Vasectomy is a form of permanent contraception which is increasingly considered as men age beyond mid-life. The procedure involves sealing a part of the vas deferens, preventing the transport of spermatozoa out of the testis. Vasectomy is achieved in two parts: exposing the vas deferens out of the scrotum (isolation) and blocking the vas (occlusion). Isolation can be done conventionally using a scalpel to make an incision through the scrotum or by a non-scalpel vasectomy (NSV). This involves clamping the vas and overlying skin by an extracutaneous ring and piercing the skin using pointed dissection forceps to gain access. The NSV technique is less invasive, with reduced damage to microvasculature, lymphatics and nerves, unlike the scalpel technique where these microscopic structures are more likely to be severed. Therefore, NSV may result in less trauma and post-procedure pain. As for occlusion, different methods were developed in order to reduce complications. These include excision and ligation, surgical clips, thermal or electrocautery, intraluminal mucosal cautery or chemical occlusion. However, excision and ligation are still the most widely used methods ^[1].

Complications of vasectomy can be classified as early or late. Early complications include acute pain, haematoma, bleeding, infection and trauma. Late complications are vasectomy failure, fistula formation and chronic pain ^[2]. Sperm granuloma or congestive epididymitis can present as either early or late complications. Post-vasectomy pain syndrome (PVPS), also known as chronic post-vasectomy pain, is formally defined as an intermittent or constant unilateral or bilateral testicular pain three months or longer in duration which significantly interferes with daily activities of the patient so as to prompt him to seek medical attention ^[3]. PVPS is a broad term that encompasses different presentations, such as: constant persistent scrotal pain, pain on ejaculation, pain during physical activity, dyspareunia and sensation of fullness of the vas deferens. Assessing chronic pain following vasectomy involves documenting the time of onset, duration, quality of pain, as well as using a visual analogue scale (VAS) to report severity.

Chronic pain following vasectomy is very challenging to diagnose and treat. Being a diagnosis of exclusion, it exposes the patient to a series of investigations and treatment regimens over months. Once a diagnosis is made, the treatment starts with non-invasive behavioural or pharmacological options. If these fail, patients might require invasive surgical interventions, such as repeating the vasectomy with wide excision of the severed ends, microdenervation of the spermatic cord, epididymectomy, vasectomy reversal or orchiectomy ^[4]. The last resort for patients with debilitating chronic pain is orchiectomy, despite one study by Sweeney et al. ^[5] stating that 80% of patients who underwent orchiectomy continued to experience pain.

Although chronic post-vasectomy pain is a recognized complication, current literature shows lack of consensus regarding its frequency. Recent narrative reviews report the incidence of post-vasectomy pain to be between 1% and 6% ^[6][7]. However, these reports were not derived from systematic reviews of the literature, and could therefore be biased. A Cochrane review by Cook et al. ^[8] details pain outcomes following scalpel versus non-scalpel vasectomy. It is noteworthy that post-vasectomy pain was not the main focus, only two randomized controlled trials were included for analysis, and observational studies were excluded from their review. Further, the two studies differed with respect to pain results, with one of them having a small sample size and high loss to follow-up. Therefore, there is still a significant gap in the literature so the objective of this study is to provide a more accurate picture of the incidence of post-vasectomy pain in contemporary clinical practice, rather than the more restrictive and less generalisable data extracted exclusively from randomized trials. This is the first systematic review and meta-analysis to investigate the incidence of post-vasectomy pain following traditional scalpel, compared to non-scalpel vasectomy.

