Engineering, 2013, 5, 10-14
doi:10.4236/eng.2013.55B003 Published Online May 2013 (
Pseudobezoars: Technology Progress and
New Prospects as a Medical Platform
Orly Yadid-Pecht1, Martin P. Mintchev1,2
1Department of Electrical and Computer Engineering, University of Calgary, Calgary, Canada
2Department of Surgery, University of Alberta, Edmonton, Canada
Received 2013
In recent years, pseudobezoars have been a subject of research, mainly serving as a basis for a new non-invasive alter-
native to obesity treatment. A pill incorporating the technology has been proven to be successful as a weight loss ther-
apy. It enables patients to sustain a diet longer, due to an increase in the level of satiety, resulting in a smaller amount of
food intake. Utilization of the tech nology has recently found new prospects in another organ of the GI tract, the colon.
Pseudobezoar technology can be utilized as an enhanced method for colon cancer screening and also as an alternative
carrier for bacterial therapy.
Keywords: Pseudobezoars; Obesity; Colon Cancer Screening; Diagnostic Device; Therapeutic Device
1. Introduction
The pseudobezoar technology is relatively new and only
recently has been granted a US patent [1]. However,
early successes of utilizing the device as a dietary pill
have already been reported [2-4]. The technology com-
prises a pill coated and targeted for the stomach, where
the shell dissolves and the superabsorbent polymer gran-
ules within expanding due to the contact with and ab-
sorption of gastric liquid. The granules are kept in the
stomach without an option to exit, since they are con-
tained in a gauze that disintegrates only after a few days.
Taking the pill in a prescribed regimen, demonstrated a
significant weight loss in a double blind study [3]. These
results confirmed the efficacy of the technology as a die-
tary pill targeted at the stomach.
We have recently described an additional possibility
for usage of the technology, targeting the colon as the
organ of choice. The method comprises use of the pseu-
dobezoar as a colon cancer screening device when taken
as a colon-targeted pill.
Section 2 will describe the current colon cancer
screening options. Section 3 will describe the utilization
of pseudobezoars as an alternative to current colon can-
cer screening technologies. Section 4 will briefly outline
the prospects of the utilizatio n of the device as a bacterial
transplant and summarize this p ape r.
2. Current Colon Cancer Screening Options
Colon cancer is the most common gastrointestinal (GI)
malignancy and the second leading cause of cancer deaths
in the United States [5]. Of the many pre-neoplastic and
neoplastic condition s in humans, nowh ere is the ability to
prevent disease as profound as it is in colon cancer [6].
Strategies for prevention have evolved over the past 15
years, now including the use of fecal occult blood test
(FOBT), fecal immunology tests (FIT), fecal DNA tests,
colonoscopy, video capsule endoscopy (VCE), and
computed tomographic (CT) colonography, also known
as Virtual Colonoscopy [7].
2.1. Fecal Occult Blood Tests
Although improved fecal occult blood tests have been
utilized, the overall sensitivity of this approach is not
impressive. In a 2005 study [8] Morikawa et al con-
cluded that the sensitivity of 1-time immunochemical
FOBT for detecting advanced neoplasia and invasive
cancer was 27.1% and 65.8%, respectively. In addition,
the sensitivity for invasive cancer detection according to
Dukes’ stages showed 50.0% for Dukes’ stage A, 70.0%
for Dukes’ stage B, and 78.3% for Dukes’ stages C or D
[9]. The sensitivity for detecting advanced neoplasia in
the proximal colon was significantly lower than that de-
tected in the distal colon (1 6. 3% vs 3 0.7%, p < 0.00007).
