Frimann-Dahl sign

The Frimann-Dahl sign is a diagnostic sign demonstrated when three dense lines, representing the sigmoid walls, are seen converging to the site of obstruction in sigmoid volvulus and associated with empty rectal gas .

History and etymology

Johan Frimann-Dahl (1902-82) was a Norwegian Professor of Radiology, and Head of the Roentgen Department from 1937-1972, at Ullevål Hospital, Oslo, Norway .