Risk factors associated with preterm delivery after fetoscopic laser ablation for twin-twin transfusion syndrome

Comparison of Amnio-Exchange With a Novel Synthetic Amniotic Fluid Versus Commercially Used Fluids for Fetal Therapy: An In Vivo Rodent Model

OBJECTIVE

Normal Saline (NS) and Lactated Ringer's (LR) damage human amniotic epithelium in vitro when compared with a synthetic amniotic fluid (Amnio-well, AW). We sought to evaluate the effect of amnio-exchange with NS, LR, and AW in vivo.

METHODS

On day E17.5, pregnant rats underwent amnio-exchange with NS, LR, or AW. Fetuses in each pregnant rat that did not undergo amnio-exchange acted as controls. Amnions were harvested at E20.5 and ultrastructure evaluated via electron microscopy. Protein levels of cleaved matrix metalloproteinase 9 (MMP9) and collagen 1 (Col1a) were evaluated via Western Blot. Connexin-43 expression was evaluated via immunofluorescence (IF).

RESULTS

There was an increase in amnion microfractures and epithelial cellular shrinkage with NS and LR compared with control and AW. The cleaved MMP9/Col1 ratio was increased 3.9-fold in NS (p < 0.001) and 4.5-fold LR (p = 0.0201) relative to control, whereas AW expression was similar to control (p = 0.636). Connexin-43 was also increased on IF in NS and LR relative to AW (mean gray intensity 26.5 ± 4.5, 26.5 ± 6.7, 19.2 ± 3.4, p < 0.001).

CONCLUSION

Amnio-exchange with NS and LR led to increased amniotic microfractures and collagen degradation compared with synthetic amniotic fluid. Larger models are warranted to validate or refute these findings.

Elevated middle cerebral artery peak systolic velocity and risk of death in donor twin affected by twin-twin transfusion syndrome but not twin anemia-polycythemia sequence

OBJECTIVES

To determine the association between elevated (> 1.5 multiples of the median (MoM)) middle cerebral artery (MCA) peak systolic velocity (PSV) and fetal demise of the donor twin in pregnancies complicated by twin-twin transfusion syndrome (TTTS) in the absence of twin anemia-polycythemia sequence (TAPS). Secondary objectives were to evaluate if donor or recipient MCA-PSV is associated with a risk for their corresponding fetal death, and to compare the proportion of donor fetuses with low MCA pulsatility index (PI) among donor twins with high MCA-PSV and those with normal MCA-PSV to evaluate the contribution of blood-flow redistribution to the fetal brain in donor twins with high MCA-PSV.

METHODS

This prospective cohort study included TTTS cases that underwent laser surgery between 2011 and 2022 at a single center. TAPS cases were excluded from the study. Multivariable and Poisson regression analysis were performed to explore the association between isolated elevated donor MCA-PSV and fetal demise, adjusted for TTTS stage, selective fetal growth restriction (sFGR) and other confounders.

RESULTS

Of 660 TTTS cases, donor MCA-PSV was not recorded in 48 (7.3%) cases. Of the remaining 612 patients, nine (1.5%) were lost to follow-up and 96 TAPS cases were excluded; thus, 507 cases were included in the study. High donor MCA-PSV was seen in 6.5% (33/507) of cases and was an independent risk factor for donor fetal demise (adjusted relative risk (aRR), 4.52 (95% CI, 2.72-7.50)), after adjusting for confounders. Regression analysis restricted to each Quintero TTTS stage demonstrated that high donor MCA-PSV was an independent risk factor for fetal demise of the donor in Quintero Stage II (aRR, 14.21 (95% CI, 1.09-186.2)) and Quintero Stage III (aRR, 3.41 (95% CI, 1.82-6.41)). Donor MCA-PSV in MoM was associated with fetal demise of the donor (area under the receiver-operating-characteristics curve (AUC), 0.69; P < 0.001), but recipient MCA-PSV in MoM was not associated with fetal demise of the recipient (AUC, 0.54; P = 0.44). A higher proportion of donor twins in the group with high MCA-PSV had a low MCA-PI compared to the group with normal MCA-PSV (33.3% vs 15.5%; P = 0.016).

CONCLUSIONS

Elevated donor MCA-PSV without TAPS prior to laser surgery for TTTS is associated with a 4-fold increased risk for donor fetal demise, adjusted for sFGR, TTTS stage and other confounders. Doppler evaluation of donor MCA-PSV prior to laser surgery may help stratify TTTS staging to evaluate the risk of donor fetal demise. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Impact of cannula diameter on pregnancy outcomes after minimally invasive fetal laser surgery in the treatment of twin-to-twin transfusion syndrome: A systematic review and meta-analysis

INTRODUCTION

Preterm prelabor rupture of membranes (PPROM) remains a major complication of fetal laser surgery in the treatment of twin-to-twin transfusion syndrome (TTTS). The aim of the study was to determine the impact of cannula size on pregnancy outcomes, with a particular focus on PPROM.

MATERIAL AND METHODS

The protocol was developed and registered in the PROSPERO database under registration number CRD42022333630. The PubMed, Web of Science, and EMBASE databases were searched electronically on May 18, 2022, and updated on March 2, 2023, utilizing a combination of the relevant MeSH terms, keywords, and word variants for "TTTS" and "laser". Randomized controlled trials, prospective and retrospective cohorts, case-control studies, and case reports/series with more than five participants were considered eligible for inclusion. Studies reporting the cannula diameter and PPROM rate after laser surgery in the treatment of monochorionic pregnancies affected by TTTS between 16- and 26 weeks' gestation were included. Data was extracted independently, and when appropriate, a random-effects meta-analysis was undertaken to calculate pooled estimates and their confidence intervals. Heterogeneity in the effect estimates of the individual studies was calculated using the I2 statistic. The primary outcome was PPROM rate. Secondary outcomes were survival rate, preterm birth, and incomplete surgery. The quality of the included studies was assessed using a modified quality in prognosis study tool.

RESULTS

We included a total of 22 studies, consisting of 3426 patients. Only one study was scored as low quality, seven as moderate quality, and the remaining 14 as high quality. The mean PPROM rate after laser surgery treating TTTS was 22.9%, ranging from 11.6% for 9 French (Fr) to 54.0% for 12 Fr. Subsequent meta-regression for the clinically relevant PPROM rate before 34 weeks of gestation, showed increased PPROM rates for increased cannula size (p-value 0.01).

CONCLUSIONS

This systematic review confirmed PPROM as a frequent complication of fetal laser surgery, with a mean PPROM rate of 22.9%. A larger cannula diameter relates to a significant higher PPROM risk for PPROM before 34 weeks gestation. Hence, the ideal balance between optimal visualization requiring larger port diameters and shorter operation time and more complete procedures that benefit from larger diameters is crucial to reduce iatrogenic PPROM rates.

Fetoscopic laser coagulation for twin-to-twin transfusion syndrome: a comparison of flexible 1.0/1.2 mm fetoscopes with curved sheaths of 2.7/3.3 mm2 vs. 2 mm fetoscopic lens technique with sheaths of 6.6/11.3 mm2

OBJECTIVES

Fetoscopic laser coagulation of placental anastomoses is usually performed for a treatment of twin-to-twin transfusion syndrome (TTTS). A common complication of fetoscopic laser coagulation for TTTS is preterm preliminary rupture of fetal membranes (PPROM) aggravating the neonatal outcome significantly. However, use of an flexible 1 mm fetoscope with an curved sheath could reduce iatrogenic damage of the amniotic membrane and improve neonatal outcomes after laser treatment. The aim of this study was to compare neonatal outcomes using this flexible fetoscope with curved sheath vs. use of a standard lens technique.

METHODS

Outcomes were retrospective analyzed after use of a standard lens fetoscope of 2 mm (sheath 6.63 mm2 or 11.27 mm2 for anterior placenta) and a flexible fetoscope of 1 mm or 1.2 mm (sheath 2.65 mm2 or 3.34 mm2) in two German centers of fetal surgery, performed during 2006-2019.

