Intra-operative cone-beam computed tomography for detecting residual stones in percutaneous nephrolithotomy, a randomized controlled trial

Percutaneous nephrolithotomy is the standard surgical treatment method for
large kidney stones. Obtaining a stone-free status is the main goal of this
surgical procedure. However, residual stones remain in many cases where the
urologist expected to have reached a stone-free status. Partly because of this,
re-intervention rates are high and stone-free rates show room for improvement.
Cone-beam computed tomography (CBCT) allows for intra-operative cross-sectional
and threedimensional imaging of the urinary tract. In this way, any imaged
residual fragments can be extracted in the same procedure, expectedly leading
to increased single step stone free rates.

Determining the added value of cone-beam computed tomography in percutaneous
nephrolithotomy, by measuring differences in the stone-free rates for patients
with cases in which a cone-beam CT-scanner is used versus patients with cases
in which no cone-beam CT-scanner is used.

This study is a randomized-controlled trial. Patients will be randomized into
two even groups during their percutaneous nephrolithotomy. One group will
receive an intra-operative cone-beam CT-scan, whilst the other group will
undergo the standard procedure without an intra-operative CT-scan. The
randomization occurs at the end of the procedure, at the point where the
urologist would have otherwise terminated the procedure.

The intervention is an intra-operative cone-beam CT-scan. After performing the
intra-operative CT-scan, there is a possibility of either continuing the
procedure and possibly extracting extra residual fragments, or terminating the
procedure if no (retrievable) residual fragments are imaged.

The main risks for participating patients consist of an added radiation
exposure and added surgery time if allocated to the interventional group. The
added radiation exposure is calculated to be 1,5-2 mSv. Surgery time needed for
preparation, performing and interpreting an intra-operative cone-beam CT-scan
is around 8 minutes, according to our recently conducted pilot-study. If imaged
residual fragments are extracted, the median total extra surgery time needed in
that pilot-study was 20 minutes.
Patients will not know to which group they are allocated to until after the
surgery procedure, since they are under anesthesia during the randomization
process.