Non surgical mimics of appendicitis on imaging
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Non surgical mimics of appendicitis on imaging
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Non surgical mimics of appendicitis on imaging
- 2. OVERVIEW INRODUCTION NORMAL APPENDIX APPENDICITIS SCANNING TECHNIQUE GASTROINTESTINAL NONSURGICAL MIMICS OF APPENDICITIS Mesenteric adenitis Bacterial ileocecitis Crohns disease
- 3. Right-sided colonic diverticulitis Epiploic appendagitis Omental infarction OTHER NONSURGICAL MIMICS OF APPENDICITIS Gynecologic conditions Urolithiasis Rectus sheath hematoma CONCLUSION
- 4. INTRODUCTION Appendicitis is inflammation of the vermiform appendix. It is a very common condition in general radiology practice and is one of the main causes of abdominal surgery in young patients. Disease of children and young adults (2nd to 3rd decades of life)
- 5. There are certain nonsurgical appendicitis-mimicking diseases. A correct imaging diagnosis prevents an unnecessary operation or costly in-hospital observation.
- 6. NORMAL APPENDIX The appendix is a blind-ending tubular structure arising from the cecum. Sonography and CT allow direct visualization of the normal or inflamed appendix. The normal appendix can be identified in 67-100% of patients without appendicitis who undergo CT.
- 7. At sonography the normal appendix is less frequently visualized, with results varying between 0-82%. A normal appendix has a maximum outer diameter of 6 mm, is surrounded by homogeneous non-inflamed fat, and often contains intraluminal gas.
- 10. ACUTE APPENDICITIS Classical presentation consists of periumbilical pain (referred) which within a day or later localizes to McBurney's point (RIF) with associated fever, nausea and vomiting. Unhelpful in children who often present with vague and nonspecific signs and symptoms.
- 11. Appendicitis is typically caused by obstruction of the appendiceal lumen*. Obstruction may be caused by : Lymphoid hyperplasia (~60%) Appendicolith (~33%) Foreign bodies (~4%) Crohn disease or other rare causes, e.g. Stricture, tumor, parasite.
- 12. One of the biggest challenges of imaging the appendix is finding it. The location of the base of appendix is relatively constant, located roughly between the ileocecal valve and the apex of the caecum. The location of the tip of the appendix is much more variable, especially as the length of the appendix has an extensive range (2-20 cm) .
- 13. The distribution of positions are described as : Behind the caecum (ascending retrocaecal): 65% Inferior to the caecum (subcaecal): 31% Behind the caecum (transverse retrocaecal): 2% Anterior to the ileum (ascending paracaecal preileal): 1% Posterior to the ileum (ascending paracaecal retroileal): 0.5%
- 14. ULTRASOUND With a competent user, ultrasonography is reliable at identifying abnormal appendixes, especially in thin patients*. The technique used is known as graded compression, using the linear probe over the site of maximal tenderness, with gradual increasing pressure exerted to displace normal overlying bowel gas.
- 15. Findings supportive of the diagnosis of appendicitis include : Aperistaltic, non-compressible, dilated appendix ( >6 mm outer diameter) Appendicolith Distinct appendiceal wall layers Echogenic prominent pericaecal fat Periappendiceal fluid collection Target appearance (axial section)
- 18. SCANNING TECHNIQUE Graded compression ultrasonography : A linear array transducer, usually 5 or 7 MHz, is typically employed. The patient is initially examined in the supine position*. If no abnormality is found, then transverse and longitudinal images are obtained of the abdomen, including the right lower quadrant and the right lateral abdomen extending from the sub hepatic location to the right pelvis.
- 19. If an apparently normal appendix is identified, a careful survey of the entire length of the appendix should be performed. A positive exam consists of reproducible identification of an abnormal, inflamed appendix.
- 20. Atypical symptoms -- color Doppler sonography can be a useful adjunct to gray scale sonography for improving observer confidence in the diagnosis of appendicitis*. Another supportive sign for appendicitis is hyper vascularity of the appendix wall on color Doppler sonography**.
