renal trauma and calculi

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1.Upper urinary tract trauma 2.Renal and ureteric calculi Dr.Aftab Qadir

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1.Upper urinary tract trauma2.Renal and ureteric calculi Dr.Aftab Qadir1.Renal traumaUp to 90% of renal injury is due to blunt injury10% of patients with significant abdominal traumaPre exisiting renal abnormalities e.g. vulnerable position Pediatric kidney is also more vulnerable

Imaging is done in patient gross haematuria or microscopic haematuria with other signs of renal damage e.g. shockhistory of sustained substantial trauma to the renal area

Vulnaerable (as with transplant kidneys, horseshoe kidneys and crossed fused ectopia , often combined with increased bulk (tumours, especially angiomyolipomas and renal cell carcinomas, cysts and hydronephrosis from any cause)more anterior location and proximity to the rigid superior iliac crest and spine2

Imaging IVUIt may offer confirmation for the presence of a functioning contra lateral kidneyThe absence of unilateral excretion suggests a major vascular injuryDisruption of the pelvicalyceal system may be seen as extravasation of opacified urine.One shot intravenous Urographyone-shot intravenous pyelographyThis procedure frequently consists of more than just one exposure and should include a scout radiograph as well as additional images obtained immediately after intravenous administration of iodinated contrast material and again 510 minutes later.IVU It has now largely been replaced by cross- sectional imagingprimary role for intravenous urography is the assessment of gross function and the evaluation of the uninjured kidney in hemodynamically unstable patients4

UltrasoundExtensively used in trauma.Subcapsular and perinephric haematoma can be seen Acutely seen as echo-poor areas, becoming more heterogeneous and echogenic with time. Disruption of renal parenchyma with capsular tears.Color flow and spectral Doppler may allow diagnosis of pedicle injuries. Significant renal injuries may be missed, with up to 80% of parenchymal lesions being overlooked.

Detecting hemoperitoneum US is well accepted as a method for detecting hemoperitoneum in patients with suspected intraperitoneal injuries following blunt trauma but is limited compared with CT in the evaluation of the renal parenchyma.6

Renal and perirenal hematoma after renal lacerationNo flow in the hematoma

7CTCurrently the imaging modality of choice Entire abdomen, including the liver and spleen evaluated for coexistent injuriesMultiplanar reformatted and three-dimensional imagesHaematoma may be parenchymal, subcapsular, perinephric or any combination of theseEarly and delayed scans are done

Early and delayed CT scans through the kidneys are necessaryMotion artifacts can be minimized with the shorter acquisition time8Subcapsular blood is seen as a cresentic low-density area following the convexity of the outer aspect of the renal cortex.

Perinephric haematoma surrounds the kidney as it enlarges mostly posterior, displacing the kidney forwards

If the collection is predominantly medial, pelviureteric disruption should be considered.

Renal lacerations/tears appear as irregular low-density linear areas crossing the parenchyma . Fractures are lacerations that extend from the hilum to the external surface of the kidney

Multiple renal fragments are referred to as a shattered kidney The commonest vascular injury to the kidney is renal artery disruption/avulsion, which appears as non-perfusion of the kidney.

There may be some peripheral perfusion preserved due to the early take-off of the capsular artery.


Renal contusion (category I) in a 46-year-old man who had sustained blunt abdominal trauma. Contrast-enhanced nephrographic-phase helical CT scan demonstrates a focal area of decreased contrast enhancement in the interpolar region of the left kidney (arrowhead).11

Subcapsular hematoma (category I) in a 40-year-old man who had sustained blunt abdominal trauma. Contrast-enhanced helical CT scan demonstrates a subcapsular fluid collection (straight white arrows) flattening the posterolateral contour of the left kidney. There is minimal cortical laceration (black arrow). Note also the subcutaneous emphysema in the left side of the back (curved arrow)12

Simple renal laceration (category I) in a 30-year-old woman who had sustained blunt abdominal trauma. Contrast-enhanced multidetector helical CT scan reveals a small, hypoattenuating laceration crossing the interpolar region of the left kidney (white arrow) associated with a limited perinephric hematoma. A hepatic laceration (black arrow) and hemoperitoneum in the Morrison pouch (arrowheads) are also seen.13

