Selective Laser Photocoagulation Of Communicating Vessels Research Articles

Doppler Finding, Cardiovascular Function Assessment, and Fetuses' Survival Following the Fetoscopic Laser in Twin-to-Twin Transfusion Syndrome.

Introduction: This study aimed to evaluate the effectiveness of selective laser photocoagulation of communicating vessels (SLPCV) on cardiac function in twins with twin-to-twin transfusion syndrome (TTTS). Methods: This retrospective cohort study evaluated 178 women with twin pregnancies complicated with TTTS and scheduled for SLPCV between 16 and 26 weeks of gestation. The severity of TTTS was determined by Quintero staging and the severity of cardiovascular disorders by the CHOP (Children's Hospital of Philadelphia) score. Patient survival was evaluated through a one-month-after-birth follow-up of fetuses. Results: The study revealed significant improvements in Doppler indices in both donors and recipients after SLPCV. The CHOP score also significantly decreased after the intervention. One-month-after-birth survival rates were 55.1% in donors and 56.7% in recipients. Some Doppler indexes of fetuses before SLPCV could predict survival until one month after birth. Conclusion: The study suggests that SLPCV can improve cardiac function in fetuses with TTTS and that some Doppler indexes can predict survival outcomes. Additionally, the severity of TTTS can be a powerful indicator of the severity of cardiovascular complications.

Selective intrauterine growth restriction (SIUGR) type II: proposed subclassification to guide surgical management

Background Optimal surgical management of monochorionic diamniotic twins complicated by selective intrauterine growth restriction (SIUGR) type II is unknown. Surgical management may involve selective laser photocoagulation of communicating vessels (SLPCV), which offers the possibility of dual twin survivors versus umbilical cord occlusion (UCO) of the SIUGR twin. Objective To identify patient characteristics associated with SIUGR twin survival for those undergoing SLPCV. Study design All patients studied were those who underwent fetal treatment for SIUGR type II at our center from 2006–2018. SIUGR type II was defined as an estimated fetal weight <10th percentile with persistent absent and/or reversed end diastolic flow in the umbilical artery of the SIUGR twin, in the absence of twin-twin transfusion syndrome. Patients were offered SLPCV versus UCO, and those undergoing SLPCV, patient characteristics associated with 30-day survival of the SIUGR twin were examined using bivariate analysis and multiple logistic regression models. Results Fifty-four consecutive SIUGR type II patients were treated, 45 via SLPCV and nine via UCO. Of the 45 SLPCV cases, there were 16 (35.6%) with SIUGR twin (and dual) survival. SIUGR twin survival appeared associated with middle cerebral artery (MCA) peak systolic velocity (psv) <1.5 multiples of the median, and forward atrial systolic flow in the ductus venosus (DV). In a post hoc analysis, we subsequently categorized patients as: SIUGR type IIa (N = 32 (71.1%)): normal MCA psv, and normal DV waveform, versus SIUGR type IIb (N = 13 (28.9%)): MCA psv ≥1.5 multiples of the median, and/or DV with absent or reversed atrial systolic flow. Thirty-day survival of the SIUGR twin was 50% for type IIa and 0% for type IIb. Conclusion Over one-third of SIUGR type II patients experienced dual survival after treatment with laser surgery. Normal MCA psv and normal DV waveforms were associated with SIUGR type II survival of the SIUGR twin. Post hoc exploration and subclassification of SIUGR type II patients by preoperative Doppler indices created two groups, one (type IIa) with 50% survival and one (type IIb) with 0% survival of the SIUGR twin after laser surgery. Upon further confirmation, these findings may provide guidance for counseling patients and conducting fetal therapy.

