Shorter Obstructive Intervals and Motile Sperm on Intraoperative Vasal Fluid Evaluation Predict Favorable Semen Parameters Following Vasovasostomy

ABSTRACT

Background

Vasectomy reversal is the primary method of fertility restoration for men who wish to pursue natural conception following vasectomy. The existing body of literature evaluating vasovasostomy (VV) success is primarily focused on endpoints that capture the presence or absence, rather than the quantity and quality, of sperm in postoperative semen analyses (SAs).

Objectives

To identify reproductive and surgical factors associated with favorable postoperative semen parameters in men who underwent bilateral VV.

Materials and Methods

We performed a retrospective study of men meeting strict inclusion criteria who underwent bilateral VV at a large academic center. Postoperative semen parameters, operative findings, and clinical characteristics were analyzed. Associations between predictors and semen outcomes were evaluated using univariate linear and logistic regression models.

Results

One hundred men who underwent bilateral VV were included in the final analysis. The median age was 39.9 years, and the median obstructive interval was 8.6 years. Those with motile sperm on initial postoperative SA had shorter mean obstructive intervals (8.1 vs. 11.0 years, p = 0.04) and had a higher proportion of motile sperm in vasal fluid during intraoperative assessment (51.1 vs. 8.1%, p = 0.01). Fifty‐eight percent of men (n = 44/76) exhibited a TMSC > 4.55 million, the lowest TMSC with a confirmed spontaneous pregnancy in our cohort. Motile sperm on postoperative SA were best predicted by the intraoperative presence of motile sperm in vasal fluid (OR: 11.51, 95% CI: 1.43–93.01, p = 0.02) and shorter obstructive intervals (OR: 0.87, 95% CI: 0.76–0.99, p = 0.04) on univariate regression. Postoperative normozoospermia was associated with shorter obstructive intervals (OR: 0.80, 95% CI: 0.69–0.92, p = 0.002) but was not statistically associated with the intraoperative presence of motile sperm.

Discussion

These findings highlight the utility of intraoperative vasal fluid evaluations for postoperative prognostication.

Conclusion

Intraoperative sperm motility and obstructive interval duration are predictive of postoperative semen quality.

1. Introduction

Vasectomy reversal (VR) is a well‐established surgical option to restore fertility in men following elective sterilization [1, 2, 3, 4]. To determine the appropriate surgical technique, surgeons routinely assess fluid quantity and characteristics from the testicular margin of the incised vas deferens for the presence of motile or nonmotile sperm and/or sperm parts [5, 6]. Vasovasostomy (VV), which involves microsurgical anastomosis of the vas deferens, is the most commonly performed type of VR and is indicated when intact sperm, sperm parts, or copious clear vasal fluid are identified [7].

Many studies assessing VR outcomes have relied on either patency or pregnancy as their primary endpoints [6, 8, 9, 10, 11, 12, 13]. Patency, typically defined by the presence of any quantity of sperm in the postoperative ejaculate, provides a binary measure of success but does not capture the broader spectrum of semen quality that influences the likelihood of natural conception [10, 12, 14, 15, 16]. Likewise, pregnancy and live birth are crucial clinical outcomes, but they are strongly affected by female partner factors and therefore do not exclusively reflect surgical success [14, 17, 18]. In contrast, a postoperative semen analysis (SA) captures the broader spectrum of semen quality independent of female factors.

Quantitative SA parameters such as sperm concentration, percent motility, and total motile sperm count (TMSC) offer critical insights into male fertility potential and correlate with time to pregnancy [19, 20, 21]. Few VR studies, however, have evaluated how often men achieve clinically meaningful thresholds (such as postoperative normozoospermia) or what perioperative factors drive or predict these outcomes [20, 22]. Consequently, clinicians would benefit from evidence‐based guidance on how intraoperative and perioperative observations predict postoperative semen parameters [6, 7, 23]. Such insight would influence counseling and management decisions, such as intraoperative sperm cryopreservation.

