Continuing Education Activity

A diaphragmatic hernia (DH) is a protrusion of abdominal contents into the thoracic cavity due to a defect within the diaphragm. It is most common as a congenital phenomenon; however, it can also be acquired. Most commonly, acquired DH occurs following blunt or penetrating trauma, which results in a rupture of the diaphragm and herniation of abdominal content. Additionally, acquired DH can also occur spontaneously or by iatrogenic causes. Acquired DH is rare but can be life-threatening, resulting in intestinal incarceration and strangulation with an increased mortality rate. This activity reviews the evaluation and treatment of diaphragmatic hernia and highlights the role of the interprofessional team in managing this condition.

Objectives:

• Summarize the etiology of diaphragmatic hernias.
• Review the risk factors for developing a diaphragmatic hernia.
• Outline the typical presentation of a patient with a diaphragmatic hernia.
• Review the importance of improving care coordination amongst interprofessional team members to improve outcomes for patients presenting with diaphragmatic hernias.

Introduction

A diaphragmatic hernia (DH) is a protrusion of abdominal contents into the thoracic cavity due to a defect within the diaphragm. It is most common as a congenital phenomenon; however, there have also been cases where it can be acquired.[1] Reports place its incidence at approximately 0.8-5/10,000 births.  Most commonly, acquired DH occurs following blunt or penetrating trauma, which results in a rupture of the diaphragm, which is then accompanied by herniation of abdominal content. Additionally, there are cases reported where acquired DH can also occur spontaneously or by iatrogenic causes.[2] Acquired DH is rare but can be life-threatening, resulting in incarceration and strangulation with an overall mortality rate of up to 31%.[3]

Congenital diaphragmatic hernia (CDH) refers to a developmental defect of the diaphragm that will result in the herniation of abdominal viscera into the chest cavity. Neonates with CDH usually present early in the first few hours of life with respiratory distress. The respiratory distress accompanied by the CDH may be mild. Occasionally the accompanied respiratory distress is so severe and can be life-threatening. With antenatal diagnosis and improved neonatal care, survival has been remarkably improved, but there is still a notable risk of morbidity and mortality in infants with CDH.[4]

Diaphragmatic injury is rare, complicating less than 1 percent of all traumatic patients.[5][6] However, the incidence includes up to 3% of all abdominal injuries.[7] Isolated diaphragmatic injuries are quite uncommon and are usually reported in the context of complicated abdominal and thoracic injuries. Notwithstanding the probability of an obvious herniated abdominal viscera in the thoracic cavity in the chest x-rays, the subtle cases should not be underestimated. Therefore, a high index of suspicion is strongly recommended to avoid the debilitating morbidity associated with delayed and missed diagnosis.[3] 

Etiology

The most common etiology of acquired diaphragmatic hernia (ADH) is secondary to trauma which results in diaphragmatic rupture. It occurs more often from blunt trauma but can also result from penetrating thoracoabdominal trauma.[8] Diaphragmatic rupture from thoracoabdominal trauma occurs in approximately 0.8 to 3.6% of cases, with the incidence of herniation following such an event being relatively low.[8][9] Iatrogenic causes following surgery are the second most common cause of ADH. However, they are very rare, mostly just case studies in the literature. The most common surgeries with which DH has been associated and reported are following pediatric liver transplants and liver resection.[10][11] Other documented episodes of ADH post-surgery within case studies include Nissen fundoplication, left colectomy, adrenalectomy, laparoscopy-assisted total gastrectomy, nephrectomy, and partial resection of the left lung using thoracoscopic surgery.[12][13][14][15][16][17][18] Spontaneous defects have also been noted; in these cases, they may be asymptomatic for years before becoming symptomatic in the later stage, where the defects can be extensive.[2] Other rare causes documented within case studies include following radio-frequency ablation for hepatocellular carcinoma and during pregnancy.[19][20][21]

According to one of the major reviews, including more than 53,000 patients with blunt and penetrating abdominal trauma, diaphragm injury was reported in up to 3 % of the cases. Moreover, the reports suggested the 2 to 1 ratio of penetrating versus blunt traumatic diaphragm injury in the studied population. Similar results were reported by the National Trauma Data Bank. (1 to 7 % versus 10 to 15 %)[7][22][7]

Epidemiology

Acquired diaphragmatic hernia is rare. Diaphragmatic rupture from thoracoabdominal trauma occurs in approximately 0.8 to 3.6% of cases, with the incidence of herniation following this being relatively low.[8][9] The number of patients affected by ADH from other causes is not documented and is most commonly noted within case studies.

