Using external magnet guidance and endoscopically placedmagnets to create suture-free gastro-enteral anastomoses

Christopher Myers • Benjamin Yellen •

John Evans • Eric DeMaria • Aurora Pryor

Received: 13 May 2009 / Accepted: 2 October 2009 / Published online: 24 December 2009

� Springer Science+Business Media, LLC 2009

Abstract

Background To facilitate endolumenal and natural orifice

procedures, this study evaluated a novel technique using

external and endoscopically placed magnets to create

suture-free gastroenteral anastomoses.

Methods Seven anesthetized adult swine underwent

endoscopic placement of magnets into the small bowel and

stomach. Using external magnets, the endoscopically placed

internal magnets were brought into opposition under endo-

scopic view. After 1–2 weeks, the pigs were killed and

analyzed. At laparotomy and under sterile conditions, peri-

toneal cultures were obtained. The anastomoses were

evaluated endoscopically and tested using an air insufflation

test. Finally, the anastomoses were resected and evaluated

microscopically.

Results The average operative time for endoscopic

placement of the magnets was 34.3 ± 14.8 min. Successful

placement and creation of anastomoses occurred in six of

the pigs. One pig did not form an anastomosis because the

magnets were too large to pass through the pylorus at the

time of attempted magnet placement. Six swine experi-

enced uncomplicated postoperative courses. One pig’s

postoperative course involved constipation for several

days, requiring additional fluids and fiber supplementation.

The findings at endoscopy showed that the magnets were

adhered to the anastomosis, which were easily freed, or

within the stomach. The air insufflation test results were

negative for all the pigs. At laparotomy, there was no

evidence of infection, abscess, or leak, but two peritoneal

culture results were positive with scant growth of Staphy-

lococcus aureus and coagulase-negative staphylococcus,

presumably contaminants. Microscopically, the anastomo-

ses illustrated granulation and fibrous connective tissue

without evidence of infection or leak.

Conclusion Endoscopically placed magnets with external

magnet guidance is a feasible and novel approach to cre-

ating patent gastroenteral anastomoses without abdominal

incisions or sutures.

Keywords Endoscopy � Gastrojejunal anastomosis �Magnetic instrumentation � NOTES � Stapleless

anastomosis

General surgery has transitioned from maximal to minimal

invasiveness with the development of natural orifice trans-

lumenal endoscopic surgery (NOTES) and endolumenal

C. Myers (&)

Department of Surgery, Duke University Medical Center,

Durham, NC, USA

e-mail: chrismyers2@hotmail.com

B. Yellen

Department of Mechanical Engineering and Material

Science, Pratt School of Engineering, Duke University,

Durham, NC, USA

J. Evans

Department of Gastroenterology, Wake Forest University

Baptist Medical Center, Winston-Salem, NC, USA

E. DeMaria

Department of Endosurgery, Duke University,

Durham, NC, USA

E. DeMaria � A. Pryor

Department of Surgery, Duke University,

Durham, NC, USA

Present Address:C. Myers

UPMC St. Margaret’s, University of Pittsburgh Medical Center,

Pittsburgh, PA, USA

123

Surg Endosc (2010) 24:1104–1109

DOI 10.1007/s00464-009-0735-5

procedures. We sought to develop a completely endoscopic

procedure to avoid the risk of contaminating the peritoneal

cavity or leak from the enterotomy, which can occur when

the gut wall is crossed during NOTES.

The idea of using magnets and compression necrosis to

create anastomoses within the bowel developed from two

previously published concepts. First, in 1892, Dr. John B.

Murphy [1] developed the ‘‘Murphy button,’’ which con-

sisted of two metal mushroom-shaped devices sutured in

two ends of the bowel. The stems from the two ends of the

bowel were brought together, leading to compression

necrosis of the soft tissues between the metal devices,

creating an anastomosis [1, 2].

Second, young children experienced the development

patent fistulas within the bowel after consuming multiple

magnets in one setting. These fistulas were the result of

compression necrosis between attracting magnets as they

passed through the gastrointestinal tract [3–6].

Combining these two concepts led us to believe that a

patent sutureless anastomosis could be created via com-

pression necrosis between specifically placed magnets

within the bowel. In a preliminary study, we tested this idea

through a porcine model by placing and attracting differ-

ent-shaped magnets in the stomach and the jejunum via

laparotomy to determine feasibility. After 1 week of sur-

vival, patent anastomoses were created using ring-shaped

magnets [7]. In the current experiment, we sought to

expand this idea to an entirely endolumenal approach by

attempting to place the magnets endoscopically and using

external magnets to attract the internal magnets, avoiding

other visceral involvement.

