VIDEOS

‘‘Triangle of safety’’: anatomic considerations in transvaginalnatural orifice surgery

Kurt Roberts • Daniel Solomon • Robert Bell •

Andrew Duffy

Received: 12 September 2012 / Accepted: 19 October 2012 / Published online: 4 May 2013

� Springer Science+Business Media New York 2013

Abstract

Background The introduction of transvaginal (TV) natu-

ral orifice transluminal endoscopic surgery (NOTES)

brings the loss of traditionally used cutaneous landmarks

for safe peritoneal access. This video describes the use of

landmarks within the posterior vaginal fornix to define a

‘‘triangle of safety’’ wherein the peritoneal cavity can be

accessed while minimizing the risk of injury to surrounding

structures.

Methods The triangle of safety is best identified in the

following way. The cervix and posterior fornix are visu-

alized. Then an imaginary clock located at the base of the

cervix is envisioned. The superior two corners of the tri-

angle are represented by the 4 and 8 o’clock positions on

this imaginary clock. Sometimes the cervix needs to be

grasped and elevated anteriorly so that the inferior apex of

the triangle delineated by the center of the rectovaginal

fold is better visualized.

Results During hybrid TV NOTES, the rectovaginal

pouch of Douglas is visualized from the umbilicus, and the

vaginal port can then be safely passed through the center of

the triangle. It is important that the vaginal port should be

angled upward, aiming toward the umbilicus to avoid

injury to the rectum. During pure TV NOTES, the incision

is made with electrocautery from the 5 o’clock position to

the 7 o’clock position within the triangle. The peritoneum

is sharply entered, and the colpotomy is dilated with the

surgeons’ fingers.

Conclusions The triangle of safety defines a set of land-

marks between the base of the cervix and the rectovaginal

fold. It allows for a safe TV access for hybrid and pure TV

NOTES while minimizing the risk of injury to surrounding

structures.

Keywords Complications � Natural orifice surgery �NOTES � Transvaginal

Through an open incision, a surgeon achieves both tactile

feedback and depth perception. Traditional surgical lapa-

roscopy minimizes incisions with the corequisite loss of

tactile feedback and depth. This trade-off is taken one step

further with the introduction of transvaginal (TV) natural

orifice transluminal endoscopic surgery (NOTES) because

the loss of percutaneous incisions brings the loss of cuta-

neous landmarks for safe peritoneal access. This video

illustrates the use of landmarks within the posterior vaginal

fornix to define a ‘‘triangle of safety’’ wherein the perito-

neal cavity can be accessed while minimizing the risk of

injury to surrounding structures.

The utilization of anatomic landmarks to safely define

structures and minimize the risk of injury is part and parcel

to minimally invasive surgery. Introduced in 1994, the

‘‘critical view of safety’’ improved the performance of

laparoscopic cholecystectomy by identifying landmarks

within the absence of tactile and 3D cues to identify the

cystic duct and thereby avoid inadvertent injury to the

common bile duct [1]. Similarly, the ominous ‘‘triangle of

doom’’ delineates the anatomic landmarks that should not

be dissected or tacks placed during a totally extraperitoneal

herniography [2]. The triangle of safety is a similar set of

Electronic supplementary material The online version of thisarticle (doi:10.1007/s00464-013-2864-0) contains supplementarymaterial, which is available to authorized users.

K. Roberts (&) � D. Solomon � R. Bell � A. Duffy

Section of Surgical Gastroenterology, Department of Surgery,

Yale University School of Medicine, 40 Temple Street, Suite 7B,

New Haven, CT 06510, USA

e-mail: kurt.roberts@yale.edu

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Surg Endosc (2013) 27:2963–2965

DOI 10.1007/s00464-013-2864-0

and Other Interventional Techniques

landmarks through which a colpotomy can be safely made

into the peritoneum for pure TV NOTES or under visual-

ization from an umbilical port for hybrid TV NOTES.

