Symptoms include chronic constipation. There can be fecal incontinence and paradoxical or overflow diarrhea (encopresis) as liquid stool passes around the obstruction. Complications may include necrosis and ulcers of the rectal tissue. Abdominal pain and bloating could also be present depending on the severity of the condition. Loss of appetite can also occur.

A fecal impaction is a solid, immobile bulk of human feces that can develop in the rectum as a result of chronic constipation. A related term is fecal loading which refers to a large volume of stool in the rectum of any consistency.

Depending on the level of obstruction, bowel obstruction can present with abdominal pain, swollen abdomen, abdominal distension, vomiting, fecal vomiting, and constipation.

Bowel obstruction may be complicated by dehydration and electrolyte abnormalities due to vomiting; respiratory compromise from pressure on the diaphragm by a distended abdomen, or aspiration of vomitus; bowel ischemia or perforation from prolonged distension or pressure from a foreign body.

In small bowel obstruction, the pain tends to be colicky (cramping and intermittent) in nature, with spasms lasting a few minutes. The pain tends to be central and mid-abdominal. Vomiting may occur before constipation.

In large bowel obstruction, the pain is felt lower in the abdomen and the spasms last longer. Constipation occurs earlier and vomiting may be less prominent. Proximal obstruction of the large bowel may present as small bowel obstruction.

Gastric impactions are relatively rare, and occur when food is not cleared at the appropriate rate. It is most commonly associated with ingestion of foods that swell after eating or feeds that are coarse (bedding or poor quality roughage), poor dental care, poor mastication, inadequate drinking, ingestion of a foreign object, and alterations in the normal function of the stomach. Persimmons, which form a sticky gel in the stomach, and haylage, have both been associated with it, as has wheat, barley, mesquite beans, and beet pulp. Horses usually show signs of mild colic that is chronic, unresponsive to analgesics, and may include signs such as dysphagia, ptyalism, bruxism, fever, and lethargy, although severe colic signs may occur. Signs of shock may be seen if gastric rupture has occurred. Usually, the impaction must be quite large before it presents symptoms, and may be diagnosed via gastroscopy or ultrasound, although rectal examinations are unhelpful. Persimmon impaction is treated with infusions of Coca-Cola. Other gastric impactions are often resolves with enteral fluids. Quick treatment generally produces a favorable prognosis.

Uterine tears often occur a few days post parturition. They can lead to peritonitis and require surgical intervention to fix. Uterine torsions can occur in the third trimester, and while some cases may be corrected if the horse in anesthetized and rolled, others require surgical correction.

Fecal vomiting, also called feculent vomiting and stercoraceous vomiting is a kind of vomiting wherein the material vomited is of fecal origin. It is a common symptom of gastrojejunocolic fistula and intestinal obstruction in the ileum. Fecal vomiting is often accompanied by an odor of feces on the breath and other gastrointestinal symptoms, including abdominal pain, abdominal distension, dehydration, and diarrhea. In severe cases of bowel obstruction or constipation (such as those related to Clozapine-treatment) fecal vomiting has been identified as a cause of death.

Fecal vomiting occurs when the bowel is obstructed for some reason, and intestinal contents cannot move normally. Peristaltic waves occur in an attempt to decompress the intestine, and the strong contractions of the intestinal muscles push the contents backwards through the pyloric sphincter into the stomach, where they are then vomited.

Fecal vomiting can also occur in cats.

Fecal vomiting does not include vomiting of the proximal small intestine contents, which commonly occurs during vomiting.

Bowel obstruction, also known as intestinal obstruction, is a mechanical or functional obstruction of the intestines which prevents the normal movement of the products of digestion. Either the small bowel or large bowel may be affected. Signs and symptoms include abdominal pain, vomiting, bloating, and not passing gas. Mechanical obstruction is the cause of about 5 to 15% of cases of severe abdominal pain of sudden onset requiring admission to hospital.

Causes of bowel obstruction include adhesions, hernias, volvulus, endometriosis, inflammatory bowel disease, appendicitis, tumors, diverticulitis, ischemic bowel, tuberculosis, and intussusception. Small bowel obstructions are most often due to adhesions and hernias while large bowel obstructions are most often due to tumors and volvulus. The diagnosis may be made on plain X-rays; however, CT scan is more accurate. Ultrasound or MRI may help in the diagnosis of children or pregnant women.