RESULTS

Neonatal outcome of 247 TTTS patients were analyzed including the rates of double and single fetal survival. The survival of at least one fetus was 97.2 % in the group with the ultrathin technique (n=154) compared to 88.3 % (n=93) in the group with the standard lens fetoscope (p=0.008). Survival of both fetuses was not different between groups (81.0 vs. 75.3 %). The procedure to delivery interval was significantly increased using the ultrathin fetoscope (89.1±35.0 d vs. 71.4±35.4 d, p=0.001) resulting in an increased gestational age at delivery by 11 days on average (231.9±28.1 d vs. 221.1±32.7 d, p=0.012).

CONCLUSIONS

Fetal survival can be significantly increased following TTTS using flexible fetoscope of 1 mm or 1.2 mm (sheath 2.65 mm2 or 3.34 mm2).

Perinatal outcomes following fetoscopic laser surgery for early twin-to-twin transfusion syndrome: Systematic review and meta-analysis

INTRODUCTION

Our objective was to investigate outcomes in twin-to-twin transfusion syndrome (TTTS) treated with fetoscopic laser surgery (FLS) at <18 weeks vs ≥18 weeks, and to conduct subgroup analysis of TTTS with FLS at <16 weeks vs 16-18 weeks.

MATERIAL AND METHODS

PubMed, Scopus and Web of Science were searched systematically from inception until May 2023. Primary outcome was survival, and secondary outcomes included preterm premature rupture of membranes (PPROM), preterm birth and gestational age (GA) at delivery.

RESULTS

Nine studies encompassing 1691 TTTS pregnancies were included. TTTS stage III was significantly more common in TTTS pregnancies treated with FLS at <18 weeks (odds ratio [OR] 2.84, 95% confidence interval [CI] 1.24-6.54), and procedure duration was shorter at <18 weeks (MD -5.27 minutes, 95% CI -9.19 to -1.34). GA at delivery was significantly earlier in TTTS pregnancies treated with FLS at <18 weeks (MD -3.12 weeks, 95% CI -6.11 to -0.13). There were no significant differences in outcomes, including PPROM, PPROM at <7 days post-FLS, preterm birth at <28 and <32 weeks, delivery at <7 days post-FLS, and survival outcomes, including fetal demise, live birth and neonatal survival. Similarly, TTTS stage III was more common in TTTS with FLS at <16 weeks than at 16-18 weeks (OR 2.95, 95% CI 1.62-5.35), with no significant differences in the aforementioned outcomes.

CONCLUSIONS

In early TTTS treated with FLS, outcomes were comparable between those treated at <18 weeks compared with ≥18 weeks except for GA at delivery, which was 3 weeks earlier. In the subset treated at <16 weeks vs 16-18 weeks, the procedure was feasible without an increased risk of very early preterm birth or perinatal mortality.

Management of short cervix in twin-to-twin transfusion syndrome: a role for pessary placement following fetoscopic laser surgery?

BACKGROUND

Preterm labor and delivery is a major concern for patients with twin-to-twin transfusion syndrome undergoing fetoscopic laser surgery. A preoperative short cervix is a risk factor for preterm labor. Pessary placement is a short-acting intervention that may be useful to reduce this adverse event.

OBJECTIVE

This study aimed to investigate the relationship between pessary placement and preterm delivery in monochorionic twin pregnancies with twin-to-twin transfusion syndrome and a short cervix before fetoscopic laser surgery.

STUDY DESIGN

This was a retrospective study in 2 centers, including all pregnancies affected by twin-to-twin transfusion syndrome that underwent fetoscopic laser surgery with the Solomon technique between 2013 and 2022 (center A) and 2014 and 2022 (center B) with a preoperative cervical length below 25 mm. This study explored the correlation between cervical length and fetoscopic laser surgery-to-delivery interval following active or expectant management and compared perinatal outcomes between patients managed expectantly and patients managed with pessary placement, using multivariate analysis to control for potential confounders. Patients with a cervical length below 5 mm were not included in the comparative analysis.

RESULTS

Of 685 patients, 134 met the inclusion criteria. Moreover, 21 patients were treated with a cervical cerclage and excluded from the analysis, leaving 113 patients for the final analysis. There was a significant negative correlation between cervical length at fetoscopic laser surgery and the risk of early delivery (adjusted odds ratio, 0.66; 95% confidence interval, 0.49-0.81; P<.001). The use of a pessary correlated with fewer patients delivering before 28 weeks of gestation (adjusted odds ratio, 0.28; 95% confidence interval, 0.09-0.75), fewer double neonatal demise (adjusted odds ratio, 0.2; 95% confidence interval, 0.05-0.75). Posthoc subgroup analysis suggested that these improvements were essentially noticeable for cervical lengths between 5 and 18 mm, where pessary placement was associated with an increased fetoscopic laser surgery-to-delivery interval (+24 days; 95% confidence interval, 0.86-42; P=.042) and later gestational age at delivery (+3.3 weeks; 95% confidence interval, 0.86-42; P=.035).

CONCLUSION

Patients with a moderately shortened cervix, between 5 and 18 mm, may benefit from pessary placement after fetoscopic surgery for twin-to-twin transfusion syndrome, resulting in a reduction of adverse neonatal outcomes, double neonatal demise, and severe preterm delivery.

Association of amnioinfusion volume at the time of surgery for twin-twin transfusion syndrome and latency to delivery

OBJECTIVE

To evaluate the impact of amnioinfusion and other peri-operative factors on pregnancy outcomes in the setting of Twin-twin transfusion syndrome (TTTS) treated via fetoscopic laser photocoagulation (FLP).

METHODS

Retrospective study of TTTS treated via FLP from 2010 to 2019. Pregnancies were grouped by amnioinfusion volume during FLP (<1 L vs. ≥1 L). The primary outcome was latency from surgery to delivery. An amnioinfusion statistic (AIstat) was created for each surgery based on the volume of fluid infused and removed and the preoperative deepest vertical pocket. Regression analysis was planned to assess the association of AIstat with latency.

RESULTS

Patients with amnioinfusion of ≥1 L at the time of FLP had decreased latency from surgery to delivery (61 ± 29.4 vs. 73 ± 28.8 days with amnioinfusion <1 L, p < 0.001) and increased preterm prelabor rupture of membranes (PPROM) <34 weeks (44.7% vs. 33.5%, p = 0.042). Amnioinfusion ≥1 L was associated with an increased risk of delivery <32 weeks (aRR 2.6, 95% CI 1.5-4.5), 30 weeks (aRR 2.4, 95% CI 1.5-3.8), and 28 weeks (aRR 1.9, 95% CI 1.1-2.3). Cox-proportional regression revealed that AIstat was inversely associated with latency (HR 1.1, 95% CI 1.1-1.2).

CONCLUSION

Amnioinfusion ≥1 L during FLP was associated with decreased latency after surgery and increased PPROM <34 weeks.

Perioperative risk factors of preterm delivery after fetoscopic laser photocoagulation for twin-twin transfusion syndrome

OBJECTIVE

To identify risk factors for preterm delivery (PTD) in patients who received fetoscopic laser photocoagulation (FLP) of placental anastomoses for twin-twin transfusion syndrome (TTTS).

METHODS

This retrospective cohort study prospectively analyzed and recorded perioperative data in a cohort of patients who had FLP for TTTS, identifying perioperative risk factors for PTD using a Cox proportional hazard regression model.

RESULTS

Of 304 patients included, 26 (8.6%) delivered within 4 weeks of FLP. Independent predictors of delivery within 4 weeks of FLP were a history of PTD (hazard ratio [HR]: 5.91, 95% confidence interval [CI]:1.21-28.82, p = 0.03), vaginal bleeding in the second trimester (HR: 6.62, 95% CI: 1.76-24.90, p < 0.01), and amnioreduction ≥1715 mL (HR: 3.16, 95% CI: 1.11-9.05, p < 0.03).

