Endometrial lesions caused by catheters used for embryo transfers: a preliminary report

Effect of retained embryos on pregnancy outcomes of in vitro fertilization: a matched retrospective cohort study

OBJECTIVES

To explore the incidence of retained embryos (REs) in embryo transfer (ET) cycles and its effects on pregnancy outcomes in women undergoing in vitro fertilization (IVF).

METHODS

This was a matched retrospective cohort study involving 29,160 ET cycles conducted from March 2016 to February 2021, in which ET cycles without RE were matched to the RE group at a 2:1 ratio. Clinical pregnancy, implantation, miscarriage, and live birth rates were compared between the with-RE and without-RE groups.

RESULTS

Our study showed that the overall incidence of REs was 0.33% (95/29,160). There was a statistically significant difference in RE rate among the operators (P < 0.001), suggesting that the embryo retention rate may be affected by the individual operator. A total of 95 repeated ET cycles due to RE were included in the study group, and 190 ET cycles without RE were matched to the study group (1:2). There were no significant differences between the RE and matched groups in terms of implantation rate (35.6 vs. 38.0%; P = 0.608), clinical pregnancy rate (47.4 vs. 54.7%; P = 0.240), biochemical pregnancy rate (5.3 vs. 4.7%; P = 0.846), miscarriage rate (11.1 vs. 9.6%; P = 0.781), ectopic pregnancy rate (2.2 vs. 1.9%; P = 1.000) or live birth rate (41.1 vs. 48.9%; P = 0.208).

CONCLUSIONS

The present findings demonstrated that immediate retransfer of REs did not significantly affect IVF outcomes, which may provide counselling information for patients when REs are identified and ET is reattempted. The incidence of REs was associated with the operator who expelled the embryos from the catheter. Attention to detail and frequent assessment of the operator's technique may facilitate avoidance of embryo retention.

Individualised luteal phase support in artificially prepared frozen embryo transfer cycles based on serum progesterone levels: a prospective cohort study

STUDY QUESTION

Does an individualised luteal phase support (iLPS), according to serum progesterone (P4) level the day prior to euploid frozen embryo transfer (FET), improve pregnancy outcomes when started on the day previous to embryo transfer?

SUMMARY ANSWER

Patients with low serum P4 the day prior to euploid FET can benefit from the addition of daily subcutaneous P4 injections (Psc), when started the day prior to FET, and achieve similar reproductive outcomes compared to those with initial adequate P4 levels.

WHAT IS KNOWN ALREADY

The ratio between FET/IVF has spectacularly increased in the last years mainly thanks to the pursuit of an ovarian hyperstimulation syndrome free clinic and the development of preimplantation genetic testing (PGT). There is currently a big concern regarding the endometrial preparation for FET, especially in relation to serum P4 levels around the time of embryo transfer. Several studies have described impaired pregnancy outcomes in those patients with low P4 levels around the time of FET, considering 10 ng/ml as one of the most accepted reference values. To date, no prospective study has been designed to compare the reproductive outcomes between patients with adequate P4 the day previous to euploid FET and those with low, but restored P4 levels on the transfer day after iLPS through daily Psc started on the day previous to FET.

STUDY DESIGN, SIZE, DURATION

A prospective observational study was conducted at a university-affiliated fertility centre between November 2018 and January 2020 in patients undergoing PGT for aneuploidies (PGT-A) IVF cycles and a subsequent FET under hormone replacement treatment (HRT). A total of 574 cycles (453 patients) were analysed: 348 cycles (leading to 342 euploid FET) with adequate P4 on the day previous to FET, and 226 cycles (leading to 220 euploid FET) under iLPS after low P4 on the previous day to FET, but restored P4 levels on the transfer day.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Overall we included 574 HRT FET cycles (453 patients). Standard HRT was used for endometrial preparation. P4 levels were measured the day previous to euploid FET. P4 > 10.6 ng/ml was considered as adequate and euploid FET was performed on the following day (FET Group 1). P4 < 10.6 ng/ml was considered as low, iLPS was added in the form of daily Psc injections, and a new P4 analysis was performed on the following day. FET was only performed on the same day when a restored P4 > 10.6 ng/ml was achieved (98.2% of cases) (FET Group 2).