Membrane Separation and Perinatal Outcomes after Laser Treatment for Twin-Twin Transfusion Syndrome

Introduction: Postoperative membrane separation is a complication of selective laser photocoagulation of communicating vessels (SLPCV) for the treatment of twin-twin transfusion syndrome (TTTS). Objective: The aim of this work was to determine whether a quantitative grading system of membrane separation following SLPCV was associated with preterm premature rupture of membranes (PPROM) and preterm delivery (PTD). Methods: Patients with membrane separation after SLPCV on postoperative day 1 were stratified into greatest width of separation <1 cm (Group A) or ≥1 cm (Group B) and compared to patients without separation by the following outcomes: PPROM ≤21 postoperative days, PTD <28 gestational weeks, and PTD <32 gestational weeks. Results: Of 654 patients, 123 (18.8%) had membrane separation. Of these, 120 patients were eligible for study and divided into Groups A (n = 91) and B (n = 29). Multiple logistic regression analysis yielded associations with PPROM ≤21 days for Groups B (OR 8.60, 95% CI 3.38–21.90, p < 0.0001) and A (OR 2.39, 95% CI 1.05–5.40, p = 0.0369) compared to those without membrane separation. In similar models, Group B was associated with PTD <32 weeks (OR 2.41, 95% CI 1.10–5.28, p = 0.0274). Conclusion: Postoperative membrane separation was associated with an increased risk of PPROM ≤21 days. Membrane separation ≥1 cm had a higher risk of PTD <32 weeks.

228: Monochorionic twins with Selective Intrauterine Growth Restriction (SIUGR) type II: Laser surgery versus cord occlusion

The optimal management of monochorionic multiple gestations complicated by SIUGR Type II is unknown. We compare the perinatal outcomes of these patients after undergoing selective laser photocoagulation of communicating vessels (SLPCV) versus umbilical cord occlusion (UCO) of the SIUGR twin. All patients undergoing fetal treatment for SIUGR Type II from 2006 to 2018 at our center were retrospectively studied. SIUGR Type II was defined as an estimated fetal weight <10th percentile (Hadlock) with persistent absent and/or reversed end diastolic flow in the umbilical artery of the SIUGR twin, in the absence of twin-twin transfusion syndrome. SIUGR Type II patients desiring fetal intervention were offered the option of SLPCV versus UCO. All cases of UCO were presented to the fetal therapy ethics board for approval. Pregnancy and perinatal outcomes including 30-day survival were compared between the two groups. Of 49 SIUGR Type II patients who underwent fetal treatment, 41 (83.7%, 95% CI ± 10.3%) chose SLPCV; 8 (16.3%) chose UCO. In the UCO group, 4 surgeries were performed using radiofrequency ablation and 4 using laser occlusion. An anomaly in the SIUGR twin was noted in 4 (50%) of the UCO group only (p<0.001). Surgical characteristics by treatment group are shown in the Table. The SLPCV versus UCO groups had a similar mean gestational age (GA) at surgery (21.5 ± 2.6 vs. 20.2 ± 2.0 weeks, p=0.137), anterior placental location (48.8% vs. 50.0%, p=0.709), and percent discordance in weight at time of surgery (36.4 ± 12.3 vs. 46.9 ± 15.2 percent, p=0.0832). Regarding perinatal outcomes, the SLPCV versus UCO groups had a similar mean delivery GA (33.2 ± 4.2 vs. 31.6 ± 7.2 weeks, p=0.829), 30-day survival of the appropriately grown (AGA) twin (38/41[92.7%] vs. 7/8 [87.5%], p=0.522), survival of the SIUGR twin (13/41 [31.7%] vs. 0/8 [0%], p=0.090), and birth weight of the AGA twin (2,044 ± 717 vs. 1,969 ± 841 grams, p=0.8544). In the SLPCV group, the birth weight of the SIUGR twin was 1,136 ± 572 grams. When given the option, most patients with SIUGR Type II proceeded with SLPCV, notwithstanding its various operative challenges. SLPCV achieved similar perinatal outcomes and survival of the AGA twin compared to UCO, with the advantage of survival of 32% of the SIUGR twins.

Audit of immediate outcomes for MCDA twins following laser therapy for twin-twin transfusion syndrome at the NSW Fetal Therapy Centre.