(a)Contrast-enhanced generalized-nephrographic-phase helical CT scan reveals what appears to be only a large perinephric hematoma (H) secondary to a distinct renal laceration (not shown). Because this is an early-phase image, there is no contrast material in the collecting system. The descending colon (C) is displaced anteriorly by the hematoma. (b)Excretory-phase CT scan demonstrates extensive extravasation of contrast-enhanced urine admixed with the hematoma, a finding that demonstrates that the laceration has disrupted the integrity of the collecting system.

urine extravasation from the collecting system in a 9-year-old boy who had sustained blunt abdominal trauma.


Subsegmental renal infarction (category I) in a 47-year-old man who had sustained blunt abdominal trauma. Contrast-enhanced CT scan demonstrates a sharply demarcated, wedge-shaped area of decreased attenuation in the interpolar region of the right kidney (solid arrow). Note also the evidence of subtle hemorrhage in the right renal hilum (open arrow).15

Major renal laceration without involvement of the collecting system (category II) in a 32-year-old woman who had sustained blunt abdominal trauma. Contrast-enhanced helical CT scan reveals a laceration in the posterolateral aspect of the middle portion of the left kidney (arrows) associated with perinephric hematoma. 16

Contrast CT showing large predominantly posterior perinephric hemorrhage.17

Demonstrating traumatic rupture of a pre-existing pelviureteric junction obstruction following relatively minor trauma. There is copious extravasation of urine and contrast medium18

Contrast CT showing a fracture through the centre of the kidney with considerable circumferential perinephric haemorrhage (A). Two months after conservative management there has been impressive healing of the kidney and resorption of most of the haemorrhage (B).19

Ruptured renal cyst with pericystic fluid20Most widely used imaging classification of renal injuries is by Federle. categorizing injuries into four groups (minor, major, catastrophic and injuries to the pelviureteric junction).

The American Association of Surgery (AAST) have described a surgical classification

Michael Federle placed renal injuries into four categories:Minor injury:renal contusion.intrarenal and subcapsular hematoma.minor laceration with limited perinephric hematoma without extension to the collecting system or medulla.small subsegmental infarct.

Major injury:major laceration into medulla or collecting system.segmental infarct.

Catastrophical injury:Maceration of the kidneyTotal devascularization due to arterial occlusion.

Rupture collecting system.

23American Association of Surgery of Trauma (AAST)

In grade I there is nothing wrong with the parenchyma, just contusion or subcapsular hematoma.Grade II and III injuries are either less or greater than 1 cm lacerations, but with no injury to the collecting system.Grade IV is injury to the collecting system or large lacerationsGrade V is a shattered or devascularized kidney.24

95% of renal trauma is represented by minor lacerations and parenchymal contusions and does not require surgery.Most major lacerations will heal without intervention, even with a shattered kidneyPerinephric collections of urine or blood will tend to resorb over time.Large and/or infected collections may be treated with percutaneous drainage.

Patient with car accident: renal contusion (arrow in a), multiple laceration involving the hilum (arrow in b) with hematoma inside the perirenal space (*), and a partial devascularization (arrow in c). Surgical treatment required nephrectomy was successful. In a different patient (d), a subcapsular hematoma (#) determines compression of renal parenchyma. Non operative management was successful.27

Contrast CT of traumatic renal arterial avulsion. The left kidney is completely non-enhancing (non-perfused). There is a small amount of blood along the line of the renal vessels and a modest haemorrhage related to the spleen.28

Stab wound resulting in laceration of the lower pole of the right kidney with considerable associated hematoma shown on contrast CT29Ureteric traumaconstitutes less than I % of urinary tract trauma. more frequent in children acquired through medical intervention, e.g. gynecological surgery for malignancy.On IVU there may be mild to moderate fullness of the pelvicalyceal system and extravasations at the site of the tearcontrast extravasations, formation of a urinoma and occasionally ureteric discontinuity. Fistulation into other structures may occur Unlike renal and bladder trauma it is usually penetrating. It is occasionally due to severe deceleration with avulsion, usually at the pelviureteric junction, less often the upper third of the ureter and very rarely elsewhere in community-acquired injuries30