MAIN RESULTS AND THE ROLE OF CHANCE

Patient's demographics and cycle parameters were comparable between both euploid FET groups (FET Group 1 and FET Group 2) in terms of age, weight, oestradiol and P4 levels and number of embryos transferred. No statistically significant differences were found in terms of clinical pregnancy rate (56.4% vs 59.1%: rate difference (RD) -2.7%, 95% CI [-11.4; 6.0]), ongoing pregnancy rate (49.4% vs 53.6%: RD -4.2%, 95% CI [-13.1; 4.7]) or live birth rate (49.1% vs 52.3%: RD -3.2%, 95% CI [-12; 5.7]). No significant differences were also found according to miscarriage rate (12.4% vs 9.2%: RD 3.2%, 95% CI [-4.3; 10.7]).

LIMITATIONS, REASONS FOR CAUTION

Only iLPS through daily Psc was evaluated. The time for Psc injection was not stated and no serum P4 determinations were performed once the pregnancy was achieved.

WIDER IMPLICATIONS OF THE FINDINGS

Our study provides information regarding an 'opportunity window' for improved ongoing pregnancy rates and miscarriage rates through a daily Psc injection in cases of inadequate P4 levels the day previous to FET (P4 < 10.6 ng/ml) and restored values the day of FET (P4 > 10.6 ng/ml). Only euploid FET under HRT were considered, avoiding one of the main reasons of miscarriage and implantation failure and overcoming confounding factors such as female age, embryo quality or ovarian stimulation protocols.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was received. B.C. reports personal fees from MSD, Merck Serono, Ferring Pharmaceuticals, IBSA and Gedeon Richter outside the submitted work. N.P. reports grants and personal fees from MSD, Merck Serono, Ferring Pharmaceuticals, Theramex and Besins International and personal fees from IBSA and Gedeon Richter outside the submitted work. The remaining authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

NCT03740568.

Impact of assisted reproduction techniques on subsequent reproductive performance of dairy heifers and lactating cows

Use of assisted reproduction techniques (ART) such as ovum pick-up for in vitro embryo production (OPU-IVP) and multiple ovulation for embryo transfer (MOET) in livestock has increased in recent years. Objectives of this retrospective cohort study were to evaluate the association between ART and reproductive performance of donor dairy heifers and cows until third lactation. Holsteins donors subjected to MOET (n = 1087) or OPU-IVP (n = 551) were matched with non-donor females (n = 4112) based on date of birth allowing for a maximal difference of 10 days. Binary variables were analyzed using multivariable logistic regression whereas time to first breeding and time to pregnancy were analyzed using multivariable Cox's proportional hazard models and Kaplan-Meier survival curves. Contrasts were built to assess the association between donor status (non-donor vs. MOET + OPU-IVP), type of ART (MOET vs. OPU-IVP) and number of OPU-IVP procedures. Non-donor heifers had greater hazards of first breeding, pregnancy, and first calving compared with donor counterparts. Proportion of pregnant heifers after first breeding was reduced for donors compared with non-donors, which was primarily explained by a reduced proportion of OPU-IVP donors that became pregnant. Although proportion of pregnant cows after first breeding was not associated with ART group during first lactation, hazards of first breeding and pregnancy relative to the end of voluntary wait period were reduced for OPU-IVP donors. During second and third lactations, hazard of first breeding was greater for non-donors compared with donor counterparts. However, proportion of pregnant cows after first breeding and pregnancy hazard were not associated with ART groups. Culling was greater for non-donors compared with donors across all lactations. However, proportion cows culled during first lactation that was attributed to reproductive causes tended to be greater for donor compared with non-donor cows. Assisted reproduction techniques were associated with reduced reproductive performance in dairy heifers and cows but did not increase overall culling.

