Impairment of defecation in young women with severe constipation

Anorectal manometry, radiology, and tests of simulated defecation were carried out in 14 severely constipated young women and 29 age-matched controls. The resting anal sphincter pressures were reduced in the patients, but the squeeze pressures, rectoanal inhibitory reflex, and rectal pressures upon balloon distention were all normal. At rest, the anorectal angle was more obtuse in the constipated group, but there was no overall increase in perineal descent in constipated patients compared with controls. The presence of a balloon in the rectum and the onset of pain were perceived in constipated patients at volumes that were not significantly different from those in normal volunteers. Constipated patients, however, required higher rectal volumes to induce the desire to defecate and to stimulate regular rectal contractions. Constipated patients also found it more difficult to pass simulated stools from the rectum than the normal controls and, unlike most normal controls, failed to inhibit their external anal sphincter on attempted defecation. These findings suggest that young women with severe constipation have great difficulty initiating the coordinated set of events that constitute a normal defecation response.     

A Comparison of Stool Characteristics from Normal and Constipated People

In people with constipation, it is not known if decreased frequency of defecation is associated with abnormalities in the weight or in the consistency of stools or if the weight or the consistency of stools correlates with the severity of various discomforts associated with bowel movements. In neither normal nor constipated subjects has the consistency of stools been carefully correlated with their relative contents of water and solids. Our aim was to gain insight into these questions. Twenty subjects with idiopathic chronic constipation and 20 age- and sex-matched control subjects were recruited by advertisement. Stools were collected for one week. After each bowel movement, the subject's perception of various discomforts associated with the bowel movement were recorded. The stools were then analyzed. The results and conclusions were as follows: (1) Stool weight per bowel movement was similar in the two groups but stool weight per week was markedly reduced in constipated subjects. (2) Reduced stool weight per week in constipated subjects was due to a nearly proportional reduction in stool water and stool solids output. (3) Using data from both groups, there was a curvilinear correlation between percent insoluble stool solids and stool hardness, as measured by a texture analyzer; hardness increased only slightly as percent insoluble solids increased between 7 and 20%, but hardness increased dramatically when percent insoluble solids exceeded 25%. (4) Only 6% of stools from constipated subjects (2 of 34) had abnormally high values for percent stool solids and physical hardness. (5) In subjects with constipation, the severity of various discomforts associated with bowel movements (such as straining) correlated poorly with the weight or the hardness of stool that was produced by the bowel movement.     

Influence of body position and stool characteristics on defecation in humans

BACKGROUND: Whether defecation is influenced by body position or stool characteristics is unclear. AIM: We investigated effects of body position, presence of stool-like sensation, and stool form on defecation patterns and manometric profiles. METHODS: Rectal and anal pressures were assessed in 25 healthy volunteers during attempted defecation either in the lying or sitting positions and with balloon-filled or empty rectum. Subjects also expelled a water-filled (50 cc) balloon or silicone-stool (FECOM) either lying or sitting and rated their stooling sensation. RESULTS: When attempting to defecate in the lying position, a dyssynergic pattern was seen in 36% of subjects with empty rectum and 24% with distended rectum. When sitting, 20% showed dyssynergia with empty rectum and 8% with distended rectum. More subjects (p < 0.05) showed dyssynergia in lying position. When lying, 60% could not expel balloon and 44% FECOM. When sitting, fewer (p < 0.05) failed to expel balloon (16%) or FECOM (4%). FECOM expulsion time was quicker (p < 0.02). Stool-like sensation was more commonly (p < 0.005) evoked by FECOM than balloon. CONCLUSIONS: In the lying position, one-third showed dyssynergia and one-half could not expel artificial stool. Whereas when sitting with distended rectum, most showed normal defecation pattern and ability to expel stool. Thus, body position, sensation of stooling and stool characteristics may each influence defecation. Defecation is best evaluated in the sitting position with artificial stool.     

