P-258 Impact of Direct Unequal Cleavage (DUC) on embryo development, blastocyst formation and ploidy - artificial intelligence (AI) analysis

Study question

Do DUCs significantly impact embryo development? In particular, morphokinetics, grading, and Pre-implantation Genetic Testing for Aneuploidy (PGT-A) outcome? Is this analysis corroborated by artificial intelligence?

Summary answer

DUC embryos develop slower, have lower rates of blastulation and lower CHLOE (Fairtility) scores for blastulation and implantation. However, occasionally euploid blastocysts form from DUCs.

What is known already

Time-lapse technology enables the identification of DUCs during embryo development. Previous research associates DUCs with poorer blastulation, implantation, and ploidy outcomes. However, DUCs are not routinely annotated in all clinics. Some algorithms, deselect embryos with short second cell cycles; hence, DUCs are rarely transferred. Whether DUC embryos should be automatically discarded or deprioritised is an ongoing debate which leads to inconsistency in clinical practices across fertility centres. AI image processing algorithms may assist embryologists in the identification of DUCs.

Study design, size, duration

A retrospective single-centre study of normally-fertilised embryos cultured in time-lapse incubators throughout 2019--2021. We reviewed 9284 time-lapse videos using an AI image processing tool (CHLOE, Fairtility), and assessed DUC embryo outcomes (ploidy, blastulation, and blastocyst quality). Additionally, we analysed pronuclei data searching for possible causes of DUCs.

Participants/materials, setting, methods

CHLOE (Fairtility) software analysed time-lapse videos identifying pronuclei, DUCs, and blastulation; recording all morphokinetic time points (tPNa,tPNf,t2,t3,t4,t5,t6,t7,t8,t9,tM, tSB,tB,tEB), morphological grades for the inner cell mass (ICM) and trophectoderm, blastocyst size at 116hpi; and assessing the likelihood of blastulation (at 30hpi) and implantation. We evaluated the statistical significance for all variables using t-tests (continuous variables) and chi-squared tests (categorical variables). We quantified the two pronuclei (2PN) detection efficacy using four metrics: accuracy, sensitivity, specificity, and informedness.

Main results and the role of chance

Of all the embryos analysed (n = 9284), 35% showed DUCs (n = 3269). Blastulation was significantly higher in non-DUC versus DUC embryos (76% and 49%, p < 0.0001). Of the embryos that blastulated, ICM quality (A,B,C,D: 24%,13%,19%,21% and 3%,4%,16%,47%, p < 0.001) and trophectoderm quality (20%,21%,15%,23% and 2%,7%,14%,52%, p < 0.0001) were significantly higher in non-DUC than in DUC embryos.

As defined, DUC embryos were significantly quicker at reaching t3 than non-DUC [Mean(SD): 34(15) and 39(10), p < 0.0001], with the minimum times being 4hpi and 13hpi respectively. Interestingly, there was no significant difference in achieving t5 [52(21) and 51(12), NS]. For all other morphokinetic milestones, DUC embryos were 6 hours slower than non-DUC embryos. DUC embryos had an euploidy rate of 27.2% (12/44). Only one DUC embryo was transferred in a double embryo transfer cycle leading to a negative outcome.

Implantation score [0.14(0.24) and 0.46(0.36), p < 0.0001] and blastulation score [0.4(0.46) and 0.75(0.4), p < 0.0001] were lower for DUC embryos than for non-DUC embryos.

CHLOE automatic PN assessment agreed with human annotation in 92% of cases (TP = 388,TN=5,FP=29,FN=7). CHLOE Blastocyst prediction at 30hpi had an AUC of 0.89. The embryologist agreed on 97% of all 483 embryos that CHLOE classified as DUC. Discrepancies arose from CHLOE misclassifying fragments as blastomeres. Further studies warranted.

Limitations, reasons for caution

Differentiating between fragments and blastomeres within the 5 hours from the first division proves challenging for embryologists and, especially, AI algorithms. Hence, some embryos’ DUC status may be misclassified. Additionally, our sample sizes are limited and larger sizes are needed to corroborate our findings, especially those pertaining to ploidy status.

Wider implications of the findings

DUC embryos are associated with poorer outcomes and DUC status should be integrated into embryo classification frameworks. Nevertheless, some DUC embryos prove to be euploid. Hence, DUC embryos should not excluded from culture at cleavage stage and instead be allowed to reach blastocyst stage before assessing their suitability for transfer/vitrification/PGT-A.

