Saturday, February 7, 2009

Laparoscopic Entry Techniques

A wide variety of opinions exist regarding the best method for initial laparoscopic trocar entry. The three techniques commonly used are: open laparoscopy, which involves layer-by-layer dissection and then anchoring the trocar into the fascia; Veress needle insufflation, where the Veress needle is used to insufflate the peritoneal cavity prior to placing the trocar; and direct entry laparoscopy, where the trocar is inserted directly into the abdomen. The last technique can be done with an optical-entry trocar, which allows the surgeon to see the layers of tissue while pushing the trocar in. 

The issue over which technique is best centers around two main categories of injury: major vascular injury and bowel injury. Both of these injuries are rare but dozens of studies, both prospective and retrospective, have been done to give us solid numbers regarding the injury rate. 

Molloy et al. (Aust N Z J Obstet Gynaecol 2002: 42: 3: 246) have performed a meta-analysis of 51 studies performed before the year 2000. They found the following rates of injury per 1000 cases:
Veress Open Direct
Bowel injury 0.4 1.1 0.5
Vascular injury 0.4 0 0
Combined injury 0.8 1.1 0.5

These rates of injury are basically the same in the prospective studies as well. When patients were studied prospectively to Open vs the Direct entry techniques (eliminating the selection bias for patients at high risk for bowel injury), the following rates were found per 1000 patients: 

Open Direct
Bowel injury 0.82 0.31
Vascular injury 0 0
Combined injury 0.82 0.31

So Direct Entry wins again. 

Interestingly, virtually every vascular injury in the dozens of studies available occur with Veress needle entry. So both Open and Direct entry virtually eliminate the risk of major vascular injury. But the Open technique, first described by Hasson in 1971, poses a relative risk of 2.6x the rate of bowel injury vs the direct entry technique. 

Two additional things may tip the scales toward direct entry even more. First, more than half of the bowel injuries with direct entry occur in patients with previous vertical abdominal laparotomy incisions or previous multiple infra- or intra-umbilical incisions. Use of an alternative site, such as Palmer's point, 3 cm below the costal margin on the left side at the midclavicular line, would theoretically reduce the rate of bowel injury with direct entry by half. Secondly, use of optical trocars, allowing the surgeon to survey the layers of tissue during the entry, may afford a reduction in injuries as well. 

And there are other advantages of direct entry: smaller incisions (typically a 5mm port) which lead to less pain, less bleeding, and easier closure (usually just with Dermabond); quicker abdominal entry and shorter OR time; and no cases of gas embolism, which is a problem with Veress needle entry and which leads to 1 patient death in roughly every 5000 cases employing the Veress needle. 

So the clear winner seems to be direct entry laparoscopy, probably with an optical trocar. This contradicts years of traditional teaching and what purports to be common sense regarding avoiding major injuries at the time of initial port placement. Unfortunately, what the evidence holds out as the safest option is also the least used, with only about 10% of surgeons/gynecologists routinely using this technique.  

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