Bilateral extravasation from the distal ureters following radical pelvic surgery. The ureters also show smooth tapered stricturing in the pelvis with bilateral hydronephrosis and dilatation of the proximal ureters, worse on the right31

Damage to the left ureter during pelvic surgery with severe distal ureteric stricturing, extravasation and fistulation into the vagina arrow indicates contrast in the vagina.32

69 year old male. Contrast enhanced (left) and delayed (right) CT scans demonstrating low density fluid around the left kidney and ureter, and contrast extravasation from the proximal left ureter33Complications in Renal InjuryEarly complications urinary extravasation and urinoma formation, delayed bleeding, infected urinoma, perinephric abscess, sepsis, arteriovenous fistula, pseudoaneurysm

Late complications include hydronephrosis, hypertension, calculus formation, and chronic pyelonephritisRecommended article Imaging of Renal Trauma: A Comprehensive Review Trauma Imaging

Current Role of Emergency US in Patients with Major Trauma

2.Renal and ureteric calculiRenal calculiForm due to minerals crystallizing out of urine in a normal urinary tract.Hyperealciuria is the most common Highly radiopaque, particularly calcium phosphate calculi. Small-bowel disease or resection predisposes particularly to the formation of oxalate calculi, which may have a speculated or punctate appearanceCalculus may become large and branching (staghorn, i.e. extending into adjacent calycesparticularly calciumnumber of causes hyperparathyroidismassociated with abnormal metabolic statespelviureteric junction obstruction.presence of infection37

Over 90% of calculi are radiopaque on plain filmsVirtually all are seen on CT

Small calculi that remain in the calyces are generally asymptomaticMigration of small calculi into the ureter is common and presents with colic.There is usually haematuria


Plain abdominal radiography assessing total stone burden, as well as the size, shapelocation of urinary calculiCalcium-containing are radiopaquethe progress of the stone can be easily monitored with a follow-up KUB

Many calcifications on the KUB radiograph are: phleboliths, vascular calcifications, calcified lymph nodes, appendicoliths, granulomas or even bowel contents.approximately 85% of all upper urinary tract calculiPleboliths demonstrates a lucent center43

Larger calculus in the left lower pole major calyx.44

Multiple punctate calculi in hyperoxaluria secondary to small bowel resection.45

Plain film showing large right staghorn calculus.46IVUThe traditional modality for investigating ureteric calculiIn most patients with ureteric colic there is some degree of obstruction, manifested by delay in the appearance of the nephrogram and contrast excretion into the pelvicalyceal system. The affected kidney is often modestly enlargedCalculi are seen as filling defects on the post contrast filmAcute ureteral obstruction causes an intense persistent nephrograms.CT scanning has replaced IVPThe delay varies from a few minutes to 24 h or more depending on the severity of the obstruction. There is generally some distension of the pelvis and the ureter down to the calculus, with a standing column of contrast in the ureter above the calculus. This is often best demonstrated on prone films and is usually relatively mild compared to the degree of dilatation that occurs in chronic obstruction. There may be extravasation of contrast from rupture of one of the fornices associated with high pressure in the obstructed system leading to pyelosinus and pyelolymphatic extravasation. The vast majority of calculi progress down the ureter into the bladder over a variable period of time; at least 95% of patients with calculi less than 4 mm diameter would he expected to pass them spontaneously. The time taken to pass the calculus relates to its size, calculi of 2 mm diameter taking a mean of 8 days, calculi over 4 mm a mean of 22.1 days. Calculi most commonly arrest (usually temporarily) over the sacrum, as the ureter crosses the iliac artery, or at the vesicoureteric junction in the intramural ureter, both sites of relative narrowing.