Anismus in chronic constipation

Among patients complaining of constipation, a group can be defined in which there is slow whole gut transit shown by retention of radiopaque markers but a rectum and colon of normal width judged by measurements of barium enema radiographs compared with control observations. It is not known whether their symptoms are due to an abnormality of colonic motility or to a failure of the defecatory mechanism. Defecation was simulated experimentally in a group of these patients by asking them to expel a water-filled rectal balloon. The constipated patients were not able to expel the balloon, whereas normal subjects could do so. Electromyography of the striated pelvic floor muscles during attempts at expulsion of the balloon in the constipated patients showed failure of the normal inhibition of resting activity. Failure of external anal sphincter relaxation on attempted defecation may contribute to the symptoms of some patients who complain of constipation.D.M.P. was supported by a grant from the St. Mark's Research Foundation.     

Radiologic studies of rectal evacuation in adults with idiopathic constipation

A consecutive series of 58 patients with idiopathic constipation and 20 control subjects were studied by evacuation proctography and measurements were made of changes during rectal expulsion. A wide range was found in the control group. The anorectal angle, pelvic floor descent, and the presence or size of an anterior rectocele did not discriminate between the control and patient groups. Internal intussusception was rare. Among constipated patients, the only significant differences from normal were in the time taken to expel barium and the amount of barium remaining in the distal rectum. The majority of control subjects (15 of 20) evacuated most of the barium within 20 seconds whereas 45 of 58 constipated patients took a longer time. Using the area of barium on a lateral view of the rectum as a measure, 19 of 20 control subjects evacuated at least 60 percent of the barium from the distal 4 cm of the rectum compared with only 25 of 58 patients. A varying degree of defecatory impairment was thus established among many patients with constipation. The patients were subdivided into those with a normal or abnormal whole gut transit rate as an indication of colonic function, and those who did or did not need to digitally evacuate the rectum as a clinical manifestation of an anorectal disorder. No obvious differences were found between these subgroups using the parameters measured.     

Defecometry

The parameters of defecation,i.e., maximum rectal pressure increase during straining, duration of effective evacuation, and the work performed to evacuate a simulated stool, can be quantified by defecometry, a new method to evaluate the defecation act. Simultaneous anal pressure records demonstrate the nature of the sphincter activity during simulated defecation. The test was performed on 19 patients with constipation and on 14 controls. Five patients could not evacuate the simulated stool, while five others could, but more laboriously than the remaining nine patients whose defecation was comparable with the controls. Laborious defecation is characterized by longer duration and more performed work during evacuation. Every patient with difficult or ineffective evacuation had sphincter contraction during defecation, whereas this phenomenon was not observed in patients with normal defecation. Defecometry permits more adequate identification and characterization of the outlet-obstruction-type constipated patients than the simple balloon expulsion test and the analysis of sphincter activity during straining with empty rectum in lateral decubitus. Early diagnosis and treatment of patients with outlet obstruction is important to avoid late neuromuscular damage to the pelvic floor.     

Balloon expulsion from the rectum in constipation of different types.

The defaecatory mechanism using a balloon model with simultaneous measurement of intrarectal pressure has been studied in 15 control subjects with normal bowel habit and in 39 patients with chronic constipation; 31 with a normal barium enema and eight with idiopathic megarectum. Fourteen of those with a normal barium enema had prolonged whole gut transit times as measured by radio-opaque shapes. The ability of the patient to expel a rectal balloon containing 50, 100, and 150 ml of water, lying on their side in the left lateral position was tested and if unsuccessful, in the sitting position with the knees raised. All but one of the control subjects could expel balloons in the left lateral position. Only five of 17 constipated patients with normal barium enemas and transit times could expel balloons lying on their side although a further three could do so when sitting. None of 14 patients with slow transit and normal barium enemas could expel balloons in left lateral position although three could do so when sitting. Patients with megarectum could not expel balloons in either position. Levels of intrarectal pressure with straining were not significantly different between controls, who were able to expel balloons, and constipated patients with a normal barium enema, but were greater (p less than 0.01) in patients with megacolon than in control subjects. Using the balloon model a disorder of the defaecatory mechanism is present in patients with constipation of different types, but this is not because of an inability to raise intrarectal pressure.     

