Gastrointestinal

Stephanie

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Defecation

Is the process of passing out stool (feces) through the anus. This eliminates waste material from the rectum and colon. The process of defecation should be painless, regular and to a certain degree, it is under voluntary control.

Defecation reflexesAn involuntary response of the lower bowels to

various stimuli there by promoting or even inhibiting a bowel movement.

These reflexes are under the control of the autonomic system and play an integral role in the defecation process along with the somatic system that is responsible for voluntary control of defecation.

The two main defecation reflexes are known as the intrinsic myenteric defecation reflex and parasympathetic defecation reflex.

Other Defecation Reflexes

• Apart from the two main defecation reflexes mentioned above, other reflexes can also influence the defecation process.– Gastrocolic reflex – distention of the stomach while eating or

immediately after a meal triggers mass movements in the colon.– Gastroileal reflex – distention of the stomach while eating or

immediately after eating triggers the relaxation of the ileocecal sphincter and speeds up peristalsis in the ileum (end portion of the small intestine). This causes the contents of the ileum to rapidly empty into the colon.

– Enterogastric reflex – distention and/or acidic chyme in the duodenum slows stomach emptying and reduces peristalsis.

– Duodenocolic reflex – distention of the duodenum a short while after eating triggers mass movements in the colon.

PROCESS OF DEFECATION

Phase of Defecation

http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=spinalcord&part=A2598

Constipation

Definition :◦Constipation is a symptom◦ issues of stool consistency (hard, painful stools)◦ issues of defecating behavior

Infrequency (<3x per week) Difficulty in defecation Straining during defecation (>25% bowel movement) Subjective sensation of hard stool Incomplete bowel evacuation

– For surgical purposes :• Change in the bowel habit• Defecatory behavior that results in acute or chronic

symptoms• Diseases that would be resolved with relief of the

constipation

– Health care providers : • Frequency of bowel movements (< 3 bowel movements

per week) to define constipation

• According to Rome III (at least 2 symptoms over the past 3 months) :– Less than 3 bowel movements per week– Straining– Lumpy/hard stools– Sensation of anorectal obstruction– Sensation of incomplete defecation– Manual maneuvering required to defecate

Causes

Common causes of constipation are:not enough fiber in the dietlack of physical activity (especially in the elderly)medicationsmilkirritable bowel syndromechanges in life or routine such as pregnancy, aging, and travelabuse of laxativesignoring the urge to have a bowel movementdehydrationspecific diseases or conditions, such as stroke (most common)problems with the colon and rectumproblems with intestinal function (chronic idiopathic constipation)

Causes

• 2 main groups :– Primary Constipation– Secondary Constipation

Primary ConstipationPrimary (idiopathic, functional) constipation can

generally be classified into 3 categories:◦ Normal-transit constipation (NTC)

Patients perceive difficulty in evacuating their bowels◦ Slow-transit constipation (STC)

Infrequent bowel movements, decreased urgency, or straining to defecate. (mild abdominal distention or palpable stool in the sigmoid colon)

◦ Pelvic floor dysfunction (ie, pelvic floor dyssynergia) dysfunction of the pelvic floor or anal sphincter. Patients often

report prolonged or excessive straining, feeling of incomplete evacuation, or the use of perineal or vaginal pressure during defecation to allow the passage of stool or report digital evacuation of stool.

Secondary Constipation

• Diet and exercise • Structural • Endocrinopathic and metabolic• Drugs• Neurologic• Connective-tissue disorders• Toxicologic • Psychologic

Types of Constipation and Causes Examples

Recent onset :

- colonic obstruction Neoplasm, stricture, ischemic, diverticular, inflammatory

- Anal sphincter spasm Anal fissure, painful hemorrhoids

- Medications

Chronic

- IBS Constipation-predominant, alternating

- Medications Ca²⁺ blockers, antidepressants

- colonic pseudo-obstruction Slow transit constipation, megacolon (rare Hirschsprung’s, chagas)

- Disorders of rectal evacuation Pelvic floor dysfunction,anismus,descending perineum syndrom,rectal mucosal prolapse, rectocele

- Endocrinopathies Hypothyroidism, hypercalcemia, pregnancy

- Psychiatric disorders Depression, eating disorders, drugs

- neurologic disease Parkinsonism, multiple sclerosis, spinal cord injury

- generalized muscle disease Progressive systemic sclerosis

Patophysiology

• Constipation occurs if defecation is delayed for too long

• The longer colonic contents being retained, the more amount of H2O is absorbed hard & dry in consistency

DIAGNOSTICMedical History- The doctor may ask a patient to describe his or her constipation, including

duration of symptoms, frequency of bowel movements, consistency of stools, presence of blood in the stool, and toilet habits—how often and where one has bowel movements. A record of eating habits, medication, and level of physical activity will also help the doctor determine the cause of constipation.

