Use of Anorectal Manometry During Rectal Infusion of Saline to Investigate Sphincter Function in Incontinent Patients

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1 GASTROENTEROLOGY 1983;85: Use of Anorectal Manometry During Rectal Infusion of Saline to Investigate Sphincter Function in Incontinent Patients N. W. READ, W. G. HAYNES, D. C. C. BARTOLO, J. HALL, M. G. READ, T. C. DONNELLY, and A. G. JOHNSON Department of Physiology, University of Sheffield; Department of Surgery, Royal Hallamshire Hospital, Sheffield, England Anal and rectal pressures and external sphincter electromyogram were recorded continuously during rectal infusion of 1.5 L saline in 18 normal subjects and 37 patients who complained of diarrhea and fecal incontinence. All subjects exhibited a pattern of regular fluctuations in anorectal pressure and electromyogram. All except 1 of the normal subjects were able to retain 1500 ml saline without leakage, and their pressure record comprised simultaneous rectal contractions, internal sphincter relaxations, and external sphincter contractions. None of the incontinent patients were able to retain 1500 ml saline without leakages, and leakages always coincided with the peaks of rectal pressure. Two manometric patterns were observed. Fifty-nine percent of incontinent patients exhibited a pattern of contractions of similar profile occurring throughout the anorectum. This finding was associated with low basal sphincter pressures, an easily inhibited anal sphincter tone, an obtuse anorectal angle, and a funnel-shaped configuration to the anal canal. These results suggested that, in this group, the internal sphincter was weak and easily inhibited so that the whole anorectum behaved as one fluidfilled compartment recording contractions of the external sphincter. The remaining 41 % of incontinent patients exhibited a normal pattern of anorectal pressure fluctuations and had normal maximum basal pressures, although maximum squeeze pressures, rectoanal inhibitory reflex, and anorectal an- Received February 26, Accepted February 7, Address requests for reprints to: Dr. N. W. Read, Clinical Research Unit, Floor H, Royal Hallamshire Hospital, Sheffield S10 2JG, England. This study was supported by a grant from the Trent Regional Hospital Board and the Special Trustees for the Former United Sheffield Hospitals by the American Gastroenterological Association /83/$3.00 gles were abnormal. Peak rectal pressures were abnormally high in this group during saline infusion, suggesting that abnormally strong rectal contractions may play a role in the incontinence in this group. Anal sphincter function is usually assessed by manometry, carried out under resting conditions when the sphincter is not stressed in any way. Although this undoubtedly offers some insights into the way the sphincter operates, additional insight may be gained by studying the sphincter when it is being stressed in a standard manner. We have devised a method for assessing the function of the continence mechanism under stress by measuring the leakage that occurs when 1.5 L saline is infused into the rectum at a rate of 60 mllmin (1). By recording anorectal pressures and external sphincter electromyogram (EMG) during saline infusion, we have been able to investigate how the sphincter functions to retain fluid in normal volunteers (2). In the present study, we have used the same approach to determine the activity of the sphincter under stress in a group of fecally incontinent patients and to elucidate what happens during leakage of fluid. The results of this test are compared with the results of standard anorectal manometry carried out when no saline was being infused. Material and Methods Subjects Thirty-seven patients (3 men and 34 women; mean age = 58 ± 3 yr, range = yr) were referred to us because of episodes of fecal incontinence. Relevant clinical details, including factors contributing to the fecal incontinence, are given in Table 1.

