Acute Appendicitis

Acute Appendicitis Dr Ibrahim Bashayreh

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.

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

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

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% • C-Reactive Protien CRP (independent surgical indication marker for appendicitis) 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

Diagnosis • Imaging studies: include X-rays, US, CT • Xrays of abd are abnormal in 24-95% • Abnormal findings include: fecalith, appendiceal gas, localized paralytic ileu, and free air • Abdominal xrays have limited use b/c the findings are seen in multiple other processes

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

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

Acute Appendicitis