Overview

Definition and classification

Megacolon is a severe dilatation of thecolonColonThe large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.Colon, Cecum, and Appendix: Anatomy secondary to impairedmotilityMotilityThe motor activity of the gastrointestinal tract.Gastrointestinal Motility or an inflammatory process. The condition is classified based on the time course and duration:

• Acute megacolon
• Chronic megacolon

Epidemiology

• ExactincidenceIncidenceThe number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time.Measures of Disease Frequency is unknown.
• All ages may be affected.
• IncidenceIncidenceThe number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time.Measures of Disease Frequency depends on the underlying disease:
  • Congenital aganglionic megacolon:
    • 1 in 5,000 live births
    • Men > women
  • Toxic megacolon:
    • 4.3% inpatientsPatientsIndividuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures.Clinician–Patient Relationship withClostridioides difficile, previously known asClostridium difficileClostridium difficileA common inhabitant of the colon flora in human infants and sometimes in adults. The type species clostridioides difficile is formerly known as Clostridium difficile. It is a causative agent for clostridioides infections and is associated with pseudomembranous enterocolitis in patients receiving antibiotic therapy.Clostridia,colitisColitisInflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever.Pseudomembranous Colitis
    • 1%–10% in inflammatory bowel disease (IBD)

Etiology of acute megacolon

• Toxic megacolon (non-obstructive colonic dilation with systemictoxicityToxicityDosage Calculation)
  • IBD
    • UlcerativecolitisColitisInflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever.Pseudomembranous Colitis
    • Crohn’s disease
  • Ischemic colitisIschemic colitisInflammation of the colon due to colonic ischemia resulting from alterations in systemic circulation or local vasculature.Large Bowel Obstruction
  • InfectiouscolitisColitisInflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever.Pseudomembranous Colitis
    • C. difficilecolitisColitisInflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever.Pseudomembranous Colitis (most common)
    • SalmonellaSalmonellaSalmonellae are gram-negative bacilli of the family Enterobacteriaceae. Salmonellae are flagellated, non-lactose-fermenting, and hydrogen sulfide-producing microbes. Salmonella enterica, the most common disease-causing species in humans, is further classified based on serotype as typhoidal (S. typhi and paratyphi) and nontyphoidal (S. enteritidis and typhimurium).Salmonella
    • ShigellaShigellaShigella is a genus of gram-negative, non-lactose-fermenting facultative intracellular bacilli. Infection spreads most commonly via person-to-person contact or through contaminated food and water. Humans are the only known reservoir.Shigella
    • CampylobacterCampylobacterCampylobacter (“curved bacteria”) is a genus of thermophilic, S-shaped, gram-negative bacilli. There are many species of Campylobacter, with C. jejuni and C. coli most commonly implicated in human disease.Campylobacter
    • Escherichia coli O157Escherichia coli O157A verocytotoxin-producing serogroup belonging to the o subfamily of Escherichia coli which has been shown to cause severe food-borne disease. A strain from this serogroup, serotype h7, which produces shiga toxins, has been linked to human disease outbreaks resulting from contamination of foods by E. coli o157 from bovine origin.Diarrheagenic E. coli
    • CytomegalovirusCytomegalovirusCMV is a ubiquitous double-stranded DNA virus belonging to the Herpesviridae family. CMV infections can be transmitted in bodily fluids, such as blood, saliva, urine, semen, and breast milk. The initial infection is usually asymptomatic in the immunocompetent host, or it can present with symptoms of mononucleosis.Cytomegalovirus (CMV)colitisColitisInflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever.Pseudomembranous Colitis (usually in immunodeficientpatientsPatientsIndividuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures.Clinician–Patient Relationship)
    • Entamoeba histolyticaEntamoeba HistolyticaA species of parasitic protozoa causing entamoebiasis and amebic dysentery (dysentery, amebic). Characteristics include a single nucleus containing a small central karyosome and peripheral chromatin that is finely and regularly beaded.Amebicides
• Acutecolonic pseudo-obstructionColonic pseudo-obstructionFunctional obstruction of the colon leading to megacolon in the absence of obvious colonic diseases or mechanical obstruction. When this condition is acquired, acute, and coexisting with another medical condition (trauma, surgery, serious injuries or illness, or medication), it is called ogilvie’s syndrome.Imaging of the Intestines (Ogilvie’s syndromeOgilvie’s syndromeA type of ileus, a functional not mechanical obstruction of the intestines. This syndrome is caused by a large number of disorders involving the smooth muscles or the nervous system.Large Bowel Obstruction)
  • Severe systemic illness
  • Surgery (most commonly from cesarean section or hip surgery)
  • Trauma
  • Spinal anesthesiaSpinal anesthesiaProcedure in which an anesthetic is injected directly into the spinal cord.Anesthesiology: History and Basic Concepts
  • Medications
    • OpiatesOpiatesOpiates are drugs that are derived from the sap of the opium poppy. Opiates have been used since antiquity for the relief of acute severe pain. Opioids are synthetic opiates with properties that are substantially similar to those of opiates.Opioid Analgesics
    • AnticholinergicsAnticholinergicsAnticholinergic drugs block the effect of the neurotransmitter acetylcholine at the muscarinic receptors in the central and peripheral nervous systems. Anticholinergic agents inhibit the parasympathetic nervous system, resulting in effects on the smooth muscle in the respiratory tract, vascular system, urinary tract, GI tract, and pupils of the eyes.Anticholinergic Drugs
    • CalciumCalciumA basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Electrolytes channel blockers

