Acute Appendicitis

Epidemiology

• 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.

Appendicitis:

• The most common surgical condition of the abdomen

• Lifetime occurrence of 7%

• Peak incidence 10-30y

• The most common nonobstetric surgical intervention during pregnancy

Pathogenesis:• Appendiceal lumen obstruction : lymphoid hyperplasia fecaliths parasites foreign bodies crohn’s disease metastatic cancer carcinoid syndrome

Pathophysiology

• Acute appendicitis is thought to begin with obstruction of the lumen

• Obstruction can result from food matter, adhesions, or lymphoid hyperplasia

• Mucosal secretions continue to increase intraluminal pressure

Pathophysiology

• Eventually the pressure exceeds capillary perfusion pressure and venous and lymphatic drainage are obstructed.

• With vascular compromise, epithelial mucosa breaks down and bacterial invasion by bowel flora occurs.

Pathophysiology

• Increased pressure also leads to arterial stasis and tissue infarction

• End result is perforation and spillage of infected appendiceal contents into the peritoneum

Pathophysiology

• Initial 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.

Pathophysiology

• As inflammation continues, the serosa and adjacent structures become inflamed

• This triggers somatic pain fibers, innervating the peritoneal structures.

• Typically causing pain in the RLQ

Pathophysiology

• The change in stimulation form visceral to somatic pain fibers explains the classic migration of pain in the periumbilical area to the RLQ seen with acute appendicitis.

Pathophysiology

• Exceptions exist in the classic presentation due to anatomic variability of the appendix

• Appendix can be retrocecal causing the pain to localize to the right flank

• In pregnancy, the appendix ca be shifted and patients can present with RUQ pain

Pathophysiology

• In 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 defecate

• Multiple anatomic variations explain the difficulty in diagnosing appendicitis

symptoms :

• Pain – RLQ / RUQ / Flank• Anorexia• Vomiting• Nausea • Pain migration• Fever

Physical examination:

• Tenderness – RLQ• Rebound & Guarding (peritoneal signs)• Rovsing sign• Dunphy’s sign• Psoas sign (retroperitoneal retrocecal appendix) • Obturator sign (pelvic appendix)• Rectal examination tenderness (cul-de-sac)• Low grade fever

                                                                                                     

Psoassign

Obturatorsign

History

• Primary symptom: abdominal pain• ½ to 2/3 of patients have the classical

presentation• Pain beginning in epigastrium or periumbilical

area that is vague and hard to localize

History

• Associated symptoms: indigestion, discomfort, flatus, need to defecate, anorexia, nausea, vomiting

• As the illness progresses RLQ localization typically occurs

• RLQ pain was 81 % sensitive and 53% specific for diagnosis

History

• Migration of pain from initial periumbilical to RLQ was 64% sensitive and 82% specific

• Anorexia is the most common of associated symptoms

• Vomiting is more variable, occuring in about ½ of patients

Physical Exam

• Findings depend on duration of illness prior to exam.

• Early on patients may not have localized tenderness

• With progression there is tenderness to deep palpation over McBurney’s point

Physical Exam

• McBurney’s Point: just below the middle of a line connecting the umbilicus and the ASIS

• Rovsing’s: pain in RLQ with palpation to LLQ• Rectal exam: pain can be most pronounced if

the patient has pelvic appendix

Physical Exam

• Additional components that may be helpful in diagnosis: rebound tenderness, voluntary guarding, muscular rigidity, tenderness on rectal

Physical Exam

• Psoas sign: place patient in L lateral decubitus and extend R leg at the hip. If there is pain with this movement, then the sign is positive.

• Obturator sign: passively flex the R hip and knee and internally rotate the hip. If there is increased pain then the sign is positive

Physical Exam

• Fever: another late finding.• At the onset of pain fever is usually not found.

