Access and trocar complications

The description of access and trocar complications covers all access techniques and the nature, prevention and treatment of injuries associated with minimally invasive peritoneal access. The technical key steps of the chapter are presented in a step by step way: trocars, hand-assisted laparoscopic surgery (HALS), fixation systems, direct vision, blind techniques, remaining trocars, injuries, closure, hernias.

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Access   and   trocar   complications

Authors
J Leroy, E Dutson, M Henri
Abstract
The description of access and trocar complications covers all access techniques and the nature, prevention and treatment of injuries associated with minimally invasive peritoneal access.
The technical key steps of the chapter are presented in a step by step way: trocars, hand-assisted laparoscopic surgery (HALS), fixation systems, direct vision, blind techniques, remaining trocars, injuries, closure, hernias.
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2005-03
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E-publication
WeBSurg.com, Mar 2005;5(03).
URL: http://www.websurg.com/doi-ot02en274.htm

Access   and   trocar   complications

1. Introduction
Laparoscopy has evolved greatly in the past 20 years. First developed by gynecologic surgeons, laparoscopy has been revolutionizing general surgery over the last decade. Apart from its known advantages, laparoscopy bears specific morbidities. Twenty percent to 40% of laparoscopic complications are caused by incidents that occur in the initial steps of a laparoscopic procedure and especially during positioning of the first trocar (Hashizume and Sugimachi, 1997). Although rare – 5 per 10,000 to 3 per 1,000 (Chandler et al., 2001; Champault et al., 1996) – these potentially preventable injuries have serious consequences, with a mortality rate of up to 13%.
We will review different access techniques and the nature, prevention and treatment of injuries associated with minimally invasive peritoneal access.
2. Trocars
• Definition
The word “trocar” is usually used to refer to the entire ensemble of the system. We can distinguish between the cannula, the actual trocar, which serves as a stylette through the cannula, the different valves for creating an air-seal, and the methods of fixation in the abdominal wall.
• Cannulas
Cannulas are in general made from plastic or metal. Plastic devices, whether they are transparent or opaque, need to be designed in such a way as to minimize the reflection of light from the laparoscope, though this problem is usually less severe when a tri-CCD camera is used. Unlike plastic cannulas, which have a high resistance and therefore act as electrical insulators, metal cannulas not only conduct electricity, but can actually have a capacitance effect if there is an escape current from an instrument. They thus need protection against electrical arcs.
The diameter of the cannulas (from 3 mm to 30 mm) has to be adapted for the type/size of instrument one wishes to use. There is always a difference in the marked exterior diameter of the cannula and the interior, or actual usable diameter. This difference varies from brand to brand. Some trocars have a cannula with a tapered tip to stabilize the instrument within the cannula. There are also cannulas of different lengths, which allow adaptation to the thickness of the parietal wall. Finally, the end of the cannula is either straight or oblique; an oblique tip is felt to facilitate the passage of the trocar through the abdominal wall.
• Trocar tips
• Cutting or bladed tips
The cutting tips of these trocars are either in the shape of a three-edged pyramid, or a flat two-edged blade. These tips are very effective at penetrating the abdominal wall by cutting the tissues as they pass through. Most of these bladed trocars have a spring-loaded internal recoiling system that withdraws the sharp tip immediately after it passes through the abdominal wall to reduce the likelihood of injuring any of the contents of the peritoneal cavity. The point either recoils into the cannula or into just the tip of the trocar.
• Conical tips
Conically tipped trocars are being used more and more because they are less traumatic to the tissues. The tip can be either pointed or blunt, and their primary advantage is that the parietal wall is opened by spreading the tissues layer by layer without actually cutting them. This seems to be associated with a decreased risk of hemorrhage and later herniation. Some trocars are hybrids incorporating a retractable flat blade with the conical tip.
• Blunt tips
Blunt-tipped trocars (e.g. “Hasson”) are also being used more and more. Tissue cannot be penetrated with these trocars. They can only spread tissue that has already been cut; hence they are used for the “open technique” of trocar placement.
• Optical tips
The optical-tipped trocars allow passage of the cannula through the abdominal wall under visual control. They use either an integrated retractable cutting blade or a transparent cutting cone. The laparoscope is placed into the cannula as it is passed through the abdominal wall in order to see each of the successive layers until the peritoneal cavity is entered.
