• Information
  1. Overview
  2. Symptoms
  3. Pathophysiology
  4. Diagnosis
  5. Differential Diagnosis
  6. Treatment

A. Overview

1. Common cause of abdominal pain
2. About 250,000 new cases per year in USA, with ~6% lifetime risk
3. Highly variable presentation
4. Requires high degree of suspicion in any patient with abdominal or flank pain
5. Seriel observation of patient is critical
6. Diagnosis of acute appendicitis is incorrect in ~20% of surgically removed organs
   1. Diagnosis is missed in a number of cases (due mainly to variable presentation)
   2. Inappropriate surgical procedures are carried out due to incorrect diagnosis
   3. Neuroimmune appendicitis with pain but little inflammation may be responsible [2]

B. Symptoms [3]

1. Fever
   1. Fever with abdominal pain in children increases likelihood of appendicitis 3.4
   2. Absence of abdominal pain reduces likelihood of appendicitis by 70%
2. Nausea and vomiting
3. Nonspecific colicky abdominal pain, possibly with inital diarrhea
4. Typical Pain Patterns [3]
   1. Only present in ~20% of patients
   2. Pain usually begins in mid epigastrium or periumbilical area
   3. It then migrates to right (R) lower quadrant (RLQ)
   4. Focal tenderness is present in RLQ in most patient
   5. Location of focal pain is completely dependent on position of appendix
   6. Pain migrating from midepigastrium to RLQ more likely appendicitis than pure RLQ pain
   7. Rebound tenderness triples odds of appendicitis
5. Atypical Pain Patterns
   1. RUQ or R flank tenderness - elevated cecum (riding high in abdominal cavity)
   2. Deep RLQ pain - appendix lying deep in RLQ
   3. Bladder symptoms may occur due to irritation of bladder
   4. Women may have pain associated with inflammation of ovary and/or fallopian tube
   5. May mimic pelvic inflammatory disease
6. Delay in presentation >12 hours after symptom onset associated with perforations

C. Pathophysiology

1. Generally caused by obstruction of appendix by appendicolith (stone)
2. Obstruction leads to pressure build up, bacterial invasion, increased inflammation
3. Perforation follows if treatment not instituted
4. Peritonitis, sepsis and death may result without treatment
5. Neuroimmune Appendicitis [2]
   1. Pain without acute inflammation may occur
   2. Increased substance P or vasoactive intestinal peptide (VIP) activity present
   3. This disorder may account for non-inflammatory appendicitis found in ~20% of cases

D. Diagnosis

1. High clinical suspicion is critical to avoid missing cases of appendicitis
   1. Clinical history is key in considering diagnosis
   2. Careful physical examination is necessary
   3. Despite careful history and physical, diagnosis may be very difficult [4]
2. Variant clinical presentations are not uncommon (~20%)
   1. Right upper quadrant pain
   2. Pain may begin in epigrasrium or hypogastrium
   3. Pain may be in flank region, particularly with retroperitoneal appendix
3. Laboratory
   1. Leukocytosis with left shift (immature forms)
   2. Total white cell count <10K/µL reduces likelihood of appendicitis to 0.22
   3. An absolute neutrophil count of <6750/µL associated with likelihood ratio of 0.06
   4. Hyponatremia
   5. Acidosis - usually due to bicarbonate loss in intestine
4. Radiographic
   1. Plain X-rays are non-specific, often showing air-fluid levels typical of ileus
   2. Calcified stone may be visible in appendix area
   3. Ultrasound is initial study but computed tomography (CT) is more accurate [5]
   4. CT sensitivity 0.94, speificity 0.95; Ultrasound sensitivity 0.86, specificity 0.81
   5. CT is extremely helpful and cost effective in confiming diagnosis [6]
   6. If ultrasound is indeterminant or negative but clinical suspicion is high, then patients should definitely undergo CT scan with rectal contrast [7]
   7. CT may replace ultrasound as initial diagnostic test
5. Surgical exploration and verification is gold standard

E. Differential Diagnosis

1. Crohn's Disease
2. Psoas Abscess
3. Pyelonephritis
4. Pelvic abscess, ovarian disease, fallopian tube disease
5. Pelvic inflammatory disease
6. Cholecystitis
7. Intestinal perforation due to obstruction (e.g. right sided colon cancer)
8. Non-inflammmatory neuroimmune appendicitis [2]

F. Treatment

1. Surgery
   1. Removal of appendix is definitive therapy
   2. Laparoscopic surgery has reduced wound infection risk, earlier return to acitivites
2. Fluid management is critical
3. Antibiotic therapy, including anaerobic coverage, is required

References

1. Pauker SG and Kopelman RI. 1994. NEJM. 330(22):1596 (Case Discussion)
2. Di Sebastiono P, Fink T, Di Mola FF, et al. 1999. Lancet. 354(9177):461
3. Bundy DG, Byerley JS, Liles EA, et al. 2007. JAMA. 298(4):438
4. Fisk DT, Saint S, Tierney LM Jr. 1999. NEJM. 341(10):747 (Case Discussion)
5. Terasawa T, Blcakmore CC, Bent S, Kohlwes RJ. 2004. Ann Intern Med. 141(7):537
6. Rao PM, Rhea JT, Novelline RA, et al. 1998. NEJM. 338(3):141
7. Garcia Pena BM, Mandl KD, Kraus SJ, et al. 1999. JAMA. 282(11):1041