Pre-ejaculate

Pre-ejaculate on the glans of a circumcised penis

Pre-ejaculate (also known as pre-ejaculatory fluid, pre-seminal fluid, or Cowper's fluid, and colloquially as pre-cum) is the clear, colorless, viscous fluid that is emitted from the urethra of the penis during sexual arousal. It is similar in composition to semen but has some significant chemical differences. The presence of sperm in the fluid is variable. Research has found low levels of or no sperm in pre-ejaculate, though these existing studies examined small samples of men.[1][2][3] Two contrary, yet non-generalizable studies that found mixed evidence, including individual cases of a high sperm concentration, were published in 2011 and 2016.[4][5] Pre-ejaculate is believed to function as a lubricant and an acid neutralizer.

Origin and composition

The fluid is discharged during arousal, masturbation, foreplay or at an early stage during sexual intercourse, some time before the person fully reaches orgasm and semen is ejaculated. It is primarily produced by the bulbourethral glands (Cowper's glands), with the glands of Littre (the mucus-secreting urethral glands) also contributing.[6]

The amount of fluid that is issued varies widely among individuals. Some do not produce any pre-ejaculate fluid,[7] while others emit as much as 5 ml.[2][6]

Pre-ejaculate contains some chemicals associated with semen, such as acid phosphatase. Some semen markers, such as gamma-glutamyltransferase, are completely absent from pre-ejaculate fluid.[8]

Function

Acidic environments are hostile to sperm. Pre-ejaculate neutralizes residual acidity in the urethra caused by urine, creating a more favorable environment for the passage of sperm. The vagina is normally acidic, so the deposit of pre-ejaculate before the emission of semen may change the vaginal environment to promote sperm survival.[6]

Pre-ejaculate also acts as a lubricant during sexual activity,[6] and plays a role in semen coagulation.[9]

Risks

Studies have demonstrated the presence of HIV in most pre-ejaculate samples from infected men.[1][10][11] Infection with HIV can lead to acquired immunodeficiency syndrome (AIDS).

Popular belief – dating back to a 1966 Masters & Johnson study[12] – states that pre-ejaculate may contain sperm that can cause pregnancy, which is a common basis of argument against the use of coitus interruptus (withdrawal) as a contraceptive method. However, some studies have found that withdrawal could be almost as effective as condoms in preventing pregnancy.[13] There have been several small-scale studies (sample sizes ranging from 4 to 23) that conclude no sperm is present, and thus, pre-ejaculate is ineffectual at causing pregnancy.[1][2][3] Two recent studies have found viable sperm in pre-ejaculate, although the results may not be generalizable due to the small sample sizes.[4][5]

A noted limitation to these previous studies' findings is that pre-ejaculate samples were analyzed after the critical two-minute point. That is, looking for motile sperm in small amounts of pre-ejaculate via microscope after two minutes – when the sample has most likely dried – makes examination and evaluation "extremely difficult."[4] Thus, in March 2011 a team of researchers assembled 27 male volunteers and analyzed their pre-ejaculate samples within two minutes after producing them. The researchers found that 11 of the 27 men (41%) produced pre-ejaculatory samples that contained sperm, and 10 of these samples (37%) contained a "fair amount" of motile sperm (i.e. as few as 1 million to as many as 35 million).[4] As a point of reference, a study showed that, of couples who conceived within a year of trying, only 2.5% included a male partner with a total sperm count (per ejaculate) of 23 million sperm or less.[14] However, across a wide range of observed values, total sperm count (as with other identified semen and sperm characteristics) has weak power to predict which couples are at risk of pregnancy.[15]

It is widely believed that urinating after an ejaculation will flush the urethra of remaining sperm.[16] Therefore, some of the subjects in the March 2011 study who produced sperm in their pre-ejaculate did urinate (sometimes more than once) before producing their sample.[4] However, two things need to be kept in mind. First, the study suggests that some men can leak sperm into their pre-ejaculate (though the authors do not extrapolate on this supposition and the possible causes of such a phenomenon). Second, the authors admit that some of their subjects who submitted sperm-positive pre-ejaculate samples could have actually used their ejaculate – due to failure of producing pre-ejaculate – to avoid the "embarrassment" of not producing pre-ejaculate.[4]

Overproduction

In rare cases, a man may produce an excessive amount of pre-ejaculate fluid that can be a cause of embarrassment or irritation. A few case reports have indicated satisfactory results when such men are treated with a 5-alpha-reductase inhibitor.[17] In one case, a doctor recommended considering the differential diagnosis of prostatorrhea, the emission of prostatic secretions during straining associated with urination or defecation.[17]

