Reduction Of Twins Research Articles

On the difference of the enhanced power graph and the power graph of a finite group

The difference graph D(G) of a finite group G is the difference of the enhanced power graph of G and the power graph of G, where all isolated vertices are removed. In this paper we study the connectedness and perfectness of D(G) with respect to various properties of the underlying group G. We also find several connections between the difference graph of G and the Gruenberg-Kegel graph of G. We also examine the operation of twin reduction on graphs, a technique which produces smaller graphs which may be easier to analyze. Applying this technique to simple groups can have a number of outcomes, not fully understood, but including some graphs with large girth.

Twin management in the mare: A review.

Twin gestation in the mare is undesirable and can have disastrous consequences. As in many cases, the key to success in twin management lies in a thorough follow-up and accurate recording of clinical findings in the pre-breeding examination. A pregnancy diagnosis in the mobility phase is imperative for a good outcome in the event of twin reduction. If a twin gestation is not diagnosed during this early pregnancy stage, several other procedures exist for managing post-fixation twins (>16 days) with varying degrees of success. Most twin pregnancies are the result of multiple ovulations (dizygotic twins). However, monozygotic twins are also sporadically diagnosed, due to the increasing number of transferred in vitro produced equine embryos. In these cases, the most optimal treatment strategy still needs to be determined. This review provides an overview of the various twin reduction techniques described with the expected prognosis as well as of some less reported techniques with their results. In addition, physiological events and the reduction techniques are demonstrated to the user in virtual 3-dimensional illustrations.

Success rates and factors influencing pregnancy outcome after 464 transvaginal ultrasound-guided twin reductions in the mare.

Transvaginal ultrasound-guided aspiration (TUA) is used for post-fixation twin reduction in mares. However, there is limited information regarding factors that influence pregnancy outcome after TUA. To evaluate the effect of day of gestation on which TUA is performed, aspiration volume, puncture of the conceptus, medication administered before and after TUA, embryo location, mare age and parity and operator experience on pregnancy and foaling rates after TUA. Retrospective case series. Data were collected from case records of 464 TUAs performed by 14 operators in 422 mares diagnosed pregnant with dizygotic twins in two different facilities between 2010 and 2019. Pregnancy status was determined by ultrasonography at 5-7 days and 3-4 weeks after the TUA was performed. Subsequent pregnancy and foaling results were obtained by follow-up communication. The effects of mare, gestation- and TUA-related variables on pregnancy and foaling rates were analysed by the chi-square-test for homogeneity and Fisher's exact test and logistic regression. TUA was performed between 21 and 82 days of gestation in unilaterally (267/359 [74.4%]) and bilaterally fixed (92/359 [25.6%]) twin pregnancies. A singleton pregnancy (218/381 [57.2%]), persistent twin pregnancy (60/381 [15.8%]), or the loss of both conceptuses (103/381 [27%]) was confirmed 5-7 days after TUA was performed. At 3-4 weeks post TUA 50.3% (163/324) of mares were diagnosed with a single viable pregnancy and 40.1% (127/317) went on to deliver a live single foal. TUA performed early in gestation (D 25-35) resulted in the birth of a live singleton foal in 49.3% (74/150) of mares. Missing retrospective data despite extensive follow-up. This is the first large scale study to demonstrate that acceptable pregnancy and foaling rates can be achieved in mares diagnosed with twins when TUA is performed early in gestation (<40 days).

Ultrasound-guided fetal thorax compression to reduce post-fixation twins in the mare.

