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72. Moore EE, Cogbill TH, Malangoni MA, et al. Organ injury scaling, II: pancreas duodenum, small bowel,
colon and rectum. J Trauma. 1990;30:1427–1429.
73. Brown CVR, Teixeira PG, Furay E, et al. Contemporary management of rectal injuries at level I trauma
centers: the results of an American Association fr the surgery of Trauma multi-institutional study.
J Trauma Acute Care Surg. 2018;84:225–233.
74. Tyler JA, Welling DR. Historical perspectives on colorectal trauma management. Clin Colon Rectal
Surg. 2018;31:5–10.
75. Cleary RK, Pomerantz RA, Lampman RM. Colon and rectal injuries. Dis Colon Rectum.
2006;49:1203–1222.
214 ANORECTAL DISORDERS
17
Constipation and Dyssynergic
Defecation
Franc¸ois Mion
PH Y S I O L OG I E / E X P L O R A TI O N F O N C T I O N N E L LE D I G E S T I V E – UN I V E R S I T!E LY O N , L Y O N, FR A N C E
17.1 Introduction
Constipation is a very common condition defined according to the Rome IV classification
as a decreased frequency of bowel movements (less than 3 per week), or as difficulty in
passing stools for at least 25% of bowel movements (hard stools, straining efforts, sensation of incomplete evacuation, sensation of recto-anal obstruction, digital or other types
of anal maneuvers to facilitate evacuation).
1
There may be associated symptoms, such as
abdominal distention or bloating, abdominal pain, hemorrhoids, and anal fissure. Its
prevalence depends mainly on the definition of the disorder, and varies greatly between
4% and 27% of the general population, according to studies.
2
Constipation may be a sign of a general neurologic or metabolic disease (Parkinson’s
disease, or diabetic autonomous neuropathy to name two), or an associated sign of
organic digestive disease (colonic cancer, chronic intestinal pseudo-obstruction, etc.).
Many drugs can also be associated with c onstipation.
3
These organic and drug-induced
causes must be eliminated before accepting the diagnosis of idiopathic chronic constipation, which will be the topic of this chapter.
Interestingly, an important discrepancy may be found between the perception of the
patient, the medical diagnosis based on standardized questionnaire, and the objective
measurements such as colonic transit time for example.
4
Moore-Gillon suggested that
constipation meant for the patients difficult or infrequent defecation, or both.
5
In another
rather ancien t study, Probert et al. found, in a population of 731 women, a prevalence of
constipation around 8%, based on the women’s perception, Rome I criteria for constipation, and measurement of colonic transit tim e. However, only a small proportion of cases
(11/731!) had a concordant diagnosis of constipation based on the evaluations.
6
It is thus
clear from these results that it is important to listen carefully to the patients’ complaints in
order to provide an adapted therapeutic answer to their problem.
Chronic constipation may alter profoundly the quality of life of the patients, both from
a physical and functional point of view. In particular the asso ciation of abdominal pain, or
discomfort, is frequently a major source of complaint from patients with constipation: the
Anorectal Disorders.
https://doi.org/10.1016/B978-0-12-815346-8.00017-5
© 2019 Elsevier Inc. All rights reserved.
215
quality of life in this group of patients is much more negatively impacted than in patients
in whom constipation is not associated with significant abdominal pain.
To delineate a pertinent therapeutic algorithm for chronic constipation, it is recom-
mended to assess both colonic function (colonic transit) and anorectal function.
7,8
From
these assessments patients should then be classified into four pathophysiological groups:
patients with slow transit constipation, patients with disorders of the defecation process
(or pelvic-floor disorders), patients with mixed slow transit and pelvic-floor dysfunction,
and patients with normal transit constipation and normal defecation process.
17.2 Pathophysiology
The causes of constipation are various and often multifactorial. The concepts of constipation or defecatory disorders may vary between countries and cultures, and are influenced by social, cultural, and dietary customs. Psychological factors also represent a
very important determinant of chronic constipation, and can be influenced by different
events occurring during childhood, including sexual traumas.
