Acute Appendicitis

Acute Appendicitis

Anatomy and Function first becomes visible in the eighth week of embryologic development as a protuberance off the terminal portion of the cecum. The three taeniae coli converge at the junction of the cecum with the appendix and can be a useful landmark to identify the appendix.

The appendix can vary in length from <1 cm to >30 cm; most appendices are 6 to 9 cm long.

It can be found in a retrocecal, pelvic, subcecal, preileal, or right pericolic position.

the appendix is an immunologic organ that actively participates in the secretion of immunoglobulins, particularly immunoglobulin A. Lymphoid tissue first appears in the appendix approximately 2 weeks after birth. Although there is no clear role for the appendix in the development of human disease, recent studies demonstrate a potential correlation between appendectomy and the development of inflammatory bowel disease. appendectomy is associated with a more benign phenotype in ulcerative colitis and a delay in onset of disease. The association between Crohn's disease and appendectomy is less clear.

Epidemiology Despite newer imaging techniques, acute appendicitis can be very difficult to diagnose. Peak incidence in adolescents and young adults, with a slight male predominance in this age group. Infants, elderly, pregnant women and immunocompromised patients tend to have atypical presentations and have higher morbidity and mortality.

Incidence The lifetime rate of appendectomy is 12% for men and 25% for women, with approximately 7% of all people undergoing appendectomy for acute appendicitis during their lifetime.

The percentage of misdiagnosed cases of appendicitis is significantly higher among women than among men (22.2 vs. 9.3%).

Etiology and 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

Etiology and Pathophysiology Faecolith Kinks Adhesions Worms Gallstone Hernia Endometriosis Barium Tumour Obstruction of the lumen is the dominant etiologic factor in acute appendicitis. Fecaliths are the most common cause of appendiceal obstruction.

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

Pathogenesis Luminal obstruction Bacterial stasis Distention Ischemia Focal necrosis Perforation

Bacteriology The principal organisms seen in the normal appendix, in acute appendicitis, and in perforated appendicitis are Escherichia coli and Bacteroides fragilis. Appendicitis is a polymicrobial infection, with some series reporting the culture of up to 14 different organisms in patients with perforation. Antibiotic coverage is limited to 24 to 48 hours in cases of nonperforated appendicitis. For perforated appendicitis, 7 to 10 days of therapy is recommended.

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 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 Associated symptoms: indigestion, discomfort, flatus, need to defecate, anorexia, nausea, vomiting As the illness progresses RLQ localization typically occurs 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 Additional components that may be helpful in diagnosis: rebound tenderness, voluntary guarding, muscular rigidity, tenderness on rectal

Physical Exam McBurney’s Point: just below the middle of a line connecting the umbilicus and the ASIS Rousing’s: pain in RLQ with palpation to LLQ Rectal exam: pain can be most pronounced if the patient has pelvic appendix

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 CBC: the WBC is of limited value. CRP and ESR have been studied with mixed results 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 ileus, blurred right psoas, 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 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. Note the thick-walled and dilated appendix mesenteric streaking and "dirty fat"

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

Differential Diagnosis Intra-abdominal conditions Acute Appendicitis Acute Cholecystitis Diverticulitis (Meckel’s) Inflammatory Bowel Disease (Crohn’s) Duodenal Ulcer Intestinal Obstruction Carcinoma of the Cecum Nonspecific adenitis – Possible Yersinia infection

Differential Diagnosis (cont.) Intra-pelvic conditions Salpingitis Pelvic Inflammatory Disease Ectopic Pregnancy Ruptured Corpus Luteum Cyst Ruptured Follicular Cyst (Mittelschmerz) Ruptured Ovarian Cyst Ovarian Torsion Pyelonephritis Ureteral/Renal stone

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 Also, short acting narcotics should be used for pain management

Tumors Primary appendiceal cancer is diagnosed in 0.9 to 1.4% of appendectomy specimens representing >50% of the primary lesions of the appendix mucinous adenocarcinoma (38% of total reported cases), adenocarcinoma (26%), carcinoid (17%), goblet cell carcinoma (15%), and signet-ring cell carcinoma (4%)

Carcinoid firm, yellow, bulbar mass in the appendix The appendix is the most common site of GI carcinoid, followed by the small bowel and then the rectum. Carcinoid syndrome is rarely. Unless widespread metastases are present, which occur in 2.9% of cases.