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12. Innovations in the Treatment of Faecal Incontinence 261
13
Surgical Management
of Constipation
Ian G. Finlay and Andrew A. Renwick
1. Introduction
Many patients complain of constipation but few require surgery. While
symptoms may be improved when surgery is performed, injudicious inter-
vention may make symptoms worse, causing patient discontentment and,
all too frequently, litigation. Consequently, a carefully planned strategy is
required for the identification of those patients who will benefit from
surgery and for the selection of an appropriate operation. In this chapter
the authors describe the protocol used in the Department of Coloproctol-
ogy, Glasgow Royal Infirmary, for the investigation and management of
patients with severe constipation referred for a surgical opinion.
Constipation is a generic term that may imply a number of different
symptoms [1] and at the outset the clinician requires to elicit which of these
symptoms is predominant. In the first instance, it is important to determine
the duration of symptoms. Are they life-long, dating to childhood (as in
idiopathic slow-transit constipation, Hirchsprung’s disease, or megarectum)
or do they have a clear precipitating factor (postchildbirth, postpelvic
surgery, or after severe gastroenteritis)? What does the patient mean by
constipation? Is it the complete absence of the call to stool with bloating
and nausea (as in slow transit) or is it a sensation of weight and fullness in
the perineum with a sensation of incomplete evacuation (as in perineal
descent syndrome and rectal intussusception/prolapse)? Does the patient
digitally aid defaecation by supporting the posterior vaginal wall, the classic
symptom of rectocoele, or do they attempt to provide support behind the
anus, a feature of generalised weakness of the pelvic floor with perineal
descent? Finally, it is important to identify whether the most troublesome
symptom is pain. Patients who benefit most from surgery for constipation
do not report pain as a prominent symptom.The presence of severe abdom-
inal pain should raise the suspicion of underlying irritable bowel syndrome,
an absolute contraindication to surgical intervention.
When patients are referred for a surgical opinion for constipation they
have usually already had a full range of laxatives and basic investigations.
262
It is important, however, to be aware of any medications that may con-
stipate such as analgesics, psychotropics, or the use/over use of over-
the-counter medicines. All patients should have thyroid function tests and
a radiological examination of the large bowel. Every year we identify 2 or
3 patients with previously undiagnosed myxoedema in whom symptoms
resolve when thyroxine is prescribed. It should also be noted that myx-
oedema is associated with rectal prolapse/intussusception. A contrast study
is preferred to colonoscopy because in addition to excluding a carcinoma,
contrast study gives an indication of the diameter of the hindgut and allows
a major distinction to be made between patients. Individuals can be classi-
fied as having constipation with a normal caliber colon/rectum or consti-
pation with a megabowel.
A contrast study also gives an impression of the redundancy of the bowel
and may identify the presence of colonic volvulus.
2. Severe Constipation and
Normal Caliber Colon/Rectum
2.1. Investigations
Having identified that the patient has a normal diameter colon and rectum,
the two most useful and easily performed investigations are evacuation
proctography and a colonic transit study [2]. The colonic transit study cru-
cially confirms that the patient has objective evidence of severe constipa-
tion. The test does not need to be complicated and can be performed in any
hospital with X-ray facilities. Patients are given 20 inert markers (Sims
Portex®) to swallow and advised to avoid using laxatives or enemata. The
presence of 5 markers at 5 days after ingestion on a straight abdominal X-
ray indicates constipation, more than 5 markers indicates severe constipa-
tion. This is an important initial test because many patients referred with
constipation, who consider their symptoms to be severe, will have a normal
transit study. Although more complicated scintigraphic and differential
transit studies have been described and can be useful, it is not the authors’
practice to use these at this screening stage. The value and role of proctog-
raphy is more controversial and less well defined because it is less objec-
tive. It will, however, identify gross anatomical abnormalities and those
patients with obstructed defaecation or anismus who are unable to empty
even liquid from the rectum due to pelvic-floor spasm. On the basis of these
investigations there are 4 possible combinations of results (Figure 13.1) that
are used to determine the need for further investigations and the devel-
opment of a treatment plan. These are: (a) delayed transit and a normal
proctogram, (b) normal transit and an abnormal proctogram, (c) delayed
transit and an abnormal proctogram, and (d) normal transit and a normal
proctogram.
13. Surgical Management of Constipation 263
264 I.G. Finlay and A.A. Renwick
2.1.1. Delayed Colonic Transit and a Normal Proctogram
(Slow-transit Constipation)
The combination of delayed colonic transit and a normal proctogram
typically identifies those patients who have slow-transit constipation, that
is,patients who have objective evidence of delayed transit and normal evac-
uation. The symptoms may be either idiopathic or attributed to a specific
event such as childbirth, hysterectomy, or, occasionally, severe gastroen-
teritis. These 2 distinct clinical patterns probably have a different patho-
physiology although they are frequently reported together as a single entity.
