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Objective To evaluate the usefulness of transvaginal ultrasonography in the determination of the risk of preterm delivery and chorioamnionitis in pregnancies affected by preterm premature rupture of membranes preterm premature rupture of membranes. Design One hundred and one singleton pregnancies with preterm premature rupture of membranes were included in this prospective study over a 3-year period. Patients underwent cervical length measurement by transvaginal ultrasonography at admission and thereafter, in the absence of chorioamnionitis, were managed expectantly. Results The median time interval between admission and delivery (latency period) was 48 h. A cervical length of less than 20 mm was associated with a significant risk of early delivery (mean latency period was 59.44 ± 159.93 h vs. 240.94 ± 364.67; P < 0.05). There was no relation between cervical length and occurrence of chorioamnionitis or neonatal sepsis. Conclusions These data suggest that the use of transvaginal ultrasonography for cervical length measurement during preterm premature rupture of membranes may predict an early delivery but cannot anticipate the risk of chorioamnionitis or neonatal sepsis.

This study examines the value of assessing inter-twin membrane folding in monochorionic twin pregnancies in the prediction of twin-to-twin transfusion syndrome. In 83 monochorionic twin pregnancies ultrasound scans were carried out at 10-14, 15-17 and 19-21 weeks to investigate folding of the inter-twin membrane as an early sonographic feature of inter-twin discrepancy in amniotic fluid volume. There were 23 (28%) cases of membrane folding, which was first observed in one case at 10-14 weeks, in 21 cases at 15-17 weeks and in another case at 24 weeks. In 12 (52%) of the 23 cases the pregnancy progressed to severe twin-to-twin transfusion syndrome and 10 of these were treated by endoscopic laser coagulation of the placental vascular anastomoses. In the other 11 cases there was a moderate syndrome with large discrepancies in amniotic fluid volume and fetal size, persisting throughout pregnancy. In the severe group, five pregnancies resulted in live birth of both babies, three in live birth of one and intrauterine death of the other twin and in four cases there were no survivors. In the moderate group, all babies survived and the inter-twin disparity in birth weight was more than 20%. Similarly, all 60 pregnancies with no membrane folding resulted in live births. In all three groups there was an increase in inter-twin disparity in fetal size with gestation and the greatest inter-twin disparities were in those with moderate twin-to-twin transfusion syndrome from as early as the 10-14 week scan. These findings demonstrate that folding of the inter-twin membrane occurs in about one-quarter of monochorionic twins and in about half of these there is subsequent development of severe twin-to-twin transfusion syndrome.

The study examines a possible association between increased nuchal translucency thickness at 10-14 weeks of gestation in monochorionic twin pregnancies and the subsequent development of severe twin-to-twin transfusion syndrome (TTS). In 132 monochorionic twin pregnancies, including 16 that developed severe TTS at 15-22 weeks of gestation and 116 that did not develop TTS, crown-rump length, nuchal translucency thickness and fetal heart rate were measured at 10-14 weeks. In those that developed severe TTS, the prevalence of nuchal translucency thickness above the 95th centile of the normal range and the intertwin difference in nuchal translucency thickness and fetal heart rate were significantly higher than in the non-TTS group; there were no significant differences between the groups in the inter-twin difference in crown-rump length. For fetal nuchal translucency above the 95th centile, the positive and negative predictive values for the development of TTS were 38% and 91%, respectively; the likelihood ratios of nuchal translucency above or below the 95th centile for the development of severe TTS were 4.4 (1.8-9.7) and 0.7 (0.4-0.9), respectively. These findings demonstrate that the underlying hemodynamic changes associated with TTS may manifest as increased fetal nuchal translucency thickness at 10-14 weeks of gestation.