in patients with bladder outlet obstruction ( boo ) due to benign prostatic hyperplasia ( bph ) , transurethral resection of the prostate ( turp ) has long been considered a standard treatment regimen . in 1995 ,
gilling first introduced holmium laser prostatectomy for the treatment of bph . since then , holmium laser enucleation of the prostate ( holep ) has been increasingly performed .
holep is advantageous in that it can be performed both effectively and safely with no respect to the size of prostate .
as compared with open prostatectomy or turp , holep shows a lower morbidity and a shorter length of hospital stay [ 3 - 5 ] . it is composed a two - stage procedure : enucleation and morcellation . to date , however , most studies have focused on enucleation and its outcomes .
given the above background , we developed an inverse technique for tissue morcellation by modifying the conventional upward technique and then examined its safety and efficiency .
the current study was conducted in 389 patients ( n=389 ) with bph who underwent holep between july 2008 and december 2010 . for tissue morcellation
, we used an upward technique for an initial series of 84 patients during a period from july 2008 to june 2009 and an inverse technique for a consecutive series of the remaining 305 patients between july 2009 and december 2010 . in the current study ,
the inclusion criteria were an international prostate symptom score ( ipss ) of 8 , a peak urinary flow rate ( qmax ) of 15 ml / sec , and significant postvoid residual ( pvr ) urine volume .
in addition , the exclusion criteria were prostate cancer , neurogenic bladder , and urethral surgery .
a prostate biopsy was done , if clinically applicable , to rule out the possibility of prostate cancer .
, all patients underwent a digital rectal examination , serum prostate - specific antigen ( psa ) measurement , transrectal ultrasonography , uroflowmetry , and residual urine measurement and ipss and quality of life ( qol ) scores were determined .
holep was done preferably under spinal anesthesia and was composed of two maneuvers : enucleation of prostate adenoma and morcellation of adenoma tissue within the bladder .
the mechanical morcellator device is constructed of a handpiece and blades ( the outer sheath and inner sheath ) .
the inner sheath aspires the tissue , which is followed by the morcellation of the tissue by a sharp portion between the outer sheath and the inner one .
when surgeons notice that the bladder is sufficiently filled and then remote from the bladder mucosa , they place a resectoscope central to the bladder .
the morcellator contains a two - phase foot pedal . by sharp pressing of the pedal ,
this is followed by the morcellation of the captured tissue by the blades by full pressing of the pedal . with the use of the currently commercially available form of the morcellator , the most important detail is the shape of the tip of the morcellator .
similarly , the inner sheath also has a semi - tubular shape . to prevent the aspiration of the bladder mucosa from the tip of the morcellator
, the morcellator was designed to have a blind - ended tip of the inner sheath . when surgeons discontinue operation of the morcellator , they can adjust the location of the blades .
surgeons should be aware that there is a complete lack of aspiration if they halt the tip of the inner sheath before the holes made in the outer sheath .
the conventional method of tissue morcellation , that is , the upward technique , is operated when the blades are directed upwards and the tissue is first aspirated from their superior part .
, we used an inverse technique , a modified form of the conventional upward technique , for 305 patients excluding an initial series of 84 patients . in the inverse technique ,
the prostate tissue is aspirated and then captured superiorly by inversely placing the blades inferior to the bladder and superior to the prostate tissue ( fig .
the versapulse power suite ( lumenis , yokneam , israel ) holmium laser was used for enucleation of prostatic adenoma at a laser power of 80 to 100 w. in addition , a 26-fr resectoscope ( karl storz , el segundo , ca , usa ) with a laser bridge was used .
the tissue morcellation was performed by using a percutaneous nephrolithotomy nephroscope and a versacut morcellator ( lumenis ) . between the upward technique group and the inverse technique group ,
we compared the mean morcellation time , the morcellation efficiency , the incidence and location of bladder injury occurring during the morcellation , and the catheter time . to rule out the possibility of a learning curve , we excluded an initial series of 20 patients .
then , we divided our clinical series of patients into the upward technique group and three inverse technique groups on the basis of the timing of the inverse technique : group 1 ( early stage ) , group 2 ( middle stage ) , and group 3 ( late stage ) .
in addition , on the basis of a cutoff value of 50 g , we divided our clinical series of patients into two groups : a group with a prostate size of 50 g and a group with a prostate size of < 50 g. then , we compared the mean morcellation time , the morcellation efficiency , the incidence and location of bladder injury occurring during the morcellation , and the catheter time between the two groups .
