A prospective study of the association between isolated fetal pyelectasis and chromosomal abnormality.
OBJECTIVE
To determine the incidence of chromosomal abnormalities among fetuses with isolated pyelectasis.


METHODS
Between March 1991 and March 1994, 121 cases of isolated fetal pyelectasis were identified at our institution. Pyelectasis was defined as a renal pelvis anteroposterior diameter of at least 4 mm before 33 weeks' gestation, and at least 7 mm at 33 weeks or thereafter. Once identified, women were offered antenatal genetic testing; if they declined, consent was sought for umbilical cord blood studies at delivery.


RESULTS
Chromosomal evaluation was available in 99 women. Two chromosomal abnormalities were identified: one trisomy 21 and one mosaic 46, XY/47, XYY. The ages of the women were 32 and 28 years, respectively. Calculation of adjusted risks for Down syndrome and all chromosomal abnormalities indicated a 3.9-fold increase in Down syndrome risk and a 3.3-fold increase in risk for all chromosomal abnormalities in the presence of isolated fetal pyelectasis.


CONCLUSIONS
Isolated fetal pyelectasis is associated with increased risk, over that related to age, for both Down syndrome and all chromosomal abnormalities. These factors may be valuable in counseling individual patients regarding the appropriateness of amniocentesis.
Wickstrom
E A
EA
Department of Obstetrics and Gynecology, Northwestern University Medical School, Chicago, Illinois, USA.
Thangavelu
M
M
Parilla
B V
BV
Tamura
R K
RK
Sabbagha
R E
RE
D000328:Adult; D000649:Amniocentesis; D015193:Chorionic Villi Sampling; D002869:Chromosome Aberrations / Q000175:diagnosis / Q000453:epidemiology*; D025063:Chromosome Disorders; D004108:Dilatation, Pathologic / Q000000981:diagnostic imaging / Q000453:epidemiology; D004314:Down Syndrome / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging* / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007621:Karyotyping; D007682:Kidney Pelvis / Q000000981:diagnostic imaging* / Q000196:embryology; D008423:Maternal Age; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D016216:Ultrasonography, Prenatal