Diagnosing fetal urinary tract abnormalities: benefits of MRI compared to ultrasonography.
BACKGROUND
To compare antepartum ultrasonography with magnetic resonance imaging for prenatal diagnosis of malformations in the fetal urinary tract in high risk patients during the last trimester.


METHODS
The study involved 22 women and 24 fetuses with either severe oligohydramnios or ultrasonographically or clinically suspected abnormality of urinary tract. Ultrasound examination was carried out with 5 MHz abdominal convex probe and magnetic resonance imaging with superconductive 1.5 T equipment. Postnatal findings were used as reference.


RESULTS
Correct diagnosis of urinary tract anomaly was done in 15 fetuses on ultrasound and in 20 fetuses on magnetic resonance imaging. Both methods enabled correct diagnosis in 12, only ultrasound in three and only magnetic resonance imaging in eight fetuses. Both methods imaged equivocally in one case. The additional information by magnetic resonance imaging was gained from five fetuses out of 12 pregnancies with oligohydramnios and from three fetuses out of ten pregnancies with normal amount of amniotic fluid.


CONCLUSIONS
MRI is a valuable additional method to ultrasonography of fetal urinary tract if resolution of ultrasound is impaired for reason of oligohydramnios or technical deterioration.
Poutamo
J
J
Department of Obstetrics and Gynecology, University Hospital of Kuopio, Finland.
Vanninen
R
R
Partanen
K
K
Kirkinen
P
P
D000013:Congenital Abnormalities / Q000175:diagnosis / Q000000981:diagnostic imaging; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis / Q000601:surgery; D006801:Humans; D007668:Kidney / Q000002:abnormalities* / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D018566:Pregnancy, High-Risk; D011296:Prenatal Diagnosis; D016216:Ultrasonography, Prenatal