Trial registration number

IRB-001C01-01-22

P-472 Extended oocyte cryostorage period is not associated with decreased post-warm survival rate: a retrospective study of 5208 vitrified/warmed oocytes at a single centre

Study question

Is extended oocyte cryostorage period associated with decreased post-warm survival rate?

Summary answer

There is a weak inverse correlation between oocyte cryostorage duration and post-warm survival (r = 0.09, p = 0.01). This equates clinically to a reduction of 0.0003% survival/day.

What is known already

It is widely reported that extended embryo storage is not associated with reduced post-warm survival rates, however there are no such studies in the literature relating to the effect of extended cryostorage duration on oocytes.

Successful outcomes from oocyte vitrification are related to reduced patient age however UK government regulations only permit those with a medical indication to store and use their gametes over 10 years.

With the intended extension of this 10-year limit, it is therefore fair for clinics to expect an increasing population of younger patients choosing to store their oocytes for longer periods.

Study design, size, duration

A retrospective audit of all vitrified/warmed oocyte cycles at a single centre from 2014-2021. A total of 5208 oocytes were included in the study, from 602 treatment cycles.

Participants/materials, setting, methods

Patients of all ages were included in the study. Data was obtained retrospectively from IDEAS V6.0 at CRGH, UK. All oocytes were vitrified/warmed according to the Irvine Scientific/Kitazato media protocols, with all other protocols excluded. Data was analysed using IBM® SPSS® Statistics V24. Kendall’s tau-b and Spearman’s Rho correlation coefficients measured the strength and direction of association between variables. A linear regression model was used to establish the effect of duration on survival per day.

Main results and the role of chance

The median age at oocyte vitrification was 31 years (range 18-45 years, LQR=25 years, UQR=37 years). There was a median of 8 oocytes thawed per case (LQR=6, UQR 11 oocytes) with a median of 6 oocytes surviving (LQR=3, UQR=9 oocytes). The median survival rate across all ages was 81% (LQR=58%, UQR=100%). There was no significant difference in oocyte survival rate between age categories (<35 years vs > 35 years; p = 0.137, n = 414 & 188 respectively). Increasing age was however, significantly correlated with fewer oocytes vitrified (r = 0.283, p = 0.001).

There is a weak inverse correlation between oocyte cryostorage duration and post-warm survival (r = 0.09). This correlation reaches statistical significance (p = 0.01), however this equates clinically to a reduction of 0.0003% survival rate per day.

No significant difference was observed in post-warm oocyte survival rate across duration of vitrification categories (≤3 years vs 4-5 years vs > 5 years; p = 0.154, n = 416, 141 & 45 cases respectively).

The median duration for which oocytes remained in cryostorage was 565 days (1.6 years) (LQR & UQR=233 days (0.64 years) and 1390 days (3.8 years) respectively).

Limitations, reasons for caution

Although retrospective, the study benefits from many cycles, all of which were carried out at the same unit, using the same vitrification/warming media protocol. Limitations of this study include a relatively short median cryostorage duration time which could be masking the true effect of duration on post-warm oocyte survival.

Wider implications of the findings

Following a public consultation in 2020 regarding the 10-year storage limit for gametes and embryos, the UK Government proposed changes the current legislation which will allow patients to extend cryostorage beyond 10 years without a medical indication. To our knowledge, this is the first study to lend support this movement.

Trial registration number

IRB-001C03-01-22

The REBOA window: a cadaveric study delineating the optimum site for austere cannulation of the femoral artery for resuscitative endovascular balloon occlusion of the aorta

INTRODUCTION

Haemorrhage is the major cause of early mortality following traumatic injury. Patients suffering from non-compressible torso haemorrhage are more likely to suffer early death. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) can be effective in initial resuscitation; however, establishing swift arterial access is challenging, particularly in a severe shock. This is made more difficult by anatomical variability of the femoral vessels.

METHODS

The femoral vessels were characterised in 81 cadaveric lower limbs, measuring specifically the distance from the inferior border of the inguinal ligament to the distal part of the origin of the profunda femoris artery (PFA), and from the distal part of the origin of the PFA to where the femoral vein lies posterior to and is completely overlapped by the femoral artery.

