FETAL RENAL PYELECTASIS AND DOWN SYNDROME

Mild dilatation of the fetal renal pelvis (pyelectasis) is commonly seen in normal fetuses, but has a higher incidence amongst fetuses with Down syndrome.

• Benacerraf BR and co-workers 1990 (1).
• 25% fetuses with Down Syndrome had dilatation of the renal pelvis ³4mm(AP diameter)
• When fetal pyelectasis was present, the incidence of Down syndrome = 3.3%
• Crane and Gray 1991 (2).
• Pyelectasis in 3/16 fetuses with Down syndrome
• Corteville and co-workers 1992 (3).
• Incidence of pyelectasis among fetuses with Down syndrome = 17% versus 2% in normal controls.
• Wickstrom and co-workers (4).
• 3.9 fold increase in Down syndrome risk.
• 3.3 fold increase risk for all chromosomal abnormalities.
• Risk of trisomy 21 in isolated pyelectasis is less than 1:340 (3, 5-7), suggesting that fetal karyotyping in cases of isolated pyelectasis is not indicated.

REFERENCES

1. Benacerraf BR, Mandell J, Estroff JA et.al. Fetal pyelectasis, a possible association with Down syndrome. Obstet Gynecol 1990; 76:58-60
2. Crane JP, Gray DL. Sonographically measured nuchal skinfold thickness as a screening tool for Down syndrome: results of a prospective clinical trial. Obstet Gynecol 199; 77: 533-536
3. Corteville JE, Dicke JM, Crane JP. Fetal pyelectasis and Down syndrome, is genetic amniocentesis warranted? Obstet Gynecol 1992; 79:770-772
4. Wickstrom
5. Thompson MO, Thilaganathan B. Effect of screening for Down syndrome on the significance of isolated fetal hydronephrosis. Br J Obstet Gynaecol 1998;105:860-864.
6. Seeds JW. Borderline genitourinary tract abnormalities. Semin Ultrasound CT MR 1998;19:347-354.
7. Snijders RJ, Sebire NJ, Faria M et.al. Fetal mild hydronephrosis and chromosomal defects: relation to maternal age and gestation. Fetal Diagn Ther 1995;10:349-355.