Monochorionic Pairs Research Articles

Highlights from the International Twins Congress 2021

Highlights from the International Twins Congress 2021

EP21.03: Outcomes of intrafetal ablation in a monochorionic pair of a multifetal pregnancy at 11–14 weeks: a single referral centre experience

EP21.03: Outcomes of intrafetal ablation in a monochorionic pair of a multifetal pregnancy at 11–14 weeks: a single referral centre experience

Pregnancy and obstetric outcomes of dichorionic and trichorionic triamniotic triplet pregnancy with multifetal pregnancy reduction: a retrospective analysis study

BackgroundIt is generally beneficial for triplet gestation or high-order multiple pregnancies to operate multifetal pregnancy reduction (MFPR) after assisted reproductive techniques. However, data on pregnancy outcomes is lacking regarding dichorionic triamniotic (DCTA) and trichorionic triplets (TCTA) pregnancy.MethodThis research analyzes the difference between 128 DCTA and 179 TCTA pregnancies with or without MFPR after in vitro fertilization/intracytoplasmic sperm injection cycles between January 2015 and June 2020. The subdivided subgroups of the two groups are reduction to singleton, reduction to dichorionic twins, and expectant management groups. We also compare the pregnancy and obstetric outcomes between 2104 dichorionic twins and 122 monochorionic twins.ResultThe research subgroups were DCTA to monochorionic singleton pregnancies (n = 76), DCTA to dichorionic twin pregnancies (n = 18), DCTA-expectant management (n = 34), TCTA to monochorionic singleton pregnancies (n = 31), TCTA to dichorionic twin pregnancies (n = 130), and TCTA-expectant management (n = 18). In DCTA-expectant management group, the complete miscarriage rate is dramatically higher, and the survival rate and the rate of take-home babies are lower. However, there was no difference between the rates of complete miscarriages, survival rates, and take-home babies in TCTA-expectant management group. But the complete miscarriage rate of DCTA-expectant management was obviously higher than that of TCTA-expectant management group (29.41 vs. 5.56%, p = 0.044). For obstetric outcomes, MFPR to singleton group had higher gestational week and average birth weight, but lower premature delivery, gestational hypertension rates and low birth weight in both DCTA and TCTA pregnancy groups (all p < 0.05). DCTA to monochorionic singleton had the lowest incidence of gestational diabetes, whereas The subdivided subgroups of TCTA had no significant difference in the incidence of gestational diabetes. Monochorionic twins have higher rates of complete, early, and late miscarriage, premature delivery, and late premature delivery, and lower survival rate (p < 0.05).ConclusionMFPR could improve gestational week and average birth weight, reducing premature delivery, LBW, and gestational hypertension rates in DCTA and TCTA pregnancies. Monochorionic twins have worse pregnancy and obstetric outcomes. MFPR to singleton is preferable recommended in the pregnancy and obstetric management of complex triplets with monochorionic pair.

Outcome of radiofrequency ablation for selective fetal reduction before vs at or after 16 gestational weeks in complicated monochorionic pregnancy

To investigate whether gestational age at intervention (< or ≥ 16 weeks) and other factors affect the risk of loss of the cotwin after selective fetal reduction using radiofrequency ablation (RFA) in monochorionic (MC) pregnancy. This was a single-center retrospective analysis of 63 consecutive RFA procedures performed at our institution from January 2011 to October 2019 for selective fetal reduction in complicated MC pregnancies. Indications for RFA were twin reversed arterial perfusion sequence (13 cases), twin-to-twin transfusion syndrome (12 cases), twin anemia-polycythemia sequence (two cases), selective fetal growth restriction (10 cases), discordant anomalies (17 cases) and multifetal pregnancy reduction in triplets or quadruplets with a MC pair (nine cases). Twenty-six (41.3%) of these procedures were performed before and 37 (58.7%) after 16 weeks. Potential factors that could affect the risk of loss of the cotwin, including gestational age at RFA, order of multiple pregnancy, amnionicity, indication for RFA and number of ablation cycles, were assessed first by univariate analysis and then by multivariate analysis. There were 17 (27.0%) cotwin losses. Ablation cycles numbering four or more was the only factor among those investigated to be associated with loss of the cotwin after RFA (P = 0.035; odds ratio, 5.21), while the indication for RFA, order of multiple pregnancy, amnionicity and gestational age at RFA had no effect. Comparing RFA performed at < 16 vs ≥ 16 weeks, there was no difference in the rate of cotwin loss (23.1% vs 29.7%; P = 0.558) or preterm prelabor rupture of the membranes before 34 weeks (7.7% vs 5.4%; P = 0.853), or in the median gestational age at delivery (36.2 vs 37.3 weeks; P = 0.706). RFA is a promising tool for early selective fetal reduction in MC pregnancy before 16 weeks. Four or more ablation cycles is a major risk factor for cotwin loss. Careful assessment pre- and post-RFA, together with proficient operative skills to minimize the number of ablation cycles, are the mainstay to ensure that this procedure is effective and safe. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

