The success of in-vitro fertilization and embryo transfer does not mean that this embryo will be implanted with the subsequent initiation of a viable and sustainable pregnancy. The embryo can be successfully implanted in the endometrium only when crosstalk between both of them is successful. The state of the endometrium at the time of implantation is also very critical, along with the quality of the embryo. 4 Evaluation of the endometrium is essential to gauge the endometrial receptivity. Many sophisticated methods of endometrial assessment are available, from endometrial biopsy to endometrial cytokines in uterine flushing, but a simple non-invasive method of ultrasonic endometrial scan became very popular. 13,14
When ovulation occurs, the ovarian follicle turns into a corpus luteum. While the oocytes pass through the fallopian tube, the corpus luteum secretes a steroid hormone, progesterone, which causes structural changes in the endometrium known as decidualization. It actually is the preparation of the endometrium to house the embryo. 3
A total of 689 patients was included, which were divided into two groups based on pregnancy. Inclusion criteria were; the age of the women less than or equal to 38, BMI less than or equal to 28, serum progesterone less than or equal to 4. Group A was the pregnant group, whereas group B was nonpregnant. Both groups were compared for a number of variables. In group, A primary subfertility was 80.0% (72), and secondary subfertility was 20.0% (18), 55.6% (50) were treated along with long protocol and 44.4 % (40) with short, one embryo was transferred in 13.3 % (12), two in 38.8% (35) and 3 or more in 47.8% (43). Thus, the patients in group A were younger. In addition, they have a slightly higher number of follicles, oocytes, and fertilized oocytes, and the cleavage rate was marginally higher than group B.
In group B, primary subfertility was 63.9% (69), and secondary subfertility was 36.1 % (39), 65.7% (71) were treated along with long protocol and 34.3 %(37) with short, one embryo was transferred in 34.3% (37), two in 37.0% (40) and 3 or more in 28.7% (31). BMI was similar in both groups. Endometrial thickness was measured on the decision day, and the pregnancy rate was then calculated for the respective thickness of the endometrium. The pregnancy rate was 6.66 % with the endometrial thickness less than 8 mm and 93.33 % with more than and equal to 8 mm of thickness. In our study, the clinical pregnancy rate in relation to endometrial thickness was 45.45%.
In 1995 Noyes and his colleagues studied the relationship between endometrial thickness and implantation of the embryo after IVF. Implantations of the embryo, clinical pregnancy, and ongoing pregnancy were significantly higher in patients with thicker endometrium P < 0.005). 14
In 2000 De Geyter and his colleagues compared endometrial appearance in 1186 females who underwent assisted reproduction with 205 females who were not treated. The chance of a successful pregnancy was found to be significantly lower in females who showed thinner endometrial thickness.14
In 2003, Kovacs and his colleagues saw the impact of endometrial thickness on the outcome of in-vitro fertilization/ Intracytoplasmic injection. In pregnant women, there was an increased endometrial thickness and a more significant number of follicles, oocytes, fertilized oocytes, and good quality embryos compared to The pregnancy rate was also higher in women with thicker endometrium. 3 Momeni, Rahbar, and Kovanci, 2011 published a Meta-analysis in which the relationship between the thickness of endometrium and IVF outcome was explored among 14 articles selected from 484 articles, all from authentic resources. They concluded that the thicker the endometrium better the IVF outcome. There was a significant difference between the pregnant and nonpregnant groups (p-value 0.001).6 Al-Ghamdi and her co-researchers performed a retrospective cohort in 2008 on a total of 2464 cycles. The pregnancy rate was found to be 35.8%. The pregnancy rate increased as the thickness of the endometrial increases. 16
The day of measurement of endometrial thickness might also influence the association between endometrium thickness and cycle outcome. Implantation and pregnancy rate may improve with increasing the endometrial thickness. 17 In 2012, Zhao, Zhang and Li, studied the relationship between ultrasonically measured thickness and pattern of the endometrium and IVF-ET outcome. They found that consistency and pattern of endometrium had an independent effect on IVF and embryo transfer. Implantation rate and pregnancy rates were 13% and 25.5%, in patients who had endometrial thickness lesser than 7 mm, 33.8% and 52.1% with endometrial thickness more than 7 mm and to ≤ 14 mm and 39.1% and 63.5% with endometrial thickness more than 14 mm. 17
IVF transvaginal ultrasonographic monitoring of endometrial thickness and other changes aids the clinicians while counseling the patients undergoing medically assisted reproduction.6