CONCLUSION

Patients with a history of PTD, preoperative vaginal bleeding, and amnioreduction ≥1715 mL were more likely to deliver prematurely.

A collagen plug with shape memory to seal iatrogenic fetal membrane defects after fetoscopic surgery

Iatrogenic preterm premature rupture of fetal membranes (iPPROM) after fetal surgery remains a strong trigger for premature birth. As fetal membrane defects do not heal spontaneously and amniotic fluid leakage and chorioamniotic membrane separation may occur, we developed a biocompatible, fetoscopically-applicable collagen plug with shape memory to prevent leakage. This plug expands directly upon employment and seals fetal membranes, hence preventing amniotic fluid leakage and potentially iPPROM.

Lyophilized type I collagen plugs were given shape memory and crimped to fit through a fetoscopic cannula (Ø 3 mm). Expansion of the plug was examined in phosphate buffered saline (PBS). Its sealing capacity was studied ex vivo using human fetal membranes, and in situ in a porcine bladder model.

The crimped plug with shape memory expanded and tripled in diameter within 1 min when placed into PBS, whereas a crimped plug without shape memory did not. In both human fetal membranes and porcine bladder, the plug expanded in the defect, secured itself and sealed the defect without membrane rupture.

In conclusion, collagen plugs with shape memory are promising as medical device for rapid sealing of fetoscopic defects in fetal membranes at the endoscopic entry point.

•

Shape memory can be given to collagen plugs to rapidly expand in aqueous fluids.

•

Within 1 min in aqueous fluid, collagen plugs with shape memory triple in diameter.

•

Collagen plugs with shape memory show potency to seal fetal membrane defects.

Pregnancy outcomes following early fetoscopic laser photocoagulation for twin-to-twin transfusion syndrome at 16 weeks' gestation

BACKGROUND

Ample evidence supports fetoscopic laser photocoagulation of placental anastomoses as a first-line treatment for twin-to-twin transfusion syndrome, but little is known about the outcomes following procedures conducted in the early second trimester.

OBJECTIVE

This study aimed to evaluate perinatal outcomes following early fetoscopic laser placental photocoagulation performed for twin-to-twin transfusion syndrome at 16 weeks' gestation.

STUDY DESIGN

This retrospective review included monochorionic twin pregnancies complicated by twin-to-twin transfusion syndrome necessitating fetoscopic laser photocoagulation at a single tertiary center from 2012 to 2021. The 2 cohorts were defined as cases undergoing laser surgery at 16+0/7 to 16+6/7 weeks' gestation (early laser group) and those undergoing laser surgery ≥17 weeks' gestation (standard laser group), respectively. Primary outcomes included rates of immediate chorioamniotic membrane separation, preterm premature rupture of membranes, and clinical chorioamnionitis. Secondary outcomes included twin survival rates at birth and 30 days of life. Outcomes were compared between cohorts with a P value of <.05 denoting statistical significance.

RESULTS

A total of 343 cases were included (35 early laser participants and 308 standard laser participants). The early laser group typically had higher Quintero staging at the time of the procedure. Following intervention, the early laser group had significantly higher rates of chorioamniotic separation than the standard laser group (34.3% vs 1.3% of cases; P<.001) and higher rates of preterm prelabor rupture of membranes (45.7% vs 25.0%; P=.009) and chorioamnionitis (11.4% vs 1.3%; P=.005). Even after adjustment for higher Quintero staging in the early laser group, twin survival was not significantly different between study groups.

CONCLUSION

Early laser surgery for twin-to-twin transfusion syndrome performed at 16 weeks' gestation is associated with significantly higher rates of chorioamniotic separation, preterm rupture of membranes, and chorioamnionitis. However, twin survival does not seem to be negatively impacted following early laser surgery.

Comparison of Pregnancy Outcomes of Previable and Periviable Rupture of Membranes After Laser Photocoagulation for Twin-Twin Transfusion Syndrome

OBJECTIVE

To describe the pregnancy outcomes of patients who experienced previable and periviable prelabor rupture of membranes (PROM) after the treatment of twin-twin transfusion syndrome.

METHODS

We conducted a retrospective cohort study of patients whose pregnancies were complicated by twin-twin transfusion syndrome who were treated with fetoscopic laser photocoagulation at a single fetal center and subsequently experienced PROM from April 2010 to June 2019. Outcomes were infant survival and latency from PROM to delivery. Patients were grouped by gestational age at PROM (before 26 weeks of gestation and 26 weeks or later). The group with PROM before 26 weeks of gestation was stratified by gestational age at PROM for further description of outcomes.

RESULTS

Two-hundred fifty of 653 patients (38%) developed PROM, 81 before 26 weeks of gestation and 169 after 26 weeks of gestation. In the setting of PROM before 26 weeks of gestation, the rate of survival of both twins to neonatal intensive care unit (NICU) discharge was 46.3%, compared with 76.9% in the setting of PROM at 26 weeks of gestation or later ( P <.001); the survival rate of at least one twin was 61.2% and 98.5%, respectively ( P <.001). Fourteen, 22, and 45 patients experienced PROM at 16-19 6/7, 20-22 6/7, and 23-25 6/7 weeks of gestation, respectively. Survival of both twins and at least one twin to NICU discharge was 25.0%, 47.4%, 52.8% (for two) and 33.3%, 47.4%, and 77.8% (for at least one), respectively, among those groups. Fifty-seven of the 81 patients with PROM before 26 weeks of gestation experienced a latency longer than 48 hours. In the setting of PROM before 26 weeks of gestation, when latency lasted longer than 48 hours, overall survival was improved (69.6% vs 53.7%, respectively, P =.017). With latency longer than 48 hours and PROM at 16-19 6/7, 20-22 6/7, and 23-25 6/7 weeks of gestation, survival of both twins to NICU discharge was 60.0%, 61.5%, and 60.7%, respectively, and survival of at least one twin was 80.0%, 61.5%, and 85.7%, respectively.

CONCLUSION

Earlier gestational age at PROM after laser photocoagulation is associated with longer latency but lower rates of survival. When PROM occurs before 26 weeks of gestation and latency exceeds 48 hours, rates of neonatal survival are significantly improved.

Interventions to prevent preterm delivery in women with short cervix before fetoscopic laser surgery for twin-twin transfusion syndrome

OBJECTIVE

Preoperative short cervical length (CL) remains a major risk factor for preterm birth after laser surgery for twin-twin transfusion syndrome (TTTS), but the optimal intervention to prolong pregnancy remains elusive. The objective of this study was to compare secondary methods for the prevention of preterm birth in twin pregnancies with TTTS undergoing fetoscopic laser photocoagulation (FLP), in the setting of a short cervix at the time of FLP, in five North American Fetal Treatment Network (NAFTNet) centers.

METHODS

This was a secondary analysis of data collected prospectively at five NAFTNet centers, conducted from January 2013 to March 2020. Inclusion criteria were a monochorionic diamniotic twin pregnancy complicated by TTTS, undergoing FLP, with preoperative CL < 30 mm. Management options for a short cervix included expectant management, vaginal progesterone, pessary (Arabin, incontinence or Bioteque cup), cervical cerclage or a combination of two or more treatments. Patients were not included if the intervention was initiated solely on the basis of having a twin gestation rather than at the diagnosis of a short cervix. Demographics, ultrasound characteristics, operative data and outcomes were compared. The primary outcome was FLP-to-delivery interval. Propensity-score matching was performed, with each treatment group matched (1:1) to the expectant-management group for CL, in order to estimate the effect of each treatment on the FLP-to-delivery interval.