Investigating the Optimal Time for Intrauterine Human Chorionic Gonadotropin Infusion in Order to Improve IVF Outcome: A Systematic Review and Meta-Analysis

BACKGROUND/AIM

Studies on the impact of intrauterine human Chorionic Gonadotropin (hCG) administration in order to improve the In Vitro Fertilization (IVF) outcome have yielded conflicting results. The aim of the present systematic review and meta-analysis is to investigate whether timing of intrauterine hCG administration prior to embryo transfer affects its efficiency.

MATERIALS AND METHODS

A systematic search of the literature on Pubmed/Medline, Embase and Cochrane databases was performed. Only Randomized Control Trials were included in this meta-analysis.

RESULTS

Live birth rates were not improved following hCG administration (RR=1.13, 95%CI=0.88-1.46, p=0.34) in the pooled results. Combined live birth and ongoing pregnancy rates were borderline statistically significant following hCG administration (RR=1.27, 95%CI=1.00-1.62, p=0.05). Following subgroup analysis regarding live birth and ongoing pregnancy rates, only the 5-12 minutes prior to the embryo transfer group reported a statistically significant improvement.

CONCLUSION

Intrauterine infusion of hCG within an IVF-Intracytoplasmic Sperm Injection (ICSI) cycle improves outcome only when administered 5-12 min prior to embryo transfer.

How do laboratory embryo transfer techniques affect IVF outcomes? A review of current literature

Over the last few years, many studies have focused on embryo selection methods, whereas little attention has been given to the standardization of the procedure of embryo transfer. In this review, several parameters of the embryo transfer procedure are examined, such as the: (i) culture medium volume and loading technique; (ii) syringe and catheters used for embryo transfer; (iii) viscosity and composition of the embryo transfer medium; (iv) environment of embryo culture; (v) timing of embryo transfer; (vi) and standardization of the embryo transfer techniques. The aim of this manuscript is to review these factors and compare the existing embryo transfer techniques and highlight the need for better embryo transfer standardization.

Hysteroscopic evaluation of endocervical and endometrial lesions observed after different procedures of embryo transfer: a prospective comparative study

OBJECTIVE

Endocervical and endometrial damage observed after different procedures of embryo transfer (ET) were investigated using diagnostic hysteroscopy.

STUDY DESIGN

Prospective, descriptive and comparative study, in an Infertility centre, University Hospital. Hundred consecutive infertile patients with a normal uterine cavity, included in an IVF program, were enrolled between May 1st, 2006 and April 30th, 2007. All the patients had a diagnostic hysteroscopy immediately after trial ET using soft ET catheters: (i) IVF Sydney Set (Cook, Limerick, Ireland) (n=27), (ii) Elliocath (Ellios, Paris, France) (n=34), (iii) Frydman classic 4.5 (CCD, Paris, France) (n=19), and rigid ET catheters: Memory Frydman 4.5 (CCD, Paris, France) (n=20). All the procedures were recorded and blindly reviewed. Data were analyzed using a Kruskal-Wallis test for age and severity of endometrial lesions, or Fisher's exact test for binary criteria.

RESULTS

Endocervical lesions were more frequently encountered in the soft (63%) and rigid (85%) Frydman's catheter groups compared to other groups (Elliocath: 29%, IVF Sydney Set: 26%; p<0.0001). Presence of blood on the catheter, and endometrial lesions were significantly less frequent in soft catheter groups compared to the rigid catheter group (p<0.0001). Severe endometrial lesions were less frequently observed when soft catheters were used (85%, 53%, 32%, 11% for Memory Frydman, Frydman classic, Elliocath and IVF Sydney Set, respectively; p<0.0001). The presence of blood on the catheter signed severe endometrial lesions.

CONCLUSION

All ET catheters can lead to endocervical and endometrial damage. Severe endometrial lesions were less frequent when soft catheters were used.

