RELATIONSHIP BETWEEN SONOGRAPHIC ENDOMETRIAL THICKNESS AND PROGESTIN-INDUCED WITHDRAWAL BLEEDING

Objective: To determine whether the response to the progestin challeng e test can be predicted from the endometrial thickness measured sonogr aphically. Methods: Progestin challenge tests were performed on 44 wom en with secondary amenorrhea, each of whom also had her endometrial th ickness measured by transvaginal ultrasonography and her serum estradi ol (E2) levels determined. The relationships between the response to t he challenge test, endometrial thickness, and serum E2 levels were stu died, as well as whether the presence or absence of withdrawal bleedin g could be predicted from the endometrial thickness and serum E2 level s. Results: The endometrium was significantly thicker in 32 women who had withdrawal bleeding (10.3 +/- 4.1 mm) than in the 12 who did not b leed (5.0 +/- 1.3 mm) (P < .001). The serum E2 level was also signific antly higher in the positive group: 45.3 +/- 19.4 versus 18.6 +/- 8.0 pg/mL (P < .001). Endometrial thickness of 6.0 mm or more predicted th e occurrence of withdrawal bleeding with an accuracy of 95.5%. Endomet rial thickness was superior to the serum E2 level in predicting withdr awal bleeding. Conclusion: Progestin-induced withdrawal bleeding can b e predicted from the endometrial thickness measured sonographically.