RESULTS

A total of 255 women with a twin pregnancy complicated by TTTS and a short cervix undergoing FLP were included in the study. Of these, 151 (59%) were managed expectantly, 32 (13%) had vaginal progesterone only, 21 (8%) had pessary only, 21 (8%) had cervical cerclage only and 30 (12%) had a combination of treatments. A greater proportion of patients in the combined-treatment group had had a prior preterm birth compared with those in the expectant-management group (33% vs 9%; P = 0.01). Mean preoperative CL was shorter in the pessary, cervical-cerclage and combined-treatment groups (14-16 mm) than in the expectant-management and vaginal-progesterone groups (22 mm for both) (P < 0.001). There was no significant difference in FLP-to-delivery interval between the groups, nor in gestational age at delivery or the rate of live birth or neonatal survival. Vaginal progesterone was associated with a decrease in the risk of delivery before 28 weeks' gestation compared with cervical cerclage and combined treatment (P = 0.03). Using propensity-score matching for CL, cervical cerclage was associated with a reduction in FLP-to-delivery interval of 13 days, as compared with expectant management.

CONCLUSIONS

A large proportion of pregnancies with TTTS and a short maternal cervix undergoing FLP were managed expectantly for a short cervix, establishing a high (62%) risk of delivery before 32 weeks in this condition. No treatment that significantly improved outcome was identified; however, there were significant differences in potential confounders and there were also likely to be unmeasured confounders. Cervical cerclage should not be offered as a secondary prevention for preterm birth in twin pregnancies with TTTS and a short cervix undergoing FLP. A large randomized controlled trial is urgently needed to determine the effects of treatments for the prevention of preterm birth in these pregnancies. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Efficacy of long-term indomethacin therapy in prolonging pregnancy after fetoscopic laser surgery for twin-to-twin transfusion syndrome: a collaborative cohort study

OBJECTIVE

To evaluate the efficacy of long-term indomethacin therapy (LIT) in prolonging pregnancy and reducing spontaneous preterm birth (PTB) in patients undergoing fetoscopic laser surgery (FLS) for the management of twin-to-twin transfusion syndrome (TTTS).

DESIGN

Retrospective cohort study of prospectively collected data.

SETTING

Collaborative multicentre study.

POPULATION

Five hundred and fifty-seven consecutive TTTS cases that underwent FLS.

METHODS

Long-term indomethacin therapy was defined as indomethacin use for at least 48 hours. Log-binomial regression was used to estimate the relative risk of PTB in the LIT group compared with a non-LIT group. Cox regression was used to evaluate the association between LIT use and FLS-to-delivery survival.

MAIN OUTCOME MEASURES

Gestational age (GA) at delivery.

RESULTS

Among the 411 pregnancies included, a total of 180 patients (43.8%) received LIT after FLS and 231 patients (56.2%) did not. Median GA at fetal intervention did not differ between groups (20.4 weeks). Median GA at delivery was significantly higher in the LIT group (33.6 weeks) compared with the non-LIT group (31.1 weeks; P < 0.001). FLS-to-delivery interval was significantly longer in the LIT group (P < 0.001). The risks of PTB before 34, 32, 28 and 26 weeks of gestation were all significantly lower in the LIT group compared with the non-LIT group (relative risks 0.69, 0.51, 0.37 and 0.18, respectively). The number needed to treat with LIT to prevent one PTB before 32 weeks of gestation was four, and to prevent one PTB before 34 weeks was five.

CONCLUSION

Long-term indomethacin after FLS for TTTS was found to be associated with prolongation of pregnancy and reduced risk for PTB.

TWEETABLE ABSTRACT

Long-term indomethacin used after fetoscopic laser surgery for twin-to-twin transfusion syndrome is effective in prolonging pregnancy and reducing the risk for preterm birth; especially extreme preterm birth.

Early laser surgery is not associated with very preterm delivery or reduced neonatal survival in TTTS

OBJECTIVE

To evaluate the association of laser photocoagulation of placental anastomoses (LPA) prior to 18 weeks' gestation (early LPA) with very preterm delivery and neonatal survival in pregnancies with twin-twin transfusion syndrome (TTTS).

METHODS

This was a retrospective cohort study of monochorionic diamniotic twin pregnancies with TTTS undergoing LPA between 2002 and 2018 at two institutions. The rates of delivery < 28, < 30 and < 32 weeks' gestation, preterm prelabor rupture of membranes (PPROM) and 30-day survival of one or both infants were compared between pregnancies undergoing early LPA and those undergoing LPA ≥ 18 weeks' gestation. Regression analysis was performed to determine the association of early LPA with very preterm delivery and 30-day survival, adjusted for Quintero stage, study phase, selective fetal growth restriction, gestational age at delivery, maternal age ≥ 35 years, body mass index > 35 kg/m² , placental location, use of Seldinger method to place the operative trocar, size of the trocar, participating center, use of Solomon technique, cerclage and PPROM. Survival analysis using the Cox proportional hazard model was applied to examine the LPA-to-delivery interval according to the timing of surgery, adjusted for confounding variables.

RESULTS

A total of 414 TTTS pregnancies were included in the study, of which 68 (16.4%) underwent early LPA. In the total cohort, the incidence of delivery at < 28, < 30 and < 32 weeks' gestation was 22.7%, 39.6% and 53.4%, respectively. Survival of both twins and survival of at least one twin at 30 days were 67.5% and 90.8%, respectively. No significant difference was noted between pregnancies that underwent early LPA and those that had LPA ≥ 18 weeks in the rate of delivery < 28 weeks (19.1% vs 23.4%; P = 0.4), < 30 weeks (38.2% vs 39.9%; P = 0.8) and < 32 weeks (44.1% vs 55.2%; P = 0.1) and PPROM (29.0% vs 24.1%; P = 0.4), or in the incidence of double-twin survival (63.9% vs 68.1%; P = 0.5) and survival of at least one infant (91.8% vs 90.6%; P = 0.7) at 30 days. Early LPA was not associated with very preterm delivery or neonatal survival in the regression analyses. Early LPA was associated with a longer LPA-to-delivery interval compared with LPA performed ≥ 18 weeks (median, 106.9 days (range, 2-164 days) vs median, 69.3 days (range, 0-146 days); P < 0.001) when adjusted for confounding variables (hazard ratio, 2.56 (95% CI, 1.76-3.73); P < 0.001).

CONCLUSION

Laser surgery before 18 weeks is not associated with an increased rate of very preterm delivery and PPROM or with reduced neonatal survival when compared with LPA after 18 weeks. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Risk Factors Associated with Preterm Prelabor Rupture of Membranes after Cord Occlusion in Monochorionic Diamniotic Twins

INTRODUCTION

Preterm prelabor rupture of membranes (PPROM) is a common complication after fetal surgeries. The aim of this study was to assess risk factors for and outcomes after PPROM following cord occlusion (CO) in monochorionic diamniotic (MCDA) pregnancies.

METHODS

This was a retrospective cohort study of 188 consecutive MCDA pregnancies treated by bipolar or laser CO, either primarily because of discordant malformation (dMF) or severe selective fetal growth restriction (sFGR), or secondarily when complete bichorionization was not possible in case of twin-to-twin transfusion syndrome (TTTS) or sFGR. Intentional septostomy was performed when needed. The procedure-related PPROM was defined as rupture of membranes <32 weeks' gestation (PROM <32 weeks). Selected pre-, intra-, and early postoperative variables were analyzed by univariate and binomial logistic regression to determine they are correlated to PROM <32 weeks after CO.

RESULTS

Between 2006 and 2017, 188 cases underwent CO. Diagnosis was TTTS in 28.2% (n = 53), severe sFGR in 49.5% (n = 93), and dMF in 22.3% (n = 42). PROM <32 weeks occurred in 21.3% (n = 40), resulting in worse perinatal outcomes, as preterm birth <32 weeks occurred in 80.7% (vs. 8.3%, p = 0.000), procedure-to-delivery interval was 47.5 days (vs. 125, p = 0.000), gestational age (GA) at birth 30.0 weeks (vs. 37.7 weeks, p = 0.000), and survival 65.0% (vs. 91.1%, p = 0.000). In univariate analysis, indication, anterior placenta, cervical length, GA at surgery, operation time, amniodistention and drainage fluid volumes, chorioamniotic membrane separation, and septostomy were selected as relevant factors to be included in the regression model. In a multivariate analysis, TTTS was the only factor associated to PROM <32 weeks (OR 3.5 CI 95% 1.5-7.9).

