Diaphragmatic Hernia - General Surgery

Anatomy of the Diaphragm - Sites of Herniation

• 1 - Sternocostal foramen of Morgagni (anteriorly)
• 2 - Esophageal hiatus (centrally)
• 3 - Bochdalek foramina (posterolaterally)

1. Hiatal and Paraesophageal Hernias

Classification

Etiology and Pathophysiology

• Type I: Age-related deterioration of the phrenoesophageal membrane, combined with positive intra-abdominal pressure and traction from esophageal shortening during swallowing
• Paraesophageal types: Posterior phrenoesophageal ligament preserved in pure Type II (GEJ stays put); entire stomach can herniate in severe cases

Epidemiology

• Prevalence 14-84% depending on population and diagnostic method
• More frequent in GERD patients
• Symptomatic paraesophageal hernias most common in middle-aged to older adults

Clinical Features

• Type I (sliding): Often asymptomatic; main significance is association with GERD. Symptoms: heartburn, regurgitation, dysphagia
• Type II-IV (paraesophageal): Postprandial chest/epigastric pain, dysphagia, early satiety, dyspnoea. Can cause anaemia (Cameron ulcers from mucosal ischaemia at the diaphragmatic ring)
• Complications: Gastric volvulus (organoaxial or mesenteroaxial), incarceration, strangulation, perforation, acute bleeding

Diagnosis

• Barium UGI study: First-line for diagnosing type and anatomy
• CT scan: Preferred for Type IV (reveals colon/pancreas that barium may miss); key questions: Is GEJ above hiatus? Is stomach above GEJ?
• Endoscopy (EGD): Dynamic assessment, retroflex view confirms hernia

Management

1. Reduce herniated contents from chest back into abdomen
2. Excise/reduce the hernia sac
3. Close the hiatal defect with non-absorbable sutures (cruroplasty); biological mesh reinforcement for large defects
4. Fundoplication (Nissen or Dor) to restore LES competence and prevent recurrence
5. Gastropexy or gastrostomy tube (as pexy) for 2 weeks to allow stomach to mature to abdominal wall - reduces recurrence
6. Collis-Nissen procedure when esophageal shortening is present (a stapler creates a neo-esophagus from proximal stomach, parallel to esophagus over a bougie)
7. In obese patients (BMI >35 kg/m²), Roux-en-Y gastric bypass may be favored

2. Congenital Diaphragmatic Hernia (CDH)

Pathophysiology

• Pulmonary hypoplasia (mechanical compression + genetic causes)
• Persistent pulmonary hypertension (PPH)
• Cardiac defects
• Gastroesophageal reflux
• ~50% have additional anomalies

Anatomy

Prenatal Diagnosis and Prognosis

• Diagnosed antenatally by ultrasound (hallmark: diaphragmatic defect with bowel in chest)
• Lung-to-head ratio (LHR): contralateral lung area/head circumference
  • LHR <1: poor prognosis
  • LHR >1.4: nearly 100% survival
• O/E LHR (observed-to-expected LHR): <25% = <20% survival
• Liver position ("liver up" in chest = worse prognosis)
• Total fetal lung volume by MRI is also used

Prenatal Intervention - Fetal Endoscopic Tracheal Occlusion (FETO)

• Tracheal occlusion causes accumulation of fetal lung fluid, stimulating lung growth
• TOTAL trials (randomized): For severe CDH (O/E LHR <25%) - FETO balloon placement at 27-29 weeks significantly improved survival (40% FETO vs. 15% expectant care); study stopped early for efficacy
• For moderate CDH - FETO showed no survival benefit at the tested gestational age

Neonatal Stabilization (Postnatal Management - Pre-repair)

1. Immediate intubation and mechanical ventilation (avoid bag-mask ventilation)
2. Nasogastric tube decompression
3. Gentle ventilation - permissive hypercapnia; goal: pH >7.2, pre-ductal SpO2 85-95%
4. High-frequency oscillatory ventilation (HFOV) may help
5. Treat pulmonary hypertension: inhaled nitric oxide, prostaglandin E1, milrinone, inotropes
6. ECMO/ECLS for refractory cases (severe cardiac dysfunction)
7. Repair offered only once pulmonary circulation stabilises

Surgical Repair

• Approach: transabdominal or transthoracic, open or minimally invasive (laparoscopic/thoracoscopic)
• Small defects: closed with non-absorbable sutures (primary closure)
• Large defects: require a conical Silastic or GOR-TEX patch (prosthetic)
• A hernia sac may be present and can be removed or plicated

Prognosis

• Survival has improved to 65-90% with modern management
• Ongoing morbidity: pulmonary hypertension, recurrent GERD, neurodevelopmental issues

3. Traumatic Diaphragmatic Hernia

Epidemiology

• Overall incidence ~0.46% (NTDB data)
• Penetrating trauma accounts for ~67% of injuries
• Blunt trauma (motor vehicle accidents, ~75% of blunt mechanism) causes higher mortality (19.8% vs. 8.8% for penetrating) due to severe associated injuries
• Left hemidiaphragm injured in ~75% of cases - liver protects the right

Mechanism

• Blunt: Rapid increase in intra-abdominal pressure causes a "blow-out" of diaphragmatic tissue
• Penetrating: Direct laceration by missile or knife

Natural History

AAST Grading

Diagnosis

• Chest X-ray: Intraabdominal viscera in chest (left-sided large defects); elevated or distorted hemidiaphragm; NGT in chest
• CT scan: Sensitivity up to 78%, specificity 72-100%; shows visceral herniation, diaphragm thickening/elevation/defect; still challenging for stab wounds
• Laparoscopy: Recommended diagnostic and therapeutic tool - particularly for penetrating thoracoabdominal trauma (reduces missed injuries vs. CT alone)
• VATS: Alternative for visualizing the diaphragm

Right hemidiaphragm penetrating injuries rarely present in a delayed fashion - may be considered for nonoperative management in stable patients without radiographic signs.

Surgical Repair

1. Debride non-viable tissue at the injury site
2. Primary closure with single layer of non-absorbable sutures (full-thickness diaphragm) - most defects can be approximated because of diaphragm redundancy/pliability
3. Watch for significant bleeding from phrenic artery branches at tear edges
4. Large tissue loss with inability to achieve primary closure: prosthetic mesh (non-absorbable synthetic in clean fields; avoid if contaminated)
5. Peripheral detachment: re-attach diaphragm to thoracic wall

Summary Comparison Table

• Sabiston Textbook of Surgery, 21st ed. - Diaphragmatic Conditions (Chapter 117), Fetal Surgery (Chapter 118), Diaphragmatic Injuries (Chapter 36)
• Sleisenger and Fordtran's Gastrointestinal and Liver Disease - Chapter 27: Diaphragmatic Hernias
• Bailey and Love's Short Practice of Surgery, 28th ed. - Chapter 18
• Fischer's Mastery of Surgery, 8th ed.