Skip to main content

Contamination Risk During Fecal Management Device Removal: An In vitro, Simulated Clinical Use Study

Empirical Studies

Contamination Risk During Fecal Management Device Removal: An In vitro, Simulated Clinical Use Study

Index: Wound Management & Prevention 2019;65(3):30–37 doi: 10.25270/wmp.2019.3.3037


Fecal management devices (FMDs) are used to drain and contain fecal matter in incontinent, often acutely or critically ill patients to protect their skin as well as the environment from contamination. However, there is potential for contamination and resultant infection at various stages of FMD use. PURPOSE: This in vitro study was conducted to compare device removal factors and subsequent splash of simulated fecal matter of 3 different designs of FMDs using a simulated rectum. METHODS: A Universal Test Machine was used to automatically measure removal forces (in newtons [N]) and tube extensions as the FMDs were pulled from the simulated rectum by the machine. Splash distance and quantity were measured using a splash-capture cylinder and image analysis software. Each device was tested 3 times. Two-sample t tests were conducted to examine statistical differences in removal forces, removal extensions, and splash areas. RESULTS: The forces required to remove the FMDs from the simulated rectum were significantly lower for the device with a collapsible, donut-shaped retention balloon compared with the devices with a green, foldable, trumpet-shaped retention cuff and a foldable, spherical-shaped retention balloon (12.0 ± 0.3 N vs. 32.6 ± 4.3 N and 34.8 ± 3.1 N, respectively; P <.05). The extensions of the catheter tubing were significantly lower for the device with a collapsible, donut-shaped retention balloon compared with the devices with a green, foldable, trumpet-shaped retention cuff and a foldable, spherical-shaped retention balloon (32.0 ± 7.5 mm vs. 81.3 ± 9.1 mm and 105.2 ± 10.6 mm, respectively; P <.05). Simulated fecal matter was splashed over mean areas of 25.5 ± 16.1 cm2 and 27.3 ± 13.5 cm2 for the devices with a green, foldable, trumpet-shaped retention cuff and a foldable, spherical-shaped retention balloon, respectively; no splash was observed for the device with a collapsible, donut-shaped retention balloon. CONCLUSION: In vitro observations suggest contamination and potential infection risk during FMD removal from the patient are influenced by FMD design. Future in vitro and clinical studies assessing the infectious nature of effluent and methods for containment are warranted.


Fecal incontinence is a major problem in the comprehensive nursing care of acutely and critically ill patients. If not managed properly, uncontained and corrosive diarrhea can lead to perianal skin breakdown and present a major contamination or infection risk to patients and the hospital environment. In a prospective study,1 33% of 152 hospitalized patients had fecal incontinence; more than twice (58% vs. 24%) as many of these patients were receiving care in the intensive care unit (ICU) compared with acute care units. 

Various containment methods for diarrhea have been used over many years, including absorbent pads, diapers, fecal collectors, and tube draining devices. However, these traditional methods are generally considered ineffective and are labor intensive for critical care nurses.1 In 2003–2004, a new class of indwelling fecal management devices (FMDs), including the Zassi Bowel Management System (Zassi Medical Evolutions, Fernandina Beach, FL) and the Flexi-Seal (F-S) Fecal Management System (ConvaTec Ltd, Reading, UK) was introduced.

Indwelling FMDs are now commonly used for patients with fecal incontinence that are hospitalized for acute illness or long-term critical care.2,3 These devices are intended to be anchored in the rectal vault via a retention mechanism such as a water-inflatable balloon or cuff. Fecal matter drains away from the patient through a catheter tube to a collection bag, diverting the potentially infectious matter away from the patient. This serves to protect the patient’s surrounding skin,4 the caregiver, and the hospital environment. Balloons/cuffs are subsequently deflated for device removal from the patient.

A clinical evaluation5 of 42 patients in acute and critical care reported FMDs are practical, caregiver- and patient-friendly, efficacious, and time efficient (for use up to 29 days). The study additionally noted FMD use may be cost effective compared with standard care (cleansing with skin protectant and use of an external fecal incontinence collector) in critical care institutions, as shown in a 59-patient randomized controlled trial6 and a budget impact analysis.7 The ability of F-S to maintain skin integrity, facilitate accurate fluid balance, reduce odor and perineal soiling, and improve personal hygiene, patient comfort, and dignity has been noted in clinical case studies among 3 patients with graft-versus-host disease8 and in 18 patients recovering from burns.9 A retrospective review10 of 50 patients who had been managed with F-S reported the device was safe and effectively contained fecal material when used appropriately and regularly checked; the authors also reported a low rate of leakage around the insertion point of the device.

