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Initial Evaluation of Constipation

Last updated on November 21st, 2021

Constipation is a common and subjective symptom that can be related to a multitude of factors, including, dietary, psychological, cultural, anatomic, and functional aspects. In addition, constipation is still surrounded by misconceptions and taboos that hamper an objective evaluation and encourage self-medication that is not always innocuous to the patient.

The definition of constipation varies tremendously among both patients and physicians. When adults not seeking health care were asked to define constipation, their most frequent definitions included “straining” (52%), “hard stools” (44%), “infrequent stools” (32%), as well as terms such as “abdominal discomfort” and “sense of incomplete evacuation.” According to Ruben, 62% of the general population believes that a daily bowel movement is a sign of good health; they may report constipation if they fail to achieve a daily bowel movement or even if they fail to achieve a bowel movement at their usual time each day. Definitions used by physicians include (1) unspecific self-reported symptoms, (2) stool frequency of less than three bowel movements per week, and (3) whole gut transit time of more than 68 hours. Ultimately, the Rome criteria have been accepted as a comprehensive standardized definition for constipation:

I. The presence of at least two of the following complaints, without the use of laxatives for at least 12 months:

1. Straining during >25% of bowel movements

2. Sensation of incomplete evacuation with >25% of bowel movements

3. Hard or pellet-like stools with >25% of bowel movements

4. Less than three bowel movements per week

II. Fewer than two stools per week on a regular basis.

These criteria fulfill the definition of constipation, even in the absence of any other symptom.

Constipation is a common symptom in both the general population and in medical practice. In the general population, the prevalence of constipation is reportedly in the range of 2% to 34%, depending on demographic factors, the sampling situation, and the definition used. This symptom accounts for approximately 50% of the patient complaints at specialists’ offices. Fortunately, the majority of individuals who seek medical care for constipation do not have a life-threatening or disabling disorder, and the primary need is for symptom control.

The prevalence of constipation is three times more common in women, and in most studies shows a marked increase after the age of 65. Accordingly, in a longitudinal survey of the self-reported bowel habits of 14,407 adults in the United States, Everhart et al reported that women were more likely than men to report constipation (20.8% vs. 8.0%, respectively) and infrequent defection (9.1% vs. 3.2%, respectively). In addition, older respondents reporting constipation were more likely to use laxatives or stool softeners than younger respondents. In a survey on 10,018 adults, Stewart et al noted an overall prevalence of constipation of 14.7%. When analyzed by subtype, the prevalence was 4.6% for functional constipation, 2.1% for irritable bowel syndrome, 4.6% for outlet obstruction, and 3.4% for the association of outlet obstruction and irritable bowel syndrome. Outlet obstruction alone or associated with irritable bowel syndrome was the most common subtype among women, with a female-to-male ratio of 2.27:1.65.

Constipation is a common and serious problem in women of childbearing age, although the reason for a female preponderance has yet to be explained. It has been suggested that in females, steroid progesterone may decrease the levels of the polypeptide motilin, which may influence progression of food through the bowel. Preston et al reported elevated prolactin levels in young constipated women, although this finding has not been reproduced in other studies. In addition, gynecologic surgery, particularly hysterectomy, has been associated with constipation. The precise link between slow-transit constipation and hysterectomy remains obscure.

Possible factors include hormone variation, postoperative depression, and most probably damage to the pelvic parasympathetic and hypogastric nerves and the pelvic plexus during resection of the ligament of the uterus. In fact, denervation hypersensitivity to the carbachol provocation test in the rectosigmoid has been demonstrated in some patients with severe constipation after hysterectomy, suggesting dysfunction in the autonomic innervation of the hindgut. The association of urinary and sexual dysfunction in patients undergoing pelvic surgery seems to support this theory Other risk factors for constipation include inactivity, low calorie intake, low income, low education level, depression, and sexual abuse.



To address the broad spectrum of symptoms involving constipation, an extensive questionnaire is recommended. Questioning must be specific and must emphasize the symptom the patient considers most distressing. The main complaint can be infrequent bowel movements, difficult evacuation (straining, hard stools, feeling of incomplete evacuation), symptoms suggesting irritable bowel syndrome (bloating, abdominal pain), or a combination of all these symptoms.

