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Infertility

revalence of Sperm in the Post-Ejaculatoryrine of Fertile and Subfertile Men

ark Sigman, Karen Boyle, and Jon P. Jarow

BJECTIVES The purpose of this study was to determine the prevalence of sperm within post-ejaculatory urinein both fertile and infertile men.

ETHODS Fifteen men of proven fertility and 66 non-azoospermic men being evaluated for infertility wererecruited in two academic centers. Laboratory studies included a semen analysis and theexamination of post-ejaculate urine for the presence and concentration of sperm.

ESULTS The median total urine sperm count for the fertile group (26.6 million) was not significantlygreater than the infertile group (8.3 million, P � 0.63). The median percentage of total sperm(urine plus semen) present in urine for the fertile group (14.8%) was not different from that inthe infertile group (15.3%, P � 0.36). Sperm were found in the urine of 73% of fertile and 65%of infertile patients (P � 0.54).

ONCLUSIONS The prevalence of sperm in the post-ejaculatory urine in the fertile population is similar to thatin infertile patients, which suggests that a great deal more information is needed to interpret this

test in the management of these patients. UROLOGY 71: 110 –112, 2008. © 2008 Elsevier Inc.

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ost-ejaculatory urinalysis (PEU) is used to detectejaculatory dysfunction during the evaluation ofinfertile men. The most common indications in-

lude aspermia (no antegrade seminal fluid during or-asm) or low volume ejaculate. Although recommenda-ions for the interpretation of a PEU have beenublished, evidenced-based standard criteria do not cur-ently exist.1,2 The purpose of this study was to assess aopulation of fertile and infertile men to determine therevalence of sperm within post-ejaculatory urine andain insight into the interpretation of this test.

ATERIAL AND METHODS

e prospectively recruited a group of 15 men of proven fertilityequesting elective vasectomy for the control group. We re-ruited a consecutive series of 80 men being evaluated fornfertility for the infertile group. Institutional review boardpproval was obtained for this study. All men underwent aistory and physical exam. Laboratory evaluation included aomplete semen analysis and post-ejaculatory urinalysis. Pa-ients were excluded from analysis if they were completelyzoospermic and had no sperm present within both the semennd the urine. Patients with sperm in both the semen and therine, in the semen only, or in the urine only were included inhe analysis. Semen was collected after a 2- to 3-day abstinenceeriod. Patients masturbated into a clean specimen cup. As

his work was supported by NICHD Grant R01 HD 44258-01From the Division of Urology, Department of Surgery, Brown University, Provi-

ence, Rhode Island; and Johns Hopkins University School of Medicine, Baltimore,arylandReprint requests: Dr. Mark Sigman, Suite 174, 2 Dudley Street, Providence, RI

e2806. E-mail: mark_sigman@brown.eduSubmitted: June 13, 2007; accepted (with revisions): September 22, 2007

10 © 2008 Elsevier Inc.All Rights Reserved

oon as the men were able, they urinated into a second speci-en container. The samples were analyzed within 2 hours of

ollection. Semen was analyzed for volume, sperm concentra-ion, and motility. Urine was centrifuged at 450 � g for 10inutes. The pellet was resuspended in 1 mL with sperm washedium and sperm concentration determined. Total sperm

ounts in the semen and urine were calculated.Untransformed total sperm counts were compared with theann-Whitney U-test for independent groups. Total sperm

ounts were also logarithmically transformed to normalize theistribution of the data and means compared with Student-test. We compared ratios (the percentage of patients withperm in the urine) using Chi-square analysis. Simple linearegression was used to examine the relation between individualariables. The relative value of total semen sperm count, pa-ient age, and semen volume as predictors of urine total spermount or percentage of total sperm count present in the urineas examined by multivariate stepwise linear regression. Statis-

ical analysis was performed using WINKS software (Lavasoft,exas).