- The clinical definition of constipation is having any two of the following symptoms for at least 12 weeks—not always consecutive—in the previous 12 months:

straining during bowel movements lumpy or hard stoolsensation of incomplete evacuationsensation of anorectal blockage/obstruction fewer than three bowel movements per week

Physical Examination- A physical exam may include a rectal exam with a gloved, lubricated finger

to evaluate the tone of the muscle that closes off the anus—also called anal sphincter—and to detect tenderness, obstruction, or blood. In some cases, blood and thyroid tests may be necessary to look for thyroid disease and serum calcium or to rule out inflammatory, metabolic, and other disorders.

- Extensive testing usually is reserved for people with severe symptoms, for those with sudden changes in the number and consistency of bowel movements or blood in the stool, and older adults. Additional tests that may be used to evaluate constipation include:

a colorectal transit studyanorectal function testsa defecography- Because of an increased risk of colorectal cancer in older adults, the

doctor may use tests to rule out a diagnosis of cancer, including abarium enema x raysigmoidoscopy or colonoscopy

CONSTIPATION

• The child may be constipated if one or more of the following are true:

1.He or she has fewer than 3 bowel movements a week.

2.The stools are hard, dry and unusually large.3.The stools are difficult to pass.

• For some children, it is normal to pass stools as far apart as every few days. Whether your child is constipated or not depends on how often he or she normally passes stools and how easy this is to do. If stools are soft and easy to pass, less frequent stools are not a problem.

• If the children is hard and difficult to pass, your child is likely constipated.

• If the child is having trouble with constipation for more than 2 weeks, it is called chronic constipation.

Normal frequency of bowelmovements in children

Age Bowel movementsper week

Bowel movementsPer day

0-3 months breast fed 5 to 40 2,9 stools/day

0-3 months formula fed 5-28 2 stools/day

6-12 months 5-28 1.8 stools/day

1-3 years 4 to 21 1.4 stools/day

>3years 3 to 14 1.0 stools/day

Red flag signs or symptoms of possible organiccauses of constipation in infants and young children

Passage of meconium more Hirschsprungs diseasethat 48 hr after delivery aswell as other signs such assmall thin stools, vomiting,failure to thrive, tight analsphincter with empty rectumand abdominal distension

Hirschsprungs disease

Abnormal position orappearance of anus onexamination

Anteriorly displaced anusAnal stenosis

Poor growth, dry skin, Hypothyroidismbradycardia

Hypothyroidism

Treatment

• Diet• drinking enough fluids• Increase exercise • Bowel habit training• Medicine (laxative)

GI BLEEDING IN GI BLEEDING IN CHILDRENCHILDREN

HIRSCHSPRUNG DISEASE

definitions

• Congenital megacolon

• HD is characterized by the absence of myenteric and submucosal ganglion cells in the distal alimentary tract; resulting in decreased motility in the affected bowel segment

Pathophysiology

• Hirschsprung disease results from the absence of parasympathetic ganglion cells in the myenteric and submucosal plexus of the rectum and/or colon.

• Ganglion cells, which are derived from the neural crest, migrate caudally with the vagal nerve fibers along the intestine.

• These ganglion cells arrive in the proximal colon by 8 weeks of gestational age and in the rectum by 12 weeks of gestational age.

• Arrest in migration leads to an aganglionic segment.

Frequency

• approximately 1 per 5000 live births.

• Sex: 4 times more common in ♂ than ♀• Age:

– Nearly all children with Hirschsprung disease are diagnosed during the first 2 years of life.

– one half are diagnosed before they are aged 1 year. – Minority not recognized until later in childhood or adulthood.

• Mortality/Morbidity:– The overall mortality of Hirschsprung enterocolitis is 25-30%, which

accounts for almost all of the mortality from Hirschsprung disease.

HD can be classified by the extension of the aganglionosis as follows:

• Classical HD (75% of cases): Rectosegmoid• Long segment HD (20% of cases) • Total colonic aganglionosis (3-12% of cases)• rare variants include the following:

– Total intestinal aganglionosis – Ultra-short-segment HD (involving the distal

rectum below the pelvic floor and the anus)

Clinical presentation:• Newborns :

– Failure to pass meconium within the first 48 hours of life – Abdominal distension that is relieved by rectal stimulation or

enemas – Vomiting – Neonatal enterocolitis

• Symptoms in older children and adults include the following: – Severe constipation – Abdominal distension – Bilious vomiting – Failure to thrive

HD-Assosciated enterocolitis

• abdominal distension, explosive diarrhea, vomiting, fever, lethargy, rectal bleeding, or shock

• The risk is greatest:– before HD is diagnosed– after the definitive pull-through operation.– children with Down syndrome

diagnostic workup

• Plain abdominal radiography

• Contrast enema

• Manometry

• Biopsy

Abdomenal X-Ray

• Dilated bowel

• Air-fluid levels.

• Empty rectum

barium enema

• Transition zone

• Abnormal, irregular contractions of aganglionic segment

• Delayed evacuation of barium

Manometry

• Absence of normal relaxation of the internal sphincter when the rectum is distended with a balloon.

Biopsy

• Types:– rectal suction biopsy – full-thickness rectal biopsy.

