renal trauma and calculi

1.Upper urinary tract trauma2.Renal and ureteric calculi

Dr.Aftab Qadir

1.Renal trauma• Up to 90% of renal injury is due to blunt injury

• 10% of patients with significant abdominal trauma

• Pre 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. shock

• history of sustained substantial trauma to the renal area

Imaging

IVU

• It may offer confirmation for the presence of a functioning contra lateral kidney

• The absence of unilateral excretion suggests a major vascular injury

• Disruption of the pelvicalyceal system may be seen as extravasation of opacified urine.

One shot intravenous Urography

Ultrasound

Extensively 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

CT

• Currently the imaging modality of choice

• Entire abdomen, including the liver and spleen evaluated for coexistent injuries

• Multiplanar reformatted and three-dimensional images

• Haematoma may be parenchymal, subcapsular, perinephric or any combination of these

• Early and delayed scans are done

• Subcapsular 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.

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).

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)

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.

(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.

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).

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 posterolateralaspect of the middle portion of the left kidney (arrows) associated with perinephric hematoma.

Contrast CT showing large predominantly posterior perinephric hemorrhage.

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

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).

Ruptured renal cyst with pericystic fluid

Most 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

American Association of Surgery of Trauma (AAST)

• 95% of renal trauma is represented by minor lacerationsand parenchymal contusions and does not require surgery.

• Most major lacerations will heal without intervention, even with a shattered kidney

• Perinephric collections of urine or blood will tend to resorb over time.

• Large and/or infected collections may be treated with percutaneous drainage.

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.

Stab wound resulting in laceration of the lower pole of the right kidney with considerable associated hematoma shown on contrast CT

Ureteric trauma

• constitutes 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 tear

• contrast extravasations, formation of a urinoma and occasionally ureteric discontinuity.

• Fistulation into other structures may occur

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 right

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.

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 ureter

Complications in Renal Injury

Early 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 pyelonephritis

Recommended article

• Imaging of Renal Trauma: A Comprehensive Review

• http://pubs.rsna.org/doi/full/10.1148/radiographics.21.3.g01ma11557

• Abdominal Trauma Imaging

• http://www.intechopen.com/books/abdominal-surgery/abdominal-trauma-imaging

• Current Role of Emergency US in Patients with Major Trauma

• http://pubs.rsna.org/doi/full/10.1148/rg.281075047

2.Renal and ureteric calculi

Renal calculi

• Form 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 appearance

• Calculus may become large and branching (staghorn, i.e. extending into adjacent calyces

• Over 90% of calculi are radiopaque on plain films

• Virtually all are seen on CT

• Small calculi that remain in the calyces are generally asymptomatic

• Migration of small calculi into the ureter is common and presents with colic.

• There is usually haematuria

KUB• Plain abdominal radiography

• assessing total stone burden, as well as the size, shape

• location of urinary calculi

• Calcium-containing are radiopaque

• the 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.

Larger calculus in the left lower pole major calyx.

Plain film showing large right staghorn calculus.

IVU

• The traditional modality for investigating ureteric calculi

• In 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 enlarged

• Calculi are seen as filling defects on the post contrast film

• Acute ureteral obstruction causes an intense persistent nephrograms.

• CT scanning has replaced IVP

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

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 (B

• Ultrasound usually demonstrates mild hydronephrosis sensitivity (95%) but at the cost of a low specificity of around 67%

• Highly echogenic foci with dense distal acoustic shadowing

• Vesicoureteric junction

• relies on indirect visualization clues to identify stones

• less accurate than IVP or CT in diagnosis of ureteralstones

• does not help in the evaluation of kidney function.

Ultrasound

• 35% of patients acute ureteral obstruction do not demonstrate any significant hydroureteronephrosis

• not reliable for small stones smaller than 5 mm

• dependent on operator skill

Grades of hydronephrosis

• Sonographic Mimics of Renal Calculi

• http://www.jultrasoundmed.org/content/23/10/1361.full

• CT KUB is very good at picking up small and large calcified stones in the kidneys

• unenhanced CT scan of the abdomen and pelvis very narrow cuts taken through the kidneys and bladder areas

• contrast obscures calcific densities

• the patient’s bladder is filled, which facilitates viewing the ureterovesical junction

Advantages of CT scanning

• It can reveal other pathology (e.g., AAAs, appendicitis, pancreatitis, cholecystis, ovarian disorders, diverticulardisease, 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.

• Spiral CT is now increasingly replacing the IVU

• sensitivity 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 enlarged

• There is often stranding within the perinephric fat

• The pyramids may normally appear remarkably dense on unenhanced CT (white pyramid sign)

Bilateral calcific densities near the vesicoureteric junctions. Right calcificdensity (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.

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

Non contrast helical CT scan of the abdomen demonstrating a stone at the right vesicoureteric junction.

Hydronephrosis and hydroureter

Major causes of obstructive hydronephrosis:

• Calculi-renal pelvic (hydronephrosis alone), ureteric

• Pelviureteric junction obstruction

• Tumours

• Inflammatory mass lesions

• Retroperitoneal fibrosis

• Pregnancy hydronephrosis and hydroureter.

• 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

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.

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.

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)

Renal hematoma and a small perirenal hematoma

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