Management of twin pregnancy after conceptus vesicle fixation in the horse is challenging because the reduction techniques described are either invasive, difficult to perform or associated with disappointing success rates. To evaluate the success of transrectal ultrasound-guided fetal thorax compression for reducing post-fixation twin pregnancy in mares. Retrospective clinical study. Sixteen mares were presented for twin reduction between 51 and 79 days of gestation. History obtained from the owner and/or referring veterinarian detailed information regarding the mare (age, breed), pregnancy (day of gestation, dizygotic versus monozygotic twins, unilateral versus bilateral fixation), treatment and outcome (one live fetus at discharge; live singleton at foaling) after twin reduction. Transrectal fetal thorax compression was performed under ultrasound guidance by two experienced operators. Overall 9 of 16 twin pregnancies were successfully reduced and the likelihood of success was significantly higher in dizygotic than monozygotic twins. The procedure was successful in 9 of 10 dizygotic twins but unsuccessful in all six cases of monozygotic twins. Among the dizygotic twins, two mares lost the pregnancy after discharge from the clinic, seven mares delivered a healthy foal of normal size. Small case number. Transrectal ultrasound-guided fetal thorax compression is a minimally-invasive and successful technique for reducing dizygotic twin pregnancies at approximately 2 months of gestation, but does not lead to any live births in cases of monozygotic twins.

Intertwin nuchal translucency difference predicts the chance of co-twin death after fetal reduction in dichorionic triplet pregnancies: a retrospective analysis study

ObjectivesTo compare the clinical outcomes of different multifetal pregnancy reduction (MFPR) programs in dichorionic (DC) triplets, and explore the association between early ultrasound characteristics and co-twin death after potassium chloride (KCl) injection into one monochorionic (MC) twin.MethodsWe retrospectively reviewed the data of DC triplets who underwent MFPR at our center during 2012–2021. Patients were grouped as follows: intracardiac KCl injection into one MC twin (group A), intracardiac KCl injection into both MC twins simultaneously (group B), and reduction of the singleton fetus (group C) and pregnancy outcomes were compared. Logistic regression was used to determine whether ultrasound measurements at 11–13+6 weeks predicted co-twin death and the receiver operator characteristic (ROC) analysis was conducted to assess the predictive performance.ResultsFinally, we enrolled 184 patients. 153 cases were in group A, and 18, 13 cases were in group B and C respectively. Gestational age at the time of MFPR did not differ among the 3 groups (median: 12^frac67 weeks). The survival rate was 89.6%, 88.9%, and 92.3% in group A, B, and C respectively, which was comparable among groups. Preterm birth was more common in group C (10/12, 83.3%). After KCl injection into one MC twin, co-twin death occurred in 86.3% cases (132/153) within 1 day; however, 3 patients had 2 live births each, with normal postnatal development. Intertwin nuchal translucency (NT) difference/discordance significantly predicted co-twin death within 1 day after MFPR, and the areas under the ROC curve were 0.694 and 0.689, respectively.ConclusionsFor MFPR in DC triplet pregnancies, reduction of the MC twins results in less preterm birth, and women with KCl injection into either one or both MC twins had similar outcomes. Large intertwin NT difference/discordance was associated with co-twin death within 1 day after KCl injection into one of the MC twins.

Noninvasive Evaluation of Fetal Zygosity in Twin Pregnancies Involving a Binary Analysis of Single-Nucleotide Polymorphisms

Twin pregnancy constitutes significant risks for maternal and fetal health, which is usually detected by ultrasound examination at early gestation. However, the imaging-based approach may not accurately identify all twins confounded by practical or clinical variables. The analysis of fetal cell-free DNA in noninvasive prenatal screening assays can completement the ultrasound method for twin detection, which differentiates fraternal or identical twins based on their distinct genotypes. Here, a new noninvasive prenatal screening employing high-coverage next-generation sequencing for targeted nucleotide polymorphisms was developed for detection of zygosity and determination of fetal fraction in twin pregnancies. This method utilizes a binary analysis of both the number and allelic fraction of fetus-specific single-nucleotide polymorphisms to infer the zygosity. In 323 samples collected from 215 singleton, 90 dizygotic, and 18 monozygotic twin pregnancies, all 90 dizygotic twins were correctly detected, with a 100% sensitivity and a 100% specificity. In addition, this method can detect complex pregnancies, such as egg donors, contamination, and twins with complete hydatidiform mole. The fetus-specific fetal fraction change was monitored in nine dizygotic twin pregnancies, which demonstrated highly variable dynamics of fetal cell-free DNA turnover up to 7 weeks after twin reduction. Overall, this study provides a new noninvasive prenatal screening strategy for the accurate identification of twin zygosity and quantification of fetal fraction, which has important clinical implications for the management of twin pregnancies.

