Objectives. To study, in a prospective fashion, acute traumatic effect
s on the gastrointestinal tract of patients treated by extracorporeal
shock wave lithotripsy (ESWL). Methods. Stool samples from each of 54
patients were tested before and after ESWL for conversion to hemoccult
positive. A minimum of one negative pre-ESWL stool guaiac test was re
quired for inclusion into the study. A minimum of two stool guaiac tes
ts were done after ESWL to verify negativity. Patients who converted t
o a positive hemoccult test after ESWL were then evaluated by colonosc
opy for the source of bleeding. Results. Fifty patients completed the
study. A single patient (2.0%) converted to a positive post-ESWL hemoc
cult test and was evaluated with colonoscopy. This patient was found t
o have two benign adenomatous polyps in the sigmoid and descending col
on after treatment for a left renal pelvis calculus. An additional pat
ient with a slightly positive post-ESWL conversion refused further eva
luation. The overall post-ESWL conversion rate to guaiac positive, the
refore, was less than 4% (2 of 51 patients). Conclusions. There is no
evidence of significant trauma or detectable bleeding in the normal ga
strointestinal tract caused by ESWL as measured by postprocedure stool
guaiac testing. Guaiac testing of the stool after ESWL may unmask pre
-existing gastrointestinal disease. Therefore a positive guaiac test a
fter ESWL warrants further evaluation. This study reaffirms that ESWL
is a safe, minimally invasive technique for the treatment of urolithia
sis, without significant adverse side effects on the gastrointestinal
tract. (C) 1997, Elsevier Science Inc, All rights reserved.