WHAT HAS CHANGED / IMPROVED IN THE TREATMENT AND PRACTICE OF IVF

Laboratory technical conditions,  culture mediums  in which embryos are stored in

Freezing and Thawing  techniques. The success rate of frozen embryo transfer is comparable to that of fresh embryo transfer. Some clinics began to prefer frozen embryo transfer already.

We know that multiple pregnancies increase the risk of preterm birth and consequently  neurological problems in newborn. The rate of twin pregnancies in natural pregnancies is  1 out of 90 pregnancies while it increases up to  20-30% in IVF pregnancies. The most important reason is the transfer of more than one embryo. Considering the complications of the mother and babies related to  multiple pregnancy over the years, restrictions have been imposed on the number of embryos to be transferred. According to the regulations in Turkey, one embryo per transfer in the first two trials under the age of 37, two embryos over the age of 37 . These limitations resulted in a decrease in multiple pregnancy rates.Successful outcomes with the use of Short Protocol (Antagonist cycles) and frozen embryo transfer, especially in patients with Polycystic Ovarian Syndrome, have changed the treatment approach. In the stimulation process of these patients, when there were overgrowth of the ovaries (hyperstimulation), the treatment had been either cancelled or gonadotropin injections stopped for a while to prevent serious complications. Today, we have some tools to overcome hyperstimulation with comparable good clinical outcomes
     - Short (Antagonist) Protocol
     - Triggering ovulation with GnRH-Agonist instead of hCG
     - Freezing all embryos

Genetic Diagnosis and Its Applications in IVF : PGS (Prenatal Genetic Screening)PGD ( Prenatal Genetic Diagnosis)
The rate of chromosomal abnormalities in eggs and embryos obtained  IVF treatment is higher than normal pregnancies and increases with maternal age. This has been known for many years. The development of  abnormal  embryos is often slower than normal ones  and most of the abnormal embryos may present some clues when examined under the microscope. However, embryos growing in normal fashion and look morphologically normal under the microscope may also have chromosomal abnormalities. It is possible to obtain cells from the embryo and examine gor chromosomal disorders at certain periods of embryo development. 
PGD ​​(Preimplantation Genetic Diagnosis) is performed for the diagnosis of a previously known or diagnosed chromosomal disorder or genetic disease.  The same application for screening purposes is called PGS (Prenatal Genetic Screening). The process of taking embryonic cells from the embryo is called Embryo Biopsy. Previously, this process is mostly done from the third day embryos, but today it is mostly obtained from the 5th day embryo called Blastocyst. While the number of chromosomes that can be investigated was at most five (13, 18, 21, X, Y), now all 46 chromosomes can be searced for. As a result of all these investigations, the success rate has been increased with the transfer of embryos with normal karyotype.

Embryo Pooling: The number and quality of oocytes decrease with age. Quality reduction shows itself with less fertilisation, less embryos and less ongoing pregnancy rates. Although many hormonal and non-hormonal treatments have been tried in recent years, there has been no proven treatment option in patients with low ovarian reserve. For this purpose, various experimental studies have been done  including  stem cells but none has been implemented for clinical use at the moment. 

The only fact is ; the higher the number of embryos with normal morphology that can be obtained with each trial, the more the pregnancy rate. This possibility is further increased by PGS. Embryos  are obtained with multiple stimulations without delay, and these embryos are frozen after the verification of normal karyotype by PGS on Day 5. Healthy ones are pooled and transferred in the following time period. This method is called Embryo Pooling. 

Dual Stimulation: The applications in IVF treatment are based on the physiology of the normal monthly cycle. After the menstrual period, the egg develops, about 14 days of pregnancy after ovulation. The aim of treatment is to develop a large number of eggs under control with the drugs used in this period. Even if we freeze the embryos after the egg collection, no additional stimulation is made that month, the drugs stop. Patients who have been diagnosed with cancer over the years, but who want to have children, chemotherapy or radiotherapy in patients who will have toxic effects on the ovary before these treatments can be stimulated by stimulating the ovaries to obtain eggs and applications. In these stimulations, independent of the menstrual cycle, healthy eggs and embryos were obtained. These experiences show that, after ovulation, there can be follicle development in the egg immediately. After the time of normal egg collection, especially in patients with poor ovarian reserve, the ovaries are stimulated with a second hormonal wave and eggs of similar number and quality can be obtained. This positively affects the pregnancy rates.

Endometrial Thickness: It is essential to see suitable endometrial pattern and thickness for better outcomes after embryo transfer. The space occupying lesionsa and adhesion, if any, must be treated in advance. In some women, endometrial thickness cannot reach the desired level due to inherent structural variations or previous operations. Although there are pregnancies with thinner  endometrial tissue, pregnancy rates are higher in with endometrial thickness of 7-8 mm and above. In the treatment of thin endometrium, there is no definitive method, including high-dose hormone therapy. It is one of the topics in IVF field that no definitive treatment has been shown syccessful yet.