What procedures are required for in vitro fertilization?

Patient's question:

Low sperm count 2007

Doctor's answer:

Controlled Ovulation Induction: Due to the variability in the length of natural menstrual cycles among individuals and even within the same patient across different cycles, it is difficult to schedule oocyte retrieval. Moreover, in a natural cycle, only one dominant follicle develops, leading to the formation of only one embryo after fertilization, with a low pregnancy rate upon transferring a single embryo. Therefore, controlled ovarian hyperstimulation is required to enhance and improve ovarian function, allowing for the retrieval of multiple healthy oocytes unrestricted by natural cycles. This facilitates the transfer of multiple embryos and ensures synchronization between luteal development and endometrial function. Controlled ovarian hyperstimulation typically involves first using a GnRH agonist to suppress endogenous FSH and LH, followed by administration of HMG or FSH for ovulation induction to stimulate follicular growth in the ovaries. The dosage of medication is adjusted based on the patient's response to the treatment. The number of oocytes retrieved varies depending on the patient's age and the dosage of medication used.
Follicle Monitoring: To evaluate the effectiveness of ovarian stimulation and determine the timing of oocyte retrieval, transvaginal ultrasound is used to monitor follicle size, accompanied by blood tests to measure estradiol (E2) levels, allowing for medication dosage adjustments. When two or more follicles are greater than 1.8 cm in diameter, and the number of follicles greater than 1.4 cm is proportional to the E2 level, human chorionic gonadotropin (hCG) is administered to promote follicular maturation. Oocyte retrieval is performed 34–36 hours after hCG injection.
Oocyte Retrieval: The most common method involves local anesthesia, with transvaginal ultrasound guidance to insert an oocyte retrieval needle through the vaginal fornix to reach the ovaries and aspirate the oocytes. The oocytes are immediately transferred to a culture dish containing embryo culture medium and placed in a 37°C incubator for cultivation.
Sperm Retrieval: Sperm retrieval is performed on the same day as oocyte retrieval. Beforehand, the hands are washed, and sperm is collected through masturbation. The provided cup is sterile, and care should be taken not to touch the rim or the inside of the cup during collection. The collected sperm is processed using the swim-up method or Percoll density gradient centrifugation.
In Vitro Fertilization (IVF): Four to five hours after oocyte retrieval, the processed sperm is combined with the oocytes in the same culture dish and co-cultured for 18 hours. Under a microscope, fertilization can be observed. If the sperm quality is poor and natural fertilization is not possible, intracytoplasmic sperm injection (ICSI) must be performed (see Intracytoplasmic Sperm Injection).
Embryo Transfer: Fertilized eggs can develop to the 8–16 cell stage in vitro within 48–72 hours. At this stage, the number of embryos to be transferred is determined based on the patient's age, previous pregnancy history, and embryo quality. Excess embryos can be cryopreserved. Embryo transfer generally does not require anesthesia. Currently, most transfers occur 2–3 days after fertilization, while my clinic typically transfers embryos 3–5 days after fertilization. Delaying embryo transfer increases the requirements for in vitro culture conditions, but it aligns better with physiological pregnancy and allows for natural selection to eliminate poor-quality embryos, thereby improving pregnancy rates and reducing multiple pregnancies.
Hormone Support After Embryo Transfer: Currently, we primarily use intravenous injections of progesterone to support the corpus luteum. If pregnancy is confirmed, hCG is switched to continue supporting the luteum until the 10th week of pregnancy. Fourteen days after embryo transfer, pregnancy can be confirmed through a urine test or blood draw.