Early diagnosis and active management of trans-anal rectal injuries is essential for a favorable outcome. Intraperitoneal free air (IFA) is usually diagnosed by an erect Chest X-ray. Point-of-care ultrasound has been recently used to detect IFA. We report a 45-year-old male who presented to the Emergency Department with lower abdominal peritonitis. Surgeon-performed portable point-of-care ultrasound as an extension of the abdominal examination revealed an inflamed omentum with hypoechoic stranding, thickened non compressible small bowel, and free fluid in the pelvis. A transverse abdominal section of the right upper quadrant showed free intraperitoneal air. Rectal examination revealed a longitudinal rectal tear. Laparotomy has confirmed the sonographic findings. There was a 12 cm intraperitoneal tear of the anterior wall of the rectum which was necrotic. This case clearly demonstrates that portable point-of-care ultrasound gives very useful detailed information even when performed by a non radiologist. Surgeons should be encouraged to use point-of-care ultrasound after appropriate training.