Laplacian spectra of cographs: A twin reduction perspective

A graph is a cograph if and only if it has no induced path on 4 vertices. The twin reduction graph of a graph G is denoted by RG. In this article, we describe the Laplacian eigenvalues and eigenvectors of a cograph G using its twin reduction graph RG, and characterize cographs with even and odd integer eigenvalues, respectively. We provide a construction for the Laplacian cospectral cographs. Further, we provide a complete description of the Laplacian spectrum of H-join of graphs when H is a cograph, and then obtain bounds for the algebraic connectivity of such graphs. We also provide some interesting observations on Hadamard diagonalizable cographs.

Pregnancy Outcome After Selective Fetal Reduction in Dichorionic Twin Pregnancies.

This study was conducted for determining pregnancy outcome after selective fetal reduction in twin pregnancies based on the gestational age at the time of the procedure in a referral academic center between 2017 and 2021. This retrospective cohort study included all women with twin pregnancies who were diagnosed with a genetic or structural anomaly of one fetus or a desire to reduce the number of fetuses in order to reduce pregnancy complications visited in the period of 2017-2021. Reduction was performed due to an abdominal approach at 11 to 23 weeks of pregnancy. Maternal and pregnancy information were recorded. A total of 159 cases of twin dichorionic pregnancies were included. The highest frequency of reduction was performed at the gestational age of 18-20 weeks, and the most common cause of reduction was major structural anomalies in the fetus. The results showed the average gestational age (GA) at the time of delivery to be 37.6 weeks, the average birth weight of 2,999 grams, the incidence of miscarriage (loss before 22 weeks) to be 9.4% and a rate of preterm birth (delivery before 37weeks) of 33.3%. There is not a statistically significant relationship between the gestational age at the time of reduction and preterm birth, the birth weight, the incidence of RDS and the incidence of SGA. Fetal reduction of twins to singleton pregnancy is associated with lower risk of preterm birth (delivery before37 weeks reduction of twins to singleton pregnancy is associated with lower risk of preterm birth (delivery before37 weeks). It causes an increase in birth weight and perinatal outcome in remaining co-twin so we recommend fetal reduction after counselling with patients for their unique situation to improve pregnancy outcome.

Sexing of Embryos at the Time of Twin Reduction: A Clinical Approach.

This study provides new unique information on bovine twin pairs during the late embryonic period (28-34 days of pregnancy) in relation to (1) a predictive ultrasound measurement that was differential for sexing heterosexual twins; (2) intrauterine embryonic growth patterns in twin pairs; and (3) a higher vulnerability of female embryos compared to males following an induced embryo reduction in heterosexual twins. The study population comprised 92 dairy cows carrying bilateral twins. A length difference between co-twins equal to or greater than 25% in around 50% of pregnancies served to determine the sex of embryos with 100% accuracy in heterosexual twins, which was assessed four weeks later on the remaining fetus after twin reduction. The apparent rates of growth of twin pairs and of individual male and female embryos from day 28 to 34 of gestation were similar to established growth pattern standards for singletons. Mean embryo sizes in relation to gestational age were smaller by some 5 days' growth equivalent in twins compared to singletons. After the reduction in the female embryo in heterosexual twins, the risk of male embryo loss was null. This new information allowed for sex selection at the time of twin reduction.

