| disease | Constipation (Surgery) |
| alias | Constipation |
Constipation refers to a decrease in bowel movements and/or dry, difficult-to-pass stools. Generally, the absence of bowel movements for more than two days indicates constipation. However, bowel habits can vary significantly among healthy individuals. For example, a survey of a group of healthy people showed that about 60% had one bowel movement per day, 30% had several per day, and 10% had one every few days. Therefore, determining whether constipation is present must be based on an individual's usual bowel habits and the presence of difficulty in passing stools.
bubble_chart Etiology
The process of defecation can be roughly divided into two steps: ① The propulsion of feces into the rectum: Under normal circumstances, the intestines undergo 3 to 4 mass peristalsis movements daily, rapidly moving feces into the rectum, expanding and stimulating the rectal mucosa, triggering the defecation reflex; ② The emptying of the rectum: When the rectum is filled with feces, the urge to defecate occurs. The act of defecation is regulated by the cerebral cortex and the lower centers in the lumbosacral spinal cord, involving rectal contraction, relaxation of the anal sphincter, and contraction of the abdominal and diaphragm muscles to expel feces through the anus. Mass peristalsis is often triggered by the gastrocolic reflex, hence defecation frequently occurs after meals.
There are many factors that can affect the defecation process and lead to constipation, including insufficient food intake, overly refined food lacking residue, pyloric or intestinal obstruction, decreased colonic tension, excessive and irregular spasmodic contractions of the sigmoid colon, as well as weakened contraction of the abdominal muscles, diaphragm, levator ani muscle, and/or intestinal smooth muscles.
Constipation can be classified based on its course or onset into acute and chronic constipation; based on the presence or absence of organic lesions into organic or functional constipation; and based on the site of fecal retention into colonic and rectal constipation. Colonic constipation refers to the overly slow movement of food residue in the colon, while rectal constipation means feces have already reached the rectum but remain there for too long without being expelled, also known as dyschezia. Additionally, it can be classified by etiology. Below, we mainly discuss organic and functional constipation.(1) Organic constipation
1. Rectal and anal lesions: Proctitis, hemorrhoids, anal fissure, perianal abscess and ulcers, tumor-induced cicatricial stenosis, etc.
2. Colonic lesions: Benign and malignant tumors, intestinal obstruction, intestinal strangulation, diverticulitis, specific (such as intestinal tuberculosis, amebic colitis) and non-specific inflammation (Crohn's disease, ulcerative colitis), intestinal adhesions, etc.
3. Muscle weakness: Weakened intestinal smooth muscles, levator ani muscle, diaphragm, or abdominal wall muscles due to aging, chronic pulmonary emphysema, severe malnutrition, multiple pregnancies, general debilitation, intestinal paralysis, etc., leading to difficulty in defecation.
4. Endocrine and metabolic diseases: Hyperparathyroidism causes intestinal muscle relaxation and reduced tension; hypothyroidism and anterior pituitary hypofunction weaken intestinal motility; diabetes insipidus with dehydration, diabetic neuropathy, scleroderma, etc., can all result in constipation.
5. Drugs and chemicals: Morphine and opium preparations; anticholinergic drugs, ganglionic blockers, and antidepressants; bismuth subcarbonate, diphenoxylate, and aluminum hydroxide, etc., can all cause constipation.
(2) Functional constipation
1. Simple constipation
(1) Insufficient food intake or overly refined food lacking fiber, reducing stimulation to colonic movement.
(2) Disrupted defecation habits due to psychological factors, changes in daily routine, long-distance travel, etc., leading to untimely defecation.
(3) Abuse of strong laxatives, reducing intestinal sensitivity and creating dependency on laxatives.
2. Irritable bowel syndrome: Constipation is one of its main manifestations, caused by motility disorders of the gastrointestinal smooth muscles.
bubble_chart Pathological Changes
Defecation is a complex physiological movement process involving multiple systems and influenced by various factors. Pathological changes in the digestive tract itself can cause constipation, and disorders in other systems can also lead to constipation by affecting the structure and function of the digestive tract.
Pathophysiology: It is generally believed that since the transit time of contents in the small intestine accounts for only a small portion of the total intestinal transit time (about 10%), the small intestine transit time does not play a significant role in the pathological process of constipation. Some studies have examined the small intestine transit time in patients with chronic constipation and found a grade I prolongation. In patients with hypothyroidism who experience constipation symptoms, treatment shortens the small intestine transit time.
Once the contents of the small intestine reach the colon, they serve as a culture medium for the colonic microbiota, allowing it to proliferate extensively. The microbiota can account for up to half of the solid matter in the colon and, together with other components, forms feces, which moves slowly toward the distal end at a speed of approximately 5 cm per hour.
In recent years, the importance of the enteric nervous plexus has gained attention and is referred to as the "gut brain." Beyond the well-known congenital megacolon, some authors have reported cases of idiopathic megacolon, megarectum, and even constipation patients without the appearance of megacolon, whose resected colon specimens show significant abnormalities in the myenteric plexus.
The absorptive function of the colonic mucosa and the size of the colonic lumen are also closely related to constipation. Absorption directly affects the consistency of intestinal contents, while the volume of the colonic lumen influences the movement of feces.
Normally, solid feces are stored in the sigmoid colon or even the descending colon. When the sigmoid colon or more proximal colon contracts, feces are propelled into the rectum, triggering the defecation reflex.