Materials and methods

Sutureless gastroenteral anastomoses were created using

endoscopically placed ring-shaped magnets in swine under

institutional animal care and use committee (IACUC)

approval.

Magnets

Two types of neodymium (NdFeB) grade N42, nickel-

plated magnets (K & J Magnetics, Jamison, PA, USA)

were placed endoscopically into the small bowel and

stomach (Fig. 1). The first type was a large-ring magnet (3/

4-in. outer diameter [OD] 9 1/2-in. inner diameter

[ID] 9 3/8-in.-thick ring; Fig. 1A). The second type was a

small-ring magnet (1/2-in. OD 9 1/4-in. ID 9 1/8-in.

thick ring; Fig. 1B). The large magnets were used for better

attractive force and more successful anastomoses than in

the preliminary experiments. The smaller magnets were

used for facile traversing of the pyloris.

The small-ring magnets were placed in four swine and

the thick-ring magnets in three swine. Two large-block

NdFeB magnets (1 in. wide 9 1/2 in. thick 9 2 in. long)

were used externally.

Operative procedure

Stage 1: magnet placement

Seven Yorkshire crossbred adult swine weighing 25–

35 kg underwent placement of magnets. The animals were

fasted with access to water 12 h before induction of

anesthesia. For perioperative pain control, a fentanyl

patch (50 lg) was placed 24 h preoperatively. A combi-

nation of acepromazine (1.1 mg/kg) and ketamine

(22 mg/kg) via intramuscular (IM) injection and isoflu-

rane (1–3%) via face mask were used for induction and

intubation.

Once the animals were intubated, anesthesia and venti-

lation were maintained using isoflurane (1–3%) and oxygen

with tidal volumes of 10 ml/kg and respiratory rates of 15

to 20 breaths per minute (bpm). Ampicillin (1 g, IM) and

Fig. 1 A Thick ring (3/4-in. outer diameter [OD] 9 1/2-in. inner

diameter [ID] 9 3/8-in. B Small ring (1/2-in. OD 9 1/4-in. ID 9 1/

8-in.). Neodymium magnets were placed endoscopically in the

stomach and the jejunum of swine to form sutureless anastomoses

Surg Endosc (2010) 24:1104–1109 1105

123

Baytril (2.5 mg/kg, IM) were administered preoperatively

and daily throughout the study, per IACUC standards.

Once the animals had been anesthetized in supine

position, a single-channel endoscope (Pentax, Montvale,

NJ, USA) was introduced transorally into the pig’s jeju-

num. Under direct visualization, a 0.035-in. Jagwire Super

Stiff Guidewire (Boston Scientific, Natick, MA, USA) was

passed deep into the small bowel. The endoscope was

removed from the pig, with the guidewire left in place.

Outside the pig, the guidewire was passed through a ring

magnet and eventually through the channel of the endo-

scope. The endoscope was used to push the magnet into the

stomach by passing it over the guidewire.

Once the magnet was in the stomach, a 0.035-in. DU-

RAglide stone removal balloon catheter (BARD, Cov-

ington, GA, USA) was passed over the guidewire and

through the endoscope and ring magnet. Inflation of the

balloon within the ring of the magnet established control

of the magnet for its passage it over the guidewire and

into the small bowel (Fig. 2). Desufflation of the balloon

allowed visualization through the magnet and into the

small bowel.

Once the magnet was properly positioned in the jeju-

num, one large-block magnet was placed on the pig’s

abdomen, attracting the ring magnet and pulling the small

bowel up to the anterior abdominal wall (Fig. 3). After

placement and attraction were confirmed with the endo-

scope, the scope and balloon were removed. A second

magnet was placed into the stomach the same way and

attracted to the anterior abdominal wall with a second

large-block magnet. The two external magnets then were

brought together, attracting the internal magnets together

as well. The scope, guidewire, and balloon then were

removed.

The animals were allowed food and water immediately

after the operation and recovery from anesthesia. All the

pigs survived for at least 7 days (range, 7–14 days). Eating,

drinking, bowel, and behavior habits were observed.

