The six-week period after pregnancy is called the postpartum stage. During this time, women are at increased risk of being constipated. Multiple studies estimate the prevalence of constipation to be around 25% during the first 3 months. Constipation can cause discomfort for women, as they are still recovering from the delivery process especially if they have had a perineal tear or underwent an episiotomy. Risk factors that increase the risk of constipation in this population include:

- Damage to the levator ani muscles (pelvic floor muscles) during childbirth

- Forceps-assisted delivery

- Lengthy second stage of labor

- Delivering a large child

- Hemorrhoids

Hemorrhoids are common in pregnancy and also may get exacerbated when constipated. Anything that can cause pain with stooling (hemorrhoids, perineal tear, episiotomy) can lead to constipation because patients may withhold from having a bowel movement so as to avoid pain.

The pelvic floor muscles play an important role in helping pass a bowel movement. Injury to those muscles by some of the above risk factors (examples- delivering a large child, lengthy second stage of labor, forceps delivery) can result in constipation. Women sometimes get enemas during labor that can also alter bowel movements in the days after having given birth. However, there is insufficient evidence to make conclusions about the effectiveness and safety of laxatives in this group of people.

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.

One review stated that the most common causes of disruption to the defecation cycle are associated with pregnancy and childbirth, gynaecological descent or neurogenic disturbances of the brain-bowel axis. Patients with obstructed defecation appear to have impaired pelvic floor function.

Specific causes include:

- Anismus and pelvic floor dysfunction

- Rectocele

- "Rectal invagination" (likely refers to rectal intussusception)

- Internal anal sphincter hypertonia

- Anal stenosis

- Fecal impaction

- Rectal or anal cancer

- Descending perineum syndrome

Liquid stool is more difficult to control than formed, solid stool. Hence, FI can be exacerbated by diarrhea. Some consider diarrhea to be the most common aggravating factor. Orlistat is an anti-obesity (weight loss) drug that blocks the absorption of fats. This may give side effects of FI, diarrhea and steatorrhea.

Ileus is a cause of colic in horses due to functional obstruction of the intestines. It most commonly seen in horses postoperatively, especially following colic surgery. Horses experiencing ileus are at risk for gastric rupture due to rapid reflux build-up, and require intense medical management with frequent nasogastric intubation. Ileus may increase adhesion formation, because intestinal segments have more prolonged contact and intestinal distention causes serosal injury and ischemia. It is usually treated with aggressive fluid support, prokinetics, and anti-inflammatories.

Continence requires conscious and subconscious networking of information from and to the anorectum. Defects/brain damage may affect the central nervous system focally (e.g. stroke, tumor e.g. spinal cord lesions, trauma, multiple sclerosis) or diffusely (e.g. dementia, multiple sclerosis, infection, Parkinson's disease or drug-induced). FI (and urinary incontinence) may also occur during epileptic seizures. Dural ectasia is an example of a spinal cord lesion that may affect continence.

Approximately 3% of children have constipation, with girls and boys being equally affected. With constipation accounting for approximately 5% of general pediatrician visits and 25% of pediatric gastroenterologist visits, the symptom carries a significant financial impact upon the healthcare system. While it is difficult to assess an exact age at which constipation most commonly arises, children frequently suffer from constipation in conjunction with life-changes. Examples include: toilet training, starting or transferring to a new school, and changes in diet. Especially in infants, changes in formula or transitioning from breast milk to formula can cause constipation. Fortunately, the majority of constipation cases are not tied to a medical disease, and treatment can be focused on simply relieving the symptoms.

Obstructed defecation has many causes, so the management in any individual case is specific to the cause of the symptom. For rectal internal intususception treatment is surgical, either STARR or rectopexy. For rectocele STARR or mesh implantation. For anismus/ pelvic floor dessynergia: biofeedback exercise.

Several definitions have been offered:

- "Absence of normal relaxation of pelvic floor muscles during defecation, resulting in rectal outlet obstruction".