The rectum is usually empty at rest, and the rectal valves, along with the anorectal angle formed by the contraction of the puborectalis muscle, prevent feces from entering the rectal canal. A small number of people may have a small amount of feces in the rectum, but this does not induce the urge to defecate. When the proximal colon contracts and propels feces into the rectum in a certain volume and at a certain speed, two changes occur: First, the feces mechanically distend the rectum, increasing intraluminal pressure. Through the intrinsic rectal wall reflex, the internal anal sphincter relaxes, reducing tension and lowering anal canal pressure. This reflex is volume- and speed-dependent, meaning that within a certain range, the greater the volume and faster the speed of feces entering the rectum, the more pronounced and rapid the relaxation of the internal sphincter. Simultaneously, the pelvic floor muscles and external sphincter contract reflexively, stimulating defecation receptors in the pelvic floor. Impulses are sent to the cerebral cortex, generating the urge to defecate and causing the rectal smooth muscle to release its tonic contraction. This leads to relaxation of the pelvic floor muscles, puborectalis muscle, and external sphincter, lowering the pelvic floor into a funnel shape and increasing the anorectal angle while reducing anal canal pressure. At the same time, the rectum and distal colon contract reflexively, shortening the intestinal tract and increasing intraluminal pressure, allowing feces to be expelled smoothly. If the environment is not suitable for defecation, the pelvic floor muscles, puborectalis muscle, and external sphincter actively contract to prevent feces from entering the anal canal. Meanwhile, the rectum and colon adaptively relax, reducing rectal pressure and gradually dissipating the urge to defecate. If the urge is ignored, feces may return to the proximal colon via retrograde peristalsis. Any disruption in the above defecation reflex process can impair this reflex and lead to defecation disorders.
Among constipation patients, the lack of bowel movement sensation is one of the most common complaints. Some of these patients have an overly large rectal ampulla, making them unable to sense the stimulation from normal stool volume. However, more patients experience a gradual decline in rectal sensory function due to long-term neglect of the urge to defecate.
Internal sphincter relaxation dysfunction is one of the causes of outlet obstruction, with congenital megacolon being a typical example, characterized by tonic contraction of the distal rectum and the inability of the internal sphincter to relax reflexively. In cases of internal sphincter dysfunction caused by other factors, such as anal fissure patients, the resting pressure of the internal sphincter is elevated, but the anorectal inhibitory reflex remains intact.
If the striated muscles of the pelvic floor and the external sphincter fail to relax during defecation, the anorectal angle cannot widen, and the pelvic floor outlet cannot open, which is a common cause of outlet obstructive constipation. The disease etiology remains unclear to this day.
Additionally, certain conditions or diseases that significantly affect the increase in intra-abdominal pressure can also lead to reduced defecation dynamics, thereby impairing normal bowel movements.
bubble_chart Clinical Manifestations
Constipation itself is not an independent disease but rather a group of symptoms that can manifest in the digestive tract due to various diseases. Therefore, the clinical manifestations of patients with constipation symptoms can be understood from the following three aspects.
(1) Corresponding manifestations of the primary disease causing constipation: For example, large intestine cancer may present with mucus-bloody stools and masses; chronic intussusception may involve abdominal pain and lumps; anal fissure may cause painful defecation and bright red bloody stools; spinal tumors may exhibit neurological localization signs; hypothyroidism may present with cold intolerance and mucus edema, etc.
(2) Manifestations of defecation disorders:
1. Infrequent natural bowel movements, fewer than three times per week, with small stool volume and gradually worsening prolonged intervals between natural bowel movements.
2. Difficulty in defecation. This can be divided into two scenarios. One is dry and hard stools, resembling foxtail millet, which are difficult to pass; the other is stools that are not dry or hard but still difficult to pass. Some patients feel an obstructive sensation above the anus, which intensifies with increased straining during defecation, forcing the patient to exert excessive effort, even moaning loudly in extreme discomfort. Some female patients experience a sensation of stool pushing forward, feeling that the stool does not descend toward the anus but rather pushes toward the vagina; experienced individuals can insert a finger into the vagina and press against the posterior wall to facilitate stool passage. Some patients feel rectal fullness, sacrococcygeal pain, and incomplete defecation, and inserting a finger, paper roll, or soap bar into the anus can make defecation easier. These symptoms are collectively referred to as outlet obstruction syndrome. Among these patients, the majority (90.0%) have normal rectal-type bowel urges, frequent urges, and prolonged defecation times, averaging 23±16 minutes, with the longest lasting up to 2 hours per session.
(3) Associated symptoms. Apart from the characteristic manifestations of the aforementioned primary diseases, common associated symptoms in patients with no significant abnormalities found in routine examinations include abdominal distension and fullness, abdominal pain, thirst, nausea, and perineal distending pain. Most patients experience dysphoria, and some may also have a bitter taste in the mouth, headache, rashes, etc. A few patients exhibit neurotic tendencies, and some may even have suicidal inclinations.
From the perspective of Chinese medicine, the author believes that chronic constipation syndromes mainly include three patterns: insufficiency of body fluids, depression and stagnation of qi movement, and dual deficiency of the spleen and kidney.
