Twin-twin Transfusion Syndrome Patients Research Articles

Randomized controlled trial of twin-twin transfusion syndrome laser surgery: the sequential trial

Intraoperative blood transfer between twins during laser surgery for twin-twin transfusion syndrome can vary by surgical technique and has been proposed to explain differences in donor twin survival. This trial compared donor twin survival with 2 laser techniques: the sequential technique, in which the arteriovenous communications from the volume-depleted donor to the volume-overloaded recipient are laser-occluded before those from recipient to donor, and the selective technique, in which the occlusion of the vascular communications is performed in no particular order. A single-center, open-label, randomized controlled trial was conducted in which twin-twin transfusion syndrome patients were randomized to sequential vs selective laser surgery. Nested within the trial, a second trial randomized patients with superficial anastomoses (arterioarterial and venovenous) to ablation of these connections first (before ablating the arteriovenous anastomoses) vs last. The primary outcome measure was donor twin survival at birth. A total of 642 patients were randomized. Overall donor twin survival was similar between the 2 groups (274 of 320 [85.6%] vs 271 of 322 [84.2%]; odds ratio, 1.12 [95% confidence interval, 0.73-1.73]; P=.605). Superficial anastomoses occurred in 177 of 642 cases (27.6%). Donor survival was lower in the superficial anastomosis group vs those with only arteriovenous communications (125 of 177 [70.6%] vs 420 of 465 [90.3%]; adjusted odds ratio, 0.33 [95% confidence interval, 0.20-0.54]; P<.001). In cases with superficial anastomoses, donor survival was independent of the timing of ablation or surgical technique. The postoperative mean middle cerebral artery peak systolic velocity was lower in the sequential vs selective group (1.00±0.30 vs 1.06±0.30 multiples of the median; P=.003). Post hoc analyses showed 2 factors that were associated with poor overall donor twin survival: the presence or absence of donor twin preoperative critical abnormal Doppler parameters and the presence or absence of arterioarterial anastomoses. Depending on these factors, 4 categories of patients resulted: (1) Category 1 (347 of 642 [54%]), no donor twin critical abnormal Doppler+ no arterioarterial anastomoses: donor twin survival was 91.2% in the sequential and 93.8% in the selective groups; (2) Category 2 (143 of 642 [22%]), critical abnormal Doppler present+ no arterioarterial anastomoses: donor survival was 89.9% vs 75.7%; (3) Category 3 (73 of 642 [11%]), no critical abnormal Doppler+ arterioarterial anastomoses present: donor survival was 94.7% vs 74.3%; and (4) Category 4 (79 of 642 [12%]), critical abnormal Doppler present+ arterioarterial anastomoses present: donor survival was 47.6% vs 64.9%. Donor twin survival did not differ between the sequential vs selective laser techniques and did not differ if superficial anastomoses were ablated first vs last. The donor twin's postoperative middle cerebral artery peak systolic velocity was improved with the sequential vs the selective approach. Post hoc analyses suggest that donor twin survival may be associated with the choice of laser technique according to high-risk factors. Further study is needed to determine whether using these categories to guide the choice of surgical technique will improve outcomes.

Subclassification of fetal growth restriction type IIa vs type IIb applied to twin-twin transfusion syndrome

