Computed tomography of renal emergencies: A comprehensive diagnostic guide for radiology residents

Table 1 Grading of renal trauma

Grade	Description	Imaging findings
I	Subcapsular hematoma +/- renal parenchymal contusion without definite laceration	Contusion: Ill-defined area of hypoattenuation on nephrographic phase; hyperdense on excretory phase due to retained parenchymal contrast. Subcapsular hematoma: Iso-to-hyperdense renal subcapsular collection
II	Renal parenchymal laceration of ≤ 1 cm depth with perirenal hematoma; absent urinary extravasation	Laceration: Linear area of hypoattenuation of ≤ 1 cm in length. Perirenal hematoma: Ill-defined stranding or hyperdense collection contained within the Gerota fasci. Absent urinary extravasation on excretory phase
III	Renal parenchymal laceration of > 1 cm depth without urine extravasation, active kidney bleeding contained within Gerota fascia, renal vascular pseudoaneurysm, or an AVF contained within Gerota fascia	Laceration: Linear area of hypoattenuation of > 1 cm in length. Vascular findings contained within the Gerota fascia: Pseudoaneurysm: Focal contrast-filled outpouching. AVF: Early renal venous opacification. Absent urinary extravasation on excretory phase
IV	Parenchymal laceration extending to the renal collecting system with urine extravasation, renal pelvic laceration +/- complete ureteropelvic disruption, segmental renal vein or artery AVF or pseudoaneurysm, active bleeding beyond Gerota fascia into retroperitoneal or peritoneal cavity, segmental or complete kidney infarction due to vessel thrombosis but without active bleeding	Urine extravasation on excretory phase. Segmental vascular involvement with findings similar to grade III, however, extending beyond Gerota fascia. Wedge-shaped hypoattenuations indicating renal infarcts
V	Shattered kidney with loss of identifiable parenchymal anatomy, devascularized kidney with or without active bleeding, lacerated main renal artery or vein, or an avulsed renal hilum	Active contrast extravasation on early phase with blooming on delayed phases indicating active vascular bleeding. Extensive ill-defined renal parenchymal hypoattenuation with disrupted anatomy

AVF: Arteriovenous fistula.

Table 2 Cho classification of arteriovenous fistula (create an image)

Type	Description
I	Less than four feeding arteries supplying a single dilated vein (arterio-venulous fistula)
II	Multiple feeding arterioles supplying a single dilated vein (arterio-venulous fistula)
IIIa	Multiple nondilated feeding arterioles supplying multiple nondilated venules (non-dilated arterio-venulous fistula)
IIIb	Multiple dilated feeding arterioles supplying multiple dilated venules (dilated arterio-venulous fistula)

Table 3 Imaging findings and management of infectious renal pathologies

Pathology	Imaging findings	Management
Pyelonephritis	Multifocal wedge-shaped hypoattenuation extending from the renal papilla to cortex. Round hypoattenuation rim-enhancing collections indicate abscess formation	Antibiotics and percutaneous or surgical abscess drainage
Emphysematous pyelonephritis	Gas locules within the renal collecting system with or without extension to the renal parenchyma, perinephric space, or pararenal space	Grade I, II: Antibiotics, percutaneous drainage of abscess, and decompression of urinary tract obstruction, if any. Grade III: Immediate nephrectomy and antibiotics. Grade IV: Same as grade I and II; nephrectomy if the initial treatment fails
Xanthogranulomatous pyelonephritis	Enlarged kidney with dilated renal calyces and a large staghorn calculus	Nephron-sparing nephrectomy in focal disease and total nephrectomy in diffuse involvement
Pyonephrosis	Complex fluid within the renal collecting system with or without internal septations	Urgent decompression with percutaneous or retrograde stent placement. Nephrectomy in advanced cases with irreversible renal damage