CONCLUSIONS

PROM <32 weeks after CO increases the risk of preterm delivery. In this cohort, the membrane rupture was more likely when CO was done in the context of TTTS.

Predicting fetal and neonatal demise after fetoscopy for twin-twin transfusion syndrome using recursive partitioning

OBJECTIVE

Donor demise after laser surgery for twin-twin transfusion syndrome (TTTS) is well-characterized, but recipient demise is not, nor is neonatal death. This study aims to characterize factors associated with recipient death, donor death, and dual twin death after laser, both before and after birth.

METHODS

This is a prospective cohort study of monochorionic twin pairs who underwent laser ablation for TTTS. Risk factors for fetal and neonatal death of both twins were identified using univariable analysis and recursive partitioning, a novel statistical method to quantify contributions of each factor to outcomes.

RESULTS

In 413 twin pairs, death of both twins occurred in 9.2% (38/413), donor death in 12.1% (50/413), and recipient death in 2.4% (10/413). Recursive partitioning showed that gestational age at delivery predicts dual twin death (below 23.7 weeks, likely [p < 0.001], above 28.3 weeks, unlikely [p = 0.004]). Abnormal umbilical artery Doppler and weight discordance predict donor demise (p < 0.001 and p = 0.033, respectively). Cervical length under 16 mm predicts neonatal death of both twins (p < 0.001).

CONCLUSIONS

Parents can gain individualized information about the survival of each fetus based on variables available from preoperative and delivery variables. Short cervix and premature delivery cause significant mortality in TTTS.

Fetoscopic laser ablation in twin-to-twin transfusion syndrome: tips for counselling

Twin-to-twin transfusion syndrome (TTTS) is a serious complication that affects approximately 10-15% of monochorionic twin pregnancies. The most important role for the development of this condition is the presence of an unbalanced flow through the inter-twin vascular anastomoses. Depending on the number, type and direction of the connecting vessels, blood can be transfused disproportionately from one twin (the donor) to the other twin (the recipient). The diagnosis is defined prenatally by ultrasound and involves of two main criteria: the presence of a monochorionic diamniotic (MCDA) pregnancy; and the presence of oligohydramnios in the donor's sac- deep vertical pocket (DVP) 2 cm - and polyhydramnios in the recipient's sac- DVP>8 cm. Once diagnosed, TTTS is usually graded by using the Quintero staging system, that is composed by five stages, from oligohydramnios in the donor and polyhydramnios in the recipient twin to fetal demise in one or both twins. Photocoagulation of the anastomotic vessels, usually followed by equatorial dichorionization, it has currently become the most common fetoscopic operation today and is considered as the gold standard for stage II-IV TTTS. pPROM, chorioamniotic separation and iatrogenic preterm birth are among the most common complications of fetoscopic laser ablation, and the mean gestational age at delivery after laser procedure is about 31 weeks.

Unique Considerations: Preterm Prelabor Rupture of Membranes in the Setting of Fetal Surgery and Higher Order Pregnancies

Two unique aspects of antenatal care occur in the setting of fetal surgery and multiple gestations. As fetal interventions increase, so do the number of cases of iatrogenic preterm prelabor rupture of membranes (PPROM). Because of the amniotic sac's inability to heal, the risk of PPROM after surgery is directly correlated with the number of interventions, the size of the defect, and the surgery performed. Higher order gestations also carry an increased risk of PPROM. This paper reviews the risks and management of PPROM in the setting of the various prenatal interventions as well as in the setting of multiple gestations.

Ex-vivo mechanical sealing properties and toxicity of a bioadhesive patch as sealing system for fetal membrane iatrogenic defects

Preterm prelabor rupture of membranes (PPROM) is the most frequent complication of fetal surgery. Strategies to seal the membrane defect created by fetoscopy aiming to reduce the occurrence of PPROM have been attempted with little success. The objective of this study was to evaluate the ex-vivo mechanical sealing properties and toxicity of four different bioadhesives integrated in semi-rigid patches for fetal membranes. We performed and ex-vivo study using term human fetal membranes to compare the four integrated patches composed of silicone or silicone-polyurethane combined with dopaminated-hyaluronic acid or hydroxypropyl methylcellulose (HPMC). For mechanical sealing properties, membranes were mounted in a multiaxial inflation device with saline, perforated and sealed with the 4 combinations. We measured bursting pressure and maximum pressure free of leakage (n = 8). For toxicity, an organ culture of membranes sealed with the patches was used to measure pyknotic index (PI) and lactate dehydrogenase (LDH) concentration (n = 5). All bioadhesives achieved appropriate bursting pressures, but only HPMC forms achieved high maximum pressures free of leakage. Concerning toxicity, bioadhesives showed low PI and LDH levels, suggesting no cell toxicity. We conclude that a semi-rigid patch coated with HPMC achieved ex-vivo sealing of iatrogenic defects in fetal membranes with no signs of cell toxicity. These results warrant further research addressing long-term adhesiveness and feasibility as a sealing system for fetoscopy.

Foetal therapies and their influence on preterm birth

Foetal therapy aims to improve perinatal survival or to prevent severe long-term handicap. Foetal medicine opens a new territory by treating the foetus as a patient. The mother has nothing to gain in terms of health benefits, yet she is inherently also undergoing treatment. In utero foetal interventions can be divided into ultrasound-guided minimally invasive procedures, fetoscopic procedures and open hysterotomy procedures, which carry an inherent risk of ruptured membranes and preterm birth. In this review, we summarise the conditions that may benefit from foetal therapy and review the current therapies on offer, each with their associated risk of ruptured membrane and preterm birth. We also look into some risk limiting and preventative strategies to mitigate these complications.

Pregnancy outcomes associated with chorioamnion membrane separation severity following fetoscopic laser surgery for twin-twin transfusion syndrome

OBJECTIVE

We tested the hypothesis that increasing severity of chorioamnion membrane separation (CAS) after fetoscopic laser surgery (FLS) for twin-twin transfusion syndrome (TTTS) is associated with worse pregnancy outcomes.

METHODS

Prospective cohort of patients undergoing FLS for TTTS between 2011 and 2018. CAS was defined as separation of fetal membranes from the uterine wall on post-operative ultrasound. Patient groups were defined: Group 1: No CAS; Group 2: CAS lower than 50th centile; Group 3: CAS upper than 50th centile or complete CAS. Comparative analysis was performed.

RESULTS

Of 387 patients meeting inclusion criteria, 29 (7.5%) had CAS (median 9.8 mm [4.9-30.8 mm]). Group 1 patients were more likely to undergo FLS at later gestational age, had increased recipient maximum vertical pocket, and higher amnioreduction volume than Group 3. Group 3 had higher rates of preterm premature rupture of membrane, delivered earlier and were more likely to terminate than Group 1. Group 2 had fewer neonatal survivors than Group 1. Survival analysis for gestational age at delivery and Cox proportional hazards model indicated increased risk for early delivery in Groups 2 and 3 compared with Group 1.

CONCLUSIONS

Patients with CAS ≥9.8 mm or complete CAS after FLS for TTTS had worse obstetric and neonatal outcomes.

Distance Traveled to a Fetal Center and Pregnancy Outcomes in Twin-Twin Transfusion Syndrome

BACKGROUND

Fetoscopic laser photocoagulation (FLP) is the definitive treatment for twin-twin transfusion syndrome (TTTS). Due to variability in geographic proximity to high-volume fetal centers, many patients travel great distances to receive experienced care. We sought to determine whether distance traveled (DT) is associated with gestational age (GA) at delivery and neonatal survival.

METHODS

A prospective cohort study of patients within the continental United States referred to our center between September 23, 2011 and July 25, 2018 undergoing planned FLP for TTTS (n = 393; GA 20.6 ± 2.5 weeks; stage I: n = 50; stage II: n = 118; stage III: n = 208; stage IV: n = 17) was performed. The great-circle distance to our center was calculated using patients' home zip codes. DT was stratified into groups containing equal patient numbers and pregnancy outcomes assessed.

