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Congenital megacolon :

DESCRIPTION: | SIGNS AND SYMPTOMS: | CAUSES: | DIFFERENTIAL DIAGNOSIS: | LABORATORY: | PATHOLOGICAL FINDINGS: | SPECIAL TESTS: | IMAGING: | TREATMENT | DRUG(S) OF CHOICE | PRECAUTIONS: | ALTERNATIVE DRUGS: | PATIENT MONITORING: | POSSIBLE COMPLICATIONS: | MISCELLANEOUS

BASICS TOP

DESCRIPTION: TOP : Congenital disease of the colon, characterized by functional obstruction and accumulation of feces and massive dilatation of colon

System(s) affected: Gastrointestinal, Nervous

Genetics: Familial 50 times base rate. Sometimes associated with Down syndrome.

Incidence/Prevalence in USA: 1 in 2000 to 5000 births (Caucasians 91%, Blacks 8%, Oriental 0.5%)

Predominant age: Infancy

Predominant sex:

* Males > Females for short segment (8:2)

* Males > Females for long segment (5:4)

SIGNS AND SYMPTOMS: TOP :

* Stools in pellets or ribbons with pasty consistency

* Early infancy:

>> Onset early in infancy, newborn fails to pass meconium in 24 to 48 hours after birth

>> Obstipation

>> Marked enlargement and distention of abdomen

>> Colonic peristalsis visible

>> Vomiting

>> Palpable fecal mass

>> Growth retardation (possible)

* Older infants:

>> Failure to thrive

>> Anorexia

>> Lack of physiologic urge to defecate

>> Empty rectum on digital examination

>> Palpable colon

>> Visible peristalsis

>> Hypoalbuminemia

CAUSES: TOP Congenital absence of Auerbach's and Meissener's autonomic plexuses in bowel wall - usually limited to the colon

RISK FACTORS: TOP :

* Family history of Hirschsprung's disease

* Offspring risk if parent has short segment - 2%; if parent has long segment - up to 50%

* Sibling risk if male affected - female has 0.6% risk (short segment)

* Sibling risk if female affected - male has 18% risk (long segment)

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS: TOP :

* Megacolon, secondary (to Chagas' disease)

* Megacolon, acquired, functional

* Functional constipation

* Hypoganglionosis

* Meconium plug syndrome

* Small left colon syndrome

* Meconium ileus

LABORATORY: TOP : Electrolytes, albumin, CBC, urinalysis, thyroid function

Drugs that may alter lab results: N/A

Disorders that may alter lab results: N/A

PATHOLOGICAL FINDINGS: TOP :

* Congenital absence of Auerbach's and Meissner's autonomic plexuses in myenteric plexus of colon wall

* Obstruction may begin at anus, and may extend proximally to involve varying portions of the colon or terminal ileum

* Enormous dilatation and hypertrophy of all layers of involved colon

* Rectosigmoid aganglionosis

* Submucosal hypertrophied nerve bundles

SPECIAL TESTS: TOP :

* Proctoscopy: Ampulla empty of feces

* Biopsy: Absence of ganglia in wall of narrowed rectum

* Ano-rectal manometry

IMAGING: TOP :

* X-ray - barium enema shows:

>> Large ovoid mass mottled by small, irregular gas shadows

>> Dilatation of sigmoid colon above narrowed distal sigmoid or rectum

>> Narrowed portion rippled or segmented

>> Fluid levels within bowel

>> Diaphragm elevated

DIAGNOSTIC PROCEDURES: TOP :

* Suction aspiration biopsy of bowel wall

* Barium enema

* Proctosigmoidoscopy

* Large bowel wall biopsy

* Laparoscopy: Normal proximal colon dilatation

* Ano-rectal manometry: Internal sphincter relaxation failure

TREATMENT: TOP

APPROPRIATE HEALTH CARE: Early work-up (ambulatory or hospital). Inpatient for surgery.

GENERAL MEASURES: TOP :

* Treatment may be symptomatic or definitive

* May need emergency correction of fluid and electrolyte imbalance

* Removal of fecal accumulation - retention enemas of 3-4 ounces (90-120 mL) of mineral oil followed by repeated colonic irrigations with isotonic saline solution. Avoid use of other solutions, e.g., water, soapsuds enemas.

SURGICAL MEASURES: Surgery (inpatient) for colostomy at site in the colon proximal to aganglionic segment or resection of the aganglionic segment or bypass of the segment. Endorectal pull-through techniques may be utilized.

ACTIVITY: No restrictions

DIET:

* Dictated by stage of disease

* Diet will not control the obstipation of Hirschsprung's

* Postoperative diet - standard for age

PATIENT EDUCATION:

* After surgery instruct parents to detect and report dehydration, decreased urinary output, sunken eyes, poor skin turgor, vomiting, fever

* Encourage bonding with parents by having parents participate in child's care as much as possible

* Request enterotomy therapist to teach family

MEDICATIONS

DRUGS OF CHOICE: TOP :

* None recommended for treatment

* Preliminary to surgery: Bowel prep with neomycin or nystatin

Contraindications: N/A

PRECAUTIONS: TOP : N/A

Significant possible interactions: N/A

ALTERNATIVE DRUGS: TOP :

* Metronidazole (Flagyl) for bowel preparation

FOLLOWUP

PATIENT MONITORING: TOP : Closely until recuperated fully from surgical intervention

PREVENTION/AVOIDANCE: N/A

POSSIBLE COMPLICATIONS: TOP :

* Toxic enterocolitis, possibly fatal

* Bleeding and/or perforation

EXPECTED COURSE AND PROGNOSIS: Guardedly favorable with surgery prior to onset of complications

MISCELLANEOUS TOP

ASSOCIATED CONDITIONS:

* Chagas' disease (secondary aganglionic megacolon may be a late complication of Chagas')

* Megacolon, acquired, functional usually begins in 3rd or 4th year of life

* Down syndrome

* Septal defects

* Tetralogy of Fallot

* Dandy-Walker syndrome

* Associated with anomalies 22% of the time, especially neurological, cardiovascular, urological, gastrointestinal

AGE-RELATED FACTORS:

Pediatric: Occasionally infants have only mild or intermittent constipation with intervening bouts of diarrhea. These cases may not be diagnosed until later in infancy.

Geriatric: N/A

Others: N/A

PREGNANCY: N/A

SYNONYMS:

* Aganglionic megacolon

* Hirschsprung's disease

* Zer-Wilson's disease (total colonic aganglionosis)

ICD-9-CM:

751.3 Hirschsprung's disease

SEE ALSO:

* Constipation

OTHER NOTES: Diagnosis must be made as early as possible to prevent toxic enterocolitis

ABBREVIATIONS: N/A

REFERENCES:

* Ryan ET, et al: J of Ped Surg 1992;1:76-81

* Walsh K, et al, eds: Pediatric Surgery. New York, Yearbook Medical Publishers, 1986

* Eastwood GL, Avunduk C, eds: Manual of Gastroenterology. Boston, Little, Brown, 1988

* Barakat AY, ed: Renal Disease in Children: Clinical Evaluation & Diagnosis. New York, Springer-Verlag, 1990

Author(s):

James A. Nard, MD

Copyright - Williams & Wilkins, 1997.

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