The condition may be treated conservatively or with surgery. Typically intravenous fluids are given, a tube is placed through the nose into the stomach to decompress the intestines, and pain medications are given. Antibiotics are often given. In small bowel obstruction about 25% require surgery. Complications may include sepsis, bowel ischemia, and bowel perforation.

About 3.2 million cases of or bowel obstruction occurred in 2015 which resulted in 264,000 deaths. Both sexes are equally affected and the condition can occur at any age. Bowel obstruction has been documented throughout history with cases detailed in the Ebers Papyrus of 1550 BC and by Hippocrates.

Constipation is a symptom, not a disease. Most commonly, constipation is thought of as infrequent bowel movements, usually less than 3 stools per week. However, people may have other complaints as well including:

- Straining with bowel movements

- Excessive time needed to pass a bowel movement

- Hard stools

- Pain with bowel movements secondary to straining

- Abdominal pain

- Abdominal bloating.

- the sensation of incomplete bowel evacuation.

The Rome Criteria are a set of symptoms that help standardize the diagnosis of constipation in various age groups. These criteria help physicians to better define constipation in a standardized manner.

External signs and symptoms are constipation of very long duration, abdominal bloating, abdominal tenderness and tympany, abdominal pain, palpation of hard fecal masses and, in toxic megacolon, fever, low blood potassium, tachycardia and shock. Stercoral ulcers are sometimes observed in chronic megacolon, which may lead to perforation of the intestinal wall in approximately 3% of the cases, leading to sepsis and risk of death.

Rectal tenesmus (Latin, from Greek teinesmos, from teinein to stretch, strain) is a feeling of incomplete defecation. It is the sensation of inability or difficulty to empty the bowel at defecation, even if the bowel contents have already been evacuated. Tenesmus indicates the feeling of a residue, and is not always correlated with the actual presence of residual fecal matter in the rectum. It is frequently painful and may be accompanied by involuntary straining and other gastrointestinal symptoms.

Tenesmus has both a nociceptive and a neuropathic component.

Vesical tenesmus is a similar condition, experienced as a feeling of incomplete voiding despite the bladder being empty.

Often, rectal tenesmus is simply called tenesmus. The term rectal tenesmus is a retronym to distinguish defecation-related tenesmus from vesical tenesmus.

Tenesmus is a closely related topic to obstructed defecation.

Encopresis (from the Ancient Greek ἐγκόπρησις / egkóprēsis), also known as paradoxical diarrhea, is voluntary or involuntary fecal soiling in children who have usually already been toilet trained. Children with encopresis often leak stool into their undergarments.

This term is usually applied to children, and where the symptom is present in adults, it is more commonly known as fecal leakage (FL), fecal soiling or fecal seepage.

Fecalith, also called a fecaloma or faecaloma, is an extreme form of fecal impaction, often characterized by calcification. The term fecalith literally means a "stone" made of feces (lith=stone). It is a hardening of feces into lumps of varying size and may occur anywhere in the intestinal tract but is typically found in the colon. It is also called appendicolith when it occurs in the appendix and is sometimes concomitant with appendicitis. They can also obstruct diverticula.

There are many different types of rectal discharge, but the most common presentation of a discharge is passage of mucus or pus wrapped around an otherwise normal bowel movement.

Rectal discharge has many causes, and may present with other symptoms:

- Staining of undergarments

- Constant feeling of dampness around anus

- Frequent urge to open bowels, but passage of only small amounts of mucus or pus-like liquid rather than normal feces

- Rectal pain

- Rectal malodor, when the discharge is foul-smelling, e.g. associated with certain infections

- Pruritus ani

- Rectal bleeding

- Perianal erythema, swelling and tenderness

Constipation refers to bowel movements that are infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement. Complications from constipation may include hemorrhoids, anal fissure or fecal impaction. The normal frequency of bowel movements in adults is between three per day and three per week. Babies often have three to four bowel movements per day while young children typically have two to three per day.