COMPARATIVE ANALYSIS OF THE NEONATE BIRTH WEIGHT IN DIFFERENT TYPES OF TIN PREGNANCY

The relevance of the study lies in the significant increase in multiple pregnancies connected with the higher risk of perinatal complications, the controversy over the effects of chorionicity and sex of the babies on their birth weight, the need for timely diagnosis of fetal growth restriction, and associated morbidity.&#x0D; The objective of this study was to compare fetal weights at the birth of different variants of twins depending on chorionicity, gestational age, and sex.&#x0D; Materials and methods. During 2016-2020, 440 pairs of twins were examined: 375 dichorionic diamniotic and 65 monochorionic diamniotic (38 – boys, 27 – girls). Among dichorionic couples there were 186 (49.6%) opposite-sex, 98 (26.1%) same-sex males and 91 (24.3%) same-sex females. Fetal weight was measured at birth, and its relationship to chorionicity, fetal sex, a combination of same-sex or opposite-sex co-twins, and gestational age was assessed.&#x0D; Results. The average weight of 750 fetuses from dichorionic pairs (2570.0 ± 506.43 g) significantly exceeded the weight of 130 fetuses from monochorionic pairs (2333.4 ± 567.24 g, p &lt; 0.0001). The same-sex male (2603.8 ± 532.29 g) and opposite-sex dichorionic diamniotic (2595.6 ± 490.17 g). twins’ masses significantly surpassed the mass of all other twins (p &lt;0.05). In the group of dichorionic twins, the weight of boys exceeded the weight of girls (2638.1 ± 525.96 g vs. 2499.4 ± 475.84 g, p = 0.0002). This pattern was observed both inside the opposite-sex pairs (2674.2 ± 518.17 g vs. 2517.1 ± 448.24 g, p = 0.0019), and same-sex couples of boys compared to same-sex couples of girls (2603.8 ± 532.29 g and 2481.4 ± 503.08 g, respectively, p = 0.0224). No significant difference in the weight of girls of opposite-sex twins compared to same-sex couples was seen. In monochorionic pairs, the weight of male and female fetuses did not differ significantly. Birth weight discordance was found in all types of twins, the highest percentage of discordance was registered in monochorionic boys – 23.7%, second place in frequency took male dichorionic twins – 20.4%. Among the 30 discordant dichorionic opposite-sex twins in 19 (63.3%) cases, the male fetus was heavier. There was no significant difference in fetal weight when women were fertilized naturally and using assisted reproductive technologies. The average weight of children born by surrogate mothers exceeded the weight of children born by non-surrogate mothers (p = 0.0466). In the first pregnancy, children were born with a lower body weight compared to children born as a result of repeated pregnancies and in women who had a history of childbirth.&#x0D; Conclusion. The average weight of the fetuses of dichorionic twins was higher than the weight of the neonates f monochorionic pairs. The prevalence of the weight of boys over the weight of girls from dichorionic pairs and the absence of sex difference in fetal weight in monochorionic twins indicates the possibility of different functional activity of the placenta in fetuses of different sexes. Small for gestational age newborns were most often found in the group of female monochorionic twins and opposite-sex dichorionic pairs. Discordance of fetal mass was most common in monochorionic same-sex male twins. In discordant opposite-sex couples, the male fetus more often was heavier. There was no significant difference in newborn weight when women were fertilized naturally and with the use of assisted reproductive technologies. The average weight of surrogate-born children exceeded the weight of children born by non-surrogate mothers. In the first pregnancy, children were born with a lower body weight compared to children of multiparous and multigravida women.

