DO DISPOSABLE TROCARS AND PNEUMOPERITONEUM

PREVENT BOWEL INJURY AT LAPAROSCOPY?

by A. Alhage, M.D.

D. Lanvin, M.D.

D. Querleu, M.D.

The reported incidene of bowel injury during gynecologic laparoscopy reanges from 0.1 to 0.3% for diagnostic laparoscopy and 0.38 to 0.52% for laparoscopic surgery (1-2). Bowel complications due to Veress needle or umbilical trocar insertion are reported to occur in 0.1 to 0.4% of laparoscopic procedures.

Some laparoscopists favour the direct insertion technique without previous pneumoperitoneum for initial trocar placement. Overall, the direct insertion technique reduces the number of blind insertions of instruments into the peritoneal cavity from two to one.

The purpose of our study was to study was to compare the incidence of bowel injury after Veress needle insufflation (VNI) versus direct troca insertion (DTI) and after insertion of a disposable (DT) (Endopath*, Ethicon Endosurgery Inc., Cincinnati, Ohio) versus a reusable trocar (RT) in rabbits which either has not or has previously undergone abdominal surgery.

Eighty adult, female virgin New Zealand white rabbits, weithing 2400 to 4000 g, were used in this study. For each protocol, the randomization was made ont he choice of the animal and the treatment to be given. We have formed five balanced factorial plans of eight rabbits for each protocol. In protocol 1, the rabbits had no preliminary surgery. They were randomly assigned to one to two groups, then in one of the sub-groups as follows: Group A (n=20), previous Veress needle insufflation, Sub-group A1 (n=10): use of a disposable trocar, Sub-group A2 (n=10): use of a reusable trocar. Group B (n=20) direct trocar insertion, Sub-group B1 (n=10): use a disposable trocar, Sub-group B2 (n=10): use of reusable trocar.

In the protocol 2, the animal underwent a first operation to induce abdominal sidewall adhesions. Three weeks after initial surgery, four groups were constituted according to the same study design as described in protocol 1: Group C (n=20): Veress needle insufflation, Sub-group C1 (n=10): use of a reusable trocar; Group D (n=20) direct trocar insertion, Sub-group D1 (n=10): use of a disposable trocar, Sub-group D2 (n=10): use of a reusable trocar.

A midline laparotomy was performed immediately after the trocar insertions. The number of bowel injuries was assessed. The data are expressed as total number of injuries according the treatment (protocol 1 or 2, and VNI or DTI, and DT or RT). Comparison of average perforation rates between groups was performed using analysis or variance. A p value <0.5 was accepted as statistically significant.

Fifteen bowel injuries occurred in protocol 1. In Group A, four injuries were noted. Two of them were due to the Veress needle and two were due to a reusable trocar. In Group B, eleven injuries were noted: three of them were due to a disposable trocar and eighte were due to a reusable trocar.

In protocol 2, two rabbits showed no adhesion; thirty-eight rabbits (95%) had abdominal sidewall adhesions. Sixty-three bowel injuries occurred. In Group C, twenty-four injuries were counted, seven of them were due to the Veress needle, nine were due to reusable trocar and eight were due to a disposable trocar. In Group D, thirty-nine injuries were counted: seventeen of them were due to a dispoable trocar and twenty-two were due to reusable trocar.

No significant interaction was found between three factors (prior abdominal surgery, Veress needle insufflation, type of trocar). There is no statistical difference in protocol 1 between direct trocar insertion and Veress needle insufflation (p=0.54). The use of disposable trocars significantly reduces the number of perforations. In protocol 2, Veress needle insuflation significantly reduces the number of bowel injuries. There was no statistical difference between the two types of trocars (p=5).

The purpose of this study was to compare the bowel complication rate of Veress needle insufflation versus direct trocar insertion and of disposable trocars versus a reusable trocar. Our goal was achieved using a rabbit model. In protocol 2, 955 of the female rabbits presented with surgically-induced abdominal sidewall adhesions. Prior abdominal surgery significantly affect the risk of bowel injuries with both Veress needle insufflation and direct trocar insertion.

Three prospective clinical randomized studies have evaluated Veress needle insufflation versus direct trocar insertion. No complication was observed in two studies. In another study, a perforation of the colon requiring conversion to laparotomy was secondary to direct trocar insertion technique. Additionally, minor complications with Veress needle insufflation occured. The sample size in the three studies was respectively 252,200, and 212 patients, too small to reach statistical significance given the low incidence of bowel injury in clinical setting.

Disposable trocars prevent a significant number of bowel injuries in animals without previous abdominal surgery. In the presence of abdominal wall adhesions, no significant difference between disposable and reusable trocars was found. Thus, disposable trocars do not improve the safety of laparoscopic access in case of prior abdominal surgery or abdominal sidewall adhesions. This can be explained by the insertion. When bowel loops are stuck to the abdominal wall, they may be injured whatever the type of trocar. In absence of this risk factor, disposable trocars improve the safety.

The results of our study confirm that prior abdominal surgery and abdominal side wall adhesions increase the risk of trocar injury. Specific precautions are mandatory in such cases. The use of a safety test with a syringe filled with saline (making no bubbles when there are adhesions on the insertion site of the initial trocar) could improve the safety of the procedure. Most laparoscopists suggest open laparoscopy for patients at risk of bowel adhesions. This point is currently the subject of another experimental study in our laboratory.