Intermittent catheters (ICs) are the mainstay of treatment for individuals with bladder voiding difficulties, such as patients with spinal cord injury (SCI) or bladder outflow obstructions. ICs with hydrophilic coatings were introduced in the 1980s. The use of hydrophilic-coated ICs has greatly improved the user experience and quality of life, when compared to uncoated ICs. Hydrophilic coatings absorb water resulting in a hydrated and lubricious surface, which eases catheter insertion. However, these coatings contain polyvinylpyrrolidone (PVP), which upon dry out, leads to a sticky catheter surface which can increase coating delamination from the catheter surfaces (1). Moreover, associated problems experienced on catheter removal, such as pain and urethral microtrauma, can have an adverse effect on the patient's quality of life.
SCI patients have been reported to be predisposed to infertility issues such as decreased sperm motility (2). PVP is used within intracytoplasmic sperm injection (ICSI) as it is known to decrease the motility of spermatozoa (3). It is therefore theorised that coated ICs may deposit PVP in a patient’s urethra resulting in sperm being exposed to residual PVP, which may affect motility and/or viability. This is an area lacking in detailed research with limited studies to date (2). 
It was hypothesised that higher concentrations of PVP will negatively impact spermatozoa motility and/or viability.

Spermatozoa viability
Concentrations of PVP (molecular weight 360,000 (K90); 0–16% w/v) dissolved in phosphate buffered saline (PBS) were prepared. Porcine semen (Deer Park, Gloucester Old Spot, Reg No R012707GS UKPO5) diluted 1:4 with an antimicrobial extender (53.3% penicillin, 26.7% polymyxin E, 13.3% kanamycin and 20% neomycin) were heated to 37 °C and exposed to varying concentrations of PVP solution for 15 minutes. Spermatozoa was stained with 0.4% Trypan Blue Solution and images captured at random fields of view (EVOS™ M5000 Imaging System). Spermatozoa viability was determined as the percentage of live cells in a sample image, based on dye exclusion. Sperm cells with a damaged plasma membrane will stain blue, whilst viable cells will not be stained. ImageJ particle analyser was used to quantify viable and non-viable cells.

Spermatozoa motility
Porcine semen was heated to 37 °C and exposed to concentrations of PVP (0–16% w/v) solution for 1 h. Following exposure, videos of spermatozoa were captured at random fields of view. The motility of spermatozoa (µm/sec) were assessed by ImageJ software by measuring the distance travelled by spermatozoa per second.

Based on a one-way ANOVA, 12 replicate samples allowed for a 10% difference between sperm motility and viability with and without exposure to PVP to be determined.

Preliminary spermatozoa motility data (Figure 1) illustrates a negative correlation between spermatozoa motility and increasing PVP concentration. Significant decrease in spermatozoa motility was observed in samples exposed to >6% w/v PVP, with motility falling to < 20.25 µm/sec ± 1.56. However, sperm motility of >25 µm/sec is considered desirable for fertility (3). Most notably, no motility was detected in spermatozoa exposed to 16% w/v PVP. 

In relation to spermatozoa viability, Figure 2 highlighted that spermatozoa viability fell below 90% when exposed to PVP concentrations >12% w/v.

There was a marked reduction in spermatozoa motility is significantly decreased in samples exposed to >6% w/v PVP, relative to control PBS solution. Furthermore, samples exposed to 16% w/v PVP exhibited no motility. Further work should be conducted to ascertain whether a reduction in spermatozoa motility has clinical ramifications for IC users.

PVP may have cytotoxic potential, particularly at higher concentrations as there was a significant decrease in cell viability in spermatozoa exposed to >10% w/v PVP concentrations relative to control PBS solution. This may have clinical ramifications for PVP-coated ICs, particularly if they are exposed to PVP over a prolonged period of time.

In summary, exposure to PVP was found to negatively affect spermatozoa motility and viability. Findings from this work therefore suggest that PVP coatings may have the potential to impact fertility. Future studies should be conducted to develop upon this preliminary work and assess the long-term clinical impact of repeated use of PVP-coated ICs.

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Auger J, Rihaoui R, François N, Eustache F. Effect of short-term exposure to two hydrophilic-coated and one gel pre-lubricated urinary catheters on sperm vitality, motility and kinematics in vitro. Minerva Urol Nefrol. 2007;59(2):115-24.
Kato Y, Nagao Y. Effect of polyvinylpyrrolidone on sperm function and early embryonic development following intracytoplasmic sperm injection in human assisted reproduction. Reprod Med Biol. 2012;11(4):165-176.