To audit immediate pregnancy and neonatal outcomes of selective laser photocoagulation of communicating vessels (SLPCV) for twin-twin transfusion syndrome (TTTS) at the New South Wales Fetal Therapy Centre. Retrospective cohort study of 151 TTTS cases undergoing SLPCV between July 2003 and May 2013, evaluating procedural details, delivery and perinatal outcomes. The majority of cases were Stage III at SLPCV (56.9%), although proportion of Stage II SLPCV increased over time (P = 0.03). Survival to hospital discharge of at least one baby was 85.6% and dual survival was 52.5%. Median gestational age at delivery was 32.6 weeks (IQR 29.0-35.0 weeks) with a median of 11.4 weeks (IQR 8.3-14.7) from laser to delivery. Median birthweight was 1792 g (IQR 1288-2233 g), with 75% of babies admitted to the nursery, predominantly secondary to prematurity. Immediate SLPCV complications were in utero fetal demise <1 week postprocedure in 27 fetuses (19.6%) and/or ruptured membranes <1 week postprocedure in 9 fetuses (6.6%). This Australian series shows that local outcomes after SLPCV for stages II-IV TTTS remain equal to the international published literature and have remained stable after an initial learning curve. Women were more likely to be Stage II rather than III in the more recent years. However, this does not appear to be attributable to altered referral patterns.

Chorioamniotic membrane separation after fetoscopy in monochorionic twin pregnancy: incidence and impact on perinatal outcome.

To evaluate the incidence of chorioamniotic membrane separation (CMS) after fetoscopy in monochorionic diamniotic (MCDA) twins and its impact on pregnancy outcome. The study group comprised a consecutive series of 338 women with an MCDA pregnancy complicated by twin-twin transfusion syndrome (TTTS) or selective intrauterine growth restriction (sIUGR) treated with selective laser photocoagulation of communicating vessels (SLPCV) or cord occlusion (CO). Data obtained included cervical length, gestational age at procedure, type and duration of surgery and placental location. The incidence of CMS, the rates of miscarriage and preterm prelabor rupture of membranes (PPROM), gestational age at delivery and neonatal survival were recorded. Of the study population of MCDA pregnancies, 270 (79.9%) had TTTS and 68 (20.1%) had sIUGR. SLPCV was performed in 252 (74.6%) cases and CO in 86 (25.4%). Postoperative CMS was observed in 70 (20.7%) cases. Patients with CMS had higher rates of miscarriage (14.3% vs 7.1%; P = 0.049), PPROM before 32 weeks (43.3% vs 13.7%; P < 0.001) and preterm delivery before 32 weeks (53.3% vs 26.1%; P < 0.001) and a lower rate of neonatal survival of at least one twin (81.7% vs 93.6%; P = 0.003). Multivariate analysis showed that gestational age at surgery was the only independent predictor, with the highest proportion of CMS occurring in cases that underwent surgery before 18 weeks' gestation (odds ratio, 2.941 (95% CI, 1.640-5.275); P < 0.001). There was no influence of cervical length, placental location, duration of surgery or type of surgery on the risk of CMS. CMS complicated one-fifth of all MCDA pregnancies that underwent fetoscopy. It appeared to be more common in those who underwent surgery before 18 weeks' gestation and was associated with poorer outcomes. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

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.

Ultrasound Assessment and Surgical Treatment of Twin-Twin Transfusion Syndrome

ABSTRACT The ultrasound diagnosis, management and treatment of twintwin transfusion syndrome (TTTS) have had a remarkable number of positive developments in the last 20 years. Together, they have resulted in TTTS being the most common condition seen and treated in fetal therapy centers today. This chapter discusses the basic ultrasound assessment of TTTS patients in a step-by-step fashion, to provide a structure to the sonographic examination. This includes review of the diagnostic criteria, the sonographic assessment of disease severity and preoperative ultrasound assessment. The chapter also reviews the rationale for, as well as the fundamental laser technique and its variations, including the nonselective technique, selective laser photocoagulation of communicating vessels (SLPCV), sequential selective laser photocoagulation of the communicating vessels (SQLPCV) and the ‘Solomon’ technique, and provides potential explanations for the outcome differences of each technique. Future developments in terms of surgical technique and long-term outcome studies are also discussed. How to cite this article Quintero RA, Kontopoulos EV. Ultrasound Assessment and Surgical Treatment of Twin-Twin Transfusion Syndrome. Donald School J Ultrasound Obstet Gynecol 2013;7(4):415-425.

