Three-dimensional endometrial volume estimation as a predictor of pituitary down-regulation in an IVF–embryo transfer programme

C. Yaman1,3, T. Ebner1, M. Sommergruber1, J. Hartl1, W. Pölz2 and G. Tews1

1 Women's General Hospital, IVF Unit, Lederergasse 47 and 2 University of Linz, Department for Statistics, Altenbergstr. 69, A-4040 Linz, Austria


    Abstract
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
To examine the role of three-dimensional (3D) volume estimation in predicting pituitary down-regulation in an IVF–embryo transfer programme, 46 women were treated with buserelin acetate for down-regulation prior to and concomitantly with ovarian stimulation. Receiver operating characteristic (ROC) curve analysis was used for statistics. The area under the curve (AUC) provides a measure to show how good (AUC close to 1) or how poor (AUC close to 0.5) a test is. If down-regulation was defined as oestradiol <40, <60 or <80 pg/ml, the AUC of 3D-ultrasound was 0.57, 0.83 and 0.97 respectively. The highest sensitivity (100%) and specificity (93.2%) of 3D-ultrasound was achieved if down-regulation was defined as oestradiol <80 pg/ml (n = 44), with an endometrial volume of 1.9 ml. If down-regulation was defined as oestradiol <60 pg/ml (n = 42) the best combination of highest sensitivity (95.2%) and specificity (75.0%) was obtained with an endometrial volume of 1.9 ml. The comparison of 3D volume calculation with endometrial thickness measurement revealed no significant difference in predicting down-regulation. 3D volume estimation provides a new tool for diagnosing relative hypo-oestrogenism or down-regulation, but it was not superior to two-dimensional ultrasound.

Key words: 3D ultrasound/down-regulation/endometrial volume/hormones/IVF


    Introduction
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Gonadotrophin-releasing hormone (GnRH) analogues have been successfully used in the management of the infertile patient to suppress the pituitary–ovarian axis, prior to and concomitantly with stimulation of follicular growth and induction of ovulation by exogenous gonadotrophins. The possibility of desensitizing the pituitary gland with GnRH analogues and thus inhibiting its capability to respond to oestradiol with an LH surge has prompted many investigators to use GnRH analogues prior to and in combination with human menopausal gonadotrophin (HMG) or FSH. Three different protocols of down-regulation are used – ultralong, long and short. The long protocol is superior in terms of significantly greater follicular recruitment, oocyte recovery and fertilization rates and a significantly greater number of embryos available for transfer (Tan et al., 1992Go; Greenblatt et al., 1995Go). Therefore, it is generally the preferred method, when pituitary down-regulation is to be performed for ovarian stimulation. If the long protocol is used, the hypo-oestrogenism or pituitary down-regulation should be tested before starting ovarian stimulation. Several studies have reported on the diagnosis of pituitary down-regulation using oestradiol status (Ibrahim et al. 1990Go; Seifer et al., 1991Go; Jenkins et al., 1992Go).

The relationship between oestradiol status and endometrial thickness has been proven (Nakamura et al., 1996Go). An endometrial thickness of 6 mm or more was selected to predict the occurrence of withdrawal bleeding after progesterone administration with an accuracy of 95.5%. Furthermore, endometrial thickness was superior to serum oestradiol concentration in predicting withdrawal bleeding (Nakamura et al., 1996Go).

Only one study was available reporting on two-dimensional (2D) endometrial thickness measurement in down-regulated patients (Barash et al., 1998Go). No published data exist on endometrial volume changes measured by transvaginal three-dimensional (3D) ultrasound in patients undergoing pituitary down-regulation for subsequent IVF–embryo transfer. The aim of this study was to document the role of 3D endometrial volume estimation in predicting pituitary down-regulation.


