JRSM >
Volume 97, Number 3 >
Pp. 111-116
Centre for Academic Surgery (Gastrointestinal Physiology Unit), Queen Mary's School of Medicine and Dentistry, Royal London Hospital, Whitechapel, London E1 1BB, UK
Correspondence to: Dr SM Scott, Gastrointestinal Physiology Unit, 3rd Floor, Alexandra Wing, Royal London Hospital, Whitechapel, London E1 1BB, UK E-mail: m.scott{at}qmul.ac.uk
 | SUMMARY |
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 TOP SUMMARY INTRODUCTIONPATIENTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Potential risk factors were identified in all but 6% of patients (7 female, 32 male). In women, the principal risk factor was childbirth (91%), and in most cases at least one vaginal delivery had met with complications such as perineal injury or the need for forceps delivery. Of the males, half had undergone anal surgery and this was the only identified risk factor in 59%. In many instances, assignment of cause was hampered by a long interval between the supposed precipitating event and the development of symptoms. Abnormalities of anorectal physiology were identified in 76% of males and 96% of females (in whom they were more commonly multiple).
These findings add to evidence that occult damage to the continence mechanism, especially through vaginal delivery and anal surgery, can result in subsequent faecal incontinence, sometimes after an interval of many years.
| INTRODUCTION |
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TOPSUMMARYINTRODUCTIONPATIENTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Patients seeking help can now be referred to specialist units for comprehensive investigations of anorectal function, in the hope that an understanding of the individual pathophysiology will allow specific rather than empirical management. The results of interventions, however, whether conservative or surgical, are commonly disappointing. Consequently, we need to identify factors in the histories of these patients that might allow preventive strategies.
Most individuals become faecally incontinent as a result of some form of insult—for example, obstetric trauma, anal surgery, neurological disease, pelvic surgery.2,8–13 In some cases, the cause–effect relation is clear, in that a temporal relation is evident, the sufferer ascribes onset of symptoms to the event (e.g. 5–13% incidence of faecal incontinence after vaginal delivery in primiparous women14,15), and the pathophysiology is demonstrable on anorectal function testing.15 Symptoms, however, may not develop until many years after the event,16 and the relation between cause and effect may then be unclear. It is known that the incidence of occult anal sphincter damage following vaginal delivery (even those deemed `uneventful') is much higher than the incidence of immediate post-partum incontinence,17 and that unsuspected anal sphincter defects occur following various `minor' anal surgical procedures.9 Such pathophysiology provides the potential for subsequent development of incontinence in combination with other factors such as ageing.18 Unfortunately, there have been no large and long-term prospective studies addressing eventual functional outcome. By performing a retrospective analysis of a large series of patients referred consecutively for investigation of faecal incontinence, we aimed to determine: the relative importance of individual proposed risk factors; the proportions of patients in whom the cause–effect relation was clear or unclear; and, in those patients where the cause–effect relationship was unclear, whether an anorectal physiology was demonstrably abnormal.
| PATIENTS AND METHODS |
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TOPSUMMARYINTRODUCTIONPATIENTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Measurements of anal pressures, rectal sensitivity, pudendal nerve terminal motor latencies, and anal sphincter integrity, with comparison with our normal ranges for each, as previously described,21,22 allowed physiological findings to be classified as anatomical22 (e.g. internal or external anal sphincter disruption), neurological (predominantly pudendal nerve motor dysfunction),22,23 due to a sensory disturbance of the anorectum,21,24 or a combination of these. Incontinence in the absence of any abnormal results was classified as idiopathic.
Statistical analysis
Data were expressed for grouped results as median and range. Fisher's exact
test was used to analyse contingency tables (Prism 3.02; Graph Pad Software
Inc., San Diego, California, USA). A P value of <0.05 was taken as
significant.
| RESULTS |
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TOPSUMMARYINTRODUCTIONPATIENTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Clinical history
Past clinical events of potential relevance had been recorded in 590
patients (94%) (Table 1). Only
7 females (1%) but 32 males (21%) had histories that contained no volunteered
potential risk factor.
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The overwhelming risk factor in females was childbirth (91%), with at least one vaginal delivery reported as complicated in 338 (78%). Complications relating to delivery included: perineal trauma (episiotomy/tear) in 259, the use of forceps in 107, and Ventouse extraction in 12. In 290 of these 338 parous females (86%), the complication occurred during the first delivery.
