You are currently browsing the Dr Licciardi blog archives for June, 2008.

The Endometrium Part II

I’ve seen a lot of good questions come across the blog, and I will get to them in the near future.

What makes one woman’s lining thicker than another’s? Probably the only thing we know that makes a difference is uterine surgery. Now don’t everyone panic if you have had uterine surgery. Only very small percentage of women will have a problem, and if you need it, uterine surgery can be a good thing.

The surgery/thickness issue is related to scar tissue. Scarring in the uterus can make the lining thinner. Now there are 2 aspects of this. One is a local thinning. In this case, ultrasound can show a normal lining in part of the uterus, but a thin or absent lining in another area; where the scar is. Sometimes however, even when the scar is in one area, surrounding normal areas may look thin, and these thin areas thicken up after the scar is cut away. In this case it may be that the local scar keeps the 2 sides of the uterus tightly close to each other, and when the scar is cut, the front and back sides are not as close to each other and the lining can grow more thickly.

This last sentence requires a little basic explanation. You see, most people think of the uterus as a globe, round and hollow in the middle. While this is kind of true, the uterus is more like a peanut butter sandwich. The muscle is like the bread, and I call these the sides, or sometimes I say “front and back”, and the lining is like the peanut butter. So imagine areas where there is no peanut butter, the sides are touching in the middle. ( I must say I really hate food analogies, but I can’t think of a better way to say this.) So at hysteroscopy, we cut the scar, and the lining re-grows from the good areas. Of course, during pregnancy the uterus rounds out and becomes the globe.

The second aspect of thin lining and scar tissue is a little different. Here, even though the scar may be in one local area of the uterus, the entire lining gets affected. Last time we spoke about how the lining regenerates from the few glands beneath. Well for some reason, sometimes all of the cells that are supposed to make the new glands don’t work well. As an example, I once had a patient who came to see me because her uterus had been perforated during a hysteroscopy. Now usually such a perforation is localized. It’s a hole in just one spot in the uterus that usually heals well. In her case, yes the hole healed closed, but the lining throughout the entire uterus would not grow thick.

What this may be telling us is that when the uterus becomes damaged in one place, something is released to the surrounding areas of the uterus that permanently affects the ability of the lining to grow well. It may be a result of the injury, or maybe the injury allows for a small infection to start and cause damage. We really do not know how this all works, we just know that in some women, this is the story.

Should you have a hysteroscopy if your lining is really thin? Maybe. You should start with a hysterogram or sonohysterogram. I usually prefer the hysyerogram, but in some patients the sonohysterogram is ok. Some people need both. If these tests show scaring, then yes surgery may be indicated. If the cavities look completely normal, a hysteroscopy may not help because “looking in” without having anything to fix will not do anything to help.

I had one woman with a perfectly normal lining, got pregnant with IVF, and after a vaginal delivery, had a very very thin lining. Who knows, maybe a small infection, uterine tear or neither. A first trimester abortion, or d and c for miscarriage may cause this, but the odds are really low.

And there are some women who have never had surgery or a baby, who just have a thin lining.

Next tine I will discuss if a thin lining matters and ways we try to get the lining thicker.

Please read disclaimer 5/17/06, and thanks again,

Dr. Licciardi

References:

  • Margalioth EJ, Ben-Chetrit A, Gal M, Eldar-Geva T. Investigation and treatment of repeated implantation failure following IVF-ET. Hum Reprod. 2006 Dec; 21(12):3036-43.
  • Y. Shufaro, A. Simon, N. Laufer, M. Fatum. Thin unresponsive endometrium: a possible complication of surgical curettage compromising ART outcome. J Assist Reprod Genet, 25 (2008), pp. 421–425.
  • Laufer N, Simon A. Recurrent implantation failure: current update and clinical approach to an ongoing challenge. Fertil Steril. 2012 May; 97(5):1019-20.
  • Hsieh YY, Tsai HD, Chang CC, et al. Low-dose aspirin for infertile women with thin endometrium receiving intrauterine insemination: a prospective, randomized study. J Assist Reprod Genet 2000; 17:174–177.
  • Chen MJ, Yang JH, Peng FH, et al. Extended estrogen administration for women with thin endometrium in frozen-thawed in-vitro fertilization programs. J Assist Reprod Genet 2006; 23:337–342.
  • Sher G, Fisch JD. Vaginal sildenafil (Viagra): a preliminary report of a novel method to improve uterine artery blood flow and endometrial development in patients undergoing IVF. Hum Reprod 2000; 15:806–809.