See also

Media related to Pre-ejaculate at Wikimedia Commons

References

  1. 1 2 3 "Researchers find no sperm in pre-ejaculate fluid". Contraceptive Technology Update. 14 (10): 154–156. October 1993. PMID 12286905.
  2. 1 2 3 Zukerman Z.; Weiss D.B.; Orvieto R. (April 2003). "Short Communication: Does Preejaculatory Penile Secretion Originating from Cowper's Gland Contain Sperm?" (PDF). Journal of Assisted Reproduction and Genetics. 20 (4): 157–159. PMID 12762415. doi:10.1023/A:1022933320700.
  3. 1 2 Free M, Alexander N (1976). "Male contraception without prescription. A reevaluation of the condom and coitus interruptus". Public Health Rep. 91 (5): 437–45. PMC 1440560 Freely accessible. PMID 824668.
  4. 1 2 3 4 5 6 Killick SR, Leary C, Trussell J, Guthrie KA (2011). "Sperm content of pre-ejaculatory fluid". Human Fertility. 14 (1): 48–52. PMC 3564677 Freely accessible. PMID 21155689. doi:10.3109/14647273.2010.520798.
  5. 1 2 Kovavisarach, E.; Lorthanawanich, S.; Muangsamran, P. (2016). "Presence of Sperm in Pre-Ejaculatory Fluid of Healthy Males". J Med Assoc Thai. 99 Suppl 2: S38–41. ISSN 0125-2208. PMID 27266214.
  6. 1 2 3 4 Chudnovsky, A.; Niederberger, C.S. (2007). "Copious Pre-Ejaculation: Small Glands--Major Headaches". Journal of Andrology. 28 (3): 374–5. PMID 17251594. doi:10.2164/jandrol.107.002576., which cites:
    Chughtai B, Sawas A, O'Malley RL, Naik RR, Ali Khan S, Pentyala S (April 2005). "A neglected gland: a review of Cowper's gland". Int. J. Androl. 28 (2): 74–7. PMID 15811067. doi:10.1111/j.1365-2605.2005.00499.x.
  7. ↑ Vazquez E (1997). "Is it safe to suck?". Posit Aware. 8 (4): 15. PMID 11364482.
  8. ↑ Gohara WF (February 1980). "Rate of decrease of glutamyltransferase and acid phosphatase activities in the human vagina after coitus". Clin. Chem. 26 (2): 254–7. PMID 6101549.
  9. ↑ Chudnovsky, A.; Niederberger, C.S. (2007). "Copious Pre-Ejaculation: Small Glands--Major Headaches". Journal of Andrology. 28 (3): 374–5. PMID 17251594. doi:10.2164/jandrol.107.002576., which cites:
    Beil, R.E.; Hart, R.G. (1973). "Cowper's gland secretion in rat semen coagulation. II. Identification of the potentiating factor secreted by the coagulating glands". Biol Reprod. 8 (5): 613–7. PMID 4713168.
  10. ↑ Pudney, J., Oneta, M., Mayer, K., Seage, G., Anderson, D. (1992). "Pre-ejaculatory fluid as potential vector for sexual transmission of HIV-1". Lancet. 340 (8833): 1470. PMID 1360584. doi:10.1016/0140-6736(92)92659-4.
  11. ↑ Ilaria, G., Jacobs, J.L., Polsky, B.; et al. (1992). "Detection of HIV-1 DNA sequences in pre-ejaculatory fluid". Lancet. 340 (8833): 1469. PMID 1360583. doi:10.1016/0140-6736(92)92658-3.
  12. ↑ Masters, W.H. (1966). Johnson, V.E. Boston, MA: Little, Brown and Company. p. 211.
  13. ↑ Jones, R.K., Fennell, J., Higgins, J.A. and Blanchard, K. (2009). "Better than nothing or savvy risk-reduction practice? The importance of withdrawal" (PDF). Contraception. 79 (6): 407–410. PMID 19442773. doi:10.1016/j.contraception.2008.12.008.
  14. ↑ Cooper, T.G.; Noonan, E., von Eckaedstein, S., Auger, J., Baker, H.W.G., Behre, H.M.; et al. (2010). "World Health Organisation reference values for human semen characteristics". Human Reproduction Update. 16 (3): 231–245. PMID 19934213. doi:10.1093/humupd/dmp048.
  15. ↑ Slama, R.; Eustache, F.; et al. (2002). "Time to pregnancy and semen parameters: a cross-sectional study among fertile couples from four European cities". Human Reproduction. 17 (2): 513. PMID 11821304. doi:10.1093/humrep/17.2.503.
  16. ↑ "Withdrawal Method". Planned Parenthood. March 2004. Retrieved 2006-09-01.
  17. 1 2 Chudnovsky, A. and C.S. Niederberger (2007)
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