Fetoscopic Laser Therapy for Twin-Twin Transfusion Syndrome

Ever since the first randomized, controlled trial revealed that fetoscopic laser photocoagulation achieved better outcomes than serial amnio-drainage for all stages of twin-twin transfusion syndrome (TTTS) before 26 weeks, many centers have launched their fetoscopic laser therapy program for TTTS. Initially the nonselective method of laser therapy was applied, using the dividing membrane as a landmark to coagulate the placenta vessels, but currently selective methods (selective laser photocoagulation of communicating vessels (SLPCV), sequential SLPCV, and Solomon technique) have evolved to become the mainstream laser treatment modalities. Nevertheless, the nonselective method still has a role in difficult operations. Over the years, with regard to the prognoses of TTTS treated by laser, the attention has gradually shifted from survival rate to the neurological outcomes. The incidence of severe neurodevelopmetal delay remains considerably high in survivors of TTTS treated by FLP, which some reports cited ranging from 6 % to 18 %; learning curve effect exists, affecting both the survival rate and neurological outcomes of TTTS treated by laser. Because more, yet smaller and less-experienced, centers are being set up worldwide, the purpose of this manuscript is to review the basic knowledge and update information about the laser therapy for TTTS.

409: Timing of intrauterine fetal demise (IUFD) following laser surgery for twin-twin transfusion syndrome (TTTS)

The purpose of this study was to describe the timing of post-operative IUFD following fetoscopic selective laser photocoagulation of communicating vessels (SLPCV) for TTTS, to allow for modification of counseling during the post-operative period.

Stage-based outcomes of 682 consecutive cases of twin–twin transfusion syndrome treated with laser surgery: the USFetus experience

We sought to describe stage-specific perinatal outcomes after selective laser photocoagulation of communicating vessels (SLPCV) for twin-twin transfusion syndrome. Patients with twin-twin transfusion syndrome underwent SLPCV preferentially using sequential vs standard laser technique. Patient characteristics and outcome data were examined by Quintero stage. Of 682 consecutive women studied, the Quintero stage distribution was: 114 stage I (17%), 177 stage II (26%), 328 stage III (48%), and 63 stage IV (9%). Perinatal survival of at least 1 twin did not differ according to stage (I-92%, II-93%, III-88%, IV-92%; P = .30). However, dual twin survival differed by stage (I-79%, II-76%, III-59%, IV-68%; P < .01), primarily because stage III pregnancies were associated with decreased donor twin survival (P < .01). Sequential SLPCV was associated with improved donor survival, independent of stage (odds ratio, 1.67; 95% confidence interval, 1.16-2.40; P < .01). Stage-specific perinatal outcomes after laser therapy may assist physicians in patient counseling and in planning future studies.

Triplets with feto-fetal transfusion syndrome treated with laser ablation: The USFetus experience

Objective. We sought to assess outcomes of triplets with feto-fetal transfusion syndrome (FFTS) treated with selective laser photocoagulation of communicating vessels (SLPCV).Study design. All twins and triplets with FFTS treated with SLPCV were analyzed. Triplets were classified as dichorionic–triamniotic (D/T) or monochorionic–triamniotic (M/T). In M/T triplets, SLPCV between FFTS affected recipient–donor pairs was performed first (step 1); SLPCV of remaining vascular communications was then attempted (step 2).Results. Forty-six of 692 (6.7%) gestations with FFTS treated with SLPCV were triplets; 40 (87%) were D/T, 6 (13%) were M/T. Overall perinatal survivorship in triplets versus twins were not different (73.9% vs. 75.1%, p = 0.757). SLPCV was achieved in 93% of D/T triplets. In the M/T triplets, step 1 was successful in all cases, and step 2 in half of cases. The D/T group delivered later in gestation than the M/T group (31.6 vs. 27.0 weeks, p = 0.049); no difference in overall perinatal survival was detected (75.8% vs. 61.1%, p = 0.248).Conclusion. Overall perinatal survival of triplets and twins with FFTS treated via SLPCV is similar. Significant surgical challenges were posed by monochorionic versus dichorionic triplets. Further studies of monochorionic triplets are required to ascertain perinatal survival post-SLPCV in this subset of triplets.