2 106 READ ET AL. GASTROENTEROLOGY Vol. 85, No. 1 Table 1. Clinical Details in 37 Patients with Fecal Incontinence Obstetric Incontinence history (No. of live Bowel Duration Pelvic births and movements Associated No. Age Sex Incidence a (yr) surgery complications) per day conditions Group F LT 4-7 IBS 2 75 F T 8-9 Duodenal diverticula 3 50 F 3 b LT 6-8 IBS 4 63 F 2b 3 + 2LT < F IBS 6 43 M IBS 7 60 F lb 2 2T 8 67 F lb 4 2LT 3 IBS 9 66 F lb 5 3 L F lb F LT 3 Diverticulosis F IBS F lb Diverticulosis F Diverticulosis F 3 b L F lb 2 + 2LT F 4 2 4LT 1-8 IBS F 1 6 4L 1-2 IBS F lb F Ileocecal resection F lb LT 6 IBS F Group M 1 (N) Alcoholic cirrhosis F F 4 b 1 4LT F LT 1-3 IBS F LT 3-15 IBS colonic surgery M Vagotomy/cholecystectomy F lb 2 2 L F IBS F IBS F 2b L 1-5 Diverticulosis ~ 3 78 F lb IBS F T 1-3 IBS F Bacterial overgrowth F T F <1 (N) = Nocturnal incontinence. L = Protracted labor. T = Tear. IBS = Irritable bowel syndrome. a 1 = Incontinent every day. 2 = Incontinent at least once a week. 3 = Incontinent at least once a month. 4 = Incontinent less than once a month. b Incontinent for solids. Although many of the patients studied had obstetric or and 27 women; mean age = 53 ± 3 yr, range = yr) surgical factors that might be implicated in the etiology of were also tested. These were either healthy volunteers or their incontinence, none of them had any of the well- patients who had been admitted to the surgical wards for recognized causes of incontinence, such as generalized minor operations not involving the gastrointestinal tract. neuropathy or myopathy, or sphincter trauma. Thus, they None of these subjects suffered with diarrhea or fecal were all considered to have idiopathic fecal incontinence. incontinence or had any disease of the anal sphincter or Twenty-two patients experienced episodes of fecal in- the colon. continence only when they passed loose stools. The remaining 15 were incontinent of solid and liquid stools. Twenty-one patients complained of diarrhea, but in 20 of Ethical Considerations these, daily stool weight was within normal limits «225 All subjects and patients gave their written, ing/day) (3). All of the patients were in good mental health formed consent fof the study. The protocol was approved and well able to cooperate with the tests. by the ethical subcommittee of the Sheffield Area Health For comparison, a total of 39 normal subjects (12 men Authority (T) on January 5, 1979.

3 July 1983 DYNAMIC ASSESSMENT OF ANAL CONTINENCE 107 Study Protocol The following procedures were carried out in the same order in all the incontinent patients: measurement of maximum basal and squeeze sphincter pressures, measurement of the recto anal inhibitory reflex, measurement of rectal compliance, and the saline continence test. The total time taken to complete the tests was 2.5 hand included a rest period of 15 min between the standard manometry and the saline continence test. Radiologic measurement of the anorectal angle was carried out on a separate occasion. No bowel preparation was used for any of the tests except for offering the subjects the opportunity to empty the rectum just before performing the first test. Standard Anorectal Manometry Measurement of basal and squeeze sphincter pressures was carried out by a station pull-through technique while the patient lay on the left side (1). The anorectal probe consisted of three narrow nylon catheters (1.5 mm ad) terminating in side-opening ports situated 2.5 cm apart and orientated at 120 to each other. Each catheter was perfused with water at a rate of 1 mllmin by means of a low-compliance perfusion apparatus (Mui, PIP 2, Mississauga, Toronto, Canada). Pressure was recorded by means of a pressure transducer (Statham, 230B, Oxnard, Calif.) situated within each infusion line and connected via amplifiers to a chart recorder (Hewlett-Packard Co., Waltham, Mass.). The probe was withdrawn from the rectum in steps of 0.5 cm, remaining for at least 1 min at each station to ensure that the pressure had reached a plateau, before asking the patient to squeeze maximally. The means of the three highest basal pressures and the three highest squeeze pressures were recorded. The sphincter length was determined by noting the points at which the pressure began rising and when it returned to baseline as the catheter was withdrawn. Rectoanal inhibitory reflex was recorded by positioning the anal probe so that