***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: BACKGROUND The difficulty of embryo transfer has been reported to affect success rates in some centres , but not in others . Cervical dilatation has been proposed as a means to overcome difficult embryo transfer , but consistent criteria for patient selection are lacking . In a prospect i ve r and omized study , we examined the influence of cervical dilatation 1 - 3 months before embryo transfer on the outcome of  IVF  in cases having difficult embryo transfer in two previously failed IVF cycles . METHODS Two alternative methods of embryo transfer preparation were evaluated in 283 r and omly assigned women having difficult embryo transfers in two previously failed IVF attempts . R and omization was made using a computer-generated r and om number table .  Cervical dilatation  before starting any IVF treatment was used in 145 cases , and no dilatation was performed in 138 cases . RESULTS The cervical dilatation group yielded a significantly higher pregnancy rate than the non-dilated group ( 40 % versus 24 % ; P < 0.01 ) . Likewise , the implantation rate ( 24.1 % versus 14.9 % ; P < 0.01 ) and the live birth rate ( 34.48 % versus 19.56 % ; P < 0.01 ) were significantly higher in the dilatation group than in the non-dilated group . CONCLUSIONS In patients with prior difficult embryo transfer , cervical dilatation 1 - 3 months before embryo transfer lead to an improved pregnancy rate Summary We have investigated a cl aim that bladder filling , by straightening an anteverted uterus into line with the vagina , might facilitate embryo transfer through the cervix after in vitro fertilization . In a r and omized controlled trial in 66 women with and 76 without a filled bladder , we found no significant differences in difficulties encountered at embryo transfer or in the chance of pregnancy BACKGROUND Embryo transfer has changed little since originally described in 1978 . Clinicians rate the type of catheter used as the third most important variable in embryo transfer , but there are no adequately powered r and omized trials . We compared the clinical pregnancy rates with the single lumen catheter ( TCC ) and the double lumen catheter ( CC ) in a r and omized single blind trial . METHODS A total of 650 cycles of women from the Adelaide University reproductive medicine units in Australia were included in this trial . Patients were < 40 years of age undertaking IVF and embryo transfer . Exclusion criteria were : known uterine abnormality , day 3 FSH > 10 IU/l , previous difficult embryo transfer and pre-implantation genetic diagnosis . Cycles were r and omized from numbered sealed envelopes immediately prior to embryo transfer with stratification for fresh or frozen cycles . RESULTS There was a significantly higher pregnancy rate in the group treated with the CC compared with the TCC catheter [ 29.6 versus 20.5 % per embryo transfer , odds ratio ( OR ) = 1.63 ( 95 % confidence interval : 1.14 - 2.30 ) , P = 0.0076 ] . The point estimate for the OR was similar for fresh and frozen cycles . CONCLUSIONS The pregnancy rate was increased by 50 % and this justifies the increased cost of the soft double lumen catheter and the training of clinical staff required OBJECTIVE Given the importance of ET technique during assisted reproductive technology cycles , we evaluated the effect of embryo afterloading subsequent to placement of the ET catheter on pregnancy rates vs. a st and ard direct ET . DESIGN Retrospective cohort analysis . SETTING University-based assisted reproductive technology program . PATIENT(S ) Patients undergoing a fresh nondonor day 3 ET by a single provider over a 1-year period . INTERVENTION(S ) None . MAIN OUTCOME MEASURE(S ) Clinical pregnancy . RESULT ( S ) One hundred twenty-seven patients met inclusion criteria , and the overall pregnancy rate was 46.5 % . There was no difference between the two groups with respect to age , basal FSH , or number of embryos transferred . The ET method used was at the discretion of the provider . There was no difference between the two groups in the presence of blood on the transfer catheter . However , there were significantly more transfer catheters with mucus contamination in the direct transfer group ( 25.58 % vs. 5.95 % ) . The clinical pregnancy rate in the group with ET using the afterloading technique was higher than in the direct ET group ( 52.4 % vs. 34.9 % ) . CONCLUSION ( S ) There was a trend toward an increase in pregnancy rate when an embryo afterloading technique was used . A prospect i ve r and omized trial is needed to examine this issue BACKGROUND The aim of this work was to modify the embryo transfer technique to prevent expulsion of the embryos by exerting gentle mechanical pressure on the cervix using the vaginal speculum . METHODS A total of 639 infertile patients undergoing ICSI were prospect ively r and omized into two groups using sealed dark envelopes . In the study group ( n=325 ) the screw of the vaginal speculum was loosened in order to exert a gentle pressure on the portiovaginalis of the cervix before ejecting the embryos , and was maintained for 7 min afterwards . In the control group ( n=314 ) no pressure was applied on the cervix during embryo transfer and the vaginal speculum was removed after transferring the embryos . RESULTS The clinical pregnancy rate was significantly higher in the study group than in the control group [ 207/325 ( 67 % ) versus 150/314 ( 47.8 % ) ; odds ratio ( OR ) 1.39 ; 95 % confidence interval ( CI ) 1.11 - 1.74 ] . The implantation rate was also significantly higher in the study group [ 304/913 ( 33.3 % ) versus 198/920 ( 21.5 % ) ; OR 1.54 ; 95 % CI 1.26 - 1.89 ] . CONCLUSIONS Applying gentle mechanical pressure on the portiovaginalis of the cervix using the vaginal speculum during and after transferring the embryos significantly improved clinical pregnancy and implantation rates Three hundred thirty-five patients selected for in vitro fertilization ( IVF ) were r and omly 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 Cervical mucus may cover the embryo transfer catheter during passage of the cervical canal , interfering with the correct placement of the embryo(s ) into the uterine cavity . The effect of removal of cervical mucus prior to embryo transfer in IVF/ intracytoplasmic sperm injection ( ICSI ) on live birth rate was studied . The study was set up as a single blind r and omized controlled trial . Couples undergoing IVF/ICSI were r and omly allocated to either removal of cervical mucus prior to embryo transfer , or a mock procedure . R and omization was done with stratification for age , cycle number and method of treatment . Primary outcome was live birth rate .  