Subclassification of monochorionic twins with selective fetal growth restriction (sFGR) type II into IIa vs. IIb has been proposed due to differing neonatal survival outcomes of the growth-restricted fetus after laser surgery based on preoperative Doppler findings in the middle cerebral artery (MCA) and ductus venosus (DV). There is substantial clinical overlap between sFGR and twin-twin transfusion syndrome (TTTS). To compare donor twin neonatal survival after laser surgery in cases of TTTS with concomitant donor FGR type IIa vs. IIb. This is a retrospective study of monochorionic multifetal gestations treated with laser for Stage III TTTS and concomitant donor twin FGR type II at a referral center from 2006-2021. Donor FGR type II was defined as having an estimated fetal weight (EFW) <10th percentile with persistent absent and/or reversed end diastolic velocity in the umbilical artery. Patients were then subclassified as type IIa (having normal MCA peak systolic velocities [psv] and DV Doppler waveforms) vs. type IIb (having MCA psv ≥1.5 multiples of the median and/or DV with persistent absent or reversed atrial systolic flow). We compared 30-day neonatal survival of the donor twin by FGR type IIa vs. IIb using logistic regression to adjust for relevant preoperative covariates (p<0.10 in bivariate analysis). Of 919 patients who underwent laser surgery for TTTS, 262 had Stage III donor or donor/recipient TTTS; of these, 189 (20.6%) had concomitant donor FGR type II. Twelve met exclusion criteria, yielding 177 patients (19.3%) who comprised the study cohort. Patients were subclassified as donor FGR type IIa (146 [82%]) vs. type IIb (31 [18%]). Donor neonatal survival for FGR type IIa vs. IIb was 71.2% vs. 41.9% (p=0.003). Recipient neonatal survival did not differ between the two types (p=1.000). Patients classified with TTTS and concomitant donor FGR type IIb were 66% less likely to have neonatal survival of the donor after laser surgery (adjusted OR=0.34, 95% CI 0.15-0.80; p=0.0127). The logistic regression model was adjusted for gestational age at the procedure, EFW percent discordance, and nulliparity. The c-statistic was 0.702. For patients with Stage III TTTS and concurrent donor FGR with persistent absent or reversed end diastolic velocity in the umbilical artery (i.e., FGR type II), subclassification into FGR type IIb based on elevated MCA psv and/or abnormal DV flow in the donor conveyed poorer prognosis. Although donor neonatal survival after laser surgery was lower for Stage III TTTS patients with donor FGR type IIb compared with type IIa, laser surgery for FGR type IIb in the setting of TTTS (as opposed to pure sFGR type IIb) still allows for the possibility of dual survivorship and should be offered with shared decision-making when counseling patients on management options.

Correction of fetal umbilical vein flow imbalance following laser surgery for twin-twin transfusion syndrome.

Twin-twin transfusion syndrome (TTTS) is characterized by unequal hemodynamics between the twins. We aimed to assess preoperatively the difference in umbilical vein flow (UVF) between the recipient and donor monochorionic diamniotic twins and evaluate the change in UVF following laser surgery in both twins. This was a retrospective cohort study of differences in UVF that occurred following laser surgical treatment of TTTS. Sonographic assessment of the umbilical vein before and 24 h after fetoscopic laser surgery for TTTS was performed. Umbilical vein diameter and time-averaged maximum velocity were measured, and UVF per kg (UVF/kg) was converted into a Z-score by a calculator created using gestational age as an independent variable. Z-score values were converted into centiles, which were evaluated statistically. Median differences in UVF/kg centile values were adjusted for TTTS stage and presence of arterioarterial anastomoses. The study population consisted of 363 TTTS patients. The adjusted preoperative median difference in UVF/kg centile between the recipient vs donor twin was 17.9% (-17.1% to 57.6%), P < 0.0001. The adjusted median difference in UVF/kg centile between the postoperative vs preoperative period among recipients was 2.2% (-10.8% to 13.8%), P < 0.0001, while the adjusted median difference among donors was 27.3% (8.2%-34.6%), P < 0.0001. The preoperative difference in UVF between the recipient and donor twins confirms the pathophysiology of TTTS. Postoperatively, the substantial increase in UVF of the donor twin and the relatively small increase in UVF of the recipient twin confirm that ablation of the vascular communications resulted in rapid improvement in perfusion of the donor twin. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Outcomes of laser surgery for stage I twin-twin transfusion syndrome.

A recent randomized controlled trial (RCT) demonstrated no difference in 6month survival in expectantly managed stage I twin-twin transfusion syndrome (TTTS) patients and those undergoing immediate laser surgery. We aimed to describe outcomes following immediate laser surgery at a single fetal surgery center. A retrospective study of monochorionic diamniotic twins diagnosed with stage I TTTS who underwent laser surgery between 16 and 26 gestational weeks from 2006 to 2019. The primary outcome was 6month survivorship. Intact survival was also assessed. Secondarily, outcomes were compared to the RCT expectant management group. Of 126 consecutive stage I TTTS patients, 114 (90.5%) met inclusion criteria. Median (range) gestational age at delivery was 34.1 (20.6-39.4) weeks. At 6months, the proportion of patients with at-least-one survivor in the single-center-laser cohort was 97.4%, with 88.6% dual survivorship. Neurological morbidity outcomes were available in 110 pregnancies (220 fetuses). Severe neurological morbidity occurred in 2.7% (6/220), and 6month survival without severe neurological morbidity was 90.0%. Outcomes compared favorably with the RCT expectant management group. Given favorable survival and neurological outcomes, laser surgery is a reasonable treatment option for stage I TTTS at experienced fetal surgery centers. Further study is warranted to optimize treatment strategies.

