1. MedPix Medical Image Database COW - Case of the Week Case Contributor: Jason Capra Affiliation: Uniformed Services University

2. MedPix No: 9367 - History Pt Demographics: Age = 18 y.o. Gender = man 18yo man presents to the ER c/o 5d of RLQ abdominal pain and nausea. The patient states that his siblings have had flu-like illnesses recently with nausea and vomiting, so he initially attributed his symptoms to a virus. However, over the last 5 days the pain has progressively worsened. Pain is described as intermittent, stabbing, improved with Tylenol, and aggravated by movement. The patient has never had pain like this before. ROS: significant for RLQ abdominal pain, nausea, 1 episode of non bloody, non bilious vomiting 2 days prior to admission, and subjective chills. Denies fevers, diarrhea, hematochezia, or dysuria. Downloaded by (-1)

3. MedPix No: 9367 - EXAM & LABS Vitals: Temp: 103.1, BP 132/71, HR 88, RR 30, O2 sat 995 on RAGeneral: Thin appearing male laying still on exam table, in tears due to painHeart: No murmursLungs: Clear to auscultation BL, no wheezes or rhonchiAbdomen: No discoloration, no distension. + bowel sounds. Tender to percussion and palpation over McBurneys point. No rebound tenderness. + Rovsings sign.Genitalia: Normal ext male genitalia, testes descendedRectal: Normal tone, no masses, tender with pressure aimed towards RLQ, no masses.CBC: 12.1 > 15.5/45.6 < 166CMP: 139/4.4/102/30/17/1.0/100Ca: 9.2 AST: 13 ALT: 29 AP: 84UA: Yellow, clear, SG 1.026, Ph 6.0, neg prot, ket, gluc, bili, nitrite, LE. 1-3 WBC, Mod Blood, 4-10 RBC, squam 1-2/HPF

4. Ruptured Appendicitis No evidence of free air. Evidence of free fluid within the pelvis with indistinctness of the fat planes. Two calcifications are seen within the right pelvis, one measuring approximately 12mm and one measuring approximately 5 mm in size. Bowel gas pattern unremarkable, no air fluid levels Downloaded by (-1)

5. Ruptured Appendicitis The appendix is markedly enlarged and edematous. There is a - large inflammatory mass surrounding the appendix. There is enhancement of - the wall of the appendix. An appendicolith is visible within the appendix, the appendix is - dilated, but there is no evidence of free air. - Downloaded by (-1)

6. Ruptured Appendicitis The appendix is markedly enlarged, edematous and/or obstructed (arrowheads). The appendicolith is clearly shown (arrow). - Downloaded by (-1)

7. Ruptured Appendicitis A second smaller appendicolith is present. There is a large inflammatory mass surrounding the appendix. There is enhancement of the wall of the appendix. Downloaded by (-1)

8. Ruptured Appendicitis There is a moderate amount of free fluid within the pelvis. There is no evidence of free air. Downloaded by (-1)

9. FINDINGS Supine and upright abdominal radiographs: No evidence of free air. Evidence of free fluid within the pelvis with indistinctness of the fat planes. Two calcifications are seen within the right pelvis, one measuring approximately 12mm and one measuring approximately 5 mm in size. Bowel gas pattern unremarkable, no air fluid levelsAbdominal CT: The appendix is markedly enlarged and edematous. There is alarge inflammatory mass surrounding the appendix. There is enhancement ofthe wall of the appendix. There are two appendicoliths within the appendix,one measuring 12 mm in greatest diameter and a smaller 6 mm appendicolith. There is a moderate amount of free fluid within the pelvis. The appendix isdilated to a maximum diameter of 12.5 mm. There is no evidence of free air.

10. DIFFERENTIAL DIAGNOSIS What is your Differential Diagnosis? Ruptured Appendicitis - Mesenteric Adenitis - Psoas abscess - Ureteral Calculus -

11. Diagnosis: Ruptured Appendicitis Dx Confirmed by: CT of abdomen and open surgical removal of ruptured appendix with subsequent pathologic tissue examination.