the middle recording channel was the muscle. The insertion was accompanied by the normal registering maximum basal pressure, and then i n f l aa t i n ~ small rectal balloon, situated 7 cm from the anal margm, with air in 10-ml increments (4). This caused a transient reflex relaxation of the internal anal sphincter. The volume of air required to completely inhibit the recovery of this reflex relaxation of the anal canal for >60 s was noted. Rectal compliance was measured by inflating a cylindrical rectal balloon with air in 50-ml increments and measuring the pressure within the balloon by means of an airfilled transducer attached to the tube (5). The pressures were corrected by subtracting the pressure in the balloon when it was inflated with the same volume in ambient air. Anorectal Manometry During Rectal Infusion of Saline Anorectal pressures and external anal sphincter (EAS) electromyography were continuously measured for at least 10 min before and for 25 min during infusion of 1.5 L of saline into the rectum at a r ate of 60 mllmin. For this purpose, a special rectal probe was constructed (2). This consisted of 4 nylon catheters bonded together. One catheter was used to infuse saline from the tip of the probe. The other three catheters were used to measure anorectal pressures. Two terminated in side opening ports, 5 cm apart (2 cm and 7 cm from the tip of the probe), and measured pressures in the anal canal and rectum. respectively. One terminated in a sleeve catheter (6.7). This consisted of a shallow groove formed by a dacron-reinforced Silas tic membrane. over which was attached a thin film of Silastic forming a narrow space. 5 cm long and open at the distal end. All the pressure-measuring catheters were perfused with water at 1 mllmin using a lowcompliance perfusion pump (Mui, PIP 2. Mississauga). Pressures were recorded by means of pressure transducers. which were situated in each infusion line and connected via amplifiers to the chart recorder. The probe was inserted digitally into the rectum so that its tip lay 10 cm from the anal margin. In this position. the side-opening ports were in the rectum and anal canal. 8 cm and 3 cm from the anal margin. respectively, and the sleeve spanned the entire anal canal. recording the highest pressure within it. Thus, although the pressure recorded by the sleeve is affected by all the muscles that make up the sphincter, we found it a useful means of recording a contraction of the EAS. which occurred over a fairly narrow high-pressure zone and may be missed using a side-opening port. The probe was fixed to the buttocks with two flexible wings orientated at 90 to its long axis. Care was taken to ensure that no movement took place during the test. If any movement occurred. the test was abandoned. and the results were not used. The electrical activity of the EAS was also measured during the test by means of a bipolar electrode (8). This consisted of two trimel-coated wires (0.025 mm). bared and hooked at their ends. which were staggered so that they did not come into contact. These were threaded through a hypodermic needle. and the whole assembly was inserted into the subcutaneous part of the EAS. The needle was then withdrawn so that the wires remained in pain associated with needle puncture but after withdrawal of the needle. the subjects could not feel the presence of the wires. Thus. maximal contraction of the EAS could take place with no attendant discomfort. The proximal ends of the wires were joined to an amplifier (DISA. Type 14A11 EMG. Copenhagen). the output of which was recorded on the chart recorder and also processed by an integrator to yield an integrated record of spike frequency and amplitude. In 1 subject. a similar method was used to assess the electrical activity of the rectus abdominis during saline infusion. Respiration was recorded throughout the test by attaching a flexible rubber tube, 4 cm in diameter. around the thorax. This was connected via a thin plastic tube to an airfilled transducer. the output of which was recorded on the chart. With the subject seated on an elevated fiberglass seat with a central aperture, 10 cm in diameter, 1.5 L of saline at 37 C was infused into the rectum at a constant rate of 60 mllmin for 25 min. Any leakage was collected by means of

