Sonography of the endometrium during conception and nonconception cycles of in vitro fertilization and embryo transfer

Vol. 46, No.3, September 1986 Printed in U.sA.

FERTILITY AND STERILITY Copyright e 1986 The American Fertility Society

Sonography of the endometrium during conception and nonconception cycles of in vitro fertilization and embryo transfer

Arthur C. Fleischer, M.D. *t+ Carl M. Herbert, M.D.:j:§ Glynis A. Sacks, M.D. t Anne Colston Wentz, M.D.:j:§ Stephen S. Entman, M.D.:j: A. Everette James, Jr., M.D. t+ Vanderbilt University Medical Center, Nashville, Tennessee

The thickness of the endometrium was compared in 15 patients who conceived and 15 who did not with an in vitro fertilization and embryo transfer (NF-ET) protocol after ovulation induction with human menopausal gonadotropin Ihuman chorionic gonadotropin (hMGlhCG). There was no statistically significant difference (P = 1.0) in the endometrial thickness in the conception versus the nonconception group. Average estradiol (E~ values and number of mature follicles were also not statistically different in the two groups (P = 0.78, P = 0.81). There was a slightly significant difference in the number of embryos transferred in the conception versus nonconception groups (2.5 versus 1.9, P = 0.005). However, the most significant difference between the conception and nonconception groups was the total number of oocytes retrieved (4.4 versus 2.8, P = 0.005). These findings indicate that there are no sonographically detectable differences in the endometrial thickness in patients who achieve pregnancy versus those that do not when given a similar ovulation induction regimen of hMGlhCG for NF-ET. Fertil Steril46:442, 1986

The "preparedness" of the endometrium is one of several factors which may influence the success or failure of in vitro fertilization and embryo transfer (IVF-ET).l The development of the endometrium is not always accurately predicted by circulating hormone levels. 2

Received December 24, 1985; revised and accepted April 21, 1986. *Reprint requests: Arthur C. Fleischer, M.D., Chief, Ultrasound Section, Department of Radiology and Radiolo~ical Sciences' Vanderbilt University, Nashville, Tennessee 37232. tDepartment of Radiology and Radiological Sciences, Ultrasound Section. :j:Department of Obstetrics and Gynecology. §Center for Fertility and Reproductive Research.

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Fleischer et aI. Sonography of endometrium in IVF

The effect of human menopausal gonadotropin on the endometrium has been studied in a group of IVF patients each of whom had an endometrial biopsy after unsuccessful oocyte fertilization or embryo development. 3 This study showed that human menopausal gonadotropin/human chorionic gonadotropin (hMGtp.CG) stimulation can be associated with a 1- to 2-day advancement of endometrial development. 3 Conversely, in a group of patients undergoing clomiphene citrate induction, the endometrium seemed to demonstrate delayed maturation as depicted by sonography.4 Sonography can now routinely and accurately depict the thickness and texture of the endometrium. 5 , 6 There have been several reports that sugFertility and Sterility

MATERIALS AND METHODS

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Figure 1 Composite graph depicting average daily E2 values and endometrial thickness in conception (C) and nonconception (NC) groups.

gest differences in the thickness and texture of the endometrium, as depicted by sonography, in successful and unsuccessful ovulation induction schemes. 4 -6 The purpose of this study was to investigate the differences in the endometrium that can be detected by sonography in conception versus nonconception IVF-ET cycles in patients undergoing a single hMGlhCG ovulation induction protocol. In addition, the development of the endometrium, as depicted by sonography, was correlated with other factors such as estradiol (E 2) values, the number of large (mature) and small (immature) follicles, the number of oocytes retrieved at laparoscopy, and the number of embryos transferred, any and all of which may influence whether or not pregnancy is achieved in an IVF-ET cycle.

