Ventral hernias are bulges that occur through defects in the abdominal wall. Incisional hernias typically refer to hernias that occur on the abdominal wall following a previous surgical incision. These may occur at any incision that is performed on the abdominal wall but more commonly occur at incisions through the linea alba. Surgeons are often asked to evaluate patients with incisional hernias are they can often be symptomatic to patients. Typically patients complain of a bulging at the site of the incision/hernia and in some cases can have associated pain. Patients with incisional hernias are also at risk for incarceration and strangulation, and the exact risk is typically small and patient and hernia dependent.
Incisional hernias occur after abdominal operations and result from a breakdown of fascial closure. Despite advancements in techniques for abdominal wall closure the incisional hernia rate following laparotomy is as high 15% to 20%. Although research is ongoing for the ideal closure methods to prevent incisional hernias, and recent guidelines have been published, surgeons are still often faced with incisional hernias and how to repair them.
The exact pathophysiologic mechanism for development for an incisional hernia remains unknown and is multifactorial. Technical factors, including those relating to suturing techniques of the fascia, and patient factors contribute to the occurrence of an incisional hernia. Postoperative wound infections significantly increase the likelihood of the development of an incisional hernia as well as not achieving a suture to wound length ratio of greater than 4:1.
Incisional hernias often present as a protrusion of the abdominal wall at the site of a previous incision. This is typically more pronounced when the abdomen is straining. The patient often will complain of a bulge or lump at the site on his abdomen and symptoms can range from no symptoms to pain and in some cases symptoms of bowel obstruction in cases of incarcerated or strangulated hernias. Physical exam involves abdominal palpation which will typically be able to diagnose the hernias in most cases. Although most cases of an incisional hernia may be diagnosed with a history and physical, imaging is sometimes warranted in complex cases and typically involves Computed Tomography (CT) scanning.
History and physical exam will allow for diagnosis of incisional hernias in the vast majority of cases. In cases of occult hernias, either small incisional hernias or hernias in obese patients, sometimes further workup with imaging is warranted. The computed tomography (CT) scan is the most commonly used method to diagnose an incisional hernia and can be useful in complex cases as well in helping plan operative management. Ultrasound techniques have also been described for evaluation of abdominal wall hernias (Dynamic Ultrasonography Assessment for Hernia-DASH). MRI can also be used to assess abdominal wall hernias but are less commonly used and is institution dependent.
Treatment strategies for an incisional hernia include watchful waiting and surgical repair. Although watchful waiting may be appropriate in select cases, the majority of incisional hernias will likely need surgical repair. Several techniques have been described for repair of incisional hernias. In general, in symptomatic patients that are medically fit should have surgery. Open, laparoscopic, and robotic techniques have been described to repair incisional hernias and must be tailored to the patient and hernia characteristics. In general, the mesh should be used to repair the majority of incisional hernias as they reduce the rate of recurrence compared to primary suture repair. Several different mesh prostheses are available. They range from synthetic to biologic meshes. Bioabsorbable meshes should be tailored to the individual clinical scenario. In general, laparoscopic and open techniques for incisional hernia repair have similar outcomes except for the decreased wound infection rate seen in laparoscopic repairs. Many of the techniques to repair an incisional hernia require specific knowledge of the abdominal wall anatomy and function including the neurovascular anatomy. Mesh may be placed intra-abdominally, in the preperitoneal or retrorectus space (retromuscular) or as on onlay. In general, the fascial closure should be performed and the closure augmented with mesh. If fascial closure cannot be achieved secondary to tension, multiple different component separation techniques have been described. The most common component separation techniques include incising the external oblique, dividing the posterior rectus sheaths, and division of the transversus abdominis (transversus abdominis release/TAR).
Prevention of an incisional hernia is a major topic for hernia surgery currently. There are several principles surgeons should be aware of to help prevent an incisional hernia. First, if applicable, off-midline incisions have been recommended as there is some evidence that these incisions result in decreased incidence of an incisional hernia. Typically running closure with a slowly absorbing monofilament suture is recommended as this results in the most efficient closure. A suture to wound length ratio less than 4:1 has been shown to increase incisional hernia rates compared to achieving greater than 4:1, so surgeons should be aware of their technique. Recently, the traditional 1 cm bite and 1 cm advance technique for fascial closure have been challenged with two well-done prospective studies showing a decreased incisional hernia rate when using 5 mm bites and 5 mm advances. In some high-risk patients and cases, the incisional hernia rate is extremely high despite the adequate closure. Open abdominal aortic aneurysm (AAA) repair and formation of permanent colostomies are associated with high incisional/parastomal hernia rates and some have advocated prophylactic mesh augmentation in these cases. Further study into the use of prophylactic mesh for reduction of an incisional hernia requires further study.
Incisional hernia repair has similar complications to other types of hernia repair. In general, surgical site infection and occurrences, as well as recurrence rates remain common complications. Many incisional hernia repair cases have significant adhesions from previous surgery and laparoscopic access for laparoscopic ventral hernia repair and adhesiolysis whether open or laparoscopic remains important parts of this procedure to help prevent enterotomies. Recurrences after repair of incisional hernias are more frequent than most surgeons would like, and it has been reported the more times the patient has had a hernia repair and failed, the harder those are to fix. Therefore, a solid, durable repair is warranted at the time of the first operation.