Many of our patients are undergoing fertility treatment for male factor indications, and undergo insemination therapy. This may be patients who are using donor sperm from a sperm bank, or patients who are using their partner's sperm, but the sperm has been frozen (partner out of town, or other indications). We are often asked if the success rates will be affected by the use of frozen versus fresh sperm. As well, we are asked if the number of inseminations performed per cycle will affect the success rates. There is a body of studies that have been done to address these specific questions, and our clinic's interpretation of the literature is the following.
The first consideration addresses which type of insemination provides the best outcome when using frozen sperm. A number of studies have looked at this question, and when all the data from those studies are compiled and analyzed, results indicate that if an intrauterine insemination (IUI) is performed (sperm placed directly in the uterus), the odds are 2.5 times greater that a pregnancy will occur, than if an intracervical insemination (ICI) is performed (sperm placed at the entrance of the cervix) (5% vs. 14% monthly chance of pregnancy) (1, 2). When sperm are placed at the cervix, many of them are “lost” as they travel through the cervix and into the uterus, to then find their way to the fallopian tubes. This dilutes the actual numbers that make it to the egg in the fallopian tube, and therefore decreases chances of success. Performing 2 intracervical inseminations in one cycle (9% chance of pregnancy) did not bring success rates close to what one intrauterine insemination achieved (15% monthly chance of pregnancy) (2).
Next consideration addresses if fresh sperm is better than frozen sperm. Two studies have addressed this best, and indicate that the critical components that will provide comparable pregnancy rates are the performance of an intrauterine insemination (IUI), accurate timing of the insemination (relative to the ovulation event), and adequate concentration of sperm inseminated (called total motile count=TMC) (3, 4). The most accurate way to time the insemination is by using ovulation predictor kits (OPK), or by administration of an HCG injection to trigger the ovulation event. Ovulation predictor kits have been evaluated and the kit we recommend is the Clear Blue Easy ovulation kit. First detection of an LH surge is most likely to occur in the morning, and our recommendation is to do one test/day, in the morning (5). The best timing for an intrauterine insemination using frozen sperm is within 24-48 hours after a positive LH surge as detected by an Ovulation Predictor kit. In a well-designed study, using first positive OPK results to time insemination, 5% of total pregnancies resulted in cycles where the IUI was done within 24 hours of the positive OPK result, 90% of total pregnancies if within 24-48 hours, and 5% of total pregnancies if past 48 hours (5). Quite a few studies have evaluated the minimum number of inseminated sperm required to achieve an adequate pregnancy rate. Most indicate a total motile count between 6-15 million. This means that after thawing the frozen sperm specimen, the lab must recover between 6-10 million moving sperm. Most sperm banks provide a post thaw guarantee of 10-15 million/vial if prepped for an IUI (sperm already washed), or 15-20 million/vial if prepped for an ICI (unwashed sperm).
Next consideration addresses sperm washing techniques. There are a number of different laboratory techniques for washing and preparing sperm for insemination. As it turns out, there is no difference in pregnancy rates based on the sperm preparation technique. This holds for both the freezing technique and the post thaw washing technique (if ICI prepped) (6). This also applies if the sperm is pre-washed by the laboratory prior to freezing (if IUI prepped) (7). As long as an adequate TMC is reached post freeze-thaw, pregnancy rates hold steady.
The last consideration is: would one IUI per cycle reach adequate pregnancy rates, or would 2 IUI's be better? Many studies have been done evaluating this question, and while individual studies may show different results, the majority of studies indicate that one IUI/cycle is adequate, and 2 IUI's does not improve pregnancy rates, as long as the IUI is well timed, and the TMC inseminated is adequate (2, 8, 9, 10, 11).
In conclusion: We take guidance from the best published literature, and use the following guidelines for managing frozen sperm intrauterine insemination cycles at Pacific Fertility Center:
- Determine best timing of intrauterine insemination or IUI:
First positive ovulation predictor kit (OPK) if OPKs are reliable, or HCG injection as administered according to our instructions.
- Do one IUI 24-48 hours after first positive OPK, or 24-48 hours after administration of HCG
- Do intrauterine insemination (not intracervical insemination or ICI)
- Assure insemination with adequate total motile count or TMC
We will thaw sperm until we have a TMC of 10 million
If attention is paid to these management points during your treatment cycle, you should feel reassured that your chances of achieving a pregnancy is comparable to those if you were using fresh sperm.
-- Isabelle Ryan, M.D.
- 1. Goldberg et al, Fertil Steril. 1999 Nov; 72(5):792-5
- 2. Carroll et al, Fertil Steril. 2001 Apr:75(4):656-60
- 3. Subak et al, Am J Obstet Gynecol. 1992 Jun; 166:1597-604
- 4. Bordson et al, Fertil Steril. 1986 Sept;46(3):466-9
- 5. Khattab et al, Hum Reprod. 2005 Sep;20(9):2542-5
- 6. Byrd et al, Fertil Steril. 1994 Oct;62(4):850-6
- 7. Wolf et al, Fertil Steril. 2001 July;76(1):181-5
- 8. Centola et al, Fertil Steril. 1990 Dec;54(6):1089-92
- 9. Lincoln et al, J Assist Reprod Genet. 1995 Feb;12(2):67-9
- 10. Khalifa et al, Hum Reprod. 1995 Jan;10(1):153-4
- 11. Matilsky et al, J Androl. 1998 Sept-Oct;19(5):603-7