FERTILITY AND STERILITY
Vol. 54, No.4, October 1990
Printed on acid-free paper in U.S.A.
Copyright© 1990 The American Fertility Society
Dummy embryo transfer: a technique that minimizes the problems of embryo transfer .and improves the pregnancy rate in human in vitro fertilization
Ragaa Mansour, M.D.*t MohamedAboulghar, M.D.*:j: Gamal Serour, M.R.C.O.G.*§ The Egyptian IVF-ET Center, Cairo University, and Al-Azhar University, Cairo, Egypt
Three hundred thirty-five patients selected for in vitro fertilization (IVF) were randomly divided into two groups. Group A (n = 167) was subjected to dummy embryo transfer (ET) before the start of IVF treatment to choose the most suitable catheter for each patient. Group B (n = 168) started their IVF treatment without dummy ET. Embryo transfer technique was difficult in 50 cases (29.8%) in group B, whereas no difficulty was met in group A. Pregnancy rate and implantation rate (22.8%, 7.2%) in group A were significantly higher than in group B (13.1 %, 4.3% ). The lower pregnancy rate in group B is due to the very low pregnancy rate (4%) in difficult ET cases. Dummy ET is a simple procedure that determines the most suitable ET catheter for each patient and avoids unexpected difficult and failed ET. Fertil Steril54:678, 1990
The different factors influencing the pregnancy rate after in vitro fertilization and embryo transfer (IVF-ET) have been studied by many investigators in an endeavor to improve results. 1 •2 One of the most important factors that determine the outcome of IVF is the technique of ET. This last step of the IVF treatment has been examined by few investigators. 2- 4 Most gynecologists involved in IVF programs have certainly noticed the very wide difference in the degree of difficulty in passing the ET catheter through the cervix. Soft ET catheters are preferred over more rigid ones because the latter would be more likely to induce cervical and endometriallaceration.4 However, passing soft catheters through the cervical canal is often difficult and sometimes Received January 22, 1990; revised and accepted June 7, 1990. *The Egyptian IVF-ET Center. t Reprint requests: Ragaa Mansour, Director, The Egyptian IVF-ET Center, 85 Maadi Zeraei Road, Maadi, Cairo, Egypt. :j: Department of Obstetrics and Gynecology, Cairo University. §Department of Obstetrics and Gynecology, Al-Azhar University.
678
Mansour et al.
Dummy embryo transfer
impossible. Failed ET and replacing the embryos using a different catheter is very frustrating and might have many adverse effects on the embryos. Since December 1987 we have been doing a "dummy ET" for patients before starting their IVF treatment to evaluate exactly the passage ofthe ET catheter through the cervical canal, the length and the direction of the uterine cavity, and to determine the most suitable kind of ET catheter to be used for every patient. This study compares the IVF outcome in patients for whom dummy ET was done and those who underwent IVF treatment without performing dummy ET.
MATERIALS AND METHODS
During the period between December 1987 and October 1989, 335 patients selected for IVF were divided into two groups in a controlled, randomized study on an alternate basis. Group A (n = 167) was subjected to dummy ET before the start of IVF treatment. Group B (n = 168) started their IVF treatment without dummy ET. The clinical characteristics of the two groups are summarized in Fertility and Sterility
Table 1
Clinical Characteristics of the Patients Group B GroupA
B1
No. of patients 167 85 83 Age (mean± SD)" 33.98 ± 4.05 34.47 ± 4.24 32.91 ± 5.42 Indication for IVF: Tubal 145 74 73 Tubal+male 11 6 5 Endometriosis 4 2 3 Tubal + ovulatory 7 3 2 Duration of infertility in years (mean± SD) 9.92 ± 4.67 8.50 ± 3.91 8.86 ± 4.72 a
SD, standard deviation.