• Ultrasonic tips
Ultrasonic dissecting tips are contraindicated for placement of the first trocar. Ultrasonic tips allow the passage of the cannula through the abdominal wall without excessive pressure, which should decrease the likelihood of injuring the intra-abdominal organs. They also provide coagulative hemostasis during the penetration of the abdominal wall, but the skin incision must always be of adequate size to avoid cutaneous burns. The reusable systems have to be sterilized after each procedure. Consequently more equipment is needed if multiple interventions are planned.
• Trocar cannulas
The original trocar (Endotip) provides a simultaneous transverse penetration by progressive division of the various layers of the abdominal wall, with visualization of the dissected planes and fixation of the cannula in the wall thanks to a system external screw threading.
3. HALS
• Generalities
• Definition
Hand-Assisted Laparoscopic Surgery (HALS) devices allow for the introduction of the surgeon's non-dominant hand into the peritoneal cavity without loss of the pneumoperitoneum. The use of hand-assisted techniques in difficult cases facilitates the surgical procedure and offers an interesting alternative to the purely laparoscopic approach (Southern Surgeons' Club Study Group, 1999; Targarona et al., 2002).
• Principles
Hand-assisted laparoscopic surgery allows for a reduction in the number of trocars compared to the purely laparoscopic approach (Meijer et al., 2000).
The proper placement of the hand-assist device is one of the fundamental principles of HALS. The hand-assist device should never be placed directly over the operative field. According to the principle of triangulation, the hand-assist device is ideally placed in the same position as that of the non-dominant operating trocar in the purely laparoscopic approach (Espalieu et al., 2000).
The introduction of the surgeon’s hand via the hand-assist device allows for tactile feedback and complements the information obtained visually.
Hand-assisted laparoscopic surgery greatly facilitates mobilization of the organs and helps for identification of the proper dissection plane (guided by the surgeon’s finger), thus minimizing oozing and blood loss.
HALS offers several real advantages during the procedure resulting in a significant time gain. This is especially true in obese patients as well as in cases of significant abdominal adhesions.
Several devices exist. First generation devices can be distinguished from second-generation devices (customized from 2000 onwards).
• 1st generation devices
• Pneumo Sleeve
The size of the incision for placement of the hand cannula is determined by the size of the surgeon's glove. A retractor-protector (Pilling Weck Corporation, Raleigh, North Carolina, USA), which is an open-ended plastic cylinder with a malleable ring at each end is then introduced into the abdominal cavity through this incision. This provides a seal for the skin wound both at the peritoneal and skin sites and keeps the incision open and also protects the wound against contamination by bacteria and malignant cells. The Pneumo Sleeve (Dexterity Surgical Inc.) is fitted under the hand cannula and manipulated to achieve the best possible angle for the surgeon’s arm during dissection. The adhesive backing is removed and the flanges are secured to the skin. A one-way valve located in the sleeve’s lumen prevents gas escaping from the abdomen. An additional cover is placed on the surgeon’s arm, which is impermeable to gas. The pneumo sleeve is entered and secured to the surgeon’s upper arm by means of a Velcro band to prevent gas escape. The hand is then placed through the hand cannula into the abdomen.
• IntroMit
The IntroMit (Medtech, Dublin, Ireland), is a single-piece device that requires an adhesive to be secured to the body wall. There is no sleeve is required, and the device can be placed without a pneumoperitoneum.
• HandPort system
In the HandPort system (Smith & Nephew, Andover, MA, USA), the surgeon must wear a sleeve that attaches to the inflatable base of the device. Insertion or removal of the hand from the abdomen requires removal of the sleeve from the device, causing an immediate loss of pneumoperitoneum.
• 2nd generation devices
• GelPort
The GelPort (Applied Medical) is a three-piece device that uses a woundprotecting sheath (inner ring), a wound retractor (outer ring), and a gel seal cap that affixes to the wound retractor. The seal that is created maintains pneumoperitoneum, even without the insertion of the surgeon's hand. Removal of the surgeon's hand from the abdominal cavity does not cause loss of pneumoperitoneum. Moreover, the gel seal cap can be pierced by a trocar or accessory instrument while maintaining a seal at the puncture site. The large surface area of this device requires an adequate area for application on the body wall and may not be ideal for lower-quadrant hand incisions in smaller patients. However, a unique benefit of this device is that it permits the insertion of instruments through the gel seal cap even while the hand is inserted in the abdomen.
