Original Article

Laparoscopic Peritoneal Entry with the Reusable ThreadedVisual Cannula

Artin M. Ternamian, MD*, George A. Vilos, MD, Angelos G. Vilos, MD, Basim Abu-Rafea, MD,Jessica Tyrwhitt, BSc, and Natalie T. MacLeod, BScFrom the Department of Obstetrics and Gynecology, Division of Gynecologic Endoscopy, St. Joseph’s Health Centre, University of Toronto, Toronto Ontario,

Canada (Drs. Ternamian, Tyrwhitt, and MacLeod); Department of Obstetrics and Gynecology, St. Joseph’s Health Centre, University of Western Ontario,

London Ontario, Canada (Drs. George A. Vilos and Angelos G. Vilos), Ontario, Canada, and Department of Obstetrics and Gynecology, King SaudUniversity (Dr. Abu-Rafea), Riyadh, Saudi Arabia.

ABSTRACT Study Objective: To estimate the feasibility, reproducibility, and safety of laparoscopic port establishment using a trocarless

The authors have

products or comp

Presented in part

ogy, Las Vegas,

Kurt Semm awar

Dr. Ternamian inv

tant for Karl Stor

product described

Corresponding au

partment of Obste

Rd, Toronto, ON

E-mail: artin.tern

Submitted Septem

Available at www

1553-4650/$ - see

doi:10.1016/j.jmi

and externally threaded visual cannula (TVC).

Design: Multicentre, prospective, observational study (Canadian Task Force classification II-2).

Setting: Three university-affiliated teaching hospitals.

Patients: Four thousand seven hundred twenty-four women (median age, 34 years; median body mass index, 25) underwent

laparoscopic surgery.

Intervention: After administration of general anesthesia, the Veress needle was inserted at the umbilicus or the left upper quadrant

(LUQ) using Veress intraperitoneal pressure of 10 mm Hg or less as proxy for correct placement. Transient high intraperitoneal

pressure of 20 to 30 mm Hg was attained, and primary and ancillary ports were established using the reusable trocarless TVC.

Measurements and Main Results: Institutional research ethics board approval and patient consent for video capture were

obtained. Primary umbilical entry was established in 4598 patients (97.33%), primary LUQ entry in 123 (2.60%), and primary

suprapubic entry in 3 (0.06%) patients. Peritoneal preinsufflation was abandoned when 3 consecutive umbilical or LUQ Veress

needle insertion attempts failed. Some patients at high risk with known peritoneal adhesions or previous lower abdominal mid-

line scars did not undergo preinsufflation, and the trocarless TVC was applied directly. Surgery was postponed in 3 patients in

whom insufflation failed, to enable further counseling and appropriate consenting. There were no serious abdominal wall or

intraabdominal vascular injuries. One transverse colon, densely adhered to the umbilical region, was injured, which was rec-

ognized and repaired intraoperatively. Residents, fellows, or faculty recorded entry-related data on forms postoperatively for

study and analysis.

Conclusions: Establishing peritoneal ports with the trocarless TVC is feasible, reproducible, and seems to be highly adoptable.

Journal of Minimally Invasive Gynecology (2010) 17, 461–467 � 2010 AAGL. All rights reserved.

Keywords: Laparoscopic entry; Laparoscopy; Threaded visual cannula; Trocarless entry; Veress needle pneumoperitoneum; Visual peritoneal entry

no commercial, proprietary, or financial interest in the

anies described in this article.

at the 37 Global Congress of Minimally Invasive Gynecol-

Nevada, October 28–November 1, 2008, and received the

d for excellence in pelviscopy.

ented the trocarless Threaded Visual Cannula, is a consul-

z Endoscopy, and holds some proprietary interest in the

in this article.

thor: Artin M. Ternamian, MD, Associate Professor, De-

trics and Gynecology, University of Toronto, 77 Truman

, M2L 2L7 Canada.

amian@utoronto.ca

ber 2, 2009. Accepted for publication March 6, 2010.

