E-Case #3C

David True, MD

January 7-18, 2002

A 46yr old type 1 diabetic patient presents to a colleague with midline low abdominal pain of 3 days duration. He is afebrile and not experiencing nausea, vomiting, or change in bowel habits. He notes that he is experiencing anorexia. He denies dysuria or frequency. However, he is a hemodialysis patient with end-stage diabetic renal disease. He also suffers from schizophrenia, which has been only moderately controlled. A urinalysis is checked, which is negative, and a CBC is requested.

The patient returns the next day and has now been experiencing nausea and emesis X 2. He notes subjective fever and says; "I'm just not feeling very well". Pain is still in the low midline but worse now in the RLQ. Temp is 99.6. Exam of the abdomen demonstrates rebound pain on the L side with guarding in the RLQ. Chest and cardiac exam are unremarkable. The CBC from the previous day shows a leukocytosis with WBC count of 15K. A left shift is present with elevated PMN's at 13K.

What is your differential diagnosis?

What additional studies would you order?

The patient demonstrates evidence of an acute abdomen with rebound tenderness, fever, and leukocytosis. The differential is long but would include bowel obstruction, appendicitis, diverticulitis, duodenal ulcer, pancreatitis, cholelithiasis, renal colic secondary to nephrolithiasis, pyelonephritis, or perinephric abscess, or a metabolic cause such as DKA.

Additional studies could include serum amylase, LFT's, chem-7 panel, C-reactive protein and imaging studies such as abdominal series, ultrasound, or spiral CT with oral contrast.

A spiral CT with oral contrast was ordered which demonstrated appendiceal edema of greater than 6mm and the presence of an appendicolith. The patient was admitted to surgery with open appendectomy performed demonstrating an acute appendicitis.

Acute Appendicitis: Discussion

Appendicitis is the most common surgical condition of the abdomen. Peak incidence is between the ages 10-30 years with a lifetime occurrence of 7 percent. Despite newer technologies, diagnosis is still based primarily on the history and physical. Perforation with resultant peritonitis is the primary risk. Mortality for non-perforated cases is 1 percent  but can rise to 5 percent in young or elderly patients. Prompt diagnosis and surgical referral is essential.

Classically the symptom sequence proceeds within 24-36 hours from a vague periumbilical pain to anorexia, nausea and non-sustained vomiting. Pain then migrates to the RLQ and is accompanied by low-grade fever. Such a presentation is present in only 50% of cases. Abdominal pain and anorexia are present almost universally.

Exam findings can include RLQ tenderness, rebound tenderness, elevated temp (< 38^o), psoas/obturator sign, & tenderness on rectal exam. The location of the appendix can vary and can lead to varying exam findings. A retrocecal appendix can produce flank pain with a positive psoas sign. A pelvic appendix may result in rectal tenderness and a positive obturator sign.

Laboratory/ radiologic studies are helpful with leukocytosis present in 80% and neutrophilia present in 95% of cases. Unfortunately, these are non-specific findings in abdominal pain. Ultrasound demonstrates a sensitivity of 85% and specificity of 92%. It is helpful during pregnancy and is the best study for children. Spiral CT (combined with enema contrast) has a sensitivity of 90-100% and specificity of 95-97%.

Ultrasound or spiral CT studies are not essential for the diagnosis of appendicitis and are most helpful in equivocal or high-risk cases including the young, elderly, and immuno-compromised patients.

References:

Hardin, Mike D.; Acute Appendicitis: Review and Update; Am Fam Physician 1999; 60:2027-34

Nipper, M.L., & Jacobson, L.K.; Expanded applications of CT,  Postgrad Med 2001; 109(6):68-77