Constipation has many causes. Common causes include slow movement of stool within the colon, irritable bowel syndrome, and pelvic floor disorders. Underlying associated diseases include hypothyroidism, diabetes, Parkinson's disease, celiac disease, non-celiac gluten sensitivity, colon cancer, diverticulitis, and inflammatory bowel disease. Medications associated with constipation include opioids, certain antacids, calcium channel blockers, and anticholinergics. Of those taking opioids about 90% develop constipation. Constipation is more concerning when there is weight loss or anemia, blood is present in the stool, there is a history of inflammatory bowel disease or colon cancer in a person's family, or it is of new onset in someone who is older.

Treatment of constipation depends on the underlying cause and the duration that it has been present. Measures that may help include drinking enough fluids, eating more fiber, and exercise. If this is not effective, laxatives of the bulk forming agent, osmotic agent, stool softener, or lubricant type may be recommended. Stimulant laxatives are generally reserved for when other types are not effective. Other treatments may include biofeedback or in rare cases surgery.

In the general population rates of constipation are 2–30 percent. Among elderly people living in a care home the rate of constipation is 50–75 percent. People spend, in the United States, more than on medications for constipation a year.

As the fecal matter gradually stagnates and accumulates in the intestine, increase in volume occurs until the intestine becomes deformed and acquires characteristics similar to that of a tumor. It may occur in chronic obstruction of stool transit, as in megacolon and chronic constipation. Some diseases, such as Chagas disease, Hirschsprung's disease and others damage the autonomic nervous system in the colon's mucosa (Auerbach's plexus) and may cause extremely large or "giant" fecalomas, which must be surgically removed (disimpaction). Rarely, a fecalith will form around a hairball (Trichobezoar), or other hygroscopic or desiccant nucleus.

Megacolon is an abnormal dilation of the colon (also called the large intestine). The dilation is often accompanied by a paralysis of the peristaltic movements of the bowel. In more extreme cases, the feces consolidate into hard masses inside the colon, called fecalomas (literally, "fecal tumor"), which can require surgery to be removed.

A human colon is considered abnormally enlarged if it has a diameter greater than 12 cm in the cecum (it is usually less than 9 cm), greater than 6.5 cm in the rectosigmoid region and greater than 8 cm for the ascending colon. The transverse colon is usually less than 6 cm in diameter.

A megacolon can be either acute or chronic. It can also be classified according to cause.

The differential diagnosis of rectal discharge is extensive, but the general etiological themes are infection and inflammation. Some lesions can cause a discharge by mechanically interfering with, or preventing the complete closure of, the anal canal. This type of lesion may not cause discharge intrinsically, but instead allow transit of liquid stool components and mucus.

- Common causes include: haemorrhoids, proctitis, anal fissure, rectal prolapse, perianal warts (anal condyloma acuminatum),

- Less common causes include: colorectal carcinoma, irritable bowel syndrome, solitary rectal ulcer syndrome, anal fistulae, villous adenoma, poor anal hygiene

- Rare causes include: sexually transmitted diseases (e.g. syphilis, rectal gonorrhea, chlamydia), anal carcinoma, AIDS, rectal foreign body, bowel obstruction, rectocele, enterocele, ulcerative colitis, bacterial colitis (e.g. syphilytic colitis), anal/perianal tuberculosis, perianal abscess (when ruptured).

Perianal Crohn's disease is associated with fistulizing, fissuring and perianal abscess formation.

After colostomy, the distal section of bowel continues to produce mucus despite fecal diversion, often resulting in mucinous discharge.

Occasionally, intestinal parasitic infection can present with discharge, for example whipworm.

The psychiatric (DSM-IV) diagnostic criteria for encopresis are:

1. Repeated passage of feces into inappropriate places (e.g., underwear or floor) whether voluntary or unintentional

2. At least one such event a month for at least 3 months

3. Chronological age of at least 4 years (or equivalent developmental level)

4. The behavior is not exclusively due to a physiological effect of a substance (e.g., laxatives) or a general medical condition, except through a mechanism involving constipation.

