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OBJECTIVE Despite improved perinatal survival following fetoscopic laser surgery (FLS) for twin twin transfusion syndrome (TTTS), prematurity remains an important contributor to perinatal mortality and morbidity. The objective of the study was to identify risk factors for complicated preterm delivery after FLS. STUDY DESIGN Retrospective cohort study of prospectively collected data on maternal/fetal demographics and pre-operative, operative and post-operative variables of 459 patients treated in 3 U.S. fetal centers. Multivariate linear regression was performed to identify significant risk factors associated with preterm delivery, which was cross-validated using K-fold method. Multivariate logistic regression was performed to identify risk factors for early vs. late preterm delivery based on median gestational age at delivery of 32 weeks. RESULTS There were significant differences in case selection and outcomes between the centers. After controlling for the center of surgery, a multivariate analysis indicated a lower maternal age at procedure, history of previous prematurity, shortened cervical length, use of amnioinfusion, 12 Fr cannula diameter, lack of a collagen plug placement and iatrogenic preterm premature rupture of membranes (iPPROM) were significantly associated with a lower gestational age at delivery. CONCLUSION Specific fetal/maternal and operative variables are associated with preterm delivery after FLS for the treatment of TTTS. Further studies to modify some of these variables may decrease the perinatal morbidity after laser therapy.

The ductus venosus has a central role in the distribution of highly oxygenated umbilical venous blood to the heart. Its waveform is related to the pressurevolume changes in the cardiac atria and it is therefore important in the monitoring of any fetal condition that may affect forward cardiac function. The cardiovascular parameters that can influence forward cardiac function include afterload, myocardial performance and preload. Decreased forward flow during atrial systole (a-wave) is the most sensitive and ubiquitous finding when any of these parameters is affected. In contrast, decreased forward velocities during end-systolic relaxation (v-wave) are more specifically related to myocardial performance. The ductus venosus pulsatility index alone does not accurately reflect cardiac function, and in cases of suspected fetal cardiac dysfunction, echocardiography is required to identify the underlying mechanism. The role of ductus venosus Doppler in the assessment of fetal growth restriction, supraventricular tachycardia, fetal hydrops, complicated monochorionic twins and congenital heart disease is discussed with these considerations in mind.Abbreviations: AV, atrio-ventricular; CHD, congenital heart disease; DV, ductus venosus; FGR, fetal growth restriction; PIV, pulsatility index for veins; SVT, supraventricular tachycardia; TTTS, twin-to-twin transfusion syndrome. The central role of ductus venosus in fetal cardiovascular assessmentDoppler examination of the fetal venous circulation was introduced into perinatal medicine over 25 years ago to extend cardiovascular functional assessment beyond the capabilities of arterial Doppler. All central and precordial venous vessels share the same flow pattern of forward flow in ventricular systole and diastole and a temporary decrease in forward flow during end-ventricular systole and atrial systole. However, the ductus venosus (DV) has several important characteristics that favor its widespread use in fetal medicine. It is a short vessel with a relatively fixed position, allowing for standardization of the Key messageThe ductus venosus waveform reflects the pressurevolume changes in the heart. Despite the limited specificity of the ductus venosus waveform, its correlation with cardiac forward function makes it of central importance in assessing the overall severity of fetal cardiovascular pathology. Ductus venosus Doppler study has a critical role in directing the clinical management of fetuses at risk of cardiovascular deterioration.ª

Women who develop preeclampsia while taking aspirin prophylaxis are more likely to have elevated first-trimester blood pressures. Conversely, first-trimester normotension is associated with a reduced risk of preeclampsia.