Patho Ch 30 Common Disorders of the Large Intestine – Flashcards
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Large Bowel Function
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-surface area is smooth -main function if the absorption of water and electrolytes, mainly sodium and chloride -sodium is actively absorbed, whereas chloride follows passively down an electrochemical gradient -water flows osmotically -sodium absorption occurs with potassium excretion
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Large Bowel Function Bacteria
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-normal flora bacteria - bacteroides, clostridia, anaerobic lactobacilli, and E. coli (most are anaerobes) - break down proteins that were not digested or absorbed in the small intestine -these resulting amino acids are broken down by bacteria, which leaves to ammonia -the ammonia is carried to the liver and converted to urea -bacteria converted unabsorbed carbohydrates into absorbable organic acids -bacteria metabolize bile salts and facilitate absorption of bile
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Constipation
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-common problem especially in elderly -problems occur when severe constipation causes fecal impaction and obstipation
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Fecal Impaction
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-occurs when hard stool that cannot be passed is lodged in the sigmoid colon and rectum -commonly a patient can develop liquid stools that pass around a fecal impaction
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Medications that Can Cause Decreased Intestinal Motility and Constipation
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-benzodiazepines -chemotherapy agents -diuretics -lithium salts -opiates -tricylic antidepressants
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Chronic Use of Laxatives
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-cathartic colon: the anatomical and physiological change in the colon that occurs with chronic use of stimulant laxatives -excessive laxative use is defined as more than 3 times per week for at least one year -signs an symptoms of cathartic colon include bloating, feeling of fullness, abdominal pain, and incomplete fecal evacuation -radiological studies show an atonic and redundant colon
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Assessment of Large Bowel Function
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-Interview questions -quality of pain, abdominal pain, cramping, nausea or vomiting, excessive gas, and rectal fullness -frequency, amount, timing, color -type of diet, use of laxatives or drugs -it is important to distinguish between complete bowel obstruction from partial obstruction
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Colicky Pain
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-crampy intense abdominal pain that occurs in waves -is often characteristic of large bowel disorders
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Acute Abdomen
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-an abdomen that is tender and showing signs of inflammation of the peritoneal membrane
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Signs of Acute Abdomen on Physical Examination
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-abdominal pain: waves of sharp constricting pain that take the breath away. pain is worsened by movement -involuntary guarding: the patient's abdominal muscles contract with palpation -abdominal rigidity: the abdomen is stiff to the touch -*rebound tenderness: when the examiner deeply palpates the abdomen, pain is felt by the patient as the examiner lifts his or her hand
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Diagnosis of Acute Abdomen
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-pain is a valuable diagnostic clue -location of pain can assist -opiates are often withheld until a diagnosis is made
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Important Aspects of Physical Examination of the Abdomen
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-percussion of tympany of gas-filled organs -RLQ tenderness: appendicitis -digital exam may demonstrate hard stool in the rectum with fecal impaction -LLQ tenderness: diverticulitis -URQ tenderness: Murphy's sign, which is commonly caused by cholecystitis, which is inflammation of the gallbladder -a stool sample may be obtained for fecal occult blood testing if melon is suspected -in female patients, a pelvic examination is needed to rule out a gynecological source of pain
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Hernia and Bowel Obstruction
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-evaluation of the inguinal and femoral regions should be an integral part of the examination in a patient with suspected large bowel obstruction -incarcerated hernias represent a frequently missed cause of bowel obstruction
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How to Detect Blood In Stool
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-FOBT or stoll guaiac test -accuracy is highest after completion of three tests at three different times -a chest x-ray can show free air under the diaphragm when there is perforation of the bowel or abdominal cavity -air under the diaphragm from perforation of the bowel commonly causes shoulder pain
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*Common Surgical Procedures Large Bowel
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-an ileostomy or colostomy is a reversible surgical procedure in which the healthy end of the intestine is brought out of the abdomen through an incision in the anterior abdominal wall -ileostomy, the ilium of the small intestine is surgically brought out to the exterior abdominal wall -colostomy, the colon is about out to the anterior abdomen -the opening is called a stoma, which allows for excretion of intestinal contents into an attached collection appliance -endoscopically placed expandable stents can be used to relieve large bowel obstructions
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Inflammatory Bowel Disease (IBD)
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-includes Cron's diseases, also called regional enteritis, and ulcerative colitis (UC) -both Crohn's disease and ulcerative colitis are chronic, incurable diseases that can occur at any age, but more prevalent in the young adult -both caused by autoimmune
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4 Aspects of Crohn's Disease
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-chronic TRANSMURAL inflammatory process of the bowel that often leads to fibrosis and obstructive symptoms and can affect any part of the gastrointestinal tract from the mouth to anus -most common location: terminal ileum and ascending right colon -skip lesions: are areas of disease separated by healthy areas -cobblestoning: bowel mucosa develops granulomas
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Toxic Megacolon
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-complication of Crohn's disease -extreme dilation of a segment of the diseased colon, commonly transverse colon -causes complete obstruction and impaired absorption of fluids and electrolytes -life threatening perforation and peritonitis can result
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Crohn's Disease Symptoms
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-diarrhea and abdominal pain -remissions and exacerbations -malabsorption of nutrients -lost electrolytes -anemia from loss of blood in stool -dehydration -abdominal tenderness -hyperactive bowel sounds -steady progressive weight loss -anorexia -nausea -vomitting -pallor -fever -intestinal obstruction
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Crohn's Disease Treatment
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-adequate fluids and a balanced diet, multivitamin supplement -antidiarrheals -bile acid sequestrates -immunosuppressives -corticosteroids -intestinal resection
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Ulcerative Colitis (UC)
