<s>
Pyelogram	O
(	O
or	O
pyelography	O
or	O
urography	O
)	O
is	O
a	O
form	O
of	O
imaging	B-Application
of	O
the	O
renal	O
pelvis	O
and	O
ureter	O
.	O
</s>
<s>
Intravenous	O
pyelogram	O
–	O
In	O
which	O
a	O
contrast	B-Application
solution	O
is	O
introduced	O
through	O
a	O
vein	O
into	O
the	O
circulatory	O
system	O
.	O
</s>
<s>
Retrograde	B-Algorithm
pyelogram	I-Algorithm
–	O
Any	O
pyelogram	O
in	O
which	O
contrast	B-Algorithm
medium	I-Algorithm
is	O
introduced	O
from	O
the	O
lower	O
urinary	O
tract	O
and	O
flows	O
toward	O
the	O
kidney	O
(	O
i.e.	O
</s>
<s>
Anterograde	O
pyelogram	O
(	O
also	O
antegrade	O
pyelogram	O
)	O
–	O
A	O
pyelogram	O
where	O
a	O
contrast	B-Algorithm
medium	I-Algorithm
passes	O
from	O
the	O
kidneys	O
toward	O
the	O
bladder	O
,	O
mimicking	O
the	O
normal	O
flow	O
of	O
urine	O
.	O
</s>
<s>
Gas	B-Algorithm
pyelogram	I-Algorithm
–	O
A	O
pyelogram	O
that	O
uses	O
a	O
gaseous	O
rather	O
than	O
liquid	O
contrast	B-Algorithm
medium	I-Algorithm
.	O
</s>
<s>
Unlike	O
a	O
kidneys	O
,	O
ureters	O
,	O
and	O
bladder	O
x-ray	B-Library
(	O
KUB	O
)	O
,	O
which	O
is	O
a	O
plain	O
(	O
that	O
is	O
,	O
noncontrast	O
)	O
radiograph	O
,	O
an	O
IVP	O
uses	O
contrast	B-Application
to	O
highlight	O
the	O
urinary	O
tract	O
.	O
</s>
<s>
In	O
IVP	O
,	O
the	O
contrast	B-Algorithm
agent	I-Algorithm
is	O
given	O
through	O
a	O
vein	O
(	O
intravenously	O
)	O
,	O
allowed	O
to	O
be	O
cleared	O
by	O
the	O
kidneys	O
and	O
excreted	O
through	O
the	O
urinary	O
tract	O
as	O
part	O
of	O
the	O
urine	O
.	O
</s>
<s>
If	O
this	O
is	O
contraindicated	O
for	O
some	O
reason	O
,	O
a	O
retrograde	B-Algorithm
pyelogram	I-Algorithm
,	O
with	O
the	O
contrast	B-Application
flowing	O
upstream	O
,	O
can	O
be	O
done	O
instead	O
.	O
</s>
<s>
An	O
injection	O
of	O
X-ray	B-Application
contrast	I-Application
medium	O
is	O
given	O
to	O
a	O
patient	O
via	O
a	O
needle	O
or	O
cannula	O
into	O
the	O
vein	O
,	O
typically	O
in	O
the	O
antecubital	O
fossa	O
of	O
arm	O
.	O
</s>
<s>
The	O
contrast	B-Application
is	O
excreted	O
or	O
removed	O
from	O
the	O
bloodstream	O
via	O
the	O
kidneys	O
,	O
and	O
the	O
contrast	B-Algorithm
media	I-Algorithm
becomes	O
visible	O
on	O
X-rays	B-Library
almost	O
immediately	O
after	O
injection	O
.	O
</s>
<s>
X-rays	B-Library
are	O
taken	O
at	O
specific	O
time	O
intervals	O
to	O
capture	O
the	O
contrast	B-Application
as	O
it	O
travels	O
through	O
the	O
different	O
parts	O
of	O
the	O
urinary	O
system	O
.	O
</s>
<s>
At	O
the	O
end	O
of	O
the	O
test	O
,	O
a	O
person	O
is	O
asked	O
to	O
pass	O
urine	O
and	O
a	O
final	O
X-ray	B-Library
is	O
taken	O
.	O
</s>
<s>
Immediately	O
after	O
the	O
contrast	B-Application
is	O
administered	O
,	O
it	O
appears	O
on	O
an	O
X-ray	B-Library
as	O
a	O
'	O
renal	O
blush	O
 '	O
.	O
</s>
<s>
This	O
is	O
the	O
contrast	B-Application
being	O
filtered	O
through	O
the	O
cortex	O
.	O
</s>
<s>
At	O
9	O
to	O
13	O
minutes	O
the	O
contrast	B-Application
begins	O
to	O
empty	O
into	O
the	O
ureters	O
and	O
travel	O
to	O
the	O
bladder	O
which	O
has	O
now	O
begun	O
to	O
fill	O
.	O
</s>
<s>
To	O
visualize	O
the	O
bladder	O
correctly	O
,	O
a	O
post	O
micturition	O
X-ray	B-Library
is	O
taken	O
,	O
so	O
that	O
the	O
bulk	O
of	O
the	O
contrast	B-Application
(	O
which	O
can	O
mask	O
a	O
pathology	O