.sciencedirect.com and www.jmig.org

front matter � 2010 AAGL. All rights reserved.

g.2010.03.001

The ability to access body compartments to diagnose, un-

derstand, and treat diseases is a fundamental tenet of contem-

porary medicine. Endoscopy requires an entry point through

which optical and other instruments are introduced to access

the internal environment. Entry may be via a natural perma-

nent orifice (bronchoscopy, colonoscopy, or hysteroscopy),

an artificial temporary port (thoracoscopy, laparoscopy, or

culdoscopy), or contemporary hybrid conduit (natural orifice

transluminal endoscopic surgery, transanal endoscopic sur-

gery, or transvaginal endoscopy).

To create artificial temporary ports (e.g., for starting an in-

travenous line, administering spinal anesthesia, performing

liver biopsy, inserting a central line, or placing a laparoscopic

462 Journal of Minimally Invasive Gynecology, Vol 17, No 4, July/August 2010

port), instruments are engineered with an identical mechani-

cal model that has changed little over the years, and include

a trocar and a cannula. The operator holds the access device

with the dominant hand and applies considerable linear force

to a central spike, sheathed into an outer cannula, toward the

body area of interest. The central spike is pointed and sharp to

minimize penetration force, and has no mechanism to deter-

mine correct placement or to deter overshoot. The 2 most crit-

ical aspects of inadvertent laparoscopic trocar complications

(overshoot of a sharp trocar and failure to recognize, in real

time, visceral injury) are overlooked. When the operator be-

lieves to have attained the correct required depth (propriocep-

tive tactile haptics), penetration force is desisted, the central

spike is retrieved, and the intended task is performed.

The literature is replete with publications from reputable

centers that have identified several laparoscopic entry perfor-

mance shaping factors that when collated contribute to inad-

vertent entry injury irrespective of surgeon skill and training

[1]. Conventional trocar and cannula entry entails inherently

error-prone factors that render port creation intuitively haz-

ardous. Application of uncontrolled, linear and excessive

penetration force to a sharp and blind trajectory, with no

mechanism to restrain overshoot and no means to archive, re-

call, or analyze error, epitomizes instrument and method en-

gineering design oversight that disregards contemporary

fundamentals of human factors and patient safety. Capturing

force, instrument, and tissue interface conveys a wealth of

important port-related data that enable researchers to better

understand accident causation, analyze surgical error, and

improve patient safety.

Introduction of the trocarless threaded visual cannula

(TVC) method and instrument is not intended to eliminate

all inadvertent entry errors; rather, it encourages surgeons to

archive port creation, heed important port safety cues, and

learn from port placement mishaps. Moreover, it is a risk man-

agement and patient safety initiative to raise operating team

entry error awareness and improve surgical error recording

and reporting compliance. ‘‘Error does not become a mistake

until we refuse to correct it’’ (President John F. Kennedy) [2].

Real-time visual primary entry enables error archiving and

replay capability for early mishap detection and correction be-

fore irreparable patient harm is sustained. Irrespective, all

visual entry systems require knowledge of anatomy, identifi-

cation of navigational cues, and recognition of monitor im-

ages (situational and perceptual awareness) for safe

deployment. Given the infrequency of serious laparoscopic

entry injuries, our total number of applications are modest,

and we lack a real control group. However, injuries associated

with closed entry during the previous 14 years served as proxy

for historical control. In effect, to demonstrate a bowel injury

rate-difference of 50% requires a study population of about

800 000 patients. Consequently, most laparoscopic entry pub-

lications that compare different systems will always be under-

powered [3]. An alternate scientifically tested method needs

to be explored and adopted to better understand entry methods

and prevent primary port injury. High-reliability organiza-

tions (e.g., nuclear, space, and mining industries) are required

to operate in zero fault tolerance environments in which the

incidence of adverse events is extremely rare. To achieve

this seemingly impossible operational objective, it is accepted

practice to deconstruct error prone tasks (trocar insertion),

identify important performance shaping factors, and re-

engineer critical steps to infer added safety. Introduction of re-

dundancies and elimination of the identified accident prone

factors renders task performance less dangerous and recurrent

incidents theoretically less likely by virtue of the new design.