Table 1. Our protocol for human IVF has been described previously. 5 DummyET
After counseling the patient for IVF, the gynecologist performed the dummy ET by introducing a Wallace catheter (1816 N, H.G.; Wallace LTD., Cholchester, England). It is a soft silicon catheter with an external diameter of 1.6 mm and an end opening, fitted in a more rigid outer Teflon sleeve. If the Wallace catheter did not pass easily, a Craft Catheter (R 57.536; Rocket of London, Watford Herts, England) was used. It is a Teflon catheter with an end opening fitted in an introducing cannula that is rigid but malleable. In difficult cases, when neither the Wallace catheter nor the Craft catheter passed easily, a metal cannula was used to pass through the cervical canal. We use a 20-cm metal cannula with internal and external diameters of 1.6 and 1.9 mm, respectively. The cannula curves gently to follow the curvature of the cervical canal. In few cases, when the introduction of the metal cannula was difficult due to very stenosed internal os or anatomical distortion of the cervix, dilatation under anesthesia up to Hegar 12 was done. All the catheters used for the dummy ET were used previously for ET and resterilized. ET Technique
Embryo transfer was usually done 50 to 60 hours after oocyte pickup. Before the procedure, the patients were given 10 mg Diazepam (Valium; F. Hoffmann-La Roche & Co. LTD, Basle, Switzerland) intravenously. All transfers were done in the dorsal position. The ectocervix and the cervical canal up to the internal os were cleaned of cervical mucus, using a fine sterile cotton swab soaked with Vol. 54, No.4, October 1990
culture medium (Ham's F-10; Gibco Laboratories, Grand Island, NY). Meanwhile, the best four embryos were selected for the transfer and were put together in one organ tissue culture dish (Falcon 3037, Cockeysville, MD) containing Hams F-10 media supplemented with 15% heat-inactivated serum. The choice of the ET catheters was as follows: Group A included 167 patients. The transfer was performed using a Wallace catheter, a Craft catheter, or the metal cannula chosen for each patient according to the previous evaluation of the dummyET. Group B included 168 patients who did not previously have dummy transfer. The transfer was done using either Wallace or Craft catheter. The opinion of the gynecologist about the transfer was recorded as (1) easy when the Wallace or Craft catheter passed immediately through the cervix without resistance and (2) difficult when the gynecologist had to use manipulations and strong push to pass the Wallace or the Craft catheter or when they fail to be passed completely and the metal cannula had to be used. The use of a tenaculum to hold the cervix or the occurrence of bleeding was not necessarily considered as difficult transfer. The subjective evaluation of the procedure by the patient was not taken into consideration as there is a wide range of pain perception among patients. This group was divided randomly on an alternate basis into two subgroups. Group B 1 included 85 cases. The transfer was done using the Wallace catheter. In difficult cases, the metal cannula was used to negotiate the cervical canal, and the Wallace catheter was threaded into it. If the Wallace catheter was kinked or plugged with mucus, the embryos were replaced in anew one. Group B 2 included 83 cases. The transfer was done using the Craft catheter. In difficult cases, the metal cannula was used, and the Craft catheter was passed through it. In case of kinking or plugging of the Craft by mucus or blood, the embryos were replaced in a new one. In all kinds of catheters, the loading was in the following sequence: 15 to 20 JLL of medium, 10 JLL of air, the embryos were loaded in 15 to 20 JLL of transfer medium and withdrawn from the tip of the catheter by aspirating 10 JLL of air. The tip of the catheter was placed approximately 0.5 em from the fundus, and the embryos were gently injected into the uterine cavity. The catheter was immediately checked for retained embryos, blood, or mucus. The length of the uterine cavity was previously measured with ultrasound (US) in group Band diMansour et al.
Dummy embryo transfer
679
Table 2
Results of ET in Group A (Previous Dummy ET) and Group B (No Previous Dummy ET) Total no. ofET
No. of embryos per transfer"
No. of pregnancies
Pregnancy rate
± ± ± ±
38 22 10 12
22.8b 13.1b 18.8 14.5
No. of difficult ET
%
Group A GroupE B1 B2 a b
167 168 85 83
3.9 3.6 3.7 3.5
1.2 1.9 1.5 2.9
Values are means± SD. P = 0.02; x 2 = 5.32 with 1 degree of freedom.
rectly during the dummy ET in group A. After the transfer, the patients remained in bed for about 4 hours, and they usually stayed overnight in the center and were discharged the next morning. The x2 test was used for statistical analysis. RESULTS
The dummy transfer showed that the Wallace catheter passed easily in 110 cases (65%). In the remaining 57 patients, the Craft catheter passed easily in 46 cases (80.7%). However, in 11 cases, neither the Wallace catheter nor the Craft catheter were easily introduced and the metal cannula had to be used. This last group included two cases in which the metal cannula did not pass due to severe stenosis and anatomical distortion of the cervical canal, and dilatation under anesthesia up to Hegar 12 was done. When the ET procedures were done for group A, guided by the previous evaluation of the dummy ET, there was no difficulty met. In group B, there were 118 cases of easy ET and 50 cases of difficult ones. The difficult transfers were met in 32 (37.6%) of ET procedures using the Wallace catheter (group B 1 ) and in 18 cases (21.7%) of ET procedures using the Craft catheter (group B 2 ) as shown in Table 2. The total number of ET procedures was 167 in group A that resulted in 38 pregnancies (22.8%), whereas in group B there were 168 procedures that Table 3
c
50 (29.8)c 32 (37.6) 18 (21. 7)
Values in parentheses are percents.
