Varicoceles are present in approximately 15% of men in the general population, in 34%–45% of patients with primary infertility, and in 45%–81% of patients with secondary infertility [1]. However, some studies have reported comparable rates of clinically palpable varicoceles in fertile and infertile men, with approximately 80% of men with varicoceles being fertile [2,3]. Therefore, selected patients may benefit from varicocele surgery. According to European Association of Urology guidelines, surgery is recommended for infertile men with a clinical varicocele, abnormal semen parameters, and otherwise unexplained infertility in couples where the female partner has a good ovarian reserve [4].

Abnormal sperm morphology frequently coexists with impaired concentration and motility. Isolated teratozoospermia is reported in approximately 12% of infertile men [5]. Recent studies have shown that oxidative stress is associated with increased sperm DNA fragmentation (SDF) and abnormal sperm chromatin condensation, features commonly observed in men with isolated teratozoospermia. Furthermore, some studies have suggested an association between teratozoospermia and apoptosis [6,7]. The detrimental effects of oxidative stress on sperm parameters have led to the use of antioxidants in the treatment of male subfertility [8].

The literature presents inconsistent findings regarding the impact of teratozoospermia on pregnancy outcomes and the success of assisted reproductive technologies [9-11]. The simultaneous presence of isolated teratozoospermia and clinical varicoceles is uncommon. Consequently, few studies have evaluated the role of varicocele surgery in patients with isolated teratozoospermia [12-16]. However, these studies were all retrospective and often included small sample sizes, limiting the precision of their findings. Therefore, this prospective randomized study aims to assess the effectiveness of varicocele surgery versus male infertility supplements in managing male infertility associated with clinical varicoceles and isolated teratozoospermia. To the best of our knowledge, this is the first randomized controlled trial to investigate the role of varicocele surgery in cases of isolated teratozoospermia.

This multicenter, randomized comparative study was conducted at two tertiary centers between January 2022 and January 2024. Men with infertility, clinical varicoceles, and isolated teratozoospermia were randomly assigned (non-blinded, using the closed envelope method) into two groups: group A (varicocele ligation) and group B (male infertility supplements). Randomization was independent of the patients’ clinical parameters.

Male patients with a 1-year history of subfertility and clinically palpable varicocele associated with isolated teratozoospermia (defined as <4% normal forms with otherwise normal sperm parameters) were included in the study. Exclusion criteria included patients with a total testosterone level less than 12 nmol/L, subclinical varicoceles, recurrent varicoceles, other causes of male factor infertility, a body mass index ≥30 kg/m², concurrent female factor infertility, or a female partner aged over 40 years.

Patients were referred to our fertility unit if two semen analyses demonstrated abnormal semen parameters according to the 2021 World Health Organization criteria [17]. Morphological abnormalities were reported based on head, midpiece, and tail defects. Detailed histories were obtained from all patients, including duration of infertility, age of the female partner, smoking history, and relevant medical, surgical, and medication histories. Genital examinations were performed in both supine and standing positions. All patients underwent serum hormonal profiling (including morning fasting total testosterone, follicle-stimulating hormone, luteinizing hormone, and, when indicated, prolactin and thyroid hormones) and ultrasonographic scans of both testes.

Semen samples were used to measure SDF using the sperm chromatin dispersion method, commonly known as the halo test [18]. This test is based on the principle that sperm with fragmented DNA fail to produce the characteristic halo of dispersed DNA loops—observed in sperm with intact DNA—following acid denaturation and removal of nuclear proteins. DNA fragmentation was further confirmed using the DNA breakage detection-fluorescence in situ hybridization method. The percentage of spermatozoa with abnormal chromatin structure (i.e., the ratio of single-stranded [denatured] DNA to total DNA) was defined as the SDF, with values above 20% considered abnormal [19]. The semen samples were all analyzed by the same embryologists.

Varicocele ligation was performed by a single surgical team using microsurgical subinguinal varicocelectomy under spinal anesthesia. All procedures followed standard surgical techniques and were conducted with a Karl Zeiss operating microscope at magnifications ranging from 10× to 20× [20]. Patients in group B were prescribed male fertility supplements consisting of a single tablet containing L-carnitine (1 g), vitamin C (1 g), and vitamin E (400 mg) daily for 6 months. All patients were advised to lose weight and to avoid smoking, excessive heat exposure to the testicles, and wearing tight clothing.

Repeat semen analysis and SDF measurement were performed 4 months after surgery or medical treatment. The pregnancy rate was then assessed at 12 months. The study outcome measures were:

(1) The percentage of improvement in sperm morphology (>4% normal forms) and SDF for the two groups.

(2) Spontaneous pregnancy rates at the 12th month.

The study was approved by the local ethics committee of South Valley University (URO016/639) and was conducted in accordance with the Declaration of Helsinki. Written Informed consent was obtained from all patients.

Between January 2022 and January 2024, 90 patients with isolated teratozoospermia and clinical varicoceles were recruited. Nine patients either missed follow-up or declined participation and opted for in vitro fertilization (IVF), leaving 81 patients who completed the study—40 in group A and 41 in group B (Figure 1). Primary infertility was present in 62 patients (77.5%), while 18 patients (22.5%) had secondary infertility. Baseline characteristics were comparable between the two groups (Table 1).