2.2. Fecal Immunology Tests
This testing method can be considered a refinement, ex-
tension and an additive improvement over the traditional
fecal occult blood testing. It has been reported that when
Copyright © 2013 SciRes. ENG
a routine fecal occult blood test (e.g. a sensitive guaiac
test) is combined with an immunological test for human
haemoglobin, the sensitivity improves to 97% (only 3%
false negative results) in patients and no false positiv es in
controls [10]. Another far more comprehensive study [11]
found that the sensitivity of the combined test was the
highest among all occult blood tests (in the range of
80%), and its specificity for detecting cancer was above
97%. The problem of all fecal occult blood tests, how-
ever, is that they aim at discovering blood in the feces
resulting from existing bleeding colorectal lesions, while
adenomatous polyps in asymptomatic average-risk adults
remain undetected. Therefore, by the time findings are
obtained with the fecal tests, it is usually too late [12,13].
Nevertheless, the use of either annual or biennial fecal
occult-blood testing significantly reduces the risk of co-
lorectal cancer [14].
2.3. Fecal DNA Tests
Oncogene mutations that characterize colorectal neopla-
sia are detectable in exfoliated ep ithelial cells in the stoo l.
Whereas neoplastic bleeding is intermittent making the
detection of occult fecal blood more or less random,
epithelial shedding is continual, potentially making fecal
DNA testing more sensitive. Early 21st century reports
indicated that a fecal DNA test had a sensitivity of 91
percent for the detection of colorectal cancer and 82 per-
cent for the identification of adenomas[15]. However,
one other report indicated that fecal DNA testing did not
improve dramatically the preventive early detection of
colon cancer compared to occult fecal blood testing [16].
2.4. Colonoscopy
Traditional colonoscopy has been considered the gold
standard for assessing colonic abnormalities, offering
sensitivity and specificity in detecting polyps exceeding
90%. Moreover, it also offers the ability to remove polyps
during the procedure. Although classical colonoscopy
can be considered safe, reliable, real-time and quick, re-
cent population-based studies have demonstrated that the
rate of protection against colorectal cancer that it offers
was only 30% to 50% [17]. In addition, colonoscopy is
an invasive procedure, performed in a hospital setting,
requires extensive and expensive logistic preparations,
carries substantial risks of harming patien ts (2 -4/100 0), is
heavily operator-dependent, and requires post-procedural
recovery [18,19].
2.5. Video Capsule Endoscopy
Orally administered video capsule endoscope(VCE) is a
simple, safe, non-invasive, and non-sedation requiring
procedure. VCE is well accepted and tolerated by the
patients and allows complete exploration of the small
bowel. Usually, it takes 24 to 48 hours for a VCE to pass
through the entire GI tract as a result of its passive
movement from mouth to anus [20]. In view of the fact
that the movement of these capsules is controlled by
spontaneous gut peristalsis, the application of VCE is
currently limited to small-lumen organs [21]. In larger-
lumen organs, such as the stomach or the colon, the cap-
sules tend to tumble, which leads to incorrect recognition
of a given organ segment by the capsule imaging system,
thus rendering the images unsuitable for diagnostic pur-
poses and a miss rate in the colon exceeding 30% [22].
In addition, rapid colonic motility could result in in-
complete imaging considering that most of the commer-
cial CEs are designed to acquire images at a pre-fixed
frame rate, usually 2 frames per second (FPS) [23].
Moreover, tumbling movement by peristalsis also limits
the visual field and causes failure to catch significant
lesions or grossly distorts the perceived dimensions of
polyps [24].
The Pill Cam Colon capsule (Given Imaging, Yo-
qneam, Israel) is the only VCE currently in use for colo-
nic investigation. In the most recent study of 56 patients,
colon capsule endoscopy (CCE) was followed by con-
ventional colonoscopy (CSPY). Polyp detection rate (per
patient) was 50% (n = 28) for CSPY and 62% (n = 35)
for CCE. For relevant polyps (> 5 mm) there was a cor-
respondence in the detection rates of both methods (p <
0.05). The mean sensitivity was 50% (p < 0.05), the
mean specificity was 76% (p < 0.05), the positive predic-
tive value (PPV) was 20% and the negative predictive
value (NPV) was 93% [25]. These results indicate the
general problem of VCE tumblin g during its tran sit in th e
colon and the need for VCE stabilization [24]. A recent
report on self-stabilizing capsule endoscopy systems
seems to overcome this issue [26].