(1) Pattern of fluid and humor insufficiency: Often caused by postpartum blood loss, excessive sweating or urination, or repeated damage to yin due to overindulgence in alcohol or spicy and hot foods, leading to dryness-heat in the intestines, or exposure to wind-heat-dryness-fire pathogens, or cold-damage disease Rebing damaging fluids, or constitutional yang exuberance, insufficient water intake, blood deficiency, and yin deficiency, all of which can result in insufficient body fluids in the intestines, losing their lubricating and smoothing function for stool, leading to constipation due to insufficient body fluids. The characteristics of this pattern include difficult and sluggish defecation, hard and lumpy stools, often dark brown or black in color, foul-smelling and small in volume, occurring every 3–5 days, accompanied by fetid mouth odor, lip sores, dry mouth and tongue, dizziness and headache, scanty and dark urine, irritability, vexing heat in the chest, palms, and soles, palpitations and insomnia, emaciation and anemia, reduced appetite, abdominal distension and fullness, a red tongue with scant moisture, and a thin and rapid pulse. The so-called yin deficiency, blood deficiency, fluid exhaustion, and yang constipation in traditional terms ultimately lead to depletion of fluids and humors, causing stool to harden due to insufficient body fluids, and thus can all be categorized under the pattern of fluid and humor insufficiency.
(2) Pattern of qi activity stagnation: Often caused by emotional distress, grief, or worry, neglecting regular bowel movements, prolonged inactivity or bed rest, or insufficient food intake, leading to depression and stagnation of qi movement, inability to disperse and circulate, impaired conduction, and retention of waste. Patients with hemorrhoids or anal fissures who habitually withhold bowel movements, resulting in abnormal descending and discharge, are also common causes of this pattern. The hallmark of this pattern is "internal stagnation of qi preventing the passage of matter." Although the stools are not dry or hard, defecation is difficult, and despite feeling abdominal distension and fullness and anal heaviness, squatting yields no stool, incomplete evacuation, or persistent heaviness after defecation. Associated symptoms include chest and hypochondriac stuffiness and fullness, reduced food intake, heaviness of the head and mental fog, fatigue and bodily heaviness, abdominal distension and fullness with borborygmus, excessive flatulence, belching, a thin and greasy tongue coating, and a wiry and large pulse. Impaired lung purification, stomach disharmony, liver failing to act freely, and spleen failing to transform and transport can all lead to depression and stagnation of qi movement. Dampness encumbering the middle energizer or wind affecting the large intestine can also impair dispersion and conduction, slowing transit and causing constipation. The so-called qi constipation, wind constipation, and dampness constipation in traditional terms mostly belong to this pattern.
(3) Spleen-Kidney Dual Deficiency Pattern: Often caused by prolonged use of purgatives, bitter-cold drugs damaging the spleen, excessive sexual activity leading to essence depletion and kidney deficiency, resulting in spleen deficiency with weakened qi, impaired transmission and propulsion, and kidney deficiency with essence exhaustion failing to transform body fluids and warm-moisten the intestines, leading to difficulty in bowel movement despite the stool being ready to pass. Its characteristics include stool retention in the intestines without the urge to defecate, or straining with lack of strength despite the urge, extreme difficulty in passing stool, sweating and shortness of breath during defecation, and exhaustion afterward. Accompanied by dizziness, tinnitus, panting and palpitations, soreness in the lower back and back pain, abdominal distension and fullness with a preference for warmth, clear and copious urine, anorexia and reduced food intake, long-term reliance on purgatives for bowel movements, and failure to defecate for several days without purgatives. Other signs include a pale tongue with thick greasy coating and a weak pulse.
bubble_chart Auxiliary Examination
(1) Physical Examination:
1. A comprehensive and systematic physical examination must be conducted in accordance with the requirements of diagnostics. Constipation should not be treated carelessly as a minor issue, lest important pathological changes such as fistula disease be overlooked. At the same time, diagnosing constipation should not be regarded as overly challenging, leading to the excessive use of complex examination methods while neglecting routine checks, which may delay the detection of otherwise easily identifiable conditions. However, for most chronic constipation patients, due to the long duration of the condition and numerous past examinations, abdominal signs are often not very obvious.
2. Anorectal Examination:
(1) Inspection: Check for anal fissure, fistula openings, prolapsed hemorrhoids, perianal inflammation, blood traces, etc. Ask the patient to simulate defecation; in cases of perineal descent, the pelvic floor will visibly protrude downward with the anus as the center. Then instruct the patient to contract the anus; those with severe nerve damage to the pelvic floor will exhibit weakened or absent contraction ability.
(2) Digital Rectal Examination: Avoid roughness. Ensure the examining finger and the patient's anus are well-lubricated to make the examination painless and minimize interference with the physiological state of the anorectal region. A normal anal canal can accommodate one finger with moderate tension. When the patient simulates defecation, the external sphincter and pelvic floor muscles should relax noticeably. Increased anal canal tension may indicate nearby irritative sexually transmitted disease changes. If the anal canal cannot accommodate one finger, organic stenosis is likely, often seen in low-position tumors, post-anal surgery, or scar formation from improper sclerotherapy. In some patients, hardened fecal masses may be palpated in the rectal ampulla. A large amount of retained feces in the rectum without the urge to defecate suggests rectal inertia. Patients with rectocele may exhibit a pouch-like weak area above the sphincter and below the pubic symphysis during defecation. Those with rectal intussusception may present with a lax rectal wall, a sensation of accumulated mucus during digital examination, or occasionally palpable intussuscepted bowel walls. Patients with pelvic floor dyssynergia syndrome show no relaxation of the pelvic floor muscles, puborectalis muscle, or external sphincter during defecation; severe cases may feature a markedly hypertrophic, thickened, stiff, and less mobile anorectal ring, increased anal canal tension, and significant pain. Using the examining index finger to press various directions of the rectal ampulla can assess pelvic floor sensory function (i.e., rectal sensory function), providing a rough estimate of sensory impairment severity.