The assessment of colonic transit can be performed using various techniques, as will be
described later. Slow transit can be a consequence of altered colonic nerves or muscles,
but also of a limited alimentary intake, especially when the amount of dietary fiber is
drastically reduced. Once again, psychogenic causes of slow colonic transit may be present. Abnormalities of the myenteric plexus of the colon, as well as a reduced number of
interstitial Cajal cells has been found in some patients with slow transit constipation.
These abnormalities may be limited to the colon or associated with widespread gastrointestinal motility disorders. In addition to colonic motility disorders, sensory disturbances
(e.g., decreased response to distention) may also be present in some cases of constipation
associated with slow colonic transit.
7
Defecatory disorders can be the consequence of structural abnormalities of the pelvic
floor, such as excessive perineal descent, rectocele, rectal intussusception or complete
rectal prolapse, and solitary rectal ulcer syndrome. These pelvic floor disorders may be
in some cases the consequence of prolonged excessive straining for years. Defecatory dysfunction is the consequence of insufficient rectal (or abdominal) propulsive forces and/or
increased anal resistance to evacuation: impaired rectal evacuation is the result of these
functional disturbances. Several other synonyms are used to describe the same defecatory
disorder: outlet obstruction, dyssynergia, anismus, obstructed defecation, and terminal
constipation. It must be stressed that defecatory dysfunction, as evaluated in a motility
lab, may be found in a significant number of asymptomatic subjects. Stool form and
consistency, very intuitively, may also influence the defecation process through rheologic
perturbations, but this parameter is difficult to explore and integrate into the pathophysiological evaluation of defecatory disorders. It is also very important to remember that
there is no gold standard for the diagnosis of defecatory disorders and that the results
of various tests may not be concordant.
9
216 ANORECTAL DISORDERS
17.3 Clinical Evaluation
A complete anamnesis is mandatory, including past medical and surgical histories, dietary
habits, and current medications that can induce or aggravate constipation. The clinician
should insist on a precise description of symptoms (pain, bloating, frequency of bowel
movements, straining efforts, sensation of anal blockade or incomplete rectal evacuation,
digital or other maneuvers to facilitate defecation). A bowel diary to be filled in for
1–2weeks may help to obta in objective data. The form and consistency of stools should
be evaluated on the same diary using the Bristol stool form scale, which gives a first idea of
the colonic transit time.
10
It is also important to note the past and present use of laxatives:
alternating constipation and diarrhea may be the consequence of the use of irritant
laxatives.
Clinical examination must include a complete perineal and anal inspection, to look for
lesions such as hemorrhoids or anal fissure. Perineal inspection and digital rectal examination must be performed both in the resting state and during dynamic maneuvers of
straining and pushing (or simulation defecation) . This meticulous perineal examination
will help to identify pelvic-floor disorders, as well as pelvic-floor dysfunction such as rectoanal dyssynergia. The presence of stools in the rectum (including the finding of a fecaloma) is also an important positive indicator of defecatory disorder.
In the situation of first-line patients, these first steps are sufficient in most cases, and
the situation will improve after dietary modifications, simple advice on how to optimize
defecation and first-line laxatives.
11
17.4 Functional Testing
In cases not responding to this first line of therapy, additional functional testing is recommended, in order to understand the pathophysiological mechanisms and orient the
therapy.
Complementary to the perineal clinical examination, tests are recommended to evaluate the defecation process. Depending on centers and countries, one or several tests may
be used: balloon expulsion test (BET), anorectal manometry (ARM), and defecography.
More complex evaluation of suspected pelvic-floor disorders may be done using magnetic
resonance imaging (MRI) defecography, colpo-cysto-defecography or dynamic perineal
ultrasonography. As mentioned earlier, the results of these tests have to be interpreted
with caution, including the global context of the patient: several tests may not be concordant, patients’ privacy should be respected as much as possible, and patients’ complaints,
not images, should be treated.