the mean values of continuous variables were used in the analysis , for which ranges are presented in parentheses .
the unpaired student 's t - test was used to analyze the differences in mean values between the four groups .
in addition , the mann - whitney u test was used to analyze non - normally distributed continuous variables . a p - value of < 0.05 was considered statistically significant .
the current study was conducted in 389 patients ( n=389 ) with bph who underwent holep between july 2008 and december 2010 . for tissue morcellation
, we used an upward technique for an initial series of 84 patients during a period from july 2008 to june 2009 and an inverse technique for a consecutive series of the remaining 305 patients between july 2009 and december 2010 . in the current study ,
the inclusion criteria were an international prostate symptom score ( ipss ) of 8 , a peak urinary flow rate ( qmax ) of 15 ml / sec , and significant postvoid residual ( pvr ) urine volume .
in addition , the exclusion criteria were prostate cancer , neurogenic bladder , and urethral surgery .
a prostate biopsy was done , if clinically applicable , to rule out the possibility of prostate cancer .
, all patients underwent a digital rectal examination , serum prostate - specific antigen ( psa ) measurement , transrectal ultrasonography , uroflowmetry , and residual urine measurement and ipss and quality of life ( qol ) scores were determined .
holep was done preferably under spinal anesthesia and was composed of two maneuvers : enucleation of prostate adenoma and morcellation of adenoma tissue within the bladder .
the mechanical morcellator device is constructed of a handpiece and blades ( the outer sheath and inner sheath ) .
the inner sheath aspires the tissue , which is followed by the morcellation of the tissue by a sharp portion between the outer sheath and the inner one .
first , a resectoscope is replaced with a nephroscope following enucleation . when surgeons notice that the bladder is sufficiently filled and then remote from the bladder mucosa , they place a resectoscope central to the bladder .
the morcellator contains a two - phase foot pedal . by sharp pressing of the pedal ,
this is followed by the morcellation of the captured tissue by the blades by full pressing of the pedal . with the use of the currently commercially available form of the morcellator ,
similarly , the inner sheath also has a semi - tubular shape . to prevent the aspiration of the bladder mucosa from the tip of the morcellator
, the morcellator was designed to have a blind - ended tip of the inner sheath . when surgeons discontinue operation of the morcellator , they can adjust the location of the blades .
surgeons should be aware that there is a complete lack of aspiration if they halt the tip of the inner sheath before the holes made in the outer sheath .
the conventional method of tissue morcellation , that is , the upward technique , is operated when the blades are directed upwards and the tissue is first aspirated from their superior part .
, we used an inverse technique , a modified form of the conventional upward technique , for 305 patients excluding an initial series of 84 patients . in the inverse technique ,
the prostate tissue is aspirated and then captured superiorly by inversely placing the blades inferior to the bladder and superior to the prostate tissue ( fig .
the versapulse power suite ( lumenis , yokneam , israel ) holmium laser was used for enucleation of prostatic adenoma at a laser power of 80 to 100 w. in addition , a 26-fr resectoscope ( karl storz , el segundo , ca , usa ) with a laser bridge was used .
the tissue morcellation was performed by using a percutaneous nephrolithotomy nephroscope and a versacut morcellator ( lumenis ) .
between the upward technique group and the inverse technique group , we compared the mean morcellation time , the morcellation efficiency , the incidence and location of bladder injury occurring during the morcellation , and the catheter time . to rule out the possibility of a learning curve , we excluded an initial series of 20 patients .
then , we divided our clinical series of patients into the upward technique group and three inverse technique groups on the basis of the timing of the inverse technique : group 1 ( early stage ) , group 2 ( middle stage ) , and group 3 ( late stage ) .
in addition , on the basis of a cutoff value of 50 g , we divided our clinical series of patients into two groups : a group with a prostate size of 50 g and a group with a prostate size of < 50 g. then , we compared the mean morcellation time , the morcellation efficiency , the incidence and location of bladder injury occurring during the morcellation , and the catheter time between the two groups .
the mean values of continuous variables were used in the analysis , for which ranges are presented in parentheses .
the unpaired student 's t - test was used to analyze the differences in mean values between the four groups .
in addition , the mann - whitney u test was used to analyze non - normally distributed continuous variables . a p - value of < 0.05 was considered statistically significant .
there were no significant differences in mean age or prostate volume between the two groups .
the mean morcellation time was 14.38.6 minutes in the upward technique group and 6.47.2 minutes in the inverse technique group .
