Dysmorphic (T-shaped) Uterus 101 — What Is It, and Who Should Be Checked?

The Normal Uterus

To judge whether a uterus is normal, we first need to agree on the viewing angle. A uterus is roughly two flat sheets of muscle (the myometrium) pressed together front to back, with the uterine cavity, lined by the endometrium, lying between them.

In a woman of reproductive age, the normal uterus is about 7 cm long: the body (corpus) about 4–5 cm and the cervix about 2–3 cm, a corpus-to-cervix ratio of 2 : 1. The uterus develops from the Müllerian ducts, which form the cervix, the corpus uteri and the fallopian tubes.

Finally, in the mid-coronal (front-to-back) view the normal cavity is an inverted triangle, and the muscle bordering it on three sides is of similar thickness.

What Is a Dysmorphic Uterus?

A dysmorphic uterus, also called a T-shaped uterus, is a congenital anomaly caused by abnormal development of the uterine muscle. A muscular layer is too thick and squeezes the cavity narrow, like the letter T.

A dysmorphic uterus is associated with reduced blood supply to the endometrium, abnormal uterine blood flow and contractions, impaired endometrial receptivity, impaired embryo implantation, and poor expansion of the uterus during pregnancy.

Symptoms — Who Should Be Checked?

A woman with a dysmorphic uterus who is not trying to conceive may never be diagnosed, because it rarely causes other gynecological problems that prompt an examination. When it comes to implantation and pregnancy, however, a dysmorphic uterus lowers the chance of implantation and makes it harder for the uterus to stretch to hold a growing baby. If you have any of the following, see a specialist for an assessment.

1. Light periods. Regular cycles but low volume (on the heaviest day, no more than 3 pads, and not even fully soaked).
2. First-trimester miscarriage. A fetus seen but no heartbeat, a blighted ovum, an ectopic pregnancy, or even a positive blood test in which hCG rises for a while and then falls on its own.
3. Hematocrit (Hct) of 40% or above. A woman of reproductive age who menstruates every month normally has an Hct of about 35–39%. If yours is above 40%, take note.
4. Treated by a fertility doctor but still not pregnant. Even after IVF and chromosomally tested embryos, nothing implants. This is how I think about it: about 80% of women of reproductive age have uterine fibroids and about 50% of infertile women have endometriosis — both are easy to find on a routine ultrasound. If the uterus looks perfectly normal, it is worth asking from which angle it is normal. The basic equation for a pregnancy is a normal embryo plus a normal uterus. If normal embryos have been transferred for a while without a pregnancy, I think it is worth taking a closer look at the uterus.

Diagnosing a Dysmorphic Uterus

There are several ways to diagnose a dysmorphic uterus. Each has a different sensitivity, and some depend on the examiner's experience.

Whatever tool is used must reliably show:

• A mid-coronal (front-to-back) view of the uterus
• The external contour of the uterus — whether the outer surface is smooth or indented
• The shape of the internal uterine cavity

Diagnostic hysteroscopy

A camera is passed into the uterine cavity through the vagina and cervix, so there is no surgical incision. With advances in medical imaging, a diagnostic hysteroscope is now only 3–4 mm in diameter. The vaginoscopic technique also avoids a speculum and a tenaculum, so the patient is more comfortable, with less pain.

A normal uterus shows a wide cavity, pink endometrium, and both tubal openings. A dysmorphic uterus shows a narrow cavity running deep like a tunnel, a pale endometrium, and no visible tubal openings.

Panoramic view of the uterine cavity through the hysteroscope

Illustration for explanation; not a photograph of a real patient.

3D transvaginal ultrasound (3D-TVUS)

The uterus can be adjusted to a clear mid-coronal view, so both the external contour and the internal cavity can be assessed with high accuracy. It is affordable, the result is immediate, and it relies less on examiner experience, although extra training in ultrasound is needed. A dysmorphic uterus appears as one uterus with one cavity, whose side walls are thickened so that the cavity is shaped like the letter T.

Appearance on 3D transvaginal ultrasound (3D-TVUS), mid-coronal view

Illustration for explanation; not a photograph of a real patient.

