From the Guidelines
Free air in scans is a medical emergency that typically indicates perforation of an organ, such as a hole in the stomach, intestines, or other hollow viscus, and requires immediate medical attention. This finding is often associated with severe infections, peritonitis, or other serious conditions. The presence of free air on imaging studies like X-rays, CT scans, or ultrasounds appears as dark areas in places where it shouldn't normally be present. Common causes include perforated ulcers, traumatic injury, recent surgery, or severe infections 1.
Key Considerations
- The presence of free air in scans is a significant finding that requires prompt evaluation and treatment to prevent further complications.
- The underlying cause of the free air, such as a perforated ulcer or traumatic injury, will guide the treatment approach.
- Hospitalization, antibiotics, and often surgical intervention are necessary to repair the source of the perforation and prevent further contamination.
- The patient's overall condition, including hemodynamic stability and presence of diffuse peritonitis, will influence the treatment strategy.
Treatment Approach
- Surgical intervention is often necessary to repair the source of the perforation, especially in cases of perforated diverticulitis, appendicitis, or peptic ulcer disease 1.
- Non-operative management may be considered in highly selected patients with free air, such as those with small amounts of distant intraperitoneal air and no clinical diffuse peritonitis or fluid in the fossa of Douglas 1.
- Antibiotics and supportive care, including nasogastric drainage and intravenous fluids, may be used in non-operative management, but close monitoring is necessary to assess for treatment failure and need for emergency surgery 1.
From the Research
Definition of Free Air in Scans
- Free air in scans, also known as pneumoperitoneum, refers to the presence of air in the abdominal cavity, which can be detected on plain abdominal radiographs or computed tomographic scans 2, 3.
- This condition can signify a leakage of air from a perforation in the gastrointestinal tract, but it can also result from other sources, such as pneumomediastinum and pneumothorax, or in patients who are being mechanically ventilated 3.
Detection of Free Air
- Free air can be detected on plain chest/abdominal radiographs, computed tomographic scans, or point-of-care ultrasound in the emergency department 2, 3, 4.
- The detection of free air has a remarkable predictive value for gastrointestinal perforation, with a sensitivity of 70% and a specificity of 93% at 2 days after surgery 5.
- A deep learning-based approach using convolutional neural networks can also be used to detect subphrenic free air on frontal chest X-ray images, achieving a sensitivity of 0.875 and a specificity of 0.825 6.
Clinical Significance
- The presence of free air in the abdominal cavity can be a life-threatening condition, requiring prompt and accurate diagnosis and treatment 2, 3, 6.
- Patient history and physical examination can assist in a preliminary diagnosis, but diagnostic imaging is essential for confirming the presence of free air and determining the cause and amount of air 3.
- Surgical versus nonsurgical conservative observation is determined on the basis of the cause and amount of free air, as well as the patient's overall condition 3.