2. Discussion

Literature reports have estimated the incidence of post-vasectomy pain to range between 1% to 6% ^{[6][7][8][9][10][11]}. In contrast, the results from the present systematic review and meta-analysis of all the available literature, show much higher frequencies with the overall average being 15%, following scalpel vasectomy at 24% and after NSV at 7%. However, in studies that reported on both scalpel and non-scalpel techniques, the difference was more modest, with 16.9% pain for scalpel vasectomy compared to 12.3% for NSV. With respect to the other/combined group where studies did not strictly fit into the scalpel or NSV groups, one may have expected that pain levels reported would fall between the scalpel and NSV groups, but it was actually higher than either non-scalpel or scalpel techniques at 35%. This result was due to high pain scores in two of the studies, one of which investigated a failed experimental vas occlusion technique ^[12] and the other which was an ultrasound study to detect mobile echogenicities ^[13]. The latter study had a control non-vasectomy group showing no statistical difference in pain compared to the vasectomy group. Across studies, the incidences of pain following conventional incisional scalpel vasectomy and NSV ranged between 5% to 79% and 0.6% to 26%, respectively. When scalpel, NSV and other/combined studies were included, the overall range of post-vasectomy pain was 0.6% to 79%. These were wide ranges, which resulted in significant heterogeneity, and may have been attributable to the different measures and follow-up durations of the studies. However, there may have been other unmeasured factors that also contributed to these differences. It is noteworthy that the majority of the studies in the NSV group were prospective studies investigating non-scalpel vasectomy techniques, whereas many of the traditional scalpel studies were retrospective, with a focus on chronic pain and complications of vasectomy. This is the first meta-analysis of the incidence of post-vasectomy pain. The authors found that the incidence of pain was more than double that reported in previous narrative reviews ^[6][7]. They also found that the incidence of pain was markedly higher when using the scalpel approach compared to NSV. The included studies measured chronic pain presenting more than two weeks post-procedure, and were not related to any post-surgical complication such as infection, haematoma, bleeding or incisional pain. There is general agreement in the literature that NSV was a less invasive procedure than traditional incisional vasectomy, the former of which resulted in lower incidences of acute and chronic post-vasectomy pain ^{[8][14][15][16]}. The contraceptive success rates of both procedures were similar as no differences in effectiveness were detected between the two approaches ^[8][17]. There is controversy in the literature regarding the definition of PVPS and subsequently, its reported incidence ^[18]. Different definitions have been used. Davis et al. ^[3] and Leslie et al. ^[9] emphasized intermittent or constant, unilateral or bilateral scrotal pain for a period of more than three months, which interferes with a patient’s daily activities and prompts him to seek medical advice. On the other hand, Sokal et al. ^[15] and Frates et al. ^[13] considered that persistent pain at 2 weeks or more post-vasectomy was sufficient to be deemed long-term or chronic. PVPS was not consistently defined across publications and this may have accounted for the wide variation in reported occurrence (0.4% to 20%). A uniform definition for PVPS and its consistent application would help to determine its true incidence and prevalence in the population. The results from this study suggest that the incidence of PVPS following scalpel and NSV are similar. However, these estimates may not be reliable, due to lack of standardised reporting criteria. Application of the Cochrane Bias tool ^[19] revealed strengths and weaknesses in the design of included studies. Some strengths were that within-study patient cohorts were mostly drawn from similar populations, we could be confident in the assessment of exposure, that the outcome of interest was not present at start of the study and that co-interventions were similar between groups. Shortcomings were that we could not be confident in the assessment of outcome for the majority of studies and the follow-up period was inadequate for five of the eighteen studies. This ereview has are several strengths and limitations. Particular strengths are that the literature was reviewed systematically, risk of bias assessment was used and we followed PRISMA guidelines. All reports of pain were included, not just PVPS, increasing generalisability. Studies that were not written in English were excluded, which may have led to bias. The reporting criteria for pain, and specifically PVPS were not uniformly applied across studies ^{[3][9][15][13]}, making it difficult to accurately estimate the incidences of different types of post-vasectomy pain. Although acute post-surgical complications were discounted by excluding pain outcomes within 2 weeks of the procedure, some other chronic aetiologies such as testicular atrophy, varicoceles, testicular tumours, spermatoceles etc. were not ruled out. Many of the studies did not indicate whether procedures were performed by urologists, primary care doctors, general surgeons or others, which may have affected outcomes. The majority of included NSV studies were of prospective design, whereas many of the scalpel studies were retrospective. Patients who did not have any complications or pain were probably less likely to be seen in follow up or respond to questionnaires in a retrospective study. This may skew the pain results towards the NSV technique. In spite of this possible bias, the authors observed a greater than three-fold increase in pain with the scalpel technique. Other confounding factors include the wide variation in follow-up duration, high heterogeneity and evidence of study bias among studies included in the analysis. Egger’s test revealed the presence of small study effects, or publication bias due to selective reporting and/or dissemination of research findings. Contributing factors may include biases of language, grey/unpublished literature, publication delays, selective exclusion of negative outcomes or citation bias in favour of positive results.

3. Conclusions

The results of this systematic review and meta-analysis indicate that the incidence of post-vasectomy pain is higher than previously reported estimates. Following traditional scalpel vasectomy, the incidence of post-vasectomy pain is more than three-fold higher than after NSV. However, the incidence of PVPS is similar between the two techniques. Therefore, less invasive NSV should be considered as the preferred procedural method compared to the incisional scalpel approach to mitigate the complication of post-vasectomy pain.