Deciding the right type of surgical incision is extremely important.
The ideal incision allows:
- ease of access to the desired structures
- can be extended if needed
- ideally muscles should be split rather than cut
- heals quickly with minimal scarring
- aesthetically pleasing
It is also important that incisions are placed in the direction of lines of cleavage of the skin (Langer's lines) so that a hairline scar is the outcome. These lines correspond to the direction of collagen fibres in the dermis and epidermis.
Incisions should also be placed as far as possible from stoma sites in order to avoid interfering with the stoma site and causing complications such as retraction and prolapse of the stoma.
Surgical incisions on the abdomen can be divided into transverse, vertical and oblique incisions.
Vertical incision 1: Midline incision
Use: Virtually all abdominal procedures may be performed through this incision.
Location: in the midline of the abdomen, and can extend from the xiphoid process to just above the umbilicus. It can be continued to below the umbilicus by curving the incision around the umbilicus.
Layers of the abdominal wall: skin, fascia (camper's and scarpa's), linea alba, transversalis fascia, extraperitoneal fat and peritoneum.
- Adequate exposure of most if not all of the abdominal viscera
- Minimal blood loss as the incision is through the linea alba
- Minimal nerve injury
- Minimal muscle injury
- Can be quickly made, such as in an emergency and quickly closed with a mass closure technique
- Care needs to be taken just above the umbilicus where the falciform ligament is
- Midline scar
Vertical incision 2: Paramedian incision
Use: provides laterality to the midline incision, allowing lateral structures such as the kidney, adrenals and spleen to be accessed.
Location: about 2- 5cm to the left or right of the midline incision. Incision is over the medial aspect of the transverse convexity of the rectus.
Layers of the abdominal wall: skin, fascia (camper's and scarpa's) and the anterior rectus sheath are incised. The anterior rectus muscle is freed from the anterior sheath and retracted laterally. The posterior rectus sheath (if above the arcuate line) or transversalis fascia (if below the arcuate line), extraperitoneal fat and peritoneum are then excised allowing entry to the abdominal cavity.
- Provides access to lateral structures
- Rectus muscle is not divided
- Incisions in anterior and posterior sheath is seperated by muscle which acts as a buttress, therefore closure is more secure
- Can be extended by a curvilinear incision towards the xiphoid process if required
- Takes longer to make and close
- Incision needs to be closed in layers
- Difficult extension superiorly as limited by the costal margin
- Tends to strip the muscles of their lateral blood and nerve supply resulting in atrophy of the muscle medial to the incision
Vertical incision 3: Mayo-Robson incision
This is really a paramedian incision that has been curved towards the xiphoid process. It allows a bigger and wider opening. Dissection continues in the same fasical planes as the paramedian incision.
Transverse incision 1: Transverse incision
Use: right or left colon, duodenum, pancreas, subhepatic space.
Location: This incision is made just above the umbilicus, dividing one or both of the rectus muscles.
Layers of the abdomen: skin, fascia, anterior rectus sheath, rectus muscle (+/- internal oblique, depending on the length of the incision), transversus abdominus, transversalis fascia, extraperitoneal fat and peritoneum. The medial aspect of this incision will be through the layers just like as in the midline incision.
- Less pain than a midline incision
- Good access to midline upper GI structures
- Transverse incisions cause the least amount of damage
- As the recti have a segmental nerve supply, it can be cut transversely without weakening a denervated segment
- Muscular segments can be rejoined
- Commonly used in children and the obese as greater abdominal exposure is gained in comparison with the vertical midline. This is due to the longer transverse length of the abdomen in children and the obese.
- Limited lateral access in comparison with midline incisions that can then be extended
- More wound infections compared to midline thought to be due to greater difficulty in controlling bleeding and haematoma formation.
Transverse incision 2: Subcostal incision
Use: gallbladder and biliary tract, spleen. It is also known as the Kocher subcostal incision, after the person who discovered it. With the roof top or Chevron modification, access to oesophagus, stomach, kidney and adrenals and liver is also possible. Another modification is the Mercedes
Location: starts in the midline, 2-5 cm below the xiphoid, extending in parallel with the costal margin at about 2.5 cm below the costal margin. A rooftop of Chevron incision is a double Kocher incision. The mercedes incision involves a vertical incision from the rooftop incision, like a mercedes sign.
Layers of the abdominal wall: Skin, rectus sheath, rectus muscle, internal oblique, trasnversus abdominus, transversalis fascia, extraperitoneal fat and peritoneum.