RESULTS

A total of 393 patients met the inclusion criteria. The threshold distance from our center was <250 miles (n = 181), 250-499 miles (n= 119), and ≥500 miles (n = 93). There was no significant difference between any of the preoperative variables among the three groups, with the exception of race and rural status. Furthermore, there was no significant association between DT and GA at delivery (p = 0.34), time interval from procedure to delivery (p = 0.37), and the number of neonatal survivors (p= 0.21). Preterm premature rupture of membranes (PPROM) at <34 weeks was highest (47.9%, p = 0.04) in the group traveling 250-499 miles.

CONCLUSION

To our knowledge, this is the largest study to show that in TTTS, DT is not associated with GA at delivery, time interval from procedure to delivery, or neonatal survival. Although PPROM at <34 weeks was higher in the group traveling 250-499 miles, there was no significant difference in GA at delivery. While patients with advanced disease may choose to seek treatment based on proximity, traveling long distances does not adversely affect pregnancy outcomes.

Maternal Complications and Hemodynamic Changes Following Intrauterine Interventions for Twin-to-Twin Transfusion Syndrome in Monochorionic Diamniotic Twin Pregnancies

Twin-to-twin transfusion syndrome (TTTS) is a challenging complication in monochorionic diamniotic (MCDA) twins. Intrauterine interventions, such as fetoscopic laser ablation and cord occlusion followed by amniodrainage, are established treatments. Little is known about maternal complications and hemodynamics following these interventions. We performed a retrospective analysis of maternal procedure-related complications and the impact of such procedures on maternal hemodynamics and blood characteristics. Within the study period, 100 women with severe TTTS treated by fetoscopic laser ablation (FLA) or cord occlusion (CO) were identified. Clinically relevant maternal complications were reported in four (4%) cases. There was a significant decrease in hemoglobin, hematocrit, and albumin between admission and postoperative measurements (all p < 0.001). Systolic and diastolic blood pressure, as well as maternal heart rate, decreased from time of skin suture to postoperative measurements (all p < 0.001). Within a 24 h interval, there was a positive correlation between hematocrit (Spearman's rho 0.325; p = 0.003), hemoglobin (Spearman's rho 0.379; p < 0.001), and albumin (Spearman's rho 0.360; p = 0.027), and the amount of amniodrainage during the intervention. Maternal procedure-related complications are relatively rare. Significant hemodynamic alterations and maternal hemodilution are common clinical findings following intrauterine interventions.

Fetoscopic Release of Amniotic Bands Causing Limb Constriction: Case Series and Review of the Literature

The aim of this study was to review the perioperative complication rates and neonatal outcomes after fetoscopic release of amniotic bands that caused bilateral limb constrictions. We present 5 cases of limb constriction by amniotic bands occurring spontaneously or following fetoscopic surgery and also include a review of 21 previously published cases. The cases were analyzed for indication, surgical technique, and postoperative follow-up. In our population and the literature, the majority of the children acquired a functional limb (75%), with few perioperative complications (15%). Fetal morbidity was mainly linked to the consequences of preterm premature rupture of the membranes (38.4%) and preterm birth (34.7 GW). The mortality rate was low (7.7%). This review only describes amniotic bands causing limb constriction, and illustrates that fetoscopic surgery for their release is technically feasible with an acceptable perioperative complication rate. However, the 75% success rate is very likely to be an overestimation of the true success rate. In view of these observations we cannot recommend treatment for cases where the fetus has been extensively affected by the bands. We believe, however, that we could consider this technique for a fraction of amniotic band syndrome cases isolated to the limb constrictions. This kind of surgery should be proposed as a potential treatment for amniotic band syndrome.

Outcome after fetoscopic laser coagulation in twin-twin transfusion syndrome - is the survival rate of at least one child at 6 months of age dependent on preoperative cervical length and preterm prelabour rupture of fetal membranes?

Purpose: Twin-to-twin transfusion syndrome (TTTS) complicates 10-15% of all monochorionic twin pregnancies. Selective laser coagulation of placental anastomoses is the only causal therapy. The aim of this study was to analyze the neonatal survival, the survival rate of at least one child at 6 months of age, and maternal outcome after laser therapy in a Swiss cohort.Material and methods: Between 2008 and 2014, 39 women were treated with fetoscopic laser procedure due to TTTS. Two women were excluded from the study because of missing informed consent or loss of follow-up. The women were divided into two groups: group 1 with a cervical length >25 mm and group 2 with a cervical length ≤25 mm. The primary end point was the survival rate of at least one child at 6 months of age and its dependence on maternal preoperative cervical length or the time interval between operation (OP)-preterm prelabour rupture of fetal membranes (PPROM). Secondary outcomes were neonatal complications and maternal complications due to the procedure. Statistical analysis was performed using the program SPSS 22. A p-value of <.05 was considered statistically significant.Results: Mean gestational age (GA) at OP of group 1 (20.3 ± 3 GW) was comparable with group 2 (21.5 ± 2.4 GW; p = .27). The GA at birth was significantly higher in group 1 (31.5 ± 5.9 GW) than in group 2 (27.0 ± 4.7 GW: p = .02). The survival rate of at least one child at 30 days and 6 months of age was 81% in group 1 and only 60% in group 2 (p = .1). PPROM <32 GW occurred in 43%. The survival rate of at least one child was significantly higher if the OP-PPROM interval was >28 days (93 versus 43%; p = .02). Major brain injury was observed in 11% of infants. Severe maternal complications (pulmonary edema) occurred in three cases (8%).Conclusions: Our survival rate of at least one child at 30 days and 6 months of age and the outcome of the mothers is well comparable to other international studies. A preoperative maternal cervical length of >25 mm and an occurrence of PPROM more than 28 days after the laser therapy is associated with a higher survival rate of at least one child at 6 months of age.

From a Disposable Ureteroscope to an Active Lightweight Fetoscope-Characterization and Usability Evaluation

The twin-to-twin transfusion syndrome is a severe fetal anomaly appearing in up to 15% of identical twin pregnancies. This anomaly occurs when twins share blood vessels from a common placenta. The complication leads to an unbalanced blood transfusion between both fetuses. A current surgical treatment consists in coagulating the shared vessels using a fetoscope with an embedded laser. Such treatment is very delicate and constraining due to limited vision and size of the insertion area. The rigidity and lack of controllability of the current used instruments add an additional difficulty and limit the choice in insertion site. This letter proposes an improved flexible fetoscope, offering an enhanced laser controllability and higher versatility regarding the location of the insertion site. A better approach angle can therefore be realized. Also, tissue damage may be further reduced. This single-handed controllable active fetoscope is obtained after adaptation of a LithoVue (Boston Scientific, Natick, MA, USA), a commercially available passive flexible ureteroscope. The LithoVue is fitted with a unique lightweight add-on actuation module foreseen of an artificial muscle and a dedicated control system. Experiments in a mixed reality trainer suggested that the proposed fetoscope is compact, ergonomic, and intuitive in use, allowing an adequate control of the flexible end.

Fetoscopic laser photocoagulation for twin-to-twin transfusion syndrome treatment: initial experience in tertiary reference center in Brazil

Objective

To evaluate the initial maternal and perinatal outcomes of fetoscopic laser photocoagulation for the treatment of twin-to-twin transfusion syndrome (TTTS) in a referral center in Brazil.

Methods

This prospective observational study analyzed 24 fetoscopic laser photocoagulation procedures at 18–26 weeks of gestation. TTTS severity was determined using the Quintero classification. Blood vessels that crossed the interamniotic membrane were nonselectively photocoagulated. The χ² test and Mann-Whitney U test were used for the statistical analysis.