(3) Anoscopy: Internal hemorrhoids and low rectal masses can be visualized. If rectal mucosa shows edema, erosion, or other changes not easily explained by general inflammation, consider the possibility of rectal intussusception. Unexplained blood traces, especially old ones, should raise suspicion of proximal tumors.
(2) Auxiliary Examinations:
1. Stool Examination: The examiner should visually inspect a single bowel movement from the patient, roughly estimate its weight, and observe its physical characteristics. Dry, hard, pellet-like stools suggest irritable bowel syndrome. Routine stool tests and occult blood tests should also be performed.
2. Blood Generation and Transformation Tests: Focus on endocrine and metabolic factors that may cause constipation. In recent years, the relationship between gastrointestinal hormones and constipation has drawn attention. Foreign scholars have conducted some research, but conclusions remain unclear, and domestic studies in this area are still limited.
3. Barium Enema: One of the primary methods for diagnosing organic sexually transmitted diseases of the colon. It can detect redundant colon or colonic dilation. If the rectosigmoid width exceeds 6.5 cm at the pelvic inlet on a lateral view, it is considered abnormal.
4. Endoscopy: The main purpose is to rule out tumor-related sexually transmitted diseases. Long-term enema users, especially those using soapy water, may exhibit colonic mucosal edema and obscured vascular patterns. Chronic users of anthraquinone laxatives may show mucosal melanosis, ranging from light brown to black.
5. Colonic Transit Function Test: This involves ingesting radiopaque markers and taking timed abdominal X-rays to track their progress through the colon. It is a method to assess the speed of colonic content movement and identify sites of obstruction.
6. Anorectal manometry: This involves using a pressure measurement device to examine the functional status of the internal and external sphincters, pelvic floor, and rectum, as well as their coordination. It is highly significant in determining whether constipation is related to functional abnormalities in these structures.
7. Pelvic Floor Electromyography (EMG): This electrophysiological technique is used to assess the functional status of the pelvic floor muscles, puborectalis muscle, external sphincter, and other striated muscles, as well as the functional state of their innervating nerves. Due to the high technical demands of this procedure and the difficulty in interpreting results, it is currently primarily used to detect abnormal electrical discharges in the pelvic floor striated muscles during simulated defecation. When needle electrodes are employed, the invasive nature of the test may trigger protective reflexes, leading to false positives. This risk is particularly pronounced when multiple needle electrodes are used simultaneously, and inexperienced operators may misinterpret the findings. Caution is advised.
8. Defecography: After injecting barium contrast into the rectum and colon (orally administered barium may also be used to visualize the small intestine), the patient sits on an X-ray-transparent commode. Multiple X-ray images or video recordings are taken during defecation to observe imaging changes in the anal canal and rectum. The examiner should personally review the images and integrate them with clinical data and other test results for a comprehensive assessment, rather than relying solely on imaging findings for diagnosis.
9. Histological Examination: If congenital megacolon is suspected, a biopsy should be performed. Traditionally, samples were taken 2–3 cm above the dentate line, but some experts recommend sampling 1–1.5 cm above the dentate line instead, as higher sampling may miss cases of "ultra-short segment Hirschsprung’s disease."
Diagnosing constipation is not difficult based on reduced bowel movements and dry, hard stools that are difficult to pass. However, to determine the cause of constipation, in addition to carefully inquiring about medical history, symptoms, and conducting a comprehensive physical examination, the following tests are also required.
(1) Stool examination: Carefully observe the shape, size, consistency, presence of pus, blood, or mucus in the stool. Stool routine and occult blood tests are routine examinations.
(2) Digital rectal examination: Helps detect rectal cancer, hemorrhoids, stenosis, hard fecal impaction, external compression, anal sphincter spasm, or relaxation.
(3) Endoscopic examinations such as proctoscopy, sigmoidoscopy, and colonoscopy: These allow direct observation of the intestinal mucosa for any lesions and enable biopsy to determine the nature of the lesions.
(4) Gastrointestinal X-ray examination: Barium meal examination provides reference value for understanding gastrointestinal motility. Normally, barium reaches the splenic flexure of the colon within 12–18 hours and should be completely expelled from the colon within 24–72 hours. In constipation, delayed emptying may occur. Barium enema, especially low-tension double-contrast colonography, may help identify the disease cause of constipation.
(5) Special examinations: Swallowing a certain number of X-ray-opaque plastic tube fragments as markers and taking timed abdominal X-rays can reveal the transit speed and distribution of the markers in the gastrointestinal tract, distinguishing between rectal constipation and colonic constipation. Defecography is a combined dynamic and static examination of defecation, aiding in the diagnosis of functional constipation. Additionally, there are direct or colonic manometry, anorectal electromyography, and transanal balloon expansion tests.
bubble_chart Treatment Measures
Emphasize treatment based on the medical records after a clear diagnosis. Treatment without a clear diagnosis is a blind symptomatic approach, which carries the risk of missing important lesions such as fistula disease, delaying the condition, or even leading to incorrect treatment.
Some have proposed that the goals of treating chronic constipation are: ① restoring normal bowel movement frequency and stool consistency; ② relieving discomfort caused by constipation; ③ maintaining regular bowel movements without artificial assistance; and ④ alleviating the underlying conditions that may cause constipation symptoms. Achieving these goals is not easy and requires doctors to be familiar with the physiology of defecation, deeply understand the disease causes and pathophysiology of the patient's constipation, correctly apply various treatment methods, and have the patient's active cooperation. However, the key remains accurate diagnosis.
