A patient is experiencing lower left quadrant pain with guarding, as well as abdominal distention...

The clinical presentation of lower left quadrant pain with guarding, abdominal distention, rigidity, and free air in the abdominal cavity on a KUB (kidney, ureter, and bladder) radiograph strongly suggests a perforated bowel. The presence of free air indicates that there is a breach in the gastrointestinal tract, allowing air to escape into the peritoneal cavity. The patient's vital signs, including hypotension (BP 76/40), tachycardia (HR 130), tachypnea (RR 32), and fever (T 101.7°F), are consistent with sepsis and shock, which are common complications of bowel perforation. References: CCRN Exam Handbook, AACN, page 30, section on Gastrointestinal.