The Impact of Trocar-Cannula Design and Simulated Operative Manipulation on Incisional Characteristics: A Randomized Trial Malcolm G. Munro, MD, and Christopher M. Tarnay, MD OBJECTIVE: To evaluate the hypothesis that abdominal muscular and fascial defects associated with 12-mm blunt conical trocar-cannula system will be similar to those asso- ciated with 8-mm pyramidal trocar-cannula system, both with and without simulated operative movements. METHODS: A randomized trial was performed in an animal (white swine) model. Four trocar-cannula system groups were evaluated: group A, 12-mm blunt conical system, no operative manipulations; group B, 12-mm blunt conical system, standardized operative manipulation; group C, 8-mm pyramidal system, no operative manipulations; group D, 8-mm pyramidal system with standardized oper- ative manipulation. These 4 groups were randomly as- signed across 8 animals and 6 locations for a total of 48 insertions. After the cannulas were removed, the skin and subcutaneous tissues were dissected to expose the fascial wounds. Maximal incisional length, wound area, and mus- cle damage score were determined for each defect. RESULTS: Mean wound area was 8.58 mm 2 in group A, 9.71 mm 2 in group B, 9.83 mm 2 in group C, and 9.63 mm 2 in group D. Incisional length was 9.16 mm in group A, 9.61 mm in group B, 9.14 mm in group C, and 8.52 mm in group D. There were no statistically significant differences between any 2 groups. Mean muscle injury scores were also similar for all groups. CONCLUSIONS: Twelve-millimeter conical trocar-cannula systems create fascial defects similar to those of 8-mm pyramidal systems, both immediately after insertion and after simulated operative manipulations. Given the histor- ical low risk of wound dehiscence and hernia associated with pyramidal devices less than 10-mm in outside diam- eter, fascial closure of wounds created by conical systems may be unnecessary. (Obstet Gynecol 2004;103:681–5. © 2004 by The American College of Obstetricians and Gynecologists.) The use of laparoscopically guided gynecologic surgical techniques has allowed many complex procedures, pre- viously performed by laparotomy, to be accomplished in a minimally invasive fashion. The initial and critically important surgical step required for such procedures is the positioning of peritoneal access devices or trocar- cannula systems in the anterior abdominal wall. There are inherent risks associated with placement of laparo- scopic trocar-cannula system that include bleeding from the abdominal wall, injury to the great vessels of the pelvis, and damage to intraperitoneal viscera including the bowel and urinary tract. 1–4 More recently, wound dehiscence and hernia have been associated with laparo- scopic port insertion. 5 Although originally considered to be rare occurrences, these complications are more fre- quent than previously thought, occurring in 0.2–3.0% of cases. 6 The increasing risk of incisional dehiscence and hernia is likely related both to the larger diameter of the cannulas used in contemporary operative laparoscopy and to the increasing number of ports used in a given case. 5 Although reported with the use of 5-mm trocar- cannula systems, 7 dehiscence with such small-caliber devices is rare and is far more commonly reported in association with cannulas 10 mm or more in diameter. 6 Consequently, fascial closure has generally been recom- mended for incisions created with access systems with a 10-mm or greater internal diameter. Nevertheless, dehis- cence and hernia have been reported rather frequently despite attempted fascial incisional closure, an observa- tion that may reflect the paradoxical difficulty of consis- tently attaining adequate approximation of the wound 6 From the Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, California.. Presented at the Global Congress of Gynecologic Endoscopy, the Annual General Meeting of the American Association of Gynecologic Laparoscopists, November 17, 2001, San Francisco, CA. Financial Disclosure This work was performed under an unrestricted grant from ConMed Inc, Utica, NY. The grant support covered the cost of acquiring and maintaining the animals, laboratory staff, and our laboratory facility in addition to the services of our statistical consultant. There were no funds supporting the investigators’ sala- ries. Neither of the investigators has stock in the company nor do they have stock options. VOL. 103, NO. 4, APRIL 2004 681 © 2004 by The American College of Obstetricians and Gynecologists. 0029-7844/04/$30.00 Published by Lippincott Williams & Wilkins. doi:10.1097/01.AOG.0000120144.85187.61