Semen Processing for Insemination

Semen Processing

During coitus, the ejaculate is deposited around the cervix. Only progressively motile sperm having a normal morphology can penetrate and migrate through the cervical mucus. 

In addition, there are factors in seminal plasma that actually inhibit fertilization (de capacitation factors), and prostaglandin. Although fertile sperm with progressive motility and normal morphology are able to pass through into the uterus, they can’t fertilize an egg until its seminal plasma coating are removed. 

The sperm processing performed in the laboratory removes these harmful substances, along with dead or damaged sperm. The processing also concentrates all viable sperm into an amount ideally suited for Intra Uterine Insemination (IUI), a process by which a physician clinically places sperm within the uterus directly through the cervix.

Semen deposited inside the vaginaSperm deposited inside the uterus
Cervical mucus is a barrierCervical mucus barrier bypassed
Cervical mucus prevents entry of seminal plasmaSperm washing removes seminal plasma
Prevents abnormal sperm, non-motile sperm and other cellular forms from entrySperm processing removes non-motile sperm and most of the abnormal sperm
Only few sperm in an ejaculate are able to enter cervical mucusAlmost all of the viable sperm in an ejaculate are deposited inside the uterus

Optimum time of IUI depends on any one or all of the following: Hormone levels, ultrasound measurement of your spouse’s follicles, urinary ovulation prediction kit response, and the sperm quality. 


  • Semen Collection and Processing Methods by R.S. Jeyendran
    Cambridge University Press, Cambridge, UK. 

Factors to improve IUI outcome

Intrauterine insemination (IUI) efficacy depends on the timing of insemination and the number of inseminations.

To achieve high pregnancy success double inseminations is recommended:

  • First insemination performed 12 to 18 hours post-hCG injection or the same day as a positive urine test 
  • Second insemination 24 hours following the first insemination.
Number of PatientsPregnancy*
Standard IUI protocol: Single insemination 36 hours or later post hCG: “After Ovulation53516.8%
Double inseminations  protocol: First insemination performed 12 to 18 hours post hCG injection and the second insemination 24 hours following the first: “Before and after Ovulation46931.6%

Based on the results in the table, first insemination performed before and second insemination after ovulation yielded the highest pregnancy outcomes. 

Also, reports on data analysis reveal that the fertile window for IUI is just prior to ovulation**

Please Note: In domesticated animals maximum fertility is achieved if insemination is performed before ovulation.

Insemination therefore must occur before ovulation: it appears that the standard IUI protocol of insemination 30 to 36 hours post hCG may be missing the mark.

Should a single-insemination procedure prove more practical, then the insemination should be performed at the earlier recommended time for both ovulation detection methods.


  • Deary et al., Single versus double insemination: a retrospective audit of pregnancy rates with two treatment protocols in donor insemination. Hum Reprod 1997; 12: 1494-6.
  • Silverberg et al., A prospective, randomized trial comparing two different intrauterine insemination regimens in controlled ovarian hyperstimulation cycles. Fertil Steril 1992; 57:357-61.
  • Ragni et al., Efficacy of double intrauterine insemination in controlled ovarian hyperstimulation cycles. Fertil Steril 1999;72: 619-22.
  • Khalifa et al., The value of single versus repeated insemination in intra-uterine donor insemination cycles. Hum Reprod 1995; 10: 153-4.
  • Ransom et al., Does increasing frequency of intrauterine insemination improve pregnancy rates significantly during superovulation cycles? Fertil Steril 1994; 61: 303-7.


  • Dunson et al., Assessing human fertility using several markers of ovulation. Statist Med 2001; 20:965-78.
  • Wilcox et al., Timing of sexual intercourse in relation toovulation.Effects on the probability of conception, survival of the pregnancy, andsex of the baby. N Engl JMed 1995; 333:1517-21.
  • Wilcox et al., The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study. BMJ2000; 321:1259-62.

Availability of Sperm on Demand

The success of IUI depends heavily on the immediate availability of quality sperm. In the event that you are not able to provide an ejaculate at the appropriate time, the ejaculate could be incubated overnight in special refrigeration media.

If however ejaculate needs to be available at a later date, then the ejaculate could be cryopreserved and used at the time of ovulation.


  • Semen Collection and Processing Methods by R.S. Jeyendran
    Cambridge University Press, Cambridge, UK.