• Omniport
The Omniport (a trademark of Advanced Surgical Concepts Ltd., and manufactured in Ireland; Tyco Healthcare Group) is an inflatable device through which the surgeon can rapidly remove and reinsert the hand without losing pneumoperitoneum. The device also can be insufflated to maintain pneumoperitoneum without hand insertion, allowing an accessory trocar and instrument to be inserted through this device.
• Lap Disc
The Lap Disc (Ethicon EndoSurgery Inc.) consists of inner and middle rings that are connected by a silicone membrane spanning the abdominal wall. A third outermost ring rotates on the middle ring and acts as an iris, which is tightened to seal the device around the surgeon's arm. There are no pieces that require assembly with this device and insertion is quick and simple. This device has the smallest diameter (12 cm) and can be placed on most abdominal walls without interfering with the placement of adjacent trocars.
4. Fixation systems
• Fixation systems
Once introduced into the abdominal wall, the trocar must be maintained in order to facilitate the procedure, avoid injury and decrease the risk of parietal wall contamination. There are multiple cannula fixation systems.They are directly fixed on the external surface of the trocar (grooves, screw threading, dilatable sheaths) or are separate from the cannula (screw threading on a separate cone, e.g. Hasson or balloon) These systems make it possible to keep the cannula in the parietal wall and ensure an external seal around it, though the ideal system does not exist. It is important that the trocar firstly stays in the parietal wall without causing cutaneous injury, and secondly that it can be moved within the wall during the procedure.
• Internal seal
• Valves
Valves provide internal air-seals, which allow instruments to move in and out within cannulas without the loss of pneumoperitoneum. They can be oblique, transverse, or in a piston configuration. These valves can be manually or automatically retractable during instrument passage. Piston valves provide excellent seals, but they are not as practical as some of the other systems. They require both hands during instrument insertion, which may explain why they are less often used in advanced laparoscopic cases. The flexible valves limit the carbon dioxide leaks during work whatever the diameter of the instrument used.
• Joints
Joints supplement the internal seal of the cannula and are located at the entry of the cannula, providing variable levels of resistance. These provide a complete air-seal during manipulation, and are made from either rubber or elastic. The resistance encountered during the insertion of the instrument or needle is what insures their efficacy.
• Ballooned trocars
• Fixation
These trocars are designed to provide fixation within the abdominal wall.
• Dissection
These trocars allow the creation of a working space, either preperitoneal or retroperitoneal. In certain trocars, the balloon can serve as a spacing system throughout the procedure.
5. Direct vision
• Generalities
Increasingly direct vision techniques are used and recommended by general surgeons for the introduction of the first trocar. Hasson’s technique (1971) is the safest technique for insertion of the first trocar (Bonjer et al., 1997). Relative indications for use include the following:
- multiple scars;
- thin patients;
- muscular patients;
- children.
The open technique presents 2 major advantages over the classical Veress needle technique:
- injuries to major abdominal vessels are less frequent (Catarci et al., 2001);
- visceral injuries, even if equal in incidence, can be recognized and repaired immediately (String et al., 2001).
However, 2 aortic injuries have been reported with the use of the Hasson trocar (Hanney et al., 1999). There is also no evidence to support an open technique in the absence of a hostile abdomen (body habitus or multiple scars), as systematic use of the open technique in the periumbilical area has not been shown to eliminate the risk of bowel injury in the absence of risk factors (Bhoyrul et al., 2001).
Non-recognized visceral injuries still occur with the open technique, as reported by Chandler et al. (2001).
• Techniques
• Hasson's
The technique involves direct open visualization of the tissues at every layer until the peritoneum is opened, followed by placement of anchoring sutures in the fascia to secure a conical collar. The trocar is then placed through the collar to establish pneumoperitoneum and access. Disadvantages include persistent uncontrolled carbon dioxide leakage in many cases, increased incision size and increased time for placement.
