intraoperative blood loss is one the most commonly used parameters to assess the safety of surgical procedures .
available data regarding laparoscopic radical prostatectomy ( lrp ) indicates unambiguously that the surgery is safe , also in terms of blood loss [ 1 , 2 ] .
what is more , reduced blood loss remains one of crucial advantage of lrp when compared with open radical prostatectomy [ 3 , 4 , 5 ] .
many investigators confirmed all facts mentioned above since 1997 when schuessler performed the first lrp in history .
250 ml is reported in recent studies enrolling a large series of patients . however , traditionally we base blood loss on blood volume collected intraoperatively in the suction device bottles .
we already know that both anesthesiologists and urologists tend to underestimate blood loss during open retropubic prostatectomy and that the underestimation is relatively important . the little accuracy of visual estimation of blood loss had been clearly proven by gynecologists and obstetricians [ 9 , 10 , 11 ] . in this
setting , we decided to answer the question whether intraoperative blood loss during lrp assessed clinically corresponds with changes in blood cell count ( bcc ) .
the aim of this study was to analyze changes in bcc resulting from lrp and to compare them with clinical blood loss estimation .
there were 71 men submitted to extraperitoneal lrp due to organ confined prostate cancer in our institution from september 2009 to march 2011 .
based on a surgeon 's subjective assessment reported in their surgical protocol , we isolated the group of 61 men with clinically minimal intraoperative blood loss , which was defined as loss of less then 200 ml . for the final analysis we included 60 men with full data regarding surgery and laboratory findings in perioperative period . mean age of the cohort was 62.8 years .
we performed retrospective analysis of medical documentation with special interest in laboratory findings . according to standard management with patients submitted to lrp in our institution , all the group had blood tests performed a day before ( test 1 ) and 6 hours after the surgery ( test 2 ) .
we registered results of all bcc parameters , creatinine serum concentration and estimated glomerular filtration rate ( egfr ) at these two time intervals .
an automated hematology analyzer was used for bcc and the colorimetric jaffe reaction for creatinine serum concentration measurement .
estimated gfr was calculated using the mdrd ( modification of diet in renal disease ) formula . paired t - test was used for comparing results of tests 1 and 2 for each parameter .
normal distribution was confirmed by the shapiro - walk test while the equality of variances was assessed using levene 's test before all the t - tests were performed .
the differences were considered to be statistically significant when the p - value was lower than 0.02 .
there were 71 men submitted to extraperitoneal lrp due to organ confined prostate cancer in our institution from september 2009 to march 2011 . based on a surgeon 's subjective assessment reported in their surgical protocol
, we isolated the group of 61 men with clinically minimal intraoperative blood loss , which was defined as loss of less then 200 ml . for the final analysis we included 60 men with full data regarding surgery and laboratory findings in perioperative period . mean age of the cohort was 62.8 years .
we performed retrospective analysis of medical documentation with special interest in laboratory findings . according to standard management with patients submitted to lrp in our institution , all the group had blood tests performed a day before ( test 1 ) and 6 hours after the surgery ( test 2 ) .
we registered results of all bcc parameters , creatinine serum concentration and estimated glomerular filtration rate ( egfr ) at these two time intervals .
an automated hematology analyzer was used for bcc and the colorimetric jaffe reaction for creatinine serum concentration measurement .
estimated gfr was calculated using the mdrd ( modification of diet in renal disease ) formula .
paired t - test was used for comparing results of tests 1 and 2 for each parameter .
normal distribution was confirmed by the shapiro - walk test while the equality of variances was assessed using levene 's test before all the t - tests were performed .
the differences were considered to be statistically significant when the p - value was lower than 0.02 .
we noticed statistically and clinically significant differences regarding all bcc parameters measured at the two time intervals .
the measurement results are expressed as mean values and standard deviations rbc  red blood cells ; hb  hemoglobin concentration ; hct  hematocrit ; wbc  white blood cells ; pct  platelet crit simultaneously , renal function , assessed by creatinine serum concentration measurement and egfr calculation , was stable .