RESULTS

The femoral vein lay deep to the femoral artery at a mean distance of 105 mm from the inferior border of the inguinal ligament. The PFA arose from the femoral artery at a mean distance of 51.1 mm from the inguinal ligament. From the results, it is predicted that the PFA originates from the common femoral artery approximately 24 mm from the inguinal ligament, and the femoral vein is completely overlapped by the femoral artery by 67.7 mm distal from the inguinal ligament, in 95% of subjects.

CONCLUSIONS

Based on the results, proposed is an 'optimal access window' of up to 24 mm inferior to the inguinal ligament for common femoral arterial catheterisation for pre-hospital REBOA, or more simply within one finger breadth.

The use of Palma's procedure in the salvage therapy for a leiomyosarcoma of the right pelvic sidewall: an intraoperative multidisciplinary approach

Leiomyosarcomas of the ovary and broad ligament are relatively rare. Less than 50 cases of primary ovarian and broad ligament leiomyosarcomas have been reported. The prognosis is poor, with late-stage disease being a problem in the majority of cases. It is difficult to determine the exact role of surgery, chemotherapy, and radiotherapy in the management of these tumors. So far, no cases of ovarian or broad ligament leiomyosarcomas have been reported where primary surgery for the sarcoma had to be combined with a Palma's procedure. We report a case of a right pelvic sidewall leiomyosarcoma with involvement of 10 cm of the right external iliac vein. A review of the imaging preoperatively did not suggest involvement of the venous system. Resection of the pelvic mass was carried out and a Palma's procedure was performed by the vascular surgeon. Histology reported an incompletely excised high-grade leiomyosarcoma. Chemotherapy was given postoperatively. Imaging at 12 months after surgery showed a patent vascular graft and no evidence of recurrence. There was no clinical evidence of recurrence at 21 months postsurgery.

The use of Palma's procedure in the salvage therapy for a leiomyosarcoma of the right pelvic sidewall: an intraoperative multidisciplinary approach

Leiomyosarcomas of the ovary and broad ligament are relatively rare. Less than 50 cases of primary ovarian and broad ligament leiomyosarcomas have been reported. The prognosis is poor, with late-stage disease being a problem in the majority of cases. It is difficult to determine the exact role of surgery, chemotherapy, and radiotherapy in the management of these tumors. So far, no cases of ovarian or broad ligament leiomyosarcomas have been reported where primary surgery for the sarcoma had to be combined with a Palma's procedure. We report a case of a right pelvic sidewall leiomyosarcoma with involvement of 10 cm of the right external iliac vein. A review of the imaging preoperatively did not suggest involvement of the venous system. Resection of the pelvic mass was carried out and a Palma's procedure was performed by the vascular surgeon. Histology reported an incompletely excised high-grade leiomyosarcoma. Chemotherapy was given postoperatively. Imaging at 12 months after surgery showed a patent vascular graft and no evidence of recurrence. There was no clinical evidence of recurrence at 21 months postsurgery.

The ecotopes and evolution of triatomine bugs (triatominae) and their associated trypanosomes

Triatomine bug species such as Microtriatoma trinidadensis, Eratyrus mucronatus, Belminus herreri, Panstrongylus lignarius, and Triatoma tibiamaculata are exquisitely adapted to specialist niches. This suggests a long evolutionary history, as well as the recent dramatic spread a few eclectic, domiciliated triatomine species. Virtually all species of the genus Rhodnius are primarily associated with palms. The genus Panstrongylus is predominantly associated with burrows and tree cavities and the genus Triatoma with terrestrial rocky habitats or rodent burrows. Two major sub-divisions have been defined within the species Trypanosoma cruzi, as T. cruzi 1 (Z1) and T. cruzi 2 (Z2). The affinities of a third group (Z3) are uncertain. Host and habitat associations lead us to propose that T. cruzi 1 (Z1) has evolved in an arboreal, palm tree habitat with the triatomine tribe Rhodniini, in association with the opossum Didelphis. Similarly we propose that T. cruzi (Z2) and Z3 evolved in a terrestrial habitat in burrows and in rocky locations with the triatomine tribe Triatomini, in association with edentates, and/or possibly ground dwelling marsupials. Both sub-divisions of T. cruzi may have been contemporary in South America up to 65 million years ago. Alternatively, T. cruzi 2 (Z2) may have evolved more recently from T. cruzi 1 (Z1) by host transfers into rodents, edentates, and primates. We have constructed a molecular phylogeny of haematophagous vectors, including triatomine bugs, which suggests that faecal transmission of trypanosomes may be the ancestral route. A molecular clock phylogeny suggests that Rhodnius and Triatoma diverged before the arrival, about 40 million years ago, of bats and rodents into South America.