Endometrial thickness was prospectively evaluated in two major groups: those patients who conceived (as evidenced by hCG assays) and those who did not. All patients included in the analysis underwent a standardized hMGlhCG protocol for ovulation induction and underwent embryo transfer. 7 In both groups of patients, daily sonographic evaluation of the endometrium and E2 assays were performed for 5 to 6 days before laparoscopic aspiration of follicles. The day of hCG injection was used as the reference for determining the cycle day. The sonographic estimations and endometrial thicknesses were correlated with the average daily E2 values (Fig. 1). The number of immature (< 15 mm in mean dimension) and mature follicles (> 15 mm), the number of oocytes obtained, and the number of embryos transferred were also noted in each group. The number of immature and mature oocytes retrieved was also statistically evaluated (Table 1). The endometrium was imaged with a Diasonics DS-l (Diagnostic System-I, Diasonics, Inc., Milpitas, CA) utilizing a 3.5-MHz transducer that was focused in the far field. Once the uterus was imaged adequately in long axis using the 20-cm field of view, the image on the screen was electronically magnified. The endometrium was measured by two experienced sonologists (A. C. F., G. A. S.), and the interobserver error was quantified. The endometrium was measured from the echogenic interface of the junction of endometrium and myometrium. Because this linear measurement represents two layers of endometrium, the actual endometrial thickness was taken as half this value. Measurement of the endometrium in this manner has been validated by a previous study,S which analyzed the exact origin of the echoes in the basalis region. Two parameters of the endometrium were considered in the conception versus nonconception groups. One is the thickness on each day before laparoscopy, and the

Table 1. Comparison of Conception and Nonconception Groups Patient groups

Follicles Mean cycle day ---0-::------::-:::---for heG .. 15 mm > 15 mm

Nonconception Conception

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0.92

0.91

0.82

Vol. 46, No.3, September 1986

Mature

Oocytes Immature

2.0 3.3

0.8 1.1

Total

Embryos transferred

2.8 4.4

1.9 2.5

0.005

0.5

Fleischer et aI. Sonography of endometrium in NF

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ence in the patterns of endometrial thickening in the two groups. Interobserver error of measurement of the endometrium was ± 0.5 mm.

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Success or failure to achieve a pregnancy in IVF-ET protocols depends on several interrelated factors.l These include the type of infertility disorder the patient has before seeking treatment,

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Figure 2 Graph depicting the relationship between E2 values and endometrial thicknesses in the conception (C) and nonconception (NC) groups.

other is the change of the endometrial thickness for 5 days before laparoscopy. Statistical analysis was performed with Student's t-test for determination of statistical significance. RESULTS

The data from a total of 30 patients were analyzed. The average number of examinations in the conception group was 4_2 sonograms per patient, whereas it was 4.5 sonograms per patient in the nonconception group_ A total of 129 sonograms were analyzed_ The daily E2 values and the number of mature (> 15 mm in mean dimension) .follicles in the conception group was not statistically different from those of the nonconception group (P = 0.78, P = 0.91) (Fig. 1). The relationship between E2 values and endometrial thickness was similar for both groups (Fig. 2)_ The average number of embryos transferred in the conception group (2_5 per patient) versus the nonconception group (L9 per patient) has a slight statistical significance (P = 0.05)_ The factor that was most statistically significantly different between the nonconception and conception groups was the total number of oocytes retrieved (2.8 versus 4.4) (P = 0.005). There was no statistical difference in endometrial thickness in the group of patients who achieved pregnancy and in those who did not (P = LO) (Figs_ 3 and 4)_ Neither was there a differ-

Figure 3 Conception cycle. (A), Endometrium (between arrows) on hCG day -4 measuring 4 mm. E 2, 301 pg/ml. (B), Endometrium (between arrows) on hCG day - 1 immediately prior to laparoscopy measuring 6 mm. E 2, 1302 pg/ml.

