The two methods of sperm retrieval most commonly used are penile vibrostimulation (PVS) and the electroejaculation procedure (EEP). PVS is performed using a specialized vibrator placed on the penis to induce reflex ejaculation, whereas EEP uses a rectal probe to deliver electrical current to the periprostatic nerves, eliciting seminal emission. In the first months after injury, semen can only be attained by EEP, since PVS is not effective until spinal shock has resolved.
There are no RCT studies in this area. One of the largest studies of its kind (n=500 men with SCI) (Brackett & Ibrahim 2009) determined that semen could be obtained from most men with SCI without surgical procedures. The studies have mainly reported cumulative ejaculatory success rates and suitability of using techniques such as vibrostimulation, electroejaculation, subcutaneous physostigmine (a reversible acetylcholine esterase antagonist) and operative sperm retrieval for assisted reproduction (Dahlberg et al. 1995; Nehra et al. 1996; Brinsden et al. 1997; Chung et al. 1997; Lochner-Ernst et al. 1997; Le-Chapelain et al. 1998; Hibi et al. 2008; Kanto et al. 2008). Simple prostatic massage alone has been successfully used to obtain sperm in 32% of 69 men with SCI, typically those with lesions above the T10 level (Arafa et al. 2007).
When using PVS, the vibrator parameters of frequency and, in particular, amplitude, have been shown to be important variables to optimize outcomes. The application of a specialized vibrator, with settings of approximately 70-100 Hz with 2.5-3.5 mm amplitude (Brindley 1984; Sønsken et al. 1994; Ohl et al. 1997) on the penis (usually frenulum) produces antegrade, retrograde, and some mixed semen samples. Vibrostimulation worked most reliably in men with lesions above T10, those men with SCI who had a reflex hip flexion with scratching the soles of the feet and with injuries over 6 months in duration (Brindley 1984; Sønsken et al. 1994; Lochner-Ernst et al. 1997; Sønsken et al. 1997) or in patients with incomplete lesions (Taylor et al. 1999). Recent research has shown greater success with PVS in patients less than 3.5 years since injury vs. more than 3.5 years since injury (77% in comparison with 14%: Cechova et al. 2014). A retrospective chart review found that successful ejaculation with PVS was greater when any of the C5–T6 spinal segments was injured (50-67% success) and was less likely when lesions were more caudal (complete L4 injury of 2.6%, 12% when any of the sacral segments was injured: Chehenesse et al. 2016).
Vibrostimulation application for 30 sec to 20 minutes (most occurring in less than 3 min) resulted in ejaculation in 60% to 100% of patients (Beretta et al. 1989; Rawicki & Hill 1991; Sønksen et al. 1994; Rutkowski et al. 1995; Chung et al. 1997; Sønksen et al. 1997). Several recent studies have reported methods to “salvage” some of the ejaculatory failures with PVS. Brackett et al. (2007b) reported success in recovering semen in an additional 22% of men with SCI who failed on several occasions to respond to high amplitude PVS with 1 vibrator, as well as 38% of inconsistent responders, using a technique that sandwiched the glans penis between two vibrators presumably by increasing afferent input. PVS paired with midodrine has mixed results in producing ejaculation in men with SCI. Soler et al. (2007b) reported that 65% of 158 men who failed to respond to PVS alone were able to ejaculate when treated with midodrine (average dose of 18.7 mg) 30-120 minutes prior to applying PVS. They found antegrade ejaculation was more frequent in patients with complete (73%) and UMN (89%) lesions; moderate increases in blood pressure (MAP ~10mmHg) were induced by midodrine in comparison to VS alone, with 13 patients (11 with tetraplegia) recording systolic BP > 200mmHg. Midodrine plus PVS was well-tolerated and salvaged approximately 66% of cases that did not respond to PVS alone (Soler et al. 2007; Courtois et al. 2008). In contrast, a recent double‐blind, randomized, placebo-controlled study found no improvement in ejaculation success rates by PVS combined with midodrine vs. a placebo (Leduc et al. 2015). In a 12‐week, multicenter, double blinded, placebo‐controlled study; 418 men with SCI were randomized to vardenafil (n = 207) or placebo (n = 211) and ejaculation success was assessed using the International Index of Erectile Function (IIEF). The results of this study showed a significantly greater ejaculation success rate with vardenafil when compared to placebo (19% vs. 10%) (Giuliano et al. 2008).