2.6. Computed Tomographic Colonography
(Virtual Colonoscopy)
It has been suggested th at virtual colonoscopy perfor med
with a computed tomography is an accurate screening
method for the detection of colorectal neoplasia in as-
ymptomatic average-risk adults and compares favorably
with optical colonoscopy in terms of the detection of
clinically relevant lesions. In a 2003 study [27] Pickhardt
et al. suggested that the sensitivity of virtual colonoscopy
for adenomatous polyps was 93.8 percent for polyps at
least 10 mm in diameter, 93.9 percent for polyps at least
8 mm in diameter, and 88.7 percent for polyps at least 6
mm in diameter. The sensitivity of optical colonoscopy
for adenomatous polyps was 87.5 percent, 91.5 percent,
and 92.3 percent for the three sizes of polyps, respec-
tively. The specificity of virtual colonoscopy for adeno-
matous polyps was 96.0 percent for polyps at least 10
mm in diameter, 92.2 percen t for polyps at least 8 mm in
Copyright © 2013 SciRes. ENG
diameter, and 79.6 percent for polyps at least 6 mm in
3. Utilization of the Pseudobezoar as a
Diagnostic Screening Device
Recently proposed pseudobezoartechnology has been
suggested for the treatment of obesity and for controlled
drug delivery in the body (see e.g. [1]). Here we suggest
to utilize these retaining devices as platforms for colon
biopsy performed from the inside of the colon by a co-
lon-targeted pseudobezoar which will be in contact with
the colonic walls in a friction-like fashion severe enou gh
to collect tissue samples, but moderate enough not t o cause
excessive or abnormal bleeding or mucosal damage. This
“artificial stool” will enable generalized biopsy from the
entire organ (without actually having the information
from which exact location in the organ the tissue samples
have been collected). The advantage of having it screen
the entire organ is to overcome the miss of adenomas in
the right side of the colon as attested by Schoenfeld in
[28], who calls for improvements in colonoscopy.
A recent patent application close to what we propose
has already been filed [29]. It discloses a colon-targeting
ingestible device platform designed to recognize its entry
to the colon and expand in the colon, ultimately aiming at
improved imaging of the colon walls. On approaching
the external anal sphin cter muscle, the ingestible p ill may
contract or deform, for elimination. Colon recognition
may be based on a structural image, based on the differ-
ences in diameters between the small intestine and the
colon, and particularly, based on the semilunar fold
structure, which is unique to the colon. Additionally or
alternatively, colon recognition may be based on a func-
tional image, based on the generally inflammatory state
of the vermiform appendix. Addition ally or alternatively,
pH, flora, enzymes and/or chemical analyses may be
used to recognize the colon. The imaging of the colon
walls may be functional, by nuclear-radiatio n imaging of
radionuclide-labeled antibodies, or by optical-fluores-
cence-spectroscopy imaging of fluorescence-labeled an-
tibodies. Additionally or alternatively, it may be struc-
tural, for example, by visual, ultrasound or MRI means.
Due to the proximity to the colon walls, the imaging is
claimed to be advantageous to colonoscopy or virtual
colonoscopy, as it is designed to distinguish malignant
from benign tumors and detect tumors even at their in-
cipient stage. Various sensors are envisioned to be em-
bedded within the expandable colonic structure, includ-
ing e.g. radioactive-emission detectors, fluorescence de-
tectors, ultrasound detectors, MRI detectors, still and
video cameras operating in the visible and/or infrared
light ranges, temperature detectors, and impedance de-
Recently offered patent pending technology [30], also
offers a colon-targeting expandable structure, but it has 4
distinct features: 1)Its expansion is facilitated by a per-
meable, mesh-like gauze structure which is in constant
contact with the walls of the colon; 2) The expansion is
provided by swellable granules of an appropriate bio-
compatible polymer (e.g. polyacrylic acid) which swell
individually but do not fuse into each other, thus not
forming a uniform mass non-permeable to gases and liq-
uids causing colonic obstruction; 3) The design of the
entire device is such that the mesh-like gauze structure
can exert relatively constant pressure on the colonic
walls from the moment it reaches its final dimensions,
until it exits the organ, thus enabling abrasive contact
(for scraping maximally well the colonic walls while
retaining the scraped material within the structure, with-
out, however, damaging the colonic walls); 4) This tech-
nology aims at collecting samples of tissue and bodily
fluids, to be expelled from the body and analyzed later,
rather than detecting colon pathologies in situ via detec-
tors as disclosed in the cited US Patent Application
20050266074 [29];
The aim of the technology is creating a controllable,
organ-targeting gastrointestinal pseudobezoar with the
purpose to scrape the organ from inside in order to col-
lect maximal diagnostic information for further process-
ing. The implement can be self-administrable (in the case
of humans) or administrable autonomously or unaided,
meaning the implement is administrable in a non-inva-
sive fashion, without the need of any external positioning
or manipulating device functionally attached to it, such
as an endoscope.