(1) Treatment of the underlying disease: For identified underlying conditions, after a clear diagnosis, appropriate measures should be taken for active treatment. For example, anal fissures can be treated with local anesthesia and anal dilation or lateral internal sphincterotomy; colon tumors may require radical or palliative resection; if constipation is caused by medication, the drug should be discontinued or replaced with one that does not cause constipation; for constipation due to mental illness or endocrine and metabolic disorders, corresponding treatments should be administered to promptly eliminate the impact of the underlying disease on intestinal function.
(2) General treatment: For cases where the underlying disease is difficult to correct temporarily or no obvious primary factors have been identified, the following general measures are beneficial for most constipation patients.
1. Correcting poor dietary habits: Increase intake of high-fiber foods and develop the habit of drinking more water. Dietary fiber can soften stools, increase stool volume, and stimulate colonic motility, speeding up colonic transit. Regularly taking a small amount of wheat bran orally is an effective and inexpensive therapy for constipation patients, but this method is not suitable for those with organic intestinal stenosis. Daily water intake should reach 3,000 ml, and excessive consumption of tea or coffee bean-containing beverages should be avoided to prevent excessive diuresis. With the above treatments, constipation caused by dietary and lifestyle changes can often be quickly relieved.
2. Correcting poor defecation habits: Ignoring the urge to defecate is a common phenomenon among female constipation patients, with statistics showing it as high as 33%. Many are too busy with household chores in the morning or rushing to work to use the toilet, while others suppress the urge due to workplace constraints. Frequently ignoring the urge can disrupt normal defecation reflexes, leading to constipation. Reading books or newspapers while sitting on the toilet is another poor defecation habit, hindering the continuity of the defecation reflex. For those unaccustomed to sitting toilets, squatting may be more beneficial, as it increases the anorectal angle, facilitating stool passage. For those habitually relying on laxatives, their use should be stopped immediately, and normal defecation habits should be restored under medical guidance.
3. Developing good lifestyle habits: Maintaining a regular daily routine, actively participating in physical activities, and staying optimistic can also help improve digestive function.
(3) Drug treatment: Many drugs can be used to treat constipation, but most are unsuitable for chronic constipation patients or long-term use. Currently, the misuse of laxatives is widespread, leading to iatrogenic constipation, and their selection should be approached with caution. Common laxatives fall into the following categories.
1. Stimulant laxatives: These work by stimulating the colonic mucosa, myenteric plexus, and smooth muscles to increase intestinal motility and mucus secretion. Common examples include Rhubarb Rhizoma, senna leaves, phenolphthalein, and castor oil.
Rhubarb Rhizoma and Senna Leaf contain anthraquinones, which are hydrolyzed by colonic bacteria into active components to take effect, acting only on the colon or distal ileum. Rhubarb Rhizoma produces slightly soft stools 6–8 hours after oral administration; Senna Leaf induces diarrhea 8–10 hours after ingestion. If taken in large doses, it may cause abdominal pain and pelvic congestion due to excessive irritation, hence it is contraindicated during menstruation and pregnancy. Anthraquinones can cause "melanosis coli," where melanin deposits in the colonic mucosa, often occurring after 4–13 months of use and disappearing within 3–6 months after discontinuation, generally without causing long-term lesions. Phenolphthalein forms soluble sodium salts upon encountering alkaline intestinal fluids after oral administration, mildly irritating the colon and producing soft stools 4–8 hours after ingestion. Part of it is excreted via bile and reabsorbed in the intestines, forming an enterohepatic cycle, so a single dose can maintain its effect for 3–4 days. Castor Oil is hydrolyzed in the small intestine after oral administration, releasing sodium ricinoleate, which stimulates active secretion in the small intestine, reduces sugar absorption, and promotes intestinal motility, resulting in loose stools 3–5 hours after ingestion.
Stimulant laxatives can cause severe colicky pain, and long-term use may lead to water-electrolyte imbalances and acid-base disturbances. After years of regular use, they may induce "laxative colon," which is often misdiagnosed as intractable constipation, leading to the administration of more laxatives or even inappropriate treatments.
2. Mechanical Laxatives: These work by increasing fecal volume or altering fecal composition to enhance colonic propulsion. They can be further classified into the following categories:
(1) Saline Laxatives: Examples include magnesium sulfate and sodium sulfate. These are poorly absorbed after oral administration, raising the osmotic pressure in the intestinal lumen and preventing water absorption, thereby increasing intestinal content volume and stimulating peristalsis. Their effects are rapid, occurring within 0.5–3 hours after oral intake or 5–15 minutes after rectal administration. They are suitable for acute constipation, while enemas are often used for fecal impaction. Long-term use is not recommended, as severe diarrhea may cause dehydration.
(2) Bulk-Forming Laxatives: These contain cellulose, which absorbs water to form a soft gel, facilitating stool passage and stimulating peristalsis. Effects occur within 1 to several days after ingestion, with no systemic effects, making them suitable for long-term use—especially in cases of low-fiber diets, pregnancy, or withdrawal from stimulant laxatives. Examples include wheat bran, corn bran, konjac starch, agar, methylcellulose, and Plantain Seed preparations. Adequate water intake is essential when using these agents. Caution is advised in cases of intestinal stenosis due to the risk of obstruction.
(3) Stool Softeners: These are surfactants that facilitate the mixing of fats and water in stool and increase intestinal secretion, such as sodium (calcium) docusate. They are not absorbed but may enhance the absorption of other substances, potentially contributing to hepatotoxicity. They are suitable only for short-term use (1–2 weeks) and are not ideal for chronic constipation.