• Optical trocars
These permit smaller skin incisions and better visualization of tissues as they are penetrated, and have been shown in large series to be a safe and fast way to access the peritoneal space. Injuries can be recognized immediately, thereby reducing their potential morbidity. Disadvantages include the inability to remove the trocar during its initial advancement, which may change the original tract and confuse orientation, in addition to making it difficult to recognize the peritoneal layer (String et al., 2001). FDA reports also confirm deaths from major vascular injuries associated with the use of optical trocars (Bhoyrul et al., 2001).
• Mini-open technique
This technique, adopted by the authors, is described as follows:
- patient positioning is checked;
- thorough familiarity of the anatomy of the abdominal wall and cavity is used to evaluate positioning of vessels in relation to BMI (the aorta can be less than 25 mm away from the skin in very thin patients);
- complete muscle relaxation is achieved;
- peri-umbilical incision (most often supra-umbilical) is made with a number 11 blade without pushing the tip of the blade deeper than the skin;
- subcutaneous fat is dissected down to the fascia;
- the fascia is incised and grasped, and the peritoneum is grasped with a Kelly clamp and opened under direct vision;
- traction is maintained on the fascia while the blunt-tipped trocar is introduced under direct vision;
- the minimal incision on the fascia opens up with the perpendicular force exerted on it by the trocar. The use of this technique makes a purse-string suture unnecessary as it prevents air leaks;
- the scope is then introduced in the trocar.
• Videos
6. Blind techniques
• Generalities
These techniques are less recommended, because there have been a higher incidence of accidents reported. If delayed recognition of an injury occurs, morbidity increases. Even if there is no clear evidence to support the open technique in the absence of a hostile abdomen, it is still a recommended conservative approach.
• Palmer’s technique
• Skin incision
A small incision is made to allow the insertion of the Veress needle. Left sub-costal margin localization was advocated by Palmer in the 1940s because visceral-parietal adhesions are rarely encountered in this area. In addition, some authors feel that because the abdominal wall in the area is supported by the rigid thoracic wall, insertion of the needle is more controlled than in the peri-umbilical area. Others prefer umbilical access because in this location the abdominal wall is thin, even in obese patients. The Veress needle has a spring-loaded obturator, and a sharp-edged oval aperture that converts into a blunt tip when it passes the parietal peritoneum. Two distinct pops are felt as the surgeon, using constant pressure, passes it through the fascia and the peritoneum. The abdomen is then inflated with at least 3.5 L of carbon dioxide.
• Needle introduction
In order to introduce the needle safely and avoid inflating in the wrong anatomical planes, the following principles should be followed:
- use of a disposable needle, which makes a worn out spring-load mechanism and dull edge unlikely;
- incision of the skin prior to insertion of the needle to diminish resistance, preclude the use of excessive force and prevent potential injuries;
- use of an insufflation system that incorporates an electronically regulated feedback mechanism to avoid insufflation in a high-pressure area. These systems also prevent over-insufflation, regulate flow rate and even initiate desufflation if the pressure becomes too high.
• Trocar introduction
Technical errors in the insertion of trocars after creation of a pneumoperitoneum are the most common causes of injury, resulting from inadequate stabilization of the abdominal wall, excessive resistance to trocar insertion, and excessive, misdirected or uncontrolled force applied by the surgeon along the axis of the trocar (Bhoyrul et al., 2001; Chandler et al., 2001).
It is important to stabilize the abdominal wall by full insufflation, complete muscle relaxation, and use of counter-traction of the fascia or manual lateral or epigastric compression to increase the distance between the anterior abdominal wall and the retroperitoneal vessels and intra-abdominal organs.
It is important to ensure that the skin incision is of sufficient length and that the reusable trocar tip is sharp so that no resistance is offered, as this would force the surgeon to use excessive and uncontrolled force.
It is important to use balanced agonist force (muscles being used half-way between full contraction and extension, strong muscles used at sub-maximal level, trocar inserted slowly), associated with an antagonist force to stop further progress when resistance from the abdominal wall abruptly decreases after penetration of the trocar into the pneumoperitoneum. The table should be placed at a comfortable height and the surgeon should avoid reaching across the patient to place a lateral port.
