The midline incision provides the fastest and simplest approach making it a popular incision. It offers adequate exposure to any part of the abdominal cavity including the retroperitoneum. When speed is essential, it is clearly the incision of choice because it can be made and closed rapidly. It is almost avascular, allows for preservation of muscle fibers, and avoids nerve injury. It can be extended upward and downward the full length of the abdomen by curving the skin incision around the umbilicus (Fig. 2A). The incision is deepened through skin, subcutaneous fat, linea alba, properitoneal fat, and peritoneum. Properitoneal fat is abundant in obese individuals, and medium-sized vessels may be encountered. If the falciform ligament is encountered or is found interfering with exposure in the upper abdomen, it should be clamped, divided, and ligated. Upper midline incisions provide adequate exposure for most operations on the esophageal hiatus, abdominal esophagus (and vagus nerves), stomach, duodenum, gallbladder, pancreas, and spleen. Lower midline incisions provide good exposure for operations for the sigmoid colon and rectum, as well as all the pelvic organs.

When making vertical abdominal incisions, one should enter the peritoneum near the umbilicus to avoid injury to the bladder. Care must be exercised in opening the peritoneum to avoid injury to an underlying bowel loop, particularly when the bowel is distended in the setting of a bowel obstruction. A safe method is to pick up a fold of peritoneum with a pair of forceps, palpate it to ensure that no other structure has been caught up with it, and then carefully incise the raised fold with a scalpel or scissors (Fig. 2B). The small opening is enlarged to admit two fingers, which are used to protect viscera while the peritoneum is being opened throughout the length of the incision (Fig. 2C). When operating through a previous incision, one must be extra careful to avoid underlying adhesions involving bowel. If possible, the incision should begin 2 to 3 cm beyond the previous scar so that the peritoneum can be opened where it is relatively free of adhesions. Once the peritoneum has been opened, the fascia and peritoneum are held up with Kocher’s clamps so that the attachments of adhesions can be seen and carefully divided sharply to prevent thermal injury to the bowel.

When making the incision in the lower anterior abdominal wall, the surgeon must be careful to avoid a bladder injury. The bladder should always be decompressed by a Foley catheter. The anterior fascia can be incised to the pubic symphysis if needed, but the posterior incision involving the peritoneum should be angled away from the bladder. Blunt dissection in the space of Retzius can also be used to safely sweep the dome of the bladder away from the incision.

A paramedian incision is a vertical incision made 2.5 to 4.0 cm from the midline (Fig. 3A). It is deepened through the subcutaneous fat onto the anterior rectus sheath, which is opened for the whole length of the wound no more than 2 to 3 cm from the midline (Fig. 3B). The medial portion of the anterior rectus fascia is then dissected off the muscle to the medial edge of the muscle. This dissection is more difficult in the upper abdomen because of the tendinous attachments (inscriptions) of the rectus muscle to the anterior fascia. These are located just below the xiphoid, at the umbilicus, and occasionally midway between these two points. Segmental blood vessels are encountered when the tendinous inscriptions are freed and must be electrocoagulated or clamped and ligated. Once the muscle is free anteriorly and medially, it can be retracted laterally by a ribbon retractor because it is not adherent to the posterior fascia. The posterior sheath and the peritoneum are then incised vertically for the length of and in line with the skin incision. The lower rectus sheath differs from the upper in two respects: the posterior fascial layer is largely absent below the semicircular line of Douglas, and the deep inferior epigastric vessels need to be divided and ligated as they run across the lower part of the incision.

The paramedian incision avoids injury to nerves, limits trauma to the rectus muscle, allows an anatomical and secure closure, and permits good restoration of abdominal wall function. If necessary, it can be extended from the pubis to the xiphoid by slanting the upper end of the incision medially toward the xiphoid. When placed on the appropriate side, it can be used satisfactorily for any intra-abdominal surgery, although it is more time-consuming to make than a vertical midline incision. The theoretical advantage of this incision is that the rectus muscle resumes its original place and splints the incisions in the anterior and posterior sheath, and thus should diminish the risk of wound dehiscence and incisional hernia. However, despite the known hernia incidence with midline incisions, the paramedian incision is less commonly employed because it is more time-consuming.