- 23. CT SCAN CT is highly sensitive (94-98%) and specific (up to 97%) for the diagnosis of acute appendicitis and allows for alternative causes of abdominal pain also to be diagnosed.
- 24. Findings include: Dilated appendix with distended lumen ( >6 mm diameter). Thickened and enhancing wall Thickening of the cecal apex (up to 80%): cecal bar sign, arrowhead sign Periappendiceal inflammation, including stranding of the adjacent fat and thickening of the lateroconal fascia or mesoappendix.
- 25. Extra luminal fluid Inflammatory phlegmon Abscess formation Appendicolith may also be identified
- 29. CECAL BAR SIGN ARROW HEAD SIGN
- 30. COMPLICATIONS Perforation: in up to 13-30% of cases Abscess formation: appendiceal abscess Generalized peritonitis Pylephlebitis: infective thrombophlebitis of the portal circulation Complicating hepatic abscess
- 32. MESENTERIC ADENITIS Second most common cause of right lower quadrant pain after appendicitis*. It is defined as a benign self-limiting inflammation of right-sided mesenteric lymph nodes without an identifiable underlying inflammatory process, occurring more often in children than in adults.
- 33. Features on CT/US modality include: 1. Enlarged lymph nodes 3 or more nodes with a short-axis diameter of at least 5 mm clustered in the right lower quadrant. 2. Ileal or ileocecal wall thickening may be present Wall is thicker than 3 mm over at least 5 cm of the bowel despite bowel lumen opacification (CT) and distention
- 37. BACTERIAL ILEOCECITIS Infectious enterocolitis may cause mild symptoms resembling a common viral gastroenteritis, but it may also clinically present with features indistinguishable from appendicitis. This latter presentation may occur in bacterial ileocecitis, caused by Yersinia, Campylobacter, or Salmonella*.
- 38. ULTRASOUND Mural thickening of the terminal ileum and cecum without inflammation of the surrounding fat and moderate mesenteric adenopathy.
- 39. CT SCAN Circumferential mural thickening of the terminal ileum and cecum with homogeneous enhancement and adjacent adenopathy. Stranding of the pericolic and mesenteric fat, a small amount of ascites, and air-fluid levels may or may not be associated.
- 42. CROHNS DISEASE Crohn disease is an idiopathic inflammatory bowel disease (IBD) characterized by widespread gastrointestinal tract involvement typically with skip lesions*. Peak onset is at 15–30 years of age.
- 43. The characteristic of Crohn disease is the presence of skip lesions and presence of discrete ulcers. The frequency with which various parts of the gastrointestinal tract are affected varies widely: Small bowel: 70-80% Small and large bowel: 50% Large bowel only: 15-20%
- 44. RADIOGRAPHIC FEATURES In the acute active phase of ileocecal Crohn disease, imaging shows transmural bowel wall thickening, often predominantly of the submucosal layer, with frequent inflammatory changes of the surrounding fat.
- 45. The two most common CT findings of Crohn disease are eccentric wall thickening and mucosal hyper enhancement; the latter is an indicator of inflammatory activity. Mural stratification due to intramural edema is also suggestive of active disease. Engorgement of the vasa recta that penetrate the bowel wall (the comb sign) is an extra enteric finding that correlates with clinically advanced, active, and extensive Crohn disease.
- 46. The presence of intramural fat usually indicates chronic changes. Fibro fatty proliferation along the mesenteric border of the affected bowel (the creeping fat sign) is another extra enteric finding; it is considered almost pathognomonic for Crohn disease.
- 50. RIGHT SIDED COLONIC DIVERTICULITIS Diverticulitis of the colon is one of the most common causes of acute abdominal pain in elderly patients*. **The right colon and cecum may be involved, clinically mimicking appendicitis.
- 51. Sonography and CT findings consist of inflammatory changes in the pericolic fat with segmental thickening of the colonic wall, at the level of an inflamed diverticulum.
