A gradual increase of endometrial thickness from the day of hCG to the day of ET is predictive of pregnancy outcome in patients with a thin endometrium (< 8mm)

Abstract

An adequate endometrial thickness is necessary for successful implantation. Numerous studies have demonstrated that thin endometrium on the day of hCG is associated with low pregnancy rates. This study was carried out to evaluate the relationship between a gradual increase of endometrial thickness from the day of hCG to the day of ET and pregnancy success and applied to the patients who have less than 8 mm of endometrial thickness on the day of hCG. A prospective study. One hundred two patients who have an endometrial thickness < 8 mm on the hCG day were examined and divided into two different groups by the changes of endometrial thickness. Group I belonged a gradual increase of endometrial thickness from the hCG day to the ET day and Group II with a slow decrease. Luteal phase was supported by 8% progesterone gel daily and 6∼8 mg/day oral E2. Among 102 patients, 46 patients showed a gradual increase of endometrial thickness (Group I) whereas 56 patients showed a slow decrease (Group II). Both groups were similar age, E2 levels on the hCG day, no. of retrieved oocytes and transferred embryos. Clinical PR and ongoing PR were significantly higher in Group I than Group II (P<0.01).Table 1Characteristics and pregnancy outcome.VariableGroup I(Increase)Group II(decrease)No. of patients4656Age36.3 ± 4.336.8 ± 4.6E2 level on the day of hCG(pg/ml)1213 ± 9951334 ± 1029No. of ET2.8 ± 0.72.9 ± 0.8Endometrial thickness(mm) On the hCG day7.8 ± 0.3a7.7 ± 0.3a On the OPU day8.6 ± 0.5b7.8 ± 0.4a On the ET day*9.8 ± 0.6c7.0 ± 0.3b Clinical PR(%)**71.719.6 Ongoing PR(%)**63.07.1Data expressed as means ± SD or % *P< 0.05, **<0.01 and a,b,c < 0.05. Open table in a new tab Data expressed as means ± SD or % *P< 0.05, **<0.01 and a,b,c < 0.05. If endometrial thickness of patients having a thin endometrium (<8 mm) on the day of hCG has gradually increased from the hCG day to the ET day, we would expect high pregnancy rate and ongoing pregnancy rate. Therefore, endometrial thickness on the ET day is important parameter than that on the hCG day in patients with a thin endometrium.