The rectal BET may be performed, ideally alone, with the patient sitting on a private
commode: the current standardized protocol recommends a balloon filled with 50 mL
of warm water, and a time to expel of less than 1–3 min.
12
However, the performance of
this test in terms of negative or positive predictive values for the diagnosis of defecatory
Chapter 17 • Constipation and Dyssynergic Defecation 217
disorders is variable and not always concordant with other tests.9The BET can be also
performed during ARM.
ARM is the most widely test for the evaluation of rectoanal function. Conventional ARM
(measurement of single point pressures in the rectum and the canal anal) is progressively
being replaced by high-resolution manometry (continuous pressure measurements along
the rectum and the anal canal, represented as color plots or pressure topography),
although the potential advantages of this new technique compared to the conventional
ARM have not been demonstrated at this stage. ARM enables the testing of anal resting
tone, the strength or vigor of the voluntary anal sphincter squeeze and during a cough
effort (cough reflex), and the ability of the pushing maneuver (or defecation simulation)
to increase rectal pressures and decrease anal pressures. Rectal sensitivity to balloon distention is also tested during ARM, as well as the presence of a rectoanal inhibitory reflex in
response to rapid rectal balloon distention. Many different protocols are used throughout
the world, and the recent consensus statement of the International Anorectal Physiology
Working Group (IAPWG) proposed a standardized protocol for ARM, based essentially on
expert opinions (
Fig. 17.1).
12
High-resolution ARM may help to identify structural pelvicfloor disorders such as rectal intussusception or perineal descent, while 3D highdefinition ARM provides relevant information on the asymmetrical nature of pressures
within the anal canal
13,14
(Fig. 17.2). Once again, interpretation of ARM findings must
be interpreted with the knowledge of the wide variability of possible results in pa tients
and asymptomatic subjects,
15
and the often poor concordance of the diagnosis of rectoa-
nal dyssynergia between ARM and other test such as BET or defecography.
Barium defecography allows for a rather physiological testing of the defecatory process, except for the reproduction of stool consistency. MRI defecography tends to be preferred by radi ologists as it is nonirradiant and allows for complete imaging of the pelvic
organs. However, MRI defecography is performed supine, a less physiological position
that may limit the identification of some pelvic-floor disorders.
Colonictransit is an important determinant of bowel movements. The Bristol Stool Form
scale has clearly demonstrated the relationship between stool form and colonic transit
time.
10
Colonic transit time can be measured very simply and cheaply using radiopaque
markers. Several protocols have been published, and we recommend using those that limit
the number of abdominal radiographs (e.g., only one for the Dorval protocol). Other techniques such as colonic scintigraphy or the wireless motility Smartpill capsule may be used.
The Smartpill capsule offers the advantage to measure gastric and small bowel as well as
colonic transit times, based on pH and temperature variations (
Fig. 17.3).
16
Colonic
manometry may be useful in very specific cases, to try to confirm colonic inertia, for example, before colonic surgery in cases of severe chronic constipation.
17
17.5 Therapeutic Management
Based on an accurate synthesis of symptoms, clinical exami nation and adapted functional
testing when necessary, one should be able to describe idiopathic chroni c constipation as
218 ANORECTAL DISORDERS
being the cause of slow colonic transit, defecatory disorders, both abnormalities, or neither. This will then help to orient the treatment.
3
17.5.1 Treatment Options for Defecatory Disorders
Surgical options should be discussed in defecatory disorders where a typical pelvic-floor
disorder is thought to be responsible for the symptoms (e.g., rectocele). In all other situations, defecatory disorders should be treated first by suppositories or enemas
Time (min)
Stabilization – 3 min
Rest – 60s
30s recovery period
between each short
squeeze
30s recovery period
between each cough
and push
60s recovery period
after long squeeze
Short squeeze – 5s
Short squeeze – 5s
Short squeeze – 5s
Long squeeze – 30s
Cough
Cough
Push –15s
Push –15s
Push –15s
RAIR
Rectal sensory testing
Balloon expulsion test
0
1
2
3
4
5
6
7
8
9
10
11
12
FIG. 17.1 Standardized protocol for high-resolution anorectal manometry, as proposed by the International
Anorectal Physiology Working Group.
