OBJECTIVE:To evaluate the impact of chorionicity on the perinatal outcomes of twin pregnancies complicated by twin-twin transfusion syndrome (TTS) or selective intrauterine growth restriction (sIUGR). METHOD:Pregnancies with 127 monochorionic (MC) and 109 dichorionic (DC) twins were followed up, and TTS and sIUGR incidence as well as morbidity and mortality were evaluated. RESULTS:The incidence of intrauterine fetal death was higher in MC than in DC pregnancies (6.5% vs. 1%), and higher in MC pregnancies complicated by TTS (5 deaths in 10 pregnancies [50%]) or sIUGR (2 in 9 [22%]). The incidence of sIUGR was similar in MC and DC pregnancies (7% vs. 5%), and the incidence of TTS was 8% in MC pregnancies (95% confidence interval, 3.2-12.8). Neonatal neurological and respiratory morbidity was higher among MC twins, and the increase in neonatal complications was linked to TTS and sIUGR. Uncomplicated MC and DC pregnancies had similar perinatal outcomes. CONCLUSION:The incidence of neonatal complications was higher in MC twins born of pregnancies complicated by TTS or sIUGR. Although the incidence of sIUGR was similar in MC and DC pregnancies, there was a trend towards worse outcomes in MC pregnancies affected by sIUGR.

Objective To estimate changes in umbilical blood flow (UBF) and Doppler indices in pregnancies complicated by twin-to-twin transfusion syndrome (TTS) treated with either laser therapy or amniodrainage, and to evaluate the influence of the presence of hemodynamic deterioration prior to therapy, as determined by the Quintero stages of severity.Methods Forty-eight cases of TTS were included, and further classified into severity Stages I or II (absence of critically abnormal Dopplers (CAD), n = 22) and Stages III or, IV (presence of CAD or hydrops fetalis, n = 26). In,Stages I-II, 14 cases were treated with laser and eight with amniodrainage, and in Stages III-IV, 17 were treated with laser and nine with amniodrainage. Differences in the UBF, umbilical artery pulstility index (UA-PI) and ductus venosus pulsatility index (D V-PI) were estimated for both groups of severity before and after both treatments. Eleven normal monochorionic pregnancies were evaluated as controls.Results In recipients, UBF was significantly higher with respect to controls regardless of the stage, while donors had a significant decrease in UBF, but only in Stages III-IV. After laser treatment no changes were observed in fetuses in Stages I-II. In Stages III-IV, recipients showed a significant reduction in the DV-PI (mean DV-PI 1.31 +/- 0.18 vs. 1.05 +/- 0.22; P = 0.005) whereas donors showed a significant increase in the UBF (mean UBF 134 +/- 36 mL/min vs. 195 +/- 25 mL/min; P < 0.001) and in the DV-PI (mean DV-PI 0.99 +/- 0.26 vs. 1.36 +/- 0.42; P = 0.002), and a reduction in the UA-PI (mean UA-PI 1.86 +/- 0.41 vs. 1.58 +/- 0.30; P =.0.01). After amniodrainage only donor fetuses in Stages III-IV showed an increase in UA-PI (mean UA-PI 1.54 +/- 0.35 vs. 1.72 +/- 0.40; P = 0.015). No other changes were observed in any of the parameters studied.Conclusion Laser therapy induces consistent hemodynamic variations in TTS mainly manifested in Stages III-IV. Copyright (c) 2006 ISUOG. Published by John Wiley & Sons, Ltd.