Etiology of chronic megacolon

• Congenital aganglionic megacolon (Hirschsprung’s disease)
  • Most cases associated with mutations in theRET proto-oncogene
  • Sometimes associated with other genetic syndromes:
    • Down’s syndrome
    • Multiple endocrine neoplasiaMultiple endocrine neoplasiaMultiple endocrine neoplasia syndromes are autosomal dominant inherited conditions characterized by 2 or more hormone-producing tumors involving the endocrine organs. There are different types of MEN, namely MEN1-4.Multiple Endocrine Neoplasia (MEN) type 2A or 2B
    • Waardenburg syndromeWaardenburg syndromeRare, autosomal dominant disease with variable penetrance and several known clinical types. Characteristics may include depigmentation of the hair and skin, congenital deafness, heterochromia iridis, medial eyebrow hyperplasia, hypertrophy of the nasal root, and especially dystopia canthorum. The underlying cause may be defective development of the neural crest (neurocristopathy). Waardenburg’s syndrome may be closely related to piebaldism. Klein-waardenburg syndrome refers to a disorder that also includes upper limb abnormalities.Hirschsprung Disease
• Acquired 
  • ChronicidiopathicIdiopathicDermatomyositisconstipationConstipationConstipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency< 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic.Constipation (most common)
  • NeuropathiesNeuropathiesChédiak-Higashi Syndrome
    • Diabetic
    • Spinal cordSpinal cordThe spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons).Spinal Cord: Anatomy injury
    • Parkinson’s disease
    • Chagas diseaseChagas diseaseInfection with the protozoan parasite trypanosoma cruzi, a form of trypanosomiasis endemic in central and south america. It is named after the brazilian physician carlos chagas, who discovered the parasite. Infection by the parasite (positive serologic result only) is distinguished from the clinical manifestations that develop years later, such as destruction of parasympathetic ganglia; chagas cardiomyopathy; and dysfunction of the esophagus or colon.Trypanosoma cruzi/Chagas disease (through destruction of entericneuronsNeuronsThe basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the nervous system.Nervous System: Histology)
  • Myopathies: Duchennemuscular dystrophyMuscular DystrophyBecker Muscular Dystrophy
  • Rheumatologic disorders
    • SclerodermaSclerodermaScleroderma (systemic sclerosis) is an autoimmune condition characterized by diffuse collagen deposition and fibrosis. The clinical presentation varies from limited skin involvement to diffuse involvement of internal organs.Scleroderma
    • Systemic lupus erythematosusSystemic lupus erythematosusSystemic lupus erythematosus (SLE) is a chronic autoimmune, inflammatory condition that causes immune-complex deposition in organs, resulting in systemic manifestations. Women, particularly those of African American descent, are more commonly affected.Systemic Lupus Erythematosus
    • DermatomyositisDermatomyositisA subacute or chronic inflammatory disease of muscle and skin, marked by proximal muscle weakness and a characteristic skin rash. The illness occurs with approximately equal frequency in children and adults. The skin lesions usually take the form of a purplish rash (or less often an exfoliative dermatitis) involving the nose, cheeks, forehead, upper trunk, and arms. The disease is associated with a complement mediated intramuscular microangiopathy, leading to loss of capillaries, muscle ischemia, muscle-fiber necrosis, and perifascicular atrophy. The childhood form of this disease tends to evolve into a systemic vasculitis. Dermatomyositis may occur in association with malignant neoplasms.Paraneoplastic Syndromes andpolymyositisPolymyositisPolymyositis (PM) is an autoimmune inflammatory myopathy caused by T cell-mediated muscle injury. The etiology of PM is unclear, but there are several genetic and environmental associations. Polymyositis is most common in middle-aged women and rarely affects children.Polymyositis