Prospective randomized comparison of Wallace and Labotect embryo transfer catheters

The aim of this study was to compare the clinical performance of Wallace and Labotect embryo transfer catheters in a single assisted reproduction centre. A total of 260 women undergoing embryo transfer were randomized between Wallace and Labotect catheters. When both catheters failed to negotiate the cervical canal, the transfer was accomplished with a stiff catheter. Intention to treat analysis revealed that Wallace and Labotect embryo transfer catheters yielded statistically similar clinical pregnancy (44.6 versus 34.6%), implantation (23.2 versus 18.9%) and ongoing pregnancy (38.5 versus 27.7%) rates. As treated analysis revealed clinical pregnancy rates of 42.5 versus 35.4%, implantation rates of 22.3 versus 20.6% and ongoing pregnancy rates of 36.8 versus 28.3% with Wallace and Labotect catheters respectively. Catheter change due to unsuccessful negotiation of the internal cervical os was significantly more frequently necessary when embryo transfer was first intended with the Wallace than the Labotect catheter (P < 0.001; 33 and 2% respectively). Although not being statistically significant, the observed differences may be regarded as clinically important and may reach statistical significance in larger trials. More trials are necessary before reaching a definitive conclusion regarding the performance of the Labotect embryo transfer catheter.

A review and meta-analysis of prospective trials comparing different catheters used for embryo transfer

OBJECTIVE

To determine the relative efficacy of different types of embryo transfer (ET) catheters.

DESIGN

Systematic review and meta-analysis of prospective randomized, controlled trials comparing at least two different ET catheters.

SETTING

Infertility centers providing treatment with in vitro fertilization/embryo transfer (IVF-ET).

PATIENT(S)

Women undergoing ET.

INTERVENTION(S)

Embryo transfer with soft or hard catheters.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy rate.

RESULT(S)

A total of seven prospective trials were identified that compared soft (Cook or Wallace) catheters with hard (TDT, Frydman, Tomcat, Rocket) catheters. The meta-analysis demonstrated an increased chance of clinical pregnancy when soft ET catheters were used. The TDT catheter was compared against both soft catheters and other hard catheters, showing decreased chance of clinical pregnancy when the TDT catheter was used. Six more prospective trials were identified comparing the Cook and Wallace soft catheters, and the meta-analysis of these data showed no demonstrable difference in clinical pregnancy rates.

CONCLUSION(S)

An increased chance of clinical pregnancy is achieved when soft ET catheters are used. There appears to be little difference between the Cook and Wallace soft catheters.

Implantation sites after embryo transfer into the central area of the uterine cavity

A total of 63 pregnancies (47 singleton, 15 twin, 1 triplet) from intracytoplasmic sperm injection cycles were analysed. In all embryo transfers, the catheter was introduced into the endometrial cavity guided by abdominal ultrasound, with the catheter tip placed at the middle point of the endometrial cavity. Gestational sacs (GS) were located 21-24 days after transfer (gestational age=5 weeks) by two-dimensional and three-dimensional transvaginal ultrasound. The uterine cavity was divided into three parts: upper, middle and lower. Furthermore, the upper region was subdivided into right, middle and left areas, and the middle region was subdivided into right and left areas. The frequency of gestational sacs in each area was evaluated. In singleton pregnancies 66.0% (31/47) of the GS were detected in the upper region, 29.8% (14/47) in the middle region and 4.2% (2/47) in the lower region. In multiple pregnancies (twins and triplet) 45.5% (15/33) of the GS were detected in the upper region, 51.5% (17/33) in the middle region and 3.0% (1/33) in the lower region. In conclusion, the results demonstrate that when embryos are transferred to the central area of the uterine cavity there is an increase in implantation rate in the middle region compared with the rate expected in naturally conceived pregnancies (9-15%).