Amniopatch as a Treatment for Rupture of Membranes following Laser Surgery for Twin-Twin Transfusion Syndrome

Objective: The risk of iatrogenic rupture of membranes (IROM) is 5–30% after operative fetoscopy. The aim of this study was to describe outcomes of patients with IROM following selective laser photocoagulation of communicating vessels (SLPCV) for twin-twin transfusion syndrome (TTTS) who were subsequently treated with amniopatch therapy. Methods: A review of patients who underwent treatment for mid-trimester TTTS between March 2006 and February 2008 with IROM within 7 days of SLPCV was performed. IROM patients without evidence of preterm labor or chorioamnionitis were offered expectant management, pregnancy termination, or amniopatch therapy. Results: Ninety-three patients were treated with SLPCV, of which three (3.2%) had IROM within 7 days. All three opted for amniopatch therapy which was performed at 18 2/7, 23 1/7, and 22 6/7 weeks’ gestation in patients 1, 2 and 3, respectively. In patients 1 and 2, amniopatch therapy sealed membranes within 7 days. A second amniopatch was required for patient 3 before IROM resolved. Gestational ages at delivery were 38 2/7, 37 5/7 and 30 2/7 weeks, respectively. Conclusion: Amniopatch is a viable treatment option for iatrogenic ROM following SLPCV.

Triplets with feto-fetal transfusion syndrome treated with laser ablation: The USFetus experience

We sought to assess outcomes of triplets with feto-fetal transfusion syndrome (FFTS) treated with selective laser photocoagulation of communicating vessels (SLPCV). All twins and triplets with FFTS treated with SLPCV were analyzed. Triplets were classified as dichorionic-triamniotic (D/T) or monochorionic-triamniotic (M/T). In M/T triplets, SLPCV between FFTS affected recipient-donor pairs was performed first (step 1); SLPCV of remaining vascular communications was then attempted (step 2). Forty-six of 692 (6.7%) gestations with FFTS treated with SLPCV were triplets; 40 (87%) were D/T, 6 (13%) were M/T. Overall perinatal survivorship in triplets versus twins were not different (73.9% vs. 75.1%, p = 0.757). SLPCV was achieved in 93% of D/T triplets. In the M/T triplets, step 1 was successful in all cases, and step 2 in half of cases. The D/T group delivered later in gestation than the M/T group (31.6 vs. 27.0 weeks, p = 0.049); no difference in overall perinatal survival was detected (75.8% vs. 61.1%, p = 0.248). Overall perinatal survival of triplets and twins with FFTS treated via SLPCV is similar. Significant surgical challenges were posed by monochorionic versus dichorionic triplets. Further studies of monochorionic triplets are required to ascertain perinatal survival post-SLPCV in this subset of triplets.

645: Triplets with feto-fetal transfusion syndrome treated with laser ablation: A multicenter study

Selective laser photocoagulation of communicating vessels (SLPCV) in triplet gestations complicated by feto-fetal transfusion syndrome (FFTS) poses unique challenges. We sought to investigate survival of triplets with FFTS treated with SLPCV according to chorionicity, and to compare overall survival rates with twins. All twin and triplet gestations with FFTS treated with SLPCV in Tampa (USF) and Los Angeles (USC) were included in the analysis. Overall survival rate was defined as total number of 30-day survivors divided by total number of fetuses. Statistical analysis was performed via Fisher′s exact test and chi-square with Yates correction. 47 of 735 (6.4%) gestations with FFTS treated with SLPCV were triplets. Of the 47 triplets (40 at USF, 7 at USC), 39 (83%) were dichorionic-triamniotic (D/T) and 8 (17%) were monochorionic-triamniotic (M/T). The triplet survival rates according to fetal status were 57.4% for the donor, 74.5% for the recipient, and 89.4% for the “singleton”. The overall survival rate in the D/T group was 76.1% (89/117), which was not statistically different from the M/T group (62.5%, 15/24, p=0.262). None of the triplets had persistent or reversed FFTS post SLPCV. The overall survival rate of twins (73.0%, 1005/1376) was similar to triplets (73.8%, 104/141, p=0.93). Despite the significant surgical challenges posed by triplets with FFTS treated with SLPCV, no significant differences in overall survival rates were identified according to chorionicity and as compared to twins.

