Tension pneumoperitoneum is a special and rare type of pneumoperitoneum, in which the free intra-abdominal peritoneal gas is under pressure.
The mechanism is thought to be a ball-valve effect allowing the one-way accumulation of gas. This results in:
- elevation and splinting of the diaphragm reducing lung volumes
- compression of intra-abdominal venous structures, e.g. inferior vena cava, resulting in reduced venous return and decreased cardiac output
Causes are essentially the same as those of a 'normal' pneumoperitoneum with iatrogenic causes e.g. mechanical ventilation, being over-represented.
The radiographic features are the same as a routine pneumoperitoneum except that gas volumes are vast and abdominal distension is present.
Treatment and prognosis
Just as in tension pneumothorax, prompt intervention is required to prevent death.