    Materials and methods
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
3D ultrasound and oestradiol examinations were performed in 46 consecutive infertile patients undergoing GnRH analogue-induced pituitary down-regulation in an IVF–embryo transfer programme. The mean age (±SD) of the patients was 32.7 ± 4.6 years. The cause of infertility was unknown in 23% of cases, in 38% it was male factor, and in 39% tubal factor. One patient with pre-existing ovarian cyst was excluded from the study. In all patients, clear morphology of endometrium was obtained with 3D ultrasonography. The down-regulation was started 7 days before expected menstruation with 0.15 mg buserelin nasal spray (Suprefact; Hoechst, Austria) three times daily. Only in four patients was a depot preparation of tryptorelin (3.75 mg Decapeptyl CR; Ferring, Kiel, Germany) administered for down-regulation. The ultrasound and hormone examinations were performed routinely on day 4 or 5 of menstruation and no therapeutic decisions were based on the results of the 3D volume calculations, therefore the study was not subject to institutional review board approval. Oestradiol samples were assayed by Coat-A-Count kits (Diagnostic Products Corporations, Los Angeles, CA, USA). Intra-assay coefficients of variation (CV) of this assay for mean concentrations of 50 and 48 pg/ml were 7.0 ± 3.5 and 8.1 ± 3.9% respectively.

Equipment
All ultrasound scans (2D and 3D) were obtained using the Voluson 530 system (Kretztechnik AG, Zipf, Austria) with transvaginal 5–7.5 MHz volume transducer. First, the uterus was visualized in B mode. Then the system was switched to `volume mode'. After targeting of the endometrium in a vertical plane by the volume box, the slow volume acquisition setting was activated. Volume data were captured by holding the transducer stationary while its crystal electronically swept up to 95° for ~2–3 s. All scanned volumes were stored on a 540 MB hard disk with integrated magneto-optical drive for later measurements and analysis.

The full-planar (contour) method was used for volume measurements. The examinations were done by two observers (C.Y. and M.S.) experienced in pelvic ultrasonography. The measurements were done by only one observer (C.Y.). The volume was computed from several parallel cross-sections from the fundal part of the endometrium to the concentration of the internal os.

Statistical analysis
Receiver operating characteristic (ROC) curve analysis was used. The ROC curve represents the probability of true positive results (sensitivity) as a function of the probability of false positive results (1–specificity).

For this reason, the decision criterion (cut-off point) has to be set at each different point of the decision axis and the sensitivity and specificity for these points have to be calculated. The possible combinations of sensitivity and specificity obtained when varying the cut-off point are combined into the area under the curve (AUC). The AUC (sensitivity/1 – specificity) measures how good (AUC close to 1) or how poor (AUC close to 0.5) a test is.


    Results
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
3D ultrasound
A total of 34 patients had oestradiol <40 pg/ml. In this case, the AUC was 0.57 (Table IGo). The best combination of highest sensitivity (91.2%) and specificity (33.30%) was obtained with an endometrial volume of 1.8 ml.


View this table:
[in this window]
[in a new window]
 
Table I. ROC data and curve of endometrial volume (oestradiol <40 pg/ml; n = 34)
 
If pituitary down-regulation was defined as oestradiol <60 pg/ml, it was achieved in 42 of the 46 patients. The best combination of highest sensitivity (95.2%) and specificity (75.0%) was obtained with an endometrial volume of 1.9 ml. In this case, the AUC was 0.83 (Table IIGo).


View this table:
[in this window]
[in a new window]
 
Table II. ROC data and curve of endometrial volume (oestradiol <60 pg/ml, n = 42)
 
If pituitary down-regulation was defined as oestradiol <80 pg/ml, it was achieved in 44 of the 46 patients. The best combination of the highest sensitivity and specificity was obtained with an endometrial volume of 1.9 ml. Sensitivity was 93.2%, and specificity 100%. The area under the curve was 0.97 (Table IIIGo).


View this table:
[in this window]
[in a new window]
 
Table III. ROC data and curve of endometrial volume (oestradiol <80 pg/ml, n = 44)
 
2D ultrasound
If down-regulation was defined as oestradiol <40 pg/ml, the best combination of the highest sensitivity (91.2%) and specificity (33,3%) was obtained with an endometrial thickness of 5.8 mm. The AUC was 0.60 (Table IVGo).


View this table:
[in this window]
[in a new window]
 
Table IV. ROC data and curve of endometrial thickness (oestradiol <40 pg/ml)
 
If down-regulation was defined as oestradiol <60 pg/ml, the best combination of highest sensitivity (90.0%) and specificity (75.0%) was obtained with an endometrial thickness of 5.8 mm. The AUC was 0.83 (Table VGo).


View this table:
[in this window]
[in a new window]
 
Table V. ROC data and curve of endometrial thickness (oestradiol <60 pg/ml)
 
If down-regulation was defined as oestradiol<80 pg/ml, the best combination was obtained with an endometrial thickness of 5.8 mm (sensitivity 87% and specificity 100%). The AUC was 0.94 (Table VIGo).


