Viscous Fluid Retention: A New Method for Evaluating Anorectal Function

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1 Viscous Fluid Retention: A New Method for Evaluating Anorectal Function Michael Srensen, M.D., Tine Tetzschner, M.D., le 0. Rasmussen, M.D., John Christiansen, M.D. From the Department of Surgery D, Glostrup Hospital, University of Copenhagen, Copenhagen, Denmark The ability to retain viscous fluid in the standing position was tested in 22 patients with fecal incontinence, 11 patients with constipation, and 26 control subjects. Viscous fluid was introduced into the rectum in increments of 50 ml. The examination was stopped when the patient complained of discomfort or the viscous fluid leaked. Eighteen of 22 patients with fecal incontinence leaked fluid, while none of the control subjects and only four of the constipated patients did so. Patients with fecal incontinence retained significantly less viscous fluid than did control subjects, whereas no difference was found between patients with constipation and control subjects. Rectal sensation from distention with air was tested in the patients as well as in the control group. The following volumes and pressures at each sensation were measured: 1) earliest defecation urge (EDU), 2) constant defecation urge (CDU), and 3) maximum tolerable volume (MTV). Patients with fecal incontinence had lower volumes than control subjects at all sensations, while patients with constipation had higher volumes at earliest defecation urge and at constant defecation urge. Rectal compliance was higher in patients with fecal incontinence than in control subjects, whereas patients with constipation did not differ from control subjects. Regression analysis showed a linear relationship between viscous fluid retention and the maximum tolerable volume and also between viscous fluid retention and rectal compliance. No difference in the ability to retain viscous fluid between male and female control subjects was found; regression analysis of viscous fluid retention in relation to age revealed decreasing volumes with increasing age. Day-to-day variation of the ability to retain viscous fluid was tested in eight persons, and reproducibility was found to be good. [Key words: Rectal compliance; Rectal pathophysiology; Viscous fluid retention] Srensen M, Tetzschner T, Rasmussen ~5, Christiansen J. Viscous fluid retention: a new method for evaluating anorectal function. Dis Colon Rectum 1992;35: A norectal function in patients with fecal incontinence is usually evaluated by anal manometry and rectal volume tolerability or rectal sensation. However, none of these parameters discriminates well between incontinent patients and No reprints are available. healthy subjects or correlates well with the clinical results of incontinence surgery. 1-4 Read et al 5 used anorectal manometry during rectal infusion of saline to monitor sphincter function in patients with fecal incontinence and found that the ability to retain 1,500 ml of saline discriminated well between incontinent patients and control subjects. In our laboratory, we have not been able to discriminate satisfactorily between continent and incontinent subjects with this method. With the aim of finding a simple way to quantitare anal continence, we studied the ability of incontinent patients, patients with constipation, and healthy control subjects to retain a viscous fluid mimicking soft feces in the standing position. The examination can be performed as a bedside procedure in less than 10 minutes. MATERIALS AND METHDS Twenty-two patients (15 women and 7 men) had incontinence to solid feces; their median age was 64 years (range, years). Twenty patients had idiopathic fecal incontinence (three of these patients also had prolapse of rectal mucosa), and two patients had fecal incontinence because of trauma (incision of anal abscess and lesion of the anal sphincters in a traffic accident). Also, 11 patients (eight women and three men) with constipation participated in the study; their median age was 45 years range, years). For comparison, 26 healthy volunteers (14 women and 12 men) with no history of anorectal dysfunction were studied; their median age was 51 years (range, years). Anal Manometry Investigations were performed with the subject in the left lateral position with knees and hips 357