Classical idiopathic slow-transit constipation (ISTC) is a disorder of young
females, in whom the symptoms are life-long, dating to childhood. Patients
with ISTC have an absence of the call to stool with symptoms of nausea
and abdominal distension. Bowel movements may be as infrequent as once
every 2–3 weeks and then only with the use of laxatives. Although these
patients may complain of abdominal discomfort (especially prior to evacu-
ation), pain is not a prominent symptom and if present should raise the
suspicion that the underlying diagnosis is one of irritable bowel syndrome.
Surgery should be avoided in patients in whom pain is the predominant
symptom because it is rarely successful [3].
The exact aetiology of idiopathic slow-transit constipation is unknown
but it may have a genetic basis because there is frequently a positive family
history [4]. Several studies have shown an abnormality of colonic motility
characterised by a reduction in the frequency, amplitude, and duration of
NORMAL CALIBRE BOWEL
Barium Enema &
Thyroid function tests
Megabowel
(see Part B)
Colonic Transit Study & Proctogram
Delayed Transit
Normal Proctogram
Idiopathic slow transit
constipation
Colectomy and Ileorectal
anastomosis
Precipitating factor
(childbirth/hysterectomy)
Delayed Transit
Abnormal Proctogram
Uncertain
Biofeedback +/-
Colostomy
None
Normal Transit
Abnormal Proctogram
Intussusception/prolapse
Rectocele
Resection rectopexy
Repair of rectocele
Anismus
(Biofeedback)
Normal Transit
Normal Proctogram
Functional bowel
disorder
None
None
Diagnosis
Surgery
Exception
Figure 13.1. Flow chart demonstrating the investigative pathway in constipated
patients.
13. Surgical Management of Constipation 265
propulsive contractions in the large bowel [5]. There is a similar abnormal-
ity in the small bowel where spontaneous mechanical activity arises from
electrical activity of lower intensity and of shorter duration [6] than in con-
trols. It has been suggested that these features may be related to a colonic
smooth-muscle myopathy that in turn leads to the inability of the surface
membrane to initiate and maintain periods of high-frequency spike
activity [5,7].
At the biochemical level, abnormalities have been identified in both nitric
oxide synthetase and vasoactive intestinal peptide-containing neurons [8,9],
which may explain the observation that there is a myenteric nerve abnor-
mality with a functional cholinergic deficit in response to electrical stimu-
lation [10,11]. Quantitative tests suggest the presence of a small-fibre
neuropathy [4]. In addition, it has recently been reported that the intersti-
tial cells of Cajal that are required for normal intestinal motility are reduced
throughout the colon and rectum [12,13], suggesting that this is an ab-
normality of the entire lower gastrointestinal tract. It may also extend to
the upper gastrointestinal tract because it has been shown that patients who
fulfil the clinical criteria given above for ISTC have evidence of delayed
gastric [14,15] and gallbladder [16] (Figure 13.2) emptying with prolonged
Figure 13.2. Cholecystokinin provacation test
demonstrating delayed gallbladder emptying.
small-bowel transit [17,18]. It is unknown, however, whether this a mani-
festation of a pan-gastrointestinal disorder or whether upper gastrointesti-
nal delay is secondary to colonic inertia because it has been shown that
inflation of a balloon in the rectum of humans and animals inhibits the
entire gastrointestinal tract [19,20]. In an attempt to answer this question,
gastric emptying has been measured before and at 1 year after total colec-
tomy and ileorectal anastomosis for ISTC [21]. Although gastric emptying
improved in the majority of patients, it returned to normal in only one half
of those studied, suggesting that the extent of the abnormality is variable
[10]. Unfortunately, the severity of the gastric-emptying abnormality prior
to surgery did not predict the functional outcome afterwards.
It should be noted that idiopathic slow-transit constipation as described
above is an uncommon condition occurring in <5% of patients referred to
Glasgow Royal Infirmary for consideration of surgery for constipation. In
reports from the Cleveland Clinic and Sweden the corresponding figures
for patients fulfilling the criteria of delayed colonic markers and normal
evacuation as assessed by cinedefaecography or electromyography [22]
were 13% and 7%, respectively. The authors have not found anorectal man-
ometry, electrophysiology, or balloon evacuation studies helpful in this
group of patients when making a decision as to whether these patients
should have surgery.
