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Thin endometrium: why the womb lining matters
The endometrium is the lining of the womb, where an embryo implants. Before an embryo transfer, a lining of about 7 to 8 millimetres or more on ultrasound is usually wanted. A thinner lining can lower the chance of implantation, but pregnancies do happen with thinner linings, and the cause matters more than one number.
How is the lining measured?
The thickness and appearance of the lining are seen on a vaginal ultrasound during the first half of the cycle, as it grows under the influence of the hormone estrogen. A "triple-line" appearance is often seen in a lining that is building up well.
Common causes of a thin endometrium
- Scarring inside the womb (Asherman syndrome), for example after a D&C, an infection or surgery inside the womb.
- Infection, including genital tuberculosis, which is still seen in India and can damage the lining.
- Low estrogen or a poor response of the lining to estrogen.
- Poor blood flow to the womb lining.
- Sometimes no clear cause is found.
Tests that help
A careful history, a scan, and often a hysteroscopy, in which a thin telescope looks inside the womb, can show scarring and treat adhesions in the same sitting. Tests for tuberculosis may be advised when it is suspected.
Treatment choices
- Treating the cause: removing adhesions at hysteroscopy, or treating an infection.
- Adjusting estrogen: a longer or adjusted course of estrogen before a frozen embryo transfer, so the lining has more time to grow.
- Freezing embryos: if the lining is thin in a fresh IVF cycle, embryos can be frozen and transferred later when the lining is better.
- Other options are sometimes tried, and the evidence for many of them is still limited. Your doctor will explain what is reasonable in your case.
How the lining changes through the cycle
Just after a period the lining is thin. Under estrogen in the first half of the cycle it grows thicker and shows the triple-line pattern. After ovulation, progesterone changes it again, so it looks brighter on the scan and becomes ready for an embryo. This is why the lining is measured at the right point in the cycle, not on any day.
Asherman syndrome in more detail
Scarring inside the womb may follow a D&C, a surgical evacuation after miscarriage or delivery, an infection, or other surgery inside the womb. Periods often become much lighter or stop. At hysteroscopy the scar bands are cut and the cavity opened up; a second look a few weeks later is sometimes advised to check that the scars have not re-formed. Estrogen is often given after the surgery to help the lining regrow.
Genital tuberculosis and the lining
Tuberculosis can affect the lining and the tubes without any chest symptoms. When it is suspected, a sample of the lining may be tested in the lab, for example by culture, histology and a TB-PCR test. If tuberculosis is confirmed, a full course of anti-tuberculosis treatment is given under medical care. Treatment is started on a confirmed or strongly supported diagnosis, not on suspicion alone, because the medicines are long and strong.
What you can do
- Bring the reports of any past D&C, surgery or infection to your appointment.
- Do not stop or change estrogen tablets on your own.
- Ask your doctor about the evidence before trying treatments that are sold as lining boosters; many are unproven.
A thin lining in a frozen embryo transfer
In a frozen transfer, the lining is built with estrogen tablets, patches or gel. If it stays thin, the course may be lengthened, the form of estrogen changed, or the cycle stopped and started again later. A natural-cycle transfer is another option for some women who ovulate regularly. Freezing the embryos means there is no rush: the transfer can wait until the lining is in a better state.
A thin lining is one of the things looked at when IVF has not worked; see our page on repeated IVF failure.
Questions about a thin endometrium
What endometrial thickness is needed for pregnancy?
Before an embryo transfer, a lining of about 7 to 8 millimetres or more is usually wanted. Pregnancies do happen with thinner linings, so the number is read together with the rest of the picture.
Can a thin endometrium be treated?
Often, depending on the cause. Scarring can be removed at hysteroscopy, infections can be treated, and estrogen can be adjusted before a frozen embryo transfer.
Can I get pregnant with a thin lining?
It is possible, but the chance may be lower. Finding and treating the cause usually comes before a transfer.
Why was my embryo frozen instead of transferred because of my lining?
When the lining is thin in a fresh cycle, freezing the embryos and transferring later, once the lining is better, is often the safer choice.
Does a D&C cause a thin lining?
It can, if it causes scarring inside the womb. This is one reason a hysteroscopy is often advised when the lining stays thin.
Can tuberculosis cause a thin lining?
Yes, genital tuberculosis can damage the lining and the tubes. It is tested for when suspected and treated with a full course of medicines if confirmed.
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What you read here explains fertility care in general terms and cannot replace a consultation. Decisions about your own care should be made with a doctor who knows your history and has seen you. We do not carry out or offer sex determination of any kind, which is prohibited by law in India under the PCPNDT Act.