Endometrial thickness was greater in cycles resulting in pregnancy than in cycles not resulting in pregnancy (11.9 vs. 11.3 mm, respectively). Clinical pregnancy rates increased gradually from 53% among patients with a lining of <9 mm, to 77% among patients with a lining of ≥16 mm.

The egg begins its five-day travel through a narrow, hollow structure called the fallopian tube to the uterus. As the egg is traveling through the fallopian tube, the level of progesterone, another hormone, rises, which helps prepare the uterine lining for pregnancy.

Therefore we presumed that endometrium also grows rapidly, and that the endometrial volume change, from the implantation day to the late luteal phase of the conception cycle in the same woman, will be detectable by a three-dimensional (3D) ultrasound.

When pregnancy occurs, a fertilized egg will implant into the endometrium while it is at its thickest. Imaging tests done during early pregnancy may show an endometrial stripe of 2 mm or more.

Patients with an endometrial thickness between 7–8 mm had a decreased pregnancy rate, but no significant difference was shown when compared to patients with endometrial thickness in 8-14 mm. Implantation is necessary for a successful pregnancy and requires healthy endometrial receptivity [17].

Pregnancies did not occur when the endometrial thickness was less than 7 mm;[4] however, other studies found that a minimum endometrial thickness of 6 mm is acceptable for implantation. [5–8] Interestingly, Sundström reported a successful pregnancy with an endometrial thickness as little as 4 mm.

Among postmenopausal women with vaginal bleeding, an endometrial thickness ≤ 5 mm is generally considered normal, while thicknesses > 5 mm are considered abnormal4, 5.

NORMAL THICKNESS According to the Radiological Society of North America (RSNA), the endometrium is at its thinnest during menstruation, when it usually measures between 2–4 millimeters (mm) in thickness.

Endometrial thickness of 14 mm or greater was associated with atypical hyperplasia (odds ratio [OR], 4.29; P = . 02), with a negative predictive value of 98.3%. A thickness of 15 mm or greater was associated with carcinoma (OR, 4.53; P = . 03), with a negative predictive value of 98.5%.

[11] reported no pregnancies with an endometrial thickness >12 mm (n = 9). However, Richter et al. [4] and Ai-Ghamdi et al. [23] demonstrated a significant increase in the pregnancy rates as endometrial thickness increased, which was independent of the number and quality of the embryos transferred.

For ovulatory cycles, the mean of endometrial thickness was 7.8 +/- 2.1 mm (3-13 mm) in the follicular phase, 10.4 +/- 1.9 mm (8-13 mm) around ovulation and 10.4 +/- 2.3 mm (8-19 mm) in the luteal phase. The average thickness of endometrium for postmenopausal women without bleeding was 1.4 +/- 0.7 mm (1-5 mm).

The most common treatment is progestin. This can be taken in several forms, including pill, shot, vaginal cream, or intrauterine device. Atypical types of endometrial hyperplasia, especially complex, increase your risk of getting cancer. If you have these types, you might consider a hysterectomy.

Endometrial hyperplasia most often is caused by excess estrogen without progesterone. If ovulation does not occur, progesterone is not made, and the lining is not shed. The endometrium may continue to grow in response to estrogen. The cells that make up the lining may crowd together and may become abnormal.

Endometrial hyperplasia is an increased growth of the endometrium. Unlike a cancer, mild or simple hyperplasia can go away on its own or with hormonal treatment. The most common type of hyperplasia, simple hyperplasia, has a very small risk of becoming cancerous.