When constipation occurs later in life, the symptom may be of chronic or recent onset. Constipation of recent onset, specifically if less than 2 years, is frequently related to secondary causes, and exclusion of organic colonic and extracolonic disorders, including malignancy, is mandatory Conversely, this is a lifelong symptom in most patients who have constipation due to congenital disorders such as Hirschsprung’s disease or meningocele. Typical clinical manifestations of obstructed evacuation include straining, tenesmus, and the sensation of incomplete evacuation as well as the frequent need for suppositories, enemas, or digitation. It is important to ask the patient which maneuvers) are used to assist in defecation.

Vaginal digitation suggests a rectocele, whereas massage lateral to the anus suggests poor rectal contractility. Patients with cul-de-sac hernias may report leaning forward on the toilet seat, suggesting that the patient is trying to tilt the enterocele forward off the rectum. In fact, patients with a sigmoidocele may report the need to press the lower abdominal quadrant in order to have a bowel movement. One must remember that any organ pressing on the mechanoreceptors adjacent to the rectum may give the patient the perception of impending defecation. These patients frequently have a history of previous treatment for other anorectal conditions associated with straining such as rectocele, descending perineal syndrome, solitary rectal ulcer syndrome, rec-toanal intussusception, or prolapse.

Table: Wexner constipation scoring system (minimum score, 0; maximum score, 30)

Symptom Score
Frequency of bowel movements  
1-2 times per 1-2 days 0
2 times per week 1
Once per week 2
Less than once per week 3
Less than once per month 4
Difficulty: pain evacuation effort  
Never 0
Rarely 1
Sometimes 2
Usually 3
Always 4
Completeness: feeling incomplete evacuation  
Never 0
Rarely 1
Sometimes 2
Usually 3
Always 4
Pain: abdominal pain  
Never 0
Rarely Sometimes 1
Usually 3
Always 4
Time: minutes in lavatory per attempt  
Less than 5 0
5-10 1
>10-20 2
>20-30 3
>30 4
Assistance: type of assistance  
Without assistance 0
Stimulant laxatives 1
Digital assistance or enema 2
Failure: unsuccessful attempts for evacuation per 24 hours  
Never 0
1-3 1
>3-6 2
>6-9 3
>9 4
History: duration of constipation (yr)  
0 0
1-5 1
>5-10 2
>10-20 3
>20 4

The Rome criteria are intended to provide a diagnostic standard of constipation but are not intended for evaluation purposes. Various scoring systems have been developed to uniformly assess the severity of constipation. The Wexner score is based on eight parameters: frequency of bowel movements, difficult or painful evacuation, completeness of evacuation, abdominal pain, time in minutes per attempt for evacuation, type of assistance (laxatives, digitation, or enema), number of unsuccessful attempts for evacuation per 24 hours, and duration (years) of constipation. Based on the questionnaire, scores ranged from 0 to 30, with 0 indicating normal and 30 indicating severe constipation (Table Wexner constipation scoring system).

According to the authors’ experience with 232 patients, the proposed scoring system correlated well with objective physiologic findings. Another proposed instrument consists of 12 items assigned to three subscales of symptoms: stool, rectal, and abdominal. The instrument has been shown to be internally consistent, reproducible, valid, responsive to change, and therefore suitable to assess the effectiveness of treatment for constipation. Another symptom scoring questionnaire was validated for chronic constipation by Knowles et al. This questionnaire is composed of 11 questions, and in a study of 71 patients and 20 asymptomatic controls, a strong correlation was found with the Wexner score. Although at present in clinical practice symptom analysis does not adequately differentiate major pathophysiologic subgroups, at least two scoring systems have been developed to uniformly assess the severity of constipation.

In a study comparing symptoms with physiologic findings, Glia et al evaluated 134 patients with symptom registration, anorectal manometry, electromyography, colonic transit time measurement, and defecography. In this study, three symptoms had an independent value for the diagnosis of slow-transit constipation: infrequent evacuation (≤ 2 stools per week), laxative dependence, and a history of lifelong constipation. Patients with pelvic floor dysfunction, compared to those with normal pelvic floor function, have a higher prevalence of backache and a lower prevalence of normal stool frequency, heartburn, and a history of anorectal surgery. These authors concluded that symptoms are good predictors of transit time but poor predictors of pelvic floor function in patients with constipation.