the morcellation efficiency was 1.931.14 g / min and 4.030.89 g / min in the two groups , respectively .
thus , the degree of morcellation efficiency was significantly higher in the inverse technique group ( p<0.05 ) .
there were 11 cases ( 13.1% ) and 4 cases ( 1.3% ) of bladder injury during the morcellation , respectively .
in particular , there were 5 cases ( 5.9% ) and 1 case ( 0.3% ) of severe bladder injury in the corresponding order , for which a urethral catheter was required for more than 3 days postoperatively . that is , the incidence of severe bladder injury was significantly higher in the upward technique group .
regarding the site of bladder injury , 7 cases ( 63.6% ) and 4 cases ( 36.4% ) of bladder injury occurred in the bladder dome and the posterior wall , respectively , in patients in the upward technique group . in the inverse technique group , however , the site of bladder injury was limited to the trigone ( table 2 )
. to rule out the possibility of a learning curve , we excluded an initial series of 20 patients .
then , we divided our clinical series of patients into the upward technique group and three inverse technique groups on the basis of the timing of the inverse technique .
the mean morcellation efficiency was 2.150.82 g / min , 3.950.91 g / min , 3.711.56 g / min , and 3.831.35 g / min in the upward technique group and in groups 1 , 2 , and 3 of the inverse technique group , respectively .
thus , morcellation efficiency was significantly higher in all three inverse technique groups than in the upward technique group .
there was no significant difference in the mean morcellation efficiency between the three inverse technique groups ( table 3 ) .
using the cutoff value of 50 g , we divided our clinical series of patients into two groups : the group with a prostate size of 50 g and that with a prostate size of < 50 g. then , we compared the mean morcellation efficiency between the two groups .
this comparison showed that morcellation efficiency was 2.80.97 g / min in the group with a prostate size of < 50 g and 3.50.75 g / min in the group with a prostate size of 50 g. in addition , there were six cases and nine cases of bladder injury , respectively .
furthermore , the mean morcellation efficiency and the incidence of bladder injury were significantly higher in the group with a prostate size of < 50 g than in the group with a prostate size of 50 g. however , this difference was not statistically significant ( table 4 ) .
recently , it has been increasingly reported that holep can be used as an alternative to the traditional bph surgery .
the holep technique consists of a two - stage procedure : enucleation for removal of adenoma along the surgical capsule and morcellation for the aspiration and removal of the adenoma tissue in the urinary bladder . with the development of a morcellator , it has become possible to perform surgery for patients with large - sized bph .
compared with the traditional treatment regimens for bph , that is , turp and open prostatectomy , holep has been reported to cause lower morbidity and similar or better postoperative outcomes . despite these advantages , the holep procedure has the disadvantage of a learning curve that is not easily overcome .
several studies have reported that time and experience are needed to overcome the learning curve [ 13 - 16 ] . according to
many currently published articles about holep , the upward technique is recommended to aspirate the adenoma superiorly to the blades of a morcellator before the morcellation of adenoma .
this is commonly used in a clinical setting . in this upward technique , it is not actually easy to put the large extracted tissue on the blades with the thin shape of the rod in a narrow visual field
. it is therefore highly probable that this might lead to careless operation of the blades in a place remote from the endoscope in a poor visual field because the blades have a penetrating appearance on the tip of an endoscope .
we have therefore used the inverse technique by inversely rotating both the nephroscope and the blades .
in addition , there is a visual field of the endoscope between the blades and the tissue .
this makes it easier not only to confirm the aspirated tissue but also to minimize unnecessary manipulation to put the tissue on the blades .
this is also accompanied by decreased risks of damaging the bladder mucosa during the morcellation . in the current study , we compared the mean morcellation time , the incidence of bladder injury , and catheter time between the upward technique group and the inverse technique group .
regarding the sites of occurrence of bladder injury , the tissue is aspirated when the blades are directed downward toward the urinary bladder . therefore
this indicates that the inverse technique is relatively safe and has a lower risk of bladder perforation than does the upward technique , which was associated with the occurrence of bladder injury in the bladder dome and the posterior wall ( table 2 ) . unlike enucleation
, it has been reported that the morcellation is not subject to a learning curve .
shah et al . compared the morcellation efficiency in 16 groups ( 10 patients assigned to the first 15 groups each and 12 assigned to the final 16th group ) . but
these authors reported that morcellation efficiency showed no great changes and was not increased with experience .