Repeated triplets complicated by monochorionic diamniotic twins following assisted reproduction: a case report and literature review

BackgroundMonochorionic twinning involves numerous maternal and fetal complications, triplets complicated by a monochorionic pair are at further increased risk. Here, we report a case of repeated triplets complicated by monochorionic diamniotic twins with successful pregnancy outcomes in a woman using autologous oocytes.Case presentationA 30-year-old female undergoing embryo transfer with fresh and frozen embryo cycles with autologous oocytes. The two cycles were confirmed by transvaginal ultrasound to result in successful clinical pregnancies of triplets complicated by a monochorionic twinning. The first pregnancy resulted in a singleton delivery after a selective reduction of the monochorionic pair. The subsequent pregnancy resulted in a dichorionic diamniotic twin pregnancy after the heartbeat of one of the monochorionic twin fetuses stopped at 43 days after embryo transfer. Both of the pregnancies ended with successful live births.ConclusionsOur case report of repeated triplets with monochorionic twins suggests the potential causes and risk factors of monochorionic twinning in assisted reproduction and raises concern regarding the timing of multifetal pregnancy reduction.

Cardiac Anomalies in Liveborn and Stillborn Monochorionic Twins.

Cardiovascular anomalies are more common in monochorionic twins, especially with twin-twin transfusion, compared to other twin types and to singletons. Because previous studies are based on fetal and neonatal echocardiography, more information is needed to study prevalence of cardiac anomalies in twin miscarriages, stillbirths, and children after the immediate neonatal period. With specific attention to cardiac anomalies, we reviewed the medical records of 335 selected liveborn twin pairs from the Marshfield Clinic Twin Cohort (enriched for twin-twin transfusion) and all twins (175 pairs) identified in the Wisconsin Stillbirth Service Program cohort of late miscarriages and stillbirths. Structural cardiac defects occurred in 12% of liveborn monochorionic twin infants and 7.5% of stillborn infants with twin-twin transfusion compared to only 2% of liveborn dizygotic twins and no stillborn dizygotic infants. The most common cardiac lesion in liveborn twins was ventricular septal defect, which was usually isolated and discordant, preferentially affecting the smaller twin in monochorionic pairs. Among stillborn and miscarried monochorionic twins, the most common cardiac lesion was acardia. Monochorionic twins, particularly those with TTT, are at increased risk for a spectrum of structural cardiac malformations which we suggest may be related to asymmetry of the inner cell mass resulting in a smaller poorly perfused twin. In severe cases, limited cardiac and circulatory development in the affected twin leads to acardia. In less severe cases, the smaller infant has deficient septal growth that sometimes results in ventricular septal defect.

Early demise of twins in a cohort of stillbirths and second trimester miscarriages.

Twins, particularly monochorionic (MC) pairs, are at increased risk for fetal death. Whereas previous work has sought to understand the mechanisms for this increased mortality, most studies analyze viable twin pregnancies or liveborn twin cohorts. In the Wisconsin Stillbirth Service Program cohort of 3,137 stillbirths and second trimester miscarriages, we identified 175 twin pregnancies for a twinning rate of 56/1,000, which is approximately double the general population. The excess of twins among miscarriages and stillbirths was attributable to MC pairs as the incidence of dizygotic (DZ) twinning was not increased compared to livebirth data. The leading causes of fetal demise among twins were twin-twin transfusion, acardia, and twin-twin disruption. Maternal causes of death, primarily premature rupture of membranes, were moderately increased in both MC and DZ twins relative to singletons. Although deceased twins were smaller than expected for viable twins at comparable gestational ages, placenta weights of deceased MC pairs were large compared to combined fetal weight, which indicates placental inefficiency likely due to vascular shunting. Co-twin survival was much lower for MC than for DZ pairs. Therefore, earlier diagnosis and treatment of MC twinning complications may decrease prenatal mortality.