- 55. EPIPLOIC APPENDAGITIS Epiploic appendages are round, fat-containing peritoneal pouches arising from the serosal surface of the colon that measure 0.5–5 cm in length. Epiploic appendagitis is an uncommon and self-limited condition, most often affecting middle-aged men*. **May involve the right colon and cecum, clinically mimicking appendicitis.
- 57. RADIOGRAPHIC FEATURES On sonography appears as rounded, non-compressible, hyper echoic mass, without internal vascularity, and surrounded by a subtle hypoechoic line. They are typically 2-4 cm in maximal diameter.
- 58. CT appearances are usually characteristic consisting of: A fat-density ovoid structure adjacent to colon, usually 1.5- 3.5cm in diameter. Thin high-density rim (1-3mm thick). Surrounding inflammatory fat stranding, and thickening of the adjacent peritoneum. Central hyper dense dot (representing the thrombosed vascular pedicle).
- 62. OMENTAL INFARCTION Omental infarction is a rare cause of acute abdomen resulting from vascular compromise of the greater omentum. Non-specific clinical presentation and is usually managed conservatively. Primary/Secondary*
- 63. RADIOGRAPHIC FEATURES Primary Omental infarction is usually seen in the right lower quadrant. Secondary Omental infarction is located at the site of initial insult. It is usually larger than 5 cm, which helps distinguishing it from Epiploic appendagitis. Ultrasound : focal area of increased echogenicity in the Omental fat.
- 64. CT appearance: Solitary, well-circumscribed, triangular or oval, heterogeneous fatty mass, sometimes with a whorled pattern of concentric linear fat stranding*. Swirling of omental vessels in omental torsion. Hyper dense peripheral halo.
- 68. OTHERS NONSURGICAL MIMICS OF APPENDICITIS
- 69. GYNAECOLOGICAL CONDITIONS Gynecologic conditions such as pelvic inflammatory disease or a hemorrhagic functional ovarian cyst can cause acute pelvic pain that may simulate appendicitis.
- 70. PELVIC INFLAMMATORY DISEASE Broad term that encompasses a spectrum of infection and inflammation of the upper female genital tract. Sexually active women Usually bilateral, except when it is caused by the direct extension of an adjacent inflammatory process.
- 71. RADIOGRAPHIC FEATURES Imaging features are often nonspecific. If imaged early (e.g. during the cervicitis stage), there may be no finding. If imaged very late, there may be an adnexal mass-like region with surrounding inflammatory change.
- 72. ULTRASOUND Ultrasound often only demonstrates ascitic fluid in the peritoneal cavity or nonspecific thickening and increased vascularity of the endometrium. In the most severe cases, ultrasound may show adnexal masses with a heterogeneous echo-pattern.
- 73. Some sonographic signs associated with tubal inflammation include: thickened/dilated fallopian tubes incomplete septa in the tube increased vascularity around the tube echogenic fluid in the tube (pyosalpinx) cogwheel sign
- 74. CT SCAN CT shows a diffusely-enhancing ill-defined pelvic mass, which may be difficult to differentiate from malignancy.
- 79. HEMORRHAGIC OVARIAN CYST Hemorrhagic ovarian cysts (HOCs) usually result from hemorrhage into a corpus luteum or other functional cyst. They typically resolve within eight weeks.
- 80. Sudden-onset pelvic pain, pelvic mass, or they may be asymptomatic and the HOC is an incidental finding.
- 81. ULTRASOUND lace-like reticular echoes or an intra cystic solid clot a fluid-fluid level is possible. thin wall clot may adhere to the cyst wall mimicking a nodule, but has no blood flow on Doppler imaging retracting clot may have sharp or concave borders, mural nodularity does not.
- 82. posterior acoustic enhancement there should not be any internal blood flow* If there is rupture of a hemorrhagic cyst, other findings may be present.
- 83. CT SCAN High- attenuation adnexal mass at unenhanced CT, and does not require any treatment.