An intraoperative vasal fluid assessment is typically used to confirm epididymal and vasal patency, but others have suggested that it may hold predictive value for postoperative semen quality [6, 8, 19]. Moreover, the obstructive interval has emerged as a consistent and unbiased predictor of postoperative success [14, 24, 25, 26]. Although well‐established in relation to patency and pregnancy, its effect on quantitative semen parameters also remains less clearly defined [19, 20].

We aimed to advance our understanding of how postoperative semen parameters relate to obstructive interval duration and the presence of motile sperm in intraoperatively assessed vasal fluid. To address these limitations, we analyzed a cohort of men who underwent bilateral VV, examining patient and perioperative factors associated with quantitative postoperative semen parameters. Our findings relate patient characteristics and perioperative factors to postoperative semen quality, providing physicians with evidence to enrich their patient‒doctor interactions, especially in the context of postoperative counseling.

2. Materials and Methods

2.1. Cohort Selection

We conducted a retrospective cohort study of 159 men who underwent VR between April 2014 and September 2024 at a large academic center. All procedures utilized an operating microscope and were performed by one of five urologists with fellowship training in reproductive urology and microsurgery. Our analysis excluded those who required vasoepididymostomy (VE; n = 25) or were not reconstructed on one or both sides (n = 2). All remaining cases were bilateral VV, which were performed using either a two‐layer or modified single‐layer anastomosis technique. Other exclusions included patients who underwent vasal reconstruction for postvasectomy pain syndrome (PVPS) (n = 5), patients with a prior history of failed VR (n = 2), those without available postoperative SA, or those without documented fertility outcomes (n = 25). The resulting cohort included 100 cases for analysis.

2.2. Variables

Selected demographic, medical, reproductive, and operative variables were manually abstracted from the electronic medical record (EMR) in a standardized fashion. Preoperative variables included age and BMI at the time of VV and any history of alcohol use, smoking, hypertension, or hyperlipidemia before VV. Intraoperative variables were collected from the surgical note and included vasal fluid characteristics, operative time, obstructive interval, and cryopreservation. Vasal fluid characteristics were evaluated intraoperatively and categorized by the operating surgeon as containing motile sperm, nonmotile sperm with or without sperm parts, or no sperm. Postoperative variables included prednisone use, pregnancy, and time between surgery and SA. Prednisone use was limited to cases where it was prescribed by the surgeon of record for postoperative management. Pregnancy was categorized as generalized pregnancy (one with an unknown mode of conception) or spontaneous pregnancy. Postoperative semen variables included the abstained period, semen volume, sperm concentration, percent motility, normal morphology, TMSC, World Health Organization (WHO) sperm concentration classification category, and presence of sperm. The abstinence period and complete specimen collection was reported by the patient at the time of analysis. Patients were instructed to abstain from ejaculation for at least 2 days before their appointment. Semen volume (mL) was assessed using a serological pipette.

Sperm presence, sperm concentration, and percent motility were assessed using a Makler chamber and its associated protocol at room temperature. These variables were then used to calculate TMSC and assign WHO sperm concentration categories. Normal morphology was assessed by the Kruger Strict Morphology criteria and was evaluated using the Diff‐Quick staining method. These semen variables were obtained from formal SAs, which were performed in an accredited high complexity andrology laboratory using WHO fifth edition standards.

Finally, the presence of sperm was categorized as sperm present, motile sperm present, or no sperm present and determined from formal SA or, in some cases, via informal SA, where semen was assessed via office‐based microscopy by a reproductive urologist. This difference was due to provider preferences. The resulting dual collection method for the presence of sperm variables to measure patency may introduce a potential measurement error.

2.3. Study Endpoints

Study endpoints included the presence of motile sperm in the ejaculate, normozoospermia according to the WHO fifth edition standards, sperm concentration, and TMSC.

2.4. Statistical Analysis

Baseline characteristics were compared using chi‐squared tests for categorical variables and t‐tests for continuous variables. Univariate logistic regression was used to assess associations between predictor variables and binary semen outcomes. Univariate linear regression was used for continuous semen outcomes. Multivariable models were constructed for outcomes with significant univariate associations, with particular attention to the effect of the obstructive interval and vasal fluid quality. The predictive performance of logistic regression models was assessed using the area under the receiver operating characteristic curve (AUC). All statistical analyses were conducted using RStudio, with significance defined as a p < 0.05.