It is important to introduce the umbilical trocar at an axis directed towards the pelvis to avoid the aorta/vena cava (i.e. below the bifurcations). Many surgeons recommend this. However, anatomical relationships vary with patient body habitus and the level of insufflation.
• Personal blind technique
This technique combines some of the safety of the open technique (Hasson) with the minimal abdominal wall trauma and limited skin incision associated with the Palmer technique. It also saves a non-negligible amount of time between insertion and closure. This technique is facilitated by the use of a new generation of disposable trocars with dilatable sheaths. It is not recommended, however, in patients with a previous periumbilical midline scar.
The following steps are used:
- periumbilical skin incision;
- location of fascial aponeurosis;
- traction on the aponeurosis;
- minimal incision of the fascia, which may or may not allow visualization of the peritoneum;
- introduction of the Veress needle with the dilatable sheath under a minimal perpendicular pressure while maintaining traction on the fascia;
- insufflation of the abdominal cavity to 12 mm Hg of carbon dioxide (around 3 liters for most patients);
- removal of the Veress needle while holding the dilatable sheath in place;
- after removal, the gas leak is controlled with the surgeon’s thumb;
- insertion of the canula with the dilating introductor into the sheath using a vertical push/pressure steadying the sheath with the other hand;
- removal of the dilating introductor and immediate surveillance with the laparoscope.
• Videos
7. Remaining trocars
• Generalities
The risk of injury persists during the introduction of subsequent trocars. Once the first trocar has been placed, a videoscopic panoramic exploration of the abdominal cavity should be undertaken to rule out complications. In the absence of adhesions, a clear view within the abdominal cavity allows placement of the remaining trocars under videoscopic guidance. Because some trocars penetrate the abdominal wall very easily, it is still necessary to maintain vigilance during their insertion and respect basic principles.
• Tricks
• Manual counter-pressure
One or two hands of the assistant (or the surgeon) maintain the distance between the parietal wall where the trocar is being inserted and the abdominal contents.
• Grasper counter-pressure
This cannot be performed until after the second trocar is inserted; a grasper is placed through the second trocar to provide counter-pressure from within against the abdominal wall as the third trocar is inserted. This is especially useful in areas where the peritoneum is pliable (supra-pubic area).
• Trocar counter-pressure
This is not possible unless the trocar used for counter pressure is of larger diameter than the trocar being inserted and the distance between the two does not exceed the length of the cannula of the trocar providing counter-pressure. This technique is often used in pediatric surgery.
It can be performed with the optical trocar: in this case, the laparoscope is pulled back within the trocar to avoid breaking the protective lens.
• Insertion control
Insertion control is performed with the finger of either the inserting hand or the opposite hand to avoid deep penetration of the trocar into the abdominal cavity. This should be performed with manual counter-pressure.
• Videos
8. Injuries
• Introduction
Penetration of the abdominal cavity requires:
- analysis of the abdominal wall;
- familiarity with the abdominal contents;
- heightened awareness;
- an unhurried approach.
Thorough familiarity with the anatomical relations of the abdominal wall and cavity is essential for the prevention of visceral and vascular injuries. No particular device nor entry technique have been shown to be safer (Chandler et al., 2001; Bhoyrul et al., 2001).
• Anatomy
• Iliac vessels
The cephalocaudal relationship between the aortic bifurcation and the umbilicus has been studied radiologically. The umbilicus is often located directly above or cephalad to the aortic bifurcation, and is consistently located cephalad to where the left common iliac vein crosses the midline. The aortic bifurcation is located more caudal to the umbilicus in the Trendelenburg position than in the supine position. The distance of the aorta from the umbilicus ranges from 0.1 cm in thin patients to 2.7 cm in obese patients (Nezhat et al., 1998; Hurd et al., 1992).
• Viscera
Trocar injuries to abdominal viscera occur if the viscera are unusually close to the point of trocar insertion. Distances between parietal peritoneum and underlying viscera can be increased to 6 to 7 cm by lifting the abdominal wall at the umbilicus with towel clips applied to the fascia of the umbilicus incision, and the distance is not reduced when force is applied at trocar insertion (Roy et al., 2001).