4 108 READ ET AL. GASTROENTEROLOGY Vol. 85, No. 1 a funnel and cylinder arrangement under the seat, and the time that leakage occurred was marked on the patient's chart by one observer equipped with a remote marker button, continuously watching for leakage. The volume infused into the rectum before leakage first occurred and the total volume retained in the rectum were calculated. Radiologic Measurements Anorectal angle was measured radiologically. The patient lay on an x-ray couch on the left side with hips flexed to ~ 9 0 to the trunk. Fifty milliliters of a 50% solution of radiopaque barium sulfate was injected into the rectum through a narrow catheter. A plastic ball, 2 cm in diameter, attached to a beaded metal chain, was then inserted so that the ball lay in the rectal ampulla and the chain in the anal canal. In this way, the axis of the rectum was outlined by the barium, and the axis of the anal canal was indicated by the chain. A metal marker was placed on the perineal skin just behind the anal margin. Lateral radiographs were taken with the subject at rest, bearing down (strain), and contracting the sphincter maximally (squeeze). The shape of the anal canal was assessed in a total of 10 patients by taking posterior-anterior (PA) radiographs after rectal infusion of dilute barium sulfate. Analysis of Results The degree of significance between groups of data was assessed using Student's paired or unpaired t-test, whichever was appropriate. When comparing data from different groups, patients in each group were matched as closely as possible with regard to age and sex with a control group. Results Saline Continence Test Leakage of saline. None of the incontinent patients was able to retain 1500 ml of saline without leakage. The average volume retained was 850 ± 68 ml (mean ± SEM, n = 37), and the volume infused at the time that leakage first occurred was 481 ± 76 ml. In comparison, only 1 normal subject leaked saline before 1500 ml was infused. Description of Records Normal subjects. The pattern of anorectal pressure fluctuations recorded during infusion of saline into the rectum of normal subjects has been described in our previous publication (2), but to assist the reader, the results are briefly summarized below. Before the infusion started, the record in each channel was stable in 60% of normal subjects. In the remainder, the anal records described a regular pattern of oscillations, occurring at an average frequen- cy of <2/min and having an average amplitude of >25 cmh 2 0. These measurements fulfilled the characteristics for anal ultraslow waves observed by Kerremans (8) in ~ 4 of 0 normal % subjects. Shortly after the infusion began, a series of regular fluctuations in pressure became apparent in each channel in every subject (Figure 1). These comprised relaxations of the internal anal sphincter (las), which occurred at the same time as increases in rectal pressure and contractions of the EAS. Rectal pressures never exceeded anal pressures at any time during the infusion. Incontinent Patients Resting records were essentially similar to those described for normal subjects, except that sphincter pressures were lower (57 ± 5 vs. 121 ± 7 cmh 2 0, p < 0.001) and ultraslow waves were only observed in 1 patient (3%). When leakage of saline occurred, this was at the height of each rectal peak, and the rectal pressure at this time equalled or exceeded the pressure within the anal canal. Figure 2 shows that the increases in rectal pressure were not associated with contraction of the abdominal musculature. The traces recorded during rectal infusion of saline have been divided into two groups (1 and 2), depending on the pattern of anorectal contraction or relaxation. Group 1. The majority of records (59%) did not conform to the normal pattern in that there were no regular anal relaxations. Instead, the record was characterized by similar increases in pressure recorded throughout the anal canal and rectum (Figure 3). Although increases in rectal pressure could occur independently of increases in anal pressure at the beginning of the infusion, when the 2 events occurred together, they were of similar profile and occurred at exactly the same time. Moreover, both were associated with concomitant increases in the EMG of the EAS, and the integrated record showed that the electrical activity had a similar profile to the pressure fluctuations. A voluntary contraction of the EAS during saline infusion also caused similar pressure increases throughout the anorectum in group 1 incontinent patients, but not in normal subjects (Figure 4). Eleven of the 15 patients, who were incontinent to solids as well as liquids, were categorized into group 1 (Table 1). Group 2. The remainder of the patients (41 %) exhibited a pattern that more closely approximated that observed in the normal subjects (Figure 5). Regular relaxations in anal canal pressure were associated with increases in rectal pressure and external sphincter contractions. In 2 patients, the record changed from a group 2

