is a mineral concretion
formed anywhere in the gastrointestinal system
are uncommon and usually incidental findings but, once found, they
require at a minimum watchful
. If there is evidence of complications, they must be
An enterolith may form around a nidus
, a small
foreign object such as a seed, pebble, or piece of twine, that
serves as an irritant. In this respect, an enterolith forms by a
process similar to the creation of a pearl
An enterolith is not to be confused with a gastrolith
, which help digestion.
enteroliths are found by walking
pastures or turning over manure compost piles to find small
enteroliths, during necroscopy
increasingly during surgery for colic
Therefore, the incidence of asymptomatic enteroliths is
Equine enteroliths typically are smoothly spherical or tetrahedral,
consist mostly of the mineral struvite
(ammonium magnesium phosphate
have concentric rings of mineral precipitated around a nidus.
Enteroliths in horses
were reported widely in
the 19th century, infrequently in the early 20th century, and now
increasingly. They have also been reported in zebras: five in a zoo in California and one in a zoo in Wisconsin.
Struvite enteroliths are associated with
and mineral concentrations in the
California, struvite enteroliths are associated also with a
high proportion of alfalfa in the feed and
less access to grass pasture.
This association has been
attributed to the cultivation of alfalfa on serpentine soils
, resulting in high
concentrations of magnesium
, enteroliths are rare and may be
difficult to distinguish from gall
. Their chemical composition is diverse, and rarely can a
nidus be found. A differential
of an enterolith requires the enterolith, a normal
gallbladder, and a diverticulum
An enterolith typically forms within a diverticulum
. An enterolith formed in a
sometimes is known as a Meckel's enterolith. Improper use of
reported to cause enteroliths and/or medication
Most enteroliths are not apparent and cause no complications.
However, any complications that do occur are likely to be severe.
Of these, bowel obstruction
most common, followed by ileus
. Bowel obstruction
and ileus typically occur when a large enterolith is expelled from
a diverticulum into the lumen. Perforation typically occurs within
Most human enteroliths are radiolucent on plain X-rays. They
sometimes can be visualized on CT scans without contrast; presence
of contrast in the lumen may reveal the enterolith as a void. Most
often, they are visualized using ultrasound.
Although recent surveys of enterolith composition are lacking, one
early review notes struvite (as in equines), calcium phosphate
, and calcium carbonate
and reports choleic acid
. Deoxycholic acid
and cholic acid
have also been reported.
In simple cases of obstruction, where there are no complications, a
variety of non-surgical and surgical techniques are used to remove
the enterolith. These include crushing the enterolith and milking
it back to the stomach or forward to the colon, surgical removal
via an uninvolved segment of the gastrointestinal tract, and
of the involved segment.