Our results of spontaneously conceived triplet pregnancies

The natural incidence of spontaneous triplet pregnancy is approximately 1 in 8000 births. Premature delivery of one fetus, compromise of one fetus, and death of one fetus of a multiple gestation with healthy co-fetuses are complications unique to multiple gestations. Our purpose was to evaluate the outcome of spontaneous triplet gestations. In this retrospective study, maternal, neonatal data were collected from 25 sets of triplet pregnancies that were diagnosed between 2011 March and December 2013 in Zekai Tahir Burak WomenÂ’s Health Education and Research Hospital - Obstetric Department. There were 15 sets of trichorionic triamniotic triplet pregnancies and 10 sets of triplet pregnancies with a monochorionic pair (ie, dichorionic triamniotic triplets). The mean maternal age was 28 (20-33). 75% of patients were primigravida. 50% of patients (12 patient) had abortus (gave birth before 20 weeks). 3 patients gave birth about 33 weeks, birth weights were about 2100-2150 grams.4 patients gave birth about 30 weeks ,with birth weigths of 1800-1850 grams. 2 patients had spontaneous abortion of all fetuses after fetal reduction. Two patients (8%) had complication of postoperative endometritis. 3 patients had preeclampsia (12%). The incidence of dichorionicity in our study of spontaneous triplet pregnancy is 40%. Perinatal mortality was increased in dichorionic pregnancies. The abortus rate was 80%. Although abortus rate was high in spontaneous triplet pregnancy,gestational age at delivery was about 33 weeks. This is because of our hospitalÂ’s condition to be a tertiary hospital in obstetrics and neonatology.

OP23.04: Selective reduction in complex triplet pregnancy by radio frequency ablation: single centre experience

The risk of miscarriage and preterm delivery are significantly higher in multiple pregnancies with a monochorionic pair. Intra fetal anastomosis in monochorionic (MC) pair preclude the use of intracardiac potassium chloride and fetal reduction must be performed using cord occlusion techniques such as bipolar cord coagulation, interstitial laser or by radiofrequency ablation. We present our series of selective reduction in complex triplet pregnancy with an MC pair using radiofrequency ablation (RFA). This was a retrospective study of the procedures in our unit for the period between 2010 and 2016. We had 25 cases of complex triplets (19 Dichorionic and 6 Monochorionic triplets). The indications for fetal reduction include 14 of multifetal pregnancy reduction, 9 cases of TTTs in the Monochorionic pair, 1 of fetal anomaly in co twin and 1 of discordant growth in the MC pair. Outcome data was available in 24 cases. Median GA at procedure was 15.4 weeks (range 12.1-21.7) and at delivery was 32.9 weeks (range 17.4-41). We had 3 miscarriages; 2 cases occurred within 2 weeks of procedure. IUD of the co-twin occurred in 3 cases (2 in DCTA and 1 in MCTA). The median GA at delivery following MFPR in complex triplets was 34.6 weeks and in the TTTS group was 32.3 weeks. Complications included complex thermal injury to the co twin in 1 case resulting in the subsequent termination of the co twin. There were no cases of neurological impairment in the survivors post procedure. This is the largest case series of fetal reduction in complex triplets by RFA. Selective reduction by RFA in complex triplet pregnancies resulted in a total pregnancy loss in 12.5% of the cases with an 87.5% favourable outcome, in other words two live babies at discharge from hospital. The gestational age was higher at delivery in the MFPR group compared to other indications for selective fetal reduction. This data is useful in appropriate counselling of complex triplex pregnancies.

Prediction of birth weight discordance from fetal weight estimations at 21–24 weeks' scans in monochorionic and dichorionic twins

Objective: To evaluate if inter-twin estimated fetal weight (EFW) differences at 21–24 weeks’ scans predict birth weight discordance in monochorionic and dichorionic twins born at three gestational age periods.Methods: We counted the number of pairs with discordant EFWs (EFWs greater than the mean + 1SD; i.e. a difference above 12% in dichorionic and 21% in monochorionic twins) derived during a 21–24 weeks’ scan as compared to actual discordant birth weight (>25%) in monochorionic and dichorionic pairs born at ≤32, 33–36 and >36 weeks.Results: We studied 416 dichorionic and 244 monochorionic twins. The frequency of EFWs discordance at 21–24 weeks was the same for dichorionic and monochorionic twins but the total number of birth weight discordant pairs was significantly smaller among dichorionic twins (OR 0.2, 95% CI 0.1, 0.6). Generally, the positive predictive values for birth weight discordance by using the EFWs difference were quite poor, but always better in monochorionic than in dichorionic twins. Whereas the negative predictive value and hence the sensitivity for monochorionic twins was 100% irrespective of gestational age at birth, it was much lower in the dichorionic pairs.Conclusion: Concordant EFWs at 21–24 weeks exclude discordant birth weight in monochorionic twins whereas discordant EFWs are poor predictors of birth weight discordance especially in dichorionic twins irrespective when the twins were born.

