Some women encounter thin endometrial lining and abnormal pattern during natural cycles or during fertility treatment. The implantation of embryos is impaired in women with thin lining and abnormal pattern. Abnormal lining can lead to recurrent implantation failure in young women undergoing IVF after repeated transfer of good quality embryos.
The thickness of the lining appropriate for implantation is commonly defined at 7 to 13mm measured on vaginal ultrasound. The most receptive pattern of the lining of the uterus is a tri-laminar pattern (three line pattern) without little homogenous pattern when visualized shortly before ovulation (pattern 1 and 2 of the photo, Fanchin et al 2000).
Causes for Abnormal Endometrial lining during Fertility Treatment
The two most common abnormalities encountered are
a. Fluid inside the Cavity: fluid may accumulate inside the cavity due to stenosis (narrowing) of the cervix probably because of prior surgery or leak of fluid from a blocked dilted fallopian tube (hydrosalpinx).
b. Thin lining and /or abnormal pattern of endometrium. Possible causes
1. Acquired (Asherman Syndrome): prior D&C (termination of pregnancy), uterin surgery (e.g fibroid surgery) or tuberculosis in women from certain geographical locales. All work through the formation of scar tissue inside the uterus.
2. Idiopathic: no prior cause is identified.
Evaluation of The Uterine Cavity
Proper evaluation of the uterine cavity and lining is an integral component of fertility evaluation and monitoring is also essential during treatment. Methods of evaluation include
i. Vaginal ultrasound for the thickness and pattern during the follicular and luteal phases of the menstrual cycle
ii. Evaluation of the cavity of the uterus using HSG (hysterosalpingogram), saline sonography (water sonogram) or hysteroscopy. Saline sonography is the most invasive and is a very accurate method for evaluation of the cavity and identify if a lesion arising from the wall of the uterus projects into the cavity.
iii. MRI: magnetic resonance imaging can accurately identify abnormalities in the wall of the uterus; fibroids, adenomyosis, congenital anomalies (septum, bicornuate, T shape uterus)
iii. Endometrial biopsy: rarely indicated. The lining of the uterus is sampled and with special stain to detect chronic infection. The value of this testis questionable.
Treatment of Abnormal Endometrial Lining
Many treatments are available to normalize the cavity of the uterus and improve the lining
1. Excision of hydrosalpinx: a dilated blocked fallopian tube especially those seen on ultrasound should be excised to avoid leak of fluid into the uterus. This has the potential of doubling the implantation rate of embryos. Laparoscopy can be used to remove dilated tubes in a minimal access day surery
2. Asherman syndrome: operative hysteroscope can be used to accurately cut the scar tissue and allow the surrounding healthy lining to cove the row area. The lining is treated with estrogen after surgery to promote healing
3. Uterine fibroids and polyps and spetum can be removed using operative hysteroscope.
4. Antibioitics to treat chronic inflammation of the lining of the uterus are seldom effective.
5. During IVF if the lining is not favorable all embryos can be frozen. In subsequent cycle, the lining is prepared with estrogen as long as needed till adequate thickness and pattern is achieved. Progesterone is then started and embryos are thawed in the appropriate time and transferred into the uterus.
6. Sildenafil (viagra) can be given as vaginal tablets but its value is questionable.
7. Gestational carriers can be used if all other methods fail.
Meticulous attention to the condition of the lining and cavity of the uterus is important during fertility treatment of the uterus. Endoscopic surgery and hormone preparation can improve the majority of the linings and increase the chance for embryo implantation
Thin Endometrial Lining During Fertility Treatment by Dr. Amr Azim