Outcomes of Elective Compared to Non-Elective Fetal Reduction by Radiofrequency Ablation in Monochorionic Multifetal Pregnancies

Introduction: Higher order fetal gestation is associated with adverse pregnancy outcomes, and monochorionic (MC) pregnancies have unique complications. Multifetal pregnancy reduction (MPR) by radiofrequency ablation (RFA) may be used to optimize the outcomes of a single fetus. The purpose of this study was to determine whether pregnancy outcomes differ for elective reduction compared to reduction for medically complicated MC multifetal pregnancies. Methods: This was a retrospective cohort of patients with MC twins and higher order multiples who underwent MPR via RFA at a single institution between 2008 and 2021. Patients undergoing elective reduction were compared to patients undergoing reduction due to a complication of MC pregnancy. Pregnancy outcomes were evaluated. Results: Forty-eight patients who underwent RFA reduction between 2008 and 2021 were included in the analysis. Sixteen patients (33.3%) underwent elective RFA for MPR, and 32 (66.7%) underwent an RFA procedure for a complicated pregnancy. All pregnancies with RFA performed for elective indication had a continuing pregnancy (live birth rate 100%). There were no reported pregnancy losses within 4 weeks of the procedure when performed for a solely elective indication (n = 0) compared to 6.3% of complicated multifetal pregnancy (n = 2; 6.3%) (p = 0.001). Conclusion: In this retrospective cohort study, elective reduction of MC twins using RFA was associated with no cases of fetal loss or PPROM within 4 weeks of the procedure and a 100% live birth rate.

Pathophysiology, diagnosis, and management of twin anemia polycythemia sequence in monochorionic multiple gestations.

Twin anemia polycythemia sequence (TAPS) is a consequence of unequal sharing of red blood cells between monochorionic twins resulting in anemia in the donor and polycythemia in the recipient twin. Prenatally TAPS can occur spontaneously or complicate incomplete laser surgery for twin transfusion syndrome. While there may be clinical overlap with twin transfusion syndrome or selective fetal growth restriction, diagnosis relies on Doppler measurement of middle cerebral artery peak systolic velocities. Significantly discordant velocities are diagnostic, while severity staging is based on signs of cardiovascular compromise. Conservative management, fetoscopic laser coagulation, selective twin reduction, fetal blood and exchange transfusion, and delivery may be selected guided by the gestational age of diagnosis, the severity of the condition, the likelihood of success, and the patients' priorities. Prenatal curative treatment that minimizes the risk for prematurity and residual morbidity at birth is most likely to offer the greatest short-term and long-term benefits.

Twin reduction in the late embryonic period prevents the condition of freemartin in dairy cattle.

The condition of freemartinism occurs in the bovine heterosexual twin foetuses and refers to the resulting infertile female. Vascular anastomoses of the foetal membranes are the major reason of this anomaly. This study examines whether single born heifers following induced twin reduction at 28-34 days of pregnancy could develop normal reproductive functions. The study population derived from 367 lactating dairy cows carrying: unilateral twins (n=178), bilateral twins (n=174) or triplets (n=15), in which manual embryo reduction was performed. The final study population was constituted of 95 single born twin females that reached 12months of life and entered into the AI period. Of these heifers, 40 have had one unilateral co-twin, 49 one bilateral co-twin, and 6 two contralateral co-twins. A total of 1688 heifers inseminated during the same period were used as controls to compare the rates of pregnancy at 15months of age, culling due to infertility and birth before the age of 24months. No differences were detected between groups. With an accepted incidence rate of 50% heterosexuality for all twin sets, we should assume that half of our study population had a male co-twin. Our results indicate lack of effect of the male co-twin on normal development of the gonads and genital tract of his female partner during the late embryonic period.