58% of females had also undergone pelvic surgery, most commonly hysterectomy (153), and 90 (19%) had undergone anal surgery. The frequency of multiple risk factors in females (reflecting the high prevalence of childbirth) was higher than in males (67% versus 30%). A single risk factor was present in 49% of males and 32% of females (Figure 3).
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Among the 150 females in whom a single risk factor was present, obstetric factors (complicated vaginal deliveries in 105, uncomplicated in 16) were reported in 124 (82%). 28 females had delivered a single child. The frequencies of anal surgery, abdomino-pelvic surgery and neurological factors as isolated risk factors between the other 26 (nulliparous) females were similar.
The most commonly reported risk factor in males was anal surgery (50%). In the two sexes, the incidence of anal surgical procedures was almost identical (see Table 1), with haemorrhoidectomy the most frequent procedure reported, followed by fistula surgery and sphincterotomy for anal fissure. 23% of males had also undergone pelvic surgery, most commonly procedures involving mobilization of the rectum, and appendicectomy.
Of the 76 males in whom a single risk factor was evident, anal surgery was reported in 45 (59%). 13 males (17%) had single risk factors other than the four of major interest, of varying types (e.g. anal assault, pelvic trauma, radiotherapy).
Cause–effect relations in those with single risk factors
Overall, 268 patients (43%) ascribed the onset of symptoms to a particular
event in their medical histories, more frequently in males than in females
(51% versus 40%). In those patients with isolated risk factors, again males
more frequently ascribed the onset of symptoms to the particular event (63%
versus 39% in females). Only 48 of the 124 females with obstetric factors as a
single risk ascribed the onset of their incontinence to this event
(Table 2). The median age of
onset of symptoms in these patients was 26 years lower than that of the 76
females in whom obstetric factors were the only risk but in whom no
association had been made with symptoms. The median time lag before onset of
symptoms in such females was 18.5 years (range 2–55 years). There was no
difference in duration of symptoms between those who ascribed their
incontinence to an obstetric event and those who had not.
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In those males in whom anal surgery was the only risk factor, and in whom no association had been made with subsequent symptoms, the delay between event and onset was 7.5 years, range 2–16. This was significantly shorter than the equivalent lag to symptom onset in females following childbirth (P=0.02).
Physiology
Overall, the results of physiological investigations were abnormal in 573
patients (91%). The finding of abnormal physiology was more frequent in
incontinent females than males (96% versus 76%; P=0.0001).
Incontinent females were found to have greater than one physiological
abnormality more frequently than males (64% versus 32%; P=0.0001)
(Figure 4). Of the 425 patients
who had a structural abnormality of the anal sphincter, females were more
likely to have external anal sphincter defects (87% versus 43%, respectively;
P<0.0001), and males internal anal sphincter defects (57% versus
11%; P<0.0001). A purely sensory cause of incontinence was
observed more frequently in males.
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Of the 432 incontinent parous women, 329 had evidence of structural damage (159 combined external/internal sphincter defects, 139 external sphincter alone, 31 internal sphincter alone). Of the remaining 98 parous females, 79 had resting or squeeze pressures below the normal range (74 reduced squeeze pressure alone, 25 reduced resting pressure alone), 76 showed evidence of neurogenic injury with or without rectal sensory disturbance, and 8 showed isolated sensory disturbance of the rectum. Of the 124 women in whom childbirth was the only risk factor identified from the clinical history, 95 (77%) had ultrasonographic evidence of sphincter disruption, 24 had a neurogenic and/or sensory abnormality, and the remaining 5 had reduced squeeze or resting pressures on manometry. 6 of the 7 females and 18 of the 32 males with no risk factor for incontinence identified in their histories had demonstrably abnormal anorectal physiology, most commonly solitary abnormalities.
| DISCUSSION |
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TOPSUMMARYINTRODUCTIONPATIENTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Are these results likely to represent faecal incontinence in the general population? The substantial number of young and middle-aged patients, with an age peak in the fifth decade, may reflect referral patterns. Referrals to the Gastrointestinal Physiology Unit are from secondary rather than primary sources, and the unit is part of a surgical department. It may be, therefore, that some (especially elderly) patients are not referred on the assumption that they would not be candidates for surgical interventions. The reason for the female predominance, in contrast to findings in some population studies,2,25 may be that there is a true gender difference in incidence, or that males with symptoms do not seek help, or that males are not referred for specialist investigation. The advantage of this study design over questionnaire-based investigations2,26 is that the association between event and symptoms is explored further by investigation of anorectal physiology; but a disadvantage, in contrast to prospective studies, is that the attribution of symptoms and demonstrable pathophysiology have to be assumed to relate to the volunteered event.