A total of 317 couples were included and underwent 428 cycles , of which the outcome of 3 cycles was unknown . Baseline characteristics of both groups were comparable . Live birth occurred in 52 of 220 ( 24 % ) cycles in the treatment group and 42 of 205 ( 21 % ) cycles in the control group ( risk difference 3 % , 95 % confidence interval-5- 11 % ) . It is unlikely that removal of cervical mucus prior to embryo transfer has a significant effect on live birth rate . A small effect , however , can not be excluded The aim of this prospect i ve work was to evaluate different catheters and techniques used for embryo transfer . Studies were performed on 105 IVF patients before the start of treatment cycles . Each patient was used as her own control to study the expulsion of methylene blue ( MB ) dye after dummy embryo transfer . Group A ( n = 35 ) underwent the test twice , before and after aspiration of the cervical mucus . Group B ( n = 30 ) underwent the test twice with and without the presence of two air bubbles in the embryo transfer catheter . Group C ( n = 40 ) underwent the test twice using two different catheters , the Wallace and the Craft catheters . The results showed that the dye was extruded at the external os in 57 % of the cases when the cervical mucus was not aspirated compared to 23 % when the mucus was aspirated ( P = 0.01 ) . The dye was extruded in 33 % of the cases with air bubbles in the catheter as compared to 27 % when no air was present ( P > 0.05 ) . When the Wallace catheter was used expulsion occurred in 25.5 % compared to 77.5 % when the Craft catheter was used . We concluded that using soft catheters and complete aspiration of cervical mucus significantly reduced the expulsion of the dye . The presence of air bubbles did not affect rate of expulsion of the dye Abstract Purpose : The present study investigated the effect of bladder distension on  in vitro fertilization and embryo transfer ( IVF-ET ) results . Methods : The study comprised 796 patients after successful transvaginal oocyte pickup and IVF , who , on the basis of bladder filling for ET , were divided into two groups . In group E , 385 patients underwent ET with an empty bladder , and in group F , 411 patients underwent ET with a full bladder . Results : Sixty-four pregnancies were achieved in group E ( 16.6 % ) , compared to 110 pregnancies in group F ( 26.8 % , P=0.006 ) . A similar pregnancy loss rate was observed in both groups , 13 in group E ( 20.3 % ) and 29 in group F ( 26.4 % ; P = NS ) . Conclusions : A significantly higher pregnancy rate was achieved with routine bladder distension before ET , probably attributable to the smooth and easy insertion of the ET catheter This study aim ed to determine whether direct flushing of endometrial cavity with culture media just after cervical irrigation at the time of embryo transfer has any effect on pregnancy rates . A total of 240 women were prospect ively r and omised ; one group of patients ( group 1 ) underwent intrauterine direct flushing of endometrial cavity with culture media just after cervical irrigation at the time of embryo transfer as detected by transabdominal ultrasound and the other group of patients ( group 2 ) had cervical flushing but did not undergo intrauterine flushing .  Pregnancy ( positive human chorionic gonadotrophin ) rates were 57.5 % and 62.9 % for group 1 and group 2 , respectively . Clinical pregnancy ( positive fetal heart rate ) rates were 45.2 % and 51.4 % for group 1 and group 2 , respectively . Implantation rates were 20.0 % and 21.2 % for group 1 and group 2 , respectively . Ongoing pregnancy ( > 12 weeks of pregnancy ) rates were 47.9 % and 47.2 % for group 1 and group 2 , respectively . There were no significant differences in pregnancy rates , clinical pregnancy rates , implantation rates and ongoing pregnancy rates between the two groups . In conclusion , even direct flushing of media into the uterine cavity neither improves nor adversely affects the pregnancy rate One hundred forty-six embryo transfers were carried out in the In Vitro Fertilization ( IVF ) Clinic at St. Pierre Hospital , Brussels , between November 1983 and February 1985 . In each of these cases a series of characteristics of the replacement procedure was systematic ally rates indicated that ( i ) no significant differences appeared among three different operators , ( ii ) the absence or occurrence of cervical bleeding and subjective evaluation of the procedure were related to the chances of establishing a pregnancy , and ( iii ) the duration of replacement had no influence on the outcome of trials . A prospeative r and omized study of 100 replacements showed that ( i ) no better pregnancy rate was obtained by placing patients in the knee-to-chest rather than the dorsal position and ( ii ) the addition of a rigid external sleeve to the catheter did not provide any advantage . A simplified method of replacement is thus advocated The removal of cervical mucus during embryo transfer has been postulated to increase the pregnancy and implantation rates by not interfering with embryo implantation . Even so , this is a time-consuming procedure that may increase the incidence of difficult transfers by removing the naturally lubricant mucus . In addition , any cervical manipulations at the time of embryo transfer may cause unwarranted uterine 
    Output:
    
MAIN RESULTS At the time of ET , there was no evidence of benefit with the following interventions : full bladder , removal of cervical mucus , flushing the endocervical canal or the endometrial cavity .