Stage 2: reexploration and killing

The swine were killed 7 to 14 days after the initial oper-

ation using an intravenous lethal injection of Euthasol

(Virbac, AH, Inc., Fort Worth, TX) (175 mg/kg). Imme-

diately after the animals were killed, an endoscope was

inserted into the stomach to locate the magnets and

examine the anastomosis and surrounding mucosa.

Once the anastomosis was evaluated endoscopically, the

animal was prepped, draped, and explored via laparotomy.

Anaerobic and aerobic peritoneal cultures were obtained

immediately at the entrance to the abdominal cavity.

Attention was particularly guided toward the anastomosis

and any evidence of obstruction, leak, or infection. The

stomach was submerged in saline, and a leak test was

performed using unregulated endoscopic insufflation.

Finally, the gastrojejunostomy was excised, with preser-

vation of the involved parts of the stomach and the afferent

and efferent limbs of the jejunum.

Gross and microscopic examinations of the specimens

were performed. Masson trichrome stain was used because

it allows easy identification of mucosal injury and inflam-

matory response.

Fig. 2 The small-ring magnet was controlled and placed into the

small bowel using the Duraglide stone removal balloon catheter over

a guidewire

Fig. 3 External magnets used to attract internal magnets and bowel

to the anterior abdominal wall, avoiding other intraabdominal viscera.

Once attracted to the anterior abdominal wall, the external magnets

are brought together, also bringing together the two internal magnets

1106 Surg Endosc (2010) 24:1104–1109

123

Results

The average time for endoscopic magnet placement was

34.3 ± 14.8 min (range, 20–60 min). All the pigs survived

the postoperative course. One pig experienced a delay in

bowel function despite normal eating, drinking, and

behavioral activities. An abdominal X-ray on postoperative

day 6 showed the entire colon with mild distention and

stool, suggesting ileus/constipation. With additional

hydration and fiber supplementation, this pig resumed

normal bowel function.

Six pigs experienced successful placement of the mag-

nets and creation of gastrojejunal anastomoses. One pig

failed to produce an anastomosis because it could not pass

the thick-ring magnet through the pylorus. At endoscopy,

the magnets were found either within the anastomosis and

easily freed with minimal pressure or within the stomach.

All anastomoses were easily intubated by the endoscope

(Figs. 4, 5) and found to be negative for leak via an

unregulated air insufflation test. Laparotomy showed no

evidence of leak, infection, or obstruction. Two peritoneal

cultures tested positive with scant growth of Staphylococ-

cus aureus or coagulase-negative staphylococcus. Due to a

lack of evidence of inflammation/infection at laparotomy

and the absence of enteric organisms, these cultures were

presumed to be contaminants. Microscopically, the anas-

tomoses illustrated granulation and fibrous connective tis-

sue without evidence of infection (Fig. 6).

Discussion

This study is the first in the English literature to suggest

that by using endoscopically placed magnets via com-

pression necrosis, a sutureless patent anastomosis can be

created in living animals. As discussed in our preliminary

study, this is not the initial study describing compression

necrosis as a means to create an anastomosis. Murphy [1]

reported the ‘‘Murphy button’’ in 1892. Swain and Mills

used plastic rings to create enterocutaneous anastomoses in

dogs [7]. Multiple published studies have described a sta-

pling device, the biodegradable anastomotic ring (BAR),

which placed biodegradable rings in the colon, creating an

anastomosis [8].

Enteric magnet use and technology were first described

by Cope and colleagues, who created anastomoses by

compression necrosis in dogs, pigs, and eventually humans

[7]. Erdmann et al. [9] used magnet technology to create

sutureless vascular anastomosis. Magnets have been used

to treat malignant and biliary duct strictures after liver

transplantation [10, 11].

Fig. 4 Endoscopic view of a patent gastrojejunostomy created by

compression necrosis between magnets

Fig. 5 A patent gastrojejunostomy created by small magnets in a

gross specimen extracted from a pig. The Debakey ‘‘pickups’’ pass

through the jejunum

Fig. 6 Microscopic examination using Masson trichrome dye

preparation showing granulation and fibrous connective tissue at a

patent sutureless anastomosis without evidence of leak or infection

Surg Endosc (2010) 24:1104–1109 1107

123

In our preliminary study, we were able to place magnets

in the jejunum and stomach via laparotomy, creating patent

sutureless anastomoses [7]. In this study, we proved that

patent sutureless anastomoses can be created via a com-

pletely endolumenal approach.

