***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Objectives To assess the role of power and color Doppler ultrasonography ( US ) in patients with azoospermia prior to testicular sperm extraction . Methods One hundred and thirty consecutive patients with azoospermia were assessed in this prospect i ve study . Based on a semiquantitative method , the results of power Doppler US were grade d into three categories : grade 1 , no visible vessels ; grade 2 , between one and three detectable vessels ; grade 3 , more than three detectable vessels . The location of each visible vessel was also recorded as upper , middle or lower third of the testis . Results Seventy-four patients with non-obstructive azoospermia ( NOA ) and 27 with obstructive azoospermia ( OA ) fulfilled the study criteria . OA patients revealed a significantly higher intratesticular perfusion compared with NOA patients . NOA patients with higher intratesticular perfusion required fewer biopsies for successful sperm retrieval . Moreover , a correlation was noted between the presence of visible vessels in each segment and the probability of successful sperm retrieval during biopsy from the corresponding segment . Conclusions Our data indicate that a semiquantitative , simplified power Doppler US assessment is capable of localizing areas containing viable sperm with the potential to direct biopsies to specific sites and subsequent decrease in the number of required biopsies OBJECTIVE To prospect ively evaluate the role of intratesticular vascular flow in modulating sperm function in men with obstructive and nonobstructive azoospermia . The correlation of testicular Doppler values with  nitric oxide and testicular sperm extraction  was further evaluated . DESIGN Prospect i ve study . SETTING Assisted reproduction unit at a university center . PATIENT(S ) Twenty-eight men with azoospermia undergoing sperm extraction for intracytoplasmic sperm injection .  INTERVENTION(S ) Ultrasound and color Doppler scanning of the testes . Testicular sperm retrieval and nitrite/nitrate assay . MAIN OUTCOME MEASURE(S )  Doppler analysis of testicular transmediastinal artery , plasma and seminal plasma nitrite/nitrate values , and sperm extraction histopathology .  RESULT ( S ) The pulsatility index ( PI ) of the transmediastinal artery was higher in patients with nonobstructive azoospermia ( PI = 1.40 + /- 0.13 ) than in those with obstructive azoospermia ( PI = 1.09 + /- 0.15 ; P=.011 ) . Seminal plasma nitrite/nitrate concentrations were more elevated in cases of obstructive azoospermia than in gonadal failure . Unsuccessful sperm recovery was observed in four patients who showed the worst indices of gonadal failure . In this subgroup , a transmediastinal PI value > 1.50 was always observed . CONCLUSION ( S ) Doppler analysis of the transmediastinal artery and nitrite/nitrate seminal plasma concentrations are useful for distinguishing between obstructive and nonobstructive azoospermia and allow the identification of the presence of spermatozoa within the testes OBJECTIVE To see whether testicular sperm extraction could be used to perform intracytoplasmic sperm injection ( ICSI ) for men with nonobstructive azoospermia caused by maturation arrest . DESIGN Uncontrolled prospect i ve trial of an attempt to find occasional elongated spermatids or spermatozoa in testes of azoospermic patients with maturation arrest and to use these haploid cells for ICSI . SETTING European university-based center for reproductive medicine and private American community hospital . PATIENTS Thirty-eight azoospermic males without obstruction and with biopsy-documented maturation arrest , seven of whom elected , with their wives , to undergo scrotal exploration and testicular sperm extraction with ICSI  in an attempt to become pregnant . INTERVENTIONS Histologic evaluation of spermatid development in 38 patients with azoospermic maturation arrest . Testicular sperm extraction with ICSI in seven r and om volunteers from this group . MAIN OUTCOME MEASURES Presence or absence of mature spermatids in the testis biopsy specimen of patients with azoospermic maturation arrest . Fertilization , cleavage , and pregnancy after testicular sperm extraction and ICSI  in patients with azoospermic maturation arrest . RESULTS All seven patients with azoospermic maturation arrest had occasional sperm found with testicular sperm extraction . Five had sufficient numbers ( between 6 and 30 ) for ICSI , and those five had ETs . In four , the partners became pregnant . In all 38 patients examined , the maturation defect was in meiosis rather than in spermiogenesis . CONCLUSION Nonobstructive azoospermia caused by maturation arrest may be treated with testicular sperm extraction with ICSI apparently as successfully as Sertoli cell only Little is known about the efficacy and the factors affecting the outcome of fine needle aspiration biopsy of the testis for sperm retrieval in azoospermic men with defective spermatogenesis . A prospect i ve study was design ed to compare the efficacy of needle and open ( window ) testicular biopsies for testicular epididymal sperm extraction ( TESE ) in 35 consecutive men with azoospermia due to defective spermatogenesis undergoing testicular biopsy for intracytoplasmic injection of oocytes . Each of the consecutive 35 patients underwent TESE using a 19 gauge butterfly needle followed by a window ( 1 - 1.5 cm-sized incision ) testicular biopsy in the same procedure . The extraction of spermatozoa into culture medium was compared with the assessment of testicular biopsies by histology , the mode of biopsy ( needle or open biopsy ) and the amount of tissue retrieved by either method . Testicular spermatozoa were retrieved in 22 ( 63 % ) who had an open testicular biopsy compared with five ( 14 % ) patients who had multiple needle biopsies , respectively ; the difference was statistically significant . Open testicular biopsy  retrieves more testicular tissue than needle biopsy . Needle testicular biopsy  retrieved testicular spermatozoa in 50 % of those with hypospermatogenesis , 10 % with focal spermatogenesis and in no patients with maturation arrest or Sertoli cell-only pattern . In contrast , sperm retrieval was successful in 100 % , 90 % and 66 % of those with respective histologies using open testicular biopsy . Other than bruising , for which they required no analgesia , none of the patients suffered any obvious complications associated with traditional testicular biopsy . We conclude that open testicular biopsy is more effective than needle biopsy for the retrieval of testicular spermatozoa in azoospermic men with defective spermatogenesis . The difference observed may be related to the amount of testicular tissue retrieved and to the influence of testicular histology Azoospermia is defined as the absence of spermatozoa in the ejaculate , although some foci of spermatogenesis may exist in the testes of these men . Currently , there are no clinical , seminal or hormonal parameters for identifying spermatogenesis within the testis sufficient for achieving genetic offspring . As a result , multiple biopsies are performed at several arbitrary sites of both testes in search of spermatozoa . We developed a power Doppler ( PD ) ultrasound ( US ) image-based technique that predicts sites with the greatest potential for spermatogenesis . PDUS images of the testes of azoospermic men were acquired at seven cross-sections to reconstruct a 3-D matrix for constructing a spatial map of preferential regions where spermatozoa are most likely to exist . This technique may obviate the need for arbitrary multiple biopsies that inflict some degree of damage upon testicular tissue , and may increase the success rate of identifying viable spermatozoa in testicular biopsies OBJECTIVE To evaluate the outcomes of microdissection testicular sperm extraction ( micro-TESE ) in patients with high FSH . DESIGN Clinical retrospective study . SETTING Department of urology at a tertiary university hospital . PATIENT(S ) Seven hundred ninety-two men with nonobstructive azoospermia . INTERVENTION(S ) Micro-TESE followed by intracytoplasmic sperm injection was performed . The men were classified into four groups based on serum FSH levels : < 15 , 15 - 30 , 31 - 45 , and > 45 IU/mL. MAIN OUTCOME MEASURE(S ) Sperm retrieval , clinical pregnancy , and live birth rates . RESULT ( S ) Testicular sperm were successfully retrieved in 60 % of the men . Sperm retrieval rates in the groups of men with FSH values 15 - 30 , 31 - 45 , and > 45 IU/mL was 60 % , 67 % , and 60 % respectively ; this was higher than the group of men with FSH < 15 ( 51 % ) . Of those men who had sperm retrieved , clinical pregnancy and live birth rates were similar in the four groups ( 46 % , 50 % , 52 % , 46 % and 