3. Results

3.1. Patient, Operative, and Semen Characteristics

A total of 100 men who met our strict inclusion criteria and underwent bilateral VV were included in the study cohort (Table S1). The median age at the time of VR was 39.9 years, and the median obstructive interval was 8.6 years. Hypertension and hyperlipidemia diagnoses were the most common comorbidities and were present in 16% (n = 16/100) and 13% (n = 13/100) of patients, respectively. Intraoperative sperm cryopreservation was performed at the time of VV in 32% (n = 32/100) of patients. Sperm or sperm parts were identified in 96% (n = 96/100) of all cases. Motile sperm were identified in vasal fluid intraoperatively in 46% (n = 46/100) of cases. Motile sperm were observed exclusively on the left in 14% (n = 14/100) of cases. Among these, the contralateral right vasal fluid contents contained nonmotile or sperm parts in 13 cases (n = 13/14) and no sperm in one case (n = 1/14). Motile sperm were observed exclusively on the right in 12% (n = 12/100) of cases. Among these, the left vasal fluid contents contained nonmotile or sperm parts in nine cases (n = 9/12) and no sperm in three cases (n = 3/12). Motile sperm were observed bilaterally in 20% (n = 20/100) of cases. Bilateral absence of sperm was identified in 3% (n = 3/100) of cases. Postoperative prednisone use, which was used at the discretion of the provider according to variable protocols, was documented in 17% (n = 17/100) of patients. Within the follow‐up period, pregnancy outcomes were available for 31% of individuals (n = 31/100), while the pregnancy outcomes of the remaining 69% of individuals were unavailable or negative (n = 69/100).

Seventy‐six men underwent formal laboratory SA, while 24 had informal office‐based SA documenting only the presence or absence of sperm. The postoperative SA was obtained at a median of 1.8 months after surgery. On initial postoperative SA, sperm were identified in 93% (n = 93/100) of men, with motile sperm being present in 88% (n = 88/100) of men. Among those with formal SAs, the median sperm concentration was 20.3 M/mL, and the median percent motility was 28.0%.

3.2. Presence of Motile Sperm

Men with motile sperm noted postoperatively were younger at the time of VV (39.7 vs. 45.0 years, p = 0.01) and had significantly shorter obstructive intervals (8.2 vs. 11.3 years, p = 0.01) compared to men without motile sperm. Intraoperative identification of motile sperm in vasal fluid was also far more common in this group (51.1 vs. 8.3%, p = 0.01; Table 1).

TABLE 1.

Patient, operative, and semen characteristics stratified by the presence of motile sperm on initial postoperative semen analysis.

Patient factors	Motile sperm on initial postoperative SA (n = 88)	No motile sperm on initial postoperative SA (n = 12)	p a
Preoperative
Median age at time of VV (years)	39.9 ± 7.2	45.0 ± 5.4	0.01
Median BMI (kg/m2)	28.8 ± 5.6	30.0 ± 7.9	0.25
Daily alcohol use (%)	14.8 (13)	0 (0)	0.33
Smoking history (%)	52.3 (46)	58.3 (7)	0.93
Hypertension (%)	12.5 (11)	41.7 (5)	0.03
Hyperlipidemia (%)	10.2 (9)	33.3 (4)	0.08
Intraoperative
Median operation time (min)	137.5 ± 40.3	129.0 ± 75.5	0.57
Median obstructive interval (years)	8.2 ± 5.5	11.3 ± 7.6	0.01
Cryopreservation during VV (%)	35.2 (31)	8.3 (1)	0.12
Motile sperm in vasal fluid (%)	51.1 (45)	8.3 (1)	0.01
Nonmotile sperm or sperm parts in vasal fluid (%)	44.3 (39)	91.7 (11)	0.69
Postoperative
Median time between surgery and semen analysis (months)	1.8 ± 1.4	1.7 ± 0.8	0.82
Postop prednisone use (%)	17.0 (15)	16.7 (2)	1.00
Median postoperative semen characteristics
Sperm concentration (M/mL) b	23.6 ± 37.7	0 ± 0.6	< 0.001
Percent motile (%) b	25.5 ± 33.3	N/A
Semen volume (mL) b	2.3 ± 2.0	2.2 ± 2.4	0.26
Normal morphology (%) b	3.0 ± 4.0	N/A
Abstinence (days)	3.0 ± 3.8	3.0 ± 1.5	0.48

Note: Bolded values represent statistically significant results (i.e., p < 0.05).

