What is an incisional hernia?
An incisional hernia occurs when there is a hole in the deep layers of an old surgical scar. The deep stitches give way and the muscle layers separate. As they do this, a piece of bowel or fat from inside the abdominal cavity may protrude through this hole. A hernia will appear as a lump under or to the side of the surgical scar and become more prominent when standing up. The lump may disappear or become smaller when lying down. It may be barely noticeable or they may protrude and hang down a long way when standing up.
What causes an incisional hernia?
There are many factors that contribute.
- Wound infections after surgery
- Many operations via the same incision
- Operations for severe pancreatitis
- Colostomy or stomas
- Long term prednisone or immunosuppression drugs
What problems can incisional hernias cause?
Incisional hernias do not get better without treatment and will typically grow larger over time. Hernias cause discomfort and sometimes pain. Patients will complain of a dragging sensation or a squelching noise as the bowel moves around in the hernia. It may be difficult to have a bowel movement without holding the hernia. The feared complication of incisional hernia is when a piece of bowel becomes trapped, loses its blood supply and dies. This is a surgical emergency and can be life threatening. Symptoms of this include sudden, extreme pain in the hernia, inability to push the hernia back in, vomiting or redness over the hernia. Should this occur, you should go immediately to the Emergency Department.
How are incisional hernias treated?
Incisional hernias can be extremely difficult to repair because the tissues we are working with are stretched thin and have very little strength. Each case is assessed on an individual basis. There may have been previous attempts made at repairing these hernias and this can make the surgery more complicated. A good way to think about fixing a hernia is to liken it to patching a hole in a plaster wall. The edges of the hole are difficult to pull together, so a patch or “mesh” is placed behind the defect. This reinforces the weakened tissue and muscle. The mesh can be made of several different types of material. (see separate section about mesh) The mesh becomes incorporated into the body and adds extra strength. The mesh can be used in a variety of ways but it is usually placed against the muscle inside the abdominal cavity. The weakened muscle layer is then pulled closed over the top of the mesh. These tightened layers will eventually weaken again and the mesh is there to bridge the gap as they separates.
Incisional hernias can be repaired in two different ways.
- Open technique – an incision is made though the old scar and the contents of the hernia are returned to the abdomen. Finally a mesh is placed across the hole.
- Laparoscopic or keyhole technique – smaller incisions are made around the periphery of the abdomen and the hernia is repaired from inside the abdominal cavity using a mesh.
In either technique, the mesh may be fixed in place using dozens of surgical tacks and stitches. These tacks may be permanent and easily visible on a scan or they might be dissolvable.
Sometimes a combination of both keyhole or open techniques are used. Laparoscopic surgery seems to have a lower rate of wound infection but a higher risk of bowel injury. This is because the scarring in the abdomen can be significant after previous surgery. Bands of tissue called adhesions form after all abdominal surgery and this might trap loops of bowel in a spiderweb of tissue. This tissue has to be released during the hernia repair and this might be more difficult in keyhole techniques. It is easy to miss small holes made in the bowel during the dissection. Laparoscopic incisional hernia repair can also have a poorer cosmetic and functional result because the abdominal wall muscles are not able to be pulled together as well as the open technique.
Both techniques have their pros and cons and are acceptable. Incisional hernia surgery is carefully tailored to the individual. Post operative recovery and pain is similar with both techniques and there is no big advantage to keyhole surgery in this respect.
Diagram illustrates how the mesh is inserted behind the muscle layer and the muscles are sewn together over the mesh.