Our results suggest that during the first trimester of normal pregnancy, active renin concentration in the plasma is increased and that renin is not the factor that limits angiotensin II synthesis. These results also confirm decreased activity of the renin-angiotensin-aldosterone system in preeclampsia. This could contribute to the diminished hemodynamic control observed in pregnant women developing preeclampsia.

The criteria for the detection of fetal pyelectasis are still controversial. Prenatal and postnatal data from 2,170 consecutive pregnant women who underwent at least one antenatal ultrasound scan were prospectively studied. Fetal pyelectasis was defined on the basis of a mean renal pelvis dimension > 5 or 10 mm before or after 28 weeks of gestation, respectively. Pyelectasis was detected in 95 (4.4%) fetuses. Eighty-nine among them were explored after birth. In 13 (13.7%) cases, an obstructive urinary tract abnormality, a severe vesicoureteral reflux, or a megaureter were diagnosed postnatally. In 29 (30.5%) cases, pyelectasis was confirmed postnatally, while complementary investigations ruled out an obstruction of the urinary tract. The incidence of urinary tract malformations was thus 0.60%, while the positive predictive value was 13.7%. We recommend to use a value not < 10 mm of the renal pelvis mean dimension beyond 28 weeks of gestation as a threshold for detection of fetal upper urinary tract obstruction, in the absence of ureteric and/or bladder dilation. Any value between 5 and 10 mm measured during the 2nd trimester of gestation should be confirmed by a second ultrasound examination performed during the 3rd trimester, before being considered pathological.

The prenatal diagnosis of pulmonary sequestration can usually be made by the third trimester of pregnancy, from the combination of an intrathoracic mass and indirect signs such as cardiac deviation, fetal hydrops, pleural effusion and polyhydramnios. We describe four cases in which pulmonary hyperechogenicity was detected before 26 weeks' gestation. In three cases the hyperechogenic mass was isolated. In all cases it had mostly regressed during the pregnancy. A review of the cases of isolated pulmonary sequestration that have been diagnosed during the antenatal period is presented. Antenatal evolution was found to be unpredictable regardless of the type or severity of the case at the first diagnosis. We propose a classification to define more clearly the optimal management of pulmonary sequestration.

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We report a case of sirenomelia of the symelia dipus type which is associated with complete situs inversus. Sirenomelia is difficult to diagnose prenatally because of a frequently associated oligohydramnios. Symelia dipus type adds to the difficulty of the diagnosis, since the bones of the thighs and legs are fully formed. In fact, a close examination of the cases of sirenomelia previously reported in the literature shows that a prenatal diagnosis was achieved only when the oligohydramnios was no more than moderate and/or the associated malformation was of apus or unipus type. We propose a systematic amnioinfusion when one suspects symelia unipus type. Finally, the pathogenesis of sirenomelia is discussed, as the presence of a complete situs inversus in the case reported here could illuminate the debate concerning the origin of the malformation.