2D transvaginal ultrasound (2D-TVUS)

Only the sagittal (side) view is available, so it is not well suited to diagnosis: the examiner needs advanced skill and must rely on imagination, and angles cannot be measured in the coronal view, so accuracy is poor.

Hysterosalpingography (HSG)

This is the same test used to check the fallopian tubes. It shows the internal cavity but not the external contour, so accuracy is low.

Treatment — Hysteroscopic Metroplasty

There is currently no universally accepted treatment protocol for a dysmorphic uterus, and there are no comparative studies (randomized controlled trials) of treatment results. Even so, specialists worldwide agree that a woman with a dysmorphic uterus who wants to conceive should have surgery to restore a normal cavity through the hysteroscope (hysteroscopic metroplasty). Every study points the same way: pregnancy outcomes improve and miscarriage falls after surgery.

Hysteroscopic metroplasty can be done in the early follicular phase (before ovulation), when the uterine wall is still thin and the uterus does not contract against the instrument. The principle is to cut the left and right uterine muscle apart in a straight line and gradually deepen the cut along that line until the tubal opening (tubal ostium) is seen, looking up from the isthmus. No uterine tissue is removed, unless there is other pathology in the cavity, such as an endometrial polyp or a submucous fibroid.

After surgery

Most patients return to almost normal daily life after surgery, because the scope is passed through the cervix into the cavity and there is no abdominal wound. There may be light vaginal bleeding, especially within the first week.

I recommend no intercourse for one month after surgery, or until the next period arrives, because of the risk of infection of the uterine cavity.

Scarring (adhesions) in the cavity can be prevented by placing the incisions on the left and right sides, where scarring is very unlikely, by placing an anti-adhesion gel in the cavity immediately after surgery, by giving high-dose estrogen to encourage the endometrium to grow over the surgical area, and by giving antibiotics to prevent infection.

Follow-up

After surgery the cavity should be assessed again with a diagnostic hysteroscopy or 3D-TVUS, to see whether its shape has returned to normal.

A diagnostic hysteroscopy by the vaginoscopic technique can be done as an outpatient, takes little time, and causes little or no pain.

Diagnostic hysteroscopy of the same patient with a dysmorphic uterus

Illustration for explanation; not a photograph of a real patient.

After the follow-up assessment, patients can try to conceive naturally or start ovarian stimulation for IVF right away.

If a frozen embryo transfer is planned, I recommend waiting at least 2 menstrual cycles before starting to prepare the uterine lining for transfer.

Treatment Results After Surgery

Our digital hysteroscopy clinic technique makes hysteroscopic surgery safer, more precise and more convenient, restoring the cavity so it is ready to receive an embryo. Nearly 100 patients have had surgery here, and I collected the pregnancy outcomes of patients with a dysmorphic uterus after surgery:

• Patients with a corrected dysmorphic uterus achieved a pregnancy rate of 72.5% within the first year after surgery.
• Of those who became pregnant, 66.7% conceived on their own and 33.3% needed assisted reproductive technology (IVF, ICSI).
• Whether they conceived naturally or through IVF, it took a little over 5 months.

About 5 months in total, whether conceiving naturally or with IVF. Data from nearly 100 patients operated on at LIFE by Dr. Pat.

Summary

• A dysmorphic (T-shaped) uterus is a congenital uterine anomaly that is common in infertile patients and causes infertility and miscarriage.
• Patients often have light periods (no more than 3 pads on the heaviest day, periods shorter than 4 days), repeated miscarriage, or no pregnancy after IVF and transfer of chromosomally normal embryos.
• Diagnosis uses 3D transvaginal ultrasound (3D-TVUS) or hysteroscopy.
• Treatment is hysteroscopic metroplasty.
• Surgery clearly increases the chance of pregnancy and reduces the chance of miscarriage.

References

• Vichinsartvichai P. ความผิดปกติแต่กำเนิดของมดลูก — Congenital Malformation of the Uterus. Chapter 11, Dysmorphic uterus. 1st ed., 2022.
• Coelho Neto MA, Ludwin A, Petraglia F, Martins WP. Definition, prevalence, clinical relevance and treatment of t-shaped uterus: systematic review. Ultrasound Obstet Gynecol. 2021;57(3):366-377. doi:10.1002/uog.23108