Laparoscopic access systems have evolved greatly in the last decade. We have gone from reusable bladed trocars to disposable bladed and bladeless, from dilating trocars to bladeless optical-view trocars that let the surgeon visualize the trocar passing through the abdominal wall layer by layer. The goal of all these changes has been the same: achieving safe entry and creating the smallest possible defect in the abdominal wall fascia after removing the trocar.

Today's trocars require less force during insertion than before and cause less trauma to the fascia and other tissues. The less trauma that's used for insertion, the more likely the tissue will heal properly after the procedure. New innovations in trocar design have also greatly reduced the rate of injury during trocar insertion.

With the improvements in instruments and laparoscope design, we're able to use smaller diameter trocars for the majority of cases. Smaller incisions help reduce hernia rates and can result in less post-op pain. They can also save time, since a 5mm incision doesn't need a fascial closure. Another design improvement in trocars is a threading of the exterior to prevent slippage after initial placement.

All this evolution means that there's a lot of choice out there. Here are thumbnail sketches of many of the trocars used for general surgery.

Hasson and balloon trocars
Hasson trocars, the first modern trocars, named after Harrith Hasson, MD, are non-bladed trocars inserted using the open, or direct-cut, method. Direct cut is one of the most common and safest methods of laparoscopic access. The surgeon dissects the tissue layers to ensure safe entry into the abdomen. The trocar is then inserted under direct vision. Any case in which the trocar will be inserted at the umbilicus, such as laparoscopic cholecystectomy, Nissen fundoplication or splenectomy, would employ a Hasson trocar.

The Hasson trocar stays in place by way of sutures anchored in the abdominal wall fascia. These Hasson trocars are usually available only in 12mm versions. Reusable Hasson trocars were once common, but now most surgeons use disposable versions.

Balloon trocars can be used in place of Hasson trocars. The balloon trocar has a balloon that inflates at the end of the trocar with air from the room. The balloon anchors the trocar in the abdomen so that it doesn't need sutures in the fascia. Newer versions of balloon trocars are now latex-free for use in patients with latex allergies.

Optical access trocars
Until these trocars came along, the surgeon had to enter the abdomen "blind," without being able to see where the advancing tip of the obturator was going. As a result, the risk of complications used to be higher than today. Optical access trocars let you insert a laparoscopic camera in the trocar's hollow obturator. During insertion, the laparoscope lets the surgeon see the trocar going through the different layers of tissue as it moves its way into the abdomen. As the trocar dissects through the fascia and peritoneum, the surgeon can see it enter the abdominal cavity, helping to prevent organ injury.

Optical access trocars are good initial-entry trocars for procedures. Once the first trocar is in, the laparoscopic camera can be used inside the abdominal cavity to help with guidance for the insertion of other trocars.

Most optical access trocar systems are considered non-bladed trocars since they just have little plastic "wings" at the end of the obturator that help dissect and push the tissue out of the way.

Optical view trocars can be used before insufflation and can be used to insufflate the abdomen. All other trocars need a Veress needle for insufflation, except Hasson and balloon trocars, which are inserted through the direct-cut method and without insufflation.

Some systems have a special feature that lets you connect insufflation gas to the obturator. The gas then helps dissect the tissue as you go down through the layers.

Dilating trocars
Rather than slicing tissue, dilating trocars spread it apart. The advantage here is less damage to the tissue as the trocar goes through. The residual hole in the fascia is very small, and usually doesn't require closing. In most cases, these trocars require less force to insert because a needle surrounded by an expandable sheath is inserted first, creating a small hole. Then the needle is removed, leaving the sheath in the hole in the fascia. Inserting the trocar, which has a tapered end, into the sheath dilates the hole in the fascia created by the needle. The resistance of the dilated fascia against the sheath keeps the trocar in place so that the surgeon doesn't have to use sutures as anchors. Dilating trocars can be used as secondary trocars or, if a Veress needle is used to insufflate the abdomen beforehand, as initial trocars.

The advantage of the dilating trocar is that you don't have to close the larger 12mm ports, as you have to do for the cut-down method and other trocars of that size. Dilating trocars are suited for any case in which you need a stapler, endo catch bag, suturing device or any other device that only fits through a trocar 12mm or larger, including mesh for hernia repairs.

Bladed trocars
These use a sharp blade to cut through the tissue during insertion. Because they offer no visualization, they shouldn't be used as the initial trocar. Many surgeons have moved away from these trocars because the incidence of injury to the abdominal wall or abdominal organs can be high. However, bladed trocars still have a place in laparoscopic surgery. If you know you're going to close a fascial defect and need a trocar big enough for a certain instrument or to remove a specimen, the bladed trocar can be helpful in creating a hole in the fascia large enough for the instrument to pass through.

Non-bladed, non-optiview trocars
Like dilating trocars, these trocars push the tissue out of the way as the obturator advances. Pushing a blunt trocar through the tissue and fascia requires more force than using a dilating trocar. Although they're often called "bladeless," blunt trocars still cut some of the tissue. However, in general, blunt trocars are less traumatic than bladed trocars.

These inexpensive trocars are useful as secondary ports. Because they're not optical trocars, they usually cost less. After initial trocar placement, these can be used in almost any position and create very little in the way of fascial defects. They now come in 5mm, 10mm and 12mm sizes.

Single-use vs. reusable
Most trocars used in surgical facilities are disposable. However, many trocar systems are available in reposable (reusable) versions. Reposable trocars and obturators are usually made of a metal such as titanium that can be reprocessed. Some reposable systems have a disposable component that you need to replace each time. Maintaining the sharpness of the obturator tip in reposable trocars is a concern among some surgeons and facility managers. Reposable trocars also require special attention during reprocessing, as all cannulas do.

Innovations in trocars
One of the major frustrations of laparoscopic surgeons is the smudging of the laparoscope as it passes through the trocar valves. A few trocar systems designed to prevent smudging and fogging have hit the market. Two use an insufflator to create an air barrier, which eliminates the need for the trocar to have a valve to preserve intra-abdominal pressure. One drawback with these systems is that they're 12mm trocars, which means that the hole in the fascia should be closed when the trocar is removed.

Further development of smudgeless trocars would eliminate this time--consuming problem and would greatly ease the performance of surgeons in conducting laparoscopic procedures.

Minimally invasive surgery has come a long way but there are still a few challenges to overcome. We're getting there.