In vitro simulated clinical use studies11,12 have explored the potential infection risk during FMD collection bag change. Jones et al11 described how F-S could effectively contain Clostridium difficile spores in simulated effluent over a 31-day period, including several collection bag changes, compared with standard underpads. The study demonstrated that although opening the bag during change of otherwise closed FMDs exposes the environment to potentially infectious material, risk was minimized when Good Clinical Practice (careful disconnection, closure of used bag, and avoiding spillages) was implemented during bag change. A comparative in vitro study12 subsequently reported that neither F-S, described as an “open” bag change system, nor DigniShield (DnS) Stool Management System (C.R. Bard Inc, Covington, GA), a “closed” bag change system, could contain C difficile spores or vegetative cells in canine stool over a 30-day period that involved daily bag changes.

The likelihood of shedding or splashing fecal effluent into the surrounding environment is more likely during FMD removal than at bag change, so the risk to the patient’s surrounding tissue, as well as to the caregiver and the environment, is likely to be higher during removal. The device removal procedure is harder to control because it relies on a combination of design (of the deflated balloon/cuff) and patient physiology (eg, patient size and rectal and sphincter muscular tone). Additionally, the less-accessible location of the rectum makes it more difficult to protect the hospital environment during device manipulation, than, for example, the location of the bedside collection bag. 

To the best of the authors’ knowledge, no clinical or simulated clinical use studies have investigated the potential risk for contamination during removal of the balloons/cuffs of FMDs. The purpose of the in vitro study was to assess 1) the force required to remove the deflated balloons/cuff from an anatomically appropriate model, and 2) the potential splashing of simulated fecal effluent during device removal.  

Materials and Methods

The study investigated device removal for 3 leading commercially available FMD systems — DnS, InstaFlo (IsF) Bowel Catheter System (Hollister Inc, Libertyville, IL), and F-S — using simulated clinical conditions that mimicked realistic clinical situations as closely as possible. F-S employs an opaque, donut-shaped, collapsible, silicone balloon, and IsF employs an opaque, spherical, foldable, silicone balloon; DnS has a green, trumpet-shaped, foldable, silicone cuff, all of which are inflated for retention, and deflated before removal (see Figure 1). 

A simulated rectum was made from soft rubber with a 15 mm-diameter model sphincter; internal dimensions were based on the average rectal physiologies from full-body, magnetic resonance imaging data.13 Simulated fecal effluent, based on Bristol Stool Grade14 6-7 (mushy/liquid stool), was prepared from Reinforced Clostridial Medium (LabM), 0.4% bacteriological agar (Oxoid, Basingstoke, UK), with Browning (Sarson’s, London, UK) added for color.15 

Removal force and extension. The catheter tube section of each device was trimmed to a length of 150 mm from the base of the balloon/cuff end. This enabled the samples to be accommodated in a Universal Test Machine (UTM; Zwick, Leominster, UK), a tensile test machine capable of measuring the yield or compressive strength of materials in terms of force (applied by the machine in newtons [N], the International System of Units-derived unit of force) and distance (travelled by the machine grip; mm) (see Figure 2a). For F-S and DnS, the inflation and irrigation tubing were left in place and functional, with just the main catheter trimmed off. This was not necessary for IsF because the inflation and irrigation tubes were close to the balloon end. 