5 July 1983 DYNAMIC ASSESSMENT OF ANAL CONTINENCE 109 A""IS_ Pre... re em H20 '] Anal Port Pre ure cmh.o '] ] R e c ~ P o r t Pressure cmh.o EMG. -..,,: I '.11 I.. II II I Integrated EMG Inluaion tlma (min) Figure 1. A typical record of anal and rectal pressure fluctuations and external sphincter electromyogram (EMG] during rectal infusion of saline in a normal subject. Note that regular increases in rectal pressure occur at the same time as anal relaxations and external sphincter contractions (seen on the anal pressure and EMG channels]. pattern to a group 1 pattern during rectal infusion. When this happened, the basal pressure fell so that relaxations in the anal port were replaced by contractions (Figure 6). Pressure Measurements Average anal and rectal pressures were determined from sequential 5-min periods of recordings obtained during rectal infusion of saline. The derivation of the pressures measured is shown in Figure 7. There were no significant differences in the anal pressures recorded during the first 5 min and the last 5 min of the infusion in incontinent patients. Thus, only those recorded during the last 5 min are expressed in Table 2. Although rectal pressures in normal subjects and incontinent patients were significantly higher at the end of the infusion compared with the beginning (p < 0.05), for the sake of clarity only those during the last 5 min of infusion are shown in Table 2. In any case, the statistical significance of the differences between the measurements from the different groups obtained during the first 5 min of infusion was the same as that from measurements obtained during the last 5 min. Anal pressures recorded by the sleeve catheter in incontinent patients were not significantly different from those em H 2 0 Anal sleeve 80] ~, ~ pressure 0 Analport 8 0 J ~ pressure 0 ~- Rectalport J ~ " ~ " " pressure Integrated EMG t - Leak j j j jj j i i i i Infusion time fminl Figure 2. A record of the fluctuations in pressure in the sigmoid colon, rectum, and anal canal (two port catheters) and fluctuations in electrical activity of the rectus abdominis in a typical incontinent patient. Note that fluctuations in rectal pressure occur independently of contractions of the abdominal wall. Figure 3. A typical record of anal and rectal pressure fluctuations and external sphincter electromyogram (EMG) during rectal infusion of saline in a group 1 incontinent patient. Identical pressure profiles are seen throughout the anorectum. These are associated with a similar profile in the integrated EMG.

6 110 READ ET AL. GASTROENTEROLOGY Vol. 85, No. 1 em H 20 Anal sleeve 320 J I, o pressure ! ~ Anal port 320J.. I J ~ pressure 0 Rectal port pressure ~ ~ ~ r a8:] t e d ~ ~ L 1 1 Cough Squeeze em H 2 0 ~ ] ~ ~ J ~ 80]. o LL... I...,., \ u.., ~ Squeeze Squeeze Figure 4. A record of the anal and rectal pressure changes observed during conscious contraction of the external anal sphincter (EAS) and a cough in a normal subject (left). compared with the changes observed in a group 1 incontinent patient during conscious contraction of the EAS (right). Note that conscious contraction of the sphincter elicits an increase in rectal pressure in the incontinent patient but not in the normal subject. recorded by the anal port. Thus, only the pressures obtained by the sleeve are given in Table 2. Basal, relaxation, and peak pressures in the anal canal were significantly lower than normal in group 1 incontinent patients, but not in group 2 patients, Basal pressures were also significantly higher in group 2 patients than in group 1 patients. Peak rectal pressures, on the other hand, were significantly higher than normal in both groups of incontinent patients (p < 0.001)' group 2 patients exhibiting significantly higher pressures than group 1 patients. Peak rectal pressures during the last 5 min of infusion were significantly higher than anal relaxation pressures in both groups of incontinent patients (p < 0,005), but not in normal subjects (Table 2), Figure 8 shows the frequency of the oscillations in em H 2 0 Anal sleeve 160J ~ group 2 patients. Mean highest squeeze pressures pressure 0 Analport o J ~ pressure ANAL CANAL Rectal port 160 0J ~ pressure em H20 Anal sleeve 160] ~ v J '... - j v ~ ~ pressure 0 I I I I Anal port 160] ~ v - v ~ ~ ~ ~ pressure 0 I I I I 8 : J ~ L Y Rectal port 160] ~ ~ ~ ' " pressure 0 I I I I I n t ~ remg a t e.