MIE is being performed more frequently in patients with esophageal cancer, and a previous report indicated that HH occurs more often after MIE than after OE . The reasons for this difference are the reduction of peritoneal adhesions in the hiatal region and the extensive dilation of the hiatus resulting from insufflation and iatrogenic manipulation during MIE [2, 5, 6]. Early ambulation as a part of an enhanced recovery program is also considered to contribute to the development of HH because it may increase the intra-abdominal pressure . Additionally, some reports have described the relationship between BMI and HH [7, 8]. We previously reported the development of HH after OE  and MIE . Unfortunately, we experienced three cases of retrosternal hernia after TLE.
A retrosternal hernia is one type of internal hernia defined as herniation of the intestine into the thoracic cavity by the retrosternal route. Retrosternal hernias may be categorized into two types: localized and extended. Localized hernias are located only in the retrosternal space. In contrast, extended hernias have spread not only to the retrosternal space but also to the thoracic cavity.
The common risk factors for both types of retrosternal hernia are the same as those for HH: reduction of peritoneal adhesions, extensive dilation of the retrosternal orifice, excessive intra-abdominal pressure, early mobilization, and low BMI. One risk factor that differs is injury to the mediastinal pleura induced by negative pressure derived from the thoracic cavity. Uemura et al.  concluded that injury to the mediastinal pleura introduces the reconstructed organ to the thoracic cavity by the negative pressure of breathing. We used the gastric tube as the reconstructed organ in the three patients described in the present report, but the intestine was drawn into the thoracic cavity by the retrosternal route. This is the first report to describe the herniation of the intestine instead of the reconstructed organs into the retrosternal space and thoracic cavity.
In our patients, no surgical injury to the pleura occurred during the laparoscopic procedure. However, even when no injury occurs during the operation, the mediastinal pleura may become weak because of the loss of surrounding tissue. This weak pleura may be intolerant to the high intra-abdominal pressure caused by constipation, leading to pleural injury. In addition, the retrosternal orifice was widely opened by a burn injury in one of our patients. This widely opened orifice might also lead to intestinal herniation.
As for treatment, the retrosternal hernia is controversial [2, 6, 11, 12]. Based on our experience, two approaches can be considered. First, if CT reveals no ischemic change to the herniated contents, reduction and control of the intra-abdominal pressure might lead to a reduction of the herniated contents into the abdominal cavity. In case 3, despite the presence of an extended type hernia with negative pressure derived from the thoracic cavity, relief of the intra-abdominal pressure successfully reduced the herniated contents. Second, if the decrease in the intra-abdominal pressure is unsuccessful, surgical repair is needed. We chose open laparotomy instead of laparoscopy because we expected postoperative adhesions around the retrosternal orifice. We also performed reefing of the dilated retrosternal orifice and anchored the gastric conduit to the ventral wall. This procedure may be essential for preventing herniation after MIE. If this suturing technique is enough to prevent a retrosternal hernia, then laparoscopic repair is another treatment choice.
To prevent a retrosternal hernia after MIE, close attention must be paid to the procedure by which the retrosternal route is established. Uemura et al.  concluded that the use of a video-assisted maneuver might prevent injury to the parietal pleura during blunt dissection of the retrosternal space. Based on our cases, the retrosternal orifice should not be opened widely. The retrosternal orifice should be of adequate size for the gastric conduit and omentum with respect to both vascularity and hernia formation. A small amount of the omentum and a large orifice will lead to a retrosternal hernia. The pleura should not be injured without dissection of the surrounding tissue, and the intra-abdominal pressure must be controlled.
In summary, we experienced three cases of a retrosternal hernia as a rare complication after MIE. Surgeons should be aware of this uncommon complication if retrosternal route reconstruction is used after MIE. As MIE is performed more frequently in the near future, retrosternal hernia may become an increasingly more common complication.