Fetal Mild Hydronephrosis and Chromosomal Defects: Relation to Maternal Age and Gestation

Abstract

The presence of multiple ultrasonographic abnormalities is associated with a significantly increased risk of chromosomal defects, while for isolated abnormalities, the association is less clear. In a study of 1,177 fetuses with mild hydronephrosis at 16-26 weeks of gestation, the fetal karyotype was abnormal in 86 (7.3%) of the cases and the most common chromosomal defects were trisomies 21,18 and 13. The frequency of chromosomal defects increased with the number of additional abnormalities and for each chromosomal defect there was a characteristic pattern of associated abnormalities. However, in the 805 fetuses with apparently isolated hydronephrosis there were 5 (0.62%) with trisomy 21. On the basis of the maternal age and gestational age distribution of the population the expected frequency of trisomy 21 was 0.40%, which was not significantly different from the observed (0.62%). To demonstrate that such a difference is significant, it would be necessary to investigate at least 1 million pregnancies. In the meantime, parents could be counselled that the presence of mild hydronephrosis does not increase significantly the risk that the fetus has trisomy 21. Alternatively, the risk is 1.6 times higher than the maternal age and gestational age-related risk.

Sonographic markers of fetal trisomies: second trimester.

“…Our own analysis is consistent with this risk, although this risk may not be increased when pyelectasis is isolated. The lack of association as an isolated finding has also been suggested by other studies, 102,103 although one center has shown an association as an isolated finding. 104 …”

Mild renal pyelectasis in the second trimester: determination of cut‐off levels for postnatal referral

“…In our high‐risk population, associated anomalies were seen in 8% of cases. In other studies16–18 this percentage varied between 3.9% and 31.6%. The relatively high percentage of associated anomalies in the present study is likely to be due to the fact that a high‐risk population was investigated.…”

Preventing Crystallization of Phospholipids in Monolayers: A New Approach to Lung‐Surfactant Therapy

“…To date, the association between isolated pyelectasis is unresolved. While some studies reported an association (Corteville et al , 1992; Nicolaides et al , 1992; Wickstrom et al , 1996a, 1996b; Chudleigh et al , 2001) when pyelectasis occurred in the absence of other congenital malformations, others have found no such association (Snijders et al , 1995a; Vintzileos and Egan 1995; Nyberg et al , 2001; Havutcu et al , 2002; Coco and Jeanty 2005). Reported likelihood ratios have also varied among previous published studies.…”