Koch et al also addressed the issue of whether detailed symptom analysis would help to identify pathophysiologic subgroups in chronic constipation. These authors studied 190 patients with chronic constipation through symptom evaluation, transit time measurement, anorectal manometry, and defecography. They found that infrequent bowel movements alone have a low specificity for slow-transit constipation, and are of little value in the definition of chronic constipation. The symptom “necessity to strain,” however, had a good sensitivity (94%) in the definition of chronic constipation. A sensation of obstruction and digital evacuation were relatively specific, but insensitive for disordered defecation. The authors concluded that symptoms of chronically constipated patients are not helpful to differentiate pathophysiologic subgroups of chronic constipation.

In a study of 108 constipated patients, Mertz et al verified the existence of three symptom-based subgroups: slow transit, irritable bowel syndrome, and pelvic floor dysfunction. In addition, they assessed whether these subgroups corresponded to differences in colonic transit studies and anorectal sensorimotor function (anorectal manometry, electromyography, and rectal sensory testing). According to these authors, slow transit and irritable bowel syndrome symptoms correlated well with expected physiology. Conversely, pelvic floor dysfunction symptoms and physiology did not correlate. These authors, however, did not include defecography in their study, which would probably have affected the final diagnostic rate.

In the assessment of constipation, it is imperative to ask if the patient has already experienced episodes of incontinence to gas or stool. Anal incontinence is frequently an underreported condition, and, in fact, many constipated patients have symptoms related to sphincter and pelvic muscle denervation due to chronic straining. In this situation, the questionnaire should also assess the frequency and type of incontinence and its effect on the patient’s quality of life.

Constipation is a major problem in the management of patients with spinal cord injury. The mechanisms involved include lack of a conscious urge to defecate, body immobilization, motor paralysis of abdominal and pelvic muscles, and possible motor alterations at the colon, rectum, and anus. The loss of the reflex activity regulation of the anorectum from cerebral input results in fecal impaction and incontinence as the rectum spontaneously evacuates its contents after stimulation by distention.

Physical Examination

Physical examination must be thorough and complement the history in order to exclude systemic etiology. Evidence of systemic illness, including neurologic or muscular deterioration, and endocrine or metabolic disorders, should be sought. In addition, special attention should be directed to the abdominal and anorectal regions.


The abdominal examination may detect excessive stool or gaseous distention and the presence of surgical scars that are evidence of neoplasic or inflammatory bowel diseases. Palpation may reveal a soft mass in patients with a dilated rectosigmoid filled with stool, a tender mass in the left lower quadrant, suggestive of a diverticular disease, or a hard mass that is more characteristic of a neoplasm. Percussion can differentiate gaseous distention from ascites. Finally, auscultation may reveal hyperactive waves in patients with abdominal distention, which can be visualized in the relaxed patient and characteristic of partial bowel obstruction or hypoactive or absent ileal sounds.

Perineum and Anorectum

Both the lateral decubitus and prone jackknife positions are adquate for routine anorectal examination. Although the prone position allegedly provides wider exposure, the left lateral decubitus is a good alternative and better accepted by patients, particularly the elderly or those otherwise incapacitated. Occasionally, however, in order to reveal a rectal prolapse, it may be necessary to place the patient in a squatting position.

The anorectal examination should begin by inspection of the patient’s undergarment and perineal skin for evidence of fecal soiling. Soiling may result from overflow incontinence associated with fecal impaction (“overflow or paradoxical fecal incontinence”), especially in elderly patients. This situation must be differentiated from true incontinence due to sphincter dysfunction and “humid anus” or pseudoincontinence, which is caused by hemorrhoidal prolapse, pruritus ani, perianal fistula, rectal mucosal prolapse, and anorectal venereal diseases, and should be excluded. Perineal examination will exclude anatomic causes of constipation such as tumors, stenosis, fissures, or an ectopic anus.