Pathophysiology

Acquired diaphragmatic hernia (ADH) due to trauma to the diaphragm is likely to occur at areas of potential weakness along embryological fusion points.[23] It is thought to be produced by a sudden increase in the pleuroperitoneal pressure gradient due to the trauma.[23] Multiple factors may result from iatrogenic causes depending on the type of surgery, patient-related factors, and technique used to close the diaphragm.[11] ADH and diaphragmatic rupture tend to occur more commonly on the left side of the diaphragm. This tendency is likely due to the right hemidiaphragm being protected by the size of the liver beneath it.[24] Right-sided ruptures and herniations are very rare and associated with higher mortality and morbidity rate.[23] The abdominal contents that can herniate into the diaphragm vary, but documented cases include herniation of the stomach, small intestine, mesentery, splenic, and pancreas.[3]

To clarify the penetrating trauma and the potential for traumatic diaphragmatic injury (TDI), the anatomical landmarks of the diaphragm should be reviewed. The anatomical differences during the inspiration and expiration phases should be considered. Accordingly, the diaphragm rises during the expiration up to the fourth and fifth thoracic dermatome on the right and the left hemithorax, respectively. Also, the diaphragm descends to as low as the eighth thoracic dermatome during the deep inspiration. However, the lowest level of the lateral costophrenic angle attachment is the 12 rib. Collectively, any missile that passes through the torso from T4 through T12 can potentially penetrate the diaphragm. It should be noted that the higher rate of the left TDI with stab wounds is presumably, because of the higher prevalence of right-handed assailants.[25]

Blunt diaphragmatic trauma: motor vehicle collisions are responsible for most blunt diaphragmatic ruptures in almost 90 percent of cases. Falling down and crushing injuries imply the remaining causalities of blunt diaphragmatic trauma. A significant increase in intra-abdominal pressure is required for diaphragmatic rupture in the mentioned clinical scenarios.[26]

During the inspiration phase and with the diaphragmatic contraction, the diaphragm flattens. The flattened diaphragm increases the volume of the thoracic cavity, and accordingly, the pleuroperitoneal pressure gradient can increase from +7 to +20 cm HO in the supine position to +100 cm HO. The blunt force trauma to the torso can result in pleuroperitoneal gradients of up to 200 cm HO. The mentioned remarkable increase in pleuroperitoneal gradient surpasses the diaphragmatic tensile strength and results in diaphragmatic rupture or avulsion.[27]

Congenital Diaphragmatic Hernia (CDH):

To understand the pathophysiology of CDH, the embryologic development of the diaphragm should be reviewed. The diaphragm originates from four main structures, including; 1. the septum transversum, 2. the esophageal mesentery, 3. two paired (pleuroperitoneal membranes, and 4. chest wall muscular structures.[28]

Septum Transversum: The development of the septum initiates in the fourth gestational week to separate pericardial and peritoneal cavities. Starting next to the cervical vertebrae, the septum transversum finally outgrows to the level of the first lumbar vertebrae (L1). Next, dorsal fusion with the esophageal mesentery and pleuroperitoneal membranes would occur. Esophageal mesentery similarly develops in the fourth gestational week and will eventually form the central portion and crura of the diaphragm.

The pleuroperitoneal membranes develop later in the fifth week of gestation, appearing initially parallel to the abdominal wall with the later medial extension. Finally, pleuroperitoneal membranes will fuse with the dorsal borders of the esophageal mesentery and septum transversum. The complete fusion will result in a discrete separation of the thoracic cavity from the abdominal cavity during the eighth gestational week. Failure of steps and incomplete fusion with adjacent structures may result in CDH.[29]

History and Physical

Most ADH cases follow either blunt or penetrating trauma to the thorax or abdomen. A clear history of trauma should prompt appropriate imaging to determine the extent of the injury, which may then demonstrate the presence of ADH. For other causes of ADH, it is crucial to consider the patient's previous surgical history as this may provide a cause of ADH. Patients can present with ADH in a variety of ways. Respiratory, abdominal, and in some cases, cardiac symptoms are predicted.[30] The pressure effect from the abdominal organs in the thorax can result in shortness of breath and chest pain. Abdominal symptoms may also be present, including recurrent abdominal pain, postprandial fullness, vomiting, and obstructive gastrointestinal symptoms.[23] In some spontaneous cases, the DH may remain asymptomatic, only revealed incidentally upon imaging studies. Examination of the patient may reveal the scaphoid abdomen, absence of breath sounds over the lower chest area, with bowel sounds being audible.[31]

Evaluation

Imaging is vital for the diagnosis of an acquired diaphragmatic hernia. Various imaging modalities are used to diagnose or aid the diagnosis of a diaphragmatic hernia, including chest radiographs, ultrasonography, and magnetic resonance imaging, with computed tomography (CT) being the modality of choice.[31]

In patients with equivocal diagnosis, diagnostic laparoscopy or thoracoscopy are recommended. Moreover, open surgical exploration has been introduced to diagnose highly suspicious cases with equivocal imaging results. 

