reveals a nasogastric tube in the distal esophagus and a large left-sided air and fluid collection. Another section, more caudal and viewed at lung windows (D), reveals that the air lies inside the herniated colon. (Courtesy of Marc Gollub, MD, New York, NY)

side of the mediastinum includes a left-sided gastric pull-through (Fig. 2.23), a mucocele [78], and a pneumo- or hydropneumothorax [77]. Occasionally, this differentiation is made easier by the presence of haustrations or the continuity of the air into subdiaphragmatic bowel [77]. The herniation is usually that of colon, but small-bowel herniation has also been reported [77,79-81]. The incidence of herniation is estimated to be no more than 4% [79,80]. A retrospective review of nine cases of herniation found the most significant risk factor to be that of an extended enlargement of the diaphragmatic hiatus during the gastric pull-through [81].

These herniations are usually noted during the acute postoperative phase on routine chest films. They can be confirmed by CT imaging and/or by routine contrast studies of the bowel. Some patients are asymptomatic; some have cough, dyspnea, or other signs of respiratory distress; others present with signs and symptoms of bowel obstruction [79,81] or strangulation [77]. A rare instance of extraperi-cardial tamponade by herniated omentum has also been reported [82]. Therefore it has been recommended to electively close (narrow) the esophageal diaphragmatic hiatus after the stomach has been delivered into the chest and before closure of the abdomen [80,82]. Others recommend performing an omentectomy to remove the possible leading edge for the herniation [79].

Occasionally, in both benign and malignant disease, the esophagus cannot be resected before surgical bypass is performed. This restriction might be secondary to unresectable malignancy or periesophageal inflammatory changes in cases of trauma or caustic ingestion [83,84]. In these instances, the thoracic esophagus is isolated (excluded) from the remainder both proximally and distally, by ligation or stapling the esophagus and then dividing it. Gastrointestinal continuity is then restored with either the stomach or colon. This procedure is fraught with difficulty, and complication rates of up to 60% have been reported [84]. The complications include anastomotic leaks, disruption of the distal portion of the isolated esophagus, fistula formation, and infection.

A well-described complication of leaving the esophagus in situ is that of an esophageal mucocele. This is defined as a closed, cystic space containing secretions high in protein [84]. This is secondary to continuing production of mucus by the submucosal glands and not secondary to adenomatous metaplasia, as might be suspected [78]. Mucoceles may occur in as many as 40% of patients in whom the esophagus cannot be resected [84]. Eventual increases in the esophageal remnant intraluminal pressure result in atrophy of these glands and subsequent arrest of the enlargement [78,84].

The onset of an esophageal mucocele usually occurs in the first two postoperative months, and most often the cyst remains stable in size [84]. Although rare, continued enlargement due to continued mucus production has been reported [84]. Esophageal mucoceles are usually small (mean 4 x 6.5 cm) and more often related to either the proximal or distal end of the excluded esophagus [84]. However, they may involve its entire length [78,84]. Obviously, routine contrast

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