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Background
Recreational scuba diving is an ever-growing popular activity among people of all ages. Though originally centered along coastal areas, recreational divers are to an increasing extent found in inland bodies of water, like artificial facilities and freshwater lakes. Furthermore, the popularization of scuba diving is leading to the involvement of inexperienced divers, who may be more prone to errors during descent or to uncontrolled rapid ascent. Despite the minimal amount of references in peer-reviewed literature, with the growing participation in diving activities, the emergency radiologist must be trained to recognize and appropriately diagnose the more uncommon complications of decompression sickness and barotrauma.

Educational Goals / Teaching Points
By the end of this exhibit, the participant should be able to navigate proficiently the anatomy of peritoneal and retroperitoneal spaces; be familiar with the general radiological signs of gastrointestinal perforation; understand the pathophysiology and presentation of barotrauma in decompression accidents; and know the appropriate imaging work-up in a patient with suspected gastrointestinal decompression barotrauma.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Barotrauma is defined as physical tissue damage caused by an unrelieved pressure differential between a surrounding gas or fluid and an unvented body cavity (e.g., lungs, hollow viscera) or across a tissue plane. The damage is due to compressive or expansive forces and shear, leading to overstretching of tissues. Barotrauma can occur during ascent or descent. During ascent, the diminishing ambient pressure determines expansion of the gas contained within a body cavity, according to Boyle-Mariotte's law. If this pressure differential is not equalized, tissue injury may result from the forces generated by the difference between the ambient pressure and the body cavity. If this happens in the context of a hollow viscus, the rash increase in internal pressure may lead to perforation or even rupture. The presentation may be extremely nuanced, varying from mild, nonspecific signs and symptoms to an acute abdomen, requiring emergency surgical evaluation.

Conclusion
Though usually mainly associated with arterial gas embolism, decompression sickness can manifest itself with a variety of conditions. With the ever-increasing interest in scuba diving, the emergency radiologist must be trained to recognize and correctly assess even the more uncommon complications of decompression sickness, like decompression-induced gastrointestinal perforation or rupture. A standardized and appropriate imaging work-up is of fundamental importance to the effective management of the patient.