resulted in 22 pregnancies (13.1 %). The difference was statistically significant (P = 0.02). There was no significant difference between the pregnancy rates in the subgroups B 1 and B 2 (Table 2). The total number of embryos transferred in group A were 651 embryos, resulting in 4 7 implantations (7.2%), whereas in group B, 604 embryos were transferred, resulting in 26 implantations (4.3%). The difference is statistically significant (P = 0.027). The overall pregnancy rate in all cases of easy ET in both groups was 20.4%, which is significantly higher than the pregnancy rate in cases of difficult ET (4%), P = 0.005. Difficult ET resulted in a significantly lower pregnancy rate compared with easy ET performed using the Wall ace catheter, the Craft catheter, or the metal cannula (P = 0.025). In all cases of easy ET, 1,061 embryos were transferred, resulting in 71 implantations (6.7%). In difficult ET, 187 embryos were transferred, resulting in 2 implantations (1% ). The difference is highly significant (P = 0.003) as shown in Table 3. Easy ET, using the Wallace catheter, resulted in a slightly higher pregnancy rate when compared with easy ET using other catheters. The difference, however, was not statistically significant. DISCUSSION
There is a marked discrepancy between oocyte retrieval, fertilization, and cleavage rates that sur-
Implantation Rates in Different Groups
No.ofET
Total no. of embryos transferred
No. of implantations
167 168 285 50
651 604 1061 187
47 26 71 2
Implantation rate %
Group A Group B Easy transfers in both groups Difficult transfers in both groups a
P
680
=
0.027.
Mansour et al.
b
Dummy embryo transfer
p = 0.003.
Fertility and Sterility
pass the 90% range and the pregnancy rate in IVF. There are some mechanical factors that might account for lack of implantation. 6 Careful study of the technique of ET may achieve improvement of the results because minor variations of the transfer technique may impact on the chance of implantation. 7 Our study showed that the pregnancy and implantation rates in group A (22.8%, 7.2%) are significantly higher than in group B (13.1 %, 4.3%). Both groups were comparable in all aspects except that ET procedures were easy in all cases of group A due to individual selection of the most suitable catheter for each patient, which was done according to the previous evaluation of the dummy ET. In group B, difficult ET procedures occurred in 29.8% of cases. The lower pregnancy rate in group B is due to the very low pregnancy rate (4%) in difficult ET cases. In these cases, the passage of the catheter was difficult and manipulations had to be used that often resulted in kinking of the catheter or failure of the transfer. In case of failure, the embryos had to be replaced using another more rigid catheter. This certainly exposes the embryos to adverse effects and subjects the gynecologist and the embryologist to a lot of stress. The better pregnancy rate in cases of easy ET corresponds with earlier published data. 2•3 The other possible value of the dummy ET is the exact measurement of the length ofthe uterine cavity from the fundus to the external os, which we found more accurate than the US measurement that does not follow exactly the curvature of the uterus. Lack of consideration of high fundal placement of embryos may be partially responsible for the higher rate of spontaneous abortion generally observed with IVF-ET. 8 Also, the dummy ET discovers the anatomically distorted cervical canals and abnormally stenosed ones that might benefit from dilatation under anesthesia before the IVF treatment cycle. In some patients, the pelvic adhesions pull the uterus acutely toward one side, and the dummy ET is useful to recognize the direction of the cervical canal. Our results showed that difficult ET procedures had significantly lower pregnancy and implantation rates (4%, 1%) compared with easy ET {20.4%, 6.7%). Soft ET catheters are generally preferred over more rigid ones. 4 This work suggests
Vol. 54, No.4, October 1990
that the best pregnancy rate was achieved when the softest catheter (Wallace) was used and passed easily through the cervical canal. Unfortunately, these soft catheters resulted in the highest rate (37.6%) of difficult ET procedures with its consequences of lowering the pregnancy rate. Therefore, soft catheters are preferred but only when its easy passage through the cervix is assured through the dummyET. Most IVF programs aim at the choice of the most suitable catheter to be used for their patients to achieve the best results. The choice should be individualized for each patient by performing the dummy ET, which is a very simple procedure that avoids the occurrence of unexpected difficult and failed embryo transfers. Acknowledgment. We thank Enas El Attar, Ph.D., Biostatistics, National Cancer Institute, Cairo, Egypt, for her statistical guidance.
