How does endometriosis affect fertility? Many patients with endometriosis ask this question. This is a very controversial subject with many contradictory studies in the medical literature.
Whether early stage endometriosis with minimal to mild disease has any effect on fertility is not clear. Many women have endometriosis and are not aware of it as evidenced by 1/5 of patients who undergo laparoscopy for tubal ligation are found to have endometriosis and they had no difficulty conceiving. Minimal to mild endometriosis has no or only a minimal effect on fertility.
Performing a laparoscopy in cases of minimal-mild endometriosis including ablating the implants of endometriosis and lysing adhesions may increase the chance of natural fertility. However, performing a laparoscopy simply to find out if a patient has minimal endometriosis is not indicated.
Patients with moderate to severe endometriosis, stage 3 to 4, clearly have decreased fertility. These patients often have at least one endometriosis cyst, an endometrioma, greater than 3 cm. In these cases they have a decrease number of healthy eggs. Unfortunately, the large cyst in the ovary can damage healthy follicles and diminish the number of eggs as they grow. Advanced endometriosis can lead to scar tissue around the ovaries and tubes and cause anatomic abnormalities that can prevent the egg and sperm uniting and an early embryo to make its way back into the uterus.
Laparoscopy to resect a large endometrioma and lyse extensive adhesions can increase the chance of natural conception. However, the surgeon needs to be careful not to damage underlying healthy ovarian tissue when removing the endometrioma.
In patients with large endometriomas where in vitro fertilization is needed, the resection of the endometriosis cyst will not increase the chance of success and in fact may lower the chances of success; many healthy eggs remain below the base of the cyst and removing the cyst could damage or destroy these eggs. Therefore, if an endometriosis cyst is removed it is important not to be too aggressive cauterizing the base of the cyst. Also, there is no advantage to perform a 2nd or 3rd surgery unless it is for other indications e.g. pain.
In terms of natural fertility, medical suppression of the endometriosis following laparoscopy has not been found to be helpful and simply delays the time to conception. In cases where IVF will be performed, there is some data that placing patients on oral contraceptives for 2 to 3 months or using letrozole prior to that IVF cycle may increase pregnancy rates.
The presence of endometriosis may also have an affect on implantation of the embryo. There have been many articles looking at whether endometriosis affects implantation in IVF cycles. Many studies have shown evidence that the rates of an embryo implanting is diminished in patients with endometriosis. However, at the recent annual meeting of the American Society of Reproductive Medicine, a carefully designed and large study of patients undergoing frozen embryo transfers, showed that implantation rates for patients with endometriosis was not any different from implantation rates for patients with other diagnoses.
So, the question whether the presence of early stage endometriosis significantly affects fertility remains a subject of debate. Medical treatment does not increase fertility rate. A fertility drug with intrauterine inseminations may increase fertility and undergoing IVF certainly increases fertility.
Stage 3-4 endometriosis clearly decreases the chance of fertility. A laparoscopy may be helpful for natural conception. However, IVF is generally the most effective treatment in Stage 3-4 endometriosis.
If you have endometriosis and would like to understand how it is affecting your fertility, please contact us for a free initial consultation.