Hypertensive disorders during monozygotic and dizygotic twin gestations: A population-based study

ABSTRACTObjective: To determine whether the incidence of hypertensive disorders is different in monozygotic compared to dizygotic twin pregnancies. Methods: A registry-based survey of twin pregnancies delivered during 2003 to 2012. We used the best clinical estimate of zygosity based on the concept that all monochorionic twins are monozygotic and all unlike-sex pairs are dizygotic, thus excluding same-sex dichorionic twin gestations for which zygosity cannot be ascertained on clinical grounds. Study cohorts were twin pregnancies with or without preeclampsia and gestational hypertension. Results: A total of 3419 twin gestations met the inclusion criteria, of which 442 (12.9%) were monochorionic and 1255 (36.7%) were unlike-sex twins, excluding 1722 same-sex dichorionic twin gestations (50.4%). There was no significant difference in the incidence of preeclampsia (OR: 0.9; 95% CI: 0.4–2.0 for monozygotic males and OR: 0.6; 95% CI: 0.3–1.4 for monozygotic females) and gestational hypertension (OR: 0.7; 95% CI: 0.2–2.5 for monozygotic males, and OR: 0.7; 95% CI: 0.2–2.3 for monozygotic females) between monochorionic and unlike-sex pairs. Maternal prepregnancy obesity and nulliparity were the only significant associated factors of preeclampsia (OR: 3.8; 95% CI: 2.0–7.0, and OR: 2.5; 95% CI: 1.4–4.4, respectively). Maternal prepregnancy obesity (OR: 5.5; 95% CI: 2.5–12.2), maternal age ≥36 years (OR: 2.5; 95% CI: 1.1–6.1), and family history of hypertension (OR: 2.6; 95% CI: 1.3–5.1) were significantly associated with gestational hypertension. Conclusion: Based on a large population-based dataset and on the best clinical estimate of twin zygosity, it appears that zygosity is not associated with hypertensive disorders in twin gestations.

Expectant management versus multifetal pregnancy reduction in higher order multiple pregnancies containing a monochorionic pair and a review of the literature.

To compare the perinatal outcome in multifetal pregnancies containing a monochorionic twin pair, managed either expectantly or by fetal reduction (MFPR). This was a retrospective analysis of prospectively collected data on 47 triplet and 10 quadruplet pregnancies recruited between 10 and 14weeks. Main outcome measures were miscarriage <24weeks, preterm birth, fetal growth restriction, birth weight and survival rates. For triplets the miscarriage rates <24weeks were 6.3% after reduction and 20.0% for expectant management and MFPR, respectively. While we recorded no case of severe preterm delivery <30weeks in the reduction group, it was 25% in those with expectant management. Mean gestational age and birth weight were significantly higher after fetal reduction than for the conservative approach (37.7±1.6weeks vs. 30.9±3.2weeks, p<0.01 and 2676±705g vs. 1429±542g, p<0.01). Expectantly managed triplets were complicated by twin-twin transfusion syndrome in 18.8% and intrauterine fetal death in 8.3%. Survival rates were 85.4% for those managed expectantly and 80.0% after fetal reduction. Mean gestational age of ongoing quadruplets was 26.9±2.0weeks vs. 34.5±4.3weeks for those with reduction of the monochorionic pair (p<0.05). Survival rates were 100% in the reduction group and 58.3% in the expectant management group (p<0.05). There was an inverse correlation between the final number of fetuses and the birth weight. Fetal reduction in triplets and quadruplets including a monochorionic pair is associated with decreased early prematurity. While in quadruplets the overall survival is higher after reduction, there was no difference for dichorionic triplets with reduction or conservative management. Complications owing to monochorionicity are frequently observed.

ISUOG Practice Guidelines: role of ultrasound in twin pregnancy.

