View source for Renal ultrasound

==Background==
[[File:Urinary system.png|thumb|(1) Human urinary system: (2) kidney; (3) renal pelvis; (4) ureter; (5) urinary bladder (6) urethra. Additional structures: (7) adrenal gland; (8) renal artery and vein; (9) inferior vena cava; (10) abdominal aorta; (11) common iliac artery and vein; (12) liver; (13) large intestine; (14) pelvis.]]
*Bedside renal ultrasound has accepted use in the diagnosis of [[nephrolithiasis]]
*In comparison of diagnosis by CT vs. U/S (by EP) vs. U/S (by radiologist):<ref>Smith-Bindman R, Aubin C, Bailitz J, et al. Ultrasonography versus computed tomography for suspected nephrolithiasis. NEJM. 2014; 371(12):1100–1110.</ref>
**No difference in rate of missed high-risk diagnoses that resulted in complications (pyelo/sepsis/diverticular abscess)
**No difference in rate of serious adverse events, pain scores, return emergency department visits, or hospitalizations

==Indications==
*[[Flank pain]]
*Suspected [[nephrolithiasis]]
*Hematuria
*Dysuria
*Anuria

==Technique==
#Select probe
#*Curvilinear/large convex probe (phased array probe may substitute)
#Location
#*Right kidney
#**Patient supine
#**Probe in the right lower intercostal space in the midaxillary line
#*Left kidney 
#**Patient supine or right lateral decubitus
#**Probe in the lower intercostal space on the posterior axillary line
#**More cephalad and posterior than when visualizing the right kidney
#Scan entire kidney (through liver)
#*Longitudinal (long axis) and transverse (short axis) views
#Scan the [[Bladder ultrasound|bladder]]

==Findings==
[[File:Hydro.png|200px]]
*Hydronephrosis
**Mild: Distention of collecting system
**Moderate: Dilation of collecting system, rounding of calyces
**Severe: Dilated renal calyces and cortical thinning<ref>Cosby, K. (2006) Practical Guide to Emergency Ultrasound. Philadelphia, PA: Lippincott Williams & Wilkins pp. 237, 245-248</ref>
***“Bear claw” appearance
***Represents severe obstructive uropathy

==Images==
===Normal===
<gallery>
File:No hydro still.jpg|No hydronephrosis
</gallery>

===Abnormal===
<gallery>
File:Mild hydro.png|Mild hydro
File:Moderate hydro.jpg|Moderate hydro
File:Severe hydro still image.jpg|Severe hydro
File:Ultrasonography of renal stone located at the pyeloureteric junction.jpg|Ureteral stone located at the pyeloureteric junction with accompanying hydronephrosis
</gallery>

==Pearls and Pitfalls==
*Patients that are overhydrated, pregnant, or with a full-bladder may have mild hydronephrosis bilaterally without obstruction
*Underhydrated patients may not have hydronephrosis on initial renal scanning, despite obstruction
*Renal cysts can sometimes be mistaken for hydronephrosis
**Cysts are typically single, circular, and arise in the periphery of the kidney
**They can be multiple as in polycystic kidney disease

===Renal Cyst Classification===
*Bosniak I :Benign simple cyst with thin wall without septa, calcifications, or solid components. 
*Bosniak II: Benign cyst with a few thin septa, which may contain fine calcifications or a small segment of mildly thickened calcification.  Hyperdense cysts must be exophytic with at least 75% of its wall outside the kidney to allow for appropriate assessment of margins, otherwise they are categorized as IIF. 
**Bosniak IIF: Includes renal cysts with multiple thin septa, a septum thicker than hairline, slightly thick wall, or with calcification, which may be thick. It also includes intrarenal cysts larger than 3 centimetres (1.2 inches). Category IIF cysts have a 5-10% risk of being kidney cancer, and therefore follow-up is recommended every 6 months. 
*Bosniak III: Indeterminate cystic masses with thickened irregular septa with enhancement. 50 % of these lesions are ultimately found to be malignant.
*Bosniak IV: Malignant cystic masses with all the characteristics of category III lesions but also with enhancing soft tissue components on CT independent of but adjacent to the septa. 100 %of these lesions are malignant.

==Documentation==
===Normal Exam===
A bedside ultrasound was conducted to assess for hydronephrosis with clinical indication of left/right flank pain. The left kidney, right kidney, and bladder were identified in the transverse and sagittal plane. There was no hydronephrosis identified.
===Abnormal Exam===
A bedside ultrasound was conducted to assess for hydronephrosis with clinical indication of left/right flank pain. The left kidney, right kidney, and bladder were identified in the transverse and sagittal plane. There was mild/moderate/severe hydronephrosis identified on the left/right.

==Clips==
===Normal===
<gallery>
File:No hydro.gif
</gallery>

===Abnormal===
<gallery>
File:Mild hydro.gif|Mild hydro
File:Moderate hydro clip.gif|Moderate hydro
File:Severe hydro.gif|Severe hydro
</gallery>

===Pitfall===
<gallery>
File:Nonobstructing stone.gif|Nonobstructing stone
File:Color flow kidney no hydro.gif|Using color flow to determine vasculature vs hydro
</gallery>

==External Links==
*[http://www.sonoguide.com/renal.html Sonoguide: Renal Ultrasound]

==See Also==
*[[Nephrolithiasis]]
*[[Flank pain]]
*[[Ultrasound (main)]]

==References==
<references/>

[[Category:Ultrasound]]
[[Category:Radiology]]
[[Category:Renal]]