Which finding requires prompt laparotomy in a 10-year-old girl post-splenic injury?

The presence of free peritoneal air demonstrated on follow-up CT indicates that there is likely a perforation in the gastrointestinal tract or a significant intraperitoneal injury following the splenic injury. This finding is critical as it suggests there is a breach in the integrity of the abdominal cavity, leading to the possibility of contamination by air or bacteria from the gastrointestinal tract, which can result in peritonitis and severe complications.

Immediate surgical intervention, such as a laparotomy, is essential to address the source of the perforation, clean the peritoneal cavity, and prevent further complications such as sepsis or widespread abdominal infection. The urgency is heightened in pediatric patients, who may not always present with the classic symptoms that would indicate a need for surgery, making imaging results like free air prominent indicators of an impending surgical necessity.

Other parameters, while significant, do not indicate an immediate surgical requirement. For instance, an elevated serum amylase can be related to various other conditions that don't necessitate a prompt laparotomy, such as pancreatitis or other non-surgical abdominal issues. Similarly, a leukocyte count of 14,000 may suggest infection or inflammation, but it does not alone confirm the need for urgent surgery. Lastly, a fall in hem