The materials used and the technique for placement of

the magnets underwent change throughout our experiment.

The magnets used were based on our preliminary study, in

which the small-ring and thick-ring magnets produced

large patent anastomoses. The small-ring magnets exhib-

ited an attracting force of 636 mmHg (assuming a constant

intervening tissue layer of 2 mm) and a patent but small

anastomosis after 14 days. They were not found after the

animals were killed, suggesting passage through the gas-

trointestinal tract [12]. When an additional magnet was

added (total of two magnets in the jejunum and two in the

stomach), the resultant anastomoses appeared to be larger,

and the magnets were found in the stomach. Additional

studies are needed to determine whether a difference really

exists in the size of the anastomoses given that the diameter

of the ring did not change and that only the attractive force

changed by placement of an additional magnet on each

side. The size of two magnets together versus four magnets

would imply that the smaller the size of magnets, the easier

they pass through the gastrointestinal tract.

Thick-ring magnets produced a large patent anastomosis

but were difficult to place. The thick-ring magnets showed

an attractive force of 940 mmHg (assuming a constant

intervening tissue layer of 2 mm), produced a large patent

anastomosis, and were found in the stomach [12]. Due to

its size, transporting the magnet past the endotracheal tube

and through the pylorus was difficult. The thick-ring

magnet would not go through the pylorus in one pig and

therefore failed to create an anastomosis. A hole was

drilled in the sides of the magnet to allow passage of the

wire with better control, but difficulties still were experi-

enced due to a lack of change in diameter. After creation of

the anastomosis, the magnets were always found in the

stomach. Longer-term studies are needed to evaluate

alternative magnet configurations, passage of attracted

thick-ring magnets through the gastrointestinal tract, and

consideration of an endoscopic retrieval procedure.

Our technique of using a guidewire to place enteric

magnets was previously reported by Cope [13]. He

described blind transoral wire placement of magnets,

which resulted in intraabdominal visceral trapping

between magnets and a lack of anastomosis creation. His

technique was modified in several ways to identify the

location of our anastomosis and to avoid visceral entrap-

ment. We used a balloon catheter to control the magnet

placement and an endoscope to place the guidewire and

magnets visually into proper position. Once the magnet

was placed into the small bowel, external magnets were

used to draw the magnet and small bowel to the anterior

abdominal wall. When the magnet was placed in the

stomach, again, an external magnet was used to attract the

magnet and stomach to the anterior abdominal wall.

Bringing the two external magnets together brought the

two internal magnets together, with the idea of avoiding

other intraabdominal viscera. Because there was no evi-

dence of impinging other intraabdominal viscera at lapa-

rotomy, our technique was successful.

Due to the endoscopic approach to this procedure,

postoperative care and recovery are minimal. All the pigs

were allowed to eat and drink immediately after recovery

from anesthesia. One pig did experience a delay in bowel

function despite normal eating and behavior. On postop-

erative day 6, due to concerns for involvement of other

intraabdominal viscera, an abdominal X-ray was obtained,

which showed stool throughout a mildly dilated colon

without evidence of free air or obstruction. With addi-

tional water and fiber, bowel function returned later that

day. The remainder of the pig’s postoperative course was

uncomplicated.

At endoscopy, four small-ring magnets were found in

the stomach and a large patent anastomosis created

between the stomach and the small bowel. At laparotomy,

an anastomosis was found between the stomach and the

jejunum just beyond the ligament of Treitz. There was no

evidence of involvement of other bowel, obstruction,

infection, abscess, or leak. Peritoneal culture results were

negative. Despite this occurrence, all the other pigs had a

completely uneventful postoperative course.

Two peritoneal cultures were positive with contami-

nants. Scant growth of Staphylococcus aureus and coagu-

lase-negative staphylococcus was obtained from the pigs

with small- and thick-ring magnets. Because these bacteria

are not of enteric origin, all air insufflation test results were

negative for leak, and there was no evidence of infection at

exploration and microscopic examination. These positive

cultures are considered contaminants.

Daily antibiotics given throughout the entire postoper-

ative course may interfere with culture results, but there

would be evidence of infection if it truly were present. The

antibiotics were administered in our study based on local

IACUC standards. Because there was no intraabdominal

evidence of infection or leak, contamination of these cul-

tures was presumed to occur at the time of killing.

Microscopic examination of the anastomoses suggests

granulation and fibrous connective tissue without evidence

of infection.

