitis by 6 months.
  
  
  CONCLUSIONS
  The incidence of preoperative and postoperative deep venous thrombosis was low in an Asian population having elective hip surgery and a nonpharmacologic thromboprophylaxis regimen. There were no preoperative factors associated with postoperative deep venous thrombosis, and all asymptomatic deep venous thromboses resolved spontaneously without associated pulmonary embolism or thrombophlebitis.
  
  
  METHODS
  Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Tsuda
authors.forename: Tomio
authors.initials: T
authors.lastname: Kawasaki
authors.forename: Nobuo
authors.initials: N
authors.lastname: Nakamura
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Sugano
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D044466:Asian People; D017558:Elective Surgical Procedures; D005260:Female; D006621:Hip Joint / Q000601:surgery*; D006801:Humans; D015994:Incidence; D007564:Japan; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000009:adverse effects*; D012075:Remission, Spontaneous; D012086:Reoperation; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D018616:Ultrasonography, Doppler, Duplex; D020246:Venous Thrombosis / Q000000981:diagnostic imaging / Q000208:ethnology / Q000209:etiology*; D055815:Young Adult