The Endometrium

OK,here we go with another topic.
The uterus has 2 basic parts. One is the muscle, also called the myometrium. This gives the uterus its strength, even when stretched thin during pregnancy. Blood travels from the big arteries of the pelvis, through the smaller arteries of myometrium, and during pregnancy from the myometrium to the placenta. Fibroids start to grow from the myometrium.
The other part is the endometrium. This is the layer of glands that line the inside of the uterus. Almost all of the endometrium sheds during menstruation, and then the new glands arise from the small numbers of glands that were left behind. The glands support the pregnancy.
Because the myometrium and endometrium are different tissue types, and of different densities, the two can be seen distinctly via ultrasound.
The ultrasound view of the endometrium changes throughout the cycle. During the period, the endometrium can look very different from day to day and from person to person. By day 2, some women have bled a lot and have shed most of the glands, and therefore their linings look very thin on ultrasound. Some women have not bled much, so most of the lining has not yet shed, and their linings look thicker. This is why I never comment on the endometrium on a day 2 or day 3 scan. If it’s thick it will thin out, if it is thin, it will get thicker as days go by. This is why when some of you ask at the baseline scan, “how does the lining look”, I always say it doesn’t matter how it looks.
The glands then grow thicker day by day and this is the result of increasing exposure to estrogen, which is coming from the growing follicle. This growth phase is also very different from person to person. Some women need very little estrogen to get the lining thicker, and they do not need the estrogen levels to increase with time. All they need is a small amount of estrogen to get the lining to grow, and it will get thicker by itself. In other women, more estrogen is needed. For some women, the thickness can be related to the estrogen level, i.e. the lining can grow to a certain thickness, not more unless the estrogen levels get higher.
The lining stops getting thicker after ovulation, at the start of progesterone production from the follicle, now called the corpus luteum. Progesterone does not make the lining thicker. Progesterone changes the cells of the glands so that they can allow the embryo to grow. Usually the lining stays the same, or it may even get a little thinner after ovulation. Over the next 2 weeks, the lining is undergoing considerable change from day to day, but we can’t see any of these changes on ultrasound.
We can however see a basic change between the pre and post ovulation lining. Before ovulation, the glands look darker, and we can many times see the “triple” pattern, also called the ring. This is shown in the ultraound at the top of the page After ovulation, the emdometrium gets a little brighter, and there is no longer a ring, the pattern is more homogenous.
More to come,
Dr. Licciardi
References:
  • Fritz MA & Speroff L. Clinical Gynecologic Endocrinology and Infertility. Lippincott Williams & Wilkins; Eighth edition; 2010.
  • Norwitz ER, Schust DJ, Fisher SJ. Implantation and the survival of early pregnancy. N Engl J Med 2001; 345(19): 1400-8.
  • Achache H, Revel A. Endometrial receptivity markers, the journey to successful embryo implantation. Hum Reprod Update 2006; 12(6):731-46.
  • N. Noyes, H.C. Liu, K. Sultan, G. Schattman, Z. Rosenwaks. Endometrial thickness appears to be a significant factor in embryo implantation in in vitro fertilization. Hum Reprod, 10 (1995), pp. 919–922.
  • Bergh PA, Navot D. The impact of embryonic development and endometrial maturity on the timing of implantation. Fertil Steril 1992; 58:537-542.