987 Preoperative factors associated with favorable outcomes following laser surgery for stage I twin-twin transfusion syndrome

The optimal treatment strategy for Quintero stage I twin-twin transfusion syndrome (TTTS) remains controversial. Identification of preoperative factors predictive of outcomes after laser surgery would be useful for counseling. The study aim was to report perinatal outcomes of stage I TTTS cases treated with laser, and to ascertain the preoperative factors associated with favorable outcomes Monochorionic diamniotic multiple gestations with a gestational age (GA) between 16 and 26 weeks with Quintero Stage I TTTS that underwent laser surgery between 2006 and 2019 were studied retrospectively. A favorable outcome was defined as dual perinatal survival with delivery at or beyond 32 weeks of gestation. Candidate preoperative factors were identified via bivariate analyses, and multivariate regression analyses were performed to determine if these factors were independently associated with the primary composite outcome. Of 124 stage I TTTS patients that underwent laser surgery, the overall mean (SD) GAs at surgery and at delivery were 21.7 (2.1) and 33.0 (3.6) weeks, respectively. Dual survivorship occurred in 109 cases (87.9%), while 99 (79.8%) cases delivered at or beyond 32 gestational weeks. The composite primary outcome occurred in 73 cases (58.9%). On bivariate analysis of preoperative patient characteristics, donor umbilical artery (UA) intermittent absent end diastolic flow (iAEDF), donor UA systolic velocity/diastolic velocity (SD ratio), estimated fetal weight (EFW) percent discordance, and cervical length were associated with the outcome. Multiple logistic regression modeling identified donor UA forward flow (OR 2.38 [95%CI 1.03-5.56], p=0.0433) and cervical length (cm) (1.43 [95%CI 1.02-2.00], p=0.0395) as the only associated factors, yielding a c-statistic of 0.64. With 88% overall dual survivorship and 33 weeks mean GA at delivery, laser surgery for stage I TTTS remains a reasonable option. Robust predictors of favorable outcomes that could be incorporated into preoperative counseling were not identified.

353 Twin-twin transfusion syndrome (TTTS) and the definition of recipient polyhydramnios

Controversy exists regarding the threshold of recipient twin polyhydramnios required to diagnose TTTS beyond 20 weeks gestational age (GA). One criterion set (North American) requires the amniotic fluid maximum vertical pocket for the recipient twin (MVP-R) to measure ≥ 8 cm regardless of GA, while another (European) uses an MVP-R ≥ 10 cm at a GA ≥ 20 weeks. The aim of this study was to characterize the laser treated TTTS patients that would be excluded from laser surgery according to the European criteria. Monochorionic diamniotic twins diagnosed with TTTS from 20-26 weeks who underwent laser surgery at our center were studied. MVP-R ≥ 8 cm was used to diagnose TTTS, regardless of GA. Patients were retrospectively divided into two groups: (Group A) MVP-R ≥ 8 and < 10 cm and (Group B) MVP-R ≥ 10 cm, and association with survivorship outcomes was tested. Results are reported as median (range). Of the 366 studied patients, 53 (14.5%) had an MVP-R ≥ 8 and < 10 cm (Group A), and 313 (85.5%) had an MVP-R ≥ 10 cm (Group B). Groups A and B did not differ in Quintero stage. Notably, 60.4% of Group A patients were stage III or IV. Compared to Group B, Group A was diagnosed with TTTS at an earlier GA [21.1 (20.0-26.0) vs. 22.1 (20.0-26.0) weeks; p=0.0037] and had a higher prevalence of donor growth restriction (81.1% vs 65.5%; p=0.0260). Rates of at-least-one twin and dual twin survivorship between Group A and B were (98.1% vs 95.8%; p=0.7023) and (79.2% vs 83.4%, p=0.4369), respectively. Logistic regression models adjusted for perioperative characteristics showed no difference in outcomes (Group B reference) [donor twin survival: OR 0.64 (0.29-1.42), p=0.2753; and dual survivors: OR 0.90 (0.42-1.91), p= 0.7757]. Restriction of the definition of TTTS to MVP-R ≥ 10 cm beyond 20 weeks GA would exclude 14.5% of patients from laser surgery, of which the majority have advanced stage TTTS. A unifying criterion of an MVP-R of ≥ 8 cm regardless of GA would allow inclusion of these patients and access to surgical management.