\...\_,,-j d ~ l..'\\.. u.,\.,l.jj. )...).\...'v'" " }.. :, " L ' '., ~ I I I I I EMG,j, 4 j.. 5 Infusion time Iminl Figure 6. A record of anal and rectal pressure fluctuations and external sphincter electromyogram (EMG) during rectal infusion of saline in a patient whose pattern changed from group 2 to group 1 between 4 and 7 min after commencing the infusion. anorectal pressures and external sphincter electrical activity in normal subjects and incontinent patients. While the frequency of all three events in normal subjects increased throughout the study, in group 1 incontinent patients, it increased to a peak between '5 and 10 min, falling slightly to a plateau between 1.5 and 1.8 cycles/min and, in group 2 patients, it remained at a level between 1.2 and 1.5 cycles/min throughout the study. The frequency of bursts of electrical spiking activity was significantly higher in group 1 incontinent patients than normal subjects throughout the study (p < 0,05) (Figure 8). The frequency of bursts of electrical spiking activity in group 2 patients was not significantly different from normal. Results From Standard Manometry The results of standard anorectal manometry carried out under resting conditions are shown in Table 3. Mean highest basal pressures were significantly lower than in age- and sex-matched normal subjects (p < 0.01) in group 1 patients but not in EMG Integrated EMG I' Leak i I j i6 h 18 1'9 io Infusion time Iminl Figure 5. A typical record of anal and rectal pressure fluctuations and external sphincter electromyogram (EMG) during rectal infusion of saline in a group 2 incontinent patient. Increases in rectal pressure are associated with anal relaxations and low-amplitude increases in external sphincter EMG. In this patient, external sphincter contractions do not appear on the anal sleeve channel. RECTUM a Basal pressure b Peak pressure C Relaxation pressure af }L a Basal pressure b Peak pressure Figure 7. This illustrates the derivation of the anal and rectal pressures measured during rectal infusion of saline.

7 July 19B3 DYNAMIC ASSESSMENT OF ANAL CONTINENCE 111 Table 2. Anal and Rectal Pressures Recorded During Saline Infusion in Normal Subjects and in Groups 1 and 2 Incontinent Patients Normal Incontinent patients subjects Group 1 Group 2 (18) (22) (15) Age (yr) 48 :t: 5 65 :t: 2 56:t: 3 Anal canal pressures (cmh 2 O) Basal 127 :t: 12 49:t: BO 90 :t: 19 b Relaxation 52 :t: 6 30 :t: 5 44:t: 11 Peak 173 :t: :t: :t: 22 Rectal pressures (cmh 2O) Basal 34 :t: 3 39 :t: 2 36 :t: 2 Peak 50 :t: 3 68:t: 4 85 :t: 7 o. b Results are expressed as mean :t: SEM. Anal pressures are those recorded from the anal sleeve during the last 5 min. There were no Significant correlations between the age of the subject and the results of perfusion manometry in normal subjects. Results significantly different from normal. b Results significantly different from group 1 patients. were significantly lower than normal in both groups (p < 0.001). The rectal volume required to inhibit recovery of the tone of the anal sphincter during the rectoanal inhibitory reflex was significantly lower (p < 0.001) in both group 1 and group 2 patients. Rectal compliance and tone and sphincter length were not significantly abnormal in either incontinent group. Mean highest basal pressures were significantly lower in group 1 incontinent patients than in group 2, but there were no significant differences in any of the other results between the two incontinent groups. Anorectal Radiology The anorectal angle at rest, and during conscious contraction of the EAS (squeezing), was significantly more obtuse in both groups of patients 2.0 '" 1.5 's i ~ 0.5 Group I o INCONTINENT PATIENTS Group". ~. a 5 La Time from start of infusion (min) -- Analport Rectal... Electrical activity ([AS) CONTROl. o 5 La Figure 8. The average frequency of oscillations in anorectal pressure and electrical activity of the external anal sphincter (EAS) in normal subjects and in incontinent patients during sequential 5-min periods of rectal infusion of saline. compared with normal subjects (Table 3). The angle on straining was abnormally obtuse in the group 1 patients only. There were no significant radiologic differences between the two groups. Posterior-anterior films taken after infusion of barium showed that the rectum and anal canal assumed a funnel shape with a very short anal canal in 5 patients who exhibited a group 1 manometric pattern (Figure 9), while in 5 patients with a group 2 pattern, the rectum had an inverted dome shape and the canal appeared longer. Discussion Infusion of large volumes of saline into the rectum of normal subjects elicits a regular pattern of simultaneous rectal pressure increases, las relaxations, and EAS contractions, representing a repetitive series of coordinated reflex events, possibly induced by continuous rectal distention. Forty-one percent of incontinent patients showed a similar Table 3. Results of Standard Tests of Sphincter Function and Measurements of Anorectal Angles in Patients With Incontinence and Normal Subjects Normal Incontinent patients subjects Group 1 Group 2 (21) (22) (15) Age (yr) 53 ± 3 65 ± 2 56 ± 3 Station pull-through Mean highest basal pres- 83 ± 6 42 ± 4 6B ± 5 b sure (cmh 2 O) M6an highest squeeze 200 ± ± ± 16 pressurfoj (cmh 2 O) Sphincter lengths (cm) 3.3 ± :!: :!: 0.3 Rectoanal inhibitory reflex Volume in a rectal bal- 77 ± ± 7 40 ± BO loon required to completely inhibit recovery of anal tone (ml) Rectal compliance Pressure (cmh 2 0) in a rectal balloon inflated with 17 ± 2 16 ± 2 19 :!: 3 50 ml 22 ± 2 23 ± 3 24 ± ml 2B ± 3 27 ± 3 32 ± ml 31 ± 3 33 ± 6 36 ± ml 38 ± 4 40 ± 8 46 ± ml air dv/dp 13.9 :t: ± ± 2.0 (mllcmh 2 O) Anorectal angle (degrees) Rest 92 ± ± ± 5 Squeeze 90 ± ± 5" 111 ± 5" Strain 110 ± ± ± 5 Results are expressed as mean ± SEM. Results significantly different from normal values (p < 0.05). b Results significantly different from group 1 patients (p < 0.05).

8 112 READ ET AL. GASTROENTEROLOGY Vol. 85, No. 1 Figure 9. Posterior-anterior radiographs of the rectum and anal canal of a patient who exhibited a group 2 pattern during rectal infusion of saline showing a long anal canal and a rectum shaped like an inverted dome (left) and a patient who exhibited a group 1 pattern of anorectal fluctuations during saline infusion showing a funnel-shaped rectum and a short anal canal. The anal margin is marked by a small metal bead. pattern to normal subjects. The remainder, which included the majority of patients, who were incontinent to solids as well as liquids, exhibited a pattern in which the regular relaxations in the anal canal were replaced by contractions of similar profile occurring throughout the anorectum. The observation that these contractions had an identical profile to the integrated record of the external sphincter EMG suggested that they were produced for the most part by contraction of the EAS. In other words, it appeared as if the whole anorectum was behaving as one fluid-filled compartment. This interpretation was supported by the observation of simultaneous peaks in anal and rectal pressure occurring in group 1 incontinent patients when they consciously contracted their EAS, but not in group 2 or normal subjects; by the abnormally low anal tone, easily inhibited by a relatively small volume in a rectal balloon; and by the radiologic appearance of a funnel-shaped upper anal canal/rectum after infusion of barium sulfate in group 1 patients. The regular occurrence of leakage of saline at the height of the anorectal peaks can best be explained by simultaneous contractions of the rectal smooth muscle normally obscured by the contraction of the EAS and puborectalis in group 1 patients but powerful enough to force some fluid through the contracted EAS. In support of this argument, Scharli and Kiesewetter (9) observed that rectal contractions, evoked in children by infusion of fluid into the rectosigmoid, were associated with a relaxation of the las and a contraction of the EAS and puborectalis. It is important to note that the phasic activity of the EAS did not prevent incontinence in group 1 patients. On the contrary, leakage only occurred when the EAS was phasically contracted. In between phasic contractions, continence was maintained quite adequately by the tonic activity of the sphincter. The major