Strangulated Bochdalek Hernia: Approach of Management in Emergency Setting

Bochdalek hernia is a type of congenital diaphragmatic hernia that primarily manifests in children however in rare instances they do manifest in adulthood spontaneously or after physical exertion. We report a case of a left-sided Bochdalek hernia in an adult who presented with left-sided chest pain and worsening symptoms of dyspnea. His chest radiograph revealed dilated small bowel loops in the left hemithorax causing a mediastinal shift. A computed tomography done revealed a posterolateral diaphragmatic defect through which the abdominal viscera had herniated. He was subsequently intubated due to severe respiratory distress. The patient underwent an emergency laparotomy which revealed a large 10 cm posterolateral diaphragmatic defect with herniation of small bowel, spleen and transverse colon. The small bowel was gangrenous and perforated therefore a primary repair of the defect with non-absorbable sutures was done. Gangrenous bowel was resected and primary anastomosis was done. Postoperatively, the patient had significant clinical improvement and was discharged a week later with no immediate complications.


INTRODUCTION
Bochdalek hernia is a diaphragmatic hernia that results from a failure of the posterolateral diaphragmatic foramina to fuse in utero. Although mainly detected in childhood they can manifest in adulthood with a reported incidence rate as low as 0.17% and as high as 6% of all diaphragmatic hernias (1). The clinical presentation of a Bochdalek hernia in an adult is exceptionally rare. In 1959, Kirkland published the first review of adult Bochdalek hernia which included 34 cases and as of 1992 only 100 cases of symptomatic adult Bochdalek hernia have been reported in world literature (2). In adults, most Bochdalek hernias are detected as an incidental finding on computed tomography (CT) scan of the abdomen in asymptomatic adults, alternatively, it may be diagnosed only after complications occur. The clinical presentation of adult Bochdalek hernia is variable and is mainly confined to the respiratory or gastrointestinal systems; which makes the diagnosis even more difficult. Symptomatic Bochdalek hernia may lead to incarcerated or strangulated bowel, intraabdominal organ dysfunction and severe respiratory disease. Imaging plays a vital role in diagnosing and assessing the contents of the hernia and at the same time evaluating the presence of any associated abnormality. We describe a middleaged gentleman who presented to us with strangulated Bochdalek hernia.

CASE REPORT
A 49-year-old man presented to the emergency department of a district hospital with worsening symptoms of left-sided chest pain and dyspnea over a 3day period. He had no prior known medical illnesses and denied any history of trauma or physical exertion. He also complained of difficulty to open his bowels and pass flatus since the onset of his primary symptoms. On examination, he was hypertensive and tachycardic. Auscultation revealed decreased air entry of the left side and per abdomen examination showed a tender epigastrium with no abdominal distension or peritonitis. His chest radiograph ( Figure 1) showed dilated small bowel loops in the left hemithorax with significant mediastinal shift to the right. CT of the thorax and abdomen (Figure 2 and 3) was done immediately and showed a large left posterolateral diaphragmatic hernia with herniation of small bowel and mesenteric fat. The defect involved both diaphragmatic muscle and fascia. Small bowels were twisted around the mesentery causing a closed-loop obstruction, however, no evidence of ischemia was seen at the time. He was subsequently intubated due to worsening respiratory distress and was transferred to a tertiary centre for further definitive management.   The patient was posted for surgery and intraoperative findings revealed herniation of small bowel, transverse colon, and small bowel through a posterolateral defect around 10 cm (Figure 4). After reduction of the hernia contents into the abdominal cavity, noted a segment of ileum was gangrenous with perforation resulting in a litre of faecal contamination of the left hemithorax. The gangrenous segment of bowel was resected and primary anastomosis was performed. The hemithorax was lavaged sufficiently and the posterior diaphragmatic defect was repaired with interrupted non-absorbable monofilament sutures (Prolene 1/0, Ethicon Inc; Johnson & Johnson, Somerville, NJ, USA). A polypropylene mesh was not used due to gross contamination. A single chest tube and a pelvic drain were inserted prior to closure. Postoperatively, the patient had an uneventful recovery and was discharged home a week later with no complications.

DISCUSSION
The foramen of Bochdalek is 2 x 3 cm opening in the posterior aspect of the diaphragm in the fetus. It is through this opening the pleuroperitoneal canal communicates between the pleural and peritoneal cavities. This foramen usually closes at 8 weeks of gestation however failure or incomplete fusion of the lateral with posterior crural components of the diaphragm leads to a Bochdalek hernia formation. The left canal closes later than the right canal resulting in this hernia being found more prevalent on the left (1). Presentation of symptomatic Bochdalek hernia in adults varies with most patients presenting with chest pain, dyspnea, dyspepsia and even features of intestinal obstruction. This particular patient presented to us with classical symptoms of left-sided chest pain, dyspnea with features of intestinal obstruction without any aggravating factors. A high degree of suspicion and prompt imaging studies are vital to an early diagnosis and accurate management of the disease (3).
Bochdalek hernia can be routinely diagnosed by plain frontal and lateral chest radiographs however it lacks sensitivity and maybe confused with other thoracic pathologies such as hydropneumothorax, lobar collapse and mediastinal mass (2,4). In fact, the sensitivity of detecting a diaphragmatic hernia using chest radiograph ranges from 23-73%, in comparison with sensitivity of conventional CT of 14-61% and specificity of 76-99% (5). Whereas the sensitivity of helical CT in detecting diaphragmatic hernia of 71% and with a specificity of 100% (6). Multiplanar reconstruction on coronal, sagittal and axial images of helical CT images enable high sensitivity and specificity (6). Therefore, helical CT of the thorax and abdomen is deemed the most accurate way to diagnose and evaluate contents of the hernia as well as detection of the thoracic cavity and other associated anomalies. Classically, CT signs of diaphragmatic hernia includes direct visualisation of the diaphragmatic defect, visceral intrathoracic herniation and collar sign (5). The collar sign is described as a "waistlike constriction" of the herniated structure at the site of diaphragmatic defect (7). Thankfully, our patient did not show any other thoracic or abdominal organ anomalies that may have suggested chronic herniation.
The treatment of Bochdalek hernias are mainly surgical and are associated with good postoperative outcome. In our case, the patient was suspected to have some degree of strangulation as evidenced by dilated small bowel loops associated with a closed-loop obstruction. Therefore, we chose a transabdominal approach via a midline laparotomy. A mesh repair was not performed due to significant contamination of bowel contents. However, in the absence of strangulation, gangrene or obstruction, a transthoracic or a laparoscopic approach with polypropylene mesh repair should be considered (8,9).

CONCLUSION
Asymptomatic Bochdalek hernias in adults are rare and require a high degree of medical acumen paired with prompt imaging studies. Chest radiography is a good screening tool but thin-section CT scanning has higher sensitivity for these lesions. Surgical approach whether transthoracic versus transabdominal, open versus laparoscopic, should be planned carefully to avoid any unwanted complications that impair recovery and result in a recurrence of the hernia.