• In HD, the biopsy reveals:– absence of ganglion cells– hypertrophy and hyperplasia of nerve fibers, – increase in acetylcholinesterase-positive

nerve fibers in the lamina propria and muscularis mucosa.

treatment

• The treatment is surgical removal or bypass of the aganglionic bowel,

• This can be performed by means of:– preliminary colostomy followed by a definitive

pull-through procedure or,– primary definitive procedure.

• Examples include:– Soave pull-through procedure,– Duhamel procedure, – Swenson procedure.

Enterocolitis

• Enterocolitis accounts for significant morbidity and mortality in patients with Hirschsprung disease.– Patients typically present with explosive diarrhea, abdominal

distention, fever, vomiting, and lethargy.– Approximately 10-30% of patients with Hirschsprung disease

develop enterocolitis. Long-segment disease is associated with an increased incidence of enterocolitis.

– Treatment consists of rehydration, intravenous antibiotics and colonic irrigations.

Post operative complications

• anastomotic leak

• anastomotic stricture

• intestinal obstruction

• pelvic abscess

• wound infection

Prognosis

• The long-term outcome is difficult to determine because of conflicting reports in the literature.

• Some investigators report a high degree of satisfaction, while others report a significant incidence of constipation and incontinence.

• approximately 1% of patients with Hirschsprung disease require a permanent colostomy to correct incontinence.

• patients with associated trisomy 21 have poorer clinical outcomes.

Anal fissureAnal fissureDefinitionDefinition

• An anal fissure is a small split or tear in the thin moist tissue An anal fissure is a small split or tear in the thin moist tissue (mucosa) lining the lower rectum (anus).(mucosa) lining the lower rectum (anus).

CausesCauses• Anal fissures are extremely common in young infants but may Anal fissures are extremely common in young infants but may

occur at any age. Studies suggest 80% of infants will have had occur at any age. Studies suggest 80% of infants will have had an anal fissure by the end of the first year. The rate of anal an anal fissure by the end of the first year. The rate of anal fissures decreases rapidly with age. Fissures are much less fissures decreases rapidly with age. Fissures are much less common among school-aged children than infants.common among school-aged children than infants.

• In adults, fissures may be caused by constipation, the passing In adults, fissures may be caused by constipation, the passing of large, hard stools, or by prolonged diarrhea. In older adults, of large, hard stools, or by prolonged diarrhea. In older adults, anal fissures may be caused by decreased blood flow to the anal fissures may be caused by decreased blood flow to the area.area.

• Anal fissures are also common in women after childbirth and Anal fissures are also common in women after childbirth and persons with Crohn's diseasepersons with Crohn's disease

SymptomsSymptoms• Anal fissures may cause painful bowel movements Anal fissures may cause painful bowel movements

and bleeding. There may be blood on the outside of and bleeding. There may be blood on the outside of the stool or on the toilet tissue (or baby wipes) the stool or on the toilet tissue (or baby wipes) following a bowel movement.following a bowel movement.

• Other symptoms may include:Other symptoms may include:– A crack in the skin that can be seen when the area A crack in the skin that can be seen when the area

is stretched slightly (the fissure is almost always in is stretched slightly (the fissure is almost always in the middle)the middle)

– ConstipationConstipation

Exams and TestsExams and Tests• The health care provider will perform a rectal exam The health care provider will perform a rectal exam

and look at a sample of the rectal (anal) tissue.and look at a sample of the rectal (anal) tissue.

TreatmentTreatmentMost fissures heal on their own and do not require Most fissures heal on their own and do not require treatment, aside from good diaper hygiene in babies.treatment, aside from good diaper hygiene in babies.However, some fissures may require treatment. The However, some fissures may require treatment. The following home care methods usually heal most anal following home care methods usually heal most anal fissures.fissures.

* Cleansing more gently* Cleansing more gently * Diet changes -- eating more bulk, substances that absorb * Diet changes -- eating more bulk, substances that absorb

water while in the intestinal tractwater while in the intestinal tract * Muscle relaxants applied to the skin* Muscle relaxants applied to the skin * Numbing cream, if pain interferes with normal bowel * Numbing cream, if pain interferes with normal bowel

movementmovement * Petroleum jelly applied to the area* Petroleum jelly applied to the area * Sitz bath* Sitz bath * Stool softeners* Stool softeners

If the anal fissues do not go away with home care methods, If the anal fissues do not go away with home care methods, treatment may involve:treatment may involve:

* Botox injections into muscle in the anus (anal sphincter)* Botox injections into muscle in the anus (anal sphincter) * Minor surgery to relax the anal muscle* Minor surgery to relax the anal muscle

PreventionPrevention• To prevent anal fissures in infants, To prevent anal fissures in infants,

be sure to change diapers be sure to change diapers frequently.frequently.

• To prevent fissures at any age:To prevent fissures at any age:* Keep the anal area dry* Keep the anal area dry* Wipe with soft materials or a * Wipe with soft materials or a moistened cloth or cotton padmoistened cloth or cotton pad* Promptly treat any constipation or * Promptly treat any constipation or diarrheadiarrhea* Avoid irritating the rectum* Avoid irritating the rectum