Rectoceles result from the weakening of the pelvic floor also called pelvic organ prolapse. Weakened pelvic structures occur as a result of an episiotomy during previous births, even decades later. Other causes of pelvic floor prolapse can be advanced age, multiple vaginal deliveries, and birthing trauma. Birthing trauma includes vacuum delivery, forceps delivery, and perineal tear. In addition, a history of chronic constipation and excessive straining with bowel movements are thought to play a role in rectocele. Multiple gynecological or rectal surgeries can also lead to weakening of the pelvic floor. Births that involve babies over nine pounds in weight, or rapid births can contribute to the development of rectocele.

A hysterectomy or other pelvic surgery can be a cause, as can chronic constipation and straining to pass bowel movements. It is more common in older women than in younger ones; estrogen which helps to keep the pelvic tissues elastic decreases after menopause.

Treatment depends on the severity of the problem, and may include non-surgical methods such as changes in diet (increase in fiber and water intake), pelvic floor exercises such as Kegel exercises, use of stool softeners, hormone replacement therapy for post-menopausal women and insertion of a pessary into the vagina. A high fiber diet, consisting of 25-30 grams of fiber daily, as well as increased water intake (typically 6-8 glasses daily), help to avoid constipation and straining with bowel movements, and can relieve symptoms of rectocele.

Genital prolapse occurs in about 316 million women worldwide as of 2010 (9.3% of all females).

Mechanistically, the causes of pelvic floor dysfunction are two-fold: widening of the pelvic floor hiatus and descent of pelvic floor below the pubococcygeal line, with specific organ prolapse graded relative to the hiatus. Associations include obesity, menopause, pregnancy and childbirth. Some women may be more likely to developing pelvic floor dysfunction because of an inherited deficiency in their collagen type. Some women may have congenitally weak connective tissue and fascia and are therefore at risk of stress urinary incontinence and pelvic organ prolapse.

By definition, "postpartum" pelvic floor dysfunction only affects women who have given birth, though pregnancy rather than birth or birth method is thought to be the cause. A study of 184 first-time mothers who delivered by Caesarean section and 100 who delivered vaginally found that there was no significant difference in the prevalence of symptoms 10 months following delivery, suggesting that pregnancy is the cause of incontinence for many women irrespective of their mode of delivery. The study also suggested that the changes which occur to the properties of collagen and other connective tissues during pregnancy may affect pelvic floor function.

Pelvic floor dysfunction can result after treatment for gynegological cancers.

One of the main causes is suggested to be excessive and repetitive straining during defecation. Other causes include weakness of the pelvic floor muscles (secondary to age related neuropathic degeneration or traumatic injury during pregnancy and labor.

FI is thought to be very common, but much under-reported due to embarrassment. One study reported a prevalence of 2.2% in the general population. It affects people of all ages, but is more common in older adults (but it should not be considered a normal part of aging). Females are more likely to develop it than males (63% of those with FI over 30 may be female). In 2014, the National Center for Health Statistics reported that one out of every six seniors in the U.S. who lived in their own home or apartment had FI. Men and women were equally affected. 45–50% of people with FI have severe physical and/or mental disabilities.

Risk factors include age, female gender, urinary incontinence, history of vaginal delivery (non-Caesarean section childbirth), obesity, prior anorectal surgery, poor general health and physical limitations. Combined urinary and fecal incontinence is sometimes termed double incontinence, and it is more likely to be present in those with urinary incontinence.

Traditionally, FI was thought to be an insignificant complication of surgery, but it is now known that a variety of different procedures are associated with this possible complication, and sometimes at high levels. Examples are midline internal sphincterotomy (8% risk), lateral internal sphincterotomy, fistulectomy, fistulotomy (18-52%), hemorrhoidectomy (33%), ileo-anal reservoir reconstruction, lower anterior resection, total abdominal colectomy, ureterosigmoidostomy, and anal dilation (Lord's procedure, 0-50%). Some authors consider obstetric trauma to be the most common cause.