Fleischer et aI. Sonography of endometrium in NF

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favorable" endometrium remains to be established. In a recent study, 6 sonographic depiction of the endometrium was found to be useful in the prediction of success or failure in achieving pregnancy. In this study, the texture of the endometri urn was used as the major sonographic parameter, rather than its thickness. It is believed that an objective

Figure 4 Nonconception cycle. (A), Endometrium (between arrows) on hCG day -4 measuring 3 mm. E 2 , 218 pg/ml. (B), Endometrium (between arrows) on hCG day - 1 measuring 4 mm. E 2 , 323 pg/ml.

the type and regimen of ovulation induction medication used, the number and quality of follicles induced to develop, the pattern and amount of daily E 2 values, and the number and quality of embryos transferred. Endometrial ccpreparedness" may also be a factor that determines whether or not successful implantation occurs. 8 Whether or not sonography is sensitive enough to distinguish between a ccfavorable" versus a ccnon-

Figure 5 Affect of technical factors on sonographic depiction of the endometrium. (A), Relatively hypoechoic endometrium (arrow). (B), Same patient. Identical gain settings, rescanned when the bladder was distended. The endometrium (arrow) appears more echogenic, probably related to the angle at which it is imaged. ·

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parameter such as thickness may be mQre reliable in characterizing the endQmetrium because it seems to be less affected by technique (Fig. 5).5 The measurement Qf thickness- Qf the endometrium used in Qur study is in a range similar to. that repQrted by Glissant. 6 In Qur study, the thickness Qfthe endQmetrium was repQrted as the total endQmetrial thickness Qf the two. layers divided by two.. Thus, Qur measurements represented an average single layer Qf endQmetrium, ,rather than the tQtal thickness Qf the two. layers repQrtedby Glissant. 6 It is impQssible to cQmpletely standardize all IVF-ET factors fQr the evaluatio.n,o.fany Qne vari~ able, such as endQmetrial "preparedness," amQng these. If, hQwever, a single QvulatiQn inductiQn prQtocQI is used and the labQratory techniques are kept cQnstant, SQme reasQnable estimate o.f the rQle Qf endo.metrial "preparedness" as depicted by sQnQgraphy can be Qbtained. We attempted to. accQmplish this by the design Qfthis study. HistQIQgic and sQnQgraphic studies have indicated that the medicatiQn used fQr QvulatiQn inductiQn may alter the timing and sequence Qf endQmetrial deveIQpment. a, 4 In Qne study, endQmetrial biQPsies were perfQrmed in patients who. received hMGlhCG and who. did nQt undergo. ET. EndQmetrial develQpment was accelerated by. 1 to. 2 daYS. 3 In animal studies, it has been shQwn that the implanting blastocyst seems to. prefer an underdevelQped endQmetrium to. an Qverdeveloped endQmetrium. 9 Because endQmetrial develQPment has a rQle in determining the success Qr failure Qf IVF-ET and because sonQgraphy can accurately depict the thickness Qf the endQmetrium, it was believed that this factor CQuld be evaluated. AlthQugh there has been Qne study that suggested a difference between the endQmetrium in thQse patients who. achieved pregnancies versus thQse. who. did nQt,10 Qur data do. nQt shQW a statistically significant difference. The Qnly factors statistically significant between the two. grQUPS were the tQtal number Qf QQcytes retrieved and the number Qf embryQs transferred (Table 1). SQnographic measurement o.f the endo.metrium requires meticulQus sQnQgraphic scanning and accurate measurement Qf the interfaces that rep.resent the endQmetrium Qn the scanner's digital memQry. In preliminary studies,7 it became clear that the endQmetrium was best measured by inclusiQn Qf the echQgenic interfaces, excluding the hYPQechQic halo. that represents the relatively 446