Evaluar la incidencia y la relevancia clínica del flujo diastólico intermitente en el Doppler de arteria umbilical en la gestación monocorial. Estudio prospectivo que incluyó 3 grupos de gemelos monocoriales: grupo I, una cohorte de gemelos monocoriales controlados con ecografía cada 15 días desde el primer trimestre (n = 80); grupo II, retardo de crecimiento intrauterino selectivo (n = 40), y grupo III, síndrome de transfusión fetofetal grave (n = 50). Se registró la presencia y persistencia en el tiempo de flujo diastólico ausente y/o revertido intermitente en el Doppler de arteria umbilical. Se examinaron las placentas, se registró la presencia de anastomosis arterioarteriales grandes (> 2 mm) y se calculó el reparto placentario. Los resultados perinatales se obtuvieron en todos los casos. Se observó flujo diastólico intermitente en el 5% (4/80) de los casos del grupo I, en el 45% (18/40) del grupo II y en el 2% (1/50) del grupo III (p < 0,0001, grupo II frente a I y III). Se identificaron anastomosis arterioarteriales grandes en todos los casos examinados con flujo intermitente (18/18) y en el 3,6% (4/112) de los casos sin él. No hubo mortalidad fetal intraútero en el grupo I y en los fetos del grupo II sin flujo intermitente. En los casos del grupo II con flujo diastólico intermitente, la mortalidad intraútero global fue de 19,4%. El flujo diastólico intermitente debe considerarse como un signo característico de los gemelos monocoriales, y parece ser la expresión de la existencia de anastomosis arterioarteriales grandes. Su incidencia está significativamente aumentada en el contexto del retraso de crecimiento intrauterino selectivo, e indica un mal pronóstico perinatal en esos casos. To evaluate the incidence and clinical relevance of intermittent diastolic flow on umbilical artery Doppler in monochorionic twin pregnancies. We performed a prospective study that included 3 groups of monochorionic pregnancies: group I: a cohort of monochorionic pregnancies with ultrasonographic follow-up every 15 days from the first trimester (n = 80); group II: monochorionic twins with selective intrauterine growth retardation (n = 40), and group III: severe twin-twin transfusion syndrome (n = 50). The presence and persistence over time of intermittent absent and/or reverse diastolic flow on umbilical artery Doppler was recorded. Placentas were examined and placental sharing and the presence of large arterio-arterial anastomoses (> 2 mm) were assessed. Perinatal outcome was recorded in all cases. Intermittent diastolic flow was present in 5% (4/80) of pregnancies in group I, 45% (18/40) in group II and 2% (1/50) in group III (p < 0.0001, group II versus groups I and III). Large arterioarterial anastomoses were identified in all examined pregnancies with intermittent flow (18/18) and in 3.6% (4/112) of those without. The in utero mortality rate was 0% in group I and in group II fetuses without intermittent flow. However, intrauterine mortality was 19.4% in fetuses in group II with intermittent diastolic flow. Intermittent diastolic flow should be considered a characteristic sign of monochorionic pregnancy. This sign seems to result from the presence of large arterio-arterial anastomoses. The incidence of intermittent diastolic flow is significantly increased in the context of selective intrauterine growth retardation, indicating a poor perinatal outcome in these cases.

OBJECTIVE:This study was undertaken to determine whether laser thermocoagulation for twin-twin transfusion syndrome (TTTS) causes increased cell-free fetal DNA levels in maternal plasma, potentially as a result of placental injury. STUDY DESIGN:We enrolled 34 patients with twin pregnancies complicated by severe TTTS who underwent fetoscopic selective laser ablation of placental vascular anastomoses. Blood samples were drawn before and sequentially after the procedure. Fetal DNA in maternal plasma was quantified by polymerase chain reaction amplification of a Y-chromosome sequence. RESULTS:Compared with baseline, median elevations of fetal DNA levels were 0.8% at 30 minutes ( P = .32), 15.8% at 60 minutes ( P = .1), 179.5% at 24 hours ( P = .003), and 172.9% at 48 hours ( P = .003). Factors associated with increased fetal DNA levels at 24 hours after procedure included longer operation time, higher number of vessels ablated, and subsequent in utero fetal death ( P = .01, .04, and .04, respectively). CONCLUSIONS:Persistent elevation of fetal DNA levels in maternal plasma after laser ablation suggests that circulating fetal DNA could derive from placental injury. Plasma fetal DNA analysis may be an additional prognostic marker for fetal outcome after laser therapy.

To evaluate changes in the cardiac preload of monochorionic twins with twin-to-twin transfusion syndrome (TTTS), before and after laser coagulation of the communicating anastomosis (LPCA). A total of 22 pairs of monochorionic twin pregnancies affected with TTTS were evaluated. According to the Quintero staging system for severity, 12 were classified in stage I, 10 in stage II, 5 in stage III and 5 in stage IV. All were subjected to LPCA. Preload index in the inferior vena cava (IVCPLI), pulsatility index in the ductus venosus (DVPI) and tricuspid E/A waveform relationship (Tric E/A) were calculated with pulsed Doppler ultrasound in both twins one day before LPCA and 3 and 7 days later. Changes over time for recipient and donor twins and the differences between them were estimated and evaluated by analysis of variance (ANOVA). At the end of the studied period, the obtained values were compared with a control group of dichorionic twins at the same gestational age. Before LPCA, the recipient fetuses showed an increased DVPI and IVCPLI as compared with the donors. In contrast, 3 days after LPCA, the donor twins showed a higher DV PI and IVC PLI than the recipients. Seven days later, there were no differences between both. There were no differences in the Tric E/A but the same trend over time as the IVC and DV was observed. According to the Quintero grading system, all fetuses showed the same trend as described, however, only cases in stages III and IV showed significant differences. Seven days after LPCA; DVPI, IVCPLI and Tric E/A from monochorionic twin pregnancies were still higher than control dichorionic twins. After LPCA the donor twin transiently increases, and the recipient twin progressively decreases its preload cardiac volume. This adaptive response in the donor may explain post-laer transient hydropic signs occurring in part of these fetuses.