(4) Lubricant Laxatives: Examples include mineral oil. These are not digested or absorbed in the intestines, coating stool to ease passage while inhibiting colonic water absorption, thus lubricating the bowel and softening stool. Effects occur 6–8 hours after oral administration. Long-term use may impair the absorption of fat-soluble vitamins. They should not be used with surfactants to avoid increased mineral oil absorption. Prolonged use may also lead to anal leakage, causing cutaneous pruritus. They are only suitable for short-term use and not for chronic constipation.
(5) Osmotic Laxatives: By increasing intraluminal osmotic pressure, they stimulate peristalsis. Glycerin, when administered rectally, induces defecation within minutes due to its hyperosmotic effect on the rectal wall, also providing lubrication. Lactulose is metabolized by colonic bacteria into low-molecular-weight acids, lowering colonic pH and increasing motility.
(6) Other Laxatives: Previously used laxatives such as calomel, aloes, lobedleaf pharbitis seed, croton fruit, and sulfur are no longer in use.
When managing constipation, it is essential to understand the mechanisms of these laxatives and use them appropriately. Generally, bulk-forming laxatives are preferred for chronic constipation, with stimulant laxatives reserved for necessity. Acute constipation may be treated with low-dose saline laxatives, stimulant laxatives, or lubricants, but not for more than one week. If constipation persists beyond this period, further evaluation is needed. Patients abusing stimulant laxatives long-term must gradually discontinue them while adding bulk-forming laxatives. In such cases, bran preparations with increased water intake can help restore regular bowel movements, supplemented occasionally with mild laxatives for a smooth transition.
Many patients, either self-medicating or following medical advice, take laxatives continuously. However, after a single dose empties the colon, it takes 3–4 days for the colon to refill, making continuous use inappropriate. Since most oral laxatives take 6–8 hours to act, taking them at bedtime is more physiologically sound, allowing defecation the next morning or after breakfast.
(4) Enema: The main indications are preoperative bowel preparation, fecal impaction, and acute constipation. Warm saline is more suitable as it causes less irritation to the intestines. Soapy water should be avoided due to its strong irritation to the colonic mucosa. Additionally, frequent enemas can lead to dependence, which should be noted.
(5) Surgical treatment: The main indications for surgical treatment are constipation caused by organic or functional sexually transmitted diseases of the colon, rectum, and anal canal.
1. Colonic obstruction: Since conventional examination methods can easily identify such lesions, corresponding treatment measures can be taken promptly to restore colonic patency and eliminate constipation symptoms.
2. Rectal-anal outlet obstruction:
⑴ Anal stenosis, anal fissure, and hemorrhoids can be treated with appropriate surgical interventions, with care taken to protect anal canal tissues to avoid postoperative stenosis.
⑵ Rectal intussusception.
⑶ Rectocele: This is very common in women, but only some patients experience constipation symptoms, and there is no clear parallel relationship between the depth of the rectocele and the severity of defecation difficulties. This suggests that identifying a rectocele does not equate to discovering the true disease cause of constipation. According to the author's research, rectocele is merely one manifestation of pelvic floor relaxation among many clinical presentations, and a significant number of patients with slow-transit constipation also exhibit obvious rectocele. Only after repeated and thorough examinations—excluding factors such as slow intestinal transit, dysfunction of the internal and external sphincters, pelvic floor muscle abnormalities, rectal intussusception, and laxative abuse—followed by 1–3 months of strict conservative treatment, can it be determined whether rectocele is the primary cause of outlet obstruction symptoms. If conservative treatment fails to relieve symptoms, rectocele repair surgery may achieve the desired results. Rushing into surgical treatment based solely on certain examinations is unlikely to yield reliable long-term outcomes.
(4) Spastic pelvic floor syndrome and puborectalis syndrome: Both are syndromes caused by the inability of the pelvic floor muscles (striated muscles) to relax during defecation, or even contracting instead, thereby blocking the pelvic floor outlet and leading to difficulty in defecation. Many issues regarding the disease cause, diagnosis, and treatment of these two syndromes remain to be further explored. Previously, it was believed that the main difference between the two syndromes was the hypertrophy of the puborectalis muscle in the latter. Therefore, partial resection or transection of the puborectalis muscle was once used to treat such conditions, but the long-term outcomes were unsatisfactory. Currently, biofeedback therapy is more commonly adopted to train patients to relax their pelvic floor muscles during defecation. Persistent long-term training has yielded better results. After studying the above two syndromes, the author suggests that the cause of such diseases may be related to underlying congenital abnormalities. The two syndromes may represent different stages of the same disease. Their common clinical feature is the dysfunction of reflexive relaxation of the striated muscles of the pelvic floor during defecation, leading to abnormal overall contraction of the pelvic floor muscles and external sphincter, while no significant abnormalities are observed during rest or pelvic floor contraction. Therefore, it is proposed to uniformly rename them as "unrelaxed pelvic floor syndrome." To date, no pathological changes have been anatomically, physiologically, or histologically confirmed to occur solely in the puborectalis muscle in the latter syndrome. The author conducted synchronous electromyography measurements of the puborectalis muscle, pubococcygeus muscle, and external sphincter in multiple patients with such conditions, all confirming synchronous abnormal discharges. Thus, the term "puborectalis syndrome" is deemed inappropriate and should be abandoned. Isolated resection or transection of the puborectalis muscle cannot alter the pathophysiological mechanism causing the overall abnormal contraction of the pelvic floor and external sphincter. Moreover, the damage caused by surgery makes it unsuitable for treating such patients, although some young patients experienced relief from constipation symptoms. The author believes that biofeedback therapy should be the first-line treatment for such patients, combined with other measures to alleviate defecation difficulties, such as a high-fiber diet, to restore normal defecation reflexes as much as possible. The following criteria may be considered as surgical indications: ① Digital rectal examination reveals significant hypertrophy of the pelvic floor muscles causing anal canal stenosis, with posterior rectal pouch-like protrusion; ② Anorectal manometry shows an anal functional length exceeding 5–6 cm, while the internal sphincter functions normally; ③ Pelvic floor electromyography detects pathological polyphasic waves in the striated muscles of the pelvic floor exceeding the upper limit of normal values, with confirmed abnormal discharges during simulated defecation; ④ Intestinal transit function tests show significant decompensation of expulsion function, i.e., markers retained in the rectal ampulla; ⑤ Long-term (at least 3 months) strict conservative treatment has failed, and the patient is in extreme distress. Since posterior muscle partial resection can shorten the anal canal length and reduce defecation resistance, it may serve as a palliative therapy for the late stage (third stage) of this syndrome, provided the procedure is well-designed and meticulously performed. The extent of striated muscle resection should ensure the postoperative anal functional length is no less than 3 cm.
