Abdominal wall hernia is the most common complication following laparotomy, reaching figures as high as 50% in some studies.
It is also the most common indication for reoperation, in a 3:1 margin over bowel obstruction.
There are a variety of options for a ventral hernia repair, with the most traditional methods resulting in very high recurrence rates.
In the 1990s, Ramirez and colleagues described the creation of myofascial advancement flaps as a method to repair ventral hernias. This first component separation technique had recurrence rates of 10% to 22%, but considerable morbidity, leading to development of alternative methods and improvements to reduce it.
Posterior component separation techniques are based on the River-Stoppa-Wantz retrorectus repair, regarded as the gold standard method for ventral hernia repair by the American Hernia Society in 2004. Recurrence rates of this techniques can be as low as 3%.
The anterior abdominal wall is a hexagonal area defined superiorly by the costal margin and xiphoid process; laterally by the midaxillary line; and inferiorly by the symphysis pubis, pubic tubercle, inguinal ligament, anterior superior iliac spine, and iliac crest.
Layers of the anterior abdominal wall include skin, subcutaneous tissue, superficial fascia, deep fascia, muscle, extraperitoneal fascia, and peritoneum.
The superficial fascia of the abdominal wall consists of a single layer above the umbilicus, comprising the fused Camper and Scarpa fasciae.
Below the umbilicus, the superficial fascia consists of a fatty outer layer (Camper fascia) and a membranous inner layer (Scarpa fascia).
The deep fascial layers are composed by the rectus sheath in the midline and external oblique, internal oblique, transversus abdominis, and parietal peritoneum, laterally.
The rectus abdominis muscles originate from the pubic symphysis and pubic crest and insert on the anterior surfaces of the fifth, sixth, and seventh costal cartilages and the xiphoid processes. Laterally, the rectus sheath merges with the aponeurosis of the external oblique muscles to form the linea semilunaris.
The external oblique muscle is the most superficial and thickest of the three lateral abdominal wall muscles.
The internal oblique muscle is deep with respect to the external oblique muscle, and its aponeurosis splits medially above the arcuate line to form part of the anterior rectus sheath and part of the posterior rectus sheath.
The transversus abdominis muscle is the deepest of the three lateral abdominal wall muscles and courses in a horizontal direction.
Planning of a Component Separation Repair
Planning a ventral hernia repair, as in any other surgical intervention, focuses on 3 interdependent parts:
- The Patient and his or her comorbidities
- The condition: in this case, the Hernia and its characteristics
- The procedure and the materials needed
Patient evaluation begins with clinical history: it is important to know about previous operations. The physical exam is crucial to understand the location of the defect, its size and the number of the defects. A CT scan will complete the evaluation, helping to guide the intervention.
The type of mesh used depends on the potential for wound infection. A synthetic mesh is usually employed, with biologic mesh being reserved for high-risk patients. The ideal mesh is macroporous, about 30x30cm, and can be positioned as onlay, sublay or underlay.
Anterior and Posterior Component Separation Techniques
Whatever the technique chosen, antibiotic prophylaxis is given 1h prior to the incision The patient is placed in a supine position with abducted arms, the skin is disinfected with 2% chlorhexidine solution, and a foley catheter and a nasogastric tube are inserted.
The preferred incision is a generous laparotomy from the xiphoid to the pubic tubercle. Any residual mesh must be removed and care must be taken not to injure the bowel when entering the abdominal cavity.
The surgeon must proceed to the lysis of any adhesions to the abdominal and pelvic wall before starting the repair.
Anterior component separation (ACS) is based on the creation of lipocutaneous flaps, with or without preservation of the umbilicus, allowing for the positioning of an onlay mesh.
Posterior component separation (PCS) creates a retrorectus space, with or without transversus abdominis release, allowing for the positioning of a sublay mesh.
Postoperative Period and Results
Postoperative care involves pain control, dietary concerns, regulation of the drains, use of an abdominal binder, and mechanical and pharmacological venous thromboembolism prophylaxis.
Epidural catheters are recommended for all patients for about 3 to 4 days.
Diet must be regulated and patients should be kept nil per os until flatus is passed.
Drainage is usually kept until the output is less than 30mL per day.
An abdominal binder must be used in the immediate postoperative period and should last beyond discharge.
Wound complications are the main cause of morbidity after hernia repair. Surgical site infections rate can reach 41% in high-risk populations.
Pulmonary complications are responsible for severe morbidity.
About 20% of patients will suffer from this kind of complication. The key factor is prevention, which is based on respiratory physiotherapy, use of spirometer, adequate analgesia and standing in an upright position.
There have been many studies published regarding results of ventral hernia repair with component separation.
Mortality is very rare, with rates under 1%.
Wound complication is higher in anterior component separation, reaching 63% in some publications.
Posterior component separation has lower recurrence rates, and is superior to the other repair techniques described.