2 358 S~RENSEN ET AL Dis Colon Rectum, April 1992 flexed. Maximum resting and maximum squeeze pressures were measured with a low-compliance, open-ended, perfused, polyvinyl catheter connected to a strain gauge and displayed on a chart recorder. Details of this technique have been described previously. 6 Rectal Compliance A latex balloon measuring 5 x 3 cm when deflated was placed in the rectum with the center of the balloon 10 cm from the anal verge7 The pressure probe was placed between the balloon and the rectal wall with the end of the probe situated at the middle of the balloon. The rectal balloon was distended by continuous inflation with air at a rate of 75 ml/min. The subjects were instructed to report when they experienced 1) earliest defecation urge (EDU), 2) constant defecation urge (CDU), and 3) the maximum tolerable volume (MTV) which resulted in discomfort or painful urge to defecate, The rectal volumes and pressures were recorded at each sensation. Viscous Fluid Retention The examination was performed with the patient in the left lateral position as described above. The viscous fluid, which consisted of 10 percent methylcellulose, was heated for 45 minutes in a waterbath (37 ~ Through a rectal tube, the viscous fluid was introduced into the rectum with a syringe in increments of 50 ml (Fig. 1). After each 50 ml, the tube was removed, and it was noted if leakage occurred with the subject standing. A volume of 0 ml was noted if the patient leaked the viscous fluid immediately after the first 50 ml was introduced; a volume of 50 ml was noted if leakage occurred after 100 ml was introduced, etc. The examination was stopped when leakage occurred or when the patient complained of discomfort or painful urge to defecate. Viscosity of the viscous fluid was tested in four separate samples on an MRV 8 measuring system (Viscometers, Ltd.; London, United Kingdom), using a spindle-size TR 10 at 10 rpm in a small sample adapter. Mean viscosity at 37 ~ was 41.6 X 10 centipoieses (cp); the range was 38.9 x 103 cp to 43.6 x 103 cp. For comparison, viscosity at 20~ of water and glycerol is 1 cp and 103 cp, respectively. The examination was repeated on another day in eight control subiects to evaluate day-to-day variation. RESULTS The ability to retain viscous fluid is shown in Table 1. Patients with fecal incontinence retained less than control subjects, 150 ml (0-375 ml) vs. 375 ml ( ml) (P< 0.01), while no differ- Figure 1. The necessary equipment for testing the ability to retain viscous fluid.

3 Vol. 35, No. 4 RECTAL FLUID RETENTIN AND ANAL CNTINENCE 359 Table 1. Viscous Fluid Retention, Rectal Volumes, Rectal Pressures, Rectal Compliance, and Anal Manometry in Control Subjects and Patients with Fecal Incontinence and Constipation Viscous fluid retention (ml) Rectal volumes (ml) EDU 97 (45-272) CDU 165 (89-320) MTV 230 ( ) Rectal pressures (mm Hg) EDU 6.5 (0-22.0) CDU 11.0 (0-24.0) MTV 14.0 ( ) Rectal compliance (dv/dp) (ml/mm Hg) 16.8 ( ) Anal manometry (mm Hg) Resting 90 (43-165) Squeeze 193 (89-435) Normals Fecal Incontinence Constipation 375 ( ) 150 (0-375)* 400 (50-450)(NS) 58 (30-195)* 130 (90-325)1" 93 (49-340)* 265 ( )1" 140 (75-500)* 300 ( )(P = 0.11) 4.0 (0-14.7)(NS) 6.0 (0-14.0)(NS) 6.0 ( ) (NS) 10.0 (0-33.8) (NS) 12.0 (0-47.0) (NS) 12.0 ( ) (NS) 10.2 ( )* 17.6 ( )(NS) 43 (10-109)* 65 (37-129)1 79 (22-195)* 147 (73-279) (NS) * P < 0.01 (Mann-Whitney U test), patients with fecal incontinence compared with control subjects. 1- P < 0.05 (Mann-Whitney U test), patients with constipation compared with control subjects. EDU = earliest defecation urge; CDU = constant defecation urge; MTV = maximum tolerable volume; NS = not significant. ence between control subjects and patients with constipation was found. Leakage of viscous fluid occurred in 18 of 22 patients with fecal incontinence; 17 had idiopathic fecal incontinence, and one had traumatic incontinence (Fig. 2). The results of viscous fluid retention and anal manometry in the four patients with incontinence who did not leak revealed viscous fluid retention _>200 ml (Fig. 2) and anal resting and squeeze pressures all within the normal range. Two of these patients were incontinent because of prolapse of rectal mucosa. Nine of the 18 patients who leaked had low anal pressures. Leakage occurred in only 4 of 11 patients with constipation and in none of the control subjects. Rectal sensation from distention with air was lower in patients with fecal incontinence than in control subjects at all three sensations, while patients with constipation bad decreased sensation, although it was statistically significant only at EDU and CDU. No differences in rectal pressures between control subjects and patients were found. The results of rectal sensation and anal manometry are shown in Table 1. A linear relationship between viscous fluid retention and MTV (Fig. 2), as well as rectal compliance (Fig. 3), in patients and control subjects was found (P< o.o5). No sex differences in viscous fluid retention were found in normal subjects; however, by plotting the volumes of viscous fluid retained against ' Maximum tolerable volume '(ml) 9 e a o 0 o 9 o 9 o Viscous fluid retention (ml) Figure 2. Regression of maximum tolerable volume on viscous fluid retention with 95 percent confidence intervals for prediction in patients with fecal incontinence that leaked viscous fluid (), patients with fecal incontinence that did not reak viscous fluid (), patients with constipation (&), and control subjects (). the age of the subjects, regression analysis revealed decreasing volumes with increasing age (P< 0.05) (Fig. 4). A correlation plot of day-to-day variation of the viscous fluid retention and a plot of the difference between two measurements against the mean of two measurements were performed as recommended by Bland and Airman 8 (Fig. 5). No systematic trends were found.!