When the container has the first dimension, the im-
plement can be retained in a capsule capable of being
easily swallowed or administered autonomously. Once
the capsule has dissolved and the container is released in
the colon, the colonic fluids will enter the fluid-perme-
able, mesh-like, expandable container. When the fluid
contacts the at least one swellable molecule cluster, the
cluster will swell and the container will expand to the
second dimension. When the container has expanded to
the second dimension, it is sufficiently large so as to
touch the colonic walls. The number of swellable mole-
cule clusters in the container, their individual diameter,
and their liquid-retaining and absorbing properties under
various pressures, as well as the design of the container
itself are made such that the swollen implement has an
appropriate compliance to remain in constant touch with
the colonic walls regardless of the lumen of the organ.
For example, in a section of the colon where the lumen is
large, the implement expands in a spherical shape to
touch the walls of the organ. When the lumen of the co-
lon is reduced, the implement elongates itself longitudi-
nally in the organ, but it remains in contact with the
colonic walls.
Copyright © 2013 SciRes. ENG
An initial implementation of such a p seudobezoar was
administered inchronic dogs. Two dogs had been given 6
pills per day for a month. Figure 1 depicts the pseudo-
bezoar as it has left the colon. No intestinal obstructions
have been reported during the entire duration of the tests.
Further tests need to be carried to prove safety, but the
initial testing had proven encouraging and we intend to
continue to a second stage of chronic animal testing to
demonstrate safety on a larger experimental sample.
Prospects include having this technology be competitive
with current preferred screening technology of choice,
which is assessed in [31] to be FOBT.
A recent debate was presented as to whethercolono-
scopy is still the preferred screening method for colon
cancer [28]. Indeed it seems that both physicians agree
that that is the case for now. However it would be inter-
esting to quote Dr. Schoenfield, “The “preferred” test for
colorectal cancer (CRC) is not colonoscopy… in the fu-
ture” [28].
4. Additional Prospects and Conclusion
We envision the utilization of the pseudobezoar technol-
ogy for therapy as well. Fecal transplants are new ther-
apy methods that are gaining more popularity although
they involve the administration of feces from healthy
subjects to the colons of patients suffering from a variety
of disorders, such as infection with Clostridum Difficile
bacteria [32]. The techniques used for administering such
fecal transplants are invasive, and therefore, uncomfort-
able for patients. The futuristic prospect is to use the
pseudobezoar platform for administering fecal trans-
plants in a non-invasive way, via an ingestible pseudo-
bezoar, impregnated with the bacteria to be served.
Figure 1. An image of thepseudobezoar as it has left the
colon of a dog. All dimensions are in cm.
In conclusion, a new technology which can serve as an
alternative to wide spread colon screening methods was
described. Possibilities exist for a pseudobezoar-based
medical device for colon cancer screening, early diagno-
sis of polyps, and even for bacterial transplant therapy.
We have described early results pertaining to the safety
of the implant in dogs. Efficacy over alternative screen-
ing methods and therapy is yet to be demonstrated. It
appears that the pseudobezoar technology carries great
promise both as medical diagnostic and therapeutic de-
vice and we look forward to describe new successes in
this new area of medical device development in the near
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