title: Hidden blood loss and its influential factors after total hip arthroplasty.
abstract: BACKGROUND
  Total hip arthroplasty (THA) is a vital therapy for various hip joint diseases. However, patients have lower hemoglobin level post-operatively, remarkably inconsistent with the measured blood loss. The inconsistence is majorly attributed to hidden blood loss (HBL). In this study, we investigated the HBL and its influential factors among patients after THA.
  
  
  METHODS
  From January 2008 to June 2014, 322 patients (99 males and 223 females) undergoing THA were enrolled in this study. All patients were assessed comprehensively before the operation. The demographic information of the patients was collected. Intra-operative and post-operative blood loss was recorded, and then, the total perioperative blood loss and the HBL were calculated. Influential factors were further analyzed by multiple and stepwise regression.
  
  
  RESULTS
  The HBL was 429 ± 223 mL, with a percentage of 35.4% ± 11.0% in the total perioperative blood loss (1,155 ± 377 mL). Multiple and stepwise regression analysis revealed that HBL was positively associated with body mass index (BMI), blood transfusion volume, length of incision, change of hematocrit (HCT) between pre-operation and post-operation but negatively associated with age. As compared to male patients, female patients had a risk of increased HBL. Development displasia hip (DDH) patients had a less risk of HBL in all patients.
  
  
  CONCLUSIONS
  HBL is a significant portion of total blood loss in the patients after THA. Gender, age, BMI, blood transfusion, length of incision, change of HCT, and diagnosis are influential factors of HBL.
authors.affiliation: Department of Orthopaedics, Changzhou No.2 People's Hospital, the Affiliated Hospital of Nanjing Medical University, 29 Xinglong Alley, Changzhou, 213003, People's Republic of China. miaokaisong@163.com.|Laboratory of Clinical Orthopaedics, Department of Orthopaedics, Changzhou No.2 People's Hospital, the Affiliated Hospital of Nanjing Medical University, 29 Xinglong Alley, Changzhou, 213003, People's Republic of China. miaokaisong@163.com.
authors.forename: Kaisong
authors.initials: K
authors.lastname: Miao
authors.affiliation: Department of Orthopaedics, Changzhou No.2 People's Hospital, the Affiliated Hospital of Nanjing Medical University, 29 Xinglong Alley, Changzhou, 213003, People's Republic of China. vivian.nisu@gmail.com.|Laboratory of Clinical Orthopaedics, Department of Orthopaedics, Changzhou No.2 People's Hospital, the Affiliated Hospital of Nanjing Medical University, 29 Xinglong Alley, Changzhou, 213003, People's Republic of China. vivian.nisu@gmail.com.
authors.forename: Su
authors.initials: S
authors.lastname: Ni
authors.affiliation: Laboratory of Neurological Diseases, Department of Neurology, Changzhou No.2 People's Hospital, the Affiliated Hospital of Nanjing Medical University, 29 Xinglong Alley, Changzhou, 213003, People's Republic of China. hippocampus2007@gmail.com.
authors.forename: Xianju
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Orthopaedics, Changzhou No.2 People's Hospital, the Affiliated Hospital of Nanjing Medical University, 29 Xinglong Alley, Changzhou, 213003, People's Republic of China. xunanwei1963@aliyun.com.
authors.forename: Nanwei
authors.initials: N
authors.lastname: Xu
authors.affiliation: Department of Orthopaedics, Changzhou No.2 People's Hospital, the Affiliated Hospital of Nanjing Medical University, 29 Xinglong Alley, Changzhou, 213003, People's Republic of China. 275585025@qq.com.
authors.forename: Rongbin
authors.initials: R
authors.lastname: Sun
authors.affiliation: Department of Orthopaedics, Changzhou No.2 People's Hospital, the Affiliated Hospital of Nanjing Medical University, 29 Xinglong Alley, Changzhou, 213003, People's Republic of China. zhuangchao911@163.com.
authors.forename: Chao
authors.initials: C
authors.lastname: Zhuang
authors.affiliation: Department of Orthopaedics, Changzhou No.2 People's Hospital, the Affiliated Hospital of Nanjing Medical University, 29 Xinglong Alley, Changzhou, 213003, People's Republic of China. yujiwang@sohu.com.|Laboratory of Clinical Orthopaedics, Department of Orthopaedics, Changzhou No.2 People's Hospital, the Affiliated Hospital of Nanjing Medical University, 29 Xinglong Alley, Changzhou, 213003, People's Republic of China. yujiwang@sohu.com.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000706:statistics & numerical data; D016063:Blood Loss, Surgical / Q000706:statistics & numerical data*; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019106:Postoperative Hemorrhage / Q000453:epidemiology*; D012189:Retrospective Studies