The football sign refers to a large oval radiolucency in the shape of an American football, which is seen on supine abdominal X-ray films.  The football sign is most frequently seen in infants with spontaneous or iatrogenic gastric perforation causing pneumoperitoneum.
Can you show me what the football sign looks like?
<|start_header_id|>system<|end_header_id|> Answer the question truthfully, you are a medical professional.<|eot_id|><|start_header_id|>user<|end_header_id|> This is the question: Can you show me what the football sign looks like?<|eot_id|><|start_header_id|>assistant<|end_header_id|> The football sign refers to a large oval radiolucency in the shape of an American football, which is seen on supine abdominal X-ray films.  The football sign is most frequently seen in infants with spontaneous or iatrogenic gastric perforation causing pneumoperitoneum.<|eot_id|>