Increased perineal descent can also be estimated during physical examination by observing the perineum during the Valsalva maneuver with the patient in the left lateral position with the buttocks separated. A perineometer, an instrument consisting of a freely moving graduated cylinder within a steel frame positioned on the patient’s ischial tuberosities, has also been used. Neither method is physiologically appropriate, as evaluation is undertaken with the patient in the lateral decubitus position and during feigned, rather than actual, expulsion of intrarectal contents. Defecography criteria include perineal descent exceeding 3.0 cm during maximal push effort as compared to that measured at rest (increased dynamic perineal descent) and perineal descent exceeding 4.0 cm at rest (increased fixed perineal descent).

The perineal descent syndrome is considered a component of a vicious cycle involving excessive and repeated straining, protrusion of the anterior rectal wall into the anal canal, a sensation of incomplete evacuation, weakness of the pelvic floor musculature, more straining, and further pelvic floor weakness. Excessive perineal descent is a physical sign indicative of pelvic floor weakness. However, it may merely represent one facet in a constellation of varied symptoms and findings. Patients with abnormally increased perineal descent may present with rectal prolapse, partial or major incontinence, obstructed evacuation, solitary rectal ulcer syndrome, or vague symptoms of incomplete evacuation or rectal pain. Potential surgical disorders such as large nonemptying rectocele, enterocele, or sigmoidocele may coexist.

During simulated defecation, the anal verge should be observed for any patulous opening or rectal prolapse. Patients with constipation may have signs of anal incontinence during physical examination due to progressive neural injury related to chronic straining or an associated neuromuscular lesion due to childbirth. Occasionally, fecal incontinence is suspected only during physical examination or even during physiologic testing. This may occur due to the patient’s embarrassment and unwillingness to seek medical therapy or as a subclinical finding.

Cutaneous sensation around the anus may be absent in patients with neurogenic disorders and may also indicate the level and location of the lesion. An intact bilateral anal reflex, as tested by a light pinprick or scratch, demonstrates that innervation of the external sphincter mechanism is present. Fecal impaction is often noted in children and elderly individuals with symptoms of severe constipation and soiling (paradoxical fecal incontinence). Constipated patients often have hard stool in the rectal vault. Patients with Hirschsprung’s disease usually have an empty contracted distal rectum.

The next step is gentle palpation with a well-lubricated gloved index finger to evaluate resting tone. The lower rounded edge of the internal anal sphincter can be palpated on physical examination at approximately 1.2 cm distal to the dentate line. The entire circumference of the anorectum should be palpated by gentle circum-anal rotation of the examining finger to assess the integrity of the anorectal ring. This is a strong muscular ring that represents the upper end of the anal sphincter, more precisely the puborectalis, and the upper border of the internal anal sphincter around the anorectal junction.

In patients with spine lesions, return of anal resting tone after digital examination is characteristically very slow. The groove between the internal and external anal sphincter (intersphincteric sulcus) can be visualized or easily palpated. Distinction between internal and external anal sphincter hypertonicity can be estimated by inducing relaxation, which can usually be accomplished by prolonging the examination while talking to the patient; hypertonicity is most likely due to striated muscle hyperactivity Digital examination should include a full 360-degree sweep of the rectum, including the posterior presacral hollow and the pelvic sidewalk.

During dynamic palpation, the examiner should note both the increase in anal canal tone and the mobility of the posterior loop of the puborectal muscle during squeeze. To assess the presence of paradoxical puborectalis syndrome, the patient is asked to strain while the examiner’s finger is kept in the rectum. Patients with paradoxical puborectalis syndrome will squeeze and some will have intermittent contractions, rather than the Valsalva maneuver. Although the physical examination may be suggestive of paradoxical puborectalis contraction of the external anal sphincter and puborectalis, the patient’s embarrassment may cause a “paradoxical reaction” and the diagnosis is usually reached only after anorectal physiology investigation. Acute localized pain triggered by pulling or compressing the border of the puborectalis muscle is a feature of levator spasm syndrome.