3. Visceral neuropathy:
(1) Congenital megacolon: For patients with short-segment congenital megacolon, forceful anal dilation or anorectal smooth muscle resection can be employed. Literature reports indicate that this method yields good therapeutic outcomes and serves both diagnostic and treatment purposes. Key surgical points: Posterior to the anal canal, a strip of internal sphincter and rectal smooth muscle approximately 1 cm wide and 6–10 cm long is excised submucosally, followed by wound suturing.
(2) Idiopathic megacolon: Its clinical and radiographic manifestations resemble those of "short-segment megacolon." The disease cause may be acquired, but congenital factors cannot be ruled out. Its clinical features include extremely long intervals between bowel movements, the passage of large amounts of dry, hard stools accompanied by pain during defecation. However, the patient's general condition is usually good. Routine examination may reveal palpable fecal masses in the abdomen and large amounts of dry, hard stool in the rectum. Water-soluble contrast enema shows significant rectal dilation. The key points for differentiation from short-segment megacolon are: ① The anorectal inhibitory reflex is present (note: due to rectal dilation, the balloon for rectal distension must be sufficiently large to contact the intestinal wall to avoid false negatives); ② No abnormalities in the myenteric plexus are observed, and during intestinal transit function tests, markers are retained in the rectum. Treatment primarily involves enemas and maintaining rectal emptiness, with oral magnesium sulfate administered as needed. For cases unresponsive to conservative treatment, partial internal sphincter resection, anorectal smooth muscle resection, or even Duhamel's procedure may be performed.
(3) Colonic inertia: Also known as idiopathic slow-transit constipation, its surgical treatment remains a challenging issue. Colonic inertia refers to a normal-appearing colon with significantly prolonged whole-gut transit time. Although many authors report good outcomes with colectomy for this type of constipation, surgeons are generally reluctant to remove a morphologically normal colon. Reports suggest that such constipation patients exhibit significant visceral nerve abnormalities, but due to the difficulty in preoperatively determining the extent of these abnormalities, the appropriate length of bowel resection remains uncertain. According to foreign authors' experience, resection of the affected colonic segment can correct constipation. For example, if colonic inertia occurs in the left colon, left hemicolectomy can relieve constipation; if it involves the entire colon, total colectomy with ileorectal anastomosis is required.
(6) Chinese medicine treatment: Chinese medicine has always emphasized a holistic approach to treating constipation, targeting the disease cause, regulating diet, lifestyle, and emotions, and adhering to the principles of "preserving stomach qi and body fluids" while using medications appropriately. It opposes the misuse of purgatives, which can deplete qi and fluids. Zhang Zhongjing repeatedly emphasized in the "Treatise on Cold Damage Diseases" that not all cases of Yangming disease with severe symptoms are suitable for cold purgation. If intestinal body fluids are depleted, even if the stool is hard, purgation should not be used; instead, external guidance or moistening purgation is preferable. He cautioned, "In Yangming disease with spontaneous sweating, if sweating is induced and urination is free, this indicates internal exhaustion of body fluids—even if the stool is hard, purgation must not be used." However, many practitioners still treat constipation superficially, prescribing Chengqi Decoction for purgation without understanding that "Chengqi is intended to expel pathogens, not solely to remove fecal impaction." Purgation is only appropriate when harmful substances such as pathogenic heat, retained food, static blood, phlegm-fluid retention, or food/drug poisoning are present, allowing the expulsion of pathogens through downward drainage. Chronic constipation results from depleted body fluids, stagnant qi movement, and spleen-kidney deficiency; thus, purgation is entirely unnecessary.
1. Adjusting diet and daily routine is the fundamental treatment for constipation. Chinese medicine places great emphasis on dietary therapeutics for constipation, advocating that once the symptoms of constipation are relieved, one should rely on "grains, meat, fruits, and vegetables, preserving health with food." Commonly used foods include: black sesame, walnut kernel, hemp fruit, Platycladi Seed, pine nut kernel, Bush Cherry Seed, Bitter Apricot Seed, root juice of earth melon, sunflower seeds, Donkey-hide Gelatin, honey, milk, cow butter, sheep butter, etc. These foods are smooth in nature, rich in nutrients, and particularly suitable for constipation in the elderly, postpartum women, children, and patients. The vast majority of habitual constipation cases can be resolved by improving diet and daily routines, increasing physical activity, and correcting reliance on laxatives for bowel movements. Only a very few patients require medication for treatment.