2.1.1.1. Surgery
The most effective operation for idiopathic slow-transit constipation is
colectomy and ileo–rectal or ileo–sigmoid anastomosis. The outcome after
surgery, however, is unpredictable with reported success rates varying from
30%–100%, reflecting the clinical and physiological heterogeneity of the
patients included in these reports. Despite this, some firm conclusions can
be made. Fewer than 50% of patients who have a colectomy performed on
the basis of clinical criteria alone, without the use of investigations, have a
satisfactory outcome [3,23]. Further, failure after surgery often results in an
ileostomy. Consequently, patients should never be subjected to surgery
without investigation. In contrast, there have been several reports of the
outcome after surgery based upon the selection criteria of a delay in colonic
markers and a normal proctogram. These show consistently high success
rates for the operation of over 90% [22,24–26]. Patients must be clearly con-
sented prior to surgery that there is a risk of either continuing constipation
or intractable diarrhoea that may in turn lead to the need for a permanent
stoma. When performing the colectomy in these patients it is the authors’
practice to leave a short segment of sigmoid colon, preferring to risk a
degree of residual constipation rather than incapacitating diarrhoea.
In an attempt to overcome the risk of intractable diarrhoea, segmental
colonic resection has been advocated [27,28] and when it is based on
scintigraphic transit studies then the outcome may be comparable to total
266 I.G. Finlay and A.A. Renwick
13. Surgical Management of Constipation 267
colectomy [29]. Crucially, scintigraphic transit studies have suggested that
there may be different patterns of segmental slow-transit constipation with
the abnormality restricted to either the right colon or the distal large bowel
[30] (Figure 13.3). This later abnormality has been especially identified in
those patients who clearly attribute the onset of symptoms to childbirth or
hysterectomy. Patients complaining of posthysterectomy constipation have
been shown to have abnormal colonic motility with mass inaction extend-
ing from the splenic flexure to the rectum [31], leading to the suggestion
that this abnormality is related to an iatrogenic autonomic-nerve injury
during pelvic dissection. A similar abnormality has been shown in patients
with postchildbirth constipation [14,32,33] both on colonic manometry
and bisacodyl-stimulated intraluminal scintigraphy [34]. The difference in
the pathophysiology between idiopathic slow-transit and postchildbirth/
hysterectomy constipation is further emphasized by the observation that
gastric emptying is normal in postchildbirth/hysterectomy constipation and
abnormal in patients with idiopathic constipation [35]. This raises the pos-
sibility that hindgut resection could remove their constipation by removing
all colon from splenic flexure to the anal canal. The disadvantage to such a
management plan were it to fail is that the patient has lost the option of
having an ileal pouch.
In 1990, Malone introduced the alternative surgical approach of ante-
grade colonic irrigation using an appendicostomy [36]. The Malone ante-
grade continent enema (MACE) has since proved to be safe and effective
in children suffering from constipation secondary to spina bifida or ano–
rectal malformations [37]. More recently, it has been used to treat a small
number of adult patients with neurogenic colorectal dysfunction and
chronic idiopathic constipation [38,39]. Further, using a novel scintigraphic
Figure 13.3. Radiolabeled scintigraphy scan demonstrating delay at splenic flexure
after 24 hours. In normal subjects this would be in the rectum.
technique it has been shown to be effective [40] in clearing the bowel. This
technique may have an increasingly important role in the future.
2.1.2. Normal Colonic Transit Study and an Abnormal Proctogram
Videoproctography is the best readily available investigation for identify-
ing abnormalities of evacuation [41]. Newer techniques include dynamic
magnetic resonance proctography [42], dynamic anal endosonography [43],
and scintigraphic proctography but these have either been studied in only
small numbers of patients or remain research tools. Approximately 20%–
30% of patients presenting to a specialist clinic with constipation will have
the combination of an abnormal proctogram and a normal colonic transit
study. Consequently, this is a relatively common clinical problem that
requires a clear management strategy. Proctographic abnormalities may be
broadly defined as anatomical or functional. The former include evidence
of rectocoele, internal prolapse, perineal descent, and atypical herniations
including enterocoele and levator ani defects [44]. The principle functional
defect is that of anismus or puborectalis paradox.
Anatomical abnormalities of the anorectum are predominantly, although
not exclusively, found in female patients in middle and later life. Symptoms
include difficulty in evacuation, a sensation of incomplete evacuation, or a
sensation of weight in the perineum that initially may be described as pain.