The main advantage of IVP is the clear outline of the entire urinary system that it provides, making visualization of even mild hydronephrosis relatively easy


Dense nephrogram with delay in appearance of contrast inthe left collecting system characteristic of high-grade obstruction (A). Eventually contrast outlines a mildly distended ureter down to a calculus atthe left vesicoureteric junction (B) with the calculus just visible on the plain film 48

Intravenous pyelogram (IVP) demonstrating dilation of the right renal collecting system and right ureter consistent with right ureterovesical stone.49

Pyelosinus extravasation (A) in high-grade obstruction with leakage of contrast around the upper pole calyces, which have become ill-defined. Contrast is entering the lymphatic vessels (arrow), pyelolymphatic extravasation. More profuse extravasation is occasionally seen with forniceal rupture (B)50

Full length film from an IVU series (A) showing stasis and mild fullness in the left ureter and considerable oedema around the vesicoureteric junction due to a small calculus visible on the plain film (B51

Radiolucent urate calculus, not visible on plain film, appearing as a well-defined filling defect in the collecting system of the left kidney (A). A larger mass is also visible distorting the left pelvicalyceal system. CT confirms that the small filling defect is a urate calculus (B) and the larger one a parapelvic cyst (C)52

CT showing modest perinephric stranding characteristic of significant obstruction from a ureteric calculus (A). In addition to these changes this second case shows a small fluid collection adjacent to the anterior lip of the renal hilum indicating a forniceal rupture (B). The acute generally mild, as demonstrated in this third example (C), but the asymmetry between the sides is useful (although this patient demonstrates a slightly full extrarenal pelvis on the asymptomatic side). There is mild perinephric stranding on the symptomatic (left) side but considerable ill-definition around the pelvis, suggesting some extravasation into the renal sinus. This can be seen to track down along the dilated ureter, giving it a shaggy appearance (D).53Ultrasound usually demonstrates mild hydronephrosis sensitivity (95%) but at the cost of a low specificity of around 67%Highly echogenic foci with dense distal acoustic shadowingVesicoureteric junctionrelies on indirect visualization clues to identify stonesless accurate than IVP or CT in diagnosis of ureteral stonesdoes not help in the evaluation of kidney function.UltrasoundA stone easily identified with renal ultrasonography but not visible on the plain radiograph may be a uric acid or cystine stoneThe resistive index is calculated as peak systolic velocity minus end-diastolic velocity divided by peak systolic velocity5435% of patients acute ureteral obstruction do not demonstrate any significant hydroureteronephrosisnot reliable for small stones smaller than 5 mmdependent on operator skill

Small calculus in the distal dilated ureter seen as an echogenic focus on ultrasound.57

Grades of hydronephrosis59

Ultrasound showing a relatively marked hydronephrosis60

Small solitary renal calculus on ultrasound seen as anechogenic focus with marked distal acoustic shadowing.61

MimmicsArrows mark a segmental artery.Arcuate artery (arrow). Note its orthogonal relationship to the ultrasound beam and its double-channel appearance.Renal pyramids. Echogenic tips of the renal pyramids as seen in mild hydronephrosisMilk of calcium cyst with reverberation echoes(The milk of calcium is typically seen as an echogenic layer of intracystic material, which reverberates and sometimes gravitates to the dependent portion of the cyst)Junctional parenchymal defect (arrow)62Sonographic Mimics of Renal Calculi

CT KUB is very good at picking up small and large calcified stones in the kidneysunenhanced CT scan of the abdomen and pelvis very narrow cuts taken through the kidneys and bladder areascontrast obscures calcific densitiesthe patients bladder is filled, which facilitates viewing the ureterovesical junctionAdvantages of CT scanningIt can reveal other pathology (e.g., AAAs,appendicitis, pancreatitis, cholecystis, ovarian disorders, diverticular disease, renal carcinoma).It can be performed quickly (< 5 min acquisition time)It avoids the use of IV contrast materials.The density of the stone can assist in predicting stone composition and response to shockwave lithotripsy.