The presence of a rectocele in females can be assessed during physical examination by curving the examining finger and pressing it against the anterior rectal wall until it appears in the vagina, on the other side of the perineal body. This anterior herniation of the rectal wall is much more common than the posterior type, particularly in females in whom the rectovaginal septum is weakened by factors such as multiparity and traumatic vaginal delivery. Rectoceles are found in up to 70% of asymptomatic women; therefore, care must be taken to avoid overtreating this entity, whether found during physical examination or on videodefecography.

The clinical history can be highly suspicious when patients describe the need either to press the posterior vaginal wall or to do rectal digitation to assist defecation. Recto celes can be found in up to 45% of patients with emptying disorders due to nonrelaxing puborectalis syndrome. This type of rectocele usually represents a compensatory mechanism due to the functional closure of the anal canal during attempted defecation and consequent high intrarectal pressure. This finding is of primary importance because, under these circumstances, surgical treatment of a rectocele will fail; instead, biofeedback should be indicated.

Rectal bulging as a result of an internal prolapse may present as a rectocele. Internal prolapse can be palpated by the examining finger as a descending mass during straining on digital examination. Intrarectal and rectoanal intussusception represent initial phases of rectal prolapse: a fold develops in the rectal wall during push, prolapsing into the rectum, and subsequently the intussusception descends to obstruct the anal canal, finally becoming an external prolapse. These findings must be interpreted in light of the patient’s clinical history. More advanced degrees of intussusception can cause rectal pain or even lead to solitary rectal ulcer syndrome with elimination of blood or mucus through the rectum.

However, the differential diagnosis can often be made based solely on defecography, which can also determine the size of the rectocele. Moreover, by providing data on rectal emptying, defecography will allow differentiation of a secondary finding from a clinically relevant rectocele. An overt rectal prolapse or procidentia can be diagnosed by conducting the examination while the patient is straining on a commode.

A combined vaginal digital examination can be very helpful; with the patient in a standing position, the examiner’s index finger is inserted into the rectum and the thumb is inserted into the vagina. During this examination the patient should be asked to strain. A peritoneal sac containing omentum or a loop of bowel dissecting the rectovaginal septum can be palpable between the thumb and the index finger, indicating the presence of a peritoneocele or enterocele. This examination can be an effective method of distinguishing among enterocele, vaginal vault prolapse, rectocele, or a combination of these weakened conditions.

Again, defecography is a crucial method of confirming these findings and evaluating their role in the dynamics of defecation. The cul-de-sac or pouch of Douglas can eventually extend caudally between the rectum and vagina in varying degrees even as far as the perineum and become the site of a cul-de-sac or vaginal hernia. The hernia contents can include the omentum, small bowel, and occasionally an elongated loop of sigmoid. Hernias are named according to their location, not their contents. Therefore, strictly speaking, the term cul-de-sac hernia is more appropriate than enterocele or sigmoidocele. However, this latter terminology seems more discriminative and has gained wide acceptance among both colorectal surgeons and gynecologists. Concomitant urogynecologic and colorectal dysfunctions are highly prevalent in a clinical practice. Therefore, it is incumbent upon the colorectal surgeon to develop a working relationship with other clinicians for a comprehensive approach.

Cul-de-sac hernias have been classified as primary when factors such as multiparity, advanced age, general lack of elasticity, obesity, constipation, or increased abdominal pressure are present, and secondary when enteroceles follow previous gynecologic procedures, especially vaginal hysterectomy. The incidence of enterocele at 1 year or more following vaginal hysterectomy ranges from 6% to 25%, although this can be significantly reduced by obliterating the cul-de-sac with suture of the uterosacral ligaments.

Sigmoidocele and enterocele are generally part of a complex entity known as pelvic laxity or pelvic relaxation, which results from weakened supporting tissues of the vagina and pelvic diaphragm. Several defects may coexist including anterior rectocele, rectoanal intussusception or overt rectal prolapse, cystocele, and vaginal or uterine prolapse. Therefore, the clinical relevance of a sigmoidocele or enterocele in this complex syndrome is an important issue to be considered when planning the treatment of these disorders. Consequently, symptoms of pelvic discomfort, sensation of incomplete evacuation, and prolonged straining can be more severe in patients with sigmoidocele. Although more pronounced cul-de-sac hernias can be diagnosed during physical examination as a prolapse of the upper posterior vaginal wall during Valsalva’s maneuver, more accurate assessment of this entity, especially sigmoidocele,became possible only after the advent of defecography