When published port-related factors are eliminated and

patient safety redundancies are introduced, entry becomes

less hazardous. This enables real-time recognition of injury

(heightened situational awareness), offers mishap archiving

capabilities for analysis of accident causation (eliminates

hindsight bias), and develops error aversion skills (warning

annunciation) that conventional trocar and cannula entry

methods and instruments fail to offer.

To our knowledge, the trocarless TVC method and instru-

ment are the first to enable body cavity access (animal and

human) by applying a blunt cannula where a pointed or sharp

central trocar is not required, linear penetration force is con-

siderably less and is replaced with radial torque, tissue layers

are tented away rather than dented toward the abdomen, the

cannula houses the laparoscope without an intervening

pointed crystal that distorts visual layer enunciation, and

overshoot is traded for exquisite entry control.

Laparoscopy is less disabling and safer than laparotomy

(overall risk, 8% vs 15%) [4], and major complications

with serious consequences occur in only 1 in 1000 proce-

dures. Studies have demonstrated that more than 50% of

bowel (0.4/1000) and major vessel (0.2/1000) injuries occur

during primary entry [5,6], when 80% are attributed to trocars

[7]. Trocars are the most common laparoscopic devices that

cause injuries, two-thirds of which are recognized postoper-

atively (http://www.piaa.us/Laparoscopic Injury Study).

Endoscopists have adopted several methods and instru-

ments to prevent mishaps [8,9]; however, no one entry

system has demonstrated safety over another [3,8,9].

Despite the evidence, some surgeons assume that the open

method is safer, advocate its exclusive use, and purport

failure to do so in all circumstances to imply negligence

[8]. Gynecologists worldwide practice closed entry

[3,8–10] where safe application requires correct Veress

needle and trocar placement. The most reliable correct

Veress needle placement indicator is the initial Veress

intraperitoneal pressure reading of less than 10 mm Hg

[11–13]. In addition, primary port insertion is less

hazardous when transient high intraperitoneal pressure of

25 to 30 mm Hg is induced, penetration force is reduced,

and vision is introduced. The trocarless TVC minimizes

controls and realigns penetration force from linear to radial

[14–17].

Herein, we review 3 centers’ experience in which the tro-

carless TVC cannula was used exclusively for primary and

ancillary ports. The importance of decreasing and realigning

Ternamian et al. Trocarless Visual Laparoscopic Entry System 463

penetration force, averting overshoot, controlling insertion,

and offering visual entry has been described elsewhere

[1,4,6,15,17].

Fig. 1. Endo-TIP trocarless threaded visual cannula with 10-mm, 0-degree

laparoscope.

Material and Methods

From 1984 to 1997, both principal authors (A.M.T. and G.A.U.)

practiced closed primary peritoneal entry, and injuries associated

with this technique were published by Vilos et al [18] and serve

as a historical control group. Subsequently, primary entry with the

trocarless TVC was adopted [19]. In the present study, sophisticated

statistical analysis was not conducted on the collated data; however,

for further study, a database (Microsoft Office Access; Microsoft

Corp., Redmond, Washington) was developed to include all patients

undergoing laparoscopic surgeries.

After administration of general anesthesia, the Veress needle is

connected to the insufflator with flow rate set at 10 to 30 L/min,

and pressure at 20 to 30 mm Hg. Because flow-through depends

on the fourth power of a tube’s radius (Poiseuille’s law), delivery

of carbon dioxide is limited by the Veress needle inside diameter

and never exceeds 3 L/min irrespective of insufflator pressure and

flow-rate setting. When insufflation is complete, the needle is re-

trieved, and a defogged 0-degree laparoscope is held in the nondom-

inant hand and sheathed into the trocarless TVC (EndoTIP; Karl

Storz Endoscopy, Tuttlingen, Germany) so that the distal end of

the telescope is 1 cm short of the end of the cannula (Fig. 1). The

cannula, held perpendicular to the supine abdomen with the domi-

nant hand, is lowered into the umbilical well to rest on the exposed

rectus fascia, then rotated clockwise using minimal downward force.

