Introduction: Twin reversed arterial perfusion (TRAP) is a rare condition in monozygotic multiple gestations, caused by the formation of large arterio-arterial anastomoses. Only few serial ultrasound observations are reported, showing the delayed development in the recipient twin. Case: A monochorionic monoamniotic twin pregnancy with discordant growth was diagnosed at 11 weeks and 4 days in a 28-year-old primigravida. The smaller twin, who first appeared as an amorphic mass, showed growth and developed a clearly recognizable spine and lower limbs in further ultrasound examinations. Conclusion: This case illustrates that developmental arrest in acardiac fetuses does not affect the total organism at one time, but that some embryonic fields keep on developing into macroscopically recognizable structures.

Objective: To validate the clinical impression that absent enddiastolic flow (AEDF) in the umbilical artery (UA) in monochorionic

Methods: Retrospective review of cases. Information was obtained by reviewing the ultrasound reports and medical records, as well as from the referring obstetricians. Results: Five third-trimester fetuses were diagnosed as having a congenital dacryocystocele at a median gestational age of 31 weeks (range, 26-33). Only one case was bilateral. In all cases the dacryocystocele presented as an anechoic mass in relation to the inferiomedial aspect of the fetal eye. Color-Doppler ultrasound confirmed absent blood flow signals within the mass in all cases. The mass diameter ranged from 7-12 mm. There were no other associated findings. 3D ultrasound, carried out in the latest two cases, clearly depicted the anomaly as well as the intranasal projection. Surface-rendering imaging showed swelling below the medial canthal area in both cases. Resolution in utero occurred in two cases, one bilateral and another unilateral. The prenatal diagnosis was confirmed at birth in the other three cases and there were no long-term sequelae associated with this finding. Conclusions: Prenatal diagnosis of dacryocystocele is straightforward. Although several differential diagnoses might be considered, the prenatal findings in this condition are typical due to its location and ultrasound appearance. 3D ultrasound was useful to depict clearly the anomaly and allowed parental reassurance regarding the benign prognosis and absence of significant distortion of the fetal face. We also noted that, in a significant number of cases, there was spontaneous resolution in utero. If the mass persists until delivery, ophthalmologic consultation is warranted.

Objective: To analyse the predictive value of different cervical length cut-offs for spontaneous preterm delivery < 32 and < 34 weeks in twin pregnancies. Methods: Transvaginal cervical ultrasound examinations were performed in 106 twin pregnancies between 20 and 26.6 weeks (January 2001 to January 2003). Sensitivity, specificity and predictive values of cervical length (20, 25 mm) at 20-24 and 24.1-26.6 weeks for the prediction of spontaneous preterm birth < 32 and < 34 weeks were calculated. Twin gestations electively delivered preterm because of maternal or fetal indications were excluded from this analysis. Results: The median gestational age at delivery was 35 weeks (range 23.2-39.3). Cerclage was performed in 12 patients with cervical length 25 mm or prolapse of membranes at a median gestational age of 23 weeks (range 20.5-26.2). The rate of spontaneous delivery < 32 and < 34 weeks was 8.4% (9/106) and 13.2% (14/106) respectively. In the group of patients evaluated at 20-24 weeks, 7/85 (8.2%) women delivered spontaneously < 32 weeks and 9/85 (10.6%) < 34 weeks; in the group of patients evaluated at 24.2-26.6 weeks, 2/66 (3%) delivered spontaneously < 32 weeks and 7/66 (10.6%) < 34 weeks. Cervical length at 20-24 weeks with a cut-off value 20 mm had specificities of 99% and 99%, sensitivities of 43% and 33%, negative predictive values of 95% and 92%, positive predictive values of 75% and 75% for delivery < 32 and < 34 weeks, respectively. Cervical length at 20-24 weeks with a cut-off value 25 mm had specificities of 95% and 94%, sensitivities of 43% and 33%, negative predictive values of 95% and 91%, positive predictive values of 43% and 43% for delivery < 32 and < 34 weeks, respectively. Conclusions: In twin gestations a cervical length 20 mm measured at 20-24 weeks is the best cut-off to predict spontaneous preterm delivery. P370Comparing three different types of monitoring the cervix in triplet pregnancies: no screening versus single screening at 24 weeks versus longitudinal screening from 16 weeks onwards