Physiological studies in young women with chronic constipation

Manometric, radiological and neurophysiological investigations were performed on 34 women, aged between 14 and 53, who suffered with chronic constipation refractory to treatment, and on 27 agematched normal female control subjects. The constipated patients had more difficulty in evacuating simulated stools than control subjects and 13 out of 19 patients tested obstructed defaecation by contracting the external sphincter during straining. The constipated group required a greater degree of rectal distension than control subjects to induce rectal contractions, anal relaxation and a desire to defaecate. Other modalities of rectal sensation were normal in the constipated subjects. Compared with controls, constipated patients had significantly lower anal pressures, an abnormal degree of perineal descent on straining and an obtuse anorectal angulation at rest. These results were compatible with weakness of the pelvic floor and neuropathic damage to the external sphincter. Mouth to anus transit time was abnormally prolonged in 60% of constipated patients, but was within the normal range in the remainder. Anorectal function in patients with slow transit was not significantly different from that in patients with a normal transit time. The mouth to caecum transit time of a standard meal was prolonged in constipated patients irrespective of the duration of the whole gut transit. Gastric emptying was not significantly prolonged.     

An Examination of the Reliability of Reported Stool Frequency in the Diagnosis of Idiopathic Constipation

Objectives : To investigate the reliability of reported stool frequency in the diagnosis of constipation. Methods: Our criterion for the diagnosis of idiopathic constipation was ≤3 stools per week for ≥6 months. Subjects who believed that they met this criterion were invited to participate. Daily stool frequency was recorded over a 4-wk study period, and all stools were weighed during the final week. A colon transit study and anorectal manometry were performed at the beginning and at the end of the study. Results : On review of stool diaries from 45 subjects who described chronic constipation and who completed the 4-wk study, only 22 (49%) actually satisfied our criterion for idiopathic constipation. The remaining 23 (51%) subjects, although describing constipation, had, on average, 6 stools/wk. A history of psychiatric illness was 5 times more frequent among those whose bowel symptoms correlated poorly with objective measures. Measures of difficult defecation were similar in the two groups. Mean colon transit time was significantly longer and correlated closely with stool weight only in subjects who truly were constipated (p < 0.05). Anorectal manometry was not helpful in discriminating between those who satisfied our criterion for constipation and those who did not. Conclusions : Defining constipation on the basis of a patient's reported stool frequency may prove misleading; the diagnosis of idiopathic constipation should be supported by the use of stool diaries and a colon transit study.     

Anorectal manometry in irritable bowel syndrome: differences between diarrhoea and constipation predominant subjects.

Anorectal manometry with balloon distension was performed on 28 patients with diarrhoea predominant irritable bowel syndrome, 27 patients with constipation predominant irritable bowel syndrome and 30 normal controls. In the diarrhoea predominant group balloon volumes required to perceive the sensations of gas, stool, urgency of defecation and discomfort were significantly lower than in controls or constipation predominant patients (p less than 0.001). Diarrhoea predominant patients also had a significantly lower rectal compliance than controls or constipation predominant patients (p less than 0.03) but showed no difference in motor activity induced by distension. When the constipation predominant patients were compared with controls the only significant difference that emerged was in the volume at which discomfort was perceived. No significant differences between constipated subjects and controls were found in the distension induced motor activity. Symptom severity and psychological parameters were also recorded and the diarrhoea predominant patients were found to be more anxious than those with constipation (p = 0.04). It proved possible (by comparison with the control group) to identify three abnormal rectal subtypes in patients with irritable bowel syndrome. These were a sensitive rectum (low sensation thresholds, normal or low rectal pressure), a stiff rectum (normal or low sensation thresholds, high pressure) and an insensitive rectum (high sensation thresholds, normal or high pressure) and their distribution varied considerably depending on bowel habit. Some form of rectal abnormality was identified in 75% of diarrhoea predominant patients compared with 30% of constipation predominant subjects (p = 0.002). A sensitive rectum was a particular feature of diarrhoea predominant patients being observed in 57% of patients compared with only 7% of the constipated group (p less than 0.001).     

