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An enterolith is a stone-like concretion formed within the intestinal lumen by precipitation of mineral salts or inspissated intestinal contents around a nidus (such as undigested food, foreign body, or suture material).

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It may be primary (formed within the intestine) or secondary (originating outside and entering the bowel, e.g., gallstone ileus).

Classification

Etiological classification:

Type Description
Primary Enterolith Formed within the intestinal lumen, typically in areas of stasis or abnormal motility.
Secondary Enterolith Formed outside the bowel and then enters it (e.g., gallstone migrating through a biliary-enteric fistula, renal stone eroding into bowel).

Classification

Type Composition Imaging Characteristic
True Enteroliths Mineral salts (calcium phosphate, calcium oxalate, magnesium ammonium phosphate) Usually radio-opaque on X-ray
False Enteroliths (Phytobezoars, Fecaliths, etc.) Indigestible material (vegetable fibers, feces, hair) Often radiolucent, may be visible on CT or USG

Etiopathogenesis

  1. Stasis of intestinal contents → prolonged contact time.
  2. Bacterial overgrowth and pH alteration → precipitation of bile acids, calcium, and phosphate.
  3. Concentric lamellated deposition → formation of a stone-like mass (enterolith).
  4. Growth leads to partial or complete obstruction or ulceration.

Sites of Formation

Clinical Presentation