Results

The mean (±standard deviation) age of pregnant women, gestational age at surgery, surgical time, gestational age at birth, and newborn weight were 32.2±4.1 years, 20.7±2.9 weeks, 51.8±16.7 minutes, 30.5±4.1 weeks, and 1,531.0±773.1 g, respectively. Using the Quintero classification, there was a higher percentage of cases in stage III (54.2%), followed by stages IV (20.8%), II (16.7%), and I (8.3%). Ten (41.7%) donor fetuses died and 14 (58.3%) donor fetuses survived until the end of gestation. Placental insertion location (anterior vs. posterior) did not affect the incidence of iatrogenic septostomy, surface bleeding, and premature rupture of membranes until the end of gestation. The death rate of donor and recipient fetuses before 24th gestational week increased with severity of TTTS.

Conclusion

The maternal and perinatal outcomes resulting from the implementation of a new minimally invasive surgical technique are in line with those obtained in major centers worldwide, considering the learning curves and infrastructures.

Histologic Chorioamnionitis and Funisitis After Laser Surgery for Twin-Twin Transfusion Syndrome

OBJECTIVE

To estimate the incidence of histologic chorioamnionitis and funisitis after fetoscopic laser surgery for the management of twin-twin transfusion syndrome.

METHODS

A case-control study was performed at the Leiden University Medical Center from 2013 to 2014. All patients with twin-twin transfusion syndrome managed with laser surgery during the study period were included and compared with a control group of all monochorionic twins not treated with laser surgery. We excluded patients with fetal demise or higher order pregnancies. Placentas were reviewed for the presence and degree of chorioamnionitis and presence or absence of fetal inflammatory response. The primary outcome was the incidence of histologic chorioamnionitis and funisitis after laser surgery. Odds ratios (ORs) and 95% confidence intervals (CIs) for primary outcomes were calculated. A P value of <.05 was considered as statistical significance.

RESULTS

Sixty-two patients treated with laser surgery were included in the study group and compared with 64 patients in the control group. The incidence of histologic chorioamnionitis was 13% (8/62) in the laser group compared with 5% (3/64) in the control group (OR 3.0, 95% CI 0.8-11.9, P=.12). Funisitis occurred in 8% (10/124) in the laser group compared with 0% in the control group (OR 11.1, 95% CI 1.3-96.9, P=.03). Histologic chorioamnionitis with or without funisitis after laser surgery was associated with a shorter laser-to-delivery interval (median 6.6 [range 3.4-14.1] compared with 13.6 [4.4-20.1] weeks, P<.01) and lower gestational age at birth (median 28.1 [range 23.1-32.6] compared with 32.7 [24.4-37.0] weeks, P<.01).

CONCLUSION

These findings suggest that laser surgery for twin-twin transfusion syndrome is associated with an increased risk of funisitis.

Preterm prelabor rupture of membranes after fetoscopic laser surgery for twin-twin transfusion syndrome

OBJECTIVE

To assess the incidence, clinical course, risk factors and outcomes of preterm prelabor rupture of membranes (PPROM) after fetoscopic laser surgery (FLS) for twin-twin transfusion syndrome (TTTS).

METHODS

This was a prospective observational cohort study of 154 consecutive cases of TTTS. PPROM was defined as rupture of membranes before 34 weeks' gestation. Procedure-to-PPROM and PPROM-to-delivery intervals were determined. Relevant preoperative and intraoperative variables were analyzed by univariate and multivariate logistic regression to determine their impact on PPROM after FLS.

RESULTS

The incidence of PPROM was 39% (n = 60), occurring at a mean gestational age of 27.2 ± 4.6 weeks. Median procedure-to-PPROM interval was 46 (range, 1-105; interquartile range (IQR), 13-66) days and median PPROM-to-delivery interval was 1 (range, 0-93; IQR, 0-13) day. Mean gestational age at delivery in cases with PPROM was 29.0 ± 4.5 weeks compared with 32.6 ± 3.9 weeks in cases without PPROM (P < 0.0001). Insertion of a collagen plug was the only significant factor found on both univariate and multivariate analysis to be associated with an increased rate of PPROM (odds ratio, 3.1 (95% CI, 1.2-8.0); P = 0.006). There was no statistically significant difference in fetal (P = 0.07) or neonatal (P = 0.08) survival between those with and those without PPROM.

CONCLUSIONS

PPROM after FLS increases prematurity by 3.6 weeks. The latency period after PPROM was 2 weeks; 50% of patients delivered within 24 h. No variable thought to be associated with PPROM after FLS was found to be significantly associated with this complication. Other etiologies and mechanisms for PPROM after FLS should be explored. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Preterm delivery after fetoscopic laser surgery for twin-twin transfusion syndrome: etiology and risk factors

OBJECTIVE

Preterm delivery after fetoscopic laser surgery (FLS) for twin-twin transfusion syndrome (TTTS) is a major complication. The causative factors leading to preterm delivery continue to be elusive and a better understanding of the risk factors could reduce complications. The objective of this study was to determine the etiology of preterm delivery after FLS for TTTS and its associated risk factors.

METHODS

This was a secondary analysis of a prospective study of 203 patients with TTTS who underwent FLS at a single center between September 2011 and December 2014. Preoperative, operative, postoperative, delivery and neonatal data were reviewed. Preterm delivery was categorized according to etiology into three groups: spontaneous (SPT), indicated (IND) and elective (ELC). Comparisons between groups were performed by ANOVA. Kaplan-Meier survival analysis was performed to compare the procedure-to-delivery interval between groups. To identify risk factors for preterm delivery, logistic regression, with calculation of relative risks (RR), was performed, with P < 0.05 considered statistically significant.

RESULTS

Mean gestational age at time of FLS was 20.6 ± 2.4 weeks and mean gestational age at delivery was 30.9 ± 4.7 weeks. Iatrogenic preterm prelabor rupture of membranes (iPPROM) occurred in 39% of cases. SPT preterm delivery occurred in 97 (48%) patients, IND preterm delivery in 65 (32%) and ELC preterm delivery in 41 (20%). In the IND group, 30 (46%) patients delivered for fetal indications, 31 (48%) for maternal indications and four (6%) for combined fetal and maternal indications. The overall chorioamnionitis rate was 6.4%; of these, nine (9%) were in the SPT group and four (6%) were in the IND group, with no case occurring in the ELC group. There was a significant difference in procedure-to-delivery interval between groups (P < 0.0001). Using variables from the ELC group as a baseline, significant risk factors for SPT preterm delivery were iPPROM (RR, 16.2 (95% CI, 4.5-57.7)), preoperative cervical length (RR, 0.96 (95% CI, 0.92-0.998)) and number of anastomoses (RR, 1.14 (95% CI, 1.02-1.27)). Significant risk factors for IND preterm delivery were iPPROM (RR, 9.6 (95% CI, 2.6-35.0)) and number of ablated anastomoses (RR, 1.13 (95% CI, 1.02-1.30)).

CONCLUSION

iPPROM and an increased number of ablated placental anastomoses were associated independently with SPT and IND preterm deliveries. A shorter preoperative cervical length was associated with SPT preterm delivery. Strategies to prevent iPPROM and for management of cervical length shortening are needed urgently in these pregnancies. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

The Impact of Entry Technique and Access Diameter on Prelabour Rupture of Membranes Following Primary Fetoscopic Laser Treatment for Twin-Twin Transfusion Syndrome

Objective: To evaluate the impact of entry method and access diameter at fetoscopic surgery for twin-twin transfusion syndrome in twin pregnancies with at least one survivor. The outcomes evaluated were prelabour rupture of membranes (PROM) and birth <4 weeks, preterm birth (PTB) <28 weeks, and latency to birth. Methods: A retrospective analysis of prospectively collected data of consecutive laser procedures from 6 centers was performed. Three entry methods (sheath + trocar; cannula + trocar; cannula + Seldinger) and 6 access diameters (2.3, 3.0, 3.3, 3.5, 3.8, 4.0 mm) were used. Exclusion criteria were subsequent invasive interventions, termination of pregnancy or double fetal death after laser. Multivariate analysis was performed to determine risk factors for the study outcomes. Results: Six hundred seventy three fetoscopic laser cases were analyzed. The use of different entry methods and access diameters did not affect PROM or birth <4 weeks, or latency from laser to birth. Access diameter was associated with PTB <28 weeks. Cervical length was associated with PROM and birth <4 weeks, and latency from laser to birth. Conclusion: Instrument choice at fetoscopic laser procedures did not affect outcomes <4 weeks. Access diameter may affect the likelihood for PTB <28 weeks. Cervical length is critically associated with obstetrical outcomes following laser surgery.