Bowel habits in young adults not seeking health care

In order to determine bowel patterns and perceptions of diarrhea and constipation in young adults not seeking health care, we surveyed 1128 young adults about their bowel habits. The mean number of stools varied by race and sex. Whites reported more frequent stools than nonwhites (7.8 vs 6.0 stools per week, P<0.0001) and men reported more frequent stools than women (9.2 vs 6.7 stools per week, P<0.0001). Milk and coffee consumption differed by race and sex, but did not account for the differences in stool frequency. Subjects were asked to estimate the percentage of the time their stools were normal or abnormal. The median value for normal was 85% of the time; only 3.6% of subjects reported diarrhea greater than 25% of the time, and only 7.3% reported constipation greater than 25% of the time. Subjects most commonly defined constipation as straining and hard stools and diarrhea as looselwatery stools and urgency. Investigators should use race- and sex-specific norms to study individuals who have patterns which deviate from the usual. Investigators and clinicians must also consider definitions used by their subjects.Supported in part by Grant AM29934 from the National Institutes of Health. The authors thank the Department of Family Medicine and the Student Health Service of the University of North Carolina at Chapel Hill and the North Carolina Memorial Hospital Employee Relations Office for permission to administer the survey.     

Function of the striated anal sphincter during straining in control subjects and constipated patients with a radiologically normal rectum or idiopathic megacolon

The function of the striated anal sphincter during defaecation straining was recorded by manometry and electromyography (E.M.G.) in 31 constipated patients who were unable to expel a water-filled rectal balloon with effort. This group was divided on the basis of measurement of colonic diameter into those with megacolon and those with a normal sized colon. The latter group was further divided into those with normal transit and those with slow transit. The results were compared with those recorded from 15 control subjects with normal bowel function. With straining, anal pressure fell in 12 of 15 controls while in 3 it increased. In 30 of 31 constipated patients, anal pressure rose paradoxically with straining. Electromyographic recording in controls during straining demonstrated decreased activity in 5, in 4 no change and in 5 an increase in activity. In 28 of 31 constipated patients E.M.G. activity increased with straining. These results suggest that external sphincter contraction during straining occurs in some normal subjects but more frequently among patients with constipation of different types.     

Changes in colorectal function in severe idiopathic chronic constipation

Physiologic studies of colorectal and anal function were performed in 25 adult patients with severe idiopathic long-standing constipation compared with 22 age- and sex-matched normal subjects. Only patients with primary severe idiopathic constipation with no known underlying primary etiology have been studied. No significant changes were observed in the resting or squeeze anal canal pressures. There was indirect evidence that rectal sensation was grossly impaired in 17 of the constipated patients: mean values for constant sensation compared with controls being 269 +/- 21 ml and 136 +/- 10.3 ml, respectively (p less than 0.01). The mean anorectal angles during attempted defecation were significantly less in constipated patients compared with controls (p less than 0.001), and 10 patients were unable to evacuate from the rectum a balloon containing 150 ml of a weak barium suspension. Electromyography of the pelvic floor showed increased puborectalis activity on attempted defecation in 9 subjects. Although there was no significant difference in the basal sigmoid motility index between constipated patients and controls, response to intrarectal bisacodyl (5 mg) was impaired in the constipated group, being 479 +/- 22.1 and 735 +/- 24.7, respectively (p less than 0.01). Transit time was significantly delayed in the constipated patients; the percentage of markers passed by constipated patients after 5 days was 39.0 +/- 6.9 compared with 73.9 +/- 2.8 passed by controls (p less than 0.02). These results imply that there is often a motor abnormality of the pelvic floor and the colon in patients with long-standing chronic constipation.     