ESULTSone of the 15 fertile patients had azoospermia, whereas

4 patients in the infertile group had azoospermia andere excluded. The remaining 66 infertile patients were

ncluded in the analysis. The mean age of the fertile men36.7 years) was not different from the infertile patients39.8 years, P � 0.17). As expected, the median totalemen sperm count of the fertile men (128 million) wasignificantly higher than the infertile patients (14 mil-ion, P �0.001) (Table 1). Although the median totalrine sperm count for the fertile group (26.6 million) wasreater than the infertile group (8.3 million) the differ-

nce was not significant (P � 0.63). The median per-

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entage of total sperm (sperm in semen plus sperm inrine) for the fertile group (14.8%) was no different fromhat in the infertile group (15.3%, P � 0.36). When aositive PEU was defined as any sperm in the urine, 73%f fertile patients had a positive PEU whereas 65% ofnfertile patients were positive (no difference, P � 0.54).n the fertile group 1 of 15 patients had more sperm inhe urine than in the semen. In the infertile group 25 of5 patients had this finding.There are two potential methods to define a positive

EU. One option is to arbitrarily select an absoluteumber of sperm in the urine, above which a patientould be classified as having a positive PEU and belowhich he is negative (Fig. 1). The alternative approach is

o calculate the percentage of the total sperm countresent within the urine and define a positive PEU basedn an arbitrarily selected percentage of sperm in therine. The total number of sperm is defined as the totalperm count in the semen (density times volume) plushe total number of sperm in the post-ejaculate urine.he percentage of sperm in the urine is calculated byividing the number of sperm in the urine by the totalumber of sperm times 100. The graph in Figure 2 wasenerated by plotting the prevalence of a positive PEU%) with ever-increasing threshold percentage values forur two populations. As the threshold for a positive PEU

Table 1. Group semen volume and total semen spermcounts

Group

SemenVolume

(mL) � SD

Median Total SemenSperm Count

(millions)

25% to 75%Quartiles(millions)

Fertile 2.1 (1.0) 14.3 3.7–56.8Infertile 1.8 (1.2) 128 102–156

Semen volumes are means and standard deviations (SD). Totalsemen sperm counts are medians with 25% to 75% quartileranges.

igure 1. Relationship between threshold of total numberperm present in the urine and percentage of patients whoxceed that threshold and would be considered to have aositive PEU. Differences between fertile and infertile pa-ients were not different at any threshold (P �0.05).

ncreased, the prevalence of a positive PEU decreased in s

ROLOGY 71 (1), 2008

oth the fertile and infertile groups, with the prevalenceending to be higher in the infertile group (Fig. 2). In theertile group the 95% confidence interval of the percent-ge of sperm in the urine is 0% to 67.6%. In contrast, the5% confidence interval for the infertile group is 0% to00%. The distribution of the percentage of total spermn the urine revealed a unimodal distribution in theertile group, whereas a bimodal distribution was presentn the infertile patients (Fig. 3).

Semen volume and the total urine sperm count (logransformed) were negatively correlated in the infertileroup (r � �0.3, P � 0.003) whereas, possibly because ofhe small sample size, there was no significant relation-hip in the fertile group (P � 0.29). Although patient ageas negatively related to total urine sperm count (log

ransformed), the correlation was not statistically signif-cant in either the fertile or infertile group (r � �0.1,

� 0.693 fertile; r � 0.2, P � 0.099 infertile). Inultivariate stepwise linear regression, the variables age,

igure 2. Relationship between threshold of percent totalperm present in the urine and percentage of patients whoxceed that threshold and would be considered to have aositive PEU. Differences between fertile and infertile pa-ients were different at the 50% and 75% thresholdsP �0.05).

igure 3. Frequency distribution of percentage of totalperm found in the urine in the fertile and infertile popula-ions reveal a different pattern, unimodal versus bimodal,espectively.

emen volume, and total semen sperm count (log trans-

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ormed) were examined as predictors of the urine totalperm count (log transformed). Age, semen volume, andemen total sperm count all added to a linear regressionodel but the contribution of age was not statistically

ignificant (P � 0.151). In this model, 41% of the vari-tion in total urine sperm count is accounted for by thesehree variables. In the fertile group, only the semen totalperm count added to the model, with 30% of variationn the urine total sperm count accounted for by theemen total sperm count.

