Three signals are observed for all probes used in this assay. Given the ultrasound anomalies, the diagnosis of triploidy is the most likely explanation.
If the fetus has tetraploidy, four signals would be observed for each probe used in this assay.
Although the fetus does indeed have trisomy of these chromosomes, multiple aneuploidy involving five chromosomes has not been reported prenatally. The three signals observed for each of these chromosomes are an indication that there is an extra set of ALL chromosomes; that is, triploidy.
Trisomy of chromosomes 13, 16, 18, 21, and 22 has not been described as a malignant event in chorionic villi obtained from a 10-week-old fetus.
Multiple signals are commonly observed in FISH analyses and are not an indication of assay failure.