Pelvic organ prolapse (POP) is characterized by descent of pelvic organs from their normal positions. In women, the condition usually occurs when the pelvic floor collapses after gynecological cancer treatment, childbirth or heavy lifting.

In men, it may occur after the prostrate gland is removed. The injury occurs to fascia membranes and other connective structures that can result in cystocele, rectocele or both. Treatment can involve dietary and lifestyle changes, physical therapy, or surgery.

Internal rectal intussusception (rectal intussusception, internal intussusception, internal rectal prolapse, occult rectal prolapse, internal rectal procidentia and rectal invagination) is a medical condition defined as a funnel shaped infolding of the rectal wall that can occur during defecation.

This phenomenon was first described in the late 1960s when defecography was first developed and became widespread. Degrees of internal intussusception have been demonstrated in 40% of asymptomatic subjects, raising the possibility that it represents a normal variant in some, and may predispose patients to develop symptoms, or exacerbate other problems.

This may occur when there is a large mass of feces in the rectum (fecal loading), which may become hardened (fecal impaction). Liquid stool elements are able to pass around the obstruction, leading to incontinence. Megarectum (enlarged rectal volume) and rectal hyposensitivity are associated with overflow incontinence. Hospitalized patients and care home residents may develop FI via this mechanism, possibly a result of lack of mobility, reduced alertness, constipating effect of medication and/or dehydration.

There are 2 schools of thought regarding the nature of internal intussusception, viz: whether it is a primary phenomenon, or secondary to (a consequence of) another condition.

Some believe that it represents the initial form of a progressive spectrum of disorders the extreme of which is external rectal prolapse. The intermediary stages would be gradually increasing sizes of intussusception. The folding section of rectum can cause repeated trauma to the mucosa, and can cause solitary rectal ulcer syndrome. However, internal intussusception rarely progresses to external rectal prolapse.

Others argue that the majority of patients appear to have rectal intussusception as a consequence of obstructed defecation rather than a cause, possibly related to excessive straining in patients with obstructed defecation. Patients with other causes of obstructed defecation (outlet obstruction) like anismus also tend to have higher incidence of internal intussusception. Enteroceles are coexistent in 11% of patients with internal intussusception. Symptoms of internal intussusception overlap with those of rectocele, indeed the 2 conditions can occur together.

Patients with solitary rectal ulcer syndrome combined with internal intussusception (as 94% of SRUS patients have) were shown to have altered rectal wall biomechanics compared to patients with internal intussusception alone. The presumed mechanism of the obstructed defecation is by telescoping of the intussusceptum, occluding the rectal lumen during attempted defecation. One study analysed resected rectal wall specimens in patients with obstructed defecation associated with rectal intussusception undergoing stapled trans-anal rectal resection. They reported abnormalities of the enteric nervous system and estrogen receptors. One study concluded that intussusception of the anterior rectal wall shares the same cause as rectocele, namely deficient recto-vaginal ligamentous support.

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.

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

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."

The condition is widespread, affecting up to 50% of women at some point in their lifetime. Almost 10 percent of women will undergo surgery for urinary incontinence or pelvic organ prolapse. 30 percent of those undergoing surgery will have at least two surgeries in trying to correct the problem.

Some conditions are reversible, with pelvic floor exercises, or Kegel exercises recommended to strengthen the area muscles. Devices and probes are also available over the counter which purport to increase pelvic floor tone by stimulating muscle contractions with electrical impulses.

Anal warts are irregular, verrucous lesions caused by human papilloma virus. Anal warts are usually transmitted by unprotected, anoreceptive intercourse. Anal warts may be asymptomatic, or may cause rectal discharge, anal wetness, rectal bleeding, and pruritus ani. Lesions can also occur within the anal canal, where they are more likely to create symptoms.

Surgical treatments may be used to treat the condition, and include retro-rectal levatorplasty, post-anal repair, retro-anal levator plate myorrhaphy.

Proctitis is inflammation of the anal canal and the distal of the rectum.

Proctitis has many causes, such as infections or intercourse.

Tuberculosis proctitis can create a mucous discharge.

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.