Using stepwise multivariate linear regression, we ex-mined the ability of patient age, semen volume, andotal semen sperm count to predict the percentage ofotal sperm in the urine. In the infertile group, age andemen volume remained significant variables whereas to-al semen sperm count did not. The variables age andemen volume accounted for 31% of variation in per-entage of sperm in the urine. Semen volume was nega-ively correlated whereas age was positively correlatedith percentage of sperm in the urine. In the fertileroup, none of the variables were strong predictors of theercentage of sperm in the urine.

OMMENTjaculation involves a coordinated series of events in-luding the deposition of semen in the posterior urethra,pening of the external sphincter, and closure of theladder neck. The presence of sperm in the post-ejaculaterine is considered diagnostic of retrograde ejaculation;owever, there is no consensus as to what the preciseriteria are for a PEU to be considered positive. More-ver, the presence of sperm in the PEU may be due toither true retrograde ejaculation or residual sperm in therethra that are washed out with voiding. The force ofentrifugation required to pellet all sperm in urine hasot been studied. In semen, all sperm will not pellet event 3000 � g; however, urine is much less viscous.3 It isikely that the vas majority of sperm will pellet at forcesver 300 � g, which is the commonly used force forperm washing.

It is now clear that even fertile men have sperm in theEU. In our population, approximately two thirds ofen, both fertile and infertile, had sperm in the PEU.his is similar to observations in prior studies where only

nfertile patients were evaluated. Both Weissenberg4 andriagno5 found sperm in the PEU in over 90% of infer-

ile patients. We found that the median percentage ofperm present in the urine of fertile and infertile patientsas approximately 15%. Although the medians were the

ame in both groups, the frequency distributions of thewo groups were different. The infertile population had a

imodal distribution reflecting the presence of a large

12

umber of men with normal ejaculatory function andnother subgroup of men with ejaculatory dysfunction.his implies that, as expected, in normal fertile men most

emen and sperm are present in the antegrade ejaculatehereas a proportion of infertile men have true retro-rade ejaculation. When defining a positive PEU by anbsolute number of sperm present in the urine, there wereo differences between fertile and infertile populations.hus, defining a positive PEU by a threshold of theercentage of total sperm present in the urine may betterdentify men with ejaculatory dysfunction.

In the infertile group, the percentage of sperm in therine was negatively correlated with age and semen vol-me. This was not found in the fertile group, perhapsecause of the smaller sample size or that the etiology ofpositive PEU in fertile men is different from that of

nfertile men. Infertile patients with partial retrogradejaculation would be expected to have lower semen vol-me, thus accounting for the negative correlation in thisroup. Fertile patients would not be expected to haveetrograde ejaculation or low volume ejaculates and thusould not be expected to demonstrate a correlation be-

ween the percentage of sperm in the urine and semenolume. The fertile group ranged in age from 30 to 47ears old, a small range compared with the infertile grouprange 26 to 66 years old). This may have accounted forhe lack of a correlation of percentage of sperm in therine and age in the fertile group. Because the studyndicates that significant numbers of sperm may beresent in the PEU of infertile patients, patients with lowotal sperm count may be candidates for PEU analysishether or not the seminal volume is low.The prevalence of sperm in the PEU in the fertile

opulation is similar to that in infertile patients, whichuggests that a great deal more information is needed tonterpret this test in the management of these patients.

oreover, it is unclear from this study whether the spermound in the urine is coming from the bladder urine orimply being washed out of the urethra.

eferences. Sigman M, and Jarow JP: Male infertility, in Walsh PC, Retik AB,

Vaughan ED Jr , et al. (Eds): Campbell’s Urology, Saunders, 2002, pp1475–1531.

. World Health Organization: WHO Laboratory Manual for the Exam-ination of Human Semen and Sperm–Cervical Mucus Interaction, NewYork, Cambridge University Press, 1999.

. Corea M, Campagnone J, and Sigman M: The diagnosis of azoosper-mia depends on the force of centrifugation. Fertil Steril 83: 920–922, 2005.

. Weissenberg R, Rozenman H, Hova M, et al: The diagnostic value ofsperm in post-ejaculatory urine. Int J Androl 7: 142–148, 1984.

. Ariagno JI, Mendeluk GR, Pugliese MN, et al: The only presence ofsperm in urine does not imply retrograde ejaculation. Arch Androl

51: 431–436, 2005.

UROLOGY 71 (1), 2008