ISUOG Practice Guidelines: role of ultrasound in twin pregnancy.

Abstract 092: Low Birth Weight per se Is Not a Determinant of Vascular Dysfunction and Presumably Future Cardiovascular Risk in Humans

Background: Epidemiological studies suggest that low birth weight (BW) is associated with systemic vascular dysfunction and premature cardiovascular morbidity and mortality later in life. However, this association could be due to confounding factors associated with low BW, such as genetic factors, pathological events during intrauterine life, and maternal or early-life environmental insults. Studies of monozygotic twins born with significantly different BW provide a unique opportunity to control for these potential confounding factors, thereby allowing to directly study the effect of low BW per se on systemic vascular function later in life. Methods: We, therefore, measured flow-mediated dilation (FMD) of the brachial artery, carotid-femoral pulse wave velocity (PWV) and carotid intima-media thickness (IMT) in 13 monozygotic, monochorionic healthy twins pairs (mean±SD age, 13.5±3.4 years) who were born with significantly different BW (defined as &gt;20% BW difference within pairs, 2310±600 vs. 1800±520 g, P&lt;0.0001) and in 26 healthy age- and sex-matched control subjects born at term with normal BW (3460±360 g). None of the participants had suffered from intrauterine or perinatal complications. Results: The major new findings were two fold; 1) systemic vascular function was comparable in low and high BW twins (FMD, 9.0±1.8 vs. 8.7±2.0%; PWV, 6.5±1.3 vs. 6.6±0.9 m/s; IMT, 390±30 vs. 390±20μm, all P values &gt;0.2, low vs. high BW) and 2) systemic vascular function in twins was similar to the one observed in control singletons (FMD, 8.8±1.3 vs.8.9±1.8%, P=0.95; PWV: 6.5±1.1 vs. 6.6±1.2 m/s, P=0.80; IMT: 390±25 vs. 385±20μm, P=0.33, singletons vs. twins). Finally, there existed no relationship between BW and vascular function in the whole study population (FMD: r=0.001, P=0.99). Conclusions: This study provides the first direct evidence in humans that low BW per se is not a determinant of systemic vascular dysfunction (and presumably future cardiovascular risk). Moreover, it indicates that independent of BW, vascular function in twins is normal. We suggest that the association between low BW and increased cardiovascular risk reported in earlier epidemiological studies was related to confounding factors associated with low BW.

BJOG Editor's Choice

<scp>BJOG E</scp>ditor's <scp>C</scp>hoice

Outcome of monochorionic twins conceived by assisted reproduction

To evaluate monochorionic twins conceived by assisted reproductive technology (ART). We compared perinatal outcomes of monochorionic twins conceived by ART with their dichorionic counterparts and with spontaneous monochorionic twins. Referral center. Mothers to monochorionic and dichorionic twins conceived by ART and spontaneous monochorionic twins. None. Maternal characteristics, pregnancy complications, and perinatal outcomes. Monochorionic twin pregnancies (n = 25) comprise 7.2% of all ART twins and 4.9% of all monochorionic twins in this data set. Monochorionic pairs have a significantly worse outcome compared with dichorionic sets in terms of lower gestational age and birth weight. ART appears to increase the already high risk of monochorionicity compared with spontaneous conception: odds ratio (OR), 2.9 (1.1-7.3) for preterm birth at <32 weeks and OR, 5.9 (2.5-1.49) for birth weight <1,500g. Monochorionic twins after ART are at increased risk of adverse perinatal outcomes compared with spontaneous monochorionic twins and with dichorionic twins conceived by ART.

Dichorionic triplet pregnancies: risk of miscarriage and severe preterm delivery with fetal reduction versus expectant management. Outcomes of a cohort study and systematic review.