- "Malfunction (a focal dystonia) of the external anal sphincter and puborectalis muscle during defecation".

- "[...] failure of [the external anal sphincter and puborectalis] muscle[s] to relax, resulting in maintenance of the anorectal angle and the difficulty with initiating and completing bowel movements".

- "[...] failure of relaxation (or paradoxic contraction) of the puborectalis muscle sling during defaecation, attempted defaecation or straining."

Pain relief is administered concomitantly to the treatment of the primary disease causing tenesmus. Methadone has been shown to be an effective pain-reliever.

Anismus is classified as a functional defecation disorder. It is also a type of rectal outlet obstruction (a functional outlet obstruction). Where anismus causes constipation, it is an example of functional constipation. Some authors describe an "obstructed defecation syndrome", of which anismus is a cause.

The Rome classification subdivides functional defecation disorders into 3 types, however the symptoms the patient experiences are identical.

- Type I: paradoxical contraction of the pelvic floor muscles during attempted defecation

- Type II: inadequate propulsive forces during attempted defecation (inadequate defecatory propulsion)

- Type III: impaired relaxation with adequate propulsion

It can be seen from the above classification that many of the terms that have been used interchangeably with anismus are inappropriately specific and neglect the concept of impaired propulsion. Similarly, some of the definitions that have been offered are also too restrictive.

The prognosis for non-ischemic cases of SBO is good with mortality rates of 3–5%, while prognosis for SBO with ischemia is fair with mortality rates as high as 30%.

Cases of SBO related to cancer are more complicated and require additional intervention to address the malignancy, recurrence, and metastasis, and thus are associated with poorer prognosis.

All cases of abdominal surgical intervention are associated with increased risk of future small-bowel obstructions. Statistics from U.S. healthcare report 18.1% re-admittance rate within 30 days for patients who undergo SBO surgery. More than 90% of patients also form adhesions after major abdominal surgery.

Common consequences of these adhesions include small-bowel obstruction, chronic abdominal pain, pelvic pain, and infertility.

Fetal and neonatal bowel obstructions are often caused by an intestinal atresia, where there is a narrowing or absence of a part of the intestine. These atresias are often discovered before birth via an ultrasound, and treated with using laparotomy after birth. If the area affected is small, then the surgeon may be able to remove the damaged portion and join the intestine back together. In instances where the narrowing is longer, or the area is damaged and cannot be used for a period of time, a temporary stoma may be placed.

Paralysis of the intestine is often termed paralytic ileus, in which the intestinal paralysis need not be complete, but it must be sufficient to prohibit the passage of food through the intestine and lead to intestinal blockage. Paralytic ileus is a common side effect of some types of surgery, commonly called postsurgical ileus. It can also result from certain drugs and from various injuries and illnesses, such as acute pancreatitis. Paralytic ileus causes constipation and bloating. On listening to the abdomen with a stethoscope, no bowel sounds are heard because the bowel is inactive.

A temporary paralysis of a portion of the intestines occurs typically after abdominal surgery. Since the intestinal content of this portion is unable to move forward, food or drink should be avoided until peristaltic sound is heard, by auscultation (use of a stethoscope) of the area where this portion lies. Intestinal atony or paralysis may be caused by inhibitory neural reflexes, inflammation or other implication of neurohumoral peptides.

Any condition that impairs bladder and bladder outlet afferent and efferent signaling can cause neurogenic bladder.

It is often associated with spinal cord diseases (such as syringomyelia/hydromyelia), injuries (like herniated disks), and neural tube defects including spina bifida.

It may also be caused by brain tumors and other diseases of the brain, pregnancy and by peripheral nerve diseases such as: Diabetes, Alcoholism (and Vitamin B12 deficiency).

It is a common complication of major surgery in the pelvis, such as for removal of sacrococcygeal teratoma and other tumors.