To determine if laser thermocoagulation for twin–twin transfusion syndrome (TTTS) causes increased cell-free fetal DNA levels in maternal plasma, potentially as a result from placental injury. 34 patients were enrolled with twin pregnancies complicated by severe TTTS who underwent fetoscopic selective laser ablation of placental vascular anastomoses. Blood samples were drawn prior to and sequentially after the procedure. Fetal DNA in maternal plasma was quantified by PCR amplification of a Y-chromosome sequence. Median elevations of fetal DNA levels compared to baseline were 0.8% at 30 minutes (P = 0.32), 15.8% at 60 minutes (P = 0.1), 179.5% at 24 hours (P = 0.003) and 172.9% at 48 hours (P = 0.003). Factors associated with increased fetal DNA levels at 24 hours post procedure included longer operation time, higher number of vessels ablated, and subsequent in utero fetal death (P = 0.01, 0.04, and 0.04, respectively). Persistent elevation of fetal DNA levels in maternal plasma following laser ablation supports the placenta as its tissue of origin. Plasma fetal DNA analysis may be an additional prognostic marker for fetal outcome after laser therapy.

Objective To evaluate the incidence and clinical relevance of intermittent absent and/or reversed diastolic flow on umbilical artery Doppler in different groups of monochorionic twin pregnancies.Methods This was a prospective study involving three groups of monochorionic pregnancies: Group 1: controls followed fortnightly from the first trimester (n = 80); Group 2: cases with selective intrauterine growth restriction (n = 40); and Group 3: cases with severe twin-twin transfusion syndrome (n = 50). The presence and persistence over time of intermittent absent and/or reversed end-diastolic flow on umbilical artery Doppler was recorded. Placentas were examined and placental sharing and the presence of large arterioarterial anastomoses (AAA) was assessed. Perinatal outcome was recorded in all cases.Results Intermittent absent and/or reversed diastolic flow was present in 5% (4/80) of cases in Group 1,45% (18/40) in Group 2 and 2% (1/50) in Group 3 (P < 0.0001, Group 2 vs. I and 3). Placental examination was performed in 76.4% (130/170) of cases and sharing was 58% for Group 1, 81% for Group 2 and 73% for Group 3 (P < 0.0001, Groups 2 and 3 vs. 1). Large AAA were identified in all examined cases with intermittent flow (18118) and in 3.6% (4/112) of those without. The in-utero mortality rate was 0% in Group I and in Group 2 fetuses without intermittent flow. However, it was 19.4% in Group 2 cases with intermittent diastolic flow.Conclusions Intermittent absent and/or reversed end-diastolic flow may be considered to be a characteristic sign of monochronic pregnancy, and seems to result from the existence of large AAA. Its incidence is significantly increased in the context of selective intrauterine growth restriction, indicating a high risk for poor pregnancy outcome in these cases. Copyright (C) 2004 ISUOG. Published by John Wiley Sons, Ltd.

Objective To assess the incidence of parenchymal lesions on early and late neonatal brain scans and its association with the presence or absence of intermittent absent or reversed end-diastolic umbilical artery flow velocity (A/REDV) in monochorionic twins complicated by selective intrauterine growth restriction (IUGR), as compared to dichorionic twins and monochorionic twins without selective IUGR. Methods This was a prospective cohort study involving 42 monochorionic twins diagnosed with selective IUGR and managed expectantly. The presence or absence of intermittent A/REDV was recorded in all cases. This study group was compared to dichorionic twins (n = 29) and monochorionic twins without selective IUGR (n = 32) delivered at 26-34 weeks during the study period. All infants underwent an early neonatal brain scan (at or before the fourth day of postnatal life) and at least one follow-up scan during the first 28 days of postnatal life. Perinatal outcome and the incidence of neurological damage were compared between the study groups. Results The incidence of intrauterine fetal death (IUD) and periventricular leukomalacia was significantly increased in monochorionic twins complicated with selective IUGR, as compared with the other study groups. Intermittent A/REDV was observed in 22/2 (52.4%) twin pairs, and was always present in the growth-restricted twin. The incidence of IUD (overall 9/44 (20.5%) vs. 0140, P < 0.001; smaller twin 6/22 (27.3%) vs. 0/20, P < 0.05) and parenchymal brain damage (overall 7/35 (20.0%) vs. 2/40 (5.0%), P = 0.07; larger twin 7/19 (36.8%) vs. 1/20 (5.0%), P < 0.05) was significantly higher in pregnancies with intermittent A/REDV than in those without intermittent A/REDV. Brain damage usually occurred in the larger twin, irrespective of whether the smaller twin was liveborn or not. Conclusions The presence of intermittent A/REDV in monochorionic twins with selective IUGR identifies a subgroup with an elevated risk of intrauterine demise of the smaller twin and neurological damage in the larger twin; this latter finding is not restricted to cases with IUD of the cotwin. Copyrigbt (C) 2004 ISUOG. Published by John Wiley & Sons, Ltd.