REFERENCES 1. Trounson AO: Factors influencing the success of fertilization and embryonic growth in vitro. In Human Conception in Vitro, Edited by RG Edwards, JM Purdy. New York, Academic Press, 1982, p 201 2. Wood C, McMaster R, Rennie G, Trounson A, Leeton J: Factors influencing pregnancy rates following in vitro fertilization and embryo transfer. Fertil Steril43:245, 1985 3. Englert Y, Puissant F, Camus M, Van Hoeck J, Leroy F: Clinical study on embryo transfer after human in vitro fertilization. J In Vitro Fert Embryo Transfer 3:243, 1986 4. Wisanto A, Janssens R, Deschacht J, Camus M, Devroey P, Van Steirteghem AC: Performance of different embryo transfer catheters in a human in vitro fertilization program. Fertil Steril52:79, 1989 5. Aboulghar M, Mansour RT, Serour GI, Sattar MA, Awad MM, Amin Y: Transvaginal ultrasonic needle guided aspiration of pelvic inflammatory cystic masses before ovulation induction for in vitro fertilization. Fertil Steril53:311, 1990 6. Garcia JE: Conceptus transfer. In In Vitro Fertilization, Norfolk, Vol. 1, Edited by HW Jones, GS Jones, GD Hodgen, Z Rosenwaks. Baltimore, Wiliams & Wilkins, 1986, p 215 7. Meldrum DR, Chetkowski R, Steingold KA, de Ziegler D, Cedars MI, Hamilton M: Evolution of a highly successful in vitro fertilization-embryo transfer program. Fertil Steril 48:86,1987 8. Seppala M: The world collaborative report on in vitro fertilization and embryo replacement: current state of the art in January 1984. Ann NY Acad Sc: 442:558, 1985
Mansour et al.
Dummy embryo transfer
681
Vol. 54, No.4, October 1990
Printed on acid-free paper in U.S.A.
Copyright© 1990 The American Fertility Society
Dummy embryo transfer: a technique that minimizes the problems of embryo transfer .and improves the pregnancy rate in human in vitro fertilization
Ragaa Mansour, M.D.*t MohamedAboulghar, M.D.*:j: Gamal Serour, M.R.C.O.G.*§ The Egyptian IVF-ET Center, Cairo University, and Al-Azhar University, Cairo, Egypt
Three hundred thirty-five patients selected for in vitro fertilization (IVF) were randomly divided into two groups. Group A (n = 167) was subjected to dummy embryo transfer (ET) before the start of IVF treatment to choose the most suitable catheter for each patient. Group B (n = 168) started their IVF treatment without dummy ET. Embryo transfer technique was difficult in 50 cases (29.8%) in group B, whereas no difficulty was met in group A. Pregnancy rate and implantation rate (22.8%, 7.2%) in group A were significantly higher than in group B (13.1 %, 4.3% ). The lower pregnancy rate in group B is due to the very low pregnancy rate (4%) in difficult ET cases. Dummy ET is a simple procedure that determines the most suitable ET catheter for each patient and avoids unexpected difficult and failed ET. Fertil Steril54:678, 1990
The different factors influencing the pregnancy rate after in vitro fertilization and embryo transfer (IVF-ET) have been studied by many investigators in an endeavor to improve results. 1 •2 One of the most important factors that determine the outcome of IVF is the technique of ET. This last step of the IVF treatment has been examined by few investigators. 2- 4 Most gynecologists involved in IVF programs have certainly noticed the very wide difference in the degree of difficulty in passing the ET catheter through the cervix. Soft ET catheters are preferred over more rigid ones because the latter would be more likely to induce cervical and endometriallaceration.4 However, passing soft catheters through the cervical canal is often difficult and sometimes Received January 22, 1990; revised and accepted June 7, 1990. *The Egyptian IVF-ET Center. t Reprint requests: Ragaa Mansour, Director, The Egyptian IVF-ET Center, 85 Maadi Zeraei Road, Maadi, Cairo, Egypt. :j: Department of Obstetrics and Gynecology, Cairo University. §Department of Obstetrics and Gynecology, Al-Azhar University.