Both anoscopy and proctosigmoidoscopy are useful to exclude anorectal diseases such as neoplasms, rectoanal intussusception, solitary rectal ulcer syndrome, and inflammatory bowel disease. Rigid proctosigmoidoscopy is a more accurate method of measuring the distance from the anal verge, but the average length reached is approximately 20 cm. Flexible sigmoidoscopy has a three to six times higher yield and is more comfortable for the patient. Solitary rectal ulcer syndrome is characterized by the triad of rectal discharge of blood and mucus, a lower anterior benign rectal ulcer, and disordered defecation. The nature of the ulcer is presumably traumatic due to excessive straining, and, in fact, defecography often demonstrates intussusception or paradoxical puborectalis syndrome in these patients.

Rectal Biopsy

Rectal biopsy is required if Hirschsprung’s disease is suspected, and less frequently, in the diagnosis of other systemic diseases such as amyloidoses. A full-thickness rectal biopsy confirms the presence or abscense of ganglionic cells in both Meissner’s submubosal and Auer-bach’s myenteric plexi. Based on a recent histologic review of cadaveric disections, the normal distance of aganglionic bowel wall is 2 cm or less from the dentate line. Therefore, it is important that the biopsy be taken 2.5 to 3.0 cm cephalad to the dentate line to avoid the short aganglionic zone.

Differential Diagnosis

Constipation is a disorder and not a disease. It may be secondary to several diseases, including colonic disease (stricture, cancer, anal fissure, proctitis), metabolic and endocrine disturbances (hypercalcemia, hypothyroidism, diabetes mellitus), neurologic disorders (Parkinson’s disease, spinal cord lesions), or pharmacologic (antidepressive) (Table Etiology of constipation). Therefore, exclusion of both intestinal and systemic organic etiologies is an imperative step prior to referring the patient with functional symptoms to the physiology laboratory. Barium enema or colonoscopy is usually indicated and the primary pathology treated. Additional tests, dictated by the history and physical examination, may be necessary to exclude the above-named diseases.

Table: Etiology of constipation

Poor habits Fentanyl Arsenic
Low fiber diet Morphine Lead
Inadequate fluid intake Nonsteroidal antiinflammatories Mercury
Inadequate exercise Diclofenac Phosphorus
Ignoring call to stool Indomethacin Miscellaneous agents
Situational factors (travel, illness) Nabumetone Barium sulfate
Intrinsic bowel disease Naproxen Thalidomide
Mechanical obstruction Salicylates Alendronate
Neoplasm Sulindac lnterferon-alfa-2b
Inflammation Muscle relaxants and other analgesics Leuprolide
Volvulus Baclofen Levofloxacin
Infection Carisoprodol Ondansetron
Incarceration Tizanidine Pamidronate
Intussusception Tramadol Neurologic disorders
Ischemia Calcium channel blockers Cerebral
Collagen vascular disease Nifedipine Parkinson’s disease
Scleroderma Verapamil Stroke
Amyloidosis Antiarrhytmic drugs Tumor
Anorectal disease Amiodarone Spinal
Anal stenosis Flecainide Cauda equina tumor
Fissure Mexiletine Meningocele
Inflammation Propafenone Spinal cord injury
Pharmacologic agents Lipid-lowering agents Tabes dorsalis
Antidepressants Cholestyramine Multiple sclerosis
Amoxapine Colestipol Paraplegia
Bupropion Lovastatin Peripheral
Clomipramine Provachol Chagas’ disease
Fluoxetine Antihypertensives Hirschsprung’s disease
Maprotiline Diuretics Surgical disruption of nervi erigentes
Mirtazepine Acebutolol Senna toxicity
Paroxetine Clonidine Von Recklinghausen’s disease
Sertraline Guanfacine Autonomic plexus neuropathy
Venlafaxine Antiplatelet Multiple endocrine neoplasia ll-B
Tranquilizers Anagrelide Hypoganglionosis
Alprazolam Hematologic/oncologic drugs Endocrine causes
Clozapine Iron therapy Hypothyroidism
Olanzapine Carbop latin Hypopituitarism
Risperidone Erythropoetin Diabetes mellitus
Neurologic drugs Filgrastim Pheochromocytoma
Bromocriptine Vinblastine Metabolic causes
Felbamate Gastrointestinal drugs Dehydration
Pergolide Aluminum- and calcium-containing antacids Uremia
Valproic acid Mesalamine Hypercalcemia
Narcotics Pancreatin Porphyria
Burtorphanol Sandostatin Pregnancy
Codeine Heavy metal intoxication Hypokalemia