Abbreviations: BMI, body mass index, VV, vasovasostomy.

^a p values derived from univariate comparisons using t‐tests for continuous variables and chi‐squared tests for categorical variables.

^b Calculations derived from analysis of patients who underwent formal semen analysis (n = 76).

In univariate logistic regression, both the presence of motile sperm on either side in vasal fluid (OR: 11.5, 95% CI: 1.43–93.01, p = 0.02) and a shorter obstructive interval (OR: 0.87 per year, 95% CI: 0.76–0.99, p = 0.04) were significant predictors of motile sperm in the ejaculate. In contrast, the absence of motile sperm (e.g., the presence of nonmotile sperm or sperm parts on either side in vasal fluid) was associated with substantially lower odds of motile sperm presence in the ejaculate (OR: 0.07, 95% CI: 0.01–0.59, p = 0.01). Higher BMI (OR: 0.89, 95% CI: 0.81–0.99, p = 0.03), hypertension (OR: 0.20, 95% CI: 0.05–0.74, p = 0.02), and hyperlipidemia (OR: 0.23, 95% CI: 0.06–0.91) were also associated with lower odds of exhibiting motile sperm presence in the ejaculate (Table 2).

TABLE 2.

Predictors of motile sperm on postoperative semen analysis following bilateral vasovasostomy on univariate logistic regression.

Patient factors	Univariate odds ratio a	p b
Preoperative
Age at time of vas reversal (years)	0.89 (0.78, 1.00)	0.054
BMI (kg/m2)	0.89 (0.81, 0.99)	0.03
Smoking history	0.78 (0.23, 2.65)	0.69
Hypertension	0.20 (0.05, 0.74)	0.02
Hyperlipidemia	0.23 (0.06, 0.91)	0.04
Intraoperative
Operation time (min)	1.01 (0.99, 1.03)	0.43
Obstructive interval (years)	0.87 (0.76, 0.99)	0.04
Cryopreservation during VV	5.98 (0.74, 48.53)	0.09
Motile sperm in vasal fluid	11.51 (1.43, 93.01)	0.02
Nonmotile sperm or sperm parts vasal fluid	0.07 (0.01, 0.59)	0.01
Postoperative
Time between surgery and semen analysis (months)	1.23 (0.17, 8.98)	0.84
Postop prednisone use	1.03 (0.20, 5.17)	0.97
Postoperative semen characteristics
Sperm concentration on initial postoperative SA (M/mL)	1.83 (0.83, 4.07)	0.14
Semen volume on initial postoperative SA (mL)	1.35 (0.88, 2.06)	0.17
Abstinence period for initial postoperative SA (days)	1.36 (0.95, 1.95)	0.09

Note: Bolded values represent statistically significant results (i.e., p < 0.05).

Abbreviations: AUC, area under the curve; BMI, body mass index; SA, semen analysis.

^a Odds ratios for continuous variables are reported per unit increase.

^b p values derived from the univariate logistic regression model assessing the association between each predictor and the specified outcome.

The timing between surgery and the first postoperative SA varied (1.8 ± 1.4 months). To assess variability, we performed a secondary analysis comparing men who underwent SA before 2 months (n = 68/100) with those who underwent analysis at or after 2 months following VV (n = 32/100). No statistically significant differences in semen parameters were observed between these groups. Similarly, comparisons between patients with versus without documented abstinence duration demonstrated no significant differences in semen parameters.

3.3. Motile Sperm Recovery

Among those with only nonmotile sperm identified on the first postoperative SA (n = 5/100, 5%), follow‐up SAs revealed motile sperm in one man (n = 1/5, 20%), persistent nonmotile sperm in two men (n = 2/5, 40%), and azoospermia in two men (n = 2/5, 40%). No sperm were identified on the first postoperative SA in seven men (n = 7/100, 7%). Subsequent SAs revealed motile sperm in two men (n = 2/7, 29%), persistent azoospermia in three men (n = 3/7, 43%), and lack of follow‐up for the two remaining men (n = 2/7, 29%).