2. The greatest characteristic of Chinese medicine in treating chronic constipation is the dialectical use of medication, opposing the simplistic approach of purging upon seeing constipation. Only in this way can treatment be flexible and appropriate, without leaving behind any sequelae. Commonly used treatments include:
(1) **Replenishing Humor to Promote Defecation**: This method involves nourishing yin and blood to replenish bodily fluids and facilitate bowel movements. *Yizong Bidu* states: "In the elderly, dryness of body fluids, postpartum blood loss in women, excessive sweating, diuresis, or unrecovered blood and qi after illness can all lead to constipation. The method should focus on tonifying and nourishing qi and blood, allowing body fluids to regenerate and naturally restore bowel movements." It further notes: "Misusing purgatives like Nitre and Rhubarb for such constipation often leads to dire consequences, while Croton Fruit and Lobedleaf Pharbitis Seed cause even swifter harm. Instead, Eight Precious Ingredients Decoction should be used with additions like Cultivated Purple Perilla Fruit, Red Tangerine Exocarp, Bitter Apricot Seed, and Cistanche, doubling the dosage of Chinese Angelica." The author primarily employs **Four Ingredients Decoction** supplemented with **Desertliving Cistanche, Fleeceflower, and Donkey-hide Gelatin** for this method. For **yin deficiency**, add **Ligustrum Fruit, Songaria Cynomorium Herb, and Asparagus Root**; for **blood deficiency**, add **Black Sesame and Mulberry Fruit**; for intestinal dryness and depleted fluids, add **Hemp Fruit, Platycladi Seed, and Honey**; for **qi stagnation**, add **Submature Bitter Orange and Magnolia Bark**; and for **blood deficiency with heat**, add **Sanguisorba Root, Japanese Pagodatree Pod, and Skullcap Root**. Many cases treated this way have achieved satisfactory results.
(2) **Regulating Qi to Relieve Constipation**: This method involves smoothing qi flow, resolving stagnation, ascending clarity, and descending turbidity—opening the upper orifices and unblocking the lower ones, akin to "lifting the pot and removing the lid." It is suitable for **constipation due to depression and stagnation of qi movement**. Earlier practitioners often used **Six Milling Decoction** (Areca Seed, Aquilaria, Aucklandia Root, Lindera, Submature Bitter Orange, Rhubarb Rhizome) as the main formula. However, Rhubarb Rhizome in this formula damages body fluids, worsening constipation. Therefore, *Taiping Huimin Heji Jufang* recommends **Perilla Fruit Qi-Descending Decoction** (Cultivated Purple Perilla Fruit, Pinellia, Peucedanum, Magnolia Bark, Red Tangerine Exocarp, Chinese Angelica, Liquorice Root, Cassia Bark, or Aquilaria) as the primary formula. Additional ingredients like **Radish Seed, Trichosanthes Fruit, Submature Bitter Orange, and Bitter Apricot Seed** may be included.
(3) **Strengthening the Spleen and Tonifying the Kidneys**: This method involves tonifying and replenishing the spleen and kidneys to address the root cause of constipation. The kidneys govern the **five kinds of fluids**, while the spleen governs the dispersion of essence. The kidneys, located below, dominate qi transformation, while the spleen, positioned centrally, governs transportation. When body fluids are abundant and qi transformation functions smoothly, bowel movements remain regular. If the spleen fails in distribution or the kidneys lack warmth and moisture, severe constipation arises. Thus, strengthening the spleen and tonifying the kidneys is a fundamental approach for treating stubborn constipation. For **qi deficiency constipation** due to **spleen deficiency and insufficient middle qi**, which weakens the large intestine's ability to guide qi, **Middle-Tonifying Qi-Replenishing Decoction** can be modified by adding **Tail of Chinese Angelica**, **Desertliving Cistanche**, and **Chinese Clematis Root**. For **kidney yin deficiency** with depleted fluids, **Six-Ingredient Rehmannia Decoction** can be supplemented with **Ophiopogon Tuber, Achyranthes Root, Desertliving Cistanche, and Black Sesame**. For **kidney yang deficiency** impairing qi transformation, **Fluid-Replenishing Decoction** combined with **Pinellia and Sulfur Pill** may be used. The author often employs a self-formulated **"Yunchang Tongbian Decoction"** (Intestine-Moving Constipation-Relieving Decoction) for stubborn constipation. The formula includes: - **Desertliving Cistanche 15g** - **Achyranthes Root 10g** - **Prepared Rehmannia Root, Chinese Angelica, White Atractylodes Rhizome 15g each** - **Chinese Clematis Root 10g** This formula simultaneously tonifies the spleen and kidneys without being overly drying or cold, enhancing their roles in intestinal movement and promoting bowel movements—hence its name. It is particularly effective for **constipation due to spleen-kidney dual deficiency** in the elderly, chronic illness, postpartum recovery, or prolonged laxative use. For cases with **mixed deficiency and excess**, where **abdominal distension and severe constipation** are present, add **Radish Seed and Magnolia Bark 10g each**. For **spleen-kidney yang deficiency** with **cold abdomen and constipation**, add **Leek Seed and Common Fenugreek Seed 10g each**.
In recent years, **Hu Bohu** has achieved good results using **Cistanche Constipation-Relieving Oral Liquid** to treat constipation, confirming its efficacy for **chronic deficiency-type constipation** and **habitual constipation**. After taking the medication, patients pass formed, soft stools. Its laxative effect primarily stems from **enriching yin, tonifying the kidneys, and moistening the intestines to relieve constipation**.