- Greater lateral exposure
- Less painful to midline incision
- Less post-operative complications such as PE to a midline incision
- Heals well
- Longer operation time as the incision is closed in 2-3 layers
Transverse incision 3: McBurney's incision and the Lanz incision
Use: This is the incision of most appendicetomies and can be used in the left lower quadrant in left sided colonic pathology.
Location: McBurney's point, as described by Charles McBurney in 1884, is two thirds from the umbilicus and a third from the right anterior superior iliac spine. The incision is oblique beginning laterally from above and ending medially.
If palpation reveals a mass, perhaps an appendiceal abcess, then the incision is made directly over the mass.
Nowadays, the incision is made transverse and placed in a skin crease, the so called transverse Lanz incision as this is more aesthetically pleasing and the scar is hidden in the bikini line.
If it is anticipated that the incision will need to be extended, the oblique incision is used with lateral extension and as a muscle splitting (gridiron) surgical technique. Muscle splitting involves spitting the muscles fibres in a direction that is parallel to the direction of the muscle fibres.
Layers of the abdominal wall: skin, fascia, internal oblique medially and external oblique laterally, transversus abdominus, transversalis fascia, extraperitoneal fat and peritoneum.
- Aesthetically pleasing incisions as they both follow Langer's skin lines
- A wide range of pathologies in the right and left lower quadrants can be dealt with, with room for extension if required
- Minimal damage to muscles as muscle splitting techniques can be utilised
- Avoids damage to local nerves
- The ilioinguinal and iliohypogastric nerves cross the appendicectomy incision and there is a risk of injury. This can then predipose to inguinal hernia formation post-operatively. This is more evident with the Lanz incision.
Transverse incision 4: Pfannenstiel incision
Use: Allows exploration of the lower GI and UT, as well as the pelvic reproductive organs.
Location: A convex 12cm incision, located a the suprapubic skin crease about 5cm above the pubic symphysis. Once the peritoneum is reached, it is incised vertically, taking care to avoid the bladder.
Layers of the abdominal wall: skin, fascia, anterior rectus sheath, rectus muscle, transversalis fascia, extraperitoneal fat, perineum.
NOTE: this incision is below the arcuate line and this there is no posterior rectus sheath.
EXTRA: MAYLARD INCISION
This incision is placed a couple of cm's above the pfannenstiel and also provides good exposure of the pelvic organs. It cuts through the rectus fascia and muscle as well as external and internal obliques. Once transverse abdominus and transversalis fascia are reached, a muscle splitting technique is employed.
- A convex incision is made instead of a transverse as this parallels the course of the segmental nerves that are cut and so minimising muscle parasthesia and paralysis post-operatively. It also follows the cleavage lines in the skin resulting in less scarring
- Location of incision means it is hidden in the pubic hair line
- Limited exposure of the abdominal organs. Use of incision is therefore restricted to the pelvic organs
- High risk of injury to the bladder especially because the fascia thins towards the lower abdomen, leaving the bladder relatively exposed, and if the bladder is not catheterised during surgery
- Extension of the incision is difficult laterally
- Exploration of the deep pelvic organs is difficult making dissection in the obese difficult
Oblique incision: Thoraco-abdominal incisions
Thoracoabdominal incisions may be located in the RUQ or LUQ. They convert the pleural and peritoneal cavities into one. They allow good access to the lungs, liver and spleen. The left incision can also provide good exposure to the oesophagus and the stomach.
These incisions are small cuts in the skin made in the abdominal wall to allow the instruments of laparoscopy access to the contents of the abdominal cavity.
Their location will depend on the organ being operated on. Generally there will be 3-4. One is always at the umbilicus to allow a port for the camera. The other incisions will be located in one of the 4 quadrants for tools such as the griper, cutting and dissecting scissors and so on.
Care of the surgical incision
Surgical incisions may be closed with sutures, staples, steri-strips or local tissue glue.
It is important to keep the wound site clean and incisions are often covered with a protective dressing. Patients are encouraged to keep the wound as dry as possible to limit wound infection. Showering and bathing can resume after a couple of days. Wounds that are closed with nonabsorbable sutures and staples require removal of these materials first.
While gentle exercise is encouraged, it is important to avoid pressure, pulling and stretching on wounds.
As wounds heal, it is common for patients to see their wounds becoming itchy, red, swollen and wounds may even ooze sero-sangiunous fluid. These all represent the healing process. It is important to know what is normal so that abnormalities in wound healing that may represent infection, wound dehiscence, hypertrophic and keloid scars may be detected.