The cannula blunt tip parts the abdominal layers in sequence and

lifts them along the cannula outer threads as it enters the peritoneum,

with no overshoot and exquisite control (Fig. 2). The insufflator is

then reset at 15 mm Hg or less before the operation is started.

When the operation ends, the ancillary ports are removed under vi-

sual control, and the peritoneum is gradually desufflated. The TVC,

held in the dominant hand, is rotated counterclockwise, and receding

abdominal layers are observed through the sheathed laparoscope

(Fig. 3).

Results

Over 10 years, 4724 women (median [range] age, 34 [10–

87] years; body mass index, 25 [15–58]) underwent emergent

or elective laparoscopy. Primary entry was umbilical in 4598

patients (97.33%), and through the left upper quadrant (LUQ)

in 123 (2.60%). In 3 patients (0.06%), the Veress needle and

primary cannula were inserted midline between the symphy-

sis pubis and umbilicus.

Primary and ancillary port placement with the trocarless

TVC was successful in all patients (Dr. Ternamian). Of

patients that required conversions to laparotomy after suc-

cessful entry, none was attributed to access failure or cannula

complications. These patients sustained no port-related

bowel or vessel injuries and no long-term health conse-

quences. Though some minor insufflation complications

were encountered, none were cannula related, and no laparos-

copy was aborted because of their occurrence.

In most patients (93%; Dr. Ternamian), primary port (um-

bilical or LUQ) entry was successfully established with the

trocarless TVC after Veress needle insufflation. Direct nonin-

sufflated entry with the TVC was used in a few patients who

were identified preoperatively as high risk or in whom 3 con-

secutive (umbilical or LUQ) insufflation attempts failed; in

these patients, noninsufflated entry with the trocarless TVC

was used. Patients at high risk were assigned to either nonin-

sufflated umbilical primary peritoneal entry (n 5 42; 5.5%)

or underwent preinsufflation through the LUQ ,with TVC ap-

plied through that same site (n 5 37; 4.9%). In only a few pa-

tients was direct noninsufflated LUQ primary TVC used.

None of these patients sustained any serious complications.

Of our patients, 27.37% had undergone at least 1 previous

laparoscopy (maximum, 5 previous laparoscopies), and

25.66% had undergone 1 or more previous laparotomies. A

considerable number of these patients had undergone com-

bined procedures.

In 3 patients (0.06%; Dr. George Vilos), insufflation was

abandoned because of persistently high pressure after 3 failed

umbilical and LUQ attempts. Two patients underwent lapa-

roscopy later, with successful umbilical entry; the third failed

to return. There were no serious intra-abdominal vascular in-

juries. In 1 patient, the transverse colon was firmly adherent

to the umbilical region and was injured during primary can-

nula insertion. The injury was immediately recognized and

repaired, with uneventful recovery. Sudden inadvertent de-

sufflation and loss of visual cues preceded this event, and ab-

dominal layers were not readily discernible.

Few port sites required fascial closure because abdominal

layers are not transected during trocarless entry and the

stretched port tract recoils during TVC removal (Fig. 3).

No abdominal-wall vessel injuries occurred because those

crossing the TVC path are displaced radially rather than

transected by a sharp trocar [15,16]. No primary cannula

extrusions occurred, and few ancillary TVCs were displaced.

Discussion

Several aspects of peritoneal entry remain to be under-

stood because port creation entails error-prone PSFs that

Fig. 2. Primary umbilical port entry sequencing with the Endo-TIP trocarless threaded visual cannula after insufflation to 25 mm Hg. A, Cannula resting per-

pendicular to anterior rectus fascia with 0-degree laparoscope sheathed 1 cm short of end of cannula. B, Clockwise rotation parts anterior rectus fascia to expose

rectus muscle fibers (asterisk). C, Further rotation reveals and parts posterior rectus fascia to expose preperitoneal fatty layer. d, Peritoneal membrane transillu-

minates and appears grayish blue when no port site adhesions are present (error annunciation). E, Cannula rotation splits taut peritoneal membrane to expose

peritoneum. F, Rotation advances cannula under exquisite control and vision with no overshoot.