• Temperatures >39 C are uncommon in first 24

h, but not uncommon after rupture

Lab:

• CBC – WBC ( 80% 45% )• CRP • Urinalysis - mild pyuria mild proteinuria mild hematuria

D.D.:surgical: gyneco:

• Renal stone • Gastroenteritis• Pancreatitis• Cholecystitis• Mesenteric adenitis• Hernia• Bowel obstruction

• Preterm labor• Placenta abruptio• Chorioamnionitis• Adnexal torsion • Ectopic pregnancy• Pelvic inflammatory• Round lig. pain

Diagnostic problems:

• Position of appendix: normally 70% intraperitoneal

30% pelvic, retroileal, retrocolic

pregnancy – anatomical changes

gravid uterus displacement upward &

outward flank pain (3rd trimester) (Baer,1932)

increased separation of peritoneum decreased perception of somatic pain and localization

Diagnostic problems:

• Symptoms complex – physical changes anorexia, nausea & vomiting in normal pregnancy• Lab – relative leukocytosis• Imaging techniques

Diagnosis

• Acute appendicitis should be suspected in anyone with epigastric, periumbilical, right flank, or right sided abd pain who has not had an appendectomy

Diagnosis

• Women of child bearing age need a pelvic exam and a pregnancy test.

• Additional studies: CBC, UA, imaging studies

Diagnosis

• CBC: the 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

results

Diagnosis

• UA: abnormal UA results are found in 19-40%• Abnormalities include: pyuria, hematuria,

bacteruria• Presence of >20 wbc per field should increase

consideration of Urinary tract pathology

Imaging:

• KUB• Barium enema• Graded compression ultrasonography• Helical CT scan

Diagnosis

• Imaging studies: include X-rays, US, CT• Xrays of abd are abnormal in 24-95%• Abnormal findings include: fecalith,

appendiceal gas, localized paralytic ileus, blurred right psoas, and free air

• Abdominal xrays have limited use b/c the findings are seen in multiple other processes

Graded compression ultrasound:• Normal appendix (<6mm) rules out

appendicitis. • Nonpregnant – Sensitivity 85% specificity 92%• Pregnant – cecal displacement & uterine

imposition makes precise examination difficult (Williams,21 edition)

Diagnosis

• Graded Compression US: reported sensitivity 94.7% and specificity 88.9%

• Basis of this technique is that normal bowel and appendix can be compressed whereas an inflamed appendix can not be compressed

• DX: noncompressible >6mm appendix, appendicolith, periappendiceal abscess

Diagnosis

• Limitations of US: retrocecal appendix may not be visualized, perforations may be missed due to return to normal diameter

Diagnosis

• CT: best choice based on availability and alternative diagnoses.

• In one study, CT had greater sensitivity, accuracy, -predictive value

• Even if appendix is not visualized, diagnose can be made with localized fat stranding in RLQ.

Diagnosis

• CT appears to change management decisions and decreases unnecessary appendectomies in women, but it is not as useful for changing management in men.

Special Populations

• Very young, very old, pregnant, and HIV patients present atypically and often have delayed diagnosis

• High index of suspicion is needed in the these groups to get an accurate diagnosis

Treatment

• Appendectomy is the standard of care• Patients should be NPO, given IVF, and

preoperative antibiotics • Antibiotics are most effective when given

preoperatively and they decrease post-op infections and abscess formation

Treatment

• There are multiple acceptable antibiotics to use as long there is anaerobic flora, enterococci and gram(-) intestinal flora coverage

• One sample monotherapy regimen is Zosyn 3.375g or Unasyn 3g

• Also, short acting narcotics should be used for pain management

Disposition

• Abdominal pain patients can be put in 4 groups

• Group 1: classic presentation for Acute appendicitis- prompt surgical intervention

• Group 2: suspicious, but not diagnosed appendicitis- benefit from imaging and 4-6h observation with surgical consult if serial exam changes or imaging studies confirm

Disposition

• Group 3: remote possibility of appendicitis- observe in ED for serial exams; if no change and course remains benign patient can D/C with dx of nonspecific abd pain

• Patients are given instructions to return if worsening of symptoms, and they should be seen by PCP in 12-24 h

• Also advised to avoid strong analgesia

Disposition

• Group 4: high risk population(including elderly, pediatric, pregnant and immunocomprimised)- require high index of suspicion and low threshold for imaging and surgical consultation

Prognosis:

• Generally good : Disease found Surgery complications

The end