The simulated rectum was clamped in a polycarbonate frame and bolted to the UTM. The rectum was filled with simulated fecal effluent via the sphincter. Using the syringe provided with each device, residual air was removed from the balloon/cuff. Six (6) mL of lubricant (KY Jelly; Reckitt Benckiser, Slough, UK) was spread evenly over the deflated balloon/cuff and 1 mL was applied around the simulated sphincter, as would be done in clinical practice. The balloon/cuff then was inserted into the sphincter as per the device instructions for use. Once correctly situated within the simulated rectal cavity and immersed in the simulated fecal effluent, the balloon/cuff was inflated with the appropriate volume of water. The balloon/cuff then was deflated as described in device instructions for use. The trimmed end of the catheter tube was subsequently clamped in the jaws of the UTM, 50 mm above the sphincter, and the UTM jaws were raised at a fixed rate of 100 mm/minute. The maximum forced required to remove the deflated balloon/cuff (in N) and the extension distance (mm) travelled by the UTM jaws were automatically measured and recorded by the UTM as an electronic and printable report; the test stopped when the balloon/cuff had been pulled fully through the sphincter. The simulated rectum, simulated fecal effluent, and device insertion, inflation, and deflation processes test was performed 3 times for each device; each device was cleaned and dried between replications. 

Splash capture. Similar to the removal force and extension study, the catheter tube section of each device was trimmed, but to a length of 430 mm from the base of the balloon/cuff end and, for F-S and DnS only, the inflation and irrigation tubing were left in place. Fabric-backed adhesive tape (AT200 Matt Gaffa; Advance Tapes, Leicester, UK) was wrapped around the catheter tubes below the insertion depth markers to support the catheter tube and to prevent the elastic-stretching effect of tube extension (see Figure 1). To capture any dispersal of simulated fecal effluent during the automated removal of the deflated balloon/cuff, the trimmed end of the catheter tube was threaded through a 16-cm outer diameter annular paper disc (standard white 80-gsm paper) with a 6 cm-diameter centralized hole, so the paper rested on top of the simulated rectum. The vertically held catheter tube was sheathed in a 35-cm tall plastic cylinder (external diameter 15.2 cm; internal diameter 14.5 cm) lined internally with A3 paper. The top of the cylinder then was covered with a second annular paper disc so the catheter tube was completely enclosed in a splash-capture cylinder (see Figure 2b). The trimmed end of the catheter tube was clamped in the jaws of the UTM where it exited the splash-capture cylinder, 350 mm above the sphincter. The UTM jaws then were raised at a fixed rate of 100 mm/minute, and the test was stopped when the balloon/cuff had been pulled fully through the sphincter. Care was taken to ensure the catheter tube did not stretch and did not touch the paper. The test was performed 3 times for each device, and each device was cleaned and dried between replications. The quantities and distances of splash were analyzed by placing dried splash-capture papers (an A3 sheet and 2 annular discs per test replication) on an A3-sized photographic light box and covering with a Perspex sheet. A tripod-mounted digital camera was placed at a fixed distance of 100 cm above the papers. Photograph exposure limits were set to obtain maximum illumination and contrast, and images of all splash-capture papers were taken. Splash areas were calculated from images (JPG files of 100 MB resolution) processed with Image Pro Analyzer software, version (Media Cybernetics, Rockville, MD) as follows:

  • The raw image was rotated until the bottom edge was horizontal/aligned to the reference grid.
  • The area of interest was cropped 1 cm inside the edge of the light box.
  • The blue channel was extracted from the red-green-blue image (for the best contrast for brown effluent against white paper; see Figure 3).
  • Brightness, contrast, and gamma were manually optimized to obtain a subjectively optimized image.
  • Intensity peak was selected in the histogram, eliminating low intensities.
  • Intensity area count was calculated and the screen data were captured.
  • The total splash area per sheet (cm2) and the relative percentage of stained area to unstained area were calculated.

Two-sample t tests were conducted using Minitab 17 software (State College, PA) to examine differences in removal forces, catheter tube extensions, and splash areas.


Removal force and extension. The mean forces required to remove the deflated balloons/cuffs of the devices are shown in Figure 4a. The force required to remove the deflated DnS cuff (32.6 ± 4.3 N) and the IsF balloon (34.8 ± 3.1 N) was significantly greater than that required to remove the deflated F-S balloon (12.0 ± 0.3 N; P <.05), but no statistically significant difference was noted between the force required to remove the DnS cuff and IsF balloon. 