Plain Films

Plain abdominal films can be especially useful in patients complaining of acute abdominal pain and distention. In cases of large-bowel pseudoobstruction, gaseous colonic distention can be massive, particularly in the cecum.

Barium Enema

Barium enema is generally not useful in the diagnosis of chronic constipation and has been replaced by colonoscopy for the screening and evaluation of many diseases, including diverticular disease and colorectal cancer. However, it does have the advantage of providing a permanent record for future evaluation regarding the size, length, and anatomic abnormalities of the colon. In this sense, barium enema is probably superior to colonoscopy. High-quality double-contrast technique and inclusion of lateral rectal views are essential in a good study.

A large dilated (megacolon) elongated or redundant (dolichocolon) colon is frequently found in patients with constipation. In fact, based on studies using continuous colonic perfusion and a dye dilution technique, colonic volumes were approximately 50% greater in constipated patiensts, as compared to controls. In clinical practice, however, megacolon and particularly dolichocolon have been found in healthy individuals; thus, these findings are not truly indicative of severity or of the need for surgery. Normal ranges for the width of the colon can vary considerably, but the upper normal limit of the rectosigmoid in a lateral view of the pelvic brim has been considered as 6.5 cm.

Therefore, barium or water-soluble enema is essential for the diagnosis of megacolon. Similarly, dolichocolon is somewhat poorly defined and has been considered as any case in which the enema-filled pelvic loop rises above a line drawn between the iliac crests. This condition occurs in approximately 50% of patients with a history of constipation exceeding 10 years, compared with 2% in the control group. Patients with a shorter history of constipation fall between these two values. Dolichocolon in constipation can be a reason for an incomplete colonoscopy.


Colonoscopy is a complementary study to a barium enema for exclusion of colonic pathology. Compared to barium enema, colonoscopy has a higher risk of complications and is more expensive, although both are probably comparable in the diagnosis of lesions associated with constipation. In patients with anthraquinone laxative abuse, the rectal mucosa may present with characteristic aspects of melanosis coli, a brown-black spotty coloration due to deposits of lipofuscin in the lamina propria.

Initial Approach

Because the most common causes of constipation are related to misconceptions of normal bowel function and inadequate dietary habits, the initial approach should include careful assessment, reassurance, and simple guidance. Thus, the initial therapeutic schema should include the following:

1. Evaluation of the patient’s expectation and concept of normal bowel frequency in order to understand the complaint and reassure the patient.

2. Dietary assessment (fiber supplementation, increased fluid intake, balanced meals). Meals should be balanced, taken at regular intervals, and contain generous portions of vegetables and fruits. Excessive ingestion of processed carbohydrates should be discouraged. In addition, omission of breakfast may contribute to abnormal bowel function due to inadequacy in elicitation of the gastrocolic reflex. Recommended empirical fiber therapy should include 20 to 40 g of dietary fiber or 10 to 20 g of crude fiber per day. The most inexpensive cereal with the highest concentration of crude fiber is bran. Unprocessed bran, particularly coarser preparations, has high hydrophilic properties that soften the stool and increase its volume, stimulating peristalsis. In addition, an increase in daily fluid intake will increase the efficacy of a high-fiber diet.

3. Physical exercise is encouraged; a simple walk in the morning may be effective.

4. Attention to the call to stool. Environmental factors, such as work or school schedules, are often difficult to change, but patients should be advised that to neglect the call to stool will, through the mechanisms of rectal capacity and compliance, lead to fecal stasis.

5. Use of a diary of bowel habits to include frequency and consistency of stool and ease of defecation and association of symptoms. This diary is important because symptoms very often vary with time, and the severity of constipation may be related to associated events in the patient’s life.