Patients may digitally aid defaecation by supporting the posterior wall of
the vaginal or by pushing against the buttock behind the anus. Some may
digitally evacuate the bowel. Patients also often respond positively to the
suggestion that the energy they produce in pushing to achieve evacuation
is strangely lost, resulting in a feeling of exhaustion. On occasions patients
may be aware of prolapse of either the bowel or the vagina. Frequently
patients have already had urological and gynaecological operations includ-
ing hysterectomy or vaginal-wall and bladder-neck repairs. It is wise to
involve these specialists [45] at an early stage and several centres now have
joint pelvic-floor clinics involving all 3 disciplines. It is of note that in some
countries there is emerging the entity of the pelvic-floor specialist.
In broad terms, these anatomical abnormalities are due to wear and tear
and are predominantly secondary to childbirth. It has been shown that even
an apparently normal vaginal delivery results in neuropathy of the puden-
dal nerve with reduced tone in both the external anal sphincter and pub-
orectalis muscles [46,47]. Multiple pregnancies and complicated deliveries
involving the use of forceps or other interventions produce an even greater
degree of injury.The levator ani muscle may be similarly damaged by either
a traction or ischaemic injury to the nerves arising from S2,S3 which course
over the ventral surface of the posterior aspect of the muscle, although
it should be noted that the exact nerve supply to the levator muscle
remains uncertain. It is widely accepted that this is the mechanism that leads
to the development of the appearances of perineal descent syndrome
268 I.G. Finlay and A.A. Renwick
13. Surgical Management of Constipation 269
(Figure 13.4) and eventually those of idiopathic faecal incontinence. Many
of these features are also present in patients with rectal prolapse although
the sequence of events that leads to the development of a prolapse is uncer-
tain. Neuropathy can certainly rapidly lead to a rectal prolapse as evidenced
by reports of a rectal prolapse developing within days of spinal surgery that
involved transection of the cord. With regard to the present discussion, it is
unknown whether a rectal prolapse always begins as an intussusception and
Figure 13.4. Combined proctogram and cystogram that demonstrates perineal
descent, rectocele, and posterior rotation of the urinary bladder.
if it does, then over what time scale. This has important implications with
regard to the selection of patients for surgery who have intussusception
on proctography. The management of the common abnormalities found on
proctography are discussed below.
2.1.2.1. Intussusception/Internal Prolapse
Patients with symptoms of obstructed defaecation frequently have evidence
of infolding of the rectum on videoproctography [48,49] (Figure 13.5). This
appearance is known as internal prolapse or midrectal intussusception.
Over quarter of a century ago it was recognised that some patients with
this feature respond to surgery while others are either unhelped or made
worse [50]. For example, in 1975, Ihre and Seligson observed that patients
with symptoms of prolapse and incontinence had a good result after rec-
topexy but the outcome was poor if patients complained of obstructed
symptoms or had a solitary rectal ulcer. Several surgical groups have since
reported similar results leading to a reappraisal of the indications for
surgery in this condition [51–53]. Indeed, in a recent comparative study it
has been suggested that biofeedback should be used as the initial treatment
for most patients with a rectal intussusception [54]. The reason for this
change in opinion with regard to management is directly related to a better
understanding of the range of normal appearances on videoproctograms.
When infolding of the rectum was initially identified it was assumed to be
the principal cause of symptoms in patients with obstructed defaecation. It
is now recognized that a small degree of rectal infolding may be present in
normal subjects. Further, when it occurs in patients with symptoms of
obstructed defaecation it is probably secondary to recurrent straining
rather than the primary abnormality. The situation is further complicated
by the fact that the infolding may involve only mucosa or include the full
thickness of the bowel wall. In either case, the size of the intussusception
may vary from <1 cm to a prolapse protruding at the anus. It is also now
recognised that very small intussusceptions rarely proceed to overt pro-
lapses, at least over a 10-year observation period [54]. Despite this, an overt
rectal prolapse must have a stage when it is a midrectal prolapse/intussus-
ception which does not reach the anal verge. The clinical picture is further
complicated by the fact that even overt prolapses may be evident only when
the patient strains and can be difficult to diagnose. In conclusion, there are
probably 2 distinct entities: mucosal infolding and small full-thickness intus-
susceptions that are secondary to obssesive straining, and large intussus-
ceptions, which are early prolapses secondary to a pelvic-floor neuropathy.
In order to distinguish these 2 entities, the authors use the following
strategy: all patients in whom the proctogram suggests an intussuscep-
tion proceed to examination under anaesthesia (EUA). An eissenhammer
retractor is inserted into the anal canal and the midrectum is drawn down-
wards using a sponge-holding forcep. When the full thickness of rectum is
easily drawn to the anal margin without tension, the patient is considered
270 I.G. Finlay and A.A. Renwick
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