Pathophysiology

Toxic megacolon

• MucosalinflammationInflammationInflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function.Inflammation:
  • Causes the release of inflammatory mediators → induction ofnitric oxideNitric OxideA free radical gas produced endogenously by a variety of mammalian cells, synthesized from arginine by nitric oxide synthase. Nitric oxide is one of the endothelium-dependent relaxing factors released by the vascular endothelium and mediates vasodilation. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic guanylate cyclase and thus elevates intracellular levels of cyclic gmp.Pulmonary Hypertension Drugs synthase →nitric oxideNitric OxideA free radical gas produced endogenously by a variety of mammalian cells, synthesized from arginine by nitric oxide synthase. Nitric oxide is one of the endothelium-dependent relaxing factors released by the vascular endothelium and mediates vasodilation. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic guanylate cyclase and thus elevates intracellular levels of cyclic gmp.Pulmonary Hypertension Drugs generation bymacrophagesMacrophagesThe relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes. Main types are peritoneal macrophages; alveolar macrophages; histiocytes; kupffer cells of the liver; and osteoclasts. They may further differentiate within chronic inflammatory lesions to epithelioid cells or may fuse to form foreign body giant cells or langhans giant cells.Innate Immunity: Phagocytes and Antigen Presentation and smooth muscle cells → smooth muscle relaxation →colonColonThe large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.Colon, Cecum, and Appendix: Anatomy dilation
  • Extends to the smooth muscle layer → paralysis of smooth muscle →colonColonThe large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.Colon, Cecum, and Appendix: Anatomy dilation
• Potential precipitating factors:
  • HypokalemiaHypokalemiaHypokalemia is defined as plasma potassium (K+) concentration< 3.5 mEq/L. Homeostatic mechanisms maintain plasma concentration between 3.5-5.2 mEq/L despite marked variation in dietary intake. Hypokalemia can be due to renal losses, GI losses, transcellular shifts, or poor dietary intake.Hypokalemia
  • Medications:
    • OpiatesOpiatesOpiates are drugs that are derived from the sap of the opium poppy. Opiates have been used since antiquity for the relief of acute severe pain. Opioids are synthetic opiates with properties that are substantially similar to those of opiates.Opioid Analgesics
    • AnticholinergicsAnticholinergicsAnticholinergic drugs block the effect of the neurotransmitter acetylcholine at the muscarinic receptors in the central and peripheral nervous systems. Anticholinergic agents inhibit the parasympathetic nervous system, resulting in effects on the smooth muscle in the respiratory tract, vascular system, urinary tract, GI tract, and pupils of the eyes.Anticholinergic Drugs
    • Antidepressants
    • Bowel preparation solutions or barium
  • Abrupt discontinuation ofsteroidsSteroidsA group of polycyclic compounds closely related biochemically to terpenes. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (sterols), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus.Benign Liver Tumors or mesalamine in IBD

Acutecolonic pseudo-obstructionColonic pseudo-obstructionFunctional obstruction of the colon leading to megacolon in the absence of obvious colonic diseases or mechanical obstruction. When this condition is acquired, acute, and coexisting with another medical condition (trauma, surgery, serious injuries or illness, or medication), it is called ogilvie’s syndrome.Imaging of the Intestines

• Exact mechanism is unknown.
• Impairment of parasympathetic fibersS2S2Heart Sounds–S4S4Heart Sounds has been implicated.
• Progressive distention and ↑ tension on the colonic wall

Congenital aganglionic megacolon

• Failure ofneural crestNeural crestThe two longitudinal ridges along the primitive streak appearing near the end of gastrulation during development of nervous system (neurulation). The ridges are formed by folding of neural plate. Between the ridges is a neural groove which deepens as the fold become elevated. When the folds meet at midline, the groove becomes a closed tube, the neural tube.Hirschsprung Disease cell migration during the embryonic intestinal development → distalcolonColonThe large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.Colon, Cecum, and Appendix: Anatomy is aganglionic and nonfunctioning → distension of thecolonColonThe large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.Colon, Cecum, and Appendix: Anatomy proximal to the aganglionic segment
• Nerve plexuses affected:
  • Meissner (submucosal plexus)
  • Auerbach (myenteric plexusMyenteric plexusOne of two ganglionated neural networks which together form the enteric nervous system. The myenteric (Auerbach’s) plexus is located between the longitudinal and circular muscle layers of the gut. Its neurons project to the circular muscle, to other myenteric ganglia, to submucosal ganglia, or directly to the epithelium, and play an important role in regulating and patterning gut motility.Gastrointestinal Neural and Hormonal Signaling)
• The amount ofcolonColonThe large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.Colon, Cecum, and Appendix: Anatomy affected varies.

Chronic acquired megacolon

• Incompletely understood
• Neurologic or muscular dysfunction → disruption in normalperistalsisPeristalsisA movement, caused by sequential muscle contraction, that pushes the contents of the intestines or other tubular organs in one direction.Gastrointestinal Motility → progressivecolonColonThe large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.Colon, Cecum, and Appendix: Anatomy dilation
• Megacolon and megarectum from chronicconstipationConstipationConstipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency< 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic.Constipation is associated with:
  • ↑ rectalcomplianceComplianceDistensibility measure of a chamber such as the lungs (lung compliance) or bladder. Compliance is expressed as a change in volume per unit change in pressure.Veins: Histology andelasticityElasticityResistance and recovery from distortion of shape.Skeletal Muscle Contraction
  • Blunted rectal sensation
  • ↑thresholdThresholdMinimum voltage necessary to generate an action potential (an all-or-none response)Skeletal Muscle Contraction of analsphincter relaxationSphincter relaxationGastrointestinal Motility

Clinical Presentation

Symptoms

• Common symptoms:
  • Abdominal distention
  • ObstipationObstipationLarge Bowel Obstruction
• Toxic megacolon:
  • Bloody diarrheaBloody diarrheaDiarrhea (most common)
  • Sudden cessation ofdiarrheaDiarrheaDiarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation.Diarrhea should also be concerning.
  • Abdominal painAbdominal PainAcute Abdomen
  • MalaiseMalaiseTick-borne Encephalitis Virus
• Congenital aganglionic megacolon:
  • Majority will present in the neonatal period.
  • Bilious emesis
  • Failure to passmeconiumMeconiumThe thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the intestinal glands; bile pigments; fatty acids; amniotic fluid; and intrauterine debris. It constitutes the first stools passed by a newborn.Prenatal and Postnatal Physiology of the Neonate or stool
  • Feeding intolerance andfailure to thriveFailure to ThriveFailure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common.Failure to Thrive

