What is an incisional hernia An incisional hernia is a hernia in which the abdominal viscera protrude from an abdominal surgical incision. The incidence is higher in the lower midline abdominal incisions. The incidence is usually less than 1%, but incisional infections can occur in up to 10% of cases. Of the various abdominal incisions commonly used, the most frequent incisional hernia occurs through the rectus abdominis incision; it is more frequent in the lower abdomen because of the incomplete posterior rectus abdominis sheath. Incisional hernias occur less frequently in median and paramedian incisions because they do not damage the intercostal nerves; however, more incidences can occur in median incisions (especially in the upper abdomen) than in paramedian incisions because of the lack of strong abdominal muscle protection and poor blood supply in the median line. The etiology of incisional hernia The reason why incisional hernia is more common in longitudinal abdominal incisions is that, except for the rectus abdominis muscle, the fibers of all layers of abdominal wall muscles, fascia, sheath and other tissues are by and large transverse, and longitudinal incisions are bound to cut these fibers; when suturing these tissues, the sutures tend to slip between the fibers; and the sutured tissues are often subjected to transverse indexing force of the muscles and are prone to wound rupture. In addition, although the longitudinal incision does not sever the strong rectus abdominis muscle, its strength may be reduced because the intercostal nerves can be severed. In addition to the anatomical factors mentioned above, the most important one is the destruction of the abdominal wall tissue due to incisional infection (the resulting abdominal incisional hernia accounts for about 50% of all cases). Other conditions such as prolonged retention of drains, excessively long incision to the point of severing the intercostal nerves, poorly closed abdominal wall incision, poor anesthesia during surgery, and tissue tearing due to forced pulling of the wound edge during suturing can all lead to incisional hernia. A sudden increase in intra-abdominal pressure due to significant post-operative abdominal distension or pulmonary complications resulting in severe coughing can also cause the incisional lining to tear and incisional hernia to occur. In addition, poor wound healing is also an important factor, such as old age, poor nutrition, atrophy of the abdominal muscles, and obesity. Symptoms of incisional hernia The main symptom of an abdominal incisional hernia is the presence of a mass at the incision in the abdominal wall. The mass is usually more obvious when standing or exerting force, and shrinks or disappears when resting. In larger incisional hernias, there is a pulling sensation in the abdomen. This is accompanied by loss of appetite, nausea, and constipation. On examination, a mass can be seen at the incision scar, ranging from a few centimeters in diameter in small cases to 10-20 cm or even larger in large cases. Sometimes the content of the hernia can reach the subcutaneous area, and intestinal pattern or peristaltic waves can be seen and the gurgling sound of the intestinal canal can be felt on palpation. After the mass is repositioned, the edge of the hernia ring formed by the splitting of the abdominal muscle can mostly be felt. In incisional hernias, the hernia ring is usually wide, and intussusception rarely occurs. Differential diagnosis of incisional hernia Incisional hernia should be differentiated from abdominal wall bulge, the main difference being: incisional hernia is a defect in the abdominal wall; in abdominal wall bulge the abdominal wall is not defective, but weak, mostly caused by intercostal nerve injury in the abdominal wall. Ultrasound, CT and other examinations can help to differentiate the two. Treatment of incisional hernia is mainly surgical, but only in elderly and frail patients who cannot tolerate surgery or have a persistent cough that cannot be controlled can be bandaged with an elastic bandage. The principles of surgery include: ① excision of the incision scar; ② revealing the hernia ring and clearly dissecting the layers of abdominal wall tissue along its edges; ③ retrieving the hernia contents, pulling together the edges of the ring under tension-free conditions, and carefully suturing the healthy layers of abdominal wall tissue layer by layer, which can be strengthened by overlapping sutures if necessary. The above requirements are easy to achieve for small incisional hernias. For larger incisional hernias, because the extent of abdominal wall tissue atrophy is too large, it is difficult to pull together the healthy tissues without tension, and a built-in patch is needed to fill the defect in order to obtain a satisfactory repair. If the patch is forcibly pulled together under tension, even if it is barely sutured, recurrence is inevitable after all. Patch placement can be done either by open surgery, lumpectomy, or a combination of lumpectomy and open (also called hybrid surgery).