3.4. Sperm Concentration and Predictors of Normozoospermia

Among men with formal SA, univariate analysis showed that normozoospermia was associated with younger age at time of reversal (OR: 0.89, 95% CI: 0.81–0.99, p = 0.03) and shorter obstructive interval (OR: 0.80, 95% CI: 0.69–0.92, p = 0.002). Achieving normozoospermia had a weak negative correlation with hypertension (OR: 0.26, 95% CI: 0.07–0.97, p = 0.04) and a strong association with postoperative prednisone use (OR: 0.17, 95% CI: 0.05–0.58, p = 0.005; Table 3), although this result is confounded by the fact that prednisone use was used as a rescue treatment in a subset of our cohort.

TABLE 3.

Predictors of normozoospermia following bilateral vasovasostomy on univariate logistic regression.

Patient factors	Univariate odds ratio a	p b
Preoperative
Age at time of VV (years)	0.89 (0.81, 0.99)	0.03
BMI (kg/m2)	0.99 (0.91, 1.08)	0.87
Daily alcohol use	8.06 (0.97, 66.6)	0.053
Smoking history	0.83 (0.33, 2.10)	0.70
Hypertension	0.26 (0.07, 0.97)	0.04
Hyperlipidemia	0.79 (0.20, 3.23)	0.76
Intraoperative
Operation time (min)	1.00 (0.99, 1.02)	0.58
Obstructive interval (years)	0.80 (0.69, 0.92)	0.002
Cryopreservation during VV	1.08 (0.39, 3.04)	0.88
Motile sperm in vasal fluid	1.88 (0.74, 4.83)	0.19
Nonmotile sperm or sperm parts in vasal fluid	1.17 (0.07, 20.02)	0.92
Postoperative
Time between surgery and semen analysis (months)	1.55 (0.34, 6.96)	0.57
Postop prednisone use	0.17 (0.05, 0.58)	0.005
Postoperative semen characteristics
Semen volume on postoperative semen analysis (mL)	0.92 (0.68, 1.26)	0.62
Abstinence period on postoperative semen analysis (days)	1.05 (0.92, 1.20)	0.44

Note: Bolded values represent statistically significant results (i.e., p < 0.05).

Abbreviations: BMI: Body Mass Index, VV: Vasovasostomy.

^a Odds ratios for continuous variables are reported per unit increase.

^b p values derived from univariate logistic regression models assessing the association between each predictor and the specified outcome.

3.5. Pregnancy‐Associated TMSC Threshold

Of the 31 individuals (n = 31/100, 31%) with confirmed pregnancies following VV, 23 underwent formal SA (n = 23/31, 74%). Four of the couples conceived using assisted reproductive technology with ICSI/IVF (n = 4/31, 13%), while nine had a confirmed spontaneous pregnancy (n = 9/31, 29%). The remaining had an unknown method of conception (n = 18/31, 58%). The lowest recorded postoperative TMSC associated with spontaneous pregnancy was 4.55 million motile sperm. Overall, 44 of the 76 (58%) men who underwent formal SA following VV achieved a TMSC ≥ 4.55 million on initial postoperative SA. The relationship between the obstructive interval and postoperative TMSC is illustrated by a significant logarithmic decay pattern (p < 0.0007; Figure 1) on scatterplot analysis.

FIGURE 1.

Relationship between obstructive interval and postoperative total motile sperm count. Scatterplot depicting the negative logarithmic association between obstructive interval (years) and total motile sperm count (M) on initial postoperative semen analysis following vasectomy reversal. Each blue circle represents a patient with motile sperm identified in vasal fluid. Each orange triangle represents a patient with no motile sperm identified in vasal fluid. A log‐transformed regression line is overlaid with a 95% confidence interval, demonstrating decreasing sperm concentration with longer obstructive intervals.