the measurement results are expressed as mean values and standard deviations creat  creatinine serum concentration ; egfr  estimated glomerular filtration rate
our retrospective investigation was aimed at critical analysis of the value of clinical assessment of blood loss during lrp . to the best of our knowledge ,
such an analysis has never been done before , while its clinical importance remains obvious . based on previous studies we can calculate the effect of blood loss on hemoglobin concentration . using the same formulas
taking the results of a study performed by davies et al . , we may assess the real blood loss in our group of patients to be as high as 8 ml / kg , hence 600 ml in a typical 75 kg male prostate cancer patient .
at the same time , clinically assessed blood loss was calculated by the surgeon to be not more than 200 ml .
our study shows discrepancies between clinical estimation and laboratory results using the laparoscopic approach , which occurred to be much more significant . while the differences in open prostate surgery do not exceed 30% , we noticed differences of 300% in our group . finally , it is also worth remembering that laboratory tests are imperfect .
showed that when assessing blood loss based on a decrease in hemoglobin concentration , we can underestimate it by more than 30% .
it means that real blood loss in our group of patients might even exceed 800 ml , hence we found a four - fold clinical underestimation of blood loss .
we can summarize that clinical and laboratory methods of blood loss estimation are neither practical nor reliable .
this important statement is supported by schorn 's critical review of methods of blood loss measurement .
the reason for such important differences between clinical and laboratory estimation of blood loss during lrp should be indicated . in general , bleeding during laparoscopic procedures may be reduced following insufflation of the appropriate cavity and the associated tamponade effect [ 1518 ] . in this
setting , venous bleeding is more likely to occur shortly after the procedure than during the surgery .
we suppose that visual underestimation of blood loss may result from early postoperative formation of perivesical , perineal , or obturator hematomas , while direct measurement of blood loss does not consider it .
first , it is its retrospective character , which is supported by archival medical documentation .
this fact may affect results , however , obtained results are clearly unambiguous . whether we under- or overestimate the significance of the problem
second , being a pilot study , this analysis covers only 60 cases of lrp with clinically minimal blood loss . based on our preliminary results
, it may be justified to collect the data prospectively in order to finally confirm our findings .
the accuracy of clinical estimation of blood loss during lrp is low . while clinically insignificant , blood loss seems to be as high as approx .
bcc seems to be a more accurate method of intraoperative blood loss estimation compared to measurement of blood volume collected intraoperatively in the suction device bottles .
 introductionthe traditional assessment of blood loss during laparoscopic radical prostatectomy ( lrp ) is based on the blood volume collected intraoperatively in the suction device bottles . 
 while this method is not perfect , analysis of changes in blood cell count ( bcc ) resulting from lrp is advisable.material and methods71 men were submitted to lrp due to prostate cancer in our institution over an 18-month time period . from this group 
 , we isolated 60 men with clinically minimal intraoperative blood loss ( < 200 ml ) and included them into the study . 
 mean age of the cohort was 62.8 years . 
 we performed standard bcc on the day before and 6 hours after the surgery . at the same time points , we measured creatinine serum concentration and calculated egfr to avoid the data misinterpretation resulting from impaired renal function in the postoperative period.resultsstatistically and clinically significant differences regarding all bcc parameters measured pre- and postoperatively were observed . the number of red blood cells , hemoglobin concentration , and hematocrit diminished by 17.5% ( 4.68t / 
 l vs. 3.86t / l , p < 0.02 ) , 17.0% ( 8.93 mmol / l vs. 7.41 mmol / l , p < 0.02 ) , and 17.9% ( 0.429 vs. 0.352 , p 
 < 0.02 ) , respectively . 
 simultaneously , renal function was stable with no significant change in egfr ( 82.9 ml / min/1.73 m^2 vs. 79.09 ml / min/1.73 m^2 , p = 0.28).conclusionsstandard lrp brings on a significant blood loss . while clinically insignificant , this blood loss seems to be as high as approx . 
 600 ml based on laboratory findings . 
 bcc seems to be a more accurate method of intraoperative blood loss estimation compared to measurement of blood volume collected intraoperatively in the suction device bottles . 
Introduction
MATERIAL AND METHODS
Population
Intervention
Statistical analysis
Results
DISCUSSION
CONCLUSIONS