The mean extensions at the maximum removal force required to remove the deflated balloons/cuffs of the devices (ie, how far the UTM grips had to move upward) were 32.0 ± 7.5 mm for F-S, 81.3 ± 9.1 mm for DnS, and 105.2 ± 10.6 mm for IsF (see Figure 4b). The extension during removal of the deflated DnS cuff and the IsF balloon was significantly greater than for the deflated F-S balloon (P <.05), and although the extension was greater for IsF balloon removal than for the DnS cuff, this difference was not statistically significant. The photographs in Figure 5 are representative images of each device immediately before the balloon/cuff breached the simulated sphincter. The strain placed on the simulated sphincters by the controlled removal of each device could be noted by the height of the sphincter protruding over the model casing. Minimal strain was exerted on the simulated sphincter in the case of F-S (see Figure 5a) compared with DnS (see Figure 5b) and IsF (see Figure 5c). The use of lubricant around each balloon/cuff before insertion and the simulated effluent in the vicinity helped negate the friction effects of rubber-on-rubber.

Splash capture. Images of each splash-capture cylinder (A3 sides) are shown in Figure 6. No visible splash of the simulated fecal effluent occurred in any of the splash-capture cylinders for F-S (see Figure 6a), but visible areas of splash were noted for all 3 splash-capture cylinders for both DnS (see Figure 6b) and IsF (see Figure 6c). For the devices where simulated fecal effluent splash was observed, the splash distribution was spread over the A3 sides of the splash-capture cylinders (see Figures 6b,c). 

Splash-capture data analysis showed no splash-capture of the simulated fecal effluent was recorded for F-S (see Table). The mean splash coverages of 25.5 ± 16.1 cm2 for DnS and 27.3 ± 13.5 cm2 for IsF were not significantly different. For both devices where splash of simulated fecal effluent was recorded on removal, the largest splash areas were recorded on the larger A3 side capture papers. However, in terms of percentage splash, most splash tended to be collected at the top of the collection cylinder (furthest away from the model sphincter), and the least amount was collected at the bottom (around the sphincter). This suggests that for DnS and IsF, the splash of simulated fecal effluent on removal from the sphincter occurred with sufficient force to splash the capture papers located furthest away from the sphincter instead of in the immediate vicinity.


Fecal effluent is highly infectious, with a review reporting bacterial loads in healthy individuals comprising 1 x 1011 to 1 x 1012 colony forming units/g and up to 500 different species.15 A variety of pathogens have been identified in fecal effluent, including multidrug-resistant C difficile, as recently reported in vitro for 10% of diarrheic samples from 136 long-term care patients.16 A review17 of European health care facilities covering the years 2000 to 2010 showed outbreaks of C difficile in hospital settings have been associated with prolonged duration of hospital stay (median stay of 124 days in the UK), increased health care costs (€5000 to €12 000 incremental cost), and increased mortality (42% in the UK). Consequently, containment of fecal effluent is essential in health care institutions to help prevent the spread of pathogenic and antibiotic-resistant microorganisms. Unlike absorbent pads, which have no containment properties, closed FMDs may help contain fecal effluent.11 However, contamination of surroundings may occur during the removal of FMDs, because fecal effluent is potentially splashed as the deflated balloon/cuff is pulled through the sphincter.

The current study compared simulated effluent splash on removal of 3 FMDs using an anatomically validated simulated rectum. To the best of the authors’ knowledge, this is the first study of its type to investigate potential environmental risk during the simulated or clinical removal of FMDs. Similar levels of simulated effluent splash were observed following removal of DnS and IsF. Most splash was detected to the side and 7 cm to 36 cm from the sphincter, but some splash also was captured more than 1 foot (35 cm) away from the sphincter. In contrast, no splash of simulated effluent was detected following removal of F-S. The potential clinical implications of these in vitro observations are that the removal of some FMD designs may result in splash of potentially infectious effluent of greater quantity and distance than other FMD designs.