678
Mansour et al.
Dummy embryo transfer
impossible. Failed ET and replacing the embryos using a different catheter is very frustrating and might have many adverse effects on the embryos. Since December 1987 we have been doing a "dummy ET" for patients before starting their IVF treatment to evaluate exactly the passage ofthe ET catheter through the cervical canal, the length and the direction of the uterine cavity, and to determine the most suitable kind of ET catheter to be used for every patient. This study compares the IVF outcome in patients for whom dummy ET was done and those who underwent IVF treatment without performing dummy ET.
MATERIALS AND METHODS
During the period between December 1987 and October 1989, 335 patients selected for IVF were divided into two groups in a controlled, randomized study on an alternate basis. Group A (n = 167) was subjected to dummy ET before the start of IVF treatment. Group B (n = 168) started their IVF treatment without dummy ET. The clinical characteristics of the two groups are summarized in Fertility and Sterility
Table 1
Clinical Characteristics of the Patients Group B GroupA
B1
No. of patients 167 85 83 Age (mean± SD)" 33.98 ± 4.05 34.47 ± 4.24 32.91 ± 5.42 Indication for IVF: Tubal 145 74 73 Tubal+male 11 6 5 Endometriosis 4 2 3 Tubal + ovulatory 7 3 2 Duration of infertility in years (mean± SD) 9.92 ± 4.67 8.50 ± 3.91 8.86 ± 4.72 a
SD, standard deviation.
Table 1. Our protocol for human IVF has been described previously. 5 DummyET
After counseling the patient for IVF, the gynecologist performed the dummy ET by introducing a Wallace catheter (1816 N, H.G.; Wallace LTD., Cholchester, England). It is a soft silicon catheter with an external diameter of 1.6 mm and an end opening, fitted in a more rigid outer Teflon sleeve. If the Wallace catheter did not pass easily, a Craft Catheter (R 57.536; Rocket of London, Watford Herts, England) was used. It is a Teflon catheter with an end opening fitted in an introducing cannula that is rigid but malleable. In difficult cases, when neither the Wallace catheter nor the Craft catheter passed easily, a metal cannula was used to pass through the cervical canal. We use a 20-cm metal cannula with internal and external diameters of 1.6 and 1.9 mm, respectively. The cannula curves gently to follow the curvature of the cervical canal. In few cases, when the introduction of the metal cannula was difficult due to very stenosed internal os or anatomical distortion of the cervix, dilatation under anesthesia up to Hegar 12 was done. All the catheters used for the dummy ET were used previously for ET and resterilized. ET Technique
Embryo transfer was usually done 50 to 60 hours after oocyte pickup. Before the procedure, the patients were given 10 mg Diazepam (Valium; F. Hoffmann-La Roche & Co. LTD, Basle, Switzerland) intravenously. All transfers were done in the dorsal position. The ectocervix and the cervical canal up to the internal os were cleaned of cervical mucus, using a fine sterile cotton swab soaked with Vol. 54, No.4, October 1990
culture medium (Ham's F-10; Gibco Laboratories, Grand Island, NY). Meanwhile, the best four embryos were selected for the transfer and were put together in one organ tissue culture dish (Falcon 3037, Cockeysville, MD) containing Hams F-10 media supplemented with 15% heat-inactivated serum. The choice of the ET catheters was as follows: Group A included 167 patients. The transfer was performed using a Wallace catheter, a Craft catheter, or the metal cannula chosen for each patient according to the previous evaluation of the dummyET. Group B included 168 patients who did not previously have dummy transfer. The transfer was done using either Wallace or Craft catheter. The opinion of the gynecologist about the transfer was recorded as (1) easy when the Wallace or Craft catheter passed immediately through the cervix without resistance and (2) difficult when the gynecologist had to use manipulations and strong push to pass the Wallace or the Craft catheter or when they fail to be passed completely and the metal cannula had to be used. The use of a tenaculum to hold the cervix or the occurrence of bleeding was not necessarily considered as difficult transfer. The subjective evaluation of the procedure by the patient was not taken into consideration as there is a wide range of pain perception among patients. This group was divided randomly on an alternate basis into two subgroups. Group B 1 included 85 cases. The transfer was done using the Wallace catheter. In difficult cases, the metal cannula was used to negotiate the cervical canal, and the Wallace catheter was threaded into it. If the Wallace catheter was kinked or plugged with mucus, the embryos were replaced in anew one. Group B 2 included 83 cases. The transfer was done using the Craft catheter. In difficult cases, the metal cannula was used, and the Craft catheter was passed through it. In case of kinking or plugging of the Craft by mucus or blood, the embryos were replaced in a new one. In all kinds of catheters, the loading was in the following sequence: 15 to 20 JLL of medium, 10 JLL of air, the embryos were loaded in 15 to 20 JLL of transfer medium and withdrawn from the tip of the catheter by aspirating 10 JLL of air. The tip of the catheter was placed approximately 0.5 em from the fundus, and the embryos were gently injected into the uterine cavity. The catheter was immediately checked for retained embryos, blood, or mucus. The length of the uterine cavity was previously measured with ultrasound (US) in group Band diMansour et al.
