Diagnosis of diaphragmatic tears

Twenty-five cases of torn diaphragm with herniation of abdominal contents and 22 cases without herniation were studied. Without herniation, the chest radiograph was in most cases normal or almost so, the remainder showing haemothorax or pneumothorax attributable to associated lung or rib injury. With herniation, however, the chest radiograph was infrequently normal and a substantial number showed basal abnormality directly due to herniated viscera. The appearances were still, however, non-specific and led to a number of preliminary misdiagnoses and therefore diagnostic delays. The herniated bowel can flatten out beneath the lung base to resemble merely a mildly elevated hemidiaphragm (the “pseudo-diaphragm effect”). Torn hemidiaphragm is a frequently forgotten diagnosis, but is of great importance because of hernial bleeding or strangulation. The peritoneopleural pressure gradient eventually produces herniation and this is usually diagnosable by barium study of stomach and colon. Small bowel studies are probably unnecessary. The limbs of the herniated loop are pinched together as they pass through the tear, sometimes severely enough to obstruct the barium. Insufflated air may get through into an apparently obstructed hernia. Because it is a “blind alley”, the herniated gastric fundus will not produce these typical appearances and will be missed unless one looks for the “amputated fundus” sign. Immediately following injury, normal barium studies do not necessarily indicate that there is no tear because there may not have been time for herniation to occur. The only available signs may therefore be the presence of a pneumoperitoneum or of intra-abdominal visceral injury following a downward stab to the lower chest, or of pneumothorax following abdominal injury. Diagnostic pneumoperitoneum may have a place. A left-sided predominance in all series is probably due to the liver cushioning the right hemidiaphragm from rupture in abdomino-pelvic crush injuries and also preventing bowel from herniating through established stab wounds.