543 Does the time of laser usage during surgery for twin-twin transfusion syndrome impact pregnancy outcomes?

Selective fetoscopic laser photocoagulation (SFLP) performed in twin-twin transfusion syndrome (TTTS) results in placental perfusion changes. Our objective is to evaluate pregnancy outcome in relation to the time of laser firing during surgery. Retrospective cohort study at a single fetal center of all TTTS patients treated with SFLP from April 2010 to June 2019. At the time of surgery, the time of laser firing was documented. Data collected was maternal demographic data, pregnancy characteristics and outcomes, surgical characteristics, fetal survival, and postoperative complications. Laser time was not normally distributed, thus the upper quartile (7.6 minutes (mins)) was selected as the cut-off for increased laser time. Primary outcomes were pregnancy outcomes, including survival and risk of preterm birth (PTB) at ≤26, 28, and 32 weeks. Data was analyzed using chi2, student’s t-test, multivariate logistic regression, and linear regression as appropriate. 580 patients met inclusion criteria. Median laser time was 4.9 min (range 0.2-22 min). Baseline characteristics were similar amongst groups (table). Surgery laser time >7.6 min was significantly associated with increase in number of total vessels ablated, higher rate of microseptostomy (39% vs 26%, p < 0.001), higher laser energy level (17298 vs 8608 joule, p < 0.001), and lower donor survival (71% vs 82% p = 0.004) as compared to time <7.6min respectively. Laser time <7.6min was also associated with higher rates of double survival (81.7% vs 70.1%, respectively, p = 0.034). Surgery laser time was not associated with any increased risk of PTB prior to 26, 28, and 32 weeks. Longer surgery laser time >7.6 min was associated with significant decrease in donor and double fetal survival rate. Surgery laser time did not impact gestational age at delivery. This information becomes important in surgical training for SFLP and patient counseling.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Study on the expression of interleukins in patients with twin-twin transfusion syndrome

Twin-twin transfusion syndrome (TTTS) is an unusual and serious condition that occurs in twin pregnancies when identical twins share a placenta but develop discordant amniotic fluid volumes. The TTTS has a high risk of fetal death and birth defects if left untreated. IL-1β, IL-6 and IL-8 have been shown to play an important role in preterm birth in twin pregnancies, which is one of the consequences of TTTS. This study quantified plasma levels of IL-1β, IL-6 and IL-8 in twin pregnant women with (n = 52) and without TTTS (n = 73) by ELISA and analyzed the association of interleukin expression levels with TTTS. The results showed that plasma concentrations of IL-1β and IL-8 were low and not significantly different between the first trimester and the second trimester of pregnancy, between the patients with and without TTTS or between patients with TTTS before and after treatment. IL-6 levels showed no significant difference between first trimester and second trimester of pregnancy or between patients with and without TTTS. Importantly, IL-6 levels were significantly elevated in TTTS patients after surgical treatment compared to those before surgical treatment. In conclusion, IL-6 may be considered as a potential marker for the prognosis of surgical treatment of TTTS.