6. Psychological evaluation, when indicated.

This initial trial of empirical therapy is recommended, unless alarming symptoms such as rectal bleeding, abdominal distention, or weight loss are present. These measures facilitate a more thorough evaluation of the severity of symptoms, and patients should be reevaluated through a diary of defecation and symptoms. Furthermore, symptoms may even improve, if they are dietary or psychologically related. If symptoms disappear altogether during this trial, no further evaluation is necessary and treatment should be maintained. If symptoms persist, patients should be referred to the physiology lab for investigation. Thus, patients referred for colorectal physiologic testing generally present with refractory and severe idiopathic symptoms.

Additional Evaluations

Patients with chronic refractory idiopathic constipation must be referred for investigation. The mechanisms responsible for both anal continence and defecation are complex and maintained by the interaction of multiple factors. These factors include stool consistency and delivery of colonic contents to the rectum, rectal capacity and compliance, anorectal sensation, anal sphincter mechanism function, and the pelvic floor muscles and nerves. To adequately evaluate these various aspects, a combination of physiologic studies is usually required, including colonic transit time study, anorectal manometry, defecography, electromyography (EMG), pudendal nerve latency, and small bowel transit study. There is no single test that is pathognomonic; thus, final a diagnosis of functional disorders must be based on a collective interpretation of these studies.

According to Rantis et al, the mean cost to investigate chronic constipation in the United States is $2752 (range, $1150 to $4792), including colonoscopy, barium enema, transit time study, defecography, EMG, and rectal biopsy. These authors pointed out that only 23% of patients benefited from this extensive diagnostic evaluation; therefore, the benefits of this assessment are unclear. However, most studies have shown that physiologic testing adds significant information, leading to a specific diagnosis in 50% to 75% of patients. Furthermore, physiologic testing permits objective assessment and reliable posttherapeutic follow-up of subjective functional colorectal disorders.

Technical variants have been proposed in an attempt to enhance the diagnostic capability of defecography, specifically to assist delineation of deep cul-de-sac pouches, enterocele, and sigmoidocele. In addition to the use of video-recording (videoproctography), systematic instillation of air, barium suspension and a substantial amount of barium paste, and oral ingestion of 150 mL of barium contrast 1 to 3 hours prior to the examination may assist in the delineation of pelvic small bowel loops. More recently, intraperitoneal instillation of 50 mL of nonionic contrast has been proposed; despite the potential risk of complications, peritoneography combined with dynamic proctography can provide better assessment of pelvic floor disorders, particularly peritoneocele with or without enterocele.

The use of a tampon soaked in iodine contrast medium placed in the posterior fornix of the vagina either as an isolated method or combined with a voiding cystography (colpocystodefecography) also helps to assess the depth of the rectogenital fossa and the eventual interposition of intraabdominal content between the rectum and vagina. More recently, by measuring the change in peritoneal-anal distance during evacuation, dynamic anorectal endosonography has been proposed to evaluate enterocele. However, further studies are needed to prove its sensitivity for screening of this disorder. Dynamic pelvic resonance has also been proposed to investigate complex pelvic disorders, particularly in the diagnosis of cul-de-sac hernia and its contents.

A recent comparison by Matsuoka et al of dynamic pelvic magnetic resonance and videoproctography in patients with constipation revealed that, despite a cost of approximately ten times more for dynamic pelvic resonance imaging than for videoproctography, no clinical changes were made. The routine application of dynamic pelvic resonance imaging is not supported, and further studies are warranted in order to establish its exact role.

The correlation between psychological factors and constipation is a well-known fact, both in clinical practice and in the literature. Accordingly, the Minnesota Multiphasic Personality Inventory scores for the “neurotic triad” (hypochondria, depression, and hysteria) are significantly higher in patients with constipation when compared to those with anal incontinence and rectal pain. Organic causes of constipation, however, must not be overlooked in psychiatric patients. When a psychiatric disorder is diagnosed in a patient with symptoms of constipation, the patient may have developed both simultaneously; the presence of chronic constipation may have affected the patient’s behavior, or the psychiatric disorder precipitated fixation on bowel function symptoms.

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