View this table:
[in this window]
[in a new window]
 
Table VI. ROC data and curve of endometrial thickness (oestradiol <80 pg/ml)
 

    Discussion
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
3D ultrasound represents a technical development that has led to an improvement in the quality and precision of ultrasound examination. With a vaginal probe, structures can be represented in three planes and the scanned volume can be layered into countless cross-sections. This ultrasonographic innovation has diverse applications, e.g. detection of congenital uterine or fetal anomalies, volume assessment of pelvic or fetal organs (Jurkovic et al., 1995Go; Lee et al., 1996Go).

Two methods are available for 3D volume calculation, the three-distance and the full-planar (contour) method. In a previous study we found good reproducibility for both methods, though the reproducibility for the full-planar method was slightly higher (Yaman et al., 1999Go). With full-planar mode, organs can be visualized in several 2D viewing planes, but in contrast to 2D ultrasound more than one plane can be studied simultaneously. By using this method, the endometrium was investigated by stepping through the volume data in small units.

The assumption that 3D ultrasound can serve as a useful clinical marker for diagnosis of pathologies has been confirmed (Gruobeck et al., 1996Go). In that study, the diagnostic value of endometrial thickness and volume measurements by 3D ultrasound were tested in patients with postmenopausal bleeding. 3D volume was superior to 2D endometrial thickness in predicting endometrial cancer.

The main clinical finding of this study was that the state of relative hypo-oestrogenism after pituitary down-regulation can be diagnosed by 3D ultrasound with a high sensitivity and specificity if an endometrial volume cut-off value from 1.9 ml was used. Conversely, the endometrial thickness measurement by 2D ultrasound was also able to confirm the down-regulation with a high sensitivity if the cut-off value from 5.8 mm endometrial thickness was used.

The predictive value of ultrasound was poor if strong down-regulation or absolute hypo-oestrogenism defined as oestradiol <40 pg/ml was to be achieved.

The question of the proper criteria for the degree of down-regulation of the pituitary–ovarian axis has not yet been answered. It has been reported (Jenkins et al., 1992Go) that oestradiol <55 pg/ml was the 95th percentile established for 727 IVF–embryo transfer cycles without ovarian cysts. However, the optimum value for oestradiol concentration before commencing ovarian stimulation has not been defined, and criteria may vary from oestradiol <20–80 pg/ml among different groups (Sampaio et al., 1991Go; Golan et al., 1994Go; Calhaz-Jorge et al., 1995Go; Dantas et al., 1996Go).

The data of 570 consecutive IVF–embryo transfer cycles in which down-regulation with GnRH analogue long protocol was performed revealed no significant difference in fertilization rates of patients with oestradiol <50 or oestradiol >50 and <100 pg/ml (Calhaz-Jorge et al., 1995Go).

Based on this report and on the results of the present study, it may be assumed that pituitary down-regulation after GnRH analogue administration can be diagnosed by 3D volume calculation. Furthermore, the study documented that diagnosis of pituitary down-regulation can also be performed by 2D endometrial thickness measurements. Similarly, it has been reported (Barash et al., 1998Go) that the state of relative hypo-oestrogenism can be predicted by transvaginal ultrasonographic measurement of endometrial thickness with a positive predictive value of 95.9%. Therefore, routine testing for serum oestradiol concentration seems not to be necessary for diagnosis of down-regulation in patients undergoing IVF–embryo transfer.

The ability to quantify accurately the endometrial volume using 3D ultrasound did not help us to predict the oestrogen status with a higher value than 2D ultrasound. We suggest that endometrial volume calculation by 3D ultrasound provides more accuracy than 2D ultrasound in measurement of asymmetrical organs. After down-regulation, the endometrium is a thin symmetrical structure (Figure 1Go), which may be quantified by 2D ultrasound as well as by 3D ultrasound.



View larger version (96K):
[in this window]
[in a new window]
 
Figure 1. A-Plane: transverse view of endometrium after down-regulation. B-Plane: vertical view demonstrating the planimetric measurement (contour method, endometrial volume: 0.71 ml). C-Plane: frontal view of endometrium.