When vibrostimulation fails, obtaining semen by electroejaculation (Taylor et al. 1999) is a possibility, particularly for people with lower lesions (Ohl et al. 2001). Since an ejaculate was almost always attainable by penile vibratory stimulation or electroejaculation, the need for surgical aspiration was rare but reported (Dahlberg et al. 1995; Lochner-Ernst et al. 1997; Shieh et al. 2003). Retrograde ejaculation of semen into the bladder, which frequently accompanies EEP and affects sperm quality, can be prevented by simply applying a technique of gentle bladder neck tamponade (Lim et al. 1994) using a non-toxic all-silicone Foley catheter and the balloon filled with 10mls of saline. Controlling severity of autonomic dysreflexia with nifedipine allowed for better sperm retrieval using electroejaculation technique (VerVoort et al. 1988; Lucas et al. 1991; Brackett et al. 2002; Elliott & Krassioukov 2006). Electroejaculation is considered more invasive and painful than penile vibratory stimulation for men with incomplete SCI, and patients prefer penile vibratory stimulation if sperm quality was equal between the two techniques (Ohl et al. 1997). Vibrostimulation has been shown to also induce pronounced levels of autonomic dysreflexia (Sheel et al. 2005; Claydon et al. 2006), especially in men with tetraplegia with increases of +70-90mmHg in mean arterial pressure (SBP ~190±20mg, DBP ~130±10mg, SBP ~150±10mg), reduced heart rate (–5-10 bpm) and cardiac arrhythmias. This requires careful monitoring during vibratory stimulation and screening for safe home use as AD was often silent in nature.
The use of physostigmine injections alone or in conjunction with both vibrostimulation and electroejaculation has largely dropped out of use since the mid-1990s (Chapelle et al. 1983; Leduc et al. 1992). An implantable hypogastric nerve stimulator (radio-controlled) was also successful in yielding semen with sperm (not necessary all motile), but has not undergone further development (Brindley et al. 1989).
Operative sperm retrieval should be reserved for those men who fail conservative sperm retrieval methodology. Operative retrieval commits a couple to expensive higher-level interventions such as intracytoplasmic sperm injection (ICSI), where a single sperm is injected directly into the egg to force fertilization. Such high level interventions with operative sperm retrieval, i.e. using fresh testicular sperm (Kanto et al. 2008) or aspirated retrograde vasal sperm (Hibi 2008) in an ICSI cycle, do result in better conception rates per cycle from the male SCI population. However, decisions regarding method of retrieval and insemination must also include a cost benefit ratio (Ohl et al. 2009).
There is level 4 evidence (Beretta et al. 1989; Sønksen et al. 1994; Le Chapelain et al. 1998; Brackett et al. 2007b, 2009; Kathiresan et al. 2012; Qiu et al. 2012; Sønksen et al. 2012) that semen retrieval may be assisted by vibrostimulation in men with lesions above T10.
There is level 4 evidence (Soler et al. 2007b) that Midodrine may be an effective and safe adjunct to penile vibratory stimulation in men not responding to penile vibratory stimulation alone who are not at risk for significant autonomic dysreflexia.
There is level 4 evidence (Brindley 1984; Halstead et al. 1987; Ohl et al. 1989; Lochner-Ernst et al. 1997; Le Chapelain et al. 1998; Kolettis et al. 2002) that semen retrieval may be assisted by electroejaculation in men who failed vibrostimulation.
There is level 4 evidence (Brindley et al. 1989) that surgical aspiration may be used to retrieve sperm if vibrostimulation and electroejaculation are not successful.
There is level 4 evidence (Arafa et al. 2007) that prostatic massagethru the rectum to push the sperm out through the ejaculatory ductal system is one technique to retrieve semen in some men and is more successful with lesions above T10.
There is level 4 evidence (Lim et al. 1994) that the use of a balloon catheter to tamponade the bladder neck may be effective in obtaining antegrade samples in men who normally deliver retrograde samples.
There is level 4 evidence (Hibi et al. 2008) that retrograde vasal sperm aspiration can retrieve sperm of sufficient motility to afford pregnancy.
There is level 3 evidence (Kanto et al. 2008) that testicular sperm extraction followed by intracytoplasmic injection is an effective way to induce pregnancy, with fresh sperm giving better results than frozen-thawed sperm.