- 87. UROLITHIASIS Urolithiasis may present with right lower quadrant pain when obstruction is caused by a distal ureteral stone. Unenhanced CT is more accurate in detecting ureteral stones than sonography. Ultrasound may show both hydronephrosis and hydroureter as signs of obstruction.
- 90. RECTUS SHEATH HEMATOMA *A small non-palpable hematomas may clinically mimic appendicitis and also occur in patients without anticoagulant. Sonography and CT show a hemorrhagic mass within the sheath of the rectus abdominis muscle. No treatment is required other than adjusting any anticoagulant therapy.
- 92. CONCLUSION A broad spectrum of nonsurgical diseases may clinically present as appendicitis in patients without appendicitis. The radiologist should be aware of the sonographic and CT features of these alternative disorders, as a correct imaging diagnosis prevents an unwarranted operation and unnecessary hospital resource use.
Editor's Notes
- healthy volunteer with a normal appendix. A and B, longitudinal (A) and transverse (B) sonogram, showing the appendix (arrowheads) with a diameter less than the 7 mm cut-off point, surrounded by normal noninflamed fat.
- CT shows an air-containing non-distended appendix (arrowheads), with homogeneous low-density periappendiceal fat.
- *with resultant build up of fluid, secondary infection, venous congestion, ischemia and necrosis
- *However, the identification of a normal appendix is more problematic, and in many instances, appendicitis cannot be ruled out.
- Longitudinal and transverse sonogram show an enlarged appendix (arrows) surrounded by hyperechoic inflamed fat (arrowheads)
- Ultrasound showing a thickened appendix measuring 1.1 cm with an echogenic shadowing appendicolith. Color Doppler evidences hyperemia of the mesoappendix.
- *Scanning should be initiated in the region of maximal pain indicated by the patient.
- to avoid a false negative examination when inflammation is confined to the tip of the appendix . addition of color Doppler ultrasound results in a sensitivity of 87%, specificity of 97%, and accuracy of 93% in the diagnosis of acute appendicitis in children. This likely reflects increasing hyperperfusion of the appendiceal wall accompanying worsening inflammation as well as peritoneal inflammation which may occur surrounding an inflammatory mass resulting from perforated appendicitis.
- *to avoid a false negative examination when inflammation is confined to the tip of the appendix . addition of color Doppler ultrasound results in a sensitivity of 87%, specificity of 97%, and accuracy of 93% in the diagnosis of acute appendicitis in children. **This likely reflects increasing hyperperfusion of the appendiceal wall accompanying worsening inflammation as well as peritoneal inflammation which may occur surrounding an inflammatory mass resulting from perforated appendicitis.
- Power Doppler sonography shows hypervascularity of the appendiceal wall.
- Normal proximal appendix is seen. Narrow transition from normal to abnormally dilated appendix is noted. No fecolith is seen at this point. Distal half of appendix is dilated. Fluid debris level is noted. Tip of appendix is directed to pelvis. Acute appendicitis with dilated and oedematous appendiceal wall.
- Distended appendix showing mural thickening and enhancement with blurring and smudging of the periappendiceal fat planes.
- Contrast-enhanced CT depicts a fluid-filled distended appendix (arrow) with enhancing walls and periappendiceal fat-stranding. At CT the inflamed appendix is surrounded by fat-stranding (Fig. 4).
- Atypical presentation of appendicitis in a young woman; computed tomography scan. The patient presented with an elevated white blood cell count and right upper quadrant pain. Left, there is pericholecystic fluid which is caused by retrocaecal appendicitis. Right, the appendix, observed in axial section, has an increased diameter and an enhancing thickened wall and surrounding fat stranding.
- It refers to the appearance of inflammatory soft tissue at the base of the appendix, separating the appendix from the contrast-filled caecum. The arrowhead sign refers to the focal caecal thickening centered on the appendiceal orifice, seen as a secondary sign in acute appendicitis. The contrast material in the cecal lumen assumes an arrowhead configuration, pointing at the appendix.
- *Accounting for 2-14% of the discharge diagnoses in patients with a clinical suspicion of appendicitis.