Percent Absent End-Diastolic Velocity in the Umbilical Artery and Donor Twin Demise after Laser Surgery for Twin-Twin Transfusion Syndrome

Introduction: To examine the association of preoperative absent end-diastolic velocity (AEDV) and percent AEDV (%AEDV) in the umbilical artery (UA) with donor twin intrauterine fetal demise (IUFD) after laser surgery for twin-twin transfusion syndrome (TTTS). Methods: We performed a retrospective study of stage III/IV TTTS patients who underwent laser surgery from 2006 to 2016. Donors were classified as having preoperative persistent AEDV (yes/no). %AEDV was calculated for those with AEDV as 100× the proportion of the total cardiac cycle in AEDV. Using multiple logistic regression, we tested for an association between the outcome donor IUFD and AEDV risk factors (part 1) and %AEDV (part 2). We stratified these analyses by estimated fetal weight (EFW) discordance ≥20 versus <20%. Results: Of 344 cases, 153 (44.5%) donors had AEDV. Part 1 did not confirm an independent association between AEDV and donor IUFD. In the part 2 analysis of the 153 patients with AEDV, %AEDV was a positive risk factor for donor IUFD only in those with discordance (n = 129) (OR 1.04, 95% CI 1.01–1.08, p = 0.0278) when adjusting for %EFW discordance, presence of arterioarterial anastomoses, and multiparity. Discussion: Among stage III/IV TTTS patients with AEDV, %AEDV was a risk factor for donor IUFD only in the presence of EFW discordance.

The outcomes of transient elevation of maternal liver enzymes preceding laser treatment for twin-twin transfusion syndrome

BackgroundA proportion of twin-twin transfusion syndrome (TTTS) patients may have elevated liver enzymes (ELEzs) before fetoscopic laser therapy, but the incidence of ELEzs before laser therapy and the association with the perinatal outcomes after laser therapy remain unclear. MethodsFrom October 2008 to April 2015, 93 patients with TTTS who received fetoscopic laser therapy at our hospital were included in this study, and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were measured within 24 h before therapy. If ELEzs (AST > 34 U/L or ALT > 36 U/L) were observed before therapy, the AST and ALT levels were evaluated within 24 h after therapy. The pre-operative characteristics and post-therapy outcomes were compared between patients with and without ELEzs. ResultsAmong 93 TTTS patients before laser operation, 18 patients (were found with ELEzs (19.4%) before laser therapy. In 17 (94.4%) of the 18 cases, their liver enzymes values dropped after laser surgery. Maternal body mass index, age, gestational age of laser therapy, hemoglobin level before laser therapy and survival rates after laser therapy were not significantly different between TTTS with and without ELEzs. The maternal hemoglobin dropped significantly from 10.8 [1.6] g/dL before surgery to 9.6 [1.5] g/dL after laser therapy in TTTS with ELEzs (p < 0.001). ConclusionAn elevated liver enzyme was not associated with poor perinatal outcomes in patients with TTTS after laser therapy. The authors suspected that the reduced liver enzymes values after laser therapy could partly arise from the hemo-dilution effect.

The roles of superficial anastomoses in twin-twin transfusion syndrome

ObjectiveWe aimed to evaluate whether types of vascular anastomoses affect fetal demise (FD) in twin-twin transfusion syndrome (TTTS) after fetoscopic laser photocoagulation (FLP). MethodsAll TTTS patients who underwent FLP in our institution from 2005 to 2017 were included. We described vascular anastomoses during FLP as either arterio-arterial (AA), veno-venous (VV), or arterial-venous (AV), and abnormal fetal Doppler waveforms before FLP. We also analyzed risk factors for FD following FLP. ResultsIn total, 184 TTTS placentas following FLP were analyzed (36 cases of donor-only FD, 12 cases of recipient-only FD, 3 cases of double FD, and 133 cases of both alive). AA anastomoses prevalence, absent or reverse end-diastolic velocity of umbilical artery (UAAREDV) of donor before FLP, gestational age at the time of FLP and operation time of FLP were independent risk factors for donor FD. VV anastomoses prevalence and UAAREDV of recipient before FLP were independent risk factors for recipient FD. VV anastomoses prevalence was higher in double FD cases than in FD of one twin or both alive (p = 0.002). AV anastomoses number and number of cases with more AV anastomoses from donor to recipient were not significantly different between FD and non-FD cases. DiscussionAA anastomoses are associated FD of the donor following FLP and may protect the donor from hypovolemia before FLP. VV anastomoses are detected more frequently in FD of the recipient and double FD placentas following FLP and may rescue hypervolemia of the recipient or circulations of both fetuses before FLP.