The vertical muscle-splitting incision is performed in much the same way as the paramedian incision except that the rectus muscle is split longitudinally in its medial third, after which the posterior rectus sheath and peritoneum are opened in the same line. If the incision is short, it can be quickly made and repaired. It is very satisfactory when a limited incision is needed, for example, for placement of a Tenckhoff peritoneal dialysis catheter. An extensive incision should be avoided, however, because it results in more injury to nerves and muscle, and in substantially more bleeding than the midline or even the paramedian incision. If more than two nerves are sacrificed, the corresponding area of the abdominal wall may become dysfunctional postoperatively. The main value of this incision is in reopening the scar of a previous paramedian incision, when dissecting the rectus muscle from scar tissue in its sheath is very difficult and splitting the muscle may therefore be preferable.

Frequently, a right subcostal incision is used for open operations in the gallbladder, liver, and biliary system, particularly in obese or muscular individuals with wide costal angles (Figs. 1 and 6). A left-sided subcostal incision is used mainly for elective splenectomy. A bilateral subcostal incision provides excellent exposure in the upper abdomen. It is useful for performing total gastrectomy in an obese individual, for anterior exposure of both adrenal glands, for major liver resections, for pancreatic operations, and for hepatic transplantation.

The standard subcostal incision starts in the midline 2.5 to 5.0 cm below the xiphoid and extends laterally approximately 2.5 cm below the costal margin for a variable distance, depending on the patient and the exposure required (Fig. 6A). If the liver is enlarged, the incision may have to be placed at a lower level. The incision should not be made too close to the costal margin because, if a hernia develops, enough abdominal wall fascia must be available at the upper margin to permit a satisfactory repair or bony fixation would be required to the ribs. After the anterior rectus sheath is incised, the rectus muscle is divided along the course of the wound; electrocautery is used to control branches of the superior epigastric artery and other blood vessels, or suture ligatures can be used. The lateral abdominal muscles can be divided for a variable distance. Although the eighth intercostal nerve is almost invariably divided, care must be taken to preserve the ninth nerve to prevent weakening of the abdominal musculature. The incision is then deepened to open the peritoneum (Fig. 6B). Although the rectus muscle is divided, this results in no weakening of the abdominal muscles, provided that the anterior and posterior sheaths are repaired because the incision generally cuts only one intercostal nerve. The rectus muscles have a segmental nerve supply, allowing a transverse or slightly oblique division without significant risk to its innervation. Healing of the incision simply results in an iatrogenically produced additional fibrous inscription in the muscle.

Transverse incisions are ideally suited for open operations on the small intestine and are usually performed through an infraumbilical transverse incision, located approximately 2 to 3 cm below the umbilicus. For
operations involving the proximal small intestine, the incision can be favored to the left of the midline. Right-sided transverse incisions provide excellent exposure for the distal small intestine, cecum, and the ascending colon to the midtransverse colon. For right colon operations, the incision is placed 2 to 3 cm above the umbilicus. If the left transverse colon or splenic flexure is to be operated, the mirror-image incision on the left is satisfactory. In either incision, it may be extended to the opposite side of the midline as far as is necessary to obtain adequate exposure in either right or left colon procedures. As previously noted, a transverse incision may be suboptimal in an extended left hemicolectomy when the splenic flexure requires mobilization with a pelvic anastomosis.

The layers of the abdominal wall to be incised are, for all practical purposes, the same as those described for the subcostal incision. In patients who are thin, especially those with a narrow costal margin, the straight transverse incision is frequently modified with the lateral end being placed in the same plane as the umbilicus, and the incision can be somewhat oblique superiorly so that the midline end of the incision is several centimeters above the umbilicus. If the incision needs to be extended across the midline for some distance, it then becomes a bilateral subcostal incision. In the event that it is necessary to enter the superior portion of the abdomen, a vertical extension in the midline can be utilized as far superiorly as the paraxiphoid area. The xiphoid process can be excised if additional exposure is required. This extension gives excellent exposure to the upper quadrants as necessary for operations close to the hiatus or for hepatic resections, especially in larger patients.