Obstructed defecation

Definition and classification of constipation Constipation is usually divided into two groups: primary and secondary. ODS is a loose term, consisting of a constellation of possible symptoms, and poorly understood disorders which may include both functional and organic disorders. The topic of defecation disorders is very complicated, and there is a lot of confusion regarding terminology and classification in published literature. inappropriately treat ODS as a synonym of anismus. Although anismus is a major cause of ODS, there are other possible causes. Furthermore, many different terms have been used for ODS, which appear to refer to the same clinical entity. The term ODS does not appear in the ICD-11 and Rome-IV classifications, which both instead refer to "functional defecation disorders". One publication criticized such classifications as being ambiguous and based on symptoms rather than distinct etiopathological entities. A revised consensus statement was published by the ASCRS in 2018. wherein ODS is defined as "a subset of functional constipation in which patients report symptoms of incomplete rectal emptying with or without an actual reduction in the number of bowel movements per week." • Functional defecation disorders: this is listed as a sub-entry of functional anorectal disorders (above). It includes dyssynergic defecation (defined as "paradoxical contraction or inadequate relaxation of the pelvic floor muscles during attempted defecation"), and inadequate defecatory propulsion (defined as "inadequate propulsive forces during attempted defecation"). A note is added: "The patients must satisfy diagnostic criteria for functional constipation." • Incomplete defecation: this entity (ME07.1) exists as a sub-code of fecal incontinence, with no definition. Rome-IV The term "obstructed defecation syndrome" does not appear in the Rome IV classification. However, diagnostic criteria for functional defecation disorders are listed. According to Rome-IV, this is defined as "features of impaired evacuation" during repeated attempts to defecate. To qualify for this diagnosis, patients must meet the Rome diagnostic criteria for functional constipation or irritable bowel syndrome with constipation (IBS-C). Furthermore, 2 of the following 3 tests must show abnormal results: balloon expulsion test, anorectal manometry or anal surface electromyography, or imaging (e.g. defecography). Two subcategories exist within the functional defecation disorders category: Inadequate defecatory propulsive (F3a) and Dyssynergic defecation (F3b). These are defined as "Inadequate propulsive forces as measured with manometry with or without inappropriate contraction of the anal sphincter and/or pelvic floor muscles", and "Inappropriate contraction of the pelvic floor as measured with anal surface EMG or manometry with adequate propulsive forces during attempted defecation" respectively. The subcategories F3a and F3b are defined by age- and gender-appropriate normal values for the technique. For all of these Rome-IV diagnoses, diagnostic criteria must have been fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis. ==Signs and symptoms==

There is a constellation of possible symptoms. • Use of, or dependence on, enemas and/or laxatives. • Frequent urge to defecate, where only fecal pellets may be passed. • Pelvic heaviness. • Fecal incontinence, Where ODS occurs with fecal incontinence, it may represent fecal impaction combined with overflow diarrhea (overflow incontinence). Gloves are used for hygiene. Vaginal digitation is when the patient presses the posterior (back) wall of the vagina to support it, or to push the rectocele pouch from inside the vagina, which makes the anorectum straight and facilitates defecation. "Milking" pressure can also be applied on the posterior vaginal wall. Perineal digitation (also termed "splinting"), is pushing on the perineum (or buttocks), which acts to stimulate the transverse muscles of the perineum causing a reflex contraction of the rectum which helps to evacuate the feces. Rectal digitation is when patients insert a finger into the anus to "hook" out fecal pellets, or to apply pressure to the walls of the anus and/or the rectum (distension of which may trigger a bowel movement), or to support an obstructing anatomic defect such as a sigmoidocele. Possible complications of rectal digitation are injury of the lining of the rectum, such as ulcerations with bleeding and discomfort, and anal fibrosis leading to a rectal stricture. ==Pathophysiology==