General vs local anesthesia for the percutaneous laser treatment of twin-twin transfusion syndrome

The purpose of this study was to review our anesthetic experience in selective laser photocoagulation of communicating vessels (SLPCV) to treat twin-twin transfusion syndrome (TTTS). A total of 266 consecutive eligible patients were studied. Twenty-seven patients (10%) underwent general anesthesia (GenA), 100 (38%) received total intravenous anesthesia (TIVA), and 139 (52%) received local anesthesia/conscious sedation (LocA). Maternal-fetal hemodynamic fluctuations were compared between groups. Maternal blood pressure decreased significantly in all 3 groups during surgery (P < .0001) but was more evident in the GenA and TIVA groups (P < .0001). Maternal heart rate varied significantly in GenA (P = .02) but was constant in LocA and TIVA. There were no significant differences in fetal heart rate changes between the groups. Intraamniotic bleeding occurred more frequently with GenA and TIVA than LocA(P < .0001). Local anesthesia is the safest anesthetic technique for SLPCV in TTTS patients.

516: Perinatal survival after third-generation laser therapy for twin-twin transfusion syndrome

There have been conflicting reports regarding perinatal outcome after selective laser photocoagulation of communicating vessels (SLPCV) for the treatment of twin-twin transfusion syndrome (TTTS). The aim of this study was to assess perinatal outcome in TTTS cases treated by third-generation SLPCV.

181: Sonographic assessment of suspected fetal anemia in the surviving twin after demise of the co-twin post-selective laser photocoagulation in twin-twin transfusion syndrome

Single intrauterine fetal demise (SIUFD), reported in up to 40% of patients after laser surgery for twin-twin transfusion syndrome (TTTS), has been associated with anemia of the surviving twin. Patent vascular anastomoses have been noted in up to 22% of these cases. The purpose of this study was to assess the incidence of de novo suspected fetal anemia (SFAdn) relative to SIUFD in TTTS patients treated with selective laser photocoagulation of communicating vessels (SLPCV).

692: Amniopatch as a treatment for rupture of membranes following laser surgery for twin-twin transfusion syndrome

The risk of pre- or periviable premature rupture of membranes (PPROM) is approximately 5 to 8% after operative fetoscopy. The aim of this study was to describe the outcomes of patients with PPROM following selective laser photocoagulation of communicating vessels (SLPCV) for twin-twin transfusion syndrome (TTTS).

OC116: Trocar‐assisted selective laser photocoagulation of communicating vessels

Objectives: Selective laser photocoagulation of communicating vessels (SLPCV) for twin–twin transfusion syndrome (TTTS) in patients with an anterior (ANT) placenta is known to be technically more challenging than in patients with posterior (POST) placentas. We describe a new trocar-assisted (TA) technique to address this issue. Methods: Four surgical techniques were used for SLPCV in ANT placentas: standard, rigid scope; flexible scope; side-firing, twoport; and TA, whereby the anastomoses were lasered from within the trocar sheath after identification with an angled diagnostic endoscope. The protocol was approved by the Institutional Review Board and all patients signed informed consent. Results: SLPCV was performed in 269 patients from February 2003 to May 2005, of which 88 (47.6%) had ANT placentas. Only 7/88 (7.9%) patients with ANT placentas were treated with a flexible scope or a two-port technique and neither of these techniques was used after November 2003. Perinatal survival was independent of placental location (89.7% vs. 85.2%, POST vs. ANT placentas) or ANT placenta techniques. Gestational age at delivery (median 33.1 (range, 17.6–39.4) weeks), and incidence of premature rupture of membranes within 21 days of surgery, was no different between techniques in patients with ANT. However, operating time was significantly less in the TA group (P < 0.05). In 50/88 patients with ANT placentas available for analysis, only one had patent anastomoses in the TA group (2.9%), compared to none in the other techniques (P = 0.7). Conclusions: Laser treatment of TTTS patients with an ANT placenta that requires more than a simple rigid endoscope can be effectively achieved with a TA technique. TA allows orthogonalization of the angle of fire, eliminating the need for a two-port or flexible endoscope technique. TA is also useful in exposing the entire vessel wall in patients with POST placentas with a tangential angle of entry.