abnormality upon saline infusion in patients with a normal anorectal pattern (group 2) was the presence of abnormally high rectal pressure peaks, which equalled or exceeded the pressure in the anal canal when leakage occurred. These high rectal pressures were not related to an abnormally increased rectal tone or reduced rectal compliance on standard manometry. Neither were they caused by contraction of the EAS, which was not visible on the rectal recordings in this group, nor by contraction of the muscles of the abdominal wall (see Figure 2) or of the puborectalis. The latter always contracts in concert with the external sphincter (8), and it is possible to record increases in rectal pressure with no concomitant external sphincter activity. Thus, it seems likely that the high rectal pressures in group 2

9 July 1983 DYNAMIC ASSESSMENT OF ANAL CONTINENCE 113 patients were produced by particularly forceful phasic contractions of rectal smooth muscle. In no incontinent patient did we find an absence of phasic external sphincter contractions during rectal distention with saline (10) or the occurrence of external sphincter contractions out of synchrony with internal sphincter relaxations. This result leads us to suspect that some of the impressive results of operant conditioning, by training patients to develop reflex transient contraction of the external sphincter in response to rectal distention (11), may not necessarily be due to the correction of an abnormal external sphincter response to rectal distention. However, this anomaly could be explained on the basis of patient selection because all of our patients had idiopathic fecal incontinence, whereas the patients responding to biofeedback conditioning had incontinence that was associated with surgical or medical conditions (11) and all were incontinent to solids. The possible importance of this study is that it records the operation of the sphincter mechanism in response to a standard fluid stress, and has demonstrated two types of incontinence, one in which the las is easily inhibited by saline infusion and the other in which the las behaves normally, but rectal pressures are abnormally high. It should, however, be pointed out that although some of our patients had incontinence to solids as well as liquids, the saline continence test monitors the response to liquids only. It may be that mechanisms other than those recorded in this study come into operation during incontinence to solids. All we can say is that the majority of our patients who reported incontinence to solids as well as liquids demonstrated a manometric profile during saline infusion that sug- gested that the whole anorectum was behaving as one fluid-filled compartment. Only 50% of patients who were incontinent to liquids but not to solids exhibited this pattern. References 1. Read NW, Harford WV, Schmulen AC, Read MG, Santa Ana CA, Fordtran JS. A clinical study of patients with fecal incontinence and diarrhea. Gastroenterology 1979;76: Haynes WG, Read NW. Anorectal activity in man during rectal infusion of saline. A dynamic assessment of the anal continence mechanism. J Physiol 1982;330: Pimparkar BD, Tulsky EG, Kaiser MH, et al. Correlation of radioactive and chemical fecal fat determinations in the malabsorption syndrome. I. Studies in normal man and in functional disorders of the gastrointestinal tract. Am J Med 1961;30: Read MG, Read NW, Haynes WG, Donnelly TC, Johnson AG. A prospective study of the effect of haemorrhoidectomy on sphincter function and faecal continence. Br J Surg 1982; 69: Read MG, Read NW, Barber DC, Duthie HL. The effects of loperamide on anal sphincter function in patients complaining of chronic diarrhea with fecal incontinence and urgency. Dig Dis Sci 1982;27: Dent J. A new technique for continuous sphincter pressure measurement. Gastroenterology 1976;71: Wheatley IC, Hardy KJ, Dent J. Anal pressure studies in spinal patients. Gut 1977;18: Kerremans R. Morphological and physiological aspects of anal continence and defaecation. Brussels: Arsica SA, Scharli AF, Kiesewetter WB. Defecation and continence; some new concepts. Dis Colon Rectum 1970;13: Alva J, Mendeloff AI, Shuster MM. Reflex and electromyographic abnormalities associated with fecal incontinence. Gastroenterology 1967;53: Cerulli MA, Nikoomanesh p, Schuster MM. Progress in biofeedback conditioning for fecal incontinence. Gastroenterology 1979;76:742-6.