Percent Absent End-Diastolic Velocity and Risk of Donor Twin Demise in Twin-Twin Transfusion Syndrome [19A

INTRODUCTION: We examined the association of percent absent end-diastolic velocity (%AEDV) in the umbilical artery with intrauterine fetal demise (IUFD) of the donor twin after laser surgery in patients with twin-twin transfusion syndrome (TTTS) Quintero stages III/IV. %AEDV was calculated as 100x the proportion of total cardiac cycle spent in AEDV. METHODS: Retrospective study of TTTS stage III/IV patients between 2006 and 2016. Donors were classified as having persistent AEDV (yes/no). In Part 1, we used multiple logistic regression analysis to test whether AEDV was associated with donor IUFD. We stratified these analyses by estimated fetal weight (EFW) discordance of ≥20% or <20%. In Part 2, we used similar models to test only those with AEDV to determine whether %AEDV was associated with IUFD. This was an IRB approved study. RESULTS: Of 344 stage III/IV TTTS cases, 153 (44.5%) donors had preoperative AEDV. In Part 1, we did not confirm an independent association between AEDV and donor IUFD. In Part 2, patients with AEDV who were discordant (N=129), had the following characteristics associated with donor IUFD: %AEDV (OR 1.04, 95% CI 1.01-1.08), %EFW discordance (OR 1.07, 95% CI 1.02-1.13), and presence of arterioarterial anastomoses (OR 5.15, 95% CI 2.06-12.89). In the non-discordant group (N=24), no association was found between %AEDV and donor IUFD. CONCLUSION: The presence of preoperative persistent AEDV was not an independent risk factor for donor IUFD in stage III/IV TTTS patients undergoing laser surgery. However, among donors with preoperative AEDV and EFW discordance ≥20%, %AEDV was positively associated with donor IUFD.

Characteristics of referred patients with twin-twin transfusion syndrome who did not undergo fetal therapy.

Abundant research has reported twin-twin transfusion syndrome (TTTS) outcomes following fetal therapy. Our research describes TTTS patients who did not undergo fetal therapy. Records from TTTS pregnancies evaluated at 16 to 26 gestational weeks were reviewed between January 2006 and March 2017. The study population comprised subjects who did not undergo fetal therapy. Based on initial consultation, patients were grouped as nonsurgical vs surgical candidates. TTTS progression and perinatal outcomes were assessed. Of 734 TTTS patients evaluated, 68 (9.3%) did not undergo intervention. Of these, 62% were nonsurgical candidates and 38% were surgical candidates. Nonsurgical candidates were ineligible for treatment because of fetal demise or maternal factors (placental abruption, severe membrane separation, and preterm labor). Of surgical candidates, 11 underwent expectant management, eight elected pregnancy termination, and seven planned fetal intervention but had a complication before the procedure. TTTS progression occurred in 10 (15.2%) of 66 cases. Neonatal survival in 64 cases was as follows: in 41 (64%), no survivors; in 11 (17.2%), one survivor; and in 12 (18.8%), two survivors. Nine percent of referred TTTS patients did not undergo fetal therapy, with many ineligible because of morbidity between referral and consultation. Studies of TTTS should acknowledge this subgroup and circumstances leading to lack of treatment.

Incidental Septostomy after Laser Surgery for Twin-Twin Transfusion Syndrome: Perinatal Outcomes and Antenatal Management

Introduction: Incidental septostomy, or inadvertent perforation of the twins’ dividing membranes, can create a functional monoamniotic twin pregnancy. Our aim was to describe the perinatal outcomes and antenatal management of patients with incidental septostomy after laser surgery for twin-twin transfusion syndrome (TTTS). Materials and Methods: Monochorionic diamniotic multiple gestations with a gestational age (GA) between 16 and 26 weeks that underwent laser surgery from March 2006 to December 2015 were studied retrospectively. Perinatal outcomes were compared for patients with and without an incidental septostomy. A subgroup analysis was performed to evaluate antenatal management. Results: Of 532 TTTS patients who underwent laser surgery, incidental septostomy occurred in 34 (6.4%). Compared to all others, patients with a septostomy had an earlier median (range) GA at delivery (30.8 [18.6–37.9] vs. 34.0 [19.3–40.4] weeks, p < 0.0001) and lower 30-day survival of at least one twin (85.3 vs. 94.6%, p = 0.0452). We found no evidence that inpatient fetal surveillance was protective. Discussion: Incidental septostomy in TTTS patients treated via laser surgery appeared to be associated with lower GA at delivery and perinatal survival of at least one twin. Further study is required to determine the optimal antenatal surveillance strategy.

