Reproductive Surgery plays an important role in the management of infertility. Today, it is done with minimally invasive techniques such as hysteroscopy or laparoscopy. Hysteroscopy is a procedure in which the gynecologist examines the inside of the womb (uterus) using a small telescopic instrument inserted via the vagina and the cervix (the neck of the uterus). It allows the gynecologist to make sure that the womb is normal or contains a fibroid, polyp, scar tissue or any other conditions such as a septum. Hysteroscopic correction of these abnormalities is often followed by spontaneous pregnancy and improved in-vitro fertilization (IVF) outcome.
Laparoscopy is an operation in which the surgeon makes a small incision below or above the navel and inserts an instrument that allows the surgeon to look inside the abdominal cavity and examine the internal organs. It is used to treat a variety of conditions including endometriosis, ovarian cyst, ectopic pregnancy, uterine fibroids, and many others.
In the context of IVF, swollen and blocked tube (hydrosalpinx) reduces the chance to conceive after IVF. The fluid inside the hydrosalpinx leaks into the uterus and impairs the chances to conceive. Laparoscopic removal of hydrosalpinx increases the IVF live birth rate.
Reproductive surgery is also used for preservation of fertility in women who require radiation or chemotherapy for cancers or other conditions. Surgical preservation of fertility consists of moving the ovaries outside the radiation field (ovarian suspension), removal of ovarian tissue for freezing and transplanting the ovarian tissue..
Pre-Implantation Genetic Diagnosis (PGD) is a relatively new procedure. Nevertheless, over 2,000 unaffected children have been born following PGD for various genetic defects in about 30 clinics worldwide.
For couples at risk of having children with an inherited disease, preimplantation genetic diagnosis (PGD) is a new approach to preventing the birth of affected children. Other methods of prenatal diagnosis such as amniocentesis or chorion villus sampling (CVS) involve taking samples from an established pregnancy. If the fetus is diagnosed as affected, couples then have to decide whether or not to terminate the pregnancy. Some couples may have several terminations trying for a healthy child.
With PGD, In Vitro Fertilization (IVF) treatment is used to screen early embryos for the inherited defect causing the disease within a few days of conception. Couples can then choose to have only those embryos diagnosed as free of the disease replaced in the woman’s uterus knowing that any resulting pregnancy should be normal.
Dr. Asangla Ao, formerly of Hammersmith Hospital, London, UK, where the first baby was born after preimplantation diagnosis in 1989, leads the scientific side of the PGD team at the MUHC Reproductive Centre.
Frequently asked questions about PGD
Q. Which inherited diseases can be screened by PGD at the MUHC Reproductive Centre?
A. At present, we offer PGD for X-linked diseases, which only affect boys, for example, Duchenne muscular dystrophy (DMD), haemophilia A , adrenoleukodystrophy, Hunter's disease, by identifying the sex of embryos and transferring only female embryos. We also offer PGD for single gene defects such as cystic fibrosis (CF) - the common deletion (^F508), spinal muscular atrophy (SMA) and Myotonic Dystrophy (DM). We also perform Aneuploidy screening and chromosome translocations to detect abnormalities which may cause spontaneous abortions in early pregnancy. We can do PGD for all single gene defects where the specific mutation is identified and as long as we can develop a special genetic probe for the disease.
Q. Do you need to undergo IVF? Why?
A. Yes. It is generally necessary to have IVF because the PGD procedure requires the testing of embryos at a very early stage of development before implantation in the womb. Initially, therefore, you need to make an appointment at the MUHC Reproductive Centre to assess your suitability for IVF and PGD. This will involve taking a full medical and genetic history from you and your partner and a physical examination for the female partner. In addition, we ask one or both of you for a small blood sample for us to check the diagnostic tests we plan to use to screen your embryos.
For selected patients, IVM (In Vitro Maturation) can be offered for PGD instead of IVF. Your physician will explain why this approach may benefit you.
Q. What does PGD involve?
A. In an average IVF cycle, several eggs may be collected in hopes of having 5 or 6 embryos reach the stage where they can be biopsied. For PGD, one or two cells are removed or "biopsied" from each embryo by micromanipulation when the fertilized eggs have divided into approximately eight cells, which usually occurs early on the morning of the third day following fertilization. This allows the genetic material or DNA in these cells to be analysed for the genetic defect causing the inherited disease.
When the results are ready, patients are asked to come to the hospital for their test results, which are carefully explained. The embryos considered to have the best chance of implantation and establishing pregancy are identified for the patient.
There are too few pregnancies following PGD to be sure there is absolutely no risk of abnormality or minor effects that may only appear later in childhood. For this reason, we ask your permission to allow a pediatrician to examine the babies at birth and to follow up their development during childhood.
Sometimes there may be one or more good quality unaffected embryos remaining after transfer. You may decide that you want these embryos frozen (cryopreserved) for transfer in a later cycle.
Q. How accurate is PGD?
A. Genetic analysis of single cells is technically demanding and prone to errors of various kinds. Also, the early human embryo has a relatively high incidence of genetically abnormal cells which, is used for genetic analysis may on some occasions result in misdiagnosis. For these reasons, it is important for you to be aware that we cannot be 100% accurate with the diagnosis for each embryo. However, reagents are extensively tested beforehand and we do everything we can to minimize technical errors.
A few misdiagnoses have been reported in the literature but each has involved a different genetic test and is not a reliable guide to the likely incidence in your case. Nevertheless, you should consider carefully the possibility of having a conventional prenatal diagnosis by CVS or amniocentesis if a pregnancy is established to confirm that the fetus is not affected.