4. Discussion

VV is the most common surgical approach for restoring fertility after vasectomy. While the binary presence or absence of sperm is a useful and unambiguous metric to report technical success, this parameter does not exclusively reflect the true biological outcome of interest (e.g., the ability to naturally conceive [6, 7, 8, 12]. Supplementing this variable with quantitative semen parameters (including sperm concentration, motility, and morphology) may offer a more objective assessment of fertility potential, yet this granularity in outcomes for a bilateral VV cohort remains underreported. The present study aimed to bridge this gap by evaluating how patient characteristics and perioperative factors are associated with postoperative semen parameters in a cohort of men undergoing bilateral VV. By analyzing both the binary presence of sperm and quantitative semen variables to find associated outcomes, we aimed to refine prognostic counseling and provide information about indications to pivot to alternative fertility strategies.

Shorter obstructive intervals and motile sperm during intraoperative vasal fluid assessment are both known indicators of VR success. Men with motile sperm in vasal fluid exhibited 12‐fold greater odds of having motile sperm in their first postoperative SA. In our analysis, 46% of men had motile sperm on at least one side found in their vasal fluid, among which 98% exhibited motile sperm in their first postoperative SA. In contrast, 50% of men had sperm or sperm parts in vasal fluid without motility, and only 78% of these men exhibited motile sperm on the first postoperative SA.

While prior research has emphasized vasal fluid assessment for intraoperative decision making between VV and VE, our findings analyze its additional value in anticipating postoperative semen quality in men undergoing bilateral VV [6, 16, 19, 27]. Our findings align with prior studies reporting that intraoperative presence of sperm in vasal fluid was predictive of patency and extend this literature by demonstrating that it was not predictive of normozoospermia [6]. Separately, we found that a postoperative SA revealing nonmotile sperm or azoospermia early on was a poor prognostic sign for sperm recovery. These two findings seem to argue that vasal sperm characteristics can predict sperm recovery. However, its failure to reach a significant difference for predicting normozoospermia demonstrates that its utility should be restrained to observe the risk of a postoperative signal. Therefore, the intraoperative presence of nonmotile sperm can be used to counsel the importance of a follow‐up SA, while an SA revealing nonmotile sperm or azoospermia early on should indicate additional SAs at regular intervals and consideration of cryopreservation during or soon after VR. Because of limited data, we cannot comment on whether these conclusions are applicable to cases where no sperm were identified during VR. Furthermore, the conclusions cannot inform whether a VE should have been considered, as patients may have had a similar result with either reconstructive technique.

As previously shown, the obstructive interval clearly plays a key role in this process. Each additional year of obstruction reduced the odds of achieving normozoospermia by 20%. While the subject odds ratio appropriately linked a longer obstructive interval to a lesser fertility outcome, its nature does not reflect absolute probability or the modest effects of a shorter obstructive interval. Importantly, the trends were only consistent across both binary and continuous semen parameters for the obstructive interval, reinforcing it as a predictor of semen quality, demonstrating the benefit of evaluating both binary and quantitative parameters, and indicating further analysis for vasal fluid assessment.

The use of prednisone to inhibit postoperative occlusion remains a relevant topic of VR research. In this study, prednisone was primarily used as a rescue treatment, as indicated by SA. A recent randomized controlled trial (RCT) evaluated the efficacy of prednisone at 1 year after surgery and found that routine high‐dose steroids worsened outcomes, but this study was not explicitly designed to assess the effectiveness of rescue prednisone compared to observation alone [28]. To a similar effect, our data revealed that 94% of men with a postoperative prednisone regimen had sperm return to their ejaculate, with no significant difference between median sperm concentrations compared to those without prednisone treatment. Since recovery of semen parameters is related to time, the difference in the rate of patency may be explained by a relatively earlier measurement in our study. When compared to the 4.55 million TMSC threshold for achieving pregnancy within our cohort, 80% of those treated with prednisone met this cutoff. The favorable difference of our prednisone treatment group reinforces the benefits of prednisone to inhibit anastomotic closure.

