Editing Kidney stone disease (section)

=== Imaging studies ===
Calcium-containing stones are relatively [[Radiodensity|radiodense]] (opaque to [[X-ray]]s), and they can often be detected by a traditional [[radiography]] of the [[abdomen]] that includes the [[kidneys, ureters, and bladder x-ray|kidneys, ureters, and bladder]] (KUB film{{Clarify|date=February 2024}}).<ref name=Pietrow2006 /> KUB{{Clarify|date=February 2024}} radiography, although useful in monitoring size of stone or passage of stone in stone formers, might not be useful in the acute setting due to low sensitivity.<ref>{{cite journal |last1=Brisbane |first1=Wayne |last2=Bailey |first2=Michael R. |last3=Sorensen |first3=Mathew D. |date=November 2016 |title=An overview of kidney stone imaging techniques |journal=Nature Reviews. Urology |volume=13 |issue=11 |pages=654–662 |doi=10.1038/nrurol.2016.154 |issn=1759-4812 |pmc=5443345 |pmid=27578040}}</ref> Some 60% of all renal stones are radiopaque.<ref name=SmithCentennial2000 /><ref name=Bushinsky2007 /> In general, calcium phosphate stones have the greatest density, followed by calcium oxalate and magnesium ammonium phosphate stones. [[Cystine]] calculi are only faintly [[radiodense]], while [[uric acid]] stones are usually entirely [[radiolucent]].<ref name=Smith1999 />

In people with a history of stones, those who are less than 50 years of age and are presenting with the symptoms of stones without any concerning signs do not require [[Helical cone beam computed tomography|helical CT scan]] imaging.<ref>{{cite web|author1=American College of Emergency Physicians|title=Ten Things Physicians and Patients Should Question|url=http://www.choosingwisely.org/doctor-patient-lists/american-college-of-emergency-physicians/|website=Choosing Wisely|access-date=14 January 2015|date=27 October 2014|url-status=live|archive-url=https://web.archive.org/web/20140307012443/http://www.choosingwisely.org/doctor-patient-lists/american-college-of-emergency-physicians/|archive-date=7 March 2014|df=dmy-all}}</ref> A [[CT scan|computed tomography]] (CT) scan is also not typically recommended in children.<ref>{{cite web|title=American Urological Association {{!}} Choosing Wisely|url=http://www.choosingwisely.org/societies/american-urological-association/|website=www.choosingwisely.org|access-date=28 May 2017|url-status=dead|archive-url=https://web.archive.org/web/20170223133729/http://www.choosingwisely.org/societies/american-urological-association/|archive-date=23 February 2017|df=dmy-all}}</ref>

Otherwise a noncontrast helical CT scan with {{convert|5|mm|in|1|sp=us}} sections is the diagnostic method to use to detect kidney stones and confirm the diagnosis of kidney stone disease.<ref name=Pearle2007 /><ref name=Anoia2009 /><ref name=SmithCentennial2000 /><ref name=Fang2009 /><ref name=Miller2007 /> Near all stones are detectable on CT scans with the exception of those composed of certain drug residues in the urine,<ref name=Pietrow2006 /> such as from [[indinavir]].

Where a CT scan is unavailable, an [[intravenous pyelogram]] may be performed to help confirm the diagnosis of [[urolithiasis]]. This involves [[Intravenous therapy|intravenous injection]] of a [[Radiocontrast|contrast agent]] followed by a KUB film. [[Urolith]]s present in the kidneys, ureters, or bladder may be better defined by the use of this contrast agent. Stones can also be detected by a [[retrograde pyelogram]], where a similar contrast agent is injected directly into the distal ostium of the ureter (where the ureter terminates as it enters the bladder).<ref name=SmithCentennial2000 />

[[Renal ultrasonography]] can sometimes be useful, because it gives details about the presence of [[hydronephrosis]], suggesting that the stone is blocking the outflow of urine.<ref name=Pietrow2006 /> Radiolucent stones, which do not appear on KUB, may show up on ultrasound imaging studies. Other advantages of renal ultrasonography include its low cost and absence of [[Radiology|radiation exposure]]. Ultrasound imaging is useful for detecting stones in situations where X-rays or CT scans are discouraged, such as in children or pregnant women.<ref name="semins">{{cite journal | vauthors = Semins MJ, Matlaga BR | title = Management of urolithiasis in pregnancy | journal = International Journal of Women's Health | volume = 5 | pages = 599–604 | date = September 2013 | pmid = 24109196 | pmc = 3792830 | doi = 10.2147/ijwh.s51416 | doi-access = free }}</ref> Despite these advantages, renal ultrasonography in 2009 was not considered a substitute for noncontrast helical CT scan in the initial diagnostic evaluation of urolithiasis.<ref name=Fang2009 /> The main reason for this is that, compared with CT, renal ultrasonography more often fails to detect small stones (especially ureteral stones) and other serious disorders that could be causing the symptoms.<ref name=Cutler2007 />

On the contrary, a 2014 study suggested that ultrasonography should be used as the initial diagnostic imaging test, with further imaging studies be performed at the discretion of the physician on the basis of clinical judgment, and using [[ultrasonography]] rather than [[CT scan|CT]] as an initial diagnostic test results in less radiation exposure and equally good outcome.<ref>{{cite journal | vauthors = Smith-Bindman R, Aubin C, Bailitz J, Bengiamin RN, Camargo CA, Corbo J, Dean AJ, Goldstein RB, Griffey RT, Jay GD, Kang TL, Kriesel DR, Ma OJ, Mallin M, Manson W, Melnikow J, Miglioretti DL, Miller SK, Mills LD, Miner JR, Moghadassi M, Noble VE, Press GM, Stoller ML, Valencia VE, Wang J, Wang RC, Cummings SR | title = Ultrasonography versus computed tomography for suspected nephrolithiasis | journal = The New England Journal of Medicine | volume = 371 | issue = 12 | pages = 1100–10 | date = September 2014 | pmid = 25229916 | doi = 10.1056/NEJMoa1404446 | s2cid = 4511678 | url = https://escholarship.org/content/qt1cm5f8cd/qt1cm5f8cd.pdf?t=nwl44w | access-date = 25 September 2019 | archive-date = 14 March 2020 | archive-url = https://web.archive.org/web/20200314051953/https://escholarship.org/content/qt1cm5f8cd/qt1cm5f8cd.pdf?t=nwl44w | url-status = live }}</ref>

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File:Kidney stones abdominal X-ray.jpg|Bilateral kidney stones can be seen on this [[Kidneys, ureters, and bladder x-ray|KUB radiograph]]. There are [[phlebolith]]s in the pelvis, which can be misinterpreted as [[bladder stone]]s.
File:3mmstone.png|[[Transverse plane|Axial]] [[X-ray computed tomography|CT scan]] of abdomen without contrast, showing a 3-mm stone (marked by an arrow) in the left proximal [[ureter]]
File:Ultrasonography of renal stone located at the pyeloureteric junction.jpg|[[Renal ultrasonograph]] of a stone located at the pyeloureteric junction with accompanying hydronephrosis.
File:CT measurement of kidney stone in soft tissue and bone window.jpg|Measurement of a 5.6&nbsp;mm large kidney stone in soft tissue versus skeletal [[CT scan#Process|CT window]].
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