Management of monozygotic twins in the mare

In the horse, only a small number of monozygotic twins and triplets have been reported and commonly, the outcome is poor. As in man, an association between the occurrence of monozygotic twins and the use of assisted reproductive technologies (ART) has been suggested. In the mare, transfer of in vitro produced (IVP) embryos appears to increase the incidence of monozygotic twinning (1.6%; 4/254) compared to transfer of in vivo embryos (0%; 0/413) (Dijkstra et al. Equine Vet J. 2020; 52: 258-261). Due to the type of placental arrangement, these monozygotic twin pregnancies are difficult to reduce to a singleton using reduction techniques commonly applied to dizygotic twins. In this report, 8 cases of monozygotic twins are presented, all of which resulted from transfer of a single IVP embryo. Seven were presumed to be monochorionic diamniotic/diallantoic and one dichorionic diamniotic/diallantoic, based on membrane classification by ultrasound and/or post-expulsion examination. Similar to previously described cases, twin pregnancy only became apparent at 25 days of gestation, when two embryos with heartbeat were visualized. Depending on gestational stage, different twin reduction techniques were applied. In one case, only referred at day 40 of gestation andclassified as dichorionic diamniotic/diallantoic, a transvaginal ultrasound guided aspiration (TUGA) was performed. Reduction of two other twins was performed by per rectum compression of the fetal thorax at day 65 of gestation. In two other cases, cranio-cervical dislocation was performed at day 75-80 of gestation. Finally, transcutaneous ultrasound guided twin reduction was attempted at day 120 of gestation in one case. However, only one of the 6 treated monozygotic twins was successfully reduced, resulting in a live foal born following thorax compression at 65 days of gestation; all other cases resulted in death of both fetuses. In addition, two remaining cases (2/8) lost their pregnancy spontaneously at around 42 days and 8 months of gestation, whereby in the latter the presence of twins was not established at previous ultrasound examinations. Based on these limited cases, only one monozygotic twin was successfully reduced, using the thoracic compression method at day 65 of gestation. These results highlight the need for further investigation into the best reduction method, depending on the gestational stage and on how much the demise of one fetus affects the survival of its co- twin, which may depend on placental arrangement.

Correlation analysis of adverse outcomes for the selective reduction of twin pregnancies

BackgroundDue to the extensive development of assisted reproductive technology, the number of twin pregnancies has increased significantly over recent decades. Twin pregnancy is the most representative type of multiple pregnancies and is associated with high infant morbidity and mortality. Perinatal complications of twin pregnancy are also markedly increased compared with those of single pregnancy. Transabdominal selective reduction (SR) is a remedial intervention. This study aimed to research the adverse outcomes of transabdominal selective reduction of twin pregnancy and the correlation between the reduction week and pregnancy outcomes.ObjectiveThe purpose of this study was to examine the adverse outcomes of the transabdominal selective reduction of twin pregnancy and the correlation between the reduction week and pregnancy outcomes.MethodsA retrospective cohort study of the transabdominal reduction of twin pregnancy was conducted in a single prenatal diagnosis medical centre from September 2012 to October 2020. According to chorionicity, women with twin pregnancies were divided into 2 groups: dichorionic (DC) twin pregnancies and monochorionic (MC) twin pregnancies. Women with DC twin pregnancies underwent potassium chloride reduction, and those with MC twin pregnancies underwent radiofrequency ablation (RFA). The reduction indications included pregnancy complications, foetal abnormalities, and maternal factors. The perinatal outcomes of different chorionic twins after reduction were analysed. Each foetus with an adverse outcome was included. The relative relationship between the reduction weeks and delivery weeks of twins was examined by correlation analysis.ResultsA total of 161 women were included in this study. A total of 112 women had DC twin pregnancies, and 49 women had MC twin pregnancies. Preterm delivery rates were significantly higher in the MC twin reduction group than in the DC twin reduction group prior to 37 weeks (53.1% vs. 29.5%, P = 0.004). The mean gestational age at delivery of the foetuses in the DC twin group that underwent SR was significantly older than that of those in the MC twin group that underwent SR (36.9 ± 4.0 vs. 33.5 ± 6.6 weeks, P = 0.001). The number of DC twins that underwent SR and were delivered after 37 weeks was obviously greater than that of the MC twins that underwent SR (70.5% vs. 46.9%, P = 0.004). The foetal survival rate was 95.5% in the DC twin reduction group and 77.6% in the MC twin reduction group. If the indication of TTTS was not included, there was no significant difference in the foetal survival rate of the DC and MC twin reduction groups (95.5% vs. 86.2%, P = 0.160). Cotwin death 1 week after reduction was greater in the MC group (6.1% vs. 0%, P = 0.027). Compared to other indications, this finding indicated that a significantly lower proportion of women remained undelivered after selective reduction with the indication of TTTS. There was a significant negative correlation between the reduction weeks and delivery weeks of the two groups (P < 0.01), and the best opportunity for reduction was before 22 weeks of gestation.ConclusionThese findings highlighted an obviously negative correlation between the reduction week and delivery week. The transabdominal selective reduction of twin pregnancy should be considered for a lower rate of miscarriage or premature delivery if the reduction week takes place earlier in pregnancy. The rate of preterm delivery was the lowest when transabdominal selective reduction was completed before 22 weeks of gestation. Compared with other RFA indications, a higher rate of premature delivery was shown for MC twins with a reduction indication of TTTS. TTTS with sIUGR might be one of the reasons for the adverse outcomes of reduction for MC twin pregnancy.

