Essentially, it involves causing localized damage to the ovarian stroma (which is the outer part of the ovary). In the process of recovering from the damage, the receptors in the ovary become more sensitive to FSH, and hence, ovulation is more likely to occur.
The exact mechanism of the increase in ovarian sensitivity to FSH is not known, but is thought to involve changing levels of hormones such as Inhibin, and other “intra” ovarian molecules called Insulin-like growth factors (IGF).
The idea of ovarian damage leading to subsequent ovulation in PCOS women arose from the olden days, where women with PCOS were diagnosed by taking a piece of tissue out of the ovary. The operation involved opening the woman’s abdomen, and was called “wedge resection”.
The Gynaecologists of the day noted that a lot of these women subsequently ovulated and conceived, and so “wedge resection” became a treatment for lack of ovulation. Yes, times have certainly changed!
In the late ‘80s when I started training in Obstetrics & Gynaecology, a French Laparoscopic Surgery Unit showed that similar results in improving ovulation rates could be achieved by performing Laparoscopic Ovarian Drilling (LOD). The Laparoscopic procedure involves inserting a diathermy (electrically activated) needle into the ovary, making between four and eight holes in each ovary.
This caused great excitement, and we performed a lot of these procedures in the mid to late ‘90s with reasonable results in terms of achieving pregnancies for the women treated.
As is the case with many treatments, concerns evolved about ovarian drilling. The risks of the procedure, in addition to those of having a laparoscopy, were shown to be causing adhesions around the ovary, damage to the blood supply of the ovary, and damage to the ovary from the surgeon making too many punctures with the needle. Some Surgeons thought, incorrectly, that if 4 punctures is good, 12 is better.
Within the field of fertility treatment, there are some doctors who advocate LOD enthusiastically, and, I think there is a majority (of whom I am one), who think it is NOT bad treatment, but has a limited place in the treatment of women with PCOS and are trying to conceive.
If you look at the results of comparisons between LOD and ovulation induction with Letrozole and/or FSH, the pregnancy rates are the same. There is a higher rate of multiple pregnancy if you use Letrozole and FSH, which is important, but at Ballarat IVF our multiple birth rate is less than 5%.
At Ballarat IVF, we may speak to our patients regarding LOD if they have had a number of unsuccessful ovulation induction cycles, either with poor, or uncontrolled over response, AND they are not interested in making the transition to IVF with single embryo transfer.
If LOD is to be performed, it must be discussed carefully with the woman before the operation and definitely not a procedure that our Specilaist’s will add in randomly at the time of surgery.
LOD should be performed by a Specialist who has been trained properly, and include the use of surgical equipment specifically designed for the operation.
At Ballarat IVF, we provide more than 500 ovulation induction treatment cycles per year, yet perform one or two LOD treatments for our patients. So, most of the time, if you have PCOS, ovulation induction is all that is required.
~ Dr Russell Dalton