)	O
is	O
emptied	O
.	O
</s>
<s>
plain	O
KUB	O
or	O
abdominal	O
X-ray	B-Library
;	O
</s>
<s>
an	O
injection	O
of	O
contrast	B-Algorithm
media	I-Algorithm
,	O
typically	O
50ml	O
;	O
</s>
<s>
delayed	O
abdominal	O
X-ray	B-Library
,	O
taken	O
at	O
roughly	O
15	O
minutes	O
post	O
injection	O
.	O
</s>
<s>
immediate	O
X-ray	B-Library
of	O
just	O
the	O
renal	O
area	O
;	O
</s>
<s>
5	O
minute	O
X-ray	B-Library
of	O
just	O
the	O
renal	O
area	O
.	O
</s>
<s>
15	O
minute	O
X-ray	B-Library
of	O
just	O
the	O
renal	O
area	O
.	O
</s>
<s>
If	O
compression	O
is	O
applied	O
:	O
a	O
10	O
minutes	O
post-injection	O
X-ray	B-Library
of	O
the	O
renal	O
area	O
is	O
taken	O
,	O
followed	O
by	O
a	O
KUB	O
on	O
release	O
of	O
the	O
compression	O
.	O
</s>
<s>
A	O
post-micturition	O
X-ray	B-Library
is	O
taken	O
afterwards	O
.	O
</s>
<s>
Therefore	O
,	O
they	O
are	O
often	O
now	O
replaced	O
by	O
ultrasonography	B-Application
and	O
magnetic	O
resonance	O
imaging	B-Application
(	O
MRI	O
)	O
.	O
</s>
<s>
Also	O
,	O
the	O
iodinated	B-Algorithm
contrast	I-Algorithm
medium	I-Algorithm
used	O
in	O
contrast	B-Application
CT	O
and	O
contrast	B-Application
radiography	O
can	O
cause	O
allergic	O
reactions	O
,	O
including	O
severe	O
ones	O
.	O
</s>
<s>
The	O
contrast	B-Application
dye	I-Application
may	O
also	O
be	O
toxic	O
to	O
the	O
kidneys	O
.	O
</s>
<s>
Metformin	O
use	O
:	O
Historically	O
,	O
the	O
drug	O
metformin	O
has	O
been	O
required	O
to	O
stop	O
48	O
hours	O
pre	O
and	O
post	O
procedure	O
,	O
as	O
it	O
known	O
to	O
cause	O
a	O
reaction	O
with	O
the	O
contrast	B-Algorithm
agent	I-Algorithm
.	O
</s>
<s>
However	O
,	O
guidelines	O
published	O
by	O
the	O
Royal	O
College	O
of	O
Radiologists	O
suggests	O
this	O
is	O
not	O
as	O
important	O
for	O
patients	O
having	O
<	O
100mls	O
of	O
contrast	B-Application
,	O
who	O
have	O
a	O
normal	O
kidney	O
function	O
.	O
</s>
<s>
If	O
kidney	O
impairment	O
is	O
found	O
before	O
administration	O
of	O
the	O
contrast	B-Application
,	O
metformin	O
should	O
be	O
stopped	O
48	O
hours	O
before	O
and	O
after	O
the	O
procedure	O
.	O
</s>
<s>
Contrast	B-Application
allergy	O
:	O
If	O
the	O
patient	O
has	O
any	O
previous	O
history	O
of	O
adverse	O
or	O
moderate	O
reactions	O
to	O
contrast	B-Algorithm
medium	I-Algorithm
.	O
</s>
<s>
It	O
is	O
done	O
in	O
cases	O
where	O
excretory	O
or	O
retrograde	B-Algorithm
pyelography	I-Algorithm
has	O
failed	O
or	O
contraindicated	O
,	O
or	O
when	O
a	O
nephrostomy	O
tube	O
is	O
in	O
place	O
or	O
delineation	O
of	O
upper	O
tract	O
is	O
desired	O
.	O
</s>
<s>
In	O
this	O
,	O
radiocontrast	B-Application
dye	O
is	O
injected	O
into	O
the	O
renal	O
pelvis	O
and	O
X-rays	B-Library
are	O
taken	O
.	O
</s>
<s>
A	O
retrograde	B-Algorithm
pyelogram	I-Algorithm
is	O
a	O
medical	B-Application
imaging	I-Application
procedure	O
in	O
which	O
a	O
radiocontrast	B-Application
agent	I-Application
is	O
injected	O
into	O
the	O
ureter	O
in	O
order	O
to	O
visualize	O
the	O
ureter	O
,	O
bladder	O
,	O
and	O
kidneys	O
with	O
fluoroscopy	O
or	O
radiography	O
,	O
using	O
plain	O
X-rays	B-Library
.	O
</s>
<s>
The	O
flow	O
of	O
contrast	B-Application
(	O
up	O
from	O
the	O
bladder	O
to	O
the	O
kidney	O
)	O
is	O
opposite	O
the	O
usual	O
outbound	O
flow	O
of	O
urine	O
,	O
hence	O
the	O