Physical exam

• Common findings:
  • Abdominal distension
  • Tympanic abdomen
• Toxic megacolon:
  • TachycardiaTachycardiaAbnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia.Sepsis in Children
  • FeverFeverFever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin.Fever 
  • HypotensionHypotensionHypotension is defined as low blood pressure, specifically< 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause.Hypotension
  • Altered mental statusAltered Mental StatusSepsis in Children
  • Abdominal distension
  • Lower abdominal tenderness
  • Possible evidence ofperitonitisPeritonitisInflammation of the peritoneum lining the abdominal cavity as the result of infectious, autoimmune, or chemical processes. Primary peritonitis is due to infection of the peritoneal cavity via hematogenous or lymphatic spread and without intra-abdominal source. Secondary peritonitis arises from the abdominal cavity itself through rupture or abscess of intra-abdominal organs.Penetrating Abdominal Injury
    • Diffuse abdominal tenderness
    • Rebound tendernessRebound TendernessAcute Abdomen
    • Rigidity
• Congenital aganglionic megacolon:
  • Tight anal sphincter
  • Release of stool and gas with digital examination

Diagnosis

Laboratory evaluation

These studies help evaluate the severity of the disease, complications, and potential causes.

• General findings:
  • HypokalemiaHypokalemiaHypokalemia is defined as plasma potassium (K+) concentration< 3.5 mEq/L. Homeostatic mechanisms maintain plasma concentration between 3.5-5.2 mEq/L despite marked variation in dietary intake. Hypokalemia can be due to renal losses, GI losses, transcellular shifts, or poor dietary intake.Hypokalemia (gastrointestinal loss)
  • MetabolicalkalosisAlkalosisA pathological condition that removes acid or adds base to the body fluids.Respiratory Alkalosis (dehydrationDehydrationThe condition that results from excessive loss of water from a living organism.Volume Depletion and Dehydration)
  • MetabolicacidosisAcidosisA pathologic condition of acid accumulation or depletion of base in the body. The two main types are respiratory acidosis and metabolic acidosis, due to metabolic acid build up.Respiratory Acidosis and ↑ lactic acid are concerning for colonicischemiaIschemiaA hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation.Ischemic Cell Damage.
  • ↑ bloodureaUreaA compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.Urea CyclenitrogenNitrogenAn element with the atomic symbol n, atomic number 7, and atomic weight [14. 00643; 14. 00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth’s atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.Urea Cycle (BUN):creatinine ratio (dehydrationDehydrationThe condition that results from excessive loss of water from a living organism.Volume Depletion and Dehydration)
• Findings in toxic megacolon:
  • Complete blood count (CBC):
    • LeukocytosisLeukocytosisA transient increase in the number of leukocytes in a body fluid.West Nile Virus withleft shiftLeft ShiftYersinia pestis/Plague
    • AnemiaAnemiaAnemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology.Anemia: Overview and Types (due to gastrointestinal blood loss)
  • ↑erythrocyte sedimentation rateErythrocyte Sedimentation RateSoft Tissue Abscess (ESRESRSoft Tissue Abscess) and C-reactive protein (CRP)
  • Stool studies:
    • Culture forbacteriaBacteriaBacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases.Bacteriology and parasites
    • C.difficiletoxin

Imaging

• AbdominalX-rayX-rayPenetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source.Pulmonary Function Tests 
  • ColonColonThe large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.Colon, Cecum, and Appendix: Anatomy dilatation (> 6 cm)
  • Significant stool retention may be seen.
  • May showtransition zoneTransition ZonePediatric Gastrointestinal Abnormalities between dilatedcolonColonThe large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.Colon, Cecum, and Appendix: Anatomy and narrowrectumRectumThe rectum and anal canal are the most terminal parts of the lower GI tract/large intestine that form a functional unit and control defecation. Fecal continence is maintained by several important anatomic structures including rectal folds, anal valves, the sling-like puborectalis muscle, and internal and external anal sphincters.Rectum and Anal Canal: Anatomy in Hirschsprung’s disease
  • Air-fluid levels can be present.
  • Toxic megacolon findings:
    • Right andtransverse colonTransverse colonThe segment of large intestine between ascending colon and descending colon. It passes from the right colic flexure across the abdomen, then turns sharply at the left colonic flexure into the descending colon.Colon, Cecum, and Appendix: Anatomy dilation are the most prominent.
    • Loss of normal haustral pattern
    • Mucosal ulcerations
• Computed tomography (CT) with oral and intravenous (IV) contrast
  • Colonic dilatation (> 6 cm)
  • Free air indicatesperforationPerforationA pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force.Esophagitis.
  • May show fecal impaction or stool burden in cases associated with chronicconstipationConstipationConstipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency< 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic.Constipation
  • Toxic megacolon:
    • Loss of haustral pattern
    • Segmental colonic wall thinning
    • Nodular pseudopolyps (deep mucosal ulcerations)
    • IschemiaIschemiaA hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation.Ischemic Cell Damage (if present)
• Colonic transit studies
  • Assesses colonicmotilityMotilityThe motor activity of the gastrointestinal tract.Gastrointestinal Motility in chronic megacolon
  • Options:
    • RadiopaqueRadiopaqueAn object of high density that blocks X-rays (looks white)X-rays marker study
    • WirelessmotilityMotilityThe motor activity of the gastrointestinal tract.Gastrointestinal MotilitycapsuleCapsuleAn envelope of loose gel surrounding a bacterial cell which is associated with the virulence of pathogenic bacteria. Some capsules have a well-defined border, whereas others form a slime layer that trails off into the medium. Most capsules consist of relatively simple polysaccharides but there are some bacteria whose capsules are made of polypeptides.Bacteroides