464 Journal of Minimally Invasive Gynecology, Vol 17, No 4, July/August 2010

remain hazardous irrespective of surgical proficiency. Use of

uncontrolled, linear, and excessive penetration force, to

a sharp and blind trajectory, with no mechanism to restrain

overshoot and no means to archive, recall, or analyze error,

epitomizes design oversight that disregards human factors

[19].

The objective of the present study was to demonstrate

that introduction of the trocarless TVC (method and instru-

ment) is a feasible, reproducible, and adoptable peritoneal

entry system. Closed primary entry requires 2 sharp instru-

ments inserted blindly into the peritoneum with no recourse.

Inasmuch as the Veress needle diameter is considerably

smaller than the trocar, they account for only 10% to

20% of entry injuries, and most require no repair. Although

several Veress needle insertion safety tests have been

described, the evidence favors a sustained Veress intraperi-

toneal pressure of 10 mm Hg or less as the most reliable

indicator of correct placement. A Canadian survey reported

that most gynecologists use the click sound test (82%) or

Veress intraperitoneal pressure of 10 mm Hg or less

(74.3%) to ascertain correct needle placement [10]. A sim-

ilar survey from the United Kingdom demonstrated that

only 9% of gynecologists use Veress intraperitoneal pres-

sure of 10 mm Hg or less exclusively as correct placement

Fig. 3. Primary umbilical port exit sequencing with the Endo-TIP trocarless threaded visual cannula after removal of ancillary ports under visual control and

desufflation of peritoneal cavity. A, Cannula realigned perpendicular to anterior rectus fascia with 0-degree laparoscope sheathed 1 cm short of the cannula

end. B, Counterclockwise rotation cascades peritoneal membrane off cannula outer thread. C, Further rotation reveals posterior rectus fascia and rectus muscle

fibers (asterisk). D, Anterior rectus fascia is then seen. E, Four port site layers clearly recognized to ensure absence of omentum-bowel lodged in port track. F, As

cannula disengages, abdominal wall tissues are observed to resume gridiron orientation, and intact rectus muscle shutter mechanism recoils to secure port com-

petence.

Ternamian et al. Trocarless Visual Laparoscopic Entry System 465

indicator, and an additional 62% used Veress intraperitoneal

pressure in conjunction with other tests to gauge placement

[9]. In the United Kingdom, 44% of gynecologists use 25

mm Hg of pneumoperitoneum exclusively [9]. Similarly,

45% of Canadian gynecologists demonstrated similar ten-

dencies; 28.8% use 20 to 25 mm Hg, and 16.2% use 16

to 19 mm Hg [10]. Gynecologists use the umbilical region

for insufflation because of training rather than evidence.

Inasmuch as most advocate use of the LUQ as a default

insufflation site, routine LUQ insufflation and entry is

advocated and practiced by some [8].

Transient high-pressure pneumoperitoneum has no lasting

cardiorespiratory effects in healthy women [20]. Reich et al

[21] first advocated 30 mm Hg HIP entry and encountered

3 primary trocar bowel injuries in 3451 procedures. Garry

[22] reported 1 injury in 3156 laparoscopies. Vilos et al

[14] encountered 1 injury in 2498 procedures, for a total of

5/9,10, or 0.06%. In all 5 injuries, bowel was densely adhered

to the parietal port site, and in such cases, visceral injury is

unavoidable.

Real-time visual primary entry enables error archiving and

replay capabilities for early mishap detection before

466 Journal of Minimally Invasive Gynecology, Vol 17, No 4, July/August 2010

irreparable harm is sustained. The single enterotomy was im-

mediately recognized and repaired, resulting in uneventful

recovery with no serious health or medicolegal conse-

quences. Inadvertent sudden desufflation resulted in loss of

abdominal wall and bowel visual cues (situational aware-

ness) contributing to injury.