Anorectal function in elderly patients with fecal impaction

Manometric and other investigations were carried out in 55 elderly patients who had impacted masses of feces in the rectum upon admission to hospital and in 36 elderly age- and sex-matched control subjects. Maximum basal and maximum squeeze sphincter pressures in the patients were similar to those in the elderly controls. Most elderly patients in the impacted group and all control subjects were able to pass a 50-ml balloon from the rectum, although a lower proportion of patients, admitted with impaction, could expel a small solid sphere. In patients the rectum had to be distended with larger volumes than in controls before the presence of the rectal balloon, pain, and the desire to defecate were perceived and before rectal contractions were generated. Rectal pressures, recorded during rectal distention, were lower in the impacted group than in the control group. Finally, anal and perianal sensation was impaired in patients with fecal impaction. These findings are similar to those described in patients with low spinal cord injuries.     

Clinical evaluation of methylcellulose as a bulk laxative

We studied a bulk laxative containing methylcellulose in a group of normal subjects as well as in a group of chronically constipated individuals. The initial study in normal subjects was performed to show that the compound could increase fecal weight without significant side effects. Fifty healthy subjects were studied. Methylcellulose in daily doses of 4 g demonstrated a statistically significant increase in fecal frequency, fecal water, and fecal solids. In the second phase, we studied a group of 59 chronically constipated individuals treated with daily doses of the laxative containing either 1, 2, or 4 g of methylcellulose or 3.4 g psyllium. All of these doses resulted in statistically significant increases in stool frequency, water content, and fecal solids. There was no increase in individual stool weight from any of the laxative doses. Methylcellulose, in a daily dose as low as 1 g, is an effective laxative.     

Colonic and anorectal motility in young women with severe idiopathic constipation

Forty-four severely constipated women and 16 (8 female, 8 male) asymptomatic volunteers underwent assessment of colon function by (a) clinical examination, (b) rectosigmoid intraluminal pressure recording, (c) colonic transit utilizing radiopaque markers, (d) anorectal manometry, and (e) rectosigmoid electrical activity. Constipated patients were characterized by (a) a greater volume and pressure of rectal distention required for both sensation and sphincter relaxation, (b) diminished basal and postmorphine motility indices only in the distal rectum, (c) delayed transit, and (d) an empty rectum when severely constipated. A neural abnormality affecting afferent nerves may be present in the rectum of female patients with severe idiopathic constipation. Delivery of stool to the rectum is impaired in these patients.     

The perceived effect of various foods and beverages on stool consistency

AIM: Some people believe that chocolate and other foods or beverages may cause constipation. This study was undertaken to quantify the effect of potentially constipating foods and beverages on apparently healthy and constipated populations of German individuals. METHODS: A questionnaire asking for the effect of certain foods and beverages on stool form (perceived consistency) was answered by 200 healthy controls, 122 patients with chronic constipation, and 766 patients with irritable bowel syndrome with constipation (IBS-C). RESULTS: Patients with constipation or IBS-C reported altered stool form after food and beverage consumption more often than controls (controls 42.5% vs constipation 52.0% vs IBS-C 57.0%, P < 0.001). Controls experienced hardening of stools less often and experienced softening more often than either constipation or IBS-C patients. When patients were asked which foods or beverages caused constipation (open ended question), chocolate was most frequently mentioned, followed by white bread and bananas. The results of systematic questioning yielded chocolate (48-64% of respondents), bananas (29-48%), and black tea (14-24%) as constipating, while prunes (41-52%), coffee (14-24%), wine (8-30%), beer (14-24%), and smoking (42-70% in those who smoked) were considered stool softeners. CONCLUSION: Several foodstuffs may exert an effect on stool consistency. Chocolate, bananas and black tea are perceived to cause constipation, while prunes are perceived to soften stools in many people. Coffee, wine and beer were perceived to soften stools in a minority of people. Cigarettes are perceived to soften stools by about half of the smokers.     