It should be noted that reports show 59% of patients with previous midline incisions and 28% of patients with previous suprapubic transverse incisions have anterior wall adhesions that may contain sections of the bowel (Levrant et al., 1997).
In addition, a full bladder or stomach may be injured if not emptied prior to Veress needle or trocar insertion.
• Injuries
• Visceral organs
The small bowel is the most commonly injured organ, followed by the large bowel and the liver (Schafer et al., 2001). Injuries to the small bowel and colon are significantly more likely to go unrecognized for more than 24 hours, and more than half of all bowel injuries do in fact go unrecognized (Chandler et al., 2001). This greatly increases mortality, up to 26% in some series (Bhoyrul et al., 2001; Chandler et al., 2001). Claims arising from entry access injuries, between 1980 and 1999, reported to the Physicians Insurers Association of America, and entry-injury medical device reports to the FDA, from 1995 through October 1997, were analyzed (Chandler et al., 2001). Five hundred and ninety four structures or organs were injured in 506 patients, resulting in 65 deaths (13%).
• Vascular injuries
Vascular injuries are less common. The epigastric vessels are most commonly injured, followed by the greater omentum and mesenteric vessels; least common are injuries to the retroperitoneal vessels (Schafer et al., 2001). Injury to a major visceral vessel (e.g. portal vein, hepatic artery, gastroduodenal artery) can carry a mortality rate of up to 44% (Chandler et al., 2001).
• Treatment
The key to minimizing morbidity following access injury is immediate recognition. Upon recognition, standard repair of visceral injuries should be carried out, and in many cases this can be accomplished laparoscopically. If visualization of the injury is inadequate, or if the surgeon is relatively inexperienced or uncomfortable with the situation, rapid conversion should be done.
In cases of vascular injury, conversion is the rule. It is imperative, however, to make an initial, rapid attempt to control the bleeding prior to conversion, as a large injury to the aorta or vena cava can become lethal in the time it takes to convert. Initial control of the bleeding can almost always be accomplished with placement of a sponge through the trocar and application of direct pressure to the injury. This often allows time to better assess the situation and identify the rare situation when a laparoscopic repair can be undertaken. In these cases, the basic principles of vascular surgery apply: obtain proximal and distal control and effect a repair or perform a ligation, depending on the vessel involved. However, the surgeon should be aware of the unique potential for carbon dioxide embolus due to pneumoperitoneum. This risk alone should discourage almost all attempts to manage a serious venous injury laparoscopically.
• Videos
9. Closure
• Generalities
The closure of the trocar holes is an important part of the procedure. A large number of parietal wall vascular injuries asymptomatic during the procedure (because of the trocar compression) can be dramatically revealed in the immediate postoperative period by a large internal hemorrhage or parietal wall hematoma, which can become huge.
For incisions larger than 8 mm, there is a risk of late development of incisional hernias; thus it is necessary to carefully close the fascial defects. Postoperative pain is often secondary to the technique of closure. Use of some types of trocars (e.g. Versastep) may possibly limit the risk of development of incisional hernia in larger trocars, because the end fascial defect is not as large as the trocar itself once the trocar has been removed.
• Technique
• Removal (rigid cannula)
With a conventional rigid cannula, an instrument is introduced and the trocar is withdrawn over it to check for bleeding under videoscopic control. If there is no bleeding, the trocar is re-inserted over the instrument, which is then removed.
• Removal (Versastep)
With a Versastep trocar, the rigid cannula is removed from the dilatable sheath, which is left in place in the parietal wall while the area is checked for bleeding. Again, if there is no bleeding, the sheath can either be removed or left in place until the remaining trocar sites have been checked in a similar fashion for bleeding.
• Exsufflation
The abdominal cavity should always be exsufflated prior to the removal of the last trocar in order to avoid incarceration of omentum or viscera into the incision sites. The last trocar should always be the camera trocar, and the laparoscope should be withdrawn into the cannula so that the layers of the abdominal wall can be inspected for bleeding as the trocar is withdrawn (Kadar et al., 1993). In the same fashion, it is also advisable not to leave too much irrigation in the abdominal cavity as it will be expressed with desufflation, which can push out intra-abdominal contents in the process (Howard and Sweeney, 1994).