Other studies

• EndoscopyEndoscopyProcedures of applying endoscopes for disease diagnosis and treatment. Endoscopy involves passing an optical instrument through a small incision in the skin i.e., percutaneous; or through a natural orifice and along natural body pathways such as the digestive tract; and/or through an incision in the wall of a tubular structure or organ, i.e. Transluminal, to examine or perform surgery on the interior parts of the body.Gastroesophageal Reflux Disease (GERD) 
  • For toxic megacolon:
    • CompletecolonoscopyColonoscopyEndoscopic examination, therapy or surgery of the luminal surface of the colon.Colorectal Cancer Screening is avoided due to the high risk ofperforationPerforationA pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force.Esophagitis
    • LimitedsigmoidoscopySigmoidoscopyEndoscopic examination, therapy or surgery of the sigmoid flexure.Colorectal Cancer Screening may help establish an underlying etiology (C. difficile CMV, IBD)
  • For chronic megacolon:
    • ColonoscopyColonoscopyEndoscopic examination, therapy or surgery of the luminal surface of the colon.Colorectal Cancer Screening can rule out obstruction.
    • BiopsyBiopsyRemoval and pathologic examination of specimens from the living body.Ewing Sarcoma can be performed if the etiology is unknown.
• Studies for Hirschsprung’s disease:
  • RectalbiopsyBiopsyRemoval and pathologic examination of specimens from the living body.Ewing Sarcoma
    • Gold standard
    • Absence ofganglion cellsGanglion CellsThe Visual Pathway and Related Disorders
  • Anorectal manometryAnorectal ManometryPediatric Constipation
    • Lack of internal analsphincter relaxationSphincter relaxationGastrointestinal Motility with rectal balloon dilation
    • Less accurate in neonates and people with chronicconstipationConstipationConstipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency< 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic.Constipation
  • Contrast enema:transition zoneTransition ZonePediatric Gastrointestinal Abnormalities between narrowedrectumRectumThe rectum and anal canal are the most terminal parts of the lower GI tract/large intestine that form a functional unit and control defecation. Fecal continence is maintained by several important anatomic structures including rectal folds, anal valves, the sling-like puborectalis muscle, and internal and external anal sphincters.Rectum and Anal Canal: Anatomy and proximal dilatedcolonColonThe large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.Colon, Cecum, and Appendix: Anatomy

Diagnostic criteria for toxic megacolon

• Radiographic evidence ofcolonColonThe large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.Colon, Cecum, and Appendix: Anatomy distension
• And ≥ 3 of the following:
  • FeverFeverFever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin.Fever
  • TachycardiaTachycardiaAbnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia.Sepsis in Children
  • LeukocytosisLeukocytosisA transient increase in the number of leukocytes in a body fluid.West Nile Virus
  • AnemiaAnemiaAnemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology.Anemia: Overview and Types
• And ≥ 1 of the following:
  • DehydrationDehydrationThe condition that results from excessive loss of water from a living organism.Volume Depletion and Dehydration
  • Altered mental statusAltered Mental StatusSepsis in Children
  • Electrolyte abnormalities
  • HypotensionHypotensionHypotension is defined as low blood pressure, specifically< 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause.Hypotension

