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Sperm toxicity of “nonspermicidal” lubricant and ultrasound gels used in reproductive medicine

2010; Elsevier BV; Volume: 95; Issue: 2 Linguagem: Inglês

10.1016/j.fertnstert.2010.09.011

1556-5653

Josefina Vargas, Michel Crausaz, A. Senn, Marc Germond,

Ovarian function and disorders

Three commercial, nonspermicidal gels used in fertility practice were found to be toxic to sperm in a 24-hr sperm survival assay; these included Felis, Replens, and Aquasonic Gel, which is used for transvaginal ultrasound during ovulation monitoring. In contrast, Pre-Seed did not cause any sperm toxicity, suggesting its appropriate use by patients who are trying to conceive, as well as clinicians during fertility procedures. Three commercial, nonspermicidal gels used in fertility practice were found to be toxic to sperm in a 24-hr sperm survival assay; these included Felis, Replens, and Aquasonic Gel, which is used for transvaginal ultrasound during ovulation monitoring. In contrast, Pre-Seed did not cause any sperm toxicity, suggesting its appropriate use by patients who are trying to conceive, as well as clinicians during fertility procedures. During human reproduction, spermatozoa (sperm) deposited in the vagina migrate through the cervix and uterus to reach the oocyte in the fallopian tube. Human sperm are capable of surviving exposure to unfavorable environmental conditions, such as those in the vagina, provided their motility remains unaffected. Sperm transport through the female genital tract is optimal at a pH of 7.0–8.4 (1World Health OrganizationWHO laboratory manual for the examination of human semen and sperm-cervical mucus interaction.4th ed. Cambridge University Press, Cambridge1999Google Scholar), whereas pH levels 400 mOsm/kg (2Rossato M. Balercia G. Lucarelli G. Foresta C. Mantero F. Role of seminal osmolarity in the regulation of human sperm motility.Int J Androl. 2002; 25: 230-235Crossref PubMed Scopus (48) Google Scholar). Lubricant gels are used to relieve vaginal dryness for comfort during intimacy and in the clinic to facilitate insertion of medical devices. Ultrasound gel is used during transvaginal ovarian echography, to act as a lubricant for the introduction of the transducer probe and as a transmitter of ultrasound waves. Many commercial lubricant and ultrasound gels contain traditionally harmless ingredients such as glycerin (glycerol) or propylene glycol. Because they do not contain chemical spermicides, they are often labeled as nonspermicidal. Most of these gels have pH levels 1,000 mOsm/kg, making them suboptimal for sperm function (3Agarwal A. Deepinder F. Cocuzza M. Short R.A. Evenson D.P. Effect of vaginal lubricants on sperm motility and chromatin integrity: a prospective comparative study.Fertil Steril. 2008; 89: 375-379Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar). In fact, studies have shown that lubricants and ultrasound gels can have a toxic effect on sperm and are contraindicated for couples who are trying to conceive (3Agarwal A. Deepinder F. Cocuzza M. Short R.A. Evenson D.P. Effect of vaginal lubricants on sperm motility and chromatin integrity: a prospective comparative study.Fertil Steril. 2008; 89: 375-379Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar, 4Kutteh W.H. Chao C.H. Ritter J.O. Byrd W. Vaginal lubricants for the infertile couple: effect on sperm activity.Int J Fertil. 1996; 41: 400-404Google Scholar, 5Anderson L. Lewis S.E.M. McClure N. The effects of coital lubricants on sperm motility in vitro.Hum Reprod. 1998; 13: 3351-3356Crossref PubMed Scopus (48) Google Scholar, 6Shimonovitz S. Yagel S. Zacut D. Ben Chetrit A. Ever-Hadani P. Har-Nir R. et al.Ultrasound transmission gel in the vagina can impair sperm motility.Hum Reprod. 1994; 9: 482-483PubMed Google Scholar). The reported sperm-toxic effects of gels are related to dose and duration of exposure, but previous studies have primarily used concentrations of gels (>10%), which may not reflect the levels sperm would encounter in the vagina after ejaculation. The toxic properties of substances coming into contact with human sperm can be screened using a 24-hour sperm survival assay (7Claassens O.E. Wehr J.B. Harrison K.L. Optimizing sensitivity of the human sperm motility assay for embryo toxicity testing.Hum Reprod. 