•Kidney Stones / Renal calculi
Very common finding on imaging
Kidney stones in the renal pelvis are usually asymptomatic
Pain comes with obstruction of the outflow of urine
Obstruction can be suggested by the presence of hydronephrosis
Kidney stones in the ureter can easily cause obstruction (cause pain to the patient). The jagged edges of this randomly shaped rock can cause injury while it slides down the ureter (that’s why we see hematuria on UA)
Symptomatic kidney stones are usually seen at the UPJ (ureteropelvic junction) – good place to look for stones
•Note: Imaging looking for kidney stones cannot be done with contrast. Contrast collects in renal system (that’s how it leaves the body). Contrast is bone-white and will obscure a bone-white object in the kidney/ureter/bladder (such as a stone)
•Future Urologists:
The magic number for stones is 5mm. Any stone bigger than 5mm probably won’t pass on it’s own and needs your help coming out!
•A “staghorn calculus” is a stone that takes up the entire renal pelvis (will be too big to even attempt to pass, but still may cause complications)
•Hydronephrosis
A blockage in the elimination of urine can exert pressure on the kidney
This causes swelling (hydronephrosis)
This can be unilateral or bilateral
•Bladder distention
Certain conditions affect urine elimination (prostate obstruction, dystonic bladder from neurologic injury or demyelinating conditions, etc.)
A distended bladder may eventually hold enough fluid to exert pressure on the renal system and affect renal function.
Remember: The kidney operates on “differentials,” if the pressure in the collecting system is too great, there is no differential, and the kidney (quite literally) cannot filter
A kidney injury of this type would be detailed as: Post-renal AKI (because the pathology is after the kidney)
A distended bladder is quite visible on imaging
A vesicular (meaning balloon-like) structure, with a uniform fluid inside (urine will have the same density throughout the bladder, so it appears as one color on imaging)
•Renal Masses
Renal “masses” are actually quite common
“Mass” is a non-specific word (we associate that term with neoplasm, but that isn’t the medical definition)
The majority of renal masses are cysts.
Future urologists: You may wish to become comfortable with “simple cysts” and “complex cysts” (see the Bosniak classification). Complex cysts require further work-up.
Renal malignancies can be identified on imaging (as a large highly suggestive mass, or a complex cyst with suspicious features)
•The associated images here are from the same patient at different levels. Notice how being able to see more of the structure is helpful in identifying what you are looking at. Notice how images may be clearer from the axial or coronal views. Note: Images have different “views” (different brightness/contrast settings that are pre-set into the software), that can really help identify certain structures.
•Official Radiology Read:
IMPRESSION:
1. Complex cystic lesion in the right lower renal pole measuring 3.4 cm, highly suspicious for malignancy (Bosniak IV).
2. Additional bilateral renal cystic lesions measuring up to 1.2 cm without complex features, most likely benign cysts. Metastatic disease is felt to be a less likely consideration.
3. Nonspecific retroperitoneal, gastrohepatic, and porta hepatis lymph nodes measuring up to 1 cm. Findings may be reactive although metastatic adenopathy cannot be entirely excluded.
4. A 1.4 cm lesion in the left lower renal pole contains macroscopic fat, compatible with angiomyolipoma.