Management

Toxic megacolon

• General management:
  • PatientsPatientsIndividuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures.Clinician–Patient Relationship should be monitored in an intensive care unit (ICUICUHospital units providing continuous surveillance and care to acutely ill patients.West Nile Virus).
  • Serial abdominal exams
  • Laboratory studies andabdominal X-raysAbdominal X-RaysX-rays every 12 hours 
  • NPO (nothing by mouth)
  • IV hydrationIv HydrationCrush Syndrome and electrolyte replacement
  • Nasogastric decompression, ifvomitingVomitingThe forcible expulsion of the contents of the stomach through the mouth.Hypokalemia or smallbowel dilatationBowel DilatationCongenital Duodenal Obstruction is present
  • Discontinue any antimotility,opiatesOpiatesOpiates are drugs that are derived from the sap of the opium poppy. Opiates have been used since antiquity for the relief of acute severe pain. Opioids are synthetic opiates with properties that are substantially similar to those of opiates.Opioid Analgesics, oranticholinergicAnticholinergicAnticholinergic drugs block the effect of the neurotransmitter acetylcholine at the muscarinic receptors in the central and peripheral nervous systems. Anticholinergic agents inhibit the parasympathetic nervous system, resulting in effects on the smooth muscle in the respiratory tract, vascular system, urinary tract, GI tract, and pupils of the eyes.Anticholinergic Drugs medications.
  • IVbroad-spectrumBroad-SpectrumFluoroquinolones antibiotics
    • Reduce septic complications
    • Cover for potentialperitonitisPeritonitisInflammation of the peritoneum lining the abdominal cavity as the result of infectious, autoimmune, or chemical processes. Primary peritonitis is due to infection of the peritoneal cavity via hematogenous or lymphatic spread and without intra-abdominal source. Secondary peritonitis arises from the abdominal cavity itself through rupture or abscess of intra-abdominal organs.Penetrating Abdominal Injury fromperforationPerforationA pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force.Esophagitis
• Address the specific cause:
  • C.difficilecolitisColitisInflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever.Pseudomembranous Colitis:
    • OralvancomycinVancomycinAntibacterial obtained from streptomyces orientalis. It is a glycopeptide related to ristocetin that inhibits bacterial cell wall assembly and is toxic to kidneys and the inner ear.Glycopeptides +metronidazoleMetronidazoleA nitroimidazole used to treat amebiasis; vaginitis; trichomonas infections; giardiasis; anaerobic bacteria; and treponemal infections.Pyogenic Liver Abscess (oral or intravenous)
    • VancomycinVancomycinAntibacterial obtained from streptomyces orientalis. It is a glycopeptide related to ristocetin that inhibits bacterial cell wall assembly and is toxic to kidneys and the inner ear.Glycopeptides enemas (can causeperforationPerforationA pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force.Esophagitis)
    • Fecal transplant
  • IBD:
    • IntravenousglucocorticoidsGlucocorticoidsGlucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs.Glucocorticoids
    • InfliximabInfliximabA chimeric monoclonal antibody to tnf-alpha that is used in the treatment of rheumatoid arthritis; ankylosing spondylitis; psoriatic arthritis and Crohn’s disease.Disease-Modifying Antirheumatic Drugs (DMARDs) orcyclosporineCyclosporineA cyclic undecapeptide from an extract of soil fungi. It is a powerful immunosupressant with a specific action on T-lymphocytes. It is used for the prophylaxis of graft rejection in organ and tissue transplantation.Immunosuppressants (2nd-line)
• Surgical management:
  • Indications:
    • If no clinical improvement within 48–72 hours
    • PerforationPerforationA pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force.Esophagitis
    • PeritonitisPeritonitisInflammation of the peritoneum lining the abdominal cavity as the result of infectious, autoimmune, or chemical processes. Primary peritonitis is due to infection of the peritoneal cavity via hematogenous or lymphatic spread and without intra-abdominal source. Secondary peritonitis arises from the abdominal cavity itself through rupture or abscess of intra-abdominal organs.Penetrating Abdominal Injury or worsening abdominal exam
    • Worsening colonic distention
    • IschemiaIschemiaA hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation.Ischemic Cell Damage ornecrosisNecrosisThe death of cells in an organ or tissue due to disease, injury or failure of the blood supply.Ischemic Cell Damage
    • Massive colonic hemorrhage
    • Worsening systemictoxicityToxicityDosage Calculation (feverFeverFever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin.Fever,hemodynamicsHemodynamicsThe movement and the forces involved in the movement of the blood through the cardiovascular system.Vascular Resistance, Flow, and Mean Arterial Pressure, or mental status)
    • Abdominal compartment syndromeAbdominal Compartment SyndromeAcute Pancreatitis or abdominalhypertensionHypertensionHypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter.Hypertension
  • Procedures:
    • Preferred in IBD: subtotal colectomy with end-ileostomy
    • Preferred inC.difficile:
      • Subtotal colectomy with end-ileostomy
      • Diverting loopileostomyIleostomySurgical creation of an external opening into the ileum for fecal diversion or drainage. This replacement for the rectum is usually created in patients with severe inflammatory bowel diseases. Loop (continent) or tube (incontinent) procedures are most often employed.Large Bowel Obstruction with colonic lavage

Acutecolonic pseudo-obstructionColonic pseudo-obstructionFunctional obstruction of the colon leading to megacolon in the absence of obvious colonic diseases or mechanical obstruction. When this condition is acquired, acute, and coexisting with another medical condition (trauma, surgery, serious injuries or illness, or medication), it is called ogilvie’s syndrome.Imaging of the Intestines