The diagnostic measures and required evaluations for congenital CDH have been classified into two main categories of pre and post-natal. Prenatal diagnosis in up to 60% of neonates with CDH is described by routine antenatal ultrasound screening during 18 to 22 weeks of gestation. Non-specific sonographic findings, including polyhydramnios or hydrops, are predicted in antenatal ultrasonography. However, the presence of abdominal organs in the fetal chest would characterize the diagnosis of CDH. Large diaphragmatic defects will optimize the diagnostic potential of the sonography.[32][33]

Left-sided CDH: the presence of a heterogeneous lesion in the left hemithorax and right mediastinal shift characterizes the prenatal left-sided CDH. The heterogeneous mass implies the herniated intestines. The fluid within the mentioned mass and, more importantly, peristalsis assist in differentiating CDH from other pre-natal intrathoracic lesions. The other diagnostic marker of congenital left-sided CDH is the absence of the stomach in the abdominal cavity. The displaced stomach is usually identified close to the left pericardial border or in the posterior cardiac space. Homogeneous hypoechoic mass in the chest close to the heart implies the herniated liver, and the intrahepatic vascular anatomy can be further characterized by Doppler sonography.[34]

Right-sided CDH – the presence of a homogeneous mass in the right chest suggests the right-sided CDH. The herniated liver may or may not cause the left mediastinal shift. The sonographic appearance of the liver is quite similar to the lungs and, therefore, may not serve as a reliable diagnostic marker. [35] The presence of pleural fluid and intestines are other potential characteristics of the right-sided CDH. It should be noted that the cardiac left shift serves as a more reliable marker to differentiate the right-sided CDH. 

Postnatal —Any term infants presenting with symptoms of respiratory distress should be evaluated for CDH. Chest radiography indicating herniation of the abdominal organs (usually intestines characterized by air- or fluid-containing structures) into either the right or left hemithorax with minimal visible aerated lung on the affected side suggests the diagnosis of CDH.[36] Further evidence supporting the diagnosis of  CDH includes the contralateral cardiac displacement, impression and mass effect over the contralateral lung, and reduced abdominal girth. To obtain the diagnosis, a chest x-ray with the placement of a feeding tube is recommended. Location of the feeding tube with the thoracic cavity or mediastinal left shift in right-sided CDH are predicted. Occasionally, the herniated liver is the only sign suggestive of the right-sided CDH. In the mentioned scenario, the presence of a large right thoracic solid mass without the normal abdominal shadow supports the diagnosis of right-sided CDH.[37]

Treatment / Management

Treatment of acquired diaphragmatic hernia in the acute setting requires appropriate patient resuscitation followed by surgical correction.[2] Typically, the procedure will use an open abdominal approach, and the repair accomplished by primary closure.[18] In cases where primary closure with non-absorbable sutures is not possible because of the size of the defect, then mesh repair may be an alternative.[23] If the diagnosis is delayed, a thoracic approach is generally preferred to reduce viscera-pleural adhesions and intra-thoracic visceral perforation.[23] It may be appropriate in some delayed cases to use a combined thoracic-abdominal approach. A laparoscopic approach may be feasible and an option for repair-dependent upon experience.[18]

Acquired diaphragmatic hernia (ADH) following trauma: pre-operative antibiotic therapy with first-generation cephalosporins is recommended. Moreover, in patients with high suspicion of synchronized intestinal trauma, antibiotic therapy to cover the anaerobes. In patients with greater than 1500 blood loss, and in the uncommon circumstances of prolonged surgery for greater than 2 to 3 hours, prophylactic antibiotic therapy should be repeated.

