Waqas Masood

Proofread and Fact-check: Bochdalek Hernia Article Fact Sheet Overview Overview-Comparison A Bochdalek hernia is one of the two types of diaphragmatic hernia. It was named after A. Bochdalek, the physician who first described it in the 19th century and is a congenital abnormality [1]. The segregation between the abdominal cavity and the thoracic space is achieved by the diaphragm, which keeps the organs in their appropriate place. Occasionally, the posterior diaphragmatic attachment is impaired, because the pleuroperitoneal membrane fails to close during fetal development. This particular location is responsible for herniation phenomena, since the structure fails to restrain organs and keep them in place. A Bochdalek hernia is formed when organs located in the abdomen and especially the intestines and stomach, protrude through the posterior defective region of diaphragm. This type of hernia occurs primarily on the right posterior diaphragmatic side at a rate of 85%. A significant protrusion of a abdominal organ into the thoracic cavity usually causes symptomatology related to pulmonary function, as the lung will also be defective due to lack of space [2]. This constitutes a severe complication, as an infant may well succumb to respiratory arrest, if the hernia remains undiagnosed and the lung is extremely compromised. Bochdalek hernias are mostly diagnosed during infancy; in adults they are quite rare, with only a hundreds known cases of adult Bochdalek hernias worldwide [3]. A Bochdalek hernia constitutes 0.2 to 6% of all hernias of the diaphragm [4]. During the past years, with the advent of computerized tomography imaging (CT), the number of Bochdalek hernias diagnosed has exhibited an increase. Congenital diaphragmatic hernia (CDH) is characterized by a birth defect of the diaphragm. The most common category of CDH is Bochdalek hernia; other categories include Morgagni hernia and the hiatus hernia. A Bohemian anatomist, Vincent Alexander Bochdalek, first introduced Bochdalek hernia back in 1848 [1]. In Bochdalek hernia, there is a posterolateral defect in the diaphragm which is often accompanied by herniation of the stomach, intestines, liver, and/or spleen into the chest activity. If the embryonic pleuroperitoneal canal persists, a defect is present in the diaphragm, and herniation can occur through this opening. This defect is the foramen of Bochdalek. The larger hernias are often seen in the neonatal period and can contain omentum, spleen, and retroperitoneal fat. It is usually seen as a posterior lateral mass above the left hemidiaphragm. When present in the neonatal period, the infant may have an ipsilateral hypoplastic lung and respiratory distress. About 85% of Bochdalek hernias occur on the left side, about 10% on the right, and approximately 5% are bilateral [2]. Symptomatic Bochdalek hernias in adults are relatively rare, but the incidence of asymptomatic Bochdalek hernias in the adult population has been estimated to be anywhere between 1 in 2000 to 7000 based on autopsy studies to as high as 6% in early CT findings [3]. Bochdalek hernias comprise approximately 80-90% of all CDH [4]. Bochdalek hernias are routinely diagnosable with plain film frontal and lateral chest radiography. These hernias are evidenced by abnormal findings above the dome of the diaphragm, such as gas-filled loops of bowel or soft tissue mass. Due to the low sensitivity of plain film chest radiography, Bochdalek hernias may be confused for other thoracic pathology including left middle lobe collapse, air space consolidation, and pericardial fat pad, sequestration of the lung, mediastinal lipoma, or anterior mediastinal mass. Chest CT more accurately visualizes focal defects in the diaphragm and can definitively diagnose herniation in comparison to plain film chest radiography.  References 1. Shin MS, Mulligan SA, Baxley WA, Ho KJ. Bochdalek hernia of diaphragm in the adult. Diagnosis by computed tomography. Chest 1987; 92:-. 2. Mullins ME, Stein J, Saini SS, Mueller PR. Prevalence of Incidental Bochdalek's Hernia in a Large Adult Population. Am J Roentgenol. 2001; 177: 363-366. 3. MarFan MJ, Coulson ML, Siu SK. Adult incarcerated rightsided Bochdalek hernia. Aust NZ J Surg.1999; 69:239-41. 4. Gale ME. Bochdalek hernia: prevalence and CT characteristics. Radiology 1985; 156:449-52.