• Initial management(forstable patientsStable PatientsBlunt Chest Trauma withoutperitonitisPeritonitisInflammation of the peritoneum lining the abdominal cavity as the result of infectious, autoimmune, or chemical processes. Primary peritonitis is due to infection of the peritoneal cavity via hematogenous or lymphatic spread and without intra-abdominal source. Secondary peritonitis arises from the abdominal cavity itself through rupture or abscess of intra-abdominal organs.Penetrating Abdominal Injury in 1st 48–72 hours and a cecal diameter < 12 cm):
  • Rectal tube for decompression
  • Stop offending medications (opiatesOpiatesOpiates are drugs that are derived from the sap of the opium poppy. Opiates have been used since antiquity for the relief of acute severe pain. Opioids are synthetic opiates with properties that are substantially similar to those of opiates.Opioid Analgesics,anticholinergicsAnticholinergicsAnticholinergic drugs block the effect of the neurotransmitter acetylcholine at the muscarinic receptors in the central and peripheral nervous systems. Anticholinergic agents inhibit the parasympathetic nervous system, resulting in effects on the smooth muscle in the respiratory tract, vascular system, urinary tract, GI tract, and pupils of the eyes.Anticholinergic Drugs,calciumCalciumA basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Electrolytes channel blockers).
  • Treat underlying illness.
  • Follow with serial physical exams andX-raysX-raysX-rays are high-energy particles of electromagnetic radiation used in the medical field for the generation of anatomical images. X-rays are projected through the body of a patient and onto a film, and this technique is called conventional or projectional radiography.X-rays every 12–24 hours.
• Pharmacologic interventions:
  • Indications:
    • No improvement in 72 hours
    • Cecal diameter > 12 cm
  • IVneostigmineNeostigmineA cholinesterase inhibitor used in the treatment of myasthenia gravis and to reverse the effects of muscle relaxants such as gallamine and tubocurarine. Neostigmine, unlike physostigmine, does not cross the blood-brain barrier.Cholinomimetic Drugs(acetylcholinesterase inhibitor):
    • Bolus dosing or continuous infusion
    • 89% respond to a single dose.
    • PatientsPatientsIndividuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures.Clinician–Patient Relationship need to be in a monitored setting.
  • MethylnaltrexoneMethylnaltrexoneOpioid Analgesics: if the obstruction is precipitated byopiatesOpiatesOpiates are drugs that are derived from the sap of the opium poppy. Opiates have been used since antiquity for the relief of acute severe pain. Opioids are synthetic opiates with properties that are substantially similar to those of opiates.Opioid Analgesics
• Colonoscopic decompression:
  • Indications:
    • No response toneostigmineNeostigmineA cholinesterase inhibitor used in the treatment of myasthenia gravis and to reverse the effects of muscle relaxants such as gallamine and tubocurarine. Neostigmine, unlike physostigmine, does not cross the blood-brain barrier.Cholinomimetic Drugs
    • ContraindicationsContraindicationsA condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks).Noninvasive Ventilation toneostigmineNeostigmineA cholinesterase inhibitor used in the treatment of myasthenia gravis and to reverse the effects of muscle relaxants such as gallamine and tubocurarine. Neostigmine, unlike physostigmine, does not cross the blood-brain barrier.Cholinomimetic Drugs
  • Has a 3%perforationPerforationA pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force.Esophagitis rate
• Surgery:
  • Indications:
    • Failure of non-surgical management
    • PeritonitisPeritonitisInflammation of the peritoneum lining the abdominal cavity as the result of infectious, autoimmune, or chemical processes. Primary peritonitis is due to infection of the peritoneal cavity via hematogenous or lymphatic spread and without intra-abdominal source. Secondary peritonitis arises from the abdominal cavity itself through rupture or abscess of intra-abdominal organs.Penetrating Abdominal Injury (ischemiaIschemiaA hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation.Ischemic Cell Damage orperforationPerforationA pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force.Esophagitis)
  • Procedures:
    • Primary anastomosis (stable patientsStable PatientsBlunt Chest Trauma)
    • Total abdominal colectomy with endileostomyIleostomySurgical creation of an external opening into the ileum for fecal diversion or drainage. This replacement for the rectum is usually created in patients with severe inflammatory bowel diseases. Loop (continent) or tube (incontinent) procedures are most often employed.Large Bowel Obstruction (ischemiaIschemiaA hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation.Ischemic Cell Damage orperforationPerforationA pathological hole in an organ, blood vessel or other soft part of the body, occurring in the absence of external force.Esophagitis)

Chronic megacolon

• General management:
  • Supportive treatment as needed (hydration, electrolyte correction)
  • Stop offending medications (opiatesOpiatesOpiates are drugs that are derived from the sap of the opium poppy. Opiates have been used since antiquity for the relief of acute severe pain. Opioids are synthetic opiates with properties that are substantially similar to those of opiates.Opioid Analgesics,anticholinergicsAnticholinergicsAnticholinergic drugs block the effect of the neurotransmitter acetylcholine at the muscarinic receptors in the central and peripheral nervous systems. Anticholinergic agents inhibit the parasympathetic nervous system, resulting in effects on the smooth muscle in the respiratory tract, vascular system, urinary tract, GI tract, and pupils of the eyes.Anticholinergic Drugs).
  • Nasogastric or rectal tube decompression, if requiringhospitalizationHospitalizationThe confinement of a patient in a hospital.Delirium
  • Empty the bowel.
    • Manual disimpaction may be required for fecal impaction.
    • Osmotic laxativesOsmotic LaxativesLaxatives
    • SuppositoriesSuppositoriesMedicated dosage forms that are designed to be inserted into the rectal, vaginal, or urethral orifice of the body for absorption. Generally, the active ingredients are packaged in dosage forms containing fatty bases such as cocoa butter, hydrogenated oil, or glycerogelatin that are solid at room temperature but melt or dissolve at body temperature.Large Bowel Obstruction
    • Enemas 
  • Strict bowel retraining program
    • ScheduleddefecationDefecationThe normal process of elimination of fecal material from the rectum.Gastrointestinal Motility times
    • Increase physical activity.
    • Consume bulking agents (high fiber).
• Surgical management:
  • For severe cases that are unresponsive to medical management
  • Hirschsprung’s disease:
    • Definitive therapy
    • Resection of aganglionic segment with primary anastomosis