 
In conclusion, 3D ultrasound provides a new tool in diagnosing pituitary down-regulation but it is not superior to 2D ultrasound.


    Notes
 
3 To whom correspondence should be addressed at: Women's General Hospital Linz, Lederergasse 47, A-4020 Linz, Austria.E-mail: yaman{at}aon.at Back


    References
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Barash, A., Weissman, A., Manor, M. et al. (1998) Prospective evaluation of endometrial thickness as a predictor of pituitary down-regulation after gonadotropin-releasing hormone analogue administration in an in vitro fertilisation program. Fertil. Steril., 69, 496–499.[ISI][Medline]

Calhaz-Jorge, C., Leal, F., Cordeiro, I. et al. (1995) Pituitary down-regulation in IVF cycles: is it necessary to use strict criteria? J. Assist. Reprod. Genet., 12, 615–619.[ISI][Medline]

Dantas, Z.N., Vicino, M., Balmaceda, J.P. et al. (1996) Comparison between nafarelin and leuprolide acetate for in vitro fertilization: preliminary clinical study. Fertil. Steril., 65, 122–126.[ISI][Medline]

Golan, A., Herman A., Soffer, Y. et al. (1994) Ultrasonic control without hormone determination for ovulation induction in in-vitro fertilization/embryo transfer with gonadotrophin-releasing hormone analogue and human menopausal gonadotrophin. Hum. Reprod., 9, 1631–1633.[Abstract]

Greenblatt, E., Mariano, J.S. and Casper, R.F. (1995) Type of stimulation protocol affects oocyte maturity, fertilisation rate, and cleavage rate after intracytoplasmatic sperm injection. Fertil. Steril., 64, 557–563.[ISI][Medline]

Gruobeck, K., Jurkovic, D., Lawton, F. et al. (1996) The diagnostic value of endometrial thickness and volume measurements by three dimensional ultrasound in patients with postmenopausal bleeding. Ultrasound Obstet. Gynecol., 8, 272–276.[ISI][Medline]

Ibrahim, Z.H., Matson, P.L., Buck, P. et al. (1990) Use of buserelin in an IVF programme for pituitary–ovarian suppression prior to ovarian stimulation with exogenous gonadotrophins. Hum. Reprod., 5, 258–262.[Abstract]

Jenkins, J.M., Davies, D.W., Anthony, F. et al. (1992) The detrimental influence of functional ovarian cysts during in-vitro fertilization cycles. Hum. Reprod., 7, 776–780.[Abstract]

Jurkovic, D., Geipel, A., Gruboek, K. et al. (1995) Three-dimensional ultrasound for the assessment of uterine anatomy and detection of congenital anomalies: a comparison with hysterosalpingoraphy and two-dimensional sonography. Ultrasound Obstet. Gynecol., 5, 233–237.[ISI][Medline]

Lee, A., Kratochwil, A., Stümpflen, I. et al. (1996) Fetal lung volume estimation by three-dimensional ultrasound. Am. J. Obstet. Gynecol., 175, 588–592.[ISI][Medline]

Nakamura, S., Douchi, T., Oki, T. et al. (1996) Relationship between sonographic endometrial thickness and progestin induced withdrawal bleeding. Obstet. Gynecol., 87, 722–725.[Abstract/Free Full Text]

Sampaio, M., Serra, V., Miro, F. et al. (1991) Development of ovarian cysts during gonadotrophin-releasing hormone agonists administration. Hum. Reprod., 6, 194–197.[Abstract]

Seifer, D.B., Thornton, K.L., DeCherney, A.H. et al. (1991) Early pituitary desensitization and ovarian suppression with leuprolide acetate is associated with in vitro fertilisation–embryo transfer success. Fertil. Steril., 56, 500–504.[ISI][Medline]

Tan S.L., Kingsland C., Campbell, S., Mills, C. et al. (1992) The long protocol of administration of gonadotropin-releasing hormone agonist is superior to the short protocol for ovarian stimulation for in vitro fertilisation. Fertil. Steril., 57, 810–814.[ISI][Medline]

Yaman, C., Ebner, T., Sommergruber, M. et al. (1999) Reproducibility of three dimensional endometrial volume measurements in patients undergoing ovarian stimulation. Hum. Reprod., 14, 2604–2608.[Abstract/Free Full Text]

Submitted on February 22, 2000; accepted on May 2, 2000.