To determine if thermal/ischemic cotyledon injury following laser ablation in twin-twin transfusion syndrome (TTTS) causes increased cell-free fetal DNA (fDNA) levels in maternal plasma. We enrolled 34 women with twin pregnancies complicated by severe TTTS who underwent fetoscopic laser ablation of placental vascular anastomoses. Blood samples were drawn prior to and at intervals after the procedure. Fetal gender was ascertained by sonography, genetic amniocentesis, or at delivery. fDNA in maternal plasma was quantified by PCR amplification of a fetal Y-chromosome sequence. Fetal gender detection (30 males, 4 females) was 100% accurate. Using the paired t-test, mean fDNA levels were increased above baseline by 21% at 30 min (P = 0.22), 51% at 60 min (P = 0.02), 384% at 24 hrs (P<0.01), and 171% at 48 hrs (P<0.01). No correlation was found between the number of vessels coagulated, gestational age, or amount of amniotic fluid drained and the magnitude of fDNA elevation. Nine patients who had IUFD of 1 or both twins post procedure had a significantly higher fDNA increase (954%) at 24 hrs than those who delivered 2 liveborn infants (216%) (P = 0.04). Increase in fDNA levels following laser ablation supports its placental origin. Persistent elevation at 24 and 48 hrs suggests ongoing placental damage. A marked increase in fDNA above that expected at 24 hrs occurs in IUFD. Lack of correlation between the number of vessels coagulated and magnitude of fDNA elevation necessitates further studies to comprehend the dynamics of fDNA in the maternal circulation.

Evaluar los resultados perinatales en los primeros 50 casos de transfusión feto-fetal (TFF) tratados en España con coagulación fetoscópica láser de anastomosis placentarias Estudio prospectivo con 50 casos de TFF grave tratadas con láser. Se evaluó la supervivencia y la evolución neonatales, las complicaciones obstétricas, y la tasa de lesión neurológica neonatal (28 días) La edad gestacional media de tratamiento fue de 19,8 semanas (rango: 16,6–25,8). La supervivencia neonatal global fue del 72% (72/100), con un 86% (43/50) de casos con, al menos, un superviviente. Ocurrió rotura prematura de membranas en 9 pacientes (18%), tres de ellas (6%) precoces (menos de 32 semanas). La edad gestacional media de parto fue de 31,8 semanas (rango: 26,0-38,2), con un 94% (47/50) por encima de las 28 semanas. El peso medio fue de 1.840 g (rango: 640-3.390) para receptores y 1.415 g (rango: 390-2.250) en donantes. Se observó algún grado de lesión neurológica en el 5,5% (4/72) de los supervivientes Los resultados presentados se sitúan en el rango alto de lo previamente reportado por otros grupos. La coagulación fetoscópica láser permite ofrecer una alternativa terapéutica a una proporción importante de casos de TFF grave To evaluate perinatal outcome in the first 50 cases of severe twin-twin transfusion syndrome (TTS) treated in Spain with fetoscopic laser coagulation of the placental anastomoses We performed a prospective study of 50 cases of severe TTS treated with laser therapy. The main outcome measures were perinatal outcome, obstetric complications and the rate of neurological damage at 28 days The mean gestational age at therapy was 19.8 weeks (range: 16.6–25.8). Overall neonatal survival was 72% (72/100) and at least one twin survived in 86% (43/50) of the pregnancies. Premature rupture of membranes occurred in nine patients (18%). In three of these patients (6%), rupture developed before 32 weeks. The mean gestational age at delivery was 31.8 weeks (26.0- 38.2), and 94% (47/50) of the women delivered after 28 weeks. The mean birthweight was 1840 grams (range: 640-3390) in recipients and 1415 grams (range 390-2250) in donors. Some degree of neurological damage was observed in 5.5% (4/72) of survivors The results of this series are in the upper range of previously reported results. Fetoscopic laser coagulation is an effective treatment in a considerable proportion of pregnancies complicated with severe TTS