An incisional hernia refers to a hernia occurring at the site of a previous abdominal surgical incision. It ranks as the third most common type of external abdominal hernia. For incisions that achieve primary healing, the incidence of incisional hernia is typically below 1%. However, if the incision becomes infected, the incidence can increase to 10%, and in cases where the wound dehisces, it may rise to as high as 30%.
Among common surgical abdominal incisions, the highest risk of incisional herniation is associated with midline incisions through the rectus abdominis. The lower abdomen, where the posterior sheath of the rectus abdominis is incomplete, is particularly vulnerable. Median and paramedian incisions follow in frequency.
The higher incidence of incisional hernias in vertical abdominal incisions is influenced by several factors. Other than the rectus abdominis muscle, most layers of the abdominal wall, including muscle fibers, fascia, and sheaths, run transversely. Vertical incisions necessarily disrupt these transverse fibers. During closure, sutures are more likely to slide between fibers, and the tension from transverse pulling on these tissues often results in wound dehiscence. While vertical incisions may preserve the robust rectus abdominis muscle, they can weaken the area by cutting intercostal nerves, thereby reducing the muscle's strength.
In addition to these anatomical factors, surgical technique plays a critical role in the development of incisional hernias. The most common contributing factor, accounting for approximately 50% of cases, is infection of the incision, which compromises the integrity of the abdominal wall tissues. Other causes include prolonged placement of drainage tubes, overly lengthy incisions that sever excessive intercostal nerves, inadequate closure of the abdominal wall, and improper handling during suturing, such as excessive tension caused by forced approximation of the wound edges when anesthesia is insufficient. Postoperative factors, such as significant abdominal distension or respiratory complications leading to intense coughing and sudden intra-abdominal pressure surges, can result in dehiscence of the deeper layers of the incision, contributing to hernia formation. Poor wound healing is another major factor, which can arise from various reasons, such as hematoma formation at the incision site, obesity, advanced age, diabetes, malnutrition, or the use of certain medications, such as glucocorticoids.
The main symptom of an incisional hernia is progressive bulging at the site of the abdominal incision, accompanied by a palpable mass. The mass typically becomes more prominent when standing or straining and reduces in size or disappears when lying down. Larger hernias may cause abdominal discomfort, including a sensation of pulling, loss of appetite, nausea, constipation, and dull abdominal pain. Many incisional hernias lack a complete hernial sac; their contents often adhere to the extraperitoneal tissues of the abdominal wall, resulting in irreducible hernias, sometimes associated with partial bowel obstruction.
Examination often reveals a bulge or mass at the incision site. Smaller hernias may have a diameter of just a few centimeters, while larger ones can reach 10–20 cm or even greater in size. In some cases, hernia contents extend to lie just beneath the skin, allowing observation of intestinal loops and peristaltic waves. On palpation, bowel gurgling sounds may be audible. After reduction of the hernial contents, the edges of the hernial ring formed by the defect in the abdominal muscles are often palpable. Hernias caused by weakness of the abdominal muscles resulting from intercostal nerve injury may exhibit local bulging but do not produce a well-defined mass or distinct hernial ring. The size of the hernial ring in incisional hernias is generally large, making incarceration relatively rare.
For smaller incisional hernias, direct suture repair may be performed. The key points of the procedure include exposing the hernial ring, carefully dissecting the layers of abdominal wall tissue along its edges, reducing the hernial contents, and approximating the edges of the hernial ring under tension-free conditions, followed by layer-by-layer suturing of healthy abdominal wall tissues.
For larger hernias, extensive atrophy of abdominal wall tissues may make tension-free closure of the hernial ring difficult. Even if closed under tension, the likelihood of postoperative recurrence remains high. In such cases, the use of repair materials such as mesh or autologous fascia grafts is recommended.
In recent years, laparoscopic repair of incisional hernias has been increasingly used in clinical practice. The primary advantage of laparoscopic repair is the more convenient and efficient placement of mesh, as well as the ability to directly visualize the extent of adhesions and detect concealed defects. Compared to conventional open surgery, laparoscopic repair offers significant improvements in recovery, with lower incidences of surgical wound complications, mesh infections, and hernia recurrence. However, the indications for laparoscopic repair must be stricter than those for open surgery. Inexperienced surgeons may encounter complications such as intestinal injury, which can increase the risks of intra-abdominal infection and mortality.