4 360 S~RENSEN ET AL Dis Colon Rectum, April Rectal compliance ml/mmhg..2-" I I I I Viscous fluid retention (ml) Figure 3. Regression of rectal compliance on viscous fluid retention with 95 percent confidence intervals for prediction in patients with fecal incontinence that leaked viscous fluid (), patients with fecal incontinence that did not leak viscous fluid (9 patients with constipation (A), and control subjects () Viscous fluid retention (ml) o o ~ o o o o o i = I I i Age Figure 4. Regression of viscous fluid retention on age with 95 percent confidence intervals for prediction in 26 control subjects. DISCUSSIN Testing the ability to retain viscous fluid is an easy and reliable method for examination of anal continence. However, four patients with fecal incontinence were able to retain the viscous fluid. All four patients had anal pressures within the normal range. Surgery was performed in only one patient, who had a defect in the external sphincter after previous anal surgery. In the other three patients, symptoms were so discrete that no surgical treatment was offered. The method is well reproducible and is more physiologic than is rectal infusion of saline with the subject immobilized in a chair. 5 Since the patients were examined in both the recumbent and standing positions, measuring other parameters during the examination was not possible. Not surprisingly, the method correlates well to rectal sensation (at the MTV), although the mean volumes of air were generally lower than the volumes of viscous fluid retained. The reason for this may be that the viscous fluid is distributed throughout the rectum whereas the rectal balloon is fixed in the rectal ampulla, thus giving a more pronounced stimulus to the rectal wall. The decrease in viscous fluid retention in the control subjects with increasing age is in agreement with the decrease in MTV found in older subjects9; changes in this relationship could not be demonstrated in a previous investigation. (Se~rensen M, Rasmussen 0, Tetzschner T, Christiansen J. Unpublished data.) In conclusion, we find that testing the ability to retain viscous fluid is an easy and well-reproduci- i rnl Day 2 g := 100" e ~ / E 5o- p ~5 I I I I I ml Day 1 g -5o- 9 ~ -l-.~_ ----~, SD,,,,,,~,~ ', ~ Mean difference ~L -2 SD Figure 5. Day-to-day variation in viscous fluid retention in eight control subjects. Both a correlation plot (left panel) and a "Bland and Altman" plot (right panel) were performed.

5 Vol. 35, No. 4 RECTAL FLUID RETENTIN AND ANAL CNTINENCE 361 hie method of obtaining an objective measure of anal continence. REFERENCES 1. Womack NR, Morrison JF, Williams NS. Prospective study of the effects of postanal repair in neurogenic faecal incontinence. BrJ Surg 1988;75: Felt-Bersma RJ, Janssen JJ, Klinkenberg-Knol EC, Hoitsma HW, Meuwissen SG. Soiling: anorectal function and results of treatment. Int J Colorectal Dis 1989;4: Laurberg S, Swash M, Henry MM. Effects of postanal repair on progress of neurogenic damage to pelvic floor. BrJ Surg 1990;77: Yoshioka K, Hyland G, Keighley MR. Anorectal function after abdominal rectopexi: parameters of predictive value in identifying return of continence. Br J Surg 1989;76: Read NW, Haynes WG, Bartolo DC, et al. Use of anorectal manometry during rectal infusion of saline to investigate sphincter function in incontinent patients. Gastroenterology 1983;85: Pedersen IK, Christiansen J. A study of the physiological variation in anal manometry. Br J Surg 1989; 76: Rasmussen 00, Christensen B, S~rensen M, Tetzschner T, Christiansen J. Rectal compliance in the assessment of patients with fecal incontinence. Dis Colon Rectum 1990;33: Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;1: Ihre T. Studies on anal function in continent and incontinent patients. Scand J Gastroenterol 1974 (suppl).