- Sonogram of the right lower quadrant shows a cluster of enlarged mesenteric lymph nodes (arrowheads). The appendix was normal (not shown) and no other abnormalities were found.
- Normal appendix (green arrow) and enlarged mesenteric lymphnodes (yellow arrows).
- CECT axial section slightly lower in the pelvis demonstrates several mildly enlarged right lower quadrant mesenteric lymph nodes (white arrows). The appendix (not shown) was normal in appearance.
- most cases do not require imaging owing to the self-limited nature of the symptoms,
- 39-year-old man with bacterial ileocecitis. A and B, Sonography shows moderate mural thickening of the terminal ileum and cecum, surrounded by normal noninflamed fat
- Infectious ileitis in a 32-year-old man with RLQP, fever, and bloody diarrhea. Culture of the stool demonstrated Y enterocolitica infection. Coronal CECT image shows a markedly thickened terminal ileum with mural stratification (arrow) and surrounding homogeneous non inflamed fat.
- Most patients experience chronic symptoms; however, acute exacerbations or complications may lead to acute abdominal pain. In fact, many cases of Crohn disease are diagnosed during work-up of acute RLQP, since the ileocecal region is most commonly affected by the disease
- diagnostic value of CT is based on excellent characterization of disease extension and severity, as well as estimation of inflammatory activity
- Small bowel strictures causing obstruction, fistulas, and abscesses are among the most common enteric complications associated with Crohn disease and are readily diagnosed with CT
- 28-year-old man with acute ileocecal Crohn disease.A and B, Sonography shows transmural wall thickening of the terminal ileum (arrows) in longitudinal (A) and transverse (B) section, with hyperechoic inflammatory changes of the surrounding fat (arrowheads).C, Contrast-enhanced CT confirms the wall thickening and luminal narrowing of the terminal and pre-terminal ileum (arrowheads), with regional fat-stranding.
- Coronal oblique CT image shows a thickened terminal ileum with strictures and mucosal hyperenhancement (white arrow). There is also proliferation of the mesenteric fat (black arrow).
- (b) Crohn disease in a 25-year-old woman with RLQP, fever, and leukocytosis. Axial oblique CT image shows a Y-shaped fistula (black arrow) between the distal ileum (white arrow) and cecum (arrowhead). The fistula is connected to an abscess in the right psoas muscle
- *Diverticulitis is the result of obstruction of the neck of the diverticulum, with subsequent inflammation, perforation and infection **typically manifests as left-sided lower abdominal pain, as the left and sigmoid colon are predominantly affected
- When the cecum or right colon is affected, demonstration of inflamed diverticula, usually located at the level of maximum pericolic inflammation, along with a normal appendix are key elements in differentiation from appendicitis
- 51-year-old man with right-sided colonic diverticulitis. A, Unenhanced CT shows extensive fat-standing along the cecal wall (arrowheads), and a normal appendix (arrow). B, Sonography reveals the cause of the inflammation by depicting an inflamed cecal diverticulum (arrow) centred in the hyperechoic fat
- In the lower left quadrant of the abdomen, on the point of referred pain, there is a thick-walled colon, here are some diverticula containing coprolites, the largest measuring 1.0 cm and associated with a significant increased echogenicity of adjacent fat. There are no adjacent collections.
- Right colonic diverticulitis in a 78-year-old man with a 3-day history of RLQP and anorexia. Coronal CT image shows multiple right colonic diverticula and adjacent fat stranding (arrow). Diverticula are also present in the sigmoid colon (arrowheads), but no inflammation is seen in the surrounding fat.
- *caused by inflammatory and ischemic changes related to torsion or venous thrombosis of the epiploic appendages. **epiploic appendages are larger and more numerous in the sigmoid and descending colon, appendagitis typically manifests as left lower quadrant pain, Epiploic appendages may also be present in the vermiform appendix and are usually smaller than those on the serosal surface of the colon It is very important to make a positive diagnosis of this characteristic entity since epiploic appendagitis is a self-limiting disease
- In region of maximal tenderness ( left iliac fossa ), there is ovoid, noncompressible, hyperechoic mass, without significant internal vascularity and thin hypoechoic line. Local mass effect is noted without bowel wall thickening or ascities.