The clinical outcomes of selective and spontaneous fetal reduction of twins to a singleton pregnancy in the first trimester: a retrospective study of 10\xa0years

BackgroundSingleton pregnancy is encouraged to reduce pregnancy complications. In addition to single embryo transfer (SET), selective and spontaneous fetal reduction (SEFR and SPFR) can also achieve singleton pregnancies. After SEFR or SPFR, an inanimate fetus remains in the uterus. It is unclear whether the inanimate fetus would adversely affect another fetus or the mother. Previous studies have focused on the differences between pre- and post-reduction. However, studies focusing on the influence of SEFR and SPFR on the remaining fetal development and maintenance of pregnancy are rare.MethodsMaterials from 5922 patients whose embryo transfer dates ranged from March 2011 to January 2021 were collected. Both the SEFR group (n = 390) and SPFR group (n = 865) had double embryos transferred (DET) and got twin pregnancies, but subsequent selective or spontaneous fetal reduction occurred. The SET group (n = 4667) had only one embryo transferred. All were singleton pregnancies on the 65th day after embryo transfer. Clinical outcomes, including pregnancy outcomes, pregnancy complications, and newborn outcomes, were compared among the three groups.ResultsAfter adjusting for age, infertility duration, types of infertility, states of embryos, body mass index, and factors affecting SET or DET decisions, multivariate regression analysis revealed that SEFR increased the risk of miscarriage (OR 2.368, 95% CI 1.423–3.939) and preterm birth (OR 1.515, 95% CI 1.114–2.060), and reduced the gestational age (βeta -0.342, 95% CI -0.544– -0.140). SPFR increased the risk of gestational diabetes mellitus (GDM) (OR 1.657, 95% CI 1.215–2.261), preterm premature rupture of membranes (PPROM) (OR 1.649, 95% CI 1.057–2.574), and abnormal amniotic fluid volume (OR 1.687, 95% CI 1.075–2.648). Both SEFR and SPFR were associated with reduced live birth rate (OR 0.522, 95% CI 0.330–0.825; OR 0.671, 95% CI 0.459–0.981), newborn birth weight (βeta -177.412, 95% CI -235.115–-119.709; βeta -42.165, 95% CI -83.104–-1.226) as well as an increased risk of low-birth-weight newborns (OR 2.222, 95% CI 1.490–3.313; OR 1.510, 95% CI 1.092–2.087).ConclusionsDET with subsequent fetal reduction was related to poor clinical outcomes. We recommend that DET with subsequent fetal reduction should only be considered as a rescue method for multiple pregnancy patients with potential complications, and SET is more advisable.

Fetal reduction from twin to singleton gestation: A meta-analysis.

To evaluate outcomes of fetal reduction in twin pregnancy. PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and Google Scholar were searched from 1980 through December 2020. Prospective or retrospective studies of pregnant women with twin gestations who had a transabdominal reduction of twin to singleton pregnancy with a comparison group of ongoing twin gestations. Outcomes were meta-analyzed only if reported in at least three studies. Six studies with a pooled sample of 2867 women with a twin pregnancy of whom 624 underwent 2-to-1 reduction and 2243 did not. In the fetal reduction group, the odds of preterm birth before 34 and 37weeks of pregnancy were lower by 36% (odds ratio [OR] 0.64, 95% confidence interval [CI] 0.48-0.86, P<0.003) and 77% (OR 0.23, 95% CI 0.12-0.44, P<0.001), respectively, than in the control group, and the odds of hypertensive disorders and cesarean delivery were lower by 75% (OR 0.25, 95% CI 0.15-0.43, P<0.001) and 65% (OR 0.35, 95% CI 0.20-0.62, P<0.001), respectively. Twin reduction to singleton pregnancy decreased the possibility of preterm birth, hypertensive disorders in pregnancy and cesarean delivery. Sufficiently powered prospective studies are needed to support these findings.

