What are the layers of the abdominal wall encountered during herniotomy?

Layers of the Abdominal Wall Encountered During Herniotomy

During a herniotomy, surgeons encounter multiple layers of the abdominal wall, with mass closure (including all layers except skin) being the preferred technique over layered closure in emergency settings due to its speed and similar outcomes. 1, 2

Standard Anatomical Layers (From Superficial to Deep)

1. Skin
2. Subcutaneous tissue/Superficial fascia
3. External oblique muscle/aponeurosis
4. Internal oblique muscle/aponeurosis
5. Transversus abdominis muscle/aponeurosis
6. Transversalis fascia
7. Preperitoneal fat
8. Peritoneum

Surgical Approach Considerations

Midline Approach

When performing a midline laparotomy, the layers encountered are:

• Skin
• Subcutaneous tissue
• Linea alba (fusion of anterior and posterior rectus sheaths)
• Preperitoneal fat
• Peritoneum

Paramedian Approach

When using a paramedian incision, the layers are:

• Skin
• Subcutaneous tissue
• Anterior rectus sheath
• Rectus abdominis muscle
• Posterior rectus sheath
• Preperitoneal fat
• Peritoneum

Closure Techniques and Recommendations

Mass Closure vs. Layered Closure

• Mass closure includes all layers of the abdominal wall except the skin in a single bite
• Layered closure involves closing more than one separate layer of fascial closure
• Mass closure is preferred because it is faster and shows no difference in incisional hernia rates or wound complications 1

Peritoneal Closure

• Separate closure of the peritoneum during abdominal wall closure is not recommended 1, 2
• No short-term or long-term benefit has been demonstrated for peritoneal closure
• Closure of the peritoneum involves additional operating time and suture material without apparent benefit 1

Suture Technique

• A suture-to-wound length ratio (SL/WL) of at least 4:1 is recommended for continuous closure of midline abdominal wall incisions 1
• "Small bite" technique is suggested to prevent incisional hernia and wound complications 1

Advanced Reconstruction Techniques

For complex hernias or recurrent cases, additional techniques may be employed:

1. Component Separation Technique (CST)

   • Enlargement of the abdominal wall surface by translation of muscular layers
   • Useful for large midline abdominal wall hernias 1

2. Transversus Abdominis Muscle Release (TAR)

   • Involves developing the retromuscular space laterally to the edge of the rectus sheath
   • Posterior rectus sheath is incised to expose the medial edge of the transversus abdominis muscle
   • The muscle is divided, allowing entrance to the space anterior to the transversalis fascia 3

3. Herniorrhaphy Lamination Technique

   • Uses local musculofascial flaps inspired by composite laminates
   • Primary fascial reapproximation is reinforced with additional laminated musculofascial layers 4

Common Pitfalls and Caveats

1. Avoid excessive tension during closure to prevent recurrence and wound complications
2. Do not close the peritoneum separately as it increases operating time without benefit 1, 2
3. Avoid bridging meshes when possible as they often result in bulging or recurrences 1
4. Consider the setting (elective vs. emergency) when choosing closure technique
5. Be aware of high-risk patients for incisional hernia development (diabetes, chronic pulmonary disease, smoking, obesity, immunosuppression, surgical site infection)

Understanding these anatomical layers and following evidence-based closure techniques are essential for successful herniotomy procedures and prevention of complications such as incisional hernias.