The IUI Procedure

The IUI procedure: 1 of 5 things you should know about an IUI


 A Complete Guide to Understanding IUI (intrauterine insemination) and artificial insemination

(Dr Eric Daiter, Board Certified in Reproductive Endocrinology and Infertility)


  • The IUI (artificial insemination) procedure
  • Who should consider an IUI (artificial insemination)?
  • IUI (artificial insemination) success rates
  • IUI (artificial insemination) cost
  • What to consider if IUI (artificial insemination) is unsuccessful


The IUI (artificial insemination) procedure:


Artificial insemination (AI) is a procedure in which sperm is placed directly into a woman’s reproductive tract using means other than sexual intercourse in an attempt to aid in fertility.  The sperm source for artificial insemination can be the woman’s husband (AIH) or a sperm donor (AID).  The sperm can be placed into the vaginal tract (lowest effectiveness), the cervix of the uterus (intra-cervical insemination, improved success compared to vaginal insemination) or the uterine cavity (intrauterine insemination, yielding the highest success rates for AI) using an instrument such as a thin catheter.


IUI, or intrauterine insemination, is a common fertility procedure that is most often performed in an infertility office’s examination room.  The IUI procedure generally has low risk, does not hurt, and can dramatically improve a couple’s chances for conception.  The patient having the IUI procedure often describes the procedure as “like a pap smear.”


  • The IUI procedure must be performed around the time of a woman’s ovulation (release of a mature egg from the ovary) in order to result in a pregnancy.
  • The IUI procedure requires living motile sperm in order to achieve a pregnancy.
  • The sperm sample must be washed prior to IUI.
  • A thin sterile flexible catheter can be used to place the washed sperm sample within the uterine cavity during IUI.
  • There are some rare risks associated with IUI.



(Drawing of an IUI above showing the insertion of washed sperm into the uterine cavity)


1: The IUI procedure must be performed around the time of a woman’s ovulation (release of a mature egg from the ovary) in order to result in a pregnancy. 


Most sperm are thought to live for several days within the uterine cavity and fallopian tubes, so the IUI procedure can be performed up to a few days prior to ovulation for best results.  The mature egg that is released at ovulation is thought to be capable of fertilization for 1 or possibly 2 days after it is released, so the IUI procedure can also be performed within a day or so after ovulation with good success.


Determining the time of ovulation is sometimes tricky.  The menstrual cycle history can suggest when ovulation most likely will occur since ovulation most often takes place 12-14 days prior to the onset of the next menstrual flow.  If a woman has highly regular menstrual cycle intervals every 28 days then she would generally ovulate between cycle days 14 and 16, where cycle day 1 is the onset of heavy bleeding.  Further precision can be obtained with some additional testing.




(Menstrual calendar above with days of menstrual flow in green and probable ovulation days in pink, 12-14 days prior to the onset of the next menstrual flow)


Ovulation predictor kits most often check a woman’s urine using color sensitive tests for Luteinizing Hormone (LH) and the color changes (usually darkens) when there are higher concentrations of LH.  During the menstrual cycle, ovulation is normally triggered hormonally by the LH surge, which is a rapid increase in LH concentration that starts to rise about 36 hours (1½ days) prior to ovulation.  Therefore, we suggest timing IUIs on the day that the ovulation predictor kit turns positive (suggests the LH surge) or within the next two days.




(Ovulation predictor kit above with a reference line, R, and the patient test line, T, in the test window.  When the patient test line darkens significantly the test result is positive)


Serial ultrasound examinations can add even more precision since they follow the maturation of eggs by monitoring the development of ovarian follicles (ovarian cysts that contain an egg).  Normally, at the onset of a menstrual cycle there are several small follicles (each containing an immature egg) that begin to grow and mature.  Ultrasound exams can follow their development and when the follicle is 16mm or greater in diameter it generally contains a mature egg that can be triggered to ovulate.  A woman will eventually trigger her own ovulation naturally with the LH surge but infertility specialists can also trigger ovulation with the injection of a medication (usually human chorionic gonadotropin or hCG) to more predictably (and accurately) time procedures such as IUI or IVF.




