What is the appropriate evaluation and management of an elevated right hemidiaphragm on a chest radiograph?

Evaluation and Management of Elevated Right Hemidiaphragm

Obtain a contrast-enhanced CT scan of the chest and abdomen as the definitive diagnostic study when an elevated right hemidiaphragm is identified on chest X-ray, as this is the gold standard for determining the underlying cause with 87% specificity. 1, 2

Initial Diagnostic Approach

Chest Radiograph Assessment

• Chest X-ray is appropriate as the initial screening study but has significant limitations—normal radiographs occur in 11-62% of diaphragmatic hernias and injuries, making it unreliable for excluding pathology 1, 2
• Evaluate the shape and contour of the elevated hemidiaphragm on lateral view: a radius of curvature ratio (HH/APD) >0.28 suggests against paralysis and favors eventration 3
• Look for specific findings that indicate the etiology:
  • Diaphragmatic hernia: bowel gas pattern in thorax, air-fluid levels, mediastinal shift, or visible bowel loops 2
  • Pulmonary hypertension: right descending pulmonary artery >15 mm in women or >16 mm in men at the hilum (93% sensitivity, 88% specificity), main pulmonary artery >35 mm, or cardiac enlargement 4
  • Subdiaphragmatic pathology: soft tissue opacity with mass effect 1

Key Clinical History Elements

• Prior procedures: chest tube insertion, cardiac surgery, or thoracic operations can cause phrenic nerve injury leading to paralysis 1, 5
• Trauma history: blunt or penetrating chest/abdominal trauma raises suspicion for diaphragmatic rupture 1, 2
• Respiratory symptoms: dyspnea, orthopnea, or chest pain may indicate functional impairment 6, 7
• Risk factors for malignancy: lung cancer with mediastinal invasion can cause phrenic nerve dysfunction 1
• Female patients with prior pneumothorax surgery: consider catamenial pneumothorax with diaphragmatic fenestration and visceral herniation 8

Definitive Imaging Strategy

Contrast-Enhanced CT (First-Line Advanced Imaging)

Order CT chest and abdomen with both IV and oral contrast for nearly all cases of elevated right hemidiaphragm requiring further evaluation 1, 2

• Sensitivity: 14-82% for diaphragmatic hernias; Specificity: 87% 1, 2

• Critical CT findings to identify:

  • Diaphragmatic discontinuity or segmental non-visualization 1, 2
  • "Collar sign" (constriction of herniating organ at rupture level) 1, 2
  • "Dependent viscera sign" and "dangling diaphragm" sign 1, 2
  • Intrathoracic herniation of abdominal contents (liver, bowel, stomach) 1, 2
  • Bowel wall enhancement abnormalities indicating ischemia 2
  • Thickened or absent diaphragm segments 1

• IV contrast is mandatory to assess vascular perfusion and detect complications like bowel ischemia or strangulation 2

• Oral contrast enhances identification of anatomical landmarks and herniated bowel 2

Functional Assessment with Fluoroscopy

• Perform fluoroscopic sniff test when diaphragmatic paralysis versus eventration is the primary differential and CT shows no structural defect 3, 6, 7
• Interpretation criteria:
  • Paralysis: absent orthograde excursion with paradoxical motion on sniffing 6
  • Weakness: reduced or delayed orthograde excursion on deep breathing 6
  • Eventration: focal weakness with preserved motion in other segments 6
• Fluoroscopy may be unnecessary if lateral chest X-ray shape analysis (HH/APD ratio) clearly suggests eventration 3

Transthoracic Echocardiography

• Obtain echocardiography when pulmonary hypertension is suspected based on:
  • Enlarged pulmonary arteries on chest X-ray 4
  • Right heart enlargement 4
  • Clinical symptoms of dyspnea with risk factors for pulmonary hypertension 9
• Echocardiography has 85% sensitivity and 74% specificity for moderate-to-severe pulmonary hypertension 4

Alternative Imaging

• MRI: reserve for pregnant patients (after initial ultrasound) or when CT findings are inconclusive and additional soft tissue characterization is needed 1, 2
• Ultrasound: first-line in pregnant patients with suspected non-traumatic diaphragmatic hernia to avoid radiation 1, 2

Management Based on Etiology

Diaphragmatic Hernia (Traumatic or Non-Traumatic)

• Surgery is the treatment of choice for symptomatic diaphragmatic hernia 1
• Stable patients: laparoscopic approach is strongly recommended (1B evidence) 1
• Unstable patients: laparotomy approach (2C evidence) 1
• Repair technique: primary repair with non-absorbable sutures; for defects >3 cm, use mesh reinforcement (biosynthetic, biologic, or composite meshes preferred, 2C evidence) 1

Diaphragmatic Paralysis

• Treatment depends on symptom severity and underlying cause 6
• Options include:
  • Conservative management for asymptomatic or mildly symptomatic patients 6
  • Diaphragmatic plication for severe dyspnea or ventilator dependence 6, 5
  • Phrenic nerve stimulation in select cases 6

Pulmonary Hypertension

• Initiate workup per pulmonary hypertension guidelines if echocardiography confirms elevated pressures 9
• Address underlying causes (lung disease, left heart disease, chronic thromboembolic disease) 9

Subdiaphragmatic Mass or Pathology

• CT will delineate hepatic, adrenal, or other masses pushing the diaphragm upward 1
• Manage according to the specific pathology identified 1

Critical Pitfalls to Avoid

• Never rely on chest X-ray alone to exclude diaphragmatic hernia—11-62% of hernias have normal radiographs 1, 2
• Do not dismiss persistent ipsilateral chest pain after thoracic surgery as neuropathic pain without ruling out diaphragmatic fenestration and visceral herniation, especially in women with prior pneumothorax surgery 8
• Do not overlook malignancy as a cause of phrenic nerve dysfunction in patients with risk factors for lung cancer 1
• Avoid misinterpreting subpleural fat as pleural thickening; CT can differentiate these 1
• Do not assume eventration without functional assessment if the clinical picture suggests paralysis (recent surgery, trauma) 3, 6
• Chest X-ray is insensitive for mild pulmonary hypertension—proceed to echocardiography if symptoms suggest elevated pulmonary pressures despite normal-appearing vessels 4
• In post-bariatric surgery patients, maintain a low threshold for diagnostic laparoscopy even if CT is negative, as 40-60% of surgically confirmed internal hernias had negative CT scans 2