Dummy embryo transfer
679
Table 2
Results of ET in Group A (Previous Dummy ET) and Group B (No Previous Dummy ET) Total no. ofET
No. of embryos per transfer"
No. of pregnancies
Pregnancy rate
± ± ± ±
38 22 10 12
22.8b 13.1b 18.8 14.5
No. of difficult ET
%
Group A GroupE B1 B2 a b
167 168 85 83
3.9 3.6 3.7 3.5
1.2 1.9 1.5 2.9
Values are means± SD. P = 0.02; x 2 = 5.32 with 1 degree of freedom.
rectly during the dummy ET in group A. After the transfer, the patients remained in bed for about 4 hours, and they usually stayed overnight in the center and were discharged the next morning. The x2 test was used for statistical analysis. RESULTS
The dummy transfer showed that the Wallace catheter passed easily in 110 cases (65%). In the remaining 57 patients, the Craft catheter passed easily in 46 cases (80.7%). However, in 11 cases, neither the Wallace catheter nor the Craft catheter were easily introduced and the metal cannula had to be used. This last group included two cases in which the metal cannula did not pass due to severe stenosis and anatomical distortion of the cervical canal, and dilatation under anesthesia up to Hegar 12 was done. When the ET procedures were done for group A, guided by the previous evaluation of the dummy ET, there was no difficulty met. In group B, there were 118 cases of easy ET and 50 cases of difficult ones. The difficult transfers were met in 32 (37.6%) of ET procedures using the Wallace catheter (group B 1 ) and in 18 cases (21.7%) of ET procedures using the Craft catheter (group B 2 ) as shown in Table 2. The total number of ET procedures was 167 in group A that resulted in 38 pregnancies (22.8%), whereas in group B there were 168 procedures that Table 3
c
50 (29.8)c 32 (37.6) 18 (21. 7)
Values in parentheses are percents.
resulted in 22 pregnancies (13.1 %). The difference was statistically significant (P = 0.02). There was no significant difference between the pregnancy rates in the subgroups B 1 and B 2 (Table 2). The total number of embryos transferred in group A were 651 embryos, resulting in 4 7 implantations (7.2%), whereas in group B, 604 embryos were transferred, resulting in 26 implantations (4.3%). The difference is statistically significant (P = 0.027). The overall pregnancy rate in all cases of easy ET in both groups was 20.4%, which is significantly higher than the pregnancy rate in cases of difficult ET (4%), P = 0.005. Difficult ET resulted in a significantly lower pregnancy rate compared with easy ET performed using the Wall ace catheter, the Craft catheter, or the metal cannula (P = 0.025). In all cases of easy ET, 1,061 embryos were transferred, resulting in 71 implantations (6.7%). In difficult ET, 187 embryos were transferred, resulting in 2 implantations (1% ). The difference is highly significant (P = 0.003) as shown in Table 3. Easy ET, using the Wallace catheter, resulted in a slightly higher pregnancy rate when compared with easy ET using other catheters. The difference, however, was not statistically significant. DISCUSSION
There is a marked discrepancy between oocyte retrieval, fertilization, and cleavage rates that sur-
Implantation Rates in Different Groups
No.ofET
Total no. of embryos transferred
No. of implantations
167 168 285 50
651 604 1061 187
47 26 71 2
Implantation rate %
Group A Group B Easy transfers in both groups Difficult transfers in both groups a
P
680
=
0.027.
Mansour et al.
b
Dummy embryo transfer
p = 0.003.