Differential Diagnosis

• Mechanical largebowel obstructionBowel obstructionAny impairment, arrest, or reversal of the normal flow of intestinal contents toward the anal canal.Ascaris/Ascariasis:interruption in theflowFlowBlood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls.Vascular Resistance, Flow, and Mean Arterial Pressure of intraluminal contents caused by intrinsic or extrinsiccompressionCompressionBlunt Chest Trauma of the colonic lumen. Common etiologies includecolorectal cancerColorectal cancerColorectal cancer (CRC) is the 2nd leading cause of cancer-related deaths in the United States. Colorectal cancer is a heterogeneous disease that arises from genetic and epigenetic abnormalities, with influence from environmental factors.Colorectal Cancer andvolvulusVolvulusA volvulus is the twisting or axial rotation of a portion of the bowel around its mesentery. The most common site of volvulus in adults is the colon; most frequently the sigmoid volvulus. Patients typically present with symptoms of bowel obstruction such as abdominal pain, distension, vomiting, and constipation/obstipation.Volvulus.PatientsPatientsIndividuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures.Clinician–Patient Relationship present with abdominal distention,obstipationObstipationLarge Bowel Obstruction,nauseaNauseaAn unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses.Antiemetics, andvomitingVomitingThe forcible expulsion of the contents of the stomach through the mouth.Hypokalemia. The diagnosis is established with imaging. Management includes bowel rest, decompression, and surgery.
• Smallbowel obstructionBowel obstructionAny impairment, arrest, or reversal of the normal flow of intestinal contents toward the anal canal.Ascaris/Ascariasis: an interruption of intraluminal contents through thesmall bowelSmall bowelThe small intestine is the longest part of the GI tract, extending from the pyloric orifice of the stomach to the ileocecal junction. The small intestine is the major organ responsible for chemical digestion and absorption of nutrients. It is divided into 3 segments: the duodenum, the jejunum, and the ileum.Small Intestine: Anatomy due to a mechanical or functional problem.PatientsPatientsIndividuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures.Clinician–Patient Relationship present withabdominal painAbdominal PainAcute Abdomen, distention,nauseaNauseaAn unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses.Antiemetics, andvomitingVomitingThe forcible expulsion of the contents of the stomach through the mouth.Hypokalemia. Imaging will show involvement of thesmall bowelSmall bowelThe small intestine is the longest part of the GI tract, extending from the pyloric orifice of the stomach to the ileocecal junction. The small intestine is the major organ responsible for chemical digestion and absorption of nutrients. It is divided into 3 segments: the duodenum, the jejunum, and the ileum.Small Intestine: Anatomy, although thecolonColonThe large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal.Colon, Cecum, and Appendix: Anatomy may also be distended in functional obstruction. Most cases will resolve with supportive care.
• AppendicitisAppendicitisAppendicitis is the acute inflammation of the vermiform appendix and the most common abdominal surgical emergency globally. The condition has a lifetime risk of 8%. Characteristic features include periumbilical abdominal pain that migrates to the right lower quadrant, fever, anorexia, nausea, and vomiting.Appendicitis:inflammationInflammationInflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function.Inflammation of theappendixAppendixA worm-like blind tube extension from the cecum.Colon, Cecum, and Appendix: Anatomy. EarlyappendicitisAppendicitisAppendicitis is the acute inflammation of the vermiform appendix and the most common abdominal surgical emergency globally. The condition has a lifetime risk of 8%. Characteristic features include periumbilical abdominal pain that migrates to the right lower quadrant, fever, anorexia, nausea, and vomiting.Appendicitis can present with diffuse colickypainPainAn unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons.Pain: Types and Pathways, butpainPainAn unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons.Pain: Types and Pathways and tenderness eventually localize to theright lower quadrantRight lower quadrantAnterior Abdominal Wall: Anatomy. Diagnosis is established by CT scan. Treatment includes antibiotics and surgery.
• DiverticulitisDiverticulitisInflammation of a diverticulum or diverticula.Diverticular Disease:inflammationInflammationInflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function.Inflammation of the colonic diverticula.PatientsPatientsIndividuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures.Clinician–Patient Relationship present with crampy lowerabdominal painAbdominal PainAcute Abdomen, and may haveconstipationConstipationConstipation is common and may be due to a variety of causes. Constipation is generally defined as bowel movement frequency< 3 times per week. Patients who are constipated often strain to pass hard stools. The condition is classified as primary (also known as idiopathic or functional constipation) or secondary, and as acute or chronic.Constipation.DiverticulitisDiverticulitisInflammation of a diverticulum or diverticula.Diverticular Disease is frequently associated withfeverFeverFever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin.Fever andleukocytosisLeukocytosisA transient increase in the number of leukocytes in a body fluid.West Nile Virus. A CT scan shows the characteristic inflammatory findings. Treatment includes bowel rest, antibiotics, and occasionally surgery.

References

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3. Wesson D.E., Esperanza Lopez M. (2025). Congenital aganglionic megacolon (Hirschsprung disease). Retrieved June 17, 2025, fromhttps://www.uptodate.com/contents/congenital-aganglionic-megacolon-hirschsprung-disease
4. Belkind‑Gerson, J. (2023).Hirschsprung disease (congenital megacolon). InMSD Manual Professional Version. Merck & Co., Inc. Retrieved June 17, 2025, fromhttps://www.msdmanuals.com/professional/pediatrics/congenital-gastrointestinal-anomalies/hirschsprung-disease
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