(Ultrasound above with a small ovarian follicle measuring 8mm diameter, which contains an immature egg, at the beginning of a menstrual cycle)




(Ultrasound above with a mid-size ovarian follicle measuring 14 x 15mm in diameter, which contains a mature egg about 80% of the time)




(Ultrasound above with a large ovarian follicle measuring 19 x 20mm in diameter, which contains a mature egg about 99% of the time)


Blood work for estradiol, LH and progesterone concentrations 1-2 times a week can provide additional information.  Blood work is most useful to confirm the accuracy of other ovulation tests.  Blood work is rarely used by itself to time artificial insemination or IUI since it is easy to miss the LH surge when blood work is done only once or twice a week.  Blood work is sometimes useful when a woman’s menstrual cycle intervals are highly irregular (for example every 1-2 months) in order to detect when a follicle is growing more actively (the estradiol will begin to rise sharply) and then ultrasound examinations can be used to precisely time when the follicle is mature and medication can be given to trigger ovulation.


2: The IUI procedure requires living motile sperm in order to achieve a pregnancy.


A common guideline is that at least one million motile sperm are required, and at least 5-10 million motile sperm are ideal, for good success rates with IUI.  However, from personal experience, I can recall several patients with total motile sperm counts of much less than one million at IUI who successfully achieved a pregnancy.  Only one sperm actually fertilizes the mature egg, but in order to increase the chances of delivering motile sperm to the mature egg within the fallopian tube many sperm are placed within the woman’s reproductive tract.  My impression is that the success rates with IUI using very low motile sperm counts are indeed significantly lower than the success rates with IUI using higher motile sperm counts, which is consistent with these common guidelines.  But, in the event that the husband has a very low motile sperm count and the couple feels strongly that they would prefer a child with the husband’s sperm rather than donor sperm, I will offer IUI as an entry level treatment option as long as the couple understands that the success rates are significantly decreased.  If these IUIs are successful, then that is great.  If these IUIs are unsuccessful after a few cycles, then different, more expensive, and more complex procedures are always available for consideration.


The method of collection (and delivery to the lab) for the sperm sample is important in order to increase the yield of motile sperm.  The sample is ideally collected by manual masturbation into a clean, warm, plastic container (with a wide opening to limit the loss of sample material during collection) that is properly labeled (first and last name ideally along with a second personal identifier such as date of birth or social security number).  The lid should be properly secured and if the specimen is collected anywhere other than within the infertility office then the container should be insulated to prevent heat loss.  Sperm is highly sensitive to small temperature changes and if the sample gets either cold or hot the motility of the sperm can be severely compromised.  I suggest wrapping the entire specimen container with aluminum foil two times (twice) to limit heat loss, placing the foil wrapped container in a sock to further insulate it, and delivering this insulated container to the office for processing as soon as possible.  When wrapped in this way, the specimens delivered to my lab have been of very high quality even when collected several hours prior to arrival at the lab.  Maintaining the proper temperature by limiting heat loss seems to be very important.




(A clean specimen cup properly labeled with the patient’s name and date of birth is wrapped with two layers of aluminum foil, for insulation during transportation to the laboratory)


Generally, 2-5 days of sexual abstinence is suggested in order to obtain the best quality sperm but this is not an absolute rule.  For example, when IUIs are performed on consecutive days the sperm sample collected for the second day of IUI is quite often of better quality than the sperm sample from the first day.  Additionally, the available literature suggests that more than one hundred million sperm can be produced per day.  Therefore, when available, I prefer sperm samples that are collected after a few days of abstinence but I also do not hesitate to use good quality samples that are collected after shorter periods of abstinence.


3: The sperm must be washed prior to IUI.

Sperm must always be washed free of semen prior to IUI since the semen contains prostaglandins.  Prostaglandins are molecules that would cause extremely painful uterine contractions for several minutes to a few hours if placed directly into the uterine cavity.  Semen also contains oxygen reactive species of molecules that might limit the ability of the sperm to fertilize the egg.


Sperm is normally released within a gelatinous fluid called semen, this semen quickly becomes less viscous (thick), and within 15-30 minutes this fluid usually becomes a thin liquid.  Once the semen has thinned out (that is, liquefaction has occurred) the sperm can be separated from the semen using a variety of washing procedures within the laboratory.


