A hernia occurs when an internal part of the body squeezes through a weak spot in the wall of the cavity, which usually contains it.

Surgical correction of hernias is currently the major operation most frequently performed by general surgeons in the United States, is the and the second most common abdominopelvic surgery after cesarean section. Unfortunately, complications from surgical repair such as hernia recurrence, post-operative fluid collection, and complications related to prosthetic materials can occur in up to 20 per cent of cases.

TYPES OF ABDOMINAL WALL HERNIAS

There are many different types of abdominal wall hernias. Inguinal hernias occur in the groin and are the most common type of abdominal wall hernia. They are more common in males than in females. Femoral hernias are also found in the groin and are more common in females. Ventral hernias include all hernias in the front and side of the abdominal wall. Umbilical hernias are the most common type of ventral hernia. There are many other types of abdominal wall hernia, including lumbar, incisional, and even less common types.

Radiology is important for the identification and localisation of a hernia, as well as the evaluation of complications due to the hernia itself or treatment of the hernia. Imaging helps to minimise the time it takes to repair a hernia or its complication, because physical examination alone may not be reliable.

COMPLICATIONS OF ABDOMINAL WALL HERNIAS

The most common complications of abdominal wall hernias are bowel obstruction secondary to the hernia, incarceration and strangulation. After adhesions, which form after surgery or inflammatory conditions, abdominal wall hernias are the second-leading cause of bowel obstruction. Incarceration refers to a hernia which cannot be pushed back manually. Strangulation occurs when the blood supply to bowel is affected and ischemia results.

Hernias may be caused by trauma or there may be trauma to a pre-existing hernia. Interestingly, seat belt use, which exposes the wall musculature to full deceleration forces, increases the risk for traumatic hernias. Seat belts save lives though, so wear them.

Surgical procedures used to repair abdominal hernias range from open or laparoscopic suture repair to the use of mesh. Tension-free mesh repair is the standard surgical technique for the majority of abdominal wall hernias. Computerised tomography (CT) is excellent for detecting the complications of surgical repair.

Hernia recurrence is the most common complication after hernia repair, usually occurring two to three years after surgery. Other complications include fluid collections, infections and mesh-related problems.

Fluid collections occur frequently in the period immediately after surgery. These collections usually contain serous fluid (seroma) or blood products (hematoma), and their formation depends both on the surgical technique and the type of mesh used.

Most seromas resolve by themselves within 30 days. A radiologist may be asked to aspirate the collection if it persists for more than six weeks, steadily grows in size, produces symptoms, or is suspected to be infected. Computerised tomography or ultrasound help identify fluid collections, differentiate them from hernia recurrence, guide aspiration attempts, and confirm their resolution.

Infected collections occur in a small number of patients after surgery (one to five per cent). They tend to occur in older female patients, especially after surgical repair of incarcerated or strangulated hernias. CT or ultrasound, with the aid of blood tests and physical examination, can help to identify an infected location and pinpoint how deep it is located in the abdomen.

Complications may occur with the mesh itself. Inflammatory reactions may lead to fibrosis of the tissue surrounding the mesh. Mesh shrinkage can occur. Adhesions may occur within the abdomen increasing the risk of small bowel obstruction. Less commonly, meshes can detach and migrate within the abdominal wall.

No swelling of the anterior abdominal wall should be ignored. Hernias are correctible and prompt action can prevent serious complications down the road. The radiologist is able to help to identify hernias and their complications, as well as treat some of the complications of surgery.

Dr Duane Chambers is a consultant radiologist and founding partner of Imaging and Intervention Associates located at shops 58 and 59 Kingston Mall, 8 Ocean Boulevard. He may be contacted through the office numbers 618-4346 or 967-7748.