38 % , 45 % , 44 % , 36 % , respectively ) . CONCLUSION ( S ) The chances of sperm retrieval using micro-TESE is just as common , if not better for men with elevated FSH levels than for men with lower FSH . Micro-TESE results appear to differ from earlier series that report low retrieval rates with r and om biopsies for men with elevated FSH . High FSH is not a contraindication for micro-TESE In a population of non-obstructive azoospermia patients , the efficacy of microsurgical testicular sperm extraction ( microTESE ) and conventional TESE was evaluated in a r and omized controlled study on 138 testicles , classified and paired in a 48-square table according to the different classes of the following three variables :  patient plasma FSH concentration , orchidometry and testicular histology . Sperm retrieval was positive in 21/22 testicles with hypospermatogenesis ( 11/11 , 10/11 ; microTESE , TESE respectively ) , in 12/14 with maturation arrest ( 6/7 , 6/7 ) , in 16/22 with incomplete Sertoli cell-only syndrome ( 8/11 , 8/11 ) , and in 16/80 with complete Sertoli cell-only syndrome ( 11/40 , 5/40 ) . Sperm recovery was positive in 5/24 patients with FSH concentration > or = 3 x maximum value of normal range ( N ) ( 4/12 , 1/12 ) , in 17/40 patients with 2N < or = FSH < 3N ( 9/20 , 8/20 ) , in 30/48 patients with N < FSH < 2N ( 17/24 , 13/24 ) , and in 13/26 patients with FSH = N ( 6/13 , 7/13 ) . Regarding orchidometry , sperm recovery was positive in 11/18 testicles with volume ( V ) > or = 12 ml ( 6/9 , 5/9 ) , in 27/56 testicles with 8 ml < or = V < 12 ml ( 15/28 , 12/28 ) , and in 27/64 testicles with V < 8 ml ( 15/32 , 12/32 ) . FSH value and the surgical procedure were the two variables significantly ( P < 0.05 ) predicting positive sperm retrieval OBJECTIVE To perform conventional and microdissection testicular sperm extraction ( TESE ) at the same session and compare their effectiveness . DESIGN Prospect i ve comparative study . SETTING University hospital setting . PATIENT(S ) The study included 335 patients with nonobstructive azoospermia . INTERVENTION(S ) Microdissection TESE was performed to 77 patient with atrophic testes . An additional 258 patients underwent conventional TESE using three incisions on three quadrants of the testis ( upper , middle , and lower ) . Microdissection TESE was performed by enlarging the middle incision vertically when no spermatozoa could be detected using the conventional technique . MAIN OUTCOME MEASURE(S ) Sperm retrieval , fertilization , clinical pregnancy rate ( PR ) , and live birth rate were evaluated . The relation between sperm retrieval rate and FSH level and testis volume was also investigated . RESULT ( S ) Spermatozoa was detected in 33.7 % of patients using conventional TESE . The spermatozoa detected increased to 50.8 % using microdissection TESE . The increase was statistically significant . In the primary microdissection TESE group , the surgical retrieval rate was 20.8 % . The overall sperm retrieval rate was 43.9 % . There was a significant relation between the sperm retrieval rate and testis volume , whereas there was no relation between sperm retrieval rate and FSH levels . The overall fertilization rate , clinical PR , and live birth rate were 57.1 % , 50.4 % , 36.4 % , respectively . CONCLUSION ( S ) Conventional TESE combined with microdissection TESE can be used in selected patients . Sperm retrieval rate of TESE can be low in patients with atrophic testes Intracytoplasmic sperm injection ( ICSI ) with testicular spermatozoa and ejaculated spermatids has been applied successfully to treat infertility because of azoospermia due to obstruction or testicular failure . In most cases , free spermatozoa are recovered from testicular tissue after mechanical mincing of multiple biopsies . Testicular sperm retrieval , however , remains unsuccessful in a high proportion of male patients suffering from testicular failure . In the present study , four media for enzym 
    Output:
    
Meta-regression analysis demonstrated that SRR per cycle was independent of age and hormonal parameters at enrolment .
However , the SRR increased as a function of testis volume .
WIDER IMPLICATION S This analysis shows that cTESE/mTESE in subjects with NOA results in SRRs of up to 50 % , with no differences when cTESE was compared to mTESE .
Retrieved sperms result ed in a LBR of up to 28 % ICSI cycle .