Actual video of human sperm is available for viewing if you decide to download the Guide.  Some viewers may find the videos overly graphic while most viewers find them informative and interesting.

(Unwashed sperm sample from patient “A” that shows the sperm having some difficulty moving through viscous gelatinous semen.  This sample was washed and the results are shown in the next video. Double click on lower left icon to play video)


A relatively simple but highly effective wash procedure involves a few steps: mixing the whole semen sample that was collected with a warm inert buffered medium such as human tubal fluid (fluid collected from fallopian tubes that contains molecules that help to activate sperm to prepare them for fertilizing an egg); centrifuging this mixed sample to pellet the sperm cells at the bottom of the tube; removing and discarding the liquid (semen and medium) from the tube while preserving the sperm pellet at the bottom of the tube; re-suspending the sperm pellet in additional warm inert buffered medium; centrifuging the sample once again to pellet the sperm; removing and discarding the liquid (remaining semen and buffered medium) while preserving the sperm pellet at the bottom of the centrifuge tube; and re-suspending this sperm pellet in additional inert buffered media.


Actual video of human sperm is available for viewing if you decide to download the Guide.  Some viewers may find the videos overly graphic while most viewers find them informative and interesting. 

(The washed sperm sample from patient “A “ that shows the improvement in forward progression and movement of the sperm compared to the unwashed specimen in the prior video.  Double click on lower left icon to play video)


The sperm sample should be analyzed for volume, sperm concentration, sperm motility, and sperm morphology (shape) prior to and following the washing procedure to determine initial quality and yield after wash.  Ideally, at least five million motile sperm will be available after the wash procedure for the IUI.


4: A thin sterile flexible catheter can be used to place the washed sperm sample within the uterine cavity during IUI.


Normally a thin flexible plastic catheter can be used to deliver the sperm into the uterine cavity without causing any significant discomfort to the patient.  A speculum is used to identify the cervical opening to the uterus, a catheter is attached to a syringe that contains the sperm sample, the catheter is bent slightly to accommodate the angle of the cervical uterine junction, the catheter is inserted into the uterine cavity, and the sperm is slowly injected into the uterus.  After the IUI procedure is completed, the woman is asked to lie comfortably on the exam table for about 5 minutes prior to returning to her usual activities.


5: There are some rare risks associated with IUI.


Whenever an instrument, including a catheter, is placed within the uterine cavity there is a chance of inadvertent damage to the uterine lining or perforation through the uterine wall.  Historically, metal catheters were used for IUI and these risks were more significant.  Nowadays, a flexible and soft catheter is generally used so these risks are minimal.  For example, I have always used the soft sterile catheters and I have never personally had a complication with IUI (in several thousand IUIs).


There is a risk of introducing foreign material into the uterine cavity along with the sperm.  Semen, which contains prostaglandins and other molecules that should not be placed directly into the uterine cavity, can be inadvertently inserted during IUI if the sample was not thoroughly washed.  This could result in painful contractions after IUI or reduced fertility.  Also, some infertility clinics mix chemicals with the inert buffered wash media in an attempt to improve the performance of the sperm, but many of these chemicals are relatively new to this process and they can affect the sperm or the resulting fertilized egg in an unanticipated and negative way.  My practice does not use any of these additives in order to limit potential unforeseen complications.  If the husband or sperm donor has a dangerous viral infection such as HIV or Hepatitis, then the wife may be more likely to get this infection from a washed sperm sample containing very small amounts of virus when it is placed directly into the uterine cavity as compared to the placement of whole semen (with sperm and larger amounts of virus) directly into the vaginal vault during intercourse.  Medical researchers recently identified this risk so my office now strongly suggests that the husband is tested for HIV, Hepatitis B and Hepatitis C prior to an IUI that uses his sperm.  All sperm donors are routinely tested for these viruses before the sperm is released for IUI.


If you like what you have been reading then download your entire free copy of “The Complete Guide to Understanding IUI,” including actual videos of human sperm samples (showing improvement in the movement of the same sperm before and after the wash and a video of sperm moving in place, taken by Dr. Daiter (warning: some consider these photos graphic or gross).



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