Pad sign | Radiology Signs

Answer:
The antral pad sign is a radiographic observation on upper gastrointestinal contrast radiography where there is a smooth, arcuate indentation or contour irregularity of the posteroinferior aspect of the distal gastric antrum. This is caused by extrinsic soft tissue compressing or abutting the gastric antrum, leading to a cushioned appearance on imaging. A distended gallbladder is the single most common cause; other causes include chronic pancreatitis, pancreatic pseudocyst or neoplasm, and hepatic masses, as these conditions may displace or compress the gastric antrum.

Why is it called so?

The term “antral pad” refers to the impression of a soft, pad-like structure indenting the antral region of the stomach. The word “pad” underscores the cushioning effect of the adjacent organ mass, while “sign” indicates its role as a recognizable radiographic marker on contrast radiography.

Pathophysiology

The antral pad sign develops when an adjacent visceral mass—most commonly a distended gallbladder, but also an enlarged pancreas in chronic pancreatitis, a pancreatic neoplasm/pseudocyst, or hepatic enlargement—exerts pressure on the distal gastric antrum. This extrinsic compression deforms the antral wall, which becomes outlined by intraluminal contrast during the upper gastrointestinal series. On imaging, it appears as a smooth, concave impression against the antrum, reflecting the interface between the stomach and the compressed organ.

Alternative names: Antral padding

Other associated named signs: Frostberg’s inverted-3 sign (medial displacement/indentation of the descending duodenum by an enlarged pancreatic head)

References

1. Asrani AV. The antral pad sign. Radiology. 2003.
2. Smeets R, Op den Orth JO. Gallbladder: common cause of antral pad sign. AJR Am J Roentgenol. 1979.