The effect of a systemic arteriovenous fistula on the pulmonary arterial blood pressure in the fetal sheep

In order to investigate whether systemic arteriovenous fistula occurring during the fetal period could induce pulmonary hypertension at birth, a fistula was surgically created between the carotid artery and jugular vein of fetal lambs at 120 days' gestation. Mean pressures in the left pulmonary artery, aorta, atrium and ventricles were measured at birth in seven experimental animals and in five control animals. Mean left pulmonary pressure was significantly higher in the lambs with fistula as compared with the control group, suggesting that prenatal occurrence of systemic arteriovenous fistula may induce fetal pulmonary hypertension. The present study provides a new animal model that could be relevant for the study of mechanisms regulating pulmonary vascular tone in the perinatal period. Copyright © 2002 John Wiley & Sons, Ltd.     

Does a ‘notched’ nuchal translucency indicate Down syndrome fetuses or other adverse pregnancy outcome?

The aim of the present study was to assess the sonographic contour of the increased nuchal translucency (NT) and to correlate this with pregnancy outcome. Fifty sonographic images of fetuses with increased NT [>95th centile thickness of the normal range for crown–rump length (CRL) between 38 and 84 mm] were retrospectively assessed. In all the cases a complete pregnancy and even infancy follow-up (<36 months) was available. The NT appearances were subdivided into two forms: a ‘notched’ or ‘uniform’ appearance. The images were correlated with karyotype results [trisomy 21 (DS) vs euploid cases] and pregnancy outcome. Complicated outcomes were classified as being either DS fetuses, miscarriage or termination of pregnancy because of structural anomaly. Thus 30/35 (86%) of the euploid fetuses had a ‘uniformly’ increased NT, whereas 8/13 DS cases (62%) had a ‘notched’ appearance (Fisher's exact test, p=0.004). Additionally, 27/29 fetuses (93%) which had an uneventful pregnancy outcome had a ‘uniform’ increased NT, whereas 12/26 (57%) of the fetuses which had adverse pregnancy outcome had a ‘notched’ appearance of their NT (Fisher's exact test, p<0.001). Although it was not possible to correlate the sonographic data with post-evacuation microdissection findings, it is possible that a uniformly shaped, increased NT may be more representative of a developmental delay in a normal fetus. Conversely, a ‘notched’ nuchal surface may represent abnormal lymphatic or cardiovascular development more commonly seen in DS fetuses. Copyright © 2001 John Wiley & Sons, Ltd.