In the varicocele ligation group, the percentage of normal sperm morphology increased from 1.2±0.88 to 3.2±1.86 (p<0.001). In the antioxidant group, morphology improved from 1.2±0.99 to 2.05±1.96 (p=0.001). Similarly, SDF values decreased from 25.4±6.5 to 16.28±5.93 in the varicocele ligation group and from 26.2±10.31 to 22.43±10.79 in the antioxidant group (p<0.001 for both groups). Although improvements in sperm parameters and SDF were observed in both groups, the magnitude of improvement was greater in the varicocele ligation group (Table 2).

More patients in the varicocele ligation group achieved normal sperm morphology, with 19 patients (47.5%) compared to 11 patients (27.5%) in the antioxidant group (p=0.06). Additionally, the natural pregnancy rate was higher in the varicocele ligation group, with nine patients (22.5%) achieving pregnancy compared to five patients (12.5%) in the antioxidant group; however, this difference did not reach statistical significance (p=0.23).

Univariate analysis identified the presence of pinpoint and round head abnormalities as unfavorable preoperative factors for improvement in normal sperm morphology, with statistical significance. Multivariate analysis confirmed that pinpoint and round head abnormalities were significantly associated with poorer outcomes following varicocele ligation (relative risk, 0.14; 95% confidence interval, 0.001 to 0.236; p=0.003) (Tables 3 and 4).

This study demonstrated that both varicocele surgery and oral antioxidant supplementation improved sperm parameters, SDF, and the natural pregnancy rate in subfertile men with clinically palpable varicoceles and isolated teratozoospermia. However, microsurgical subinguinal varicocelectomy resulted in a superior improvement. Additionally, the presence of pinpoint and round head abnormalities was associated with significantly poorer outcomes.

There are conflicting findings regarding the impact of teratozoospermia on pregnancy rates. Spiessens et al. [9] reported that isolated teratozoospermia decreases both the spontaneous pregnancy rate and the success rates of intrauterine insemination (IUI) and IVF. Conversely, Lee et al. [10] demonstrated significantly different pregnancy outcomes following IUI in patients with sperm morphology greater than 4%. Hence, advanced techniques such as intracytoplasmic morphology-selected sperm injection have been recommended for patients with isolated teratozoospermia. In contrast, Kovac et al. [11] found that 30% of their patients achieved natural pregnancy despite having 0% normal morphology, with a median follow-up of 2.5 years.

Few studies have investigated the role of varicocelectomy in improving sperm morphology. Cakiroglu et al. [16] reported that varicocelectomy did not enhance sperm morphology; however, this study was limited by a small sample size and a follow-up period of only 6 months, and it did not report pregnancy outcomes. In contrast, Cakan et al. [15] demonstrated an improvement in sperm morphology following microscopic varicocele surgery compared to controls, with a natural pregnancy rate of 17.8%.

Other studies have reported similar positive effects of varicocele surgery on isolated teratozoospermia. Choe and Seo [13] found a statistically significant improvement in sperm morphology following varicocelectomy, with 21 patients (31.3%) exhibiting normal sperm morphology; however, pregnancy outcomes were not evaluated. Similarly, Ilktac et al. [14] observed significant improvements in sperm morphology after surgery, with higher natural pregnancy rates among men with normal morphology or low rates of head abnormalities. Furthermore, a recent retrospective study reported that sperm parameters, SDF, and pregnancy rates were significantly higher after microscopic varicocelectomy compared to male fertility supplements, with a natural pregnancy rate of 30.5% at 12 months [12].

The results of our study are consistent with the literature. In our cohort, the natural pregnancy rate was 22.5% at 12 months following microscopic varicocelectomy. Moreover, analysis of predictive factors revealed that sperm head abnormalities were associated with poorer outcomes, which aligns with previous findings indicating that sperm head abnormalities negatively predict pregnancy rates [14].

Varicoceles can impair sperm parameters by increasing SDF and reactive oxygen species. A recent study demonstrated that men with isolated teratozoospermia exhibit significantly higher levels of single-sperm DNA breaks, oxidative stress, and apoptosis compared to controls [7]. Some studies have reported reductions in these factors following varicocele surgery [21,22]. Conversely, only a few studies have evaluated the use of antioxidants to counteract the effects of varicoceles on sperm parameters. Moslemi and Tavanbakhsh [23] demonstrated that daily administration of vitamin E and selenium improved all sperm parameters in 52% of 690 infertile men. Additionally, a randomized controlled trial involving 56 infertile men found that L-carnitine supplementation was significantly associated with improvements in all sperm parameters, particularly sperm motility [24]. Fathi et al. [12] reported that both varicocelectomy and oral antioxidants reduced SDF and improved sperm morphology; however, the improvement was significantly greater in the varicocelectomy group. Notably, the European Academy of Andrology guidelines remain neutral regarding the use of antioxidants in oligoasthenoteratospermia [25].

This study offers several advantages. It is the first randomized controlled trial to evaluate improvements in sperm morphology, SDF, and natural pregnancy rates in this patient population. Furthermore, we analyzed predictive factors for improvement following microscopic varicocelectomy. However, the study is limited by its small sample size and relatively short follow-up duration.

In conclusion, our findings suggest that varicocelectomy is more effective than antioxidant supplementation in achieving natural pregnancy. Therefore, varicocelectomy should be considered a viable treatment option for infertile men with isolated teratozoospermia and clinically palpable varicoceles.