No minor or major vascular injuries occurred since adopt-

ing the trocarless TVC. Our experience (Dr. Ternamian) with

this method and instrument in more than 1700 procedures has

been uneventful, with no serious bowel or vessel injuries. We

also observed that irrespective of gender and training, this

method seems less intimidating and is readily adoptable by

residents and fellows.

Since introduction of trocarless TVC ancillary cannulas,

we have encountered no abdominal wall vessel or visceral in-

juries. Although ancillary TVCs require both hands for inser-

tion, they are valuable during long surgeries because of their

secure anchoring capability and infrequent spontaneous ex-

trusions.

Three visual entry systems are now available including the

visual Veress needle, the single-use visual trocar, and the

multiple-use trocarless TVC. All published visual entry com-

plications involve disposable visual trocars and not the trocar-

less TVC [7,22–24]. Fundamental design and application

differences between the two preclude equating safety and

complications of one to the other. Knowledge of anatomy,

identification of navigational cues, and recognition of

monitor images (perceptual awareness) are all important for

safe deployment [15,25]. With consenting high-risk patients

(previous abdominal surgery, obesity, or adhesions), the

possibility of use of an alternate entry method (visual or

open), the probability of a different access site (LUQ), and

the likelihood of laparotomy must be discussed [7,26].

As the fundamentals of safe surgery are reviewed in gen-

eral and the mechanisms of inadvertent laparoscopic entry

injury are analyzed in particular, 5 important weaknesses

are readily identified: excessive penetration force; sharp, cut-

ting, pointed trocars; nonvisualization of the operative field

(blind trocar insertion); sudden loss of surgical instrument

or trocar control; and trocar overshoot. Our observations

and experience with conventional entry methods and the

re-engineered trocarless TVC design enables us to suggest

that it is a meaningful and reliable method of addressing the

peritoneal entry conundrum. It is suggested that observational

studies of adverse events provide information that is as valid

as evidence from randomized controlled trials. Some have

demonstrated that reporting of adverse effects in randomized

controlled trials is often inadequate and needs strengthening.

Far from detracting from the value of observational research,

it is now agreed that several sources of data are required to

better understand and assess health-related harm [27–29].

Conclusion

All operative methods are prone to risk, and peritoneal en-

try is no exception. Securing and maintaining ports while

averting injury remains a critical first step in laparoscopy.

We have demonstrated that use of the trocarless TVC is fea-

sible, reproducible, and adoptable, and enables surgeons to

heed safety cues and learn from mishaps.

References

1. Corson SL, Batzer FR, Gocial B, Maislin G. Measurement of the force

necessary for laparoscopic trocar entry. J Reprod Med. 1989;34:

282–284.

2. The President and the Press: Address before the American Newspaper Pub-

lishers Association. Available at: http://www.jfklibrary.org/Historical

1Resources/Archives/Reference1Desk/Speeches/JFK/003POF03News

paperPublishers04271961.htm. Accessed April 20, 2010.

3. Garry R. Surgeons may continue to use their chosen entry technique.

Gynecol Surg. 2009;6:87–92.

4. Chapron C, Fauconnier A, Coffinet F, et al. Laparoscopic surgery is not

inherently dangerous for patients presenting with benign gynecologic

pathology: results of a meta-analysis. Hum Reprod. 2002;17:

1334–1342.

5. Garry R. A consensus document concerning laparoscopic entry tech-

niques: Middlesbrough, March 19–20, 1999. Gynecol Endosc. 1999;8:

403–406.

6. Garry R. Towards evidence based laparoscopic entry techniques: clini-

cal problems and dilemmas. Gynecol Endosc. 1999;8:315–326.

7. Fuller J, Ashar BS, Carey-Corrado J. Trocar-associated injuries and fa-

talities: an analysis of 1399 reports to the FDA. J Minim Invasive Gyne-

col. 2005;12:302–307.

8. Vilos GA, Ternamian A, Dempster J, et al. Laparoscopic entry: a review

of techniques, technologies and complications. J Obstet Gynecol Can.

2007;29:433–447.

9. Varma R, Gupta JK. Laparoscopic entry techniques: clinical guideline,

national survey and medicolegal ramifications. Surg Endosc. 2008;22:

2686–2697.

