Selective use of percutaneous testis biopsy to optimize IVF-ICSI outcomes: a case series

The sperm-related factors that result in limited fertilization, poor embryo development, impaired implantation, and early spontaneous abortion are poorly understood. Historically, sperm motility and morphology have been the primary surrogates for sperm quality; early studies substantiated this concept in terms of poorer male factor-related outcomes using IVF with conventional insemination [15–17]. However, the predictive values of morphology and motility have been questioned when the standard insemination process is bypassed [18, 19]. In an effort to better characterize sperm quality in the era of IVF-ICSI, investigations into more sophisticated measures of sperm quality such as oxidative damage and impaired DNA integrity have been pursued.

A relationship between oxidative stress and subfertility has now been established. Elevated seminal ROS are negatively correlated with sperm concentration, motility, and morphology [20, 21]. Additionally, elevated ROS are found in men who have undergone vasectomy reversal [22]. Cases 2 and 4 are characterized by OAT in men who were previously treated with vasovasostomy. It is unclear if elevated ROS played a dominant role in these cases, although their presentations can be considered consistent with oxidative stress.

A direct link between sperm oxidative damage and embryo demise has been demonstrated in animal models [23]. Additionally, elevated seminal ROS are correlated with poor embryo development in humans [24]. Relatively little is known regarding the accumulation of oxidative damage as sperm progress through the male reproductive tract. Ollero et al. postulated that the presence of immature spermatozoa, a known source for endogenous ROS [25], may result in damage to mature sperm during transit through the epididymis [26]. The local environment within the epididymis may be further stressed as a vasovasostomy site begins to stenose. As pressure builds within the testicular side of the anastomosis, progressive epididymal dysfunction may ensue, particularly in a system that has suffered iatrogenic obstruction in the past [27]. The use of testicular sperm may bypass this potentially toxic local environment, and may translate into improved IVF-ICSI outcomes in patients with similar profiles as Cases 2 and 4.

A known result of oxidative stress is DNA damage, which is a prominent feature of Cases 1 and 4. For both patients an SCSA revealed a DFI above 40 %. In one of the largest series by Bungum et al., a DFI greater than 30 % was found to translate into an odds ratio of 0.1 (CI 0.02 – 0.42) for clinical pregnancy rates following intrauterine insemination [28]. Their data found no statistical difference for their conventional IVF and IVF-ICSI cohorts, which was initially attributed to selection bias regarding oocyte quality. A subsequent meta-analysis corroborated these findings regarding IVF-ICSI and an elevated DFI, although a trend toward a higher miscarriage rate was noted [29]. Despite the fact that IVF-ICSI outcomes remain favorable even in states of marked DNA damage [30], conceivably due to the DNA repair capacity of high quality oocytes [31], the possibility remains that a subset of patients may be particularly affected by an elevated DFI. Greco and colleagues examined a small cohort of couples who were similar to Case 1: patients who were characterized by an elevated DFI and recurrent IVF-ICSI failure using ejaculated sperm [11]. They found that testis-derived samples had significantly less DNA damage. Although fertilization rates and embryo development were no different in the testis versus ejaculated samples, the testicular sperm achieved eight clinical pregnancies as opposed to one in the control group. They postulated that significant DNA damage accrues during transit though the epididymis, similar to the concept raised by Ollero et al. [26].

Some investigators have attempted to treat impaired DNA integrity with antioxidants in order to limit oxidative stress. Abad et al. demonstrated a modest improvement in semen parameters and DFI following 3 months of oral antioxidant therapy in a group of infertile men [32]. In the case of testicular derived sperm, a small case series by Greco et al. found improved ICSI outcomes when men with poor DNA integrity are pretreated with oral antioxidants [33]. A summative review by Kumalic and Pinter substantiated the beneficial effects of antioxidant therapy, albiet most of these results are based upon ejaculated samples [34]. In our practice we routinely offer men with asthenospermia supplementation with coenzyme Q10. It remains unclear if the outcomes would have differed if the men in this case series were offered a formal course of antioxidant therapy. Further studies are needed to expand upon the preliminary results of Greco et al., in which testicular sperm may be further optimized through oral antioxidants [33].

In regards to Case 3, little is known about the pathophysiology of poor IVF-ICSI outcomes in Kartagener’s Syndrome. Given the rarity of the disease, most of the primary literature is based upon case reports [35]. It is assumed that Kartagener’s Syndrome results in longer transit times through the epididymis, which may result in greater oxidative damage, cell senescence, and loss of DNA integrity [36, 37]. An analysis by Cayan et al. demonstrated substantial improvement of sperm viability with testicular sperm in one patient, presumably bypassing the damage that may develop within the epididymis [38]. Additionally, Westlander and colleagues concluded that more reliable fertilization rates can be achieved with testicular sperm [37]. Future studies are needed to define a link between this rare syndrome and elevated oxidative stress and/or increased DNA fragmentation.

The optimal source of sperm for IVF-ICSI remains controversial [11, 39]. Two recent series have compared the results of IVF-ICSI between ejaculated and testicular sperm. Lu et al. found a slight advantage of ejaculated sperm in terms of fertilization rates and embryo quality within one center’s large experience [4]. Similarly, Gnoth and colleagues analyzed 337 IVF-ICSI cycles and found no difference in clinical outcomes between ejaculated and testicular sperm for men with cryptozoospermia [6]. Both studies were limited by a retrospective design with significant potential for selection bias. In each case a testicular sperm extraction was used only when sperm could not be reliably found within the ejaculate. Neither study compared IVF-ICSI outcomes between ejaculated and matched testicular derived sperm from the same individual. Additionally, these studies did not stratify for the cohort of men who have had repeated IVF-ICSI failure, a group that may benefit from testis-derived sperm [10, 11, 40, 41]. Our small case series documents a possible benefit for this population. It should be noted, however, that our study is also limited by a retrospective design. Additionally, the criteria used to select for PercBx was not standardized at our institution, and so one must consider a component of selection bias. Despite these limitations in study design, our data do suggest an indication for retrieving testicular sperm despite sperm availability within the ejaculate. Further studies are needed to confirm our observations.