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T14N - Text number 14 - Nursing
CALCULI
The cause is unknown. Calculi probably begin on
the renal papillae as small plaques which break free and act as
nuclei around which urinary salts are
precipitated.
The.size of a calculus varies from very small
»
gravel
to a large stag-horn stone which may fill the renal pelvis.
Calcium oxalate stones usually are small, dark, rough and
hard,
while calcium phosphate stones tend to be soft, white, chalky
and frequently stag-horn, in shape. Uric acid stones
commonly
are small and yellow but they may be of any color. Cystine
calculi have a waxy, almost transparent appearance. Calculi may
be multiple and bilateral. Migration of a stone may cause
obstruction with resultant, stasis, infection and
clinical
manifestations. Persistent or repeated obstruction leads to
pyonephrosis or
hydronephrosis.