Pregnancy data in this cohort were limited, likely due to the large portion of patients who travel to our tertiary care facility for male fertility care and pursue postoperative and obstetric care closer to their home. All patients had a minimum of 1 year of follow‐up for pregnancy. However, the maximum duration of pregnancy follow‐up varied. Men who underwent VR in 2014 had an 11‐year follow‐up, whereas those who underwent surgery in 2024 had a 1‐year follow‐up. Accordingly, we were only able to observe descriptive coefficients. Notably, the lowest TMSC that resulted in a confirmed spontaneous pregnancy (where available) was 4.55 million. Fifty‐eight percent of men met or exceeded this threshold, which, barring female factors and providing adequate time, reflects a theoretical spontaneous pregnancy rate for this cohort.

We further sought to associate postoperative semen variables with external thresholds for conception. A 2021 population‐based study of over 5000 subfertile couples attempting natural conception identified a TMSC of 50 million best differentiated men who were more likely to naturally conceive within 5 years [29]. When applied to our cohort, 22% of men exceeded this TMSC. Furthermore, a 2011 study of 445 women undergoing 820 IUI cycles found that a TMSC of less than 1 million was not justified for IUI [30]. In our cohort, 16% of men had a TMSC of less than 1 million. It should be noted that there were two pregnancies with unknown modes of conception among this group. While these studies are not directly comparable to our own, they reinforce the idea that the TMSC following VR offers valuable insight into fertility counseling for varied clinical settings. Our data confirm that pregnancy remains stochastic to a degree and that the quality of sperm may play a more critical role, as indicated by the significantly lower TMSC in our cohort.

Several limitations of this study warrant consideration. The retrospective design introduces potential selection and reporting bias. Although strict exclusion criteria facilitated more meaningful results, the resulting modest sample size limited the ability to perform multivariable analyses for all outcomes. This included patients with subsequent SAs. In addition, the median time between the VV and the first postoperative SA was relatively early. While early postoperative SAs provide useful information regarding patency and initial semen quality, semen parameters may continue to improve over time following reversal, and early results may not fully reflect long‐term reproductive potential. Furthermore, variability in the timing of postoperative SAs and incomplete documentation of abstinence duration may introduce heterogeneity in measured semen parameters. However, sensitivity analyses did not demonstrate meaningful differences in semen parameters based on the timing of the first postoperative SA or the availability of abstinence data. Nevertheless, standardized postoperative testing intervals and defined abstinence durations would allow for more consistent assessment of semen quality in future studies. Variability in surgical technique and postoperative medication management introduced heterogeneity. Furthermore, only 76% of men in our cohort had formal SA results available in our EMR. In certain cases, formal testing was more likely to be obtained for visually suboptimal ejaculates, potentially biasing formal SA results toward poorer outcomes. In addition, a dual collection method to measure the presence of sperm introduced a potential measurement error. Furthermore, the focus on a bilateral VV cohort restricted us from being able to comment on the intraoperative decision between VV and VE. Finally, data regarding medication use, abstinence duration, and female partner fertility were incomplete or unavailable, limiting a comprehensive assessment of reproductive outcomes. Despite these limitations, this remains one of the few studies to link intraoperative vasal fluid assessment with semen outcomes in a clearly defined bilateral VV cohort. Future research should prioritize prospective data collection, continued evaluation of the interaction between vasal fluid characteristics and perioperative factors for intraoperative decision making, standardized postoperative SAs, and pregnancy tracking to validate the clinical utility of these intraoperative findings.

5. Conclusions

Intraoperative sperm motility and obstructive interval duration are predictive of postoperative semen quality.

Author Contributions

A.B., B.D.N., J.S., and S.D.L. conceptualized and designed the work, acquired the data and interpreted the results. All authors drafted or revised the manuscript.

Funding

The authors have nothing to report.

Disclosure

Scott D. Lundy had the following roles at the time of submission: Associate Editor of the Journal of Andrology; Consultant for Give Legacy; Board of Directors member for CADE Foundation; and Advisory Board Member for PS Fertility.

Supporting information

Supplemental Table 1: Patient, Operative, and Semen Characteristics of Men Undergoing Bilateral Vasovasostomy. Abbreviations: BMI: Body Mass Index, SA: Semen Analysis, VV: Vasovasostomy. ^**Formal Semen Analysis (n = 76).