Methods

Patient positioning

As previously described [3], patients are placed in a low

lithotomy position in Allen stirrups after the induction of

general endotracheal anesthesia. The operating surgeon

stands between the patient’s legs while the scrub nurse

assists from behind with the laparoscopic screen positioned

above the patient’s abdomen. In cases of pure TV NOTES,

the assistant joins the operating surgeon at the foot of the

table. In hybrid TV NOTES, the assistant operates the

transumbilical instruments from the patient’s left side. The

abdomen, pelvis, and vaginal canal are disinfected with the

appropriate surgical disinfectant. With the patient placed in

the steep Trendelenburg position, a weighted speculum is

introduced into the vagina, allowing for visualization of the

cervix. The cervix is then grasped with a single-toothed

tenaculum and retracted anteriorly.

Triangle of safety

The triangle of safety is best identified in the following

way. The cervix and posterior fornix are visualized. Then a

clock located at the base of the cervix is envisioned. The

superior two corners of the triangle are represented by the 4

and 8 o’clock positions. Sometimes the cervix needs to be

grasped and elevated anteriorly, so that the inferior apex of

the triangle delineated by the center of the rectovaginal

fold is better visualized (Figs. 1, 2). Similarly, on the

internal (umbilical) view of the triangle of safety, the

uterosacral ligaments mark the two upper corners, and

the center of the rectovaginal fold marks the inferior corner

of the triangle of safety (Fig. 3).

Surgical incision

During hybrid NOTES, the rectovaginal pouch of Douglas

is visualized from the umbilicus, and the vaginal port can

then be passed through the center of the triangle. It is

important that the vaginal port should be angled upward,

aiming toward the umbilicus, to avoid injury to the rectum.

During pure TV NOTES, the incision in made with elec-

trocautery from the 5 o’clock position to the 7 o’clock

position within the triangle. The peritoneum is sharply

entered, and the colpotomy is dilated with the surgeons’

fingers.

Closure

After the completion of the surgery, the colpotomy is

closed with a single running braided absorbable suture

under direct visualization. The patient is instructed to

refrain from sexual intercourse for 2 weeks.

Discussion

The posterior fornix of the vagina is well suited for NOTES

because it is neither somatically innervated nor enveloped

in fascia. The posterior vaginal fornix is bordered laterally

by the uterosacral ligaments, posteriorly by the rectovagi-

nal septum, and anteriorly by the floor of the cervical canal

Fig. 1 Drawing of the triangle of safety (thick dashed blue triangle).

The two upper corners are at 4 and 8 o’clock of the imaginary clock

of the base of the cervix (dashed black circle), and the third inferior

corner is at the center of the rectovaginal fold

Fig. 2 Typical vaginal view of the triangle of safety

2964 Surg Endosc (2013) 27:2963–2965

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[4]. A colpotomy through the triangle of safety minimizes

the risk of injury to the surrounding vital structure,

including the bladder anteriorly, the rectum posteriorly,

and the ureters that travel along the base of the cervix at 3

and 9 o’clock positions of the imaginary clock.

Conclusion

The triangle of safety defines a set of landmarks between

the base of the cervix and the rectovaginal fold that allows

for safe TV access for pure and hybrid TV NOTES while

minimizing the risk of injury to surrounding structures.

Disclosures Dr. Roberts has intellectual property rights and equity

in NovaTract. Drs. Solomon, Bell, and Duffy have no conflicts of

interest or financial ties to disclose.

References

1. Strasberg SM, Hertl M, Soper NJ (1995) An analysis of the

problem of biliary injury during laparoscopic cholecystectomy.

J Am Coll Surg 1:101–125

2. Spaw AT, Ennis BW, Spaw LP (1991) Laparoscopic hernia repair:

the anatomic basis. J Laparoendosc Surg 5:269–277

3. Roberts KE, Solomon D, Mirensky T, Silasi DA, Duffy AJ,

Rutherford T, Longo WE, Bell RL (2012) Pure transvaginal

appendectomy versus traditional laparoscopic appendectomy for

acute appendicitis: a prospective cohort study. Ann Surg 2:266–269

4. Nichols DH, Clynde RL (1989) Vaginal surgery. Williams &

Wilkins, Baltimore

Fig. 3 Umbilical view of port placement within the triangle of safety

(dashed blue triangle)

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