Fleischer et aI. Sonography of endometrium in IVF

cQmpact, inner third vascular layer Qf the myQmetrium. The typical values Qf the endQmetrial thickness befQre laparQscQPy are representative Qf early secretory phase in nQrmal cycles. 8 This is prQbably 'related to. the high level Qf E2 when multiple fQllicles are induced to. develQP. Perhaps SQme o.f the difficulty in accurate measurement Qf the endQmetrium with sQnQgraphy may be related to the assessment Qf its develQPment by measurement, in the anteriQr-PQsteriQr plane, Qf Qnly its thickness. It has been Qur experience that the perceived- thickness Qf the endQmetrium can be altered by the amQunt Qfbladder filling and the angle at ,?/hich the uterus is imaged relative to. the anteriQr abdQminal wall. One prQPQsed solutiQn to. this prQblem is calculatiQn Qf the "endQmetrial vQlume" as determined Qn IQngitudinal and transverse images Qf the uterine CQrpus. 11 Since there seems to be significant interQbserver error in measurement Qf endQmetrial thickness and there dQes nQt appear to be a statistically significant difference in the cQnceptiQn versus nQnco.nceptiQn groups, sonQgraphic evaluatio.n Qf the endQmetrium cannQtbe used alQne as an accuratediscriminatQr in prQgno.sticating whether Qr nQt pregnancy will be achieved. Whether Qr nQt sQnQgraphic depictiQn Qfthe endQmetrium may be a useful parameter awaits a mQre accurate and reliable means Qf measuring its thickness and assessing its textural changes. Acknowledgments. We wish to thank Gary Thieme, M.D., and Wayne Maxson, M.D., for their contributions to this study. David R. Pickens, Ph.D., and Ron Price, Ph.D., are thanked for their assistance in statistical analysis of the data. Monica Harper assisted in manuscript preparation,'Mr. John Bobbitt assisted in photography, and Ms. Bonnie Norman helped with graphic work. REFERENCES 1. DeMouzon J, Lefevre B, Frydeman R, Belaisch-Allart JC,

Guillet-Rosso F, Testart J: Factors affecting human in vitro fertilization: a multifactorial study. Fertil Steril 43:892, 1985 2. Johannisson E, Parker RA, Landgren BM, Diczfalusy E: Morphometric analysis of the human endometrium'in relation to peripheral hormone levels. Fertil Steril 38:564, 1982 3. Garcia J, Acosta A, Hsiu JG, Jones HW: Advanced endo'metrial maturation after ovul'ation induction with human menopausal gonadotropinlhuman chorionic gonadotropin for in vitro fertilization: Fertil Steril 41:31, 1984 4. Fleischer A, Pittaway D, Beard L, Thieme G, Bundy A, James A, Wentz A: Sonographic depiction of endometrial

Fertility and Sterility

changes occuring with ovulation induction. J mtrasound Med 3:344, 1984 5. Fleischer A, Kalemeris G, Machin J, Entman S: Sonography of normal and abnormal endometrium with histopathologic correlation. J mtrasound Med. In press, Aug., 1986 6. Brandt T, Levy E, Grant T, Marut E, Leland J: Endometrial echo and its significance in female infertility. Radiology 157:225, 1985 7. Diamond MP, Wentz AC, Herbert CM, Pittaway DE, Maxson WD, Daniell JF: One ovary or two: difference in ovulation induction, estradiol level and follicular development in a program for in vitro fertilization. Fertil Steril 41:524, 1984

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8. Fleischer A, Kalemeris G, Entman S: Sonographic depiction of the endometrium during normal cycles. J Ultrasound Med BioI 12:271, 1986 9. Noyes R: Normal phases of endometrium. In The Uterus, Edited by H Norris, V Hertiz, N Mal. Baltimore, Williams & Wilkins, 1973, p 110 10. Smith B, Porter R, Ahuja K, Craft I: Ultrasonic assessment of endometrial changes in stimulated cycles in an in vitro fertilization and embryo transfer program. J In Vitro Fert Embryo Transfer 1:223, 1984 11. Smith B: Personal communication, 1985

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