Air-filled microballoon manometry for use in anorectal physiology

The physiological evaluation of operative repair for incontinence and prolapse

Women with incontinence were divided into 30 with anorectal incontinence and 63 with complete rectal prolapse. The former group comprised 14 with a sphincter disruption and the remainder with intact sphincters. After anterior sphincter repair 70% were restored to acceptable continence. Success was associated with a rise in resting and voluntary contraction pressures and improved anal sensation. Patients with prolapse underwent either anterior and posterior rectopexy, or resection rectopexy. Continence was improved in both groups. Postoperatively, 90% following resection rectopexy and 80% following anterior and posterior rectopexy were restored to acceptable continence. Postoperative defaecatory straining and incomplete evacuation were reduced, with no significant differences between the two procedures. Restoration of continence was not associated with any change in sphincter pressures. However, rectal sensory threshold and anal sensation were both improved.

Fecal incontinence

Fecal incontinence is common and socially disabling. Only a few patients with fecal incontinence present to medical practitioners. Investigative techniques have improved, and it is possible now to define accurately functional or anatomic deficits. Careful planning of treatment with the possibility of using a variety of treatment modalities is essential. Novel conservative and surgical techniques have the potential to improve the outcome for patients with fecal incontinence.

Comparing methods of measurements

1. The purpose of comparing two methods of measurement of a continuous biological variable is to uncover systematic differences not to point to similarities. 2. There are two potential sources of systematic disagreement between methods of measurement: fixed and proportional bias. 3. Fixed bias means that one method gives values that are higher (or lower) than those from the other by a constant amount. Proportional bias means that one method gives values that are higher (or lower) than those from the other by an amount that is proportional to the level of the measured variable. 4. It must be assumed that measurements made by either method are attended by random error: in making measurements and from biological variation. 5. Investigators often use the Pearson product-moment correlation coefficient (r) to compare methods of measurement. This cannot detect systematic biases, only random error. 6. Investigators sometimes use least squares (Model I) regression analysis to calibrate one method of measurement against another. In this technique, the sum of the squares of the vertical deviations of y values from the line is minimized. This approach is invalid, because both y and x values are attended by random error. 7. Model II regression analysis caters for cases in which random error is attached to both dependent and independent variables. Comparing methods of measurement is just such a case. 8. Least products regression is the reviewer's preferred technique for analysing the Model II case. In this, the sum of the products of the vertical and horizontal deviations of the x,y values from the line is minimized. 9. Least products regression analysis is suitable for calibrating one method against another. It is also a sensitive technique for detecting and distinguishing fixed and proportional bias between methods. 10. An alternative approach is to examine the differences between methods in order to detect bias. This has been recommended to clinical scientists and has been adopted by many. 11. It is the reviewer's opinion that the least products regression technique is to be preferred to that of examining differences, because the former distinguishes between fixed and proportional bias, whereas the latter does not.

Urge incontinence of faeces is a marker of severe external anal sphincter dysfunction

A proportion of patients with faecal incontinence experience debilitating urgency of defaecation and urge incontinence. This study prospectively assessed 56 faecally incontinent patients by means of standard interview, physical examination and anorectal physiology. Patients with urge incontinence, when compared with those without urge incontinence, were symptomatically worse, had had more vaginal deliveries and had more bowel actions each day. Physiological tests included anal manometry, anal electrosensitivity, pudendal nerve terminal motor latency and a standard proctometrogram. The only physiological differences between the groups were a reduction in voluntary squeeze pressure (median (interquartile range (i.q.r.)) 43 (26-67) versus 67 (45-122) mmHg, P = 0.01) and a smaller percentage change in pressure-volume, an integral of sphincter length and squeeze (median (i.q.r.) 43.5 (0-289) versus 247 (71-455), P = 0.02), in those with urgency. The authors conclude that urge incontinence is associated with impairment of the striated musculature of the anal sphincter complex.

Colonic J pouch-anal anastomosis after rectal excision for carcinoma: functional outcome

A consecutive series of 23 patients with colonic J pouch-anal anastomosis for low rectal cancer (17 men; mean age 64.4 (range 44-76) years) was studied prospectively. The mean distance from the pouch-anal anastomosis to the anal verge was 3.5 (range 2.0-4.5) cm. During follow-up one patient died from an unrelated cause and four developed metastases, two local and two hepatic. In 19 surviving patients a mean of 7 months after ileostomy closure mean bowel frequency was 2.1 (range 1-4) per day, five patients had urgency and four had mild faecal seepage up to three times per week, and seven patients had some degree of incomplete evacuation. In 13 patients there were no manometric differences before and after surgery with respect to maximum tolerated volume or maximum resting pressure, but maximum squeeze pressure was significantly lower after surgery (mean 189 versus 132 cmH2O before and after surgery respectively, P < 0.05). Colonic pouch reconstruction should be considered as an alternative to straight coloanal anastomosis in patients undergoing very low anterior resection.