• Suture closure
The closure has to involve all of the layers of the abdominal wall, including the peritoneum, to decrease the risk of herniation (Kadar et al., 1993). The deep layers, as a rule, are closed with a slow-absorbing suture, and the skin closure varies from author to author.
10. Hernias
Generalities
Trocar-site hernias are rare (Leibl et al., 1999). It has been calculated that the statistical incidence is between 0.8% and 1.2% and, apart from anecdotal descriptions, few publications describe trocar site hernias. This rate is therefore probably an underestimate, especially since a certain number of patients would be asymptomatic. The usual risk factors for development of abdominal wall hernias also apply to trocar-site hernias: respiratory insufficiency, obesity, malnutrition, ascites, wound infection and steroid use (Loriau et al., 2002).

Clinical presentation
The majority of trocar-site hernias are symptomatic within the first 15 days postoperatively. They can be, however, revealed later and likewise are asymptomatic in up to 25% of the cases from the series (Montz et al., 1994). The clinical presentation can be acute with occlusive symptoms or peritonitis, often related to small bowel incarceration. It can also present as simple local discomfort, which may or may not be associated with an abdominal wall mass. This can be especially difficult to detect in obese patients. It is in these cases that ultrasound or CT-scan can be of high utility to confirm the diagnosis (Maio and Ruchman, 1991).

Clinical aspects
Incision size:
The risk of hernia increases with the diameter of the trocar. Nearly non-existent for 5 mm and smaller trocars, the risk is even further reduced in obese patients (Reardon et al., 1999). For 10 mm holes, the risk has been reported to be 0.23% and 3.1% for 12 mm holes (Kadar et al., 1993). The size of the trocar is not the only cause, as the size of the fascial incision can be greater, or can expand with abdominal wall trauma during the case (Boike et al., 1995).
Trocar location:
The periumbilical region is a zone of weakness because it is the thinnest area of the abdominal wall. The risk of herniation here is furthered if there is already a pre-existing umbilical hernia. An extra-umbilical location decreases the risk of hernia but does not eliminate it, especially when trocars of 10 mm or larger diameter are used (Milkins and Wedgwood, 1994). From the series by Montz et al. (1994), 25% of the reported hernias were in an extra-umbilical location.
Type of hernia:
Direct hernias, which manifest as a lump are, as a rule, easy to diagnose. Oblique hernias, such as a Richter’s hernia, which develop far from the linea alba, represent a challenge diagnostically (Bourke, 1977). The contents of these hernias vary depending on the location of the trocar site. It can be a simple empty hernia sac, or it can contain the omentum, small bowel, less often colon, uterine tube or even bladder. Strangulation of the contents is not unheard of, especially in the immediate postoperative period.
11. Conclusion
Generalities
In both laparotomy and laparoscopy, the opening of the peritoneal cavity is a dangerous stage of the procedure. With the expected evolution of micro-instrumentation in laparoscopy, greater diligence will be required when it comes to initial access.
It should be remembered that even Hasson-type, open-incision, blunt cannulas are associated with potentially lethal small bowel injury, retroperitoneal vascular injury, death, abdominal-wall vessel laceration and other visceral injuries (Chandler et al., 2001).

Recommendations
Checklist
Minimization of complications is possible if the following points are kept in mind:
- complete a checklist prior to starting (much like a pilot);
- make sure of the presence of all members of the team (mentally as well as physically);
- verify all equipment;
- take your time;
- assure complete muscle relaxation and adequate skin incision;
- comply with equipment technical recommendations by the manufacturer;
- use a finger to control the depth of insertion of the trocar;
- use extra caution when unfamiliar with the materials being used;
- anticipate incidents before they occur (i.e. will there be a vascular surgeon available if needed?).

Dangers
The following points should be respected:
- do not neglect a pressure elevation at the beginning of insufflation;
- maintain the distance between the parietal wall and the abdominal contents with the introduction of subsequent trocars;
- carefully watch placement of bladed-tip trocars in zones of parietal wall vessels, introduction of bladed trocars in the direction of the retroperitoneal vessels or viscera;
- do not assume that equipment is completely safe-guarded;
- do not work with insufficient, worn out and/or unreliable equipment.
12. Reference