2000; 15: 1586-1591Crossref PubMed Scopus (40) Google Scholar). To optimize the sensitivity of this test, albumin products should be removed from the culture medium, so as not to mask deleterious aspects of test solutions. This bioassay provides a sperm motility index (SMI) calculated by dividing the percent of progressively motile sperm in the test solution by that in control solution at specific times. SMI values <0.75 are predictive of poor assisted reproduction outcomes and indicate sperm toxicity (7Claassens O.E. Wehr J.B. Harrison K.L. Optimizing sensitivity of the human sperm motility assay for embryo toxicity testing.Hum Reprod. 2000; 15: 1586-1591Crossref PubMed Scopus (40) Google Scholar). The isotonic, pH-neutral lubricant (Pre-Seed Luricant; INGfertility, Valleyford, WA) has indications of use as being safe for couples who are trying to conceive. An initial study showed no effect of Pre-Seed on sperm motility in 30-min cultures (3Agarwal A. Deepinder F. Cocuzza M. Short R.A. Evenson D.P. Effect of vaginal lubricants on sperm motility and chromatin integrity: a prospective comparative study.Fertil Steril. 2008; 89: 375-379Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar). However, albumin was included in this study, thereby decreasing the sensitivity of the assay. The purpose of this study was to compare sperm toxicity of four commercial nonspermicidal gels, using an albumin-free, 24-hour human sperm survival assay and low concentrations of the gels (<10%) to better reflect proposed in vivo exposure. Fresh, normospermic semen samples were obtained from donors and analyzed according to the World Health Organization guidelines (1World Health OrganizationWHO laboratory manual for the examination of human semen and sperm-cervical mucus interaction.4th ed. Cambridge University Press, Cambridge1999Google Scholar). Institutional review board approval was obtained from the FABER Foundation Scientific Board. A computer-assisted semen analyzer (CASA; Microptic, Barcelona, Spain) assessed sperm concentrations and motility using 20-μm–deep counting chambers (Leja Products, Nieuw-Vennep, The Netherlands). Semen samples were washed through density gradients (Spermfilter; NMS Biomedical, Praroman, Switzerland) and motile sperm pellets washed twice with human tubal fluid (HTF) medium (Irvine Scientific, Santa Ana, CA) plus 10% Synthetic Serum Supplement (Irvine Scientific). Final pellets of sperm were pooled from three to five donors, as previously validated (7Claassens O.E. Wehr J.B. Harrison K.L. Optimizing sensitivity of the human sperm motility assay for embryo toxicity testing.Hum Reprod. 2000; 15: 1586-1591Crossref PubMed Scopus (40) Google Scholar), and resuspended in HTF to achieve sperm concentrations of 10–20 million/ml. Test solutions included HTF with four different concentrations (0.10%, 1.0%, 5.0%, and 10%) of each of the following: Pre-Seed Lubricant, Felis Lubricant (Lagap SA, CH-6943; Vezia, Switzerland), Replens Vaginal Moisturizer (Vifor SA; Villars-sur-Glâne, Switzerland), and Aquasonic Ultrasound Gel (Parker Labs, Fairfield, NJ), in 0.5-mL volumes equilibrated for 1.5 hours in 5% CO2 and 95% humidity in a 37°C incubator. The osmolality of each test solution was determined by the freezing-point method (Micro Osmometer Model 3300; Advanced Instruments, Norwood, MA). A 100-μL aliquot of pooled sperm sample was added to each of the 0.5-mL test solutions, resulting in final gel concentrations (v/v) of 0.083%, 0.830%, 4.150%, and 8.300%. The 0.083% solution was assigned as the control for each gel, based on low concentrations of gel, and the consistent handling across all treatments. At 0, 1, and 24 hours of incubation, 5-μL samples from each solution were evaluated in triplicate for percent progressively motile sperm and solution pH. The pH was measured using indicator paper (Merck 1.09557.0003; Merck, Whitehouse Station, NJ). Sperm toxicity of test solutions was determined using the SMI to compare percent motility in each test solution to that in the control solution at 1 and 24 hours (Table 1). SMI values <0.75 indicated sperm toxicity, as previously reported (7Claassens O.E. Wehr J.B. Harrison K.L. Optimizing sensitivity of the human sperm motility assay for embryo toxicity testing.Hum Reprod. 