P29.04: The roles of superficial anastomoses with Twin–twin transfusion syndrome

The roles of superficial anastomoses with Twin–twin transfusion syndrome (TTTS) are previously reported. Arterio-arterial (AA) anastomoses may rescue a blood transfusion due to blood pressure imbalance between both twins, however, the roles of veno-venous (VV) anastomoses remain still unclear. The aim of this study was to evaluate whether vascular anastomoses affect intrauterine fetal death (IUFD) after laser surgery. All TTTS patients underwent laser surgery from 2005 to 2012 were included in this study. We described vascular anastomoses, umbilical cord insertion abnormalities (velamentous or marginal), abnormal waveforms of fatal Doppler and how to coagulate in laser surgery. We analysed risk factors for IUFD. A total of 129 TTTS placentas were analysed (IUFD of donor, n=29: IUFD of recipient, n=12: double IUFD, n=3: both alive, n=91). The prevalence of AA anastomoses was higher in the IUFD of donor than in the control (p<0.001). Multiple logistic analysis revealed the prevalence of AA anastomoses, gestational age of laser surgery and anterior placenta were independent risk factors for IUFD of donor after laser surgery. The prevalence of VV anastomoses was higher in the IUFD of recipient and double IUFD than in the control (p=0.032, 0.004). AA anastomoses have relation to IUFD of donor after laser surgery and may protective hypovolemic of donor. VV anastomoses are detected frequently in IUFD of recipient and double IUFD placentas after laser surgery and may rescue recipient or both fetuses.

The experience of modified sequential selective laser photocoagulation of communicating vessels technique for twin-twin transfusion syndrome

Objective: Fetoscopic laser photocoagulation of vascular anastomoses (FLP) is the essential choice in twin-twin transfusion syndrome (TTTS). We proposed that the modified sequential selective laser photocoagulation of communicating vessels (modified SQLPCV) to clarify the perinatal outcomes in TTTS. Methods: The modified SQLPCV was designed with the following order: 1, artery-to-artery anastomoses; 2, venous-to-venous anastomoses; 3, artery-to-venous anastomoses from donor to recipient; and 4, artery-to-venous anastomoses from recipient to donor. The perinatal outcomes were present in TTTS patients who underwent the modified SQLPCV. Results: A total of 203 women underwent modified SQLPCV. The mean pregnancy prolongation period was 83 days, and the mean gestational age at delivery was 33 weeks (range 23–40 weeks). There was a significantly lower rate of recipient fetal demise than donor fetal demise (4% vs. 13%; p < .01). The survival rate of zero and one were respectively 6% (13/203) and 19% (39/203). Two survivors were seen in 74% (151/203), and at least one survivor in 94% (190/203). Univariate and multivariate analysis showed that abnormal fetal Doppler measurements in donor were correlated with donor demise after surgery. Conclusions: The modified SQLPCV represents satisfactory outcomes for fetuses complicating with TTTS.

Decreased Total Placental Mass Found in Twin-Twin Transfusion Syndrome Gestations with Selective Growth Restriction

