1、Anatomy Varied anatomyLength: 510 cm, narrow lumenhaustra of colonEpidemiologyThe most common acute abdomen disease The incidence of appendectomy appears to be declining due to more accurate preoperative diagnosis.Despite newer imaging techniques, acute appendicitis can be very difficult to diagnose

2、. Pathophisiology Simple appendicitisSuppurative appendicitis Gangrenous appendicitisPerforated appendicitisPeritonitisAbscess around the appendixMucocele of appendixPathophysiologyAcute appendicitis is thought to begin with obstruction of the lumenObstruction can result from food matter, adhesions,

3、 or lymphoid hyperplasiaAppendix is twisted, and Lumen of appendix is narrow, result in obstructionMucosal secretions continue to increase intraluminal pressureEtiology 1. The anatomy characteristics2. The tissue features3. fecality, foreign body obstruction4. Parasites cause the mucosa damage5. adh

4、esion, pressure cause appendix distortedObstruction high pressure limph obstructed, ischemia mucosa damage bacteria invade（70%80%）Artery The appendix artery has no branches, is easily to be obstacled EtiologyEventually the pressure exceeds capillary perfusion pressure and venous and lymphatic draina

5、ge are obstructed.With vascular compromise, epithelial mucosa breaks down and bacterial invasion by bowel flora occurs.microbes：Ecoli, streptococcus, Pseudomonas, anaerobeEtiologyIncreased pressure also leads to arterial stasis and tissue infarctionEnd result is perforation and spillage of infected

6、appendiceal contents into the peritoneumPathophysiologyInitial luminal distention triggers visceral afferent pain fibers, which enter at the 10th thoracic vertebral level.This pain is generally vague and poorly localized.Pain is typically felt in the periumbilical or epigastric area.PathophysiologyA

7、s inflammation continues, the serosa and adjacent structures become inflamedThis triggers somatic pain fibers, innervating the peritoneal structuresTypically causing pain in the RLQPathophysiologyThe change in stimulation form visceral to somatic pain fibers explains the classic migration of pain in

8、 the periumbilical area to the RLQ seen with acute appendicitis.PathophysiologyExceptions exist in the classic presentation due to anatomic variability of the appendixAppendix can be retrocecal causing the pain to localize to the right flankIn pregnancy, the appendix can be shifted and patients can

9、present with RUQ painPathophysiologyIn some males, retroileal appendicitis can irritate the ureter and cause testicular pain.Pelvic appendix may irritate the bladder or rectum causing suprapubic pain, pain with urination, or feeling the need to defecateMultiple anatomic variations explain the diffic

10、ulty in diagnosing appendicitisManifestations Primary symptom: abdominal pain to 2/3 of patients have the classical presentationPain beginning in epigastrium or periumbilical area that is vague and hard to localize Manifestations As the illness progresses RLQ localization typically occursRLQ pain wa

11、s 81 % sensitive and 53% specific for diagnosisMigration of pain from initial periumbilical to RLQ was 64% sensitive and 82% specificManifestations Associated symptoms: indigestion, discomfort, flatus, need to defecate, anorexia, nausea, vomitingAnorexia is the most common of associated symptomsVomi

12、ting is more variable, occuring in about of patientsPhysical ExamFindings depend on duration of illness prior to exam.Early on patients may not have localized tendernessWith progression there is tenderness to deep palpation over McBurneys pointPhysical ExamRovsings sign: pain in RLQ with palpation t

13、o LLQObturator sign: passively flex the R hip and knee and internally rotate the hip. If there is increased pain then the sign is positivePhysical examPsoas sign: place patient in L lateral decubitus and extend R leg at the hip. If there is pain, the sign is positive.Rectal exam: pain can be most pr

14、onounced if the patient has pelvic appendixPhysical ExamAdditional components that may be helpful in diagnosis: rebound tenderness, voluntary guarding, muscular rigidity, tenderness on rectalFever: another late finding.At the onset of pain fever is usually not found. Temperatures 39 C are uncommon i

15、n first 24 h, but common after ruptureDiagnosisAcute appendicitis should be suspected in anyone with epigastric, periumbilical, right flank, or right sided abd pain who has not had an appendectomyWomen of child bearing age need a pelvic exam and a pregnancy test.Additional studies: CBC, UA, imaging

16、studiesDiagnosisThe WBC is of limited value. Sensitivity of an elevated WBC is 70-90%, but specificity is very low.But, +predictive value of high WBC is 92% and predictive value is 50%CRP and ESR have been studied with mixed resultsDiagnosisImaging studies: include X-rays, US, CTX rays of abd are ab

17、normal in 24-95%Abnormal findings include: fecalith, appendiceal gas, localized paralytic ileus, blurred right psoas, and free airAbdominal xrays have limited use:for the findings are seen in multiple other processesDiagnosisLimitations of US: retrocecal appendix may not be visualized, perforations

18、may be missed due to return to normal diameterDiagnosisCT: best choice based on availability and alternative diagnoses.In one study, CT had greater sensitivity, accuracy, -predictive value Special PopulationsVery young, very old, pregnant, and HIV patients present atypically and often have delayed d

19、iagnosisHigh index of suspicion is needed in the these groups to get an accurate diagnosisTreatmentAppendectomy is the standard of carePatients should be given IVF, and preoperative antibiotics Antibiotics are most effective when given preoperatively and they decrease post-op infections and abscess formationTreatmentThere are multiple acceptable antibiotics to use as long there is anaerobic flora, enterococci and gram(-) intestinal flora coverageOne sampl