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Appendicitis and Peritonitis

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					Appendicitis and Peritonitis
                The appendix
• a normal true diverticulum of the cecum that is prone to
  acute and chronic inflammation
• Acute appendicitis is most common in adolescents and
  young adults, but may occur in any age group
• The lifetime risk for appendicitis is 7%; males are
  affected slightly more often than females
• Despite the prevalence of acute appendicitis, the
  diagnosis can be difficult to confirm preoperatively and
  may be confused with mesenteric lymphadenitis, acute
  salpingitis, ectopic pregnancy, mittelschmerz and Meckel
  diverticulitis
       Appendicitis: Pathogenesis

• luminal obstruction, usually caused by a small stone-like
  mass of stool, or fecalith, or, less commonly, enlarged
  lymph node during infection, a gallstone, tumour, or
  mass of worms
• Luminal obstruction  Progressive increases in
  intraluminal pressure compromise venous outflow 
  ischemic injury
• Ischemic injury + stasis of luminal contents
   bacterial proliferation  inflammatory
  responses including tissue oedema and
  neutrophilic infiltration of the lumen, muscular
  wall, and periappendiceal soft tissues
        Appendicitis: Morphology
•   In early acute appendicitis subserosal vessels are congested and there is a
    modest perivascular neutrophilic infiltrate within all layers of the wall
•   The inflammatory reaction transforms the normal glistening serosa into a
    dull, granular, erythematous surface
•   Diagnosis of acute appendicitis requires neutrophilic infiltration of the
    muscularis propria. Although mucosal neutrophils and focal superficial
    ulceration are often present, these are not specific markers of acute
    appendicitis.
•   In severe cases a prominent neutrophilic exudate  serosal fibrinopurulent
    reaction
        focal abscesses may form within the wall (acute suppurative appendicitis)
        further appendiceal compromise areas of hemorrhagic ulceration and
       gangrenous necrosis that extends to the serosa (acute gangrenous
       appendicitis), which is often followed by rupture and suppurative peritonitis.
     Appendicitis: Clinical Features
CLASSIC Clinical Features
•  Vague, often colicky, periumbilical pain (or epigastric) that ultimately localizes to the right lower quadrant (occurs
   in only 66% of patients. However, in a male patient these symptoms are sufficient to advise surgical exploration.) \
•   Within 12 hours, pain shifts to right lower quadrant, with steady ache worsened by walking or coughing
•  nausea, vomiting, low-grade fever, and a mildly elevated peripheral white cell count
•  A classic physical finding is McBurney's sign, deep tenderness located two thirds of the distance from the
   umbilicus to the right anterior superior iliac spine (McBurney's point)
•   Localized tenderness with guarding in the right lower quadrant
•    Rebound tenderness

COMPLICATIONS
•  appendiceal perforation
•   If the process evolves slowly, adjacent organs such as the terminal ileum, cecum, and omentum may wall off the
   appendiceal area so that a localized abscess will develop
•  rupture of primary appendiceal abscesses may produce fistulas between the appendix and bladder, small
   intestine, sigmoid, or cecum
•  peritonitis
•  Pyelophlebitis (Septic thrombophlebitis (pylephlebitis) of the portal venous system
•  portal venous thrombosis
•  liver abscess
•  bacteremia

NOTE:
•  recurrent acute appendicitis does occur, often with complete resolution of inflammation and symptoms between
   attacks
•  Recurrent acute appendicitis may also occur if a long appendiceal stump is left after initial appendectomy.
         Tumors of the Appendix
• The most common tumour of the appendix is the carcinoid. It is
  usually discovered incidentally. Although intramural and transmural
  extension may be evident, nodal metastases are very infrequent,
  and distant spread is exceptionally rare
• Conventional adenomas or non-mucin-producing adenocarcinomas
  also occur in the appendix and may cause obstruction and
  enlargement that mimics acute appendicitis
• Mucocele, a dilated appendix filled with mucin, may simply
  represent an obstructed appendix containing inspissated mucin or
  be a consequence of mucinous cystadenoma or mucinous
  cystadenocarcinoma
• With cystadenocarcinoma, invasion through the appendiceal wall
  can lead to intraperitoneal seeding and spread. In the most
  advanced cases the abdomen fills with mucus and fibrosis , a
  condition called pseudomyxoma peritoneii
                          Peritonitis
•   Inflammation of the serosal membrane that lines the abdominal cavity
    and the organs contained therein

Bacterial peritonitis
• occurs when bacteria from the gastrointestinal lumen are released
  into the abdominal cavity, typically following perforation.
• occurs most commonly as a complication of acute appendicitis,
  peptic ulcer, cholecystitis, diverticulitis, and intestinal ischemia.
  Acute salpingitis, abdominal trauma, and peritoneal dialysis are
  other potential sources of contaminating bacteria.
• E. coli, streptococci, S. aureus, enterococci, and C. perfringens are
  implicated most often but virtually any bacteria can be associated
  with bacterial peritonitis.
    Clinical Presentation: Peritonitis
•    Acute peritonitis is most often infectious and is usually related to a perforated viscus
     (and called secondary peritonitis). When no intraabdominal source is identified,
     infectious peritonitis is called primary or spontaneous.

•    The cardinal manifestations of peritonitis are
      –    acute abdominal pain and tenderness, usually with fever
      –   The location of the pain depends on the underlying cause and whether the inflammation is
          localized or generalized.
      –   Rigidity of the abdominal wall is common in both localized and generalized peritonitis.
      –   Bowel sounds are usually absent.
      –   Tachycardia, hypotension, and signs of dehydration are common.
      –   Leukocytosis and marked acidosis are common laboratory findings.
      –   Plain abdominal films may show dilation of large and small bowel with oedema of the bowel
          wall. Free air under the diaphragm is associated with a perforated viscus. CT and/or
          ultrasonography can identify the presence of free fluid or an abscess. When ascites is
          present, diagnostic paracentesis with cell count (>250 neutrophils/ L is usual in peritonitis),
          protein and lactate dehydrogenase levels, and culture is essential. In elderly and
          immunosuppressed patients, signs of peritoneal irritation may be more difficult to detect.
           Peritoneum: Tumours
• Most tumors of the peritoneum are malignant and can be divided into
  primary and secondary forms.
• Primary tumors arising from peritoneal lining are mesotheliomas that
  are similar to tumors of the pleura and pericardium. Peritoneal
  mesotheliomas are almost always associated with significant asbestos
  exposure. It has been hypothesized that swallowed asbestos fibers
  somehow penetrate through the intestinal wall to reach the
  peritoneum.
• Secondary tumors of the peritoneum are quite common. In any form of
  advanced cancer, direct spread to the serosal surface or metastatic
  seeding (peritoneal carcinomatosis) may occur. The most common
  tumors producing diffuse serosal implants are ovarian and pancreatic
  adenocarcinoma. Appendiceal mucinous carcinomas may
  produce pseudomyxoma peritoneii. However, any intra-abdominal
  malignancy, as well as a wide variety of tumors of extra-abdominal
  origin, may spread to the peritoneum.
• Robbin’s
• Assess Med- Quick Answers

				
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posted:10/15/2011
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