Relevant anatomy and physiology In order to understand ODS, it is necessary to understand the normal anatomy and defecation process. Defecation is a complex physiologic process, Pathophysiology A significant pathophysiological factor in obstructed defecation is dysfunction of anorectal and colon motility, and impaired pelvic floor function. The pathophysiologic mechanisms are thought to be different in obstructed defecation compared with slow transit constipation. Enteric glial cells comprise most of the cells in the enteric ganglia. They are important for motility in the gastrointestinal tract, especially in the colon. They have many functions such as playing a role in neurotransmission, facilitating synaptic communication in enteric neurons, maintenance of homeostatic function of enteric neurons. They are involved in inflammatory processes and immune system processes in the gut and in perception of visceral pain. They also have a mechanical support function since they adhere to the surface of enteric ganglia and nerves with filaments of glial fibrillary acid protein. These cells synchronize various elements of the enteric nervous system, and their loss may significantly impact colonic motility. The authors concluded that at least a subgroup of patients with obstructed defecation have abnormalities of the enteric nervous system, specifically reduction of enteric glial cells. Another author stated that the most common cause of obstructed defecation, especially in elderly people, was denervation and weakness of the pelvic floor caused by fecal impaction and chronic straining. ==Causes==

Classification The causes of ODS are often considered in 2 groups: functional (physiologic) disorders and mechanical (anatomic / organic) disorders. It can also be classified into four groups. • Functional outlet obstruction :* Inefficient inhibition of the internal anal sphincter ::* Short-segment Hirschsprung's disease (aganglionic rectum). • Dissipation of force vector ::* Rectocele. ::* Rectal prolapse. Rectocele or intussusception are detected in about 90% of people with ODS. According to one report, 88% of cases develop after by hemorrhoidectomy. However, overall it is a rare complication of hemorrhoidectomy (less than 1.5%). Removal of too much anoderm and hemorrhoidal rectal mucosa during this procedure causes scarring and progressive narrowing. Other types of surgical procedure for recurrent anal fissures, abscesses and anal fistulae may cause anal stenosis. Other causes include Crohn's disease, radiotherapy, removal of perianal skin lesions e.g. in Paget disease or Bowen disease, tuberculosis, actinomycosis, lymphogranuloma, anal and rectal cancers and developmental abnormalities of the anus. Some authors describe a "muscular" type of anal stenosis (i.e. a functional disorder). Functional anal stenosis disappears under anesthesia, whereas true anal stenosis does not. The main symptoms of anal stenosis are difficult evacuation of stool, narrow stools, painful defecation, need for self-digitation to achieve defecation, bleeding from anal tears, and constipation. Other anatomic defects Abnormalities in the rectal wall occur with descent of the pelvic floor and pelvic organ prolapse. With increasing descent, the rectum assumes one of 3 possible configurations: internal rectal intussusception (most common), S-shaped rectum or corkscrew rectum. Sometimes internal rectal intussusception exists in combination with S-shaped rectum or corkscrew rectum. Which configuration the rectum ends up in is likely related to several factors: the original position of the rectum, the amount of redundancy of the sigmoid colon (see: dolichosigmoid colon), position of other pelvic organs, laxity of perirectal fascia, and any fixed points resulting from previous surgeries. Both S-shaped rectum and Corkscrew rectum result from abnormal lateral bending or spiral coiling of the colon. These configurations give similar symptoms (but corkscrew rectum is more likely to be symptomatic). Typically such patients complain of defecation urgency and frequent bowel movements, but only small fecal pellets are passed leaving a sensation of incomplete evacuation. During defecation patients may need to support the perineum on both sides, or evacuate fecal pellets from the rectum with a finger. There may be post defecation incontinence. These rectal wall abnormalities may be an important missed cause of obstructed defecation. S-shaped rectum and corkscrew rectum are both treated in the same way. During surgery anatomic defects in the sigmoid colon are sometimes observed in patients with ODS, such as acute bends which are stuck laterally (to one side of) or in front of the rectum. Many such defects may arise after hysterectomy because surgical adhesions in the pelvis may occur with scarring after the surgery. Without treatment, over time the patient needs to strain more, or use digitations more. This slowly leads to worsening of the anatomic defects. For example, the bends in the bowel may become more acute, and therefore cause greater symptoms. ==Diagnosis==

Diagnosis is very challenging for clinicians, since most patients will simply complain of "constipation". There are 7 parameters, scored from 0-4: • Mean time spent at the toilet • Number of attempts to defaecate per day • Anal/vaginal digitation • Use of laxatives • Use of enemas • Incomplete/fragmented defaecation • Straining at defaecation • Stool consistency Investigations There are many different investigations which are used in the diagnosis of ODS. Some authors state that multiple different diagnostic tests are required because of the coexistence of multiple causative factors, Due to the invasive and perhaps uncomfortable nature of these investigations, the pelvic floor musculature is thought to behave differently than under normal circumstances.