Appendicolith (fecalith) is calcified or partially calcified fecal material formed within the appendiceal lumen. It develops from progressive mineralization of fecal residue with calcium salts around an organic core. Appendicoliths may be asymptomatic or trigger acute appendicitis by obstructing the appendiceal lumen. Appendicoliths are found in 10-30% of acute appendicitis cases and increase the risk of complicated (gangrenous/perforated) appendicitis. On imaging, they are easily recognized as intraluminal calcified structures.
Age Range
10-60
Peak Age
25
Gender
Equal
Prevalence
Common
Appendicolith formation is a multi-stage process. In the first stage, undigested food residue, fecal material, or plant fibers accumulate in the appendiceal lumen and form an organic core. Calcium carbonate and calcium phosphate salts from intestinal fluid precipitate in concentric lamellae around this core — this mineralization process can take months or years. As the appendicolith grows, it partially or completely obstructs the appendiceal lumen; obstruction leads to increased intraluminal pressure, mucosal ischemia, and bacterial proliferation, triggering acute appendicitis. The high atomic number (Ca: Z=20) and electron density of calcium salts produce high attenuation (100-1000+ HU) on CT — therefore appendicoliths are easily detected on CT. On ultrasonography, the high acoustic impedance difference produces strong reflection with posterior acoustic shadowing — this ultrasound finding has pathognomonic value. When appendicitis develops with an appendicolith present, the risk of complication (gangrene, perforation) increases 2-3 fold compared to cases without appendicolith.
Highly echogenic, fixed intraluminal structure in the appendiceal lumen with clean posterior acoustic shadowing behind it. This finding is considered pathognomonic for calcified appendicolith and reliably distinguishes from bowel gas (dirty shadowing, position change).
Round or oval, high-density (100-1000+ HU) calcified structure in the appendiceal lumen. Size can range from 2 mm to 20 mm. Concentric lamellar structure may be seen in large appendicoliths. Can be single or multiple.
Report Sentence
A high-density (__ HU) calcified structure (appendicolith) measuring __ mm in the appendiceal lumen is observed.
Acute appendicitis findings with appendicolith: increased appendiceal diameter (>6 mm), wall thickening and enhancement, periappendiceal fat stranding. Complicated appendicitis risk is high in the presence of appendicolith — loss of wall enhancement (gangrene) or periappendiceal free fluid/air (perforation) should be investigated.
Report Sentence
Acute appendicitis findings are observed together with appendicolith in the appendiceal lumen; careful evaluation for complicated appendicitis is recommended.
Highly echogenic focus with clean posterior acoustic shadowing in the appendiceal lumen. Appendicolith does not change position (fixed intraluminal structure). Echogenicity of appendicolith should be distinguished from bowel gas — appendicolith shows solid, fixed appearance with clean shadowing, while gas shows dirty shadowing and position change.
Report Sentence
An echogenic structure with posterior acoustic shadowing is observed in the appendiceal lumen, compatible with appendicolith.
Concentric lamellar (ring-shaped) calcification pattern may be seen in large appendicoliths. This pattern reflects mineral deposition occurring in layers over time. The central organic core may show lower density.
Report Sentence
Concentric lamellar calcification pattern is observed in the appendicolith.
If acute appendicitis has developed with appendicolith, increased vascularity is observed in the periappendiceal region on Doppler ultrasonography. Appendicolith is recognized by echogenic focus and shadowing; surrounding tissue hypervascularity confirms the inflammatory process.
Report Sentence
Increased periappendiceal vascularity around the appendicolith is observed on Doppler, supporting an acute inflammatory process.
Criteria
Entire structure shows homogeneous high density (>200 HU). Organic core is completely mineralized.
Distinct Features
Prominent calcification on CT and US. Detectable on plain radiograph. Obstruction risk proportional to size.
Criteria
Peripheral calcification ring with central low-density organic core. Partial mineralization.
Distinct Features
Central-peripheral density difference on CT. Incomplete shadowing on US may occur. More difficult to detect on plain radiograph.
Distinguishing Feature
LAMN shows mural curvilinear calcification and cystic dilatation. Appendicolith is an intraluminal round/oval calcified structure without accompanying cystic dilatation (unless obstructive appendicitis develops).
Distinguishing Feature
Mucocele shows cystic dilatation and low-density mucinous content. Appendicolith is an isolated calcified intraluminal structure, cystic dilatation is typically absent.
Distinguishing Feature
Lipoma is a fat-containing mass showing negative density (-70 to -130 HU) without calcification. Appendicolith shows high density (>100 HU).
Urgency
routineManagement
conservativeBiopsy
Not NeededFollow-up
no-follow-upAsymptomatic appendicolith does not require treatment and has no follow-up indication. Appendicolith detected with acute appendicitis directly affects the surgical decision — the risk of complicated appendicitis (gangrene, perforation, abscess) increases 2-3 fold in the presence of appendicolith and early surgical intervention is recommended. Response to antibiotic therapy is lower in appendicitis with appendicolith and conservative treatment failure rate is higher. Therefore, surgery (laparoscopic appendectomy) is preferred in acute appendicitis with appendicolith. When incidental appendicolith is detected, it may be appropriate to inform the patient about appendicitis symptoms.
The risk of developing appendicitis is increased in the presence of an appendicolith, and when it develops, the perforation rate is significantly higher (30-50%). Routine appendectomy is not recommended for asymptomatic incidental appendicoliths, but the patient should be informed. Early surgical intervention in appendicitis cases with appendicolith reduces perforation risk.