- An oval fat attenuation lesion is seen adjacent to descending colon, with peripheral hyperdense rim, and streakiness in its periphery.
- 29-year-old woman with epiploic appendagitis. A, Sonography of the right lower quadrant reveals a hyperechoic inflamed fatty mass (arrowheads) adjacent to the colon (arrow), at the spot of maximum tenderness. B, On unenhanced CT the fatty lesion contains a characteristic hyperattenuating ring (arrow) corresponding to thickened visceral peritoneal lining.
- *primary omental infarction is in the right lower quadrant medial to the ascending colon or cecum. The vascular compromise occurs along the right edge of the greater omentum where the arterial supply is usually tenuous. Sometimes it is the result from kinking of venous channels in the inferior part of the greater omentum in the pelvis. Occasionally omentum twists on itself resulting in omental torsion leading to both arterial and venous compromise. The omentum may infarct without torsion, and this is called as primary idiopathic segmental infarction 2* post surgery, abdominal trauma, omental inflammation
- *It is mainly located between the anterior abdominal wall and the transverse or ascending colon, corresponding in location to the greater omentum
- 41-year-old man with omental infarction. A, Sonography of the right middle abdomen shows a large area of inflamed intraperitoneal fat (arrowheads). B, Unenhanced CT depicts the lesion as a cake-like area of dense inflamed omental fat (arrowheads), larger than in epiploic appendagitis and lacking a hyperattenuating ring.
- In region of maximal tenderness ( right lumbar / iliac fossa region ), there is an ovoid, noncompressible, hyperechoic mass, without significant internal vascularity. Internal hypoechoic rim like area is noted. Lesion abutts anterior abdominal wall near junction of rectus abdominis and oblique muscle. It is seperate from small / large bowel loops. APPENDIX could not be localized. Caecum and Terminal ilium are normal.
- Acute omental infarction in a 40-year-old man with acute onset of RLQP after exercising. Axial (a) and coronal (b) CT images show a triangular heterogeneous fatty mass (arrowheads) anterior to the ascending colon
- Endovaginal ultrasound scan. This image shows a relatively enlarged right ovary in a patient who had pain, increased flow, and a small amount of adjacent free fluid. These findings are compatible with oophoritis.
- Endovaginal sonogram. This image shows anechoic tubular structures in the adnexal area; the finding is compatible with a hydrosalpinx.
- 39-year-old woman with pelvic inflammatory disease.A, Endovaginal sonography shows an inhomogeneously enlarged right ovary (arrowheads).B and C, Contrast-enhanced CT shows enlargement of the ovaries (B, arrows) with ill-defined contours of the ovaries and uterus, and some free pelvic fluid (C, arrow).
- Fluid in the endometrial cavity with pelvic fat stranding suggestive of endometritis.
- *circumferential blood flow in the cyst wall is typical
- Lacelike internal echos are noted in this hemorrhage ovarian cyst
- Hemorrhagic cyst with a clot mimicking a neoplasm. Notice absence of flow and good through-transmission
- 40-year-old woman with a ureteral stone.A and B, Sonography shows right-sided hydronephrosis (A), and an obstructing calculus (B, arrow) in the distal ureter at the level of the iliac vessels
- 77-year-old man with a right ureteral stone.Unenhanced CT shows an obstructing calcification (arrow) within the distal ureteral lumen.
- *A rectus sheath hematoma may be easy to diagnose in patients presenting with a painful palpable mass under anticoagulant therapy, however,
- 68-year-old woman with a rectus sheath hematoma.A, Sonography depicts a small painfull lesion (arrow) within the sheath of the rectus abdominis muscle in the right lower quadrant. The lesion contains a fluid-fluid level.B, Unenhanced CT depicts the lesion as a partly hyperdense mass (arrow) within the rectus sheath.