Assessment of endocervical and endometrial damage inflicted by embryo transfer trial: a hysteroscopic evaluation

The aim was to assess the endocervical and endometrial damage inflicted by embryo transfer trial using office hysteroscopy. Seventy-five consecutive infertile women who underwent office hysteroscopy were enrolled. Hysteroscopy was performed immediately after embryo transfer trial. The relationship between clinical perception of easiness of transfer, presence of blood on the catheter, degree of endocervical and endometrial damage was examined. In the difficult transfer group, minor and moderate endocervical lesions were noted in 35% and 24% of the cases, respectively. The respective figures for the easy transfer group were 19% and 3% (P>.05). There was a statistically significant concordance between the perceived difficulty of transfer and degree of endometrial damage (P<0.05). Of interest, in the easy transfer group, 32% of the patients had minor, 3% moderate and 65% no endometrial damage. The respective figures were 42%, 29% and 29% in the difficult transfer group. There was blood on the catheter in 25%, 56% and 71% of the easy, moderate and difficult transfer groups, respectively. There was a statistically significant concordance between the perceived difficulty of embryo transfer and presence of blood on the catheter (P<0.05). These results suggest that clinical perception of difficulty of transfer and the presence of blood on the catheter are directly associated with endometrial disruption.

Embryo transfer: factors involved in optimizing the success

PURPOSE OF REVIEW

Embryo transfer is arguably the most critical step in assisted reproduction. The purpose of this article is to review the different aspects of the procedure in the light of recent evidence.

RECENT FINDINGS

Randomized trials have shown that significantly higher pregnancy rates are obtained when embryo transfer is performed under ultrasound guidance, the embryos are deposited in the middle part of the uterine cavity, an atraumatic technique is used and when low-dose aspirin is routinely administered following the procedure. Blood in the catheter and leaving the embryos inside it for more than 120 s diminish the pregnancy rate significantly. Air in the catheter, immediate removal of the catheter, performing two transfers in the same cycle, prolonged bed rest, sexual intercourse after embryo transfer or the use of sildenafil do not affect the results. Based on currently available evidence, Cochrane reviews have concluded that the live birth rate is not increased by delaying embryo transfer from day two to three or to the blastocyst stage, and that single embryo transfer leads to lower live birth rates than the transfer of two embryos. The value of a mock transfer a few days before the actual procedure has been challenged as the position of the uterus may change. The effect of holding the cervix with a volsellum, routinely administering antibiotics and the superiority of one catheter over the others is still to be determined.

SUMMARY

Recent studies confirm the importance of the various aspects of embryo transfer. More randomized studies are needed to further evaluate them.

New observations on endometrial physiology after transcervical injection of methylene blue dye

We describe the in vivo features of endometrium stained with methylene blue dye and observed via microhysteroscopy, showing the patterns of endometrial glands and superficial cell changes during the midproliferative, periovulatory, and midluteal phases. These preliminary observations have allowed us to identify a series of changes occurring in the different phases of the ovulatory cycle of potential value in reproductive medicine for specific groups of infertile patients.

Increased implantation and pregnancy rates obtained by placing the tip of the transfer catheter in the central area of the endometrial cavity

The influence of endometrial cavity length (ECL) on implantation and pregnancy rates after 400 embryo transfers was studied prospectively in a population with the indication of IVF/intracytoplasmic sperm injection (ICSI). The tip of the transfer catheter was placed above or below the half point of the ECL in a randomized manner. Two analyses were performed: (i) absolute position (AP); embryo transfers were divided into three groups according to the distance between the end of the fundal endometrial surface and the catheter tip (DTC - distance tip catheter): AP1 (n = 212), 10-15 mm; AP2 (n = 158), 16-20 mm; and AP3 (n = 30), > or =21 mm. (ii) relative position (RP)--embryo transfers were divided into four groups according to their RP [RP = (DTC/ECL) x 100]: RP1 (n = 23), < or =40%; RP2 (n = 177), 41-50%; RP3 (n = 117), 51-60%; and RP4 (n = 83), > or =61%. Analysis based on relative distance revealed significantly higher implantation and pregnancy rates (P < 0.05) in more central areas of the ECL. However, analysis based on absolute position did not reveal any difference. In conclusion, the present results demonstrated that implantation and pregnancy rates are influenced by the site of embryo transfer, with better results being obtained when the catheter tip is positioned close to the middle area of the endometrial cavity. In this respect, previous analysis of the ECL is the fundamental step in establishing the ideal site for embryo transfers.