Radiofrequency Ablation of Umbilical Cord for Reduction of Twin Reversed Arterial Perfusion Sequence: A Case Series

Objective: To evaluate the outcome of radiofrequency ablation of the umbilical cord in the reduction of Twin Reversed Arterial Perfusion (TRAP) sequence or acardiac twin in monochorionic diamniotic pregnancies. Material and methods: In this prospective study, 25 cases of monochorionic diamniotic pregnancy with one acardiac twin underwent selected reduction using radiofrequency ablation (RFA) in the second trimester of gestational age, from 2018 to 2019 in a tertiary referral hospital affiliated to Tehran University of Medical Sciences. Results: The overall survival rate was 84%. The mean±SD of gestational age at the time of the procedure and delivery were 20.0±3.8 and 35w±6.0 days respectively. Nine neonates were admitted to the neonatal intensive care unit (NICU) and 4 miscarriages were recorded in less than 24 weeks. The procedures in all cases were technically successful in achieving selective termination. Conclusion: Radiofrequency ablation for fetal reduction in acardiac twins in monochorionic pregnancies appears to be a safe and reasonable option.

Elective fetal reduction by radiofrequency ablation in monochorionic diamniotic twins decreases adverse outcomes compared to ongoing monochorionic diamniotic twins

Multifetal pregnancy reduction is a technique used to reduce the fetal number to mitigate the risks of adverse outcomes associated with multiple gestations. Monochorionic diamniotic twin pregnancies are subject to unique complications, contributing to adverse pregnancy outcomes. Thus, patients have an option to electively reduce 1 fetus to improve outcomes. This study aimed to compare outcomes of elective reduction of monochorionic diamniotic twins by radiofrequency ablation to planned ongoing monochorionic diamniotic twins. We performed a retrospective review of 315 monochorionic diamniotic twin gestations that underwent first-trimester ultrasound within 1 institution. Planned electively reduced twins were compared with ongoing monochorionic diamniotic twins. All reductions were performed via radiofrequency ablation of the cord insertion site into the fetal abdomen. The primary outcome was preterm birth at <36 weeks' gestation. Secondary outcomes included gestational age at delivery; preterm birth at less than 37-, 34-, 32-, and 28-weeks' gestation; unintended loss; and adverse perinatal outcomes. Among 315 monochorionic diamniotic pregnancies, 14 (4.4%) underwent elective multifetal pregnancy reduction, and 301 (95.6%) were planned ongoing twins. The mean gestational age of radiofrequency ablation in the elective multifetal pregnancy reduction group was 15.1±0.68 weeks. Patients who underwent elective multifetal pregnancy reduction had significantly higher maternal age (P<.01) and were more likely to be Asian (P<.01). Moreover, they were more likely to have undergone in vitro fertilization (P=.03) and chorionic villus sampling (P<.01). There was a significantly higher rate of term deliveries in the elective radiofrequency ablation group compared with ongoing twins (gestational age, 38 weeks [interquartile range, 36.1-39.1] vs 35.9 weeks [interquartile range, 34.0-36.9]; P<.01). Patients with ongoing pregnancies had a trend of increased rate of preterm birth at <36 weeks' gestation (odds ratio, 3.4; 95% confidence interval, 1.0-12.0; P=.06), a significantly increased risk of preterm birth at <37 weeks' gestation (odds ratio, 8.0; 95% confidence interval, 2.4-26.4; P<.01), and no difference at less than 34-, 32-, or 28- weeks' gestation. All patients who underwent elective radiofrequency ablation had successful pregnancies with no pregnancy losses or terminations. Of ongoing gestations, 36 required procedures, including 16 (5.3%) medically indicated radiofrequency ablation, 14 (4.6%) laser ablation, and 6 (1.9%) amnioreductions. Furthermore, 22 patients (7.3%) with planned ongoing twins had total pregnancy loss at <24 weeks' gestation. Notably, 12 patients (4.0%) had unintended loss of 1 fetus before 24 weeks' gestation in the ongoing pregnancy cohort, and 12 patients (4.0%) had unintended loss of both fetuses before 24 weeks' gestation. Moreover, 5 patients (1.7%) in the ongoing pregnancy group had intrauterine fetal demise at >24 weeks' gestation and 10 patients (3.3%) electively terminated both fetuses. There was no significant difference in loss rates between the 2 groups. In this study of monochorionic diamniotic twins, patients who elected to undergo multifetal pregnancy reduction had significantly lower rates of preterm birth at <37 weeks and a lower trend of preterm birth at <36 weeks' gestation without an increased risk of pregnancy loss. Median gestational age at delivery was significantly higher in the elective multifetal pregnancy reduction group (38 weeks) than in the ongoing pregnancy group (35.9 weeks). Further research is needed to clarify if multifetal pregnancy reduction improves long-term outcomes.