12. DISCUSSION Since the first description of acute appendicitis in 1886 by Reginald Fitz, it has been recognized as one of the most common causes of the acute abdomen worldwide; with 250,000 cases yearly in the United States. Sixty five percent of patients that have symptoms of acute appendicitis for longer than 48 hours present with perforation of the appendix due to significant inflammation and necrosis. Perforation of the appendix can cause widespread intraperitoneal contamination or a sealed-off abscess, and can be lethal if not promptly recognized. The size of the perforation, the virulence of bacterial infection, and the ability of the infection to be contained will determine the extent of the inflammatory response. Abscesses are variable in size, have low attenuation numbers (10 to 30 Hounsfield units) and may display an identifiable capsule which signals chronicity. If the abscess is due to gas- forming bacteria or fistulization to bowel occurs, bubbles of air or air-fluid levels may be observed. Abscesses may be found in locations distant from the cecum due to variable position of the appendix and the patterns of fluid migration in the peritoneal cavity. Most abscesses are located inferior, medial, or posterior to the cecum or in the right paracolic gutter. - - It has been suggested that imaging is not necessary if a patient presents with history and physical exam strongly suggestive of acute appendicitis. However, imaging is advisable for the patients with atypical symptoms, infants, small children, and young women - - Radiographs demonstrate some abnormality in up to 80% of patients with acute appendicitis. Appendicoliths are the most specific radiographic sign, but are only found in 10% of patients with acute appendicitis. However, when an appendicolith is present, the incidence of perforation is nearly 50%. Appendicoliths can be differentiated from bone islands, ureteral stones and pheleboliths by their calcified rims. In cases of retrocecal appendicitis, the appendicolith may be located in the right upper quadrant. Other radiographic findings suggestive of acute appendicitis are: cecal ileus, right lower quadrant fluid levels, paucity of right lower quadrant gas, distortion of flank stripe, loss of psoas margin, loss of properitoneal flank stripe, thickening of cecal wall, scoliosis, mottled gas collection in right lower quadrant, and pneumoperitoneum - - High resolution or helical CT techniques have been shown to be superior to radiographs in establishing the diagnosis of acute appendicitis due to high accuracy and sensitivity. CT scans have accuracy of 96% to 98%, sensitivity of 96% to 100%, specificity 95% to 97%, a PPV of 97% to 99%, and a NPV of 88% to 100% - The diagnosis of appendicitis can be made with confidence when an abnormal appendix is identified or when an appendicolith associated with a phlegmon or abscess is detected in the right lower quadrant. The abnormal appendix appears slightly distended, fluid filled structure about 0.5 to 2cm in diameter. In almost all cases of acute appendicitis, the appendiceal wall may display circumferential and asymmetrical thickening. Periappendicieal inflammation is another hallmark of acute appendicitis. The inflammatory response is variable and may show the following: Slightly increased hazy density of the mesenteric fat, linear strands, fluid containing abscesses, or heterogeneous ill defined soft tissue densities representing a phelgmon. A summary of findings of acute appendicitis seen on CT scan are listed below: - - Circumferential mural thickening of appendix - Mural contrast enhancement - Appendicolith - Hazy, streaked periappendiceal densities - Pericecal soft tissue mass (phlegmon) - Pericecal fluid collection (abscess) - Mural thickening of adjacent cecum and terminal ileum Arrowhead sign - Cecal bar - Focal cecal apical thickening - Enlarged lymph nodes - Pneumoperitoneum - - In patients without acute appendicitis CT is also useful as it is able to diagnose other intra abdominal conditions. Using CT in patients with equivocal clinical presentations leads to a substantial decrease in the expected negative appendectomy rate. (4% compared to an expected 20% negative laparotomy rate based on clinical evaluation.) -