moreover , seki et al .   also compared the morcellation efficiency in seven groups ( 10 patients assigned to seven groups each ) .
these authors noted that the value of morcellation efficiency was increased but this was not statistically significant .
compared the morcellation efficiency between an initial series of 60 patients ( 20 patients assigned to three groups each ) .
these authors reported that the value of morcellation efficiency was significantly increased by 0.61 g / min , 1.70 g / min , and 2.03 g / min in the corresponding order ( p<0.001 ) .
they also noted that 20 cases were required for the adaptation to the morcellation procedure . in the current study , to rule out the possibility of a morcellation learning curve , we divided our clinical series of patients into four groups that excluded an initial series of 20 patients : the upward technique ( n=64 ) group and three inverse technique groups that were based on the timing of the procedure .
this showed that there was a significant difference in the morcellation efficiency ( p<0.05 ) .
this suggests that a significant difference in the morcellation efficiency between the upward technique group and the three inverse technique groups did not originate from the morcellation learning curve ( table 3 ) .
the morcellation efficiency was significantly higher in the inverse technique group than in the upward technique group .
this was due to the following reasons : 1 ) the inverse technique can shorten the length of time for urologic surgeons to put the tissue on the blades during the morcellation .
2 ) the inverse technique can prevent the tissue from interfering with the visual field in the posterior wall of the bladder during the morcellation .
3 ) the inverse technique can maintain the distance between the blades and the bladder wall to a sufficient extent , thus continuing the morcellation with no interruptions .
ishikawa et al . , who first introduced the inverse technique , performed holep surgery for 140 patients with bph during a period ranging from january to december 2010 . according to those authors , the mean morcellation time and
in addition , they also noted that there were no complications such as bladder injury during the morcellation .
furthermore , they also reported that there was a decreasing tendency in the morcellation efficiency in patients with a weight of enucleated tissue of > 80 g. furthermore , the morcellation efficiency was significantly poor in patients with a weight of enucleated tissue of > 100 g. in the current study , we compared the morcellation efficiency and the incidence of bladder injury during the morcellation according to prostate size .
this comparison showed that both values were higher in the group with a prostate size of 50 g than in the group with a prostate size of < 50 g. however , this was not statistically significant ( table 4 ) .
there are limitations of the current study as shown below : 1 ) the current study was conducted under a retrospective cross - sectional design .
2 ) a smaller number of patients underwent the upward technique as compared with the inverse technique .
moreover , the complications occurred at a lower incidence during the morcellation in both groups ( the upward technique group and the inverse technique group ) .
theoretically , morcellation is a simple procedure for holep . in practice , however , it is one of the complicated procedures of this surgical modality and requires special attention .
urologic surgeons should therefore be careful not to cause complications such as bladder mucosal injury or perforation . as described in the current study
, the inverse technique might be a more effective , safer , and more excellent method of morcellation as compared with the conventional upward technique .
 purposewe developed an inverse technique for tissue morcellation by modifying the conventional upward technique and then examined its safety and efficiency.materials and methodsfrom july 2008 to december 2010 , a total of 389 consecutive patients treated with holmium laser enucleation of the prostate ( holep ) were enrolled in this study . for tissue morcellation , we used an upward technique for an initial series of 84 patients and an inverse technique for a consecutive series of 305 patients . 
 we compared efficiency and safety between the inverse technique and the upward technique.resultsthere were no significant differences in mean age or prostate volume between the two groups . 
 the mean morcellation efficiency was higher in the inverse technique group . 
 the incidence of severe bladder injury was significantly higher in the upward technique group . 
 regarding the site of bladder injury , 7 and 4 cases of bladder injury occurred in the bladder dome and posterior wall , respectively , in the upward technique group . in the inverse technique group 
 , however , the site of bladder injury was limited to the trigone . 
 we divided our clinical series of patients into the upward technique group and three inverse technique groups on the basis of the timing . 
 the mean morcellation efficiency was significantly higher in all three inverse technique groups than in the upward technique group . 
 however , there was no significant difference in mean morcellation efficiency between the three inverse technique groups.conclusionsin conclusion , the inverse technique might be a more effective , safer , and more excellent method of morcellation than the conventional upward technique . 
INTRODUCTION
MATERIALS AND METHODS
1. Patients
2. Surgical technique
3. Equipment
4. Surgical treatment outcomes
5. Statistical analysis
RESULTS
DISCUSSION
CONCLUSIONS