There is considerable research into the causes, diagnosis and treatments for FGIDs. Diet, microbiome, genetics, neuromuscular function and immunological response all interact. Heightened mast cell activation has been proposed to be a common factor among FGIDs, contributing to visceral hypersensitivity as well as epithelial, neuromuscular, and motility dysfunction.

It is unclear what role dietary fibre plays in diverticulitis. It is often stated that a diet low in fibre is a risk factor; however, the evidence to support this is unclear. There is no evidence to suggest that the avoidance of nuts and seeds prevents the progression of diverticulosis to an acute case of diverticulitis. It appears in fact that a higher intake of nuts and corn could help to avoid diverticulitis in adult males.

The causes of diverticulitis are poorly understood, with approximately 40 percent due to genes and 60 percent due to environmental factors. Conditions that increase the risk of developing diverticulitis include arterial hypertension and immunosuppression. Obesity is another risk factor.

The condition is diagnosed most often in infancy and early childhood. It strikes about 2,000 infants (one in every 1,900) in the United States in the first year of life. Its incidence begins to rise at about one to five months of life, peaks at four to nine months of age, and then gradually declines at around 18 months.

Intussusception occurs more frequently in boys than in girls, with a ratio of approximately 3:1.

In adults, intussusception represents the cause of approximately 1% of bowel obstructions and is frequently associated with neoplasm, malignant or otherwise.

Catheterization methods range from intermittent catheterization, which involves no surgery or permanently attached appliances, to the creation of a stoma, which bypasses the urethra to empty the bladder directly.

Intermittent catheterization is the use, several times a day, of straight catheters (which are usually disposable or single-use products) to empty the bladder. This can be done independently by the patient, or with help, in the case that the patient lacks the dexterity to manage the catheter. For patients who are unable to tolerate disposable straight catheters, a Foley catheter allows continuous drainage of urine into a sterile drainage bag that is worn by the patient.

Other treatments involve creation of a stoma that is continent and readily accepts a catheter. These are known as Mitrofanoff mechanisms. An example of this treatment is the creation of an Indiana pouch. Additionally, a muscarinic agonist like Bethanechol may also be used, particularly in the postpartum or postoperative period. Function of the stoma may be augmented by periodic injections of botulinum toxin to relax one of the two sphincters involved in normal urination. The effect is longer-lasting with botulinum toxin type A than with type B. This use of botulinum toxin is discussed at length in the French medical literature.

Laparotomy for other forms of volvulus, especially anal volvulus.

Bowel infarction results from restricted blood supply to the bowel, most often due to bowel obstruction or occlusion of one of the mesenteric arteries.

Bowel obstruction is most often caused by intestinal adhesions, which frequently form after abdominal surgeries, or by chronic infections such as diverticulitis, hepatitis, and inflammatory bowel disease. The condition is difficult to diagnose properly, as the symptoms may resemble those of other bowel disorders.

Patients who have undergone extensive resection of the small bowel may develop malabsorption, indicating the need for dietary supplements.

Volvulus is a rare but life-threatening cause of bowel infarction which requires immediate medical attention. Central abdominal pain which is resistant to narcotic analgesia may be an indication of bowel infarction.

With early intervention, morbidity and mortality of cases of intestinal obstruction is low. The outcome is in part dependent upon congenital comorbidities and delays in diagnosis and management.

Toxic megacolon is mainly seen in ulcerative colitis and pseudomembranous colitis, two chronic inflammations of the colon (and occasionally, in the other type of inflammatory bowel disease, Crohn's disease). Its mechanism is incompletely understood. It is probably due to an excessive production of nitric oxide, at least in ulcerative colitis. The prevalence is about the same for both sexes.

In patients with HIV/AIDS, cytomegalovirus (CMV) colitis is the leading cause of toxic megacolon and emergency laparotomy. CMV may also increase the risk of toxic megacolon in non-HIV/AIDS patients with IBD.

Risperidone, an anti-psychotic medication, can result in megacolon.