12
Chapter 17 • Constipation and Dyssynergic Defecation 219
PR muscle
EAS
A
B
C
Post
Ant
Ant L R APost
5,2
4,8
4,4
4,0
3,6
3,2
2,8
2,4
2,0
1,0
1,2
0,8
0,4
0,0
–0,4
–0,8
HRM 2D/3D
FIG. 17.2 Typical asymmetrical aspect of anal sphincter pressures as recorded with 3D high-definition anorectal manometry, during voluntary squeeze in a
healthy subject. The drawing on the left represents the corresponding anatomy (puborectalis muscle above the external anal sphincter), the figure in the
middle represents a pressure cylinder, and the image on the right the cylinder opened anteriorly, with the maximal pressure in the posterior and upper part of
the anal sphincter corresponding to the puborectalis muscle activity, and the anterior and lower maximal pressure corresponding to the activity of the
external anal sphincter. PR, puborectalis; EAS, external anal sphincter.
220 ANORECTAL DISORDERS
Temperature
ColonStomach Small bowel
GET:
4 h
SBTT:
5 h
CTT:
21 h
Time (h)
37°C
25°C
pH 6
pH 3
pH
Pressure
FIG. 17.3 The SmartPill capsule allows measurement of temperature, pressure, and pH along the gut after ingestion: the recorded data allows measurement of
gastric (GET), small bowel (SBTT), and colonic transit times (CTT), as shown on the graph (times indicated in hours).
Chapter 17 • Constipation and Dyssynergic Defecation 221
(in addition, if needed, to measures for improving colonic transit time and softening
stools, see following section): these measures clearly improve patients’ satisfaction compared to placebo.
18
Biofeedback pelvic-floor retraining should be proposed early in the
course of defecatory disorders management. These rehabilitation techniques, which
teach the patients to increase adequately rectal pressures and anal relaxation during push
maneuvers, have been shown to be more efficient than laxatives.
19
A recent study found
the combination of biofeedback and gas-releasing suppositories (Eductyl) to be more efficient than gas-releasing suppositories alone.
20
Several studies have tried to identify the
predictive factors for successful biofeedback therapy for defecatory disorders, but it seems
that the motivation of the patient and the therapist are the most important ones.
21
As a
whole, biofeedback therapy is clearly an efficient therapy for defecatory disorders; however, practices are highly variable around the world and may impair the results on an individual basis. Botulinum toxin injection of the external anal sphincter may be of use in
cases of defecatory disorders clearly associated with anismus (paradoxical contraction
of the puborectalis muscle and external anal sphincter). A recent systematic review found
this therapy to have an efficacy limited over time (less than 3 months), while repeated
injections may provide better sustained results.
22
The addition of laxatives (see below)
is very often useful to improve defeca tory disorders.
17.5.2 Treatment Options for Slow Transit Constipation
Medical management of slow transit constipation should first rely on diet and lifestyle
modifications, if needed. Despite a rather low level of evidence, increasing the amount
of dietary fiber should be recommended, especially in patients with a low baseline consumption of fiber (a raw dietary evaluation should be done). Soluble fiber such as psyllium
can be added to the regular diet and may induce less bloating and gas than insoluble fibers
such as bran. A progressive increase of fiber intake should be recommended to patients in
order to limit side effects. Increasing the amount of liquid taken per day is probably useless, while increasing physical activity may help somewhat. Specific diets, such as the low
FODMAPS (Fermentable Oligosaccharides, Disaccharides Monosaccharides And Polyols)
diet, may be useful, especially when constipation is associated with abdominal pain and
bloating (the efficacy of this diet has been proven in patients with irritable bowel syndrome with constipation).