These findings are similar to those from a sutured or

stapled anastomosis. As discussed in our preliminary study,

the long-term patency of the anastomoses needs to be

tested. Cope [13] reported anastomotic stricturing and

closure within 30 days of magnet placement in swine.

1108 Surg Endosc (2010) 24:1104–1109

123

In our study, all anastomoses were widely patent at 7

and 14 days. It is possible that the size of the anastomosis

and hence the magnet may contribute to stricture, just as

seen with current circular staplers. Also, the swine stomach

is prone to remodeling of itself. Therefore, studies with

other species, such as canines, may be indicated.

This study suggests that sutureless patent anastomoses

may be created via a completely endolumenal approach

using endoscopically placed enteric magnets with external

magnetic guidance. With the future of surgery focusing on

NOTES and endolumenal procedures, this approach may

be used in any operation that requires an anastomosis as

long as the magnets can be placed safely. Because the

procedure is completely endoscopic and may require only

conscious sedation, possibilities of performing the opera-

tion on an outpatient basis in an endoscopy suite for high-

risk surgical candidates may be entertained.

Disclosures Christopher Myers, John Evans, and Benjamin Yellen

have no conflicts of interest or financial ties to disclose. Eric DeMaria

receives Covidien, Stryker, and Ethicon educational grants as well as

Affinergy and Covidien honorariums. Dr. Pryor has ownership

interests in Transenterix and Barosense. Aurora Pryor also is a

speaker for Covidien and Olympus and a consultant for Covidien,

Olympus, Gore, Transenterix, and Immersion.

References

1. Murphy J (1892) Cholecysto-intestinal, gastrointestinal, entero-

intestinal anastomosis and approximation without sutures (origi-

nal research). Med Rec N Y 42:665–676

2. Dawbarn RH (1895) VI. The relative value of the murphy button

and absorbable plates in intestinal anastomosis. Ann Surg 21:

166–172

3. Alzahem AM, Soundappan SS, Jefferies H, Cass DT (2007)

Ingested magnets and gastrointestinal complications. J Paediatr

Child Health 43:497–498

4. Palanivelu C, Rangarajan M, Rajapandian S, Vittal SK, Mah-

eshkumaar GS (2007) Laparoscopic retrieval of ‘‘stubborn’’ for-

eign bodies in the foregut: a case report and literature survey.

Surg Laparosc Endosc Perctan Tech 17:528–531

5. Dutta S, Barzin A (2008) Multiple magnet ingestion as a source

of severe gastrointestinal complications requiring surgical inter-

vention. Arch Pediatr Adolesc Med 162:123–125

6. Robinson AJ, Bingham J, Thompson RL (2009) Magnet-induced

perforated appendicitis and ileocaecal fistula formation. Ulster

Med J 78:4–6

7. Myers CJ, DeMaria EJ, Mutafyan GA, Bauer MS, Evans JA,

Yellen B, Pryor AD (2009) Sutureless endolumenal gastro-jejunal

anastomosis creation using magnets. Surg Innov (in press)

8. Kaidar-Person O, Rosenthal RJ, Wexner SD, Szomstein S, Person

B (2008) Compression anastomosis: history and clinical consid-

erations. Am J Surg 195:827–828

9. Erdmann D, Sweis R, Heitmann C, Yasui K, Olbrich KC, Levin

LS, Sharkawy AA, Klitzman B (2004) Side-to-side sutureless

vascular anastomosis with magnets. J Vascular Surg 40:505–511

10. Avaliani M, Chigogidze N, Nechipai A, Dolgushin B (2009)

Magnet compression biliary-enteric anastomosis for palliation of

obstructive jaundice: initial clinical results. J Vasc Interv Radiol

20:614–623

11. Mita A, Hashikura Y, Masuda Y, Ohno Y, Urata K, Nakazawa Y,

Ikegami T, Terada M, Yamamoto H, Miyagawa S (2008) Non-

surgical policy for treatment of bilioenteric anastomotic stricture

after living donor liver transplantation. Transpl Int 21:320–327

12. Panofsky WKH, Philips M (1955) Classical electricity and

magnetism. Addison Wesley, New York

13. Cope C (1995) Creation of compression gastroenterostomy by

means of the oral, percutaneous, or surgical introduction of mag-

nets: feasibility study in swine. J Vasc Interv Radiol 6:539–545

Surg Endosc (2010) 24:1104–1109 1109

123