Factors associated with the frequency of stool examination: effect on incidence of reported rectal bleeding

BACKGROUND: Rectal bleeding is an important presenting symptom of colorectal cancer. The presentation and investigation of patients with rectal bleeding may be delayed if people do not regularly inspect their stool or toilet paper. AIM: To determine how frequently stool or toilet paper is inspected, factors associated with the frequency of inspection, and whether this affects the reported prevalence of rectal bleeding. METHODS: A questionnaire on the frequency of stool inspection and the occurrence of various gastrointestinal symptoms and diseases was developed, validated and sent to 2149 subjects chosen from four general practice lists in south-west London. RESULTS: There was a 79% response rate. Four hundred and forty-two of 1611 subjects (27%) examined both their stool and toilet paper every time. One hundred and two (6%) never examined either. Those who always examined their stool and toilet paper were more likely to report rectal bleeding compared to those who never examined either (23% vs 4%). They were also more likely to be male, to open their bowels more than three times per day, to have watery stools, to experience urgency, and have a history of piles. CONCLUSION: Many people examine their stools and toilet paper infrequently. The possibility that this may contribute to delayed diagnosis of colorectal cancer deserves further evaluation.     

A comparison of stool fluid and stool dialysate obtained in vivo

Stool fluid has been obtained for analysis by homogenization and high speed centrifugation of fresh stool.This fluid, from two healthy individuals with soft stools has been compared with stool dialysate obtained in vivo by retrieval of swallowed dialysis bags from their stools. Stool fluid was more acid, with a higher osmolality, an increased concentration of organic anions, sugar and ammonia, and a lower bicarbonate concentration than dialysate in vivo. It is suggested that in the individuals studied, dialysate in vivo may not be in equilibrium with the stool fluid surrounding it, and may not represent a true dialysate of faecal water.     

A Novel Technique to Identify Patients with Megarectum

Purpose Traditional methods of identifying patients with persistent dilation of the rectum, or megarectum, are associated with inherent methodologic limitations. The purpose of this study was to use a barostat to establish criteria for the diagnosis of megarectum and to assess rectal diameter during isobaric (barostat) and volumetric (barium contrast) distention protocols in constipated patients with megarectum on anorectal manometry. Methods During fluoroscopic screening, rectal diameter was measured at minimum distending pressure of the rectum, achieved using a barostat. It was also measured during evacuation proctography (volumetric distention). Having established a normal range in 25 healthy volunteers, 30 constipated patients with evidence of megarectum on anorectal manometry (elevated maximum tolerable volume on latex balloon distention) were studied. A further 10 constipated patients without evidence of megarectum were studied (normal rectum). Results Megarectum was diagnosed when the rectal diameter was greater than 6.3 cm at minimum distending pressure. Rectal diameter at minimum distending pressure was increased in 20 patients (67 percent) with megarectum on anorectal manometry, but was normal in the remaining 10 patients (33 percent) and all patients with a normal rectum on anorectal manometry. Rectal diameter was increased at evacuation proctography in only 15 patients (50 percent) with evidence of megarectum on anorectal manometry. Conclusions The prevalence of megarectum is overestimated and underestimated when rectal diameter is assessed using anorectal manometry and contrast studies, respectively. Controlled (pressure-based) distention combined with fluoroscopic imaging allowed accurate identification of patients with megarectum on the basis of a rectal diameter greater than 6.3 cm at the minimum distention pressure. Measurement of rectal diameter at minimum distention pressure may be useful in those patients with an elevated maximum tolerable volume on anorectal manometry when surgery is being contemplated. Presented at the meeting of the Association of Coloproctologists of Great Britain and Ireland, Birmingham, United Kingdom, July 2004. Published in abstract form in Colorectal Dis 2004;6(Suppl 1):72. Marc A. Gladman is supported by the Frances and Augustus Newman Foundation Research Fellowship of the Royal College of Surgeons of England.