The epidemiology of louping-ill, a tick borne infection of red grouse (Lagopus lagopus scoticus)

The epidemiology of louping-ill in red grouse was studied in northern Britain concentrating on the possible role of other species and mechanisms of disease persistence. This tick borne viral disease caused heavy mortality in red grouse, particularly chicks. Louping-ill induced mortality reduced the strength of the density dependence that generates the tendency of grouse populations to cycle and in some populations may cause population sinks. Four routes of transmission were examined and non-viraemic transmission of virus between ticks cofeeding on hares was considered significant. Field data supported the hypothesis that disease dynamics is influenced greatly by mountain hares, both as passive amplifiers and as hosts for the tick vector. Genetic variation in louping-ill within Britain was small.

Transmission of louping ill virus between infected and uninfected ticks co-feeding on mountain hares

Most of the data on oral infection of ticks by louping ill virus have been obtained from experiments in which animals were infected by syringe inoculation with infectious material. Using infected ticks to mimic the natural situation, we have demonstrated that louping ill (LI) virus transmission can occur from infected to uninfected Ixodes ricinus feeding in close proximity on mountain hares (Lepus timidus). Under these conditions the hares developed either low or undetectable viraemias. Highest prevalence of LI virus infection was observed in recipient nymphs which had fed to repletion between days 3 and 7 post-attachment of virus-infected adults; following engorgement, 56% of nymphs acquired virus. These results demonstrate the efficient transmission of LI virus between co-feeding ticks on naive mountain hares. However, when ticks were allowed to co-feed on virus-immune hares a significant reduction in the frequency of infection was observed. Neither red deer (Cervus elaphus) nor New Zealand White rabbits supported transmission of LI virus. The significance of virus transmission between cofeeding ticks on LI virus epidemiology is discussed.

Persistence and transmission of tick-borne viruses: Ixodes ricinus and louping-ill virus in red grouse populations

The population dynamics of tick-borne disease agents and in particular the mechanisms which influence their persistence are examined with reference to the flavivirus that causes louping-ill in red grouse and sheep. Pockets of infection cause heavy mortality and the infection probably persists as a consequence of immigration of susceptible hosts. Seroprevalence is positively associated with temporal variations in vectors per host, although variation between areas is associated with the abundance of mountain hares. The presence of alternative tick hosts, particularly large mammals, provides additional hosts for increasing tick abundance. Grouse alone can not support the vectors and the pathogen but both can persist when a non-viraemic mammalian host supports the tick population and a sufficiently high number of nymphs bite grouse. These alternative hosts may also amplify virus through non-viraemic transmission by the process of co-feeding, although the relative significance of this has yet to be determined. Another possible route of infection is through the ingestion of vectors when feeding or preening. Trans-ovarial transmission is a potentially important mechanism for virus persistence but has not been recorded with louping-ill and Ixodes ricinus. The influence of non-viraemic hosts, both in the multiplication of vectors and the amplification of virus through non-viraemic transmission are considered significant for virus persistence.

Microinjection of human placenta. I: Techniques

An apparatus is described which has been used successfully to microinject the syncytiotrophoblast of chorionic villi, the mesenchymal core of chorionic villi, and cultured cells grown from first-trimester human trophoblast. It will accurately and repeatedly pulse picolitre quantities of injectate from the micropipette.

Microinjection of human placenta. II: Biological application

Using microinjection of probes detectable by epifluorescence light microscopy and electron microscopy we have provided direct evidence that syncytiotrophoblast is a true syncytium. We have investigated the freedom of movement of probes injected into the syncytiotrophoblast. These probes appear to move relatively extensively within the cytosolic compartment which forms a 'maze' through the membrane-bounded organelles and reticula of the syncytium. Thus mathematical models of certain forms of transepithelial transport based on simple mean and harmonic mean histologically measured thickness of epithelia are unlikely to describe the transepithelial transport pathway of at least some larger molecules, particulates and organelles with great accuracy. Microinjection of probes directly into the mesenchymal core of chorionic villi has been used to demonstrate extensive freedom of movement in that compartment which is the region where exchange with elements contained in the fetal vascular tree takes place.