[Outcome of triplet pregnancies managed for twin-to-twin transfusion syndrome: A single center experience]

OBJECTIVES

Study the outcomes of triplet pregnancies (GGG) complicated with twin-to-twin transfusion syndrome (TTTS) treated with laser fetoscopy.

METHODS

Retrospective study of interventions, outcomes and perinatal follow-up of GGG treated for TTS.

RESULTS

Between 2002 and 2013, 25 GGG complicated by TTTS were seen in our center, 20 dichorionic and 5 monochorionic. The mean gestational age (GA) at diagnosis of TTTS was 19.7 GW (±2.4) with 2, 4, 16 and 1 pregnancies at Quintero's stage I, II, III and V, respectively. They had a fetoscopy at an average GA of 19 GW and 6 days. There were 3 (13.0%) late miscarriages. The average GA at delivery was of 29.6 GW overall (26.3 GW and 31.1 GW in monochorionic and dichorionic pregnancies respectively). The overall fetal survival rate was 57.97% (40% and 66.7% in the group of monochorionic dichorionic pregnancies, respectively). However, neonatal mortality (<28 days) is 17.5%.

CONCLUSION

GGG operated by fetoscopy for TTTS have a survival rate of three, at least 2 and at least 1 fetus of 21.7%, 69.6% and 82.6% respectively. The overall fetal survival rate is 59.97%. There is a tendency for better survival rates in dichorionic GGG compared to monochorionic GGG (P=0.079).

Thrombin Generation by Fetoscopic Trauma to the Fetal Membranes: An in vivo and in vitro Study

OBJECTIVE

We first aimed to investigate in vivo thrombin generation induced by fetoscopy, and second we used term membrane explants for measurement of thrombin generation, thrombin receptor location and induction of selected matrix metalloproteinases (MMPs) in tissue culture.

MATERIALS AND METHODS

In vivo study (37 cases): samples of amniotic fluid were taken at the beginning and end of fetoscopy (mean gestational age 26.7 weeks) and analyzed by ELISA for thrombin-antithrombin complexes. In vitro study: fetal membranes were put in culture and punctured for measurement of thrombin generation by calibrated automated thrombography and ELISA. Induction of MMP-9 and MMP-2 was analyzed by zymography. PAR-1 was localized by immunohistochemistry.

RESULTS

No significant increase in thrombin-antithrombin was measured in amniotic fluid obtained during fetoscopy. In vitro, thrombin generation induced by needle trauma of membrane cultures is correlated to the amount of plasma. Activity of MMP-9 but not MMP-2 was elevated in cultured membranes but could not be inhibited by a thrombin inhibitor. On histology, the thrombin receptor PAR-1 was located in the chorion and decidua, but not in the amnion.

DISCUSSION

Despite the influence of thrombin on punctured fetal membranes in vitro, the role of thrombin in iatrogenic preterm premature rupture of membranes is questionable.

Histologic changes of the fetal membranes after fetoscopic laser surgery for twin-twin transfusion syndrome

BACKGROUND

Preterm premature rupture of membranes remains a major complication after fetoscopic laser surgery (FLS) for twin-twin transfusion syndrome (TTTS). We studied the histologic changes of fetal membranes post-FLS and investigated a possible impact of amniotic fluid (AF) dilution.

METHODS

Fetal membranes of 31 pregnancies that underwent FLS for TTTS were investigated histologically at delivery at different sites: trocar site of recipient sac and at distance, donor sac, and inter-twin membrane.

RESULTS

The trocar insertion site on the recipient sac showed no signs of histologic hallmarks of healing. Wide-spread alteration in collagen organization and higher apoptotic index in the amnion of the recipient sac which were absent in donor's and reference membranes. To explain the mechanisms, we analyzed the AF composition of recipient sacs from TTTS pregnancies vs. GA-matched healthy singleton controls and found glucose, protein and lactate dehydrogenase activity were all significantly lower in TTTS sacs consistent with over-dilution of recipient's AF (~2-fold). In-vitro exposure of healthy amniochorion to analogous dilutional stress conditions recapitulated the histologic changes and induced apoptosis and autophagy.

CONCLUSION

Alteration in structural integrity of the recipient's amniochorion, possibly in response to dilution stress, along with ineffective repair mechanisms may explain the increased incidence of preterm birth post-FLS.

Cervical length in prediction of preterm birth after laser surgery for twin-twin transfusion syndrome

OBJECTIVES

To determine the risk factors for spontaneous preterm delivery (PTD) or preterm prelabor rupture of membranes (PPROM) at < 34 weeks' gestation after fetoscopic laser surgery for twin-twin transfusion syndrome and to identify the optimal threshold for preoperative cervical length (CL) that indicates a high risk for spontaneous PTD.

METHODS

This was a secondary analysis of data prospectively collected from 449 patients at three fetal centers. CL measurements were obtained by preoperative transvaginal ultrasound, at a gestational age of 16-26 weeks. The risk factors associated with spontaneous PTD before 34 weeks' gestation were determined using multivariable logistic regression analysis. We excluded patients with dual fetal demise and those with maternal or fetal indications for delivery without PPROM (n = 63). The optimal threshold for cervical length to predict spontaneous PTD before 34 weeks was determined using a receiver-operating characteristics (ROC) curve and Youden index. Additionally, the CL threshold for spontaneous PTD at 2-week intervals between 24 and 34 weeks was determined.

RESULTS

Spontaneous PTD before 34 weeks occurred in 206 (53.4%) of the included patients. Only the preoperative CL was significantly associated with spontaneous PTD. The preoperative CL was normally distributed with a mean of 37.6 ± 10.3 mm (range, 5-66 mm). Maternal age and parity were positively associated, and gestational age at procedure and anterior placenta were negatively associated, with CL on multivariable linear regression analysis. The area under the ROC curve for predicting spontaneous PTD with CL measurements was 0.61 (P = 0.02) and the optimal threshold was 28 mm with a Youden index of 0.19 (sensitivity and specificity of 92% and 27%, respectively). A CL measurement of < 28 mm increased the risk of spontaneous PTD for all gestational age thresholds.

CONCLUSIONS

Spontaneous PTD at < 34 weeks' gestation is associated with a preoperative CL of < 28 mm. Preventive strategies should focus on this high-risk group.

Iatrogenic Preterm Premature Rupture of Membranes after Fetoscopic Laser Ablative Surgery

Introduction: To describe the incidence and risk factors for iatrogenic premature preterm rupture of membranes (iPPROM) after fetoscopic laser surgery for the twin-to-twin-transfusion syndrome. Materials and Methods: This is a retrospective review of all patients who have undergone fetoscopic laser surgery at a single fetal treatment center since 2000. We defined iPPROM as spontaneous rupture of membranes before the onset of labor prior to 34 weeks of gestation. The iPPROM cohort was compared to the cohort without iPPROM for several preoperative, operative, and delivery characteristics. Results: Ninety-two consecutive patients were reviewed. The overall rate of iPPROM was 18.5% (n = 17). The rates of iPPROM within 1 and 4 weeks were 5.4 and 10.9%, respectively. The median interval from surgery to delivery was significantly shorter in the iPPROM group (21 vs. 62 days, p = 0.01). The mean gestational age at delivery (27.0 vs. 31.1 weeks, p = 0.02) was lower in the iPPROM group. No other characteristics studied differed significantly between the groups. Discussion: The incidence of iPPROM was substantially lower than in recent multicenter reports; however, no risk factors of iPPROM could be identified. Whether this is related to variations in surgical or anesthetic management will require further investigation.