Major risk factors in females
Vaginal childbirth can impair the continence mechanism in several
ways,8,10,15,16,27
reflecting the combined symptoms (urge and passive faecal incontinence) and
multiple pathophysiological abnormalities observed in the majority of parous
females in this study. Although most of the parous women had experienced a
complicated delivery, it is important to note that symptoms may develop after
apparently uncomplicated
parturition.16,17
Of those females with a single risk factor in their histories, nearly 40% ascribed their symptoms to childbirth. Of those who did not ascribe incontinence to delivery, there was a median delay of 18.5 years to onset of symptoms. Pathophysiological abnormalities were evident in all but 4% of these 124 females. This study supports the findings of Sultan et al., who demonstrated prospectively an incidence of 30% occult anal sphincter defects in women immediately after their first delivery and only a 4% rise in incidence of sphincter disruption consequent upon subsequent deliveries.15,17 Long-term clinical and physiological follow-up of childbearing women is unfortunately lacking,27,28 but the results of this study are highly suggestive that covert damage to the continence mechanism does eventually become clinically overt in a proportion, perhaps several decades later, when the aetiology is more likely to be multifactorial.27
This study has also demonstrated the relative importance of anal surgery as a risk factor to continence in females,9 proctological intervention being the commonest cause in those who had not borne children vaginally and those who had had clinically uncomplicated deliveries.
Major risk factors in males
In incontinent males, usually a single risk factor was volunteered, the
commonest being anal surgery. In such procedures it is primarily the internal
(rather than external) anal sphincter that is susceptible to disruption,
either deliberately (e.g. lateral sphincterotomy) or as a complication (e.g.
haemorrhoidectomy).9
This is consistent with the predominance of passive faecal incontinence in
association with isolated internal anal sphincter defects observed in the
majority of males.
It must be stressed that, in contrast to females, one-fifth of the males had volunteered no risk factor, and that in nearly one-quarter no abnormality was observed on physiological testing. An apparent lack of risk factors may be due to inadequate history taking (for example, they were not asked about the practice of anoreceptive intercourse29 or a history of abuse in childhood, although 8 males with no history of anal surgery had internal sphincter defects). Similarly, physiological testing may not have been sufficiently comprehensive: the complex mechanics of continence involve also colonic transit and rectal evacuation,30 which was not measured.
Other considerations
The association between neurological disorders (thoraco-lumbar spinal
trauma or surgery, diabetes mellitus, etc.) and disturbed continence is well
documented.10,13,31,32
No prospective studies have been conducted on the long-term effects of pelvic
surgery, especially hysterectomy, on faecal continence; however, studies of
such interventions on urinary
function,33 the
recent identification of autonomic nerves in the supporting ligaments of the
uterus34 and the
results of the present study, lend weight to the possibility that pelvic
interventions are causally associated with faecal incontinence.
Clinical implications for the promotion of continence
The degree of individual suffering rendered by symptoms and the inability
of current practice to restore to the patient completely normal function mean
that, in obstetric, gynaecological and colorectal practice, full consideration
must be given to avoidance of those interventions known to be potentially
injurious. At present, for example, both obstetricians and pelvic surgeons may
underrate the risks of certain procedures because faecal incontinence, when it
develops, tends to be dealt with by gastroenterologists and proctological
surgeons. The excess incidence of incontinence after obstetric interventions,
especially forceps delivery, should not be used to justify an increase in the
use of caesarean
section;35
nevertheless, obstetricians should consider the risks of sphincter damage when
advising patients. Furthermore, the general surgeons who contemplate doing a
haemorrhoidectomy or other supposedly `minor' procedure should consider
whether the patient might better be referred to a specialist.
| Acknowledgments |
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| REFERENCES |
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TOPSUMMARYINTRODUCTIONPATIENTS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Female; 
male