In trichorionic pregnancies, fetal reduction from three to two lowers the risk of severe preterm delivery, but provides no advantage in survival. Similar data for dichorionic triamniotic (DCTA) triplets is not readily available. To document the natural history of DCTA triplets and the effect of reduction on the risk of miscarriage and severe preterm delivery, compared with expectant management. Systematic search on MEDLINE, EMBASE, and the Cochrane Library. DCTA triplets with three live fetuses at 8-14 weeks of gestation, outcome data with expectant management and/or reduction, miscarriage before 24 weeks of gestation and/or severe preterm delivery before 32-33 weeks of gestation. Five studies were included. Data from these were combined with data from three centres. There were 331 DCTA triplets. The miscarriage rate was 8.9% (95% CI 5.8-13.3%) and the severe preterm delivery rate was 33.3% (95% CI 27.5-39.7%), with expectant management. The miscarriage rate was 14.5% (95% CI 7.6-26.2%) with a reduction of the monochorionic pair, 8.8% (95% CI 3.0-23.0%) with a reduction of one fetus of the monochorionic pair, and 23.5% (9.6-47.3%) with a reduction of the fetus with a separate placenta. Severe preterm delivery rates were 5.5% (95% CI 1.9-14-9%), 11.8% (95% CI 4.7-26.6%), and 17.6% (95% CI 6.2-41.0%), respectively. In DCTA triplets, expectant management is a reasonable choice when the top priority is a liveborn infant. Where the priority is to minimise severe preterm delivery, the most advisable option is fetal reduction. Further studies are needed to clarify which particular technique is advisable to optimise the outcome.

P19.16: Triplets‐surprises and dilemmas of management (case report)

The unique complications are not rare in multiples. We present the case with differential diagnoses of twin–twin transfusion syndrome, selective retardation and twin anemia polycythemia sequence in same triplets. The patient (35 yo, P0 ICSI/ET -2 embryos, one of which divided on 2, resulting in bichorionic triamniotic triplets) referred to the Riga Maternity hospital with the possible diagnosis of TTTS in monochorionic pair at 17 + 1 weeks of gestation. At admission single fetus (F1) was appropriate for gestational age with estimated delivery weight (EDW) 193g, normal Doppler and amniotic fluid (AF) index. Fetus 2 (monochorionic pair)- EDW 210g, AF dippiest pocket (DP) 8.4-9 and normal Doppler. Fetus 3 (monochorionic pair) with EDW 156g, DP 2.4, positive and absent EDF pattern in the umbilical artery, with otherwise normal Doppler, periodic filling of bladder, F2/F3 growth discordance 25%. It has been discussed with the parents that intervention at this stage was not necessary as there were no real TTTS and the polyhydramnion was not large enough to have safe entrance. On the other hand, the reducing of monochorionic twin electively was also an option, but the parents wanted to go for all three. The situation remained stable, and probably the factor of unequal sharing was the most important in the monochorionic pair. Starting from 22 + 3 constantly reverse flow in UA was recorded in F3 with ACM PSV over 1,5 MOM, that could not exclude TAPS. The optimal management in TAPS is not clear, and includes expectant management, intrauterine blood transfusion, selective feticide or fetoscopic surgery. The strict expectant follow up at 25 weeks surprisingly demonstrated constantly normalized UA and ACM flow in F3 with increased AF DP until 4 and progressive growth, whereas F2 AF DP decreased until 7. The final outcome will be reported latter on, but the case demonstrates that the multiple pregnancies still remain an enigma and more studies are necessary to improve our knowledge on the short and long-term outcome and determine the optimal management in multiples cases.

Surveillance of Monochorionic Twins

Until recently, all twin pregnancies were treated in a similar fashion. Ultrasounds were undertaken every 3 to 4 weeks to assess serial fetal growth. Monochorionic (MC) twins comprise only 20% of all twin pregnancies yet unique complications such as twin-twin transfusion syndrome (TTTS), twin reversed arterial perfusion sequence, twin anemia-polycythemia sequence, and selective intrauterine growth restriction can occur. In addition, the in utero death of one twin of a MC pair poses significant risks for death or severe neurologic morbidity in the cotwin. With the exception of discordant growth, these complications are not seen in dichorionic twinning due to the lack of placental anastomoses. In the last two decades, new technologies such as laser photocoagulation for the treatment of severe TTTS and radiofrequency ablation and bipolar cautery for selective reduction have markedly improved outcomes for many of the complications of MC twins. Thus, stratification of "low-risk" twinning (dichorionic twins) versus "high-risk" twinning (MC twins) is paramount to improved outcomes. This can be easily and accurately accomplished with first trimester ultrasound by evaluating the interface of the intertwin membrane with the placenta. This should now be the standard of care for all multiple gestations.