2000; 15: 1586-1591Crossref PubMed Scopus (40) Google Scholar). The experiment was replicated three times, and means ± SD were used in a chi-square analysis to compare the SMI observed in each gel.Table 1SMI values following 1 or 24 hours of incubation as a ratio of percent sperm motility in culture with 8.33% gel over percent sperm motility in controls (0.083% gel).Lubricant gels1 h24 hAquasonic1.130.54Felis1.110.52Pre-Seed1.050.93Replens0.030.12Note: Boldface text denotes SMI <0.75, indicating sperm-toxicity. Open table in a new tab Note: Boldface text denotes SMI 0.05), supporting the use of the 0.083% solution as the control. During the 24-hr assay, Aquasonic, Felis, and Replens caused declines (P<0.05) in mean percent motile sperm, resulting in SMI values <0.75 (Table 1) and a designation of sperm toxic. Loss of sperm motility was seen with Replens, even at the 0.83% concentration. In contrast, sperm motility did not decrease with Pre-Seed, indicating a lack of sperm toxicity for this gel. These data confirm that even gels labeled nonspermicidal can significantly impair sperm motility, and at lower concentrations than previously reported (<10%). It is unlikely that safe concentrations of Aquasonic, Felis, and Replens can be determined reliably. Of the products evaluated, only Pre-Seed was not toxic to sperm. The American Society for Reproductive Medicine Practice Committee consensus guideline Optimizing Natural Fertility urges physicians to discuss the importance of lubricant choice for couples who are trying to conceive (8Practice Committee of American Society for Reproductive MedicineOptimizing natural fertility.Fertil Steril. 2008; 90: S1-S6PubMed Google Scholar). Reduced sperm motility following gel contact has been thought to be due to shifts in pH, osmolality changes, or both (3Agarwal A. Deepinder F. Cocuzza M. Short R.A. Evenson D.P. Effect of vaginal lubricants on sperm motility and chromatin integrity: a prospective comparative study.Fertil Steril. 2008; 89: 375-379Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar, 4Kutteh W.H. Chao C.H. Ritter J.O. Byrd W. Vaginal lubricants for the infertile couple: effect on sperm activity.Int J Fertil. 1996; 41: 400-404Google Scholar, 5Anderson L. Lewis S.E.M. McClure N. The effects of coital lubricants on sperm motility in vitro.Hum Reprod. 1998; 13: 3351-3356Crossref PubMed Scopus (48) Google Scholar). This study found that even in treatments without large changes in pH or osmolality, sperm toxicity was observed. A direct toxic effect of ingredients cannot be ruled out. Both Replens and Felis contain glycerin (Aquasonic does not list ingredients). Pre-Seed alone in this study is known to not contain glycerin. Glycerin penetrates across sperm membranes and even at low concentrations (e.g., 2%) can disrupt cell function and motility (9Tulandi T. McInnes R.A. Vaginal lubricants: effect of glycerin and egg white on sperm motility and progression in vitro.Fertil Steril. 1984; 41: 151-153Abstract Full Text PDF PubMed Scopus (18) Google Scholar, 10Gilmore J.A. McGann L.E. Liu J. Gao D.Y. Peter A.T. Kleinhans F.W. et al.Effect of cryoprotectant solutes on water permeability of human spermatozoa.Biol Reprod. 1995; 53: 985-995Crossref PubMed Scopus (188) Google Scholar). Aquasonic Gel is commonly used for vaginal ultrasound examination to monitor follicle development before intercourse or insemination. Based on sperm toxicity found in this study and others (6Shimonovitz S. Yagel S. Zacut D. Ben Chetrit A. Ever-Hadani P. Har-Nir R. et al.Ultrasound transmission gel in the vagina can impair sperm motility.Hum Reprod. 1994; 9: 482-483PubMed Google Scholar), this gel should not be used for transvaginal procedures in fertility patients. Labeling of gels as nonspermicidal does not ensure that a product will not impair sperm function. Even low concentrations (<10%) of gels in this study were toxic to sperm and interfered with their motility. Among the gels evaluated, only Pre-Seed did not show any sperm toxicity, making it the most appropriate lubricant choice for women who are trying to conceive or for use during clinical procedures, including vaginal insertion of diagnostic and therapeutic probes.