Anorectal motor physiology and pathophysiology

Disorders of anorectal function are complex. A clear definition of the underlying pathophysiologic process is possible only with the use of the anal physiology laboratory. A reasonable treatment plan is then possible.

The role and technique of ambulatory anal manometry

Static anal manometry has proved itself a reliable, reproducible and objective assessment of sphincter function in the investigation of disorders of defecation and continence. Despite this, it gives only very limited information on sphincter function due to the unphysiological nature of its measurement. Technical advances, particularly in digital data storage, have made the recording of anal pressure in a normal environment for prolonged periods of time possible. This offers an improved understanding both of anal activity and the interaction of rectal and anal function in normal and pathological states. In normal subjects anal function during a number of normal physiological events such as micturition, passage of flatus and sleep have been investigated. The sampling reflex has been further defined. Abnormalities of the sampling reflex, rectal activity and slow wave activity in the anal sphincter have been demonstrated in a number of pathological conditions of the anorectum and in the states of incontinence or constipation. Effective ambulatory anal manometry remains in its infancy. With continuing advances it offers exciting possibilities in defining normal or abnormal activity of the anorectum and in the investigation of patients with disorders of defecation and continence.

Evaluation of an air-filled microballoon and mini-transducer in the clinical practice of anorectal manometry. Preliminary communication

Anorectal manometry is becoming a commonly applied investigation in the field of colon and rectal surgery. Until now, however, most of this testing was performed in specialized units, which involved considerable expense and expertise to run. The authors assessed a commercially available mini-transducer and an air-filled microballoon catheter for their applicability to clinical anorectal manometry. This system is very accurate and is proving very useful in the ambulatory setting, on hospital wards, and in the operating room. It provides a simple alternative for areas where more sophisticated manometric systems are not available.

Statistical comparison of two methods of clinical measurement

The comparison of two measurement techniques, neither of which can be regarded as being a 'gold standard', is fundamental to much basic research. This apparently simple problem raises many statistical difficulties, which are reviewed in this paper in the context of anorectal manometry. It is concluded that a recently developed approach focusing on the agreement between the two techniques is far superior to the more conventional approach based on correlation. However, until the benefits of the new analysis are more widely recognized (and it is hoped that this paper is a step towards that goal), it is argued that it is useful to present both analyses in such comparisons of measurement techniques.

Anterior sphincter plication and levatorplasty in the treatment of faecal incontinence

The surgical treatment of faecal incontinence has been traditionally divided into sphincteroplasty for sphincter disruption and postanal repair for idiopathic cases. However, many studies have failed to show a correlation between outcome and change in the anorectal angle. This study was carried out to determine the effectiveness of anterior sphincteroplasty and levatorplasty in the treatment of faecal incontinence, regardless of aetiology. Thirty consecutive patients underwent surgery, 14 with traumatic sphincter injuries and 16 with idiopathic faecal incontinence. A satisfactory clinical result was obtained in ten (71 per cent) patients in the traumatic group and in ten (62 per cent) in the idiopathic group. This was associated with a significant increase in maximum voluntary contraction pressure in the traumatic group and in those patients who had a good result in the idiopathic group (traumatic: preoperative median 80 cmH2O (range 50-115 cmH2O) versus postoperative 115 cmH2O (75-290 cmH2O), P less than 0.005; idiopathic: preoperative 105 cmH2O (45-190 cmH2O) versus postoperative 120 cmH2O (45-230 cmH2O), P less than 0.05; Wilcoxon paired signed ranks test). There was also significant improvement in anal sensation in the upper anal canal in both groups (traumatic: preoperative mean 17 mA versus postoperative 11 mA, P less than 0.05; idiopathic: preoperative 24 mA versus postoperative 9 mA, P less than 0.02). The anorectal angle increased in the idiopathic group at rest (preoperative median 105 degrees (range 86-152 degrees) versus postoperative 118 degrees (95-180 degrees), P less than 0.05). In conclusion, the type of approach (anterior or posterior) and the anorectal angle are irrelevant to the outcome of surgery for idiopathic faecal incontinence. Success appears to be related more to improved sphincter pressure and anal sensation.