Introduction: We examined placental weight characteristics associated with donor selective intrauterine growth restriction (SIUGR) among patients with twin-twin transfusion syndrome (TTTS) who underwent laser surgery. Materials and Methods: Fresh placental specimens were studied. Pregnancies with higher-order multiples, fetal demise, or disrupted or nonsubmitted placental specimens were excluded. Placental characteristics prospectively collected included total placental weight, individual placental weight, and placental share. Data were compared between pregnancies with SIUGR (TTTS + SIUGR group) and those without SIUGR (TTTS-only group). Results: Of 369 consecutive patients who underwent laser surgery for TTTS, 155 (42%) met inclusion criteria: 91 with TTTS + SIUGR and 64 with TTTS-only. Compared to the TTTS-only group, patients in the TTTS + SIUGR group had a lower total placental weight (608 ± 163 vs. 687 ± 224 g, p = 0.012), with a lower donor individual placental weight (237 ± 91 vs. 291 ± 124 g, p = 0.002), but no apparent difference in the individual placental weight of recipient twins (371 ± 109 vs. 396 ± 133 g, p = 0.211). Donor placental share was smaller in those pregnancies affected by SIUGR (38.7 ± 9.6 vs. 42.3 ± 9.8%, p = 0.029). Discussion: TTTS patients with SIUGR had a lower total placental weight and a lower donor individual placental weight compared to those without SIUGR. These findings suggest that differences in donor individual placental weights for SIUGR gestations may not solely be related to differences in placental share.

Pre-Operative Twin Anemia/Polycythemia in the Setting of Twin-Twin Transfusion Syndrome (TTTS)

Introduction: Twin-twin transfusion syndrome (TTTS) and twin anemia-polycythemia sequence (TAPS) are classified as distinct clinical disorders associated with unbalanced blood flow through placental vascular communications. Typically, TAPS placentas demonstrate few <1 mm arteriovenous (AV) communications, and at fetoscopy the twins are visibly pale and plethoric. Materials and Methods: In a cohort of TTTS patients who underwent laser surgery, those with preoperative findings suggestive of anemia/polycythemia (AP) were compared to those with TTTS alone. AP was defined as middle cerebral artery peak systolic velocity in one twin >1.5 multiples of the median (MoM), and <1.0 MoM in the other. Results: Of 369 TTTS patients, 9 (2.4%) met criteria for preoperative AP. The mean number (±SD) of AV communications in the TTTS + AP group was 5.6 ± 5.7, compared with 8.8 ± 4.8 in the TTTS-alone group (p = 0.013). Five TTTS + AP patients (56%) had a few thin AV communications (mean 2.8 ± 1.6); all 5 had visibly pale and plethoric twins. The remaining 4 (44%) had large or numerous anastomoses (mean 10.5 ± 6.8); none had fetal skin color discordance. Discussion: Preoperative AP affected 2% of TTTS patients. Of these, approximately half had placental and skin color findings typically reported with isolated TAPS.

Perinatal survival in cases of twin–twin transfusion syndrome complicated by selective intrauterine growth restriction

Objective: To evaluate the impact of selective intrauterine growth restriction (SIUGR) on monochorionic multiples treated with selective laser photocoagulation of communicating vessels (SLPCVs) for twin-twin transfusion syndrome (TTTS).Methods: Perinatal survival was compared among TTTS patients with and without SIUGR. The TTTS + SIUGR group was defined as TTTS patients with donor twin weight <10th percentile. Multivariable logistic regression analyses identified factors associated with 30-day survival.Results: Of 369 patients, 65% (N = 241) had TTTS + SIUGR. Thirty-day donor twin survival for the TTTS-only group was 84% versus 75% in the TTTS + SIUGR group (p = 0.0348). Stage III donor involved (stage III donor, donor/recipient) TTTS + SIUGR patients (N = 110) had 66% 30-day donor survival. Multivariable logistic regression demonstrated that the TTTS-only group was twice as likely to achieve donor survival compared to the TTTS + SIUGR group (OR 2.01, 95% CI 1.11–3.66, p = 0.0214). In the TTTS + SIUGR group, patients not classified as stage III donor-involved were twice as likely to achieve donor survival as stage III donor-involved patients (OR 2.02, 95% CI 1.10–3.71, p = 0.0226).Conclusions: SIUGR, present in two-thirds of TTTS patients, was a risk factor for decreased donor survival. Patients with donor SIUGR and umbilical artery persistent or reversed end-diastolic flow (Quintero Stage III Donor-involved) were especially at risk.

164: Midtrimester isolated polyhydramnios in monochorionic diamniotic multiple gestations

164: Midtrimester isolated polyhydramnios in monochorionic diamniotic multiple gestations