23
In addition to soluble fibers, first-line laxatives are regrouped under the term osmotic
laxatives. These laxatives are hypertonic and induce intestinal hydric secretion, favoring
softer stools and diarrhea. There are three categories of osmotic laxatives: polyethylene
glycols (PEG), poorly absorbed carbohydrates (such as lactulose or sorbitol), and magnesium salts (magnesium hydroxide). The efficacy (and compliance) of these laxatives vary
between patients and with time. It may be helpful in patients needing long-term treatment to switch from one category to another and back. A Cochrane meta-analysis has
shown PEG to be superior to lactulose in terms of efficacy and side effects.
24
Lactulose
and other poorly absorbable sugars are subject to bacterial fermentation in the colon: this
222 ANORECTAL DISORDERS
is part of their therapeutic effect, but it also leads to increased intestinal gas production
(hydrogen and methane).
Liquid paraffin (mineral oil) has been suggested as an efficient treatment for chronic
constipation and was found to be superior to lactulose in one small study in children.
25
Anal soiling and itching are possible consequences, but the tolerance is estimated to be
excellent.
26
Stimulant laxatives such as bisacodyl (pill or suppositories) or sodium picosulfate are
mostly considered as rescue medication. They stimulate propagated colonic contractions
and have antiabsorptive and secretory effects. Recent studies have shown that they can be
used safely on a regular basis, without significant side effects.
27
The potential role of these
drugs in the induction of lesions to the enteric nervous system has not been convincingly
demonstrated, and the long-term use of these drugs seems possible, as long as abuse and
dependence are not evidenced (as may occur in some cases).
3
Pyridostigmine is an inhibitor of the synaptic cholinesterase, thus prolonging the effect of acetylcholine. Recent
studies suggested that this drug (in doses up to 360 mg per day) may be of interest in constipation associated with diabetes mellitus and in systemic sclerosis.
28,29
Prucalopride is
as serotonin 5-HT4 receptor agonist that stimulates digestive motility, especially colonic
contractions. This drug is available in Europe for the treatment of chronic constipation
resistant to the usual laxatives. It does not seem to have any cardiovascular effect (such
as increasing the QTc interval as observed previously with cisapride, another 5-HT4 receptor agonist now withdrawn from the market).
30
Secretagogues have been used to generate new drugs that increase the electrolytes and
water secretion from the intestine. There are two drugs that are available in some countries but not all: lubiprostone (derived from prostaglandin E1) and linaclotide (activator of
the guanylate cyclase expressed in the brush border membranes of digestive epithelial
cells). Both drugs are poorly absorbed and act locally within the gut. They are available
to treat chronic constipation and irritable bowel syndrome with constipation (IBS-C).
Opioid-induced constipation is a well-known side-effect of opioid therapy, whether for
cancer or noncancer pain. When the usual laxatives fail, μ-opioid receptor antagonists
may be used. Several drugs are on the market depending on the country (naloxegol,
methylnaltrexone, naloxone, almivopan, axelopran, and naldemedine). A recent metaanalysis indicates that these drugs are more efficient than placebo with an overall number
to treat of 5 (95% CI: 4–7), with side effects such as diarrhea, nausea, abdominal pain, or
vomiting, which were more frequent in patients treated with the actual drugs compared to
placebo.
31
Enemas or transanal colonic irrigations (TACI) may be considered in patients with constipation resistant to laxatives. Specific systems, such as the Peristeen irrigation device
developed by Coloplast, have been shown to be efficient, especially in neurologic patients
(spinal cord injury, spina bifida, etc.), and even more so when fecal incontinence is associated with constipation. Depending on studies and the causes of constipation, the success rate of TACI (meaning the adherence of patients to repeated irrigations over time)
varies between 20% and 60%.
32
Careful patient select ion, evaluation, and proper training
Chapter 17 • Constipation and Dyssynergic Defecation 223
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