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INTRODUCTION

The majority of diaphragmatic hernias diagnosed in adults arise either at the esophageal hiatus or as a delayed complication of previous diaphragmatic injury. In neonates, diaphragmatic hernia occurs in 1 of 2000–12,500 live births and constitutes 8% of significant congenital anomalies.1 The defect results from failed closure of the diaphragm during embryogenesis. The most common location of these hernias is in the posterolateral position (Bochdalek hernia).2 Bochdalek hernias cause significant morbidity and mortality in the neonatal period; the presentation is rarely delayed until adulthood. Less frequently, the anterior portion of the diaphragm fails to fuse substernally (Morgagni hernia).3 Morgagni hernias carry less early morbidity and are somewhat more likely to be detected in older patients. Late adult recurrence of congenital diaphragmatic hernias repaired in the neonatal period is extremely rare.4

The consensus opinion based on a number of case series is that Bochdalek and Morgagni hernias in adults should be repaired in medically fit patients even in the absence of symptoms owing to risk of catastrophic complications. The most common approach to Morgagni hernias has typically been primary repair via laparotomy, whereas Bochdalek hernias may be approached either by laparotomy or thoracotomy and are more likely to require prosthetic material. In recent years, minimally invasive approaches to both conditions have become increasingly widespread.5,6

ANATOMIC CONSIDERATIONS

The adult diaphragm forms from the fusion of the septum transversum (precursor to the central tendon) anteriorly, the pleuroperitoneal membranes posterolaterally, and the dorsal mesentery of the esophagus.6 The diaphragm anlage forms between the fourth and twelfth week of gestation and then descends from a cervical position to the abdomen. Aberrant development of the pleuroperitoneal membrane leads to formation of a Bochdalek defect, with resultant herniation of stomach, spleen, small intestine, colon, and omentum into the left hemithorax and subsequently impaired lung development. The Morgagni hernia results from a weak point in the substernal portion of the septum transversum and most commonly contains omentum or transverse colon and omentum.

EPIDEMIOLOGY AND PRESENTATION

About 5% of Bochdalek hernias8 and a similar portion of Morgagni hernias are detected in adults. Assorted other congenital anomalies are present in about 10% of adult patients6 with Bochdalek hernias. A possible association exists between Morgagni hernia and trisomy 21,9 and missed congenital hernia should be considered as a possible explanation for abdominal discomfort or exercise intolerance in this population. Congenital diaphragmatic hernias may be acquired in adulthood due to widening or reopening of the pleuroperitoneal ducts8; the presence of previously normal imaging does not rule out congenital diaphragmatic hernia (CDH) in adulthood.

CDH in adults may be incidental, symptomatic, or a surgical emergency. A review of more than 13,000 abdominal CT scans in 1 year at a single institution detected Bochdalek hernias in 0.17% of patients, none of whom had ...

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