The DSM-IV recognizes two subtypes: with constipation and overflow incontinence, and without constipation and overflow incontinence. In the subtype with constipation, the feces are usually poorly formed and leakage is continuous, and this occurs both during sleep and waking hours. In the type without constipation, the feces are usually well-formed, soiling is intermittent, and feces are usually deposited in a prominent location. This form may be associated with oppositional defiant disorder (ODD) or conduct disorder, or may be the consequence of large anal insertions, or more likely due to chronic encopresis that has radically desensitized the colon and anus.

Tenesmus is characterized by a sensation of needing to pass stool, accompanied by pain, cramping, and straining. Despite straining, little stool is passed. Tenesmus is generally associated with inflammatory diseases of the bowel, which may be caused by either infectious or noninfectious conditions. Conditions associated with tenesmus include:

- Amebiasis

- Coeliac disease

- Chronic arsenic poisoning

- Colorectal cancer

- Anal melanoma

- Cytomegalovirus (in immunocompromised patients)

- Diverticular disease

- Hemorrhoid, which are prolapsed

- Inflammatory bowel disease

- Irritable bowel syndrome

- Ischemic colitis

- Kidney stones, when a stone is lodged in the lower ureter

- Pelvic floor dysfunction

- Radiation proctitis

- Rectal gonorrhoea

- Rectal lymphogranuloma venereum

- Rectal lower gastrointestinal parasitic infection, particularly "Trichuris trichiura" (whipworm)

- Shigellosis

- Ulcerative colitis

Tenesmus (rectal) is also associated with the installation of either a reversible or non reversible stoma where rectal disease may or may not be present. Patients who experience tenesmus as a result of stoma installation can experience the symptoms of tenesmus for the duration of the stoma presence. Long term pain management may need to be considered as a result.

A gastrojejunocolic fistula is a disorder of the human gastrointestinal tract. It may form between the transverse colon and the upper jejunum after a Billroth II surgical procedure. (The Billroth procedure attaches the jejunum to the remainder of the stomach). Fecal matter thereby passes improperly from the colon to the stomach, and causes halitosis.

Patients may present with diarrhea, weight loss and halitosis as a result of fecal matter passing through the fistula from the colon into the stomach.

Symptoms include:

- Straining during defecation

- Mucous rectal discharge

- Rectal bleeding

- Sensation of incomplete evacuation (tenesmus)

- constipation, or more rarely diarrhea

- fecal incontinence (rarely)

Fecal occult blood (FOB) refers to blood in the feces that is not visibly apparent (unlike other types of blood in stool such as melena or hematochezia). A fecal occult blood test (FOBT) checks for hidden (occult) blood in the stool (feces).

Other tests look for globin, DNA, or other blood factors including transferrin, while conventional stool guaiac tests look for heme.

Fecal incontinence to gas, liquid, solid stool, or mucus in the presence of obstructed defecation symptoms may indicate occult rectal prolapse (i.e. rectal intussusception), internal/external anal sphincter dysfunction, or descending perineum syndrome.

The small intestine consists of the duodenum, jejunum and ileum. Inflammation of the small intestine is called enteritis, which if localised to just part is called duodenitis, jejunitis and ileitis, respectively. Peptic ulcers are also common in the duodenum.

Chronic diseases of malabsorption may affect the small intestine, including the autoimmune coeliac disease, infective Tropical sprue, and congenital or surgical short bowel syndrome. Other rarer diseases affecting the small intestine include Curling's ulcer, blind loop syndrome, Milroy disease and Whipple's disease. Tumours of the small intestine include gastrointestinal stromal tumours, lipomas, hamartomas and carcinoid syndromes.

Diseases of the small intestine may present with symptoms such as diarrhoea, malnutrition, fatigue and weight loss. Investigations pursued may include blood tests to monitor nutrition, such as iron levels, folate and calcium, endoscopy and biopsy of the duodenum, and barium swallow. Treatments may include renutrition, and antibiotics for infections.

Symptom severity increases with the size of the prolapse, and whether it spontaneously reduces after defecation, requires manual reduction by the patient, or becomes irreducible. The symptoms are identical to advanced hemorrhoidal disease, and include:

- Fecal leakage causing staining of undergarments

- Rectal bleeding

- mucous rectal discharge

- Rectal pain

- Pruritus ani