Fertility and Sterility
pass the 90% range and the pregnancy rate in IVF. There are some mechanical factors that might account for lack of implantation. 6 Careful study of the technique of ET may achieve improvement of the results because minor variations of the transfer technique may impact on the chance of implantation. 7 Our study showed that the pregnancy and implantation rates in group A (22.8%, 7.2%) are significantly higher than in group B (13.1 %, 4.3%). Both groups were comparable in all aspects except that ET procedures were easy in all cases of group A due to individual selection of the most suitable catheter for each patient, which was done according to the previous evaluation of the dummy ET. In group B, difficult ET procedures occurred in 29.8% of cases. The lower pregnancy rate in group B is due to the very low pregnancy rate (4%) in difficult ET cases. In these cases, the passage of the catheter was difficult and manipulations had to be used that often resulted in kinking of the catheter or failure of the transfer. In case of failure, the embryos had to be replaced using another more rigid catheter. This certainly exposes the embryos to adverse effects and subjects the gynecologist and the embryologist to a lot of stress. The better pregnancy rate in cases of easy ET corresponds with earlier published data. 2•3 The other possible value of the dummy ET is the exact measurement of the length ofthe uterine cavity from the fundus to the external os, which we found more accurate than the US measurement that does not follow exactly the curvature of the uterus. Lack of consideration of high fundal placement of embryos may be partially responsible for the higher rate of spontaneous abortion generally observed with IVF-ET. 8 Also, the dummy ET discovers the anatomically distorted cervical canals and abnormally stenosed ones that might benefit from dilatation under anesthesia before the IVF treatment cycle. In some patients, the pelvic adhesions pull the uterus acutely toward one side, and the dummy ET is useful to recognize the direction of the cervical canal. Our results showed that difficult ET procedures had significantly lower pregnancy and implantation rates (4%, 1%) compared with easy ET {20.4%, 6.7%). Soft ET catheters are generally preferred over more rigid ones. 4 This work suggests
Vol. 54, No.4, October 1990
that the best pregnancy rate was achieved when the softest catheter (Wallace) was used and passed easily through the cervical canal. Unfortunately, these soft catheters resulted in the highest rate (37.6%) of difficult ET procedures with its consequences of lowering the pregnancy rate. Therefore, soft catheters are preferred but only when its easy passage through the cervix is assured through the dummyET. Most IVF programs aim at the choice of the most suitable catheter to be used for their patients to achieve the best results. The choice should be individualized for each patient by performing the dummy ET, which is a very simple procedure that avoids the occurrence of unexpected difficult and failed embryo transfers. Acknowledgment. We thank Enas El Attar, Ph.D., Biostatistics, National Cancer Institute, Cairo, Egypt, for her statistical guidance.
REFERENCES 1. Trounson AO: Factors influencing the success of fertilization and embryonic growth in vitro. In Human Conception in Vitro, Edited by RG Edwards, JM Purdy. New York, Academic Press, 1982, p 201 2. Wood C, McMaster R, Rennie G, Trounson A, Leeton J: Factors influencing pregnancy rates following in vitro fertilization and embryo transfer. Fertil Steril43:245, 1985 3. Englert Y, Puissant F, Camus M, Van Hoeck J, Leroy F: Clinical study on embryo transfer after human in vitro fertilization. J In Vitro Fert Embryo Transfer 3:243, 1986 4. Wisanto A, Janssens R, Deschacht J, Camus M, Devroey P, Van Steirteghem AC: Performance of different embryo transfer catheters in a human in vitro fertilization program. Fertil Steril52:79, 1989 5. Aboulghar M, Mansour RT, Serour GI, Sattar MA, Awad MM, Amin Y: Transvaginal ultrasonic needle guided aspiration of pelvic inflammatory cystic masses before ovulation induction for in vitro fertilization. Fertil Steril53:311, 1990 6. Garcia JE: Conceptus transfer. In In Vitro Fertilization, Norfolk, Vol. 1, Edited by HW Jones, GS Jones, GD Hodgen, Z Rosenwaks. Baltimore, Wiliams & Wilkins, 1986, p 215 7. Meldrum DR, Chetkowski R, Steingold KA, de Ziegler D, Cedars MI, Hamilton M: Evolution of a highly successful in vitro fertilization-embryo transfer program. Fertil Steril 48:86,1987 8. Seppala M: The world collaborative report on in vitro fertilization and embryo replacement: current state of the art in January 1984. Ann NY Acad Sc: 442:558, 1985
Mansour et al.
Dummy embryo transfer
681