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-solely involves the large intestine -can lead to colon cancer -peak occurs from 15-25 or 55-65 -autoimmune disorder -affects only the mucosal layer of the large bowel -continuous areas of the inflammation in the large intestine are involved -pseudopolyps: formation of inflammatory areas of protruding growths
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Ulcerative Colitis (UC) Symptoms
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-colicky abdominal pain -blood in stool -diarrhea -dehydration -malabsorption and weight loss -abdominal guarding -uveitis -gangrenosum and erythema nodosum -inflammation of liver and bile duct
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Ulcerative Colitis (UC) Treatment
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-similar to cronh's -corticosteroids -anti-inflammatory agents -antidiarrheal -rehydration -immunosuppresents -antibiotics -colostomy and ileostomy
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Large Bowel Obstruction (LBO)
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-inability of the intestinal contents to move through the large intestine Obstructions May Be -partial or complete -acute or chronic -reversible or irreversible -mechanical vs nonmechanical -majorly occurs in the sigmoid section of the bowel -high mortality rate if diagnosis and treatment are nor commenced within the first 24 hours
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Mechanical Large Bowel Obstruction
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-physically blocks movement of material through the intestines -may be caused by scar tissue from a prior surgery (adhesions), benign or malignant tumors, abdominal hernia, swallowed foreign body, gallstone that might migrate into the intestine, bolus of undigested food, intussusception, volvulus, stricture or diverticula
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Nonmechanical Large Bowel Obstruction
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-causes stem from disruption of peristalsis because of weakness of muscles of the intestinal wall (dysmotility syndrome or pseudo obstruction) or paralysis of the bowel wall (paralytic ileus) -in older individuals eyes can become hardened into a solid mass and obstruct the bowel (fecal impaction)
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Large Bowel Obstruction Signs and Symptoms
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-abdominal pain -abdominal distension -abdominal tenderness -abdominal rigidity -partial obstruction -> high - pitched bowel sounds -complete obstruction -> no bowel sounds, no feces in rectum
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Large Bowel Obstruction Diagnosis
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-abdominal x-ray; distended colon with loops of dilated bowel -if a perforation has occurred, free air is visualized under the diaphragm -serum amylase levels are elevated with perforation of the bowel or organ -CT scan -colonoscopy
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Large Bowel Obstruction Treatment
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-fluid replacement -prophylactic antibiotic therapy -intestinal decompression -surgical consultation
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Appendicitis
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-inflammation occurs in the vermiform appendix, a blind-ended, pouch like area that protrude from the cecum, where the small intestine meets the large intestine -most common cause of acute abdomen -if left untreated can rupture causing peritonitis
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Appendicitis Etiology
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-a nerarby blockage, commonly caused by stool or fecalith (calcified feces) -blockage of appendix often occurs when neighboring mesenteric lymph nodes become inflamed in response to a viral or bacterial infection and compress the appendix -abdominal trauma can initiate an inflammatory response that results in inflammation of the appendix -appendicitis can occur if the appendix becomes twisted or occlude by bowel adhesions
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Two Major Initiating Events for Appendicitis
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-narrowing of the appendix lumen caused by an obstruction that results in ischemia and a compromised blood supply to the region -development of a medium for bacterial growth as normal mucous secretions remain trapped behind the lumen because of narrowing and increase of intraluminal pressure and distension
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Appendicitis Signs and Symptoms
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-McBurney's Point: abdominal pain that originates in the umbilical region and radiates to the right lower quadrant -pain becomes more severe and localized as the appendix becomes more inflamed -fever -abdominal distension -rebound tenderness in the RLQ
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Appendicitis Time Period
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-1 to 3 days -important for females with abdominal pain to have pregnancy test and pelvic examination to rule out pregnancy
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Appendicitis Diagnosis
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-CT scan most accurate -abdominal ultrasound -x-ray -elevated c-reactive protein -elevated WBC count -high 5 - HIAA, breakdown product of serotonin may be evident in urine
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Appendicitis Surgery
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-avoid performing unnecessary surgery -10 to 15% negative appendectomy rate has been accepted in order to minimize the incidence or perforated appendicitis with its increased morbidity -mesenteric adenitis: swollen mesenteric lymph nodes, present with signs and symptoms exactly like appendicitis; patients undergo negative appendectomies
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Diverticulosis
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-no pain -the bowel wall has multiple weakened areas that form small outpouchings called diverticula -can collect intestinal contents and form a colonic obstruction -found in sigmoid and descending colon -often become inflames, at which point the condition becomes diverticulitis
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Etiology of Diverticular Disease Is Associated With Two Main Factors
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1. weakness of the bowel wall 2. increased intraluminal pressure -diverticulitis occurs when intestinal contents blocks the diverticulum, thus cutting off the blood supply and providing an environment conductive to the formation of infection *-most significant risk factor for diverticular formation is a diet low in fiber
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Diverticulitis Signs and Symptoms
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-pain, dull episodic, or steady left quadrant or mid abdominal pain, fever, and nausea -alterations in bowel habits, including constipation, diarrhea, anorexia -traces of occult blood may be found in the stool
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Diverticulitis Diagnosis
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-CT scan is the best -lower G series -colonoscopy
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Diverticulitis Treatment
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-opioids may be required for pain, but morphine should be avoided because it can cause colon spasms -dietary modifications -rest colon by NPO -total parenteral nutrition (TNP)
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Volvulus
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-twisting of the large intestine around a point of attachment in the abdomen -sigmoid volvulus is most common type found in adults -sigmoid colon is weighed down because of chronic constipation and a high fiber diet, this makes it most susceptible to volvulus -volvulus of the intestine results in bowel obstruction and ischemia of the bowel
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Symptoms of Volvulus
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-bilious vomiting -abdominal pain (colicky, then steady) -anorexia -blood and mucous in stool -abdominal tenderness -shock possible