retrograde	O
(	O
"	O
moving	O
backwards	O
"	O
)	O
name	O
.	O
</s>
<s>
A	O
retrograde	B-Algorithm
pyelogram	I-Algorithm
may	O
be	O
performed	O
to	O
find	O
the	O
cause	O
of	O
blood	O
in	O
the	O
urine	O
,	O
or	O
to	O
locate	O
the	O
position	O
of	O
a	O
stone	O
or	O
narrowing	O
,	O
tumour	O
or	O
clot	O
,	O
as	O
an	O
adjunct	O
during	O
the	O
placement	O
of	O
ureteral	O
stents	O
.	O
</s>
<s>
Retrograde	B-Algorithm
pyelography	I-Algorithm
is	O
generally	O
done	O
when	O
an	O
intravenous	O
excretory	O
study	O
(	O
intravenous	O
pyelogram	O
or	O
contrast	B-Application
CT	O
scan	O
)	O
cannot	O
be	O
done	O
because	O
of	O
renal	O
disease	O
or	O
allergy	O
to	O
intravenous	B-Algorithm
contrast	I-Algorithm
.	O
</s>
<s>
Relative	O
contraindications	O
include	O
the	O
presence	O
of	O
infected	O
urine	O
,	O
pregnancy	O
(	O
because	O
of	O
radiation	O
)	O
,	O
or	O
allergy	O
to	O
the	O
contrast	B-Application
.	O
</s>
<s>
Because	O
a	O
pyelogram	O
involves	O
cystoscopy	B-Algorithm
,	O
it	O
may	O
cause	O
sepsis	O
,	O
infection	O
or	O
bleeding	O
,	O
and	O
may	O
also	O
cause	O
nausea	O
and	O
vomiting	O
.	O
</s>
<s>
An	O
intravenous	O
drip	O
is	O
inserted	O
and	O
a	O
person	O
is	O
given	O
some	O
sedation	O
before	O
a	O
cystoscope	B-Algorithm
,	O
which	O
is	O
a	O
flexible	O
tube	O
,	O
is	O
inserted	O
into	O
the	O
bladder	O
via	O
the	O
urethra	O
.	O
</s>
<s>
10	O
ml	O
of	O
contrast	B-Application
is	O
usually	O
injected	O
during	O
cystoscopy	B-Algorithm
,	O
which	O
is	O
where	O
a	O
flexible	O
tube	O
is	O
inserted	O
into	O
the	O
bladder	O
and	O
to	O
the	O
lower	O
part	O
of	O
the	O
ureter	O
.	O
</s>
<s>
Fluoroscopy	O
,	O
or	O
dynamic	O
X-rays	B-Library
,	O
is	O
typically	O
used	O
for	O
visualization	O
.	O
</s>
<s>
Risks	O
of	O
complications	O
of	O
the	O
procedure	O
includes	O
:	O
pyelosinus	O
extravasation	O
(	O
contrast	B-Application
going	O
into	O
renal	O
sinus	O
)	O
and	O
pyelotubular	O
(	O
contrast	B-Application
going	O
into	O
collecting	O
duct	O
)	O
reflux	O
of	O
contrast	B-Application
due	O
to	O
overfilling	O
of	O
the	O
urinary	O
system	O
.	O
</s>
<s>
IVP	O
is	O
an	O
affordable	O
and	O
useful	O
imaging	B-Application
modality	O
and	O
continues	O
to	O
be	O
relevant	O
in	O
many	O
parts	O
of	O
the	O
world	O
.	O
</s>
<s>
In	O
the	O
developed	O
world	O
,	O
however	O
,	O
it	O
has	O
increasingly	O
been	O
replaced	O
by	O
contrast	B-Application
computed	O
tomography	O
of	O
the	O
urinary	O
tract	O
(	O
CT	B-Algorithm
urography	I-Algorithm
)	O
,	O
which	O
gives	O
greater	O
detail	O
of	O
anatomy	O
and	O
function	O
.	O
</s>
<s>
IVP	O
was	O
previously	O
the	O
test	O
of	O
choice	O
for	O
diagnosing	O
ureter	O
obstruction	O
secondary	O
to	O
urolithiasis	O
but	O
in	O
the	O
late	O
1990s	O
non-contrast	O
computerized	O
tomography	O
of	O
the	O
abdomen	O
and	O
pelvis	O
replaced	O
it	O
because	O
of	O
its	O
increased	O
specificity	O
regarding	O
etiologies	O
of	O
obstruction	O
.	O
</s>
<s>
Etymologically	O
,	O
urography	O
is	O
contrast	B-Application
radiography	O
of	O
the	O
urinary	O
tract	O
(	O
uro	O
-	O
+	O
-graphy	O
)	O
,	O
and	O
pyelography	O
is	O
contrast	B-Application
radiography	O
of	O
the	O
renal	O
pelvis	O
(	O
pyelo	O
-	O
+	O
-graphy	O
)	O
,	O
but	O
in	O
present-day	O
standard	O
medical	O
usage	O
,	O
they	O
are	O
synonymous	O
.	O
</s>