Disadvantages of CT scanning include the following:It cannot be used to assess individual renal function or degree of obstruction.It can fail to reveal some unusual radiolucent stones, such as those caused by indinavir and atazanavir, which are typically invisible on the CT scan (though some serve as a nidus for deposition of calcium oxalate or calcium phosphate deposition and thus become radiopaque). Because of this possibility, IVP with contrast should be used for patients taking indinavir or atazanavir. Sulfadiazine stones are also difficult to visualize on CT because of relatively low attenuation.[24]It is relatively expensive.It exposes the patient to a relatively high radiation dose (and thus should not be performed on pregnant women).Precise identification of small distal stones is occasionally difficult.Stone size as measured on CT KUB correlates poorly with actual size of the stone measured after spontaneous passage.[25]For this reason, caution should be used in counseling patients on the likelihood of spontaneous stone passage when stone size is determined using CT-based measurement.Although CT scans can be used to estimate the overall size, width, and location of a stone, they can only approximate its shape.[26]Stone location can be described in anatomical terms, but the CT scan lacks the surgical orientation that most urologists prefer.It is not suitable for tracking the progress of the stone over time, supporting the recommendation for KUB radiography along with the CT scan.

65Spiral CT is now increasingly replacing the IVUsensitivity of 94%, and specificity of 97%exposes the patient to a significant radiation Essentially all ureteric calculi are radiopaque on CT Calculi usually demonstrate a rim of soft tissue, which helps distinguish them.The obstructed kidney may also be enlargedThere is often stranding within the perinephric fatThe pyramids may normally appear remarkably dense on unenhanced CT (white pyramid sign) CT has the potential advantage of making alternative relevant diagnoses (diverticulitis, appendicitis, cholecystitis, etc.) in patients with acute abdominal painperform the CT with the minimum mAs.avoid misdiagnosing iliac artery calcification or phleholiths as calculi.66

Bilateral calcific densities near the vesicoureteric junctions. Right calcific density (red arrow) is completely surrounded by a soft tissue density rim consistent with a ureteric stone surrounded by an oedematous ureter wall (soft tissue rim sign). The left calcific density (green arrow) cannot be a ureteric stone as it is completely surrounded by fat density and it is therefore a phlebolith.67

Computed tomography shows a stone, of calcific density, at the level of right distal ureter, which determinesperiureteralinflammation and produces a mild hydroureteronephrosis in the ipsilateral kidney.69

Non contrast helical CT scan of the abdomen demonstrating a stone at the right vesicoureteric junction.70Hydronephrosis and hydroureterMajor causes of obstructive hydronephrosis:Calculi-renal pelvic (hydronephrosis alone), uretericPelviureteric junction obstructionTumoursInflammatory mass lesions Retroperitoneal fibrosisPregnancy hydronephrosis and hydroureter.A large renal pelvis alone is not hydronephrosis, it may simply represent a prominent extrarenal pelvis, which is a normal variant Hydronephrosis is dilatation of the renal pelvis and calyces.With chronic obstruction the signs are more pronounced and diffuse cortical loss develops. 71on IVU as blunting of the fornicesPelviureteric junction obstruction is associated with isolated hydronephrosis but obstruction below the level of the pelviureteric junction is associated with some degree of ureteric distension

prolonged obstruction there may be almost complete cortical loss.

Spectral analysis of interlobar or arcuate arteries may demonstrate increase in the resistive index in the obstructed kidney. This reflects reduction in the blood flow and is seen in a number of other conditions, including acute renal parenchymal disease.

A resistive index above 0.70, or more than 0.08 more than the contralateral kidney, is suggestive of obstruction in the appropriate clinical situation.

Few Cases

Left simpleureterocelewith a calculus.75

Subcapsular hematoma (Page kidney) in a 30-year-old woman with a history of a seizure disorder who presented with right flank pain and hypertension. Contrast-enhanced spiral CT scan demonstrates a subcapsular fluid collection (H) flattening the right kidney. The patient underwent successful US-guided percutaneous drainage of the hematoma.76

What we see on the right is not a laceration, because it is not linear.It is not a contusion, because it is sharply demarcated.This is an post traumatic segmental infarction.77

Axial contrast-enhanced CT scan image in venous phase: Shattered kidney with ureteropelvic junction rupture and extravasation of contrast media and avulsion of renal hilum that devascularizes the kidney (grade V AAST renal injury)78

Renal hematoma and a small perirenal hematoma79Thank You