Estimated blood loss underestimates calculated blood loss during radical retropubic prostatectomy.

Objective: To compare the calculated blood loss for radical retropubic prostatectomy (RRP) with the anesthesiologist's and operating surgeon's estimates of operative blood loss.

Methods: A retrospective review of 52 consecutive patients undergoing RRP between January 1999 and February 2000 was performed. Patient charts were reviewed for preoperative hemoglobin (Hgb(i)), preoperative hematocrit (Hct(i)), body weight (Wt), anesthesiologist's and surgeon's estimated blood loss (EBL(A) and EBL(S)), and postoperative day one morning hemoglobin (Hgb(f)) and hematocrit (Hct(f)). For each patient, the actual blood loss (ABL), i.e., the amount of blood that left the patient's body, was calculated as the average ABL(n) resulting from two computations of the following formula: ABL(n) = (EBV x (H(i) - H(f)) / ((H(i) + H(f))/2) + (500 x T(u)) where: (1) estimated blood volume (EBV) is assumed to be 70 cm(3)/kg; (2) H(i) and H(f) represent Hgb(i )and Hgb(f) for one computation and Hct(i) and Hct(f) for the second computation, and (3) T(u) is the sum of autologous whole blood (AWB), packed red blood cells (PRBC), and cell saver (CS) units transfused. For each patient, ABL was compared with EBL(A) and EBL(S). Descriptive statistics of the pooled data were calculated.

Results: The mean (+/- SD) age was 60 +/- 7.1 years. The mean ABL was 2,774 +/- 1,014 cm(3). Patients received an average of 1.96 U CS, 0.14 U PRBC, and 0.42 U AWB. Five patients (9.6%) were exposed to homologous blood. The average ABL(net) (i.e. ABL reduced by the amount of CS returned) was 1,794 +/- 806 cm(3). EBL(A) and EBL(S) were 1,337 +/- 676 and 1,300 +/- 658 cm(3), respectively.

Conclusion: During radical retropubic prostatectomy, anesthesiologists and urologists both appear to underestimate blood loss as determined by standard calculation.