Avoiding Trocar Injuries Associated with Laparoscopic Surgery
Feb 2012 – by D. Soper, MD
Complications associated with laparoscopic surgery are rare, occurring in less than 1% of patients. Up to a half of all major intraoperative complications associated with laparoscopy, including the most devastating which is major vascular injury, occur at the time of surgical entry. Half of all bowel injuries occur during entry, with the small intestine at highest risk. Recommended methods for avoiding trocar injuries while gaining laparoscopic access during the insertion of the Veress needle and port trocars will be reviewed.
Surgeons must be familiar with the anatomy of the anterior abdominal wall as well as the structures in the lower abdomen and pelvis. The major arteries that lie in the retroperitoneal space of the lower abdomen and pelvis include the descending aorta, the common iliac arteries, and the internal and external iliac arteries. At the bifurcation, which occurs near the level of the umbilicus, the common iliac arteries diverge bilaterally. Near the pelvic brim, the internal iliac artery branches off dorsally and the external iliac artery continues caudally to enter the inguinal canal. The inferior epigastric arteries arise from the external iliac arteries and ascend upward through the transversalis fascia and then between the rectus abdominis and the posterior lamellar sheath. The deep inferior epigastric vessels run lateral to the umbilical ligaments and in most cases are seen intraperitoneally and identified easily. The analogous venous vessels lie dorsal to the arteries.
Insertion of the Veress needle and primary trocar for initial entry remains the most hazardous part of laparoscopy accounting for 40% of all laparoscopic complications and the majority of fatalities. Patients should NOT be in Trendelenburg position during initial trocar insertion.
The primary site of entry into the abdomen is located in the midsagittal plane at the lower margin or base of the umbilicus. This location was originally chosen for cosmetic and safety reasons. This safety depends, however, upon the direction and angle of insertion.
The umbilicus is an excellent anatomic landmark to determine the midline. However, instruments need to be placed in a direction parallel to the long axis of the patient so that the sharp tip remains in the midline. A deviation as little as 20 mm from parallel places an instrument tip almost 4 cm from the midline.
In non-obese women, the Veress needle or trocar should be inserted at 45 degrees from the horizontal plane of a patientís spine. At this angle, the abdominal wall thickness varies from 2 to 3 cm and distance to the major vessels averages 6 to 10 cm. To minimize abdominal wall thickness in obese patients, it is recommended that the needle or trocar be placed close to 90 degrees from the horizontal plane of the patientís spine. At this angle in the obese patient, the distance to these vessels averages 13 cm.
Many surgeons prefer to insert the primary trocar following insufflation of the abdomen to 25 to 30 mm Hg. This makes the anterior abdominal wall stiffer preventing the umbilicus from being depressed toward the major vessels.
The Veress needle should be open when inserted. The surgeon can feel or listen for two clicks (the double click test) as the needle is placed through the anterior abdominal wall (click #1 = anterior rectus sheath, click #2 = through the peritoneum). The needle can be felt to be freely movable at a fulcrum located within the anterior abdominal wall (waggle test). A drop of saline can be placed in the open needle hub and the abdominal wall lifted (hanging drop test). If the drop is drawn into the needle, it suggests that the tip is within the abdominal cavity.
Open laparoscopy avoids blind placement by incising the periumbilical fascia and peritoneum and advancing a blunt trocar directly into the peritoneal cavity.
Direct trocar insertion is another method of entry. The primary trocar is placed without prior insufflation. Although this technique avoids the risks associated with Veress needle placement, it may increase the risk (0.04% to 0.06-0.09%) of major vessel injury.
Alternatively, left upper quadrant insertion can be used. This technique is recommended by some surgeons to decrease the risk of bowel injury in patients with prior abdominal surgeries. The left upper quadrant insertion (Palmerís Point) is located 3 cm below the middle of the left costal margin and the Veress needle is inserted perpendicular to the patientís skin.
The safety may well be enhanced using direct visualization. This technique utilizes a small diameter laparoscope that is placed in the left upper quadrant of the abdomen (Palmerís Point). The trocars are then placed under direct visualization. This is especially helpful in patients who have had prior abdominal surgery.
Many techniques can be used for insertion of secondary ports. Transillumination helps to identify the superficial vessels but they are difficult to see in the obese patient. The umbilical ligaments can be identified and the inferior epigastric arteries arising from the inguinal ring may be visualized. When laparoscopic landmarks are not visible to guide placement, secondary trocars should be placed 5 cm superior to the midpubic syphysis and 8 cm lateral to the midline in an effort to avoid injury to the vessels of the anterior abdominal wall, predominantly the epigastric vessels. However, this location is often directly over the external iliac vessels. Therefore care should be taken to control the direction, depth and speed during secondary trocar insertion. The direction of insertion is determined by abdominal wall anatomy and proximity of the underlying structures. The trocar should be placed as close to possible to perpendicular to the abdominal wall and peritoneum. A more oblique insertion can make entry into the peritoneal cavity more difficult as the length from insertion site to peritoneal cavity increases and an oblique insertion can injure the abdominal wall vessels even when the initial skin placement is well lateral. The depth of secondary trocars should be limited. Once the trocar sleeve is through the peritoneum, the sheath can be further advanced under direct observation preventing injury to the underlying structures. The speed of insertion should be slow. Prior to incision of the skin and trocar insertion, injection of 0.25% Marcaine with epinephrine 1:100,000 using a 1.5 inch long needle along the projected trocar insertion site is very helpful. This not only allows one to visualize where the needle enters the peritoneal cavity but it also provides perioperative anesthesia for the trocar site.
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