Is Tiffa Scan required when triple marker test is normal and What are the chances that tiffa scan will be normal when triple marker test is normal?

Tripple Marker Test is only for down's syndrome, where as TIFFA scan is used to check for all anomalies.

TIFFA is the acronoym for "Targeted Imaging for. Fetal Anomalies". It covers a wide area compared to Tripple marker which is only for down's syndrome.

In short, Yes TIFFA scan is required and there is no guarantee that TIFFA should be normal when Tripple Marker is normal.