In vitro fertilisation (IVF) is a process by which an egg is fertilised by sperm outside the body: in vitro. IVF is a major treatment for infertility when other methods of assisted reproductive technology have failed.
When a woman’s natural cycle is monitored to collect a naturally selected ovum (egg) for fertilisation, it is known as natural cycle IVF. The fertilised egg (zygote) is then transferred to the patient’s uterus with the intention of establishing a successful pregnancy.
IVF may be used to overcome female infertility in the woman due to
- (1) problems of the fallopian tube,
- (2) endometriosis and
- (3) unexplained factors making fertilisation in vivo difficult.
It may also assist in male infertility, where there is a defect in sperm quality, and in such cases intracytoplasmic sperm injection (ICSI) may be used, where a sperm cell is injected directly into the egg cell. This is used when sperm have difficulty penetrating the egg, and in these cases the partner’s or a donor’s sperm may be used.
ICSI is also used when sperm numbers are very low. ICSI results in success rates a bit high to those of IVF.
For IVF to be successful it typically requires healthy ova, sperm that can fertilise, and a uterus that can maintain a pregnancy. Due to the costs of the procedure, IVF is generally attempted only after less expensive options have failed.
Theoretically, in vitro fertilisation could be performed by collecting the contents from a woman’s fallopian tubes or uterus after natural ovulation, mixing it with semen, and reinserting into the uterus. However, without additional techniques, the chances of pregnancy would be extremely small.
Such additional techniques that are routinely used in IVF include ovarian hyperstimulation to retrieve multiple eggs, ultrasound-guided transvaginal oocyte retrieval directly from the ovaries, egg and sperm preparation, as well as culture and selection of resultant embryos before embryo transfer back into the uterus.
In most patients, injectable gonadotropins (usually FSH analogues) are used under close monitoring. Such monitoring frequently checks the estradiol level and, by means of gynecologic ultrasonography, follicular growth. Typically approximately 10 days of injections will be necessary.
Final Maturation and Egg Retrieval:
The eggs are retrieved from the patient using a transvaginal technique called transvaginal oocyte retrieval, involving an ultrasound-guided needle piercing the vaginal wall to reach the ovaries. Through this needle follicles can be aspirated, and the follicular fluid is handed to the IVF laboratory to identify ova.
Egg and Sperm Preparation:
In the laboratory, the identified eggs are stripped of surrounding cells and prepared for fertilisation. An oocyte selection may be performed prior to fertilisation to select eggs with optimal chances of successful pregnancy.
The sperm and the egg are incubated together at a ratio of about 75,000:1 in the culture media for about 18 hours. In most cases, the egg will be fertilised by that time and the fertilised egg will show two pronuclei. In certain situations, such as low sperm count or motility, a single sperm may be injected directly into the egg using intracytoplasmic sperm injection (ICSI).
The fertilised egg is passed to a special growth medium and left for about 48 hours until the egg consists of six to eight cells.
Typically, embryos are cultured until having reached the 6–8 cell stage three days after retrieval.
Embryo Transfer :
Embryos are failed by the embryologist based on the amount of cells, evenness of growth and degree of fragmentation. The number to be transferred depends on the number available, the age of the woman and other health and diagnostic factors.
The embryos judged to be the “best” are transferred to the patient’s uterus through a thin, plastic catheter, which goes through her vagina and cervix. Several embryos may be passed into the uterus to improve chances of implantation and pregnancy.
Success Rates :
IVF success rates are the percentage of all IVF procedures which result in a favorable outcome. Due to advancement in reproductive technology, the IVF success rates are substantially better today than they were just a few years ago.
The most current data available in the United States a 2009 summary complied by the Society for Reproductive Medicine which reports the average national IVF success rates per age group using non-donor eggs (see table below).
|Live Birth Rate||41.4||31.7||22.3||12.6|
Live Birth Rate :
The live birth rate is the percentage of all IVF cycles that lead to a live birth.
In 2006, Canadian clinics reported a live birth rate of 27%. Birth rates in younger patients were slightly higher, with a success rate of 35.3% for those 21 and younger, the youngest group evaluated. Success rates for older patients were also lower and decrease with age, with 37-year-olds at 27.4% .
Success or Failure Factors:
The main potential factors that influence pregnancy (and live birth) rates in IVF have been suggested to be maternal age, duration of infertility or subfertility, bFSH and number of oocytes, all reflecting ovarian function. Optimal woman’s age is 23–39 years at time of treatment.
Other determinants of outcome of IVF include:
- A body mass index (BMI) over 27 causes a 33% decrease in likelihood to have a live birth after the first cycle of IVF, compared to those with a BMI between 20 and 27. Also, pregnant women who are obese have higher rates of miscarriage, gestational diabetes, hypertension, thromboembolism and problems during delivery, as well as leading to an increased risk of fetal congenital abnormality. Ideal body mass index is 19–30.
- Success with previous pregnancy and/or live birth increases chances
- Low alcohol/caffeine intake increases success rate
- The number of embryos transferred in the treatment cycle.
- Other factors of semen quality.
Complications in the IVF procedure:
Possible risks may occur throughout the procedure and depend on the specific step of the procedure. During ovarian stimulation, hyperstimulation syndrome may occur. In moderate cases, may have symptoms of heartburn, gas, nausea, or loss of appetite. In severe cases, patients who have sudden excess abdominal pain, nausea, vomiting and will result in hospitalisation.
Ectopic pregnancy may also occur if a fertilised egg develops outside the uterus, usually in the fallopian tubes and requires immediate destruction of the foetus.
There might be Pelvic infection.
Couples also pass through physical as well as psychological strain.