Following adequate primary resuscitation, a long-midline laparotomy incision from the xiphoid to the pubis is used. Primary evaluation of the four quadrant abdominal cavities and retroperitoneum should be undertaken. Bleeding and gastrointestinal spillage control should be prioritized. According to some literature review, in a selected group of patients with documented pure traumatic diaphragmatic injuries without other organ injuries, a primary upper midline incision might be performed. However, extending the incision for an appropriate exposure in equivocal circumstances after laparotomy should be considered.[38]

A thorough evaluation of the diaphragmatic surface should be included during the primary abdominal evaluation. Accordingly, the falciform ligament should be ligated and divided. Downward hepatic traction will assist the improved right hemidiaphragm evaluation. Additional exposure with mobilizing the liver from the coronary ligaments has not been described. To optimize the left hemidiaphragm visualization, gastric and splenic traction should be undertaken. The diaphragmatic central tendon and adequate firm attachments to the lumbar vertebrae should be confirmed. 

In the presence of abdominal visceral herniation, gentle reduction to the abdominal cavity should be undertaken. In rare circumstances, splenic injury during the reduction could complicate the procedure. In these selected cases, a meticulous extension of the defect is recommended. 

Chronic herniations differ from acute traumatic cases, where a hernia sac and severe dense adhesions are predicted. The hernia sac should be dissected, followed by the abdominal visceral reduction. It should be noted that any inadvertent injury, including serosal injuries, should be repaired promptly. 

 Next, the bulk of the trimmed diaphragmatic edges is held with Allis clamps. The edges are retracted caudally to allow adequate and versatile exposure, along with avoiding inadvertent injuries to the intra-thoracic organs. Thorax should be completely examined to ensure a bloodless, clean field. In case of any contamination, copious irrigation to avoid the risk of later empyema is recommended.[39]

The diaphragmatic repair is then undertaken with either permanent or absorbable sutures. The repair with both running and interrupted fashions has been described.

Minimally invasive approach: For patients with an isolated diaphragmatic injury, laparoscopic repair should be considered. However, in patients, with a positive surgical history and potential for severe dense adhesions, the left upper quadrant 3 cm below the costal margin may preferably be avoided.

Use of mesh —using mesh repair should not be considered the standard repair method. However, in uncommon circumstances where the primary repair is not quite feasible considering a significant tissue loss, using a mesh might be considered. In these patients, nonabsorbable prosthetic materials (including, polytetrafluoroethylene, and polyethylene) can be applied. Importantly, in the presence of GI spillage and contamination, adequate abdominal irrigation and autologous flaps are recommended. The latter flaps are provided using either omental or latissimus dorsi flaps.[40]

Differential Diagnosis

There is a broad range of differential diagnoses for ADH considering the variation in presentation and the variety of symptoms associated with it. Before imaging, a diaphragmatic hernia is unlikely to be high up the differential list for causation of the patient's symptoms, except perhaps in cases associated with trauma. After imaging, an alternative diagnosis that should merit consideration is metastasis, particularly with small defects.[30] Congenital causes of a diaphragmatic hernia should always be a consideration, particularly when trauma has not occurred previous to the presentation.[41]

Prognosis

If the clinician misses the diagnosis of acquired diaphragmatic hernia then there is a substantial risk of death; this can be due to lung compression with respiratory failure, vascular compromise with gastric or intestinal infarction, or perforation.[42] There is a documented variable risk in surgical mortality for diaphragmatic repair depending on concomitant injuries between 5 to 50%.[2] Generally, the outcomes following correction are good, with recurrence levels being low.[2]

Complications

Many potential complications can result from an acquired diaphragmatic hernia. Complications reported include diaphragmatic rupture, acute obstructive symptoms, respiratory failure incarceration, strangulation, and cardiac tamponade.[42][43] Delayed diagnosis would result in irreversible complications related to prolonged herniation. Accordingly, strangulation of abdominal viscera and life-threatening intestinal obstruction, perforation, and necrosis are predictable.

Deterrence and Patient Education

Most cases of acquired diaphragmatic hernia occur in emergencies following trauma; in these situations, surgery is life-saving. If possible, consent for surgery should be obtained with an explanation of the potential complications from surgery. These should be balanced with the complications including death if the surgery is not carried out.

Enhancing Healthcare Team Outcomes

Acquired diaphragmatic hernia is a serious condition which requires urgent surgery in the majority of cases. Imaging is vital for diagnosis however may be difficult to interpret particularly with additional damage from trauma, discussion between radiologist and surgeons is essential to enhance decisions in treatment. There is no consistent and recommended approach to surgery, with a variety of different methods and options being available. Typically, the repair will be carried out by general surgeons. However, if there is a delay in diagnosis, a thoracic approach may be required, and communication with the cardiothoracic surgeons can be crucial. Acquired diaphragmatic hernia is rare, so information regarding treatment meaning case studies may be vital in aiding with complicated cases in determining surgical approach (level 5).