A 30-year-old male presents after a motor vehicle crash. Which finding indicates laparotomy is necessary?

In the context of a motor vehicle crash, the presence of retroperitoneal air noted on a CT scan is a significant finding that often indicates the need for laparotomy. Retroperitoneal air suggests a breach in the integrity of the retroperitoneal structures, which could imply serious injuries to organs such as the aorta, kidneys, or major vascular structures. This finding typically raises concerns for significant intra-abdominal trauma that may necessitate surgical intervention to prevent further complications such as hemorrhage or infection.

To elaborate, the presence of retroperitoneal air can indicate that there is a perforation or laceration allowing air to enter the retroperitoneal space, which is not normal and indicates a potential for grave injuries. A surgical evaluation through laparotomy can then clarify the situation and allow for necessary repairs.

In contrast, the other options, while they indicate significant injuries, do not universally necessitate immediate laparotomy. A distinct seat belt sign could indicate abdominal trauma but doesn't directly correlate with the need for surgery without other findings. An extraperitoneal bladder injury may often be managed conservatively unless there are complicating factors. A Grade 4 hepatic injury does indicate a severe injury but may sometimes be managed with non-operative approaches depending