10. Kroft J, Aneja A, Tyrwhitt J, Ternamian A. Laparoscopic peritoneal en-

try preferences among Canadian gynaecologists. J Obstet Gynecol Can.

2009;31:641–648.

11. Vilos GA, Vilos AG. Safe laparoscopic entry guided by Veress needle

CO2 insufflation pressure. J Am Assoc Gynecol Laparosc. 2003;10:

415–420.

12. Teoh B, Sen R, Abbott J. An evaluation of four tests used to ascertain

Veress needle placement at closed laparoscopy. J Minim Invasive Gyne-

col. 2005;12:153–158.

13. Azevedo OC, Azevedo JL, Sorbello AA, et al. Evaluation of tests per-

formed to confirm position of the Veress needle for creation of pneumo-

peritoneum in selected patients: a prospective clinical trial. Acta Cir

Bras. 2006;21:385–395.

14. Vilos GA, Vilos AG, Abu-Rafea B, et al. Three simple steps during

closed laparoscopic entry may minimize major injuries. Surg Endosc.

2009;23:758–764.

15. Ternamian A. Laparoscopic access. In: Jain N, editor. State of the Art

Atlas of Endoscopic Surgery in Infertility and Gynecology. New Delhi,

India: Jaypee Brothers Medical Publishers (P) Ltd; 2004. p. 22–35.

16. Ternamian AM. Laparoscopy without trocars. Surg Endosc. 1997;11:

815–818.

17. Glass KB, Tarnay CM, Munro MG. Intraabdominal pressure and inci-

sion parameters associated with a pyramidal laparoscopic trocar-

cannula system and the EndoTIP cannula. J Am Assoc Gynecol Lapa-rosc. 2002;9:508–513.

18. Vilos GA, Hancock G, Penava DA, Kozak I, Davies W. Nine cases of

bowel injury during 3472 laparoscopies. J Obstet Gynecol Can. 1999;

21:144–150.

19. Ternamian A. Port creation during laparoscopic hysterectomy. In:

Mettler L, editor. New Delhi, India: Jaypee Brothers Medical Publishers

(P) Ltd; 2007. p. 175–180.

Ternamian et al. Trocarless Visual Laparoscopic Entry System 467

20. Abu-Rafea A, Vilos GA, Vilos AG, et al. High-pressure laparoscopic en-

try does not adversely affect cardiopulmonary function in healthy

women. J Minim Invasive Gynecol. 2005;12:475–479.

21. Reich H, Robeiro SC, Rasmussen C, Rosenberg J, Vidali A. High-pres-

sure trocar insertion technique. J Soc Laparoendosc Surg. 1999;3:

45–48.

22. Garry R. Complications of laparoscopic entry. Gynecol Endosc. 1997;6:

319–329.

23. Corson SL, Chandler JG, Way LW. Survey of laparoscopic entry in-

juries provoking litigation. J Am Assoc Gynecol Laparosc. 2001;8:

341–347.

24. Bhoyrul S, Vierra MA, Nezhat Cr, Krummel TM, Way LW. Trocar in-

juries in laparoscopic surgery. J Am Coll Surg. 2001;192:677–683.

25. String A, Berber E, Foroutani A, Macho JR, Pearl JM, Siperstein AE.

Use of the optical access trocar for safe and rapid entry in various lapa-

roscopic procedures. Surg Endosc. 2001;15:570–573.

26. Sharpe HT, Dodson MK, Draper ML, Watts DA, Doucette RC,

Hurd WW. Complications associated with optical-access laparoscopic

trocars. Obstet Gynecol. 2002;99:553–555.

27. Vandenbroucke JP. When are observational studies as credible as ran-

domized trials? Lancet. 2004;363:1728–1731.

28. Ioannidi JP, Lau J. Improving safety reporting from randomized trials.

Drug Safety. 2002;25:77–84.

29. Loke YK, Derry S, Aronson JK. A comparison of three different sources

of data in assessing the frequency of adverse reactions to amiodarone. Br

J Clin Pharmacol. 2004;57:616–621.