Microstructural Evolutions under Ultrasonic Treatment in 304 and 316 Austenitic Stainless Steels: Impact of Stacking Fault Energy

Herein, the influence of ultrasonic treatment (UST) on the microstructure of AISI‐304 and AISI‐316 stainless steels as two common commercial grades with similar properties but different levels of stacking fault energy (SFE) is compared. The softening effect of the ultrasonic wave on the predeformed structure is demonstrated by microhardness measurements, and the relaxation of tensile residual stresses is affirmed through the X‐ray diffraction (XRD) peak shifting. Electron and optical microscopy reveals a significant impact of ultrasound on the reduction of the deformation twins’ fraction. A new mechanism for detwinning under the action of ultrasonic vibration is proposed using electron backscatter diffraction (EBSD) analysis. Reductions of 25% and 34% are detected in dislocation density of the 10% predeformed tensile sample after 300 W UST for the 304SS and 316SS alloys, respectively. The effect of the SFE is discussed, and it turns out that cross‐slip is the main mechanism of dislocation annihilation as a result of UST. Observation of the low‐deformation regions close to the grain boundaries indicates the occurrence of the recrystallization phenomenon during UST. Dislocation annihilation, detwinning, dislocation absorption to grain boundaries, and recrystallization are regarded as the softening and relaxation mechanisms of UST for austenitic stainless steels.

Radiofrequency ablation for selective fetal reduction in complicated Monochorionic twins; comparing the outcomes according to the indications

BackgroundTo evaluate the perinatal outcomes in women with complicated monochorionic diamniotic twins who underwent selective reduction using radiofrequency ablation (RFA).MethodsThis retrospective study included patients with complicated monochorionic diamniotic twins between 16 to 28 weeks who underwent selective reduction using RFA.ResultsDuring the study period, 143 women with complicated monochorionic twins underwent RFA including 52 with selective fetal growth restriction (sFGR), 48 with twin to twin transfusion syndrome (TTTS), 33 with major fetal anomalies in one of the twins, and 10 with reversed arterial perfusion sequence (TRAP). The overall survival was 71.3% (102/143). The procedures were technically successful in achieving selective termination in all cases. The mean ± SD of gestational age at the time of the procedure was 21.0 ± 2.3 weeks. The mean ± SD of gestational age at delivery was 34.6 ± 3.3 weeks. The mean ± SD of overall procedure-to-delivery time was 12 ± 1.7 weeks. The pregnancy success rates among sFGR, TRAP, TTTS and anomaly groups were 82.7, 80, 73 and 60.7% respectively. There were no maternal complications.ConclusionRadiofrequency ablation for fetal reduction in complicated monochorionic twin pregnancies appears to be a reasonable option. The pregnancy success rate following RFA selective reduction was highest among sFGR and TRAP groups and lowest in the anomaly group.