Using the simulated rectum, the force required to remove the FMDs and the extension of the sphincter end of the catheter tubing also were compared. Health care providers tend to grip the catheter tube close to the sphincter in order to remove the device. Therefore, to simulate clinical removal of the devices, all test procedures included application of adhesive tape on the catheter tubes below the insertion depth markers to avoid interference of tube elasticity. Using this model, the force and associated catheter tubing extension required to remove the deflated DnS cuff and the IsF balloon were significantly greater than for the deflated F-S balloon. This may be because, although all 3 FMDs employ a silicone balloon/cuff and silicone cannula tubing, the balloon/cuff geometry and rigidity are very different. F-S incorporates a low-profile retention balloon in a donut shape, and because F-S is equipped with a finger pocket to facilitate balloon insertion into the rectum,5 the balloon end is designed to be soft and pliable. Both DnS and IsF require the cuff/balloon to be folded at a 45˚ angle to form a conical shape, which then is folded and pushed through the anal sphincter for retention in the rectal vault.18 Because of the differences in the insertion methods, the cuff/balloon of DnS and IsF are larger and necessarily stiffer. For example, the collapsed cuff/balloon end diameter is approximately 39 mm in DnS and 21 mm in IsF, compared with 15 mm in F-S. 

The size of the inflated cuff/balloon is also different among the 3 FMDs. The largest is the DnS cuff (trumpet shape, 36 mm in height and 56 mm to 57 mm in diameter when inflated with an indicated volume of 45 mL of water18), followed by the IsF balloon (spherical shape, 32 mm in height, and 56 mm to 57 mm in diameter when inflated with 40 mL of water19), and the F-S balloon (donut shape, 26 mm in height and 53 mm to 57 mm in diameter when inflated with 35 mL to 45 mL of water20).  

It is important to emphasize that the use of FMDs should always be carefully considered. FMDs are inserted into the patient’s rectum and potentially remain in situ for a prolonged period of time to manage fecal incontinence (up to 29 days; ie, the maximum for nonimplantable medical devices). Although this is a minimally invasive treatment, it has the potential to harm the patient along the usage continuum of insertion-in/use-removal. FMDs that are demonstrated (as for F-S in the present study) or claim to require less removal force should still be used with caution, because case studies21 have shown their removal can cause patient trauma.


The limitations of this study include the small sample size that may have reduced the power to detect significant differences in the splash outcomes. Because an in vitro model was used, patient comfort level on removal of the devices could not be studied. However, as patient comfort levels are known to vary considerably during the insertion of different FMDs,22 it is likely that removal force would influence patient comfort and potentially affect the risk for tissue damage or skin maceration. It was not possible to measure damage to the rectum tissue on removal of the devices using the simulated rectum. However, in patients with compromised skin conditions, as frequently observed in ICUs, the impact of removal force and the device extension on the sphincter muscle would be expected to have clinical consequences. 

Regarding the splash test findings, the direct impact on spread of infection in a clinical setting could not be ascertained from this in vitro testing. Despite the use of anatomically and physically relevant simulated rectum and effluent, the elimination of potential user bias by use of a UTM (which has not been noted in bag change studies11,12) and quantifying a difficult-to-measure effect such as effluent splash, clinical assessment of environmental contamination and infection risk during removal of FMDs would ultimately be required to validate these initial in vitro observations. A future in vitro study using simulated effluent containing C difficile to investigate the potential spread of pathogenic organisms or spores during FMD removal is recommended.


In an in vitro, simulated clinical use test, the removal of different FMDs from a simulated rectum was shown to require varying levels of force and catheter tube extensions, resulting in differing levels of splash of simulated fecal effluent, with theoretical environmental contamination and infection risk consequences. The extent of splash produced by each device upon removal from the simulated rectum was found to be related to both greater force to remove and tubing extension measured. What was noted in these in vitro observations infers potentially deleterious effects on patient tissue, less control during device removal for the user, and an increased risk of fecal splash. As such, these observations regarding the levels of fecal effluent containment offered by different FMDs should be considered by health care providers when assessing the potential risk of contamination and infection to the hospital environment, caregivers, and neighboring patients. 


Dr. Metcalf is Associate Director, Science & Technology, ConvaTec Ltd, Deeside, UK. Dr. Tsai is Director of Continence & Critical Care R&D, ConvaTec, Bridgewater, NJ. Ms. Williams is a Research Scientist, Physical Testing; Mr. Pritchard is Physical Testing Manager; Dr. Parsons is Director, Science & Technology; and Mr. Bowler is Vice President, Science & Technology, ConvaTec, Deeside, UK. 


Please address correspondence to: Daniel Metcalf, ConvaTec Ltd, GDC, First Avenue, Deeside Industrial Park, Deeside, CH5 2NU, UK; email: