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ULTRASONOGRAPHY IN UROLOGY

A K Dalal, Dinesh Chaudhary, Palami Zaveri
Head, Dept. of USG; Association consultant USG; Hon. Radiologist, Jagjivanram Hospital.

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Over the period of last two decades, USG has come to be the mainstay in investigating urinary tract pathology. With the improvement in technology, resolution and variety of transducers, number of traditional IVP’s ordered have significantly reduced. Advantages of USG are its easy availability, flexibility, lack of ionizing radiation and lack of risk of a contrast reaction and facility of being done at bedside. Last but not the least the display of accurate anatomic information and sometimes physiological information (with colour flow imaging). A relative disadvantage of USG is that it is to some extent operator dependent and expertise of the operator can sometimes affect the diagnostic accuracy.

USG IN RENAL DISEASE

When a patient presents with any symptoms related to renal disease, urine examination and ultrasound examination of kidneys are the first of the investigations to be ordered. The reason for USG preceding X-ray KUB is that USG gives information about anatomic status of various parts of kidneys, i.e. renal cortex, collecting systems, ureters, bladder, leading to a reasonably accurate diagnosis. It also serves as a baseline comparative study for progression or regression of disease.

Following are the indications for sonography for kidney:-

1. Presence or absence of kidney
2. Location - Ectopic kidney
3. Calculus
4. Hydronephrosis
5. Renal cysts.
6. Renal cystic disease
7. Renal solid masses
8. Non-functioning kidney on IVP
9. Renal failure - i. chronic; ii. acute
10. Renal hypertension
11. Renal transplant
12. Post surgical complication
13. Localising calculus during lithotripsy and post lithotripsy follow-up.
14. Post DJ stent follow-up
15. Renal trauma
16. Urinoma or perinephric abscess/haematoma

RENAL CALCULUS DISEASE

With the advent of modern high resolution machines, the accuracy in identifying even a small renal calculus has significantly increased. As a result of this even a small calculus with its acoustic shadowing can be identified. Pelvic fat also being echogenic in nature can sometimes confuse the issue and make diagnosis of a small calculus difficult. However, the differentiating point is that a calculus is always in the collecting system and therefore would be surrounded by anechoic urine and frequently is associated with mild dilatation of calyx. Earliest of obstruction and dilatation of renal calyces and pelvis can be identified with USG and therefore it plays an important role in deciding the management of calculus disease. Follow-up of patients on conservative management for renal calculi is also greatly facilitated by ease of management. Once decision of conservative management is taken a follow-up USG at periodic interval is necessary until the calculus comes out to ensure that hydronephrotic changes are not increasing and renal cortical thickness is notsignificantly being compromised. Colour doppler and spectral analysis is sometimes helpful in determining need for surgical intervention. According to some authors if RI values on affected side is either more than 0.7 or more than 0.15 as compared to the normal side than surgical intervention is to be strongly considered to prevent significant permanent damage to the nephrons. USG is also used to localise calculus for lithotripsy and for follow-up of its complications.

Fig. 1: Kidney (N) in size showing dilatation of pelvicalyceal system and bright echo with acoustic show in Lt lower calyx - Lt renal hydronephtosis with calculus.	Fig.2: Inferior vena cava is dilated with irregular echogenic thrombus is seen in vena caval lumen - IVC Thrombus.
Fig. 3: On post-void film significant residual urine is seen and median lobe of prostate projecting in bladder cavity with smooth margins. BPH with significant median lobe enlargement.	Fig. 4: Dilated distal rt ureter is seen and bright echo is seen at rt V-U junction - Rt VU junction calculus with dilated rt ureter.
Fig.5: Lt epididymis is enlarged with thickened spermatic cord-free fluid is seen around it suggestive of Lt epididymitis.	Fig. 6: Partial stenosis of rt rental artery between hilum and mid region.
Fig. 7: Large hypoechoic lesion is seen occupying 5 x 3 cm area of prostate with few scattered echoes in it suggestive of prostatic abscess.	Fig. 8: Bladder wall is thickened and irregular echogenic mass is seen arising from bladder wall of size 8.5 cm Bladder tumour.
Fig. 9: Dilated distal rt ureter is seen.	Fig. 10: Dilated pelvicalyceal system is seen with bright echo in renal pelvis is seen - Hydronephrosis with calculus.

HYDRONEPHROSIS

Diagnosis of hydronephrosis can be accurately made by USG. It can be generalised or localised. At the time of initial examination grading of mild, moderate and severe, with or without thinning of renal cortex can be made along with the level of obstruction. Probable cause of obstruction i.e. calculus, tumour or extrinsic pressure is also looked for at the time of initial examination. This is then followed by further investigations such as IVP, CT scan, angiography etc. In pyonephrosis, the dilated collecting system is filled with low level echoic material which may require urgent drainage. USG guided PCN is sometimes needed especially in cases of non-functioning kidneys on IVP which will be discussed elsewhere.

RENAL CYSTIC MASSES

Simple renal cyst is a common occurrence ands easily diagnosed by USG. Aspiration of renal cyst is not necessary unless it is symptomatic. Complication of a cyst which may require aspiration are pain, haemorrhage and rarely a peripelvic cyst causing obstruction. In such cases USG guided aspiration of cyst is recommended. In some cases injection of sclerotic agent like tetracycline is used to prevent recurrence.

If a cyst is complex in nature, then FNAC is required to rule out malignancy.

Multiple cortical cysts suggest possibility of polycystic renal disease which can be classified as follows in adults.

Diffuse renal cystic disorder

1. Adult type of polycystic disease
2. Multiple cystic dysplasia
3. Medullary cystic disorder
4. Tuberus sclerosis
5. Von tripple Lindau syndrome
6. Medullary sponge kidneys

SOLID RENAL MASSES

Main role of USG in case of space occupying lesions in kidneys is to differentiate between cystic, complex and solid masses. Solid lesion can be benign or malignant but as a rule once a solid or complex lesion is diagnosed further work-up is necessary until a diagnosis is arrived at.

Solid Renal Masses

Benign Malignant

Adenoma Renal cell carcinoma and its

Angiomyolipoma extension in renal vein and

Oncocytoma IVC

Multilocular cystic nephroma Transitional cell carcinoma Wilm’s tumour Sarcoma Lymphoma Mets

 

MEDICAL RENAL DISEASE

USG is an investigation of choice to differentiate between acute and chronic renal failure. In CRF kidneys are small, contracted with thinned out renal cortex which is usually hyperechoic and shows loss of normal cortico-medullary differentiation. While in acute renal failure or acute nephritis kidneys are usually enlarged with thickened, oedematous cortex and relatively prominent and more hypoechoic pyramids. Surgical obstructive uropathy is also ruled out at the time of initial examination.

RENAL TRAUMA

In case of blunt abdominal trauma USG is helpful in diagnosing organ of involvement i.e. liver, spleen, pancreas and kidneys. In renal trauma fracture of parenchyma with haematoma in perinephric space and retroperitoneum is seen. Colour flow imaging can help in assessing the injury to vascular pedicle and extent of damage.

Once decision for conservative management is taken follow-up exams are necessary for assessment of complication and need for surgical intervention.

RENAL TRANSPLANT

USG and colour Doppler examination as the main investigations for evaluating the complication which can be acute or chronic.

Immediate post operative complication can be surgical and include obstruction, urinary leak or perinephric collection which can be either lymph, blood or infection. USG guided aspiration for diagnostic as well as therapeutic purpose are done at the same time. Vascular complication in the form of arterial or venous thrombosis are diagnosed by colour doppler examination.

Acute medical complications are acute tubular necrosis, rejection and drug toxicity. These are sometimes difficult to differentiate from one another, however, colour doppler examination does help at times in differentiating between these. USG guided biopsies may be required to make a conclusive diagnosis.

URETERS

Upper and lower ureters can be well visualised with relative ease on ultrasound examination, especially when dilated. On the other hand mid ureter is difficult to visualise. Full bladder is necessary to visualise the lower ureter and uretero-vesicle junction. Calculus impacted in U-V junction can be identified and with colour flow one can see the urine jet entering the bladder. Presence of urine jet on side of obstruction suggests patency of the ureter. Uretero-vesicle reflux can be suspected and diagnosed with help of colourdoppler examination, other abnormalities of ureter such as megaureter and ureterocele can also be diagnosed by USG. Extrinsic pelvic masses displacing or obstructing the ureter should be sought for during the evaluation of obstructive uropathy.

URINARY BLADDER

Urinary bladder can be examined by abdominal as well as endoscopic probes. For bladder outlet obstruction IVP has been completely replaced by ultrasound. Residual volume can be fairly accurately measured by ultrasound.

Following are the indications for bladder examination

1. Residual volume
2. Diverticuli
3. Bladder calculi
4. Chronic interstitial cystitis with diminished bladder capacity
5. Bladder tumour and invasion into bladder wall
6. Vesico-ureteric reflux
7. Ureterocoele
8. Post operative complications
9. Neurogenic bladder

PROSTATE

Evaluation of prostate has been greatly facilitated by modern high resolution trans-rectal probes. Incident of prostatic carcinoma increases with the advancing age and therefore in western countries PSA along with trans-rectal ultrasound has become the part of yearly routine check-up. Most of the prostatic carcinomas are hypoechoic in appearance with the result that sometimes it is not possible to differentiate from prostatitis. Clinical history, symptomatology and correlation with PSA is required to differentiate between the two and if PSA values are high than USG guided biopsy is warranted. If PSA is high and USG shows a suspected lesion then biopsy of the suspected lesion is obtained under ultrasound guidance but if ultrasound findings do not show a suspicious lesion then 4-6 quadrant biopsies from various areas of prostate in both the sides are taken to completely rule out prostatic carcinoma. Tumour infiltrating through prostatic capsule can be identified by TRUS. There have been studies where workers have believed that colour doppler may help in differentiating between prostatitis and carcinoma in few cases. Prostatic abscess can be drained under trans-rectal USG guidance.

Various pathologies of prostate identified by ultrasound are as follows:-

1. Prostatic carcinoma
2. Prostatitis
3. Prostatic abscess
4. Prostatic cyst
5. Mullerian duct cyst

URETHRA

Urethra can be dynamically evaluated during micturition by small part probe on penile shaft during micturition and by trans-rectal probe for evaluation of strictures to locate the upper and lower extent of strictures.

SCROTUM

With high-tech small part probes excellent anatomic visualisation of scrotal anatomy is now possible with the result that the following conditions can be recognised with ease.

1. Hydrocoele
2. Infection (Epididymo-orchitis)
3. Testicular tumours
4. Leukaemic infiltration in testes
5. Epididymal cysts
6. Spermatocoele
7. Varicocoele
8. Testicular torsion

USG IN INFERTILITY

With colour doppler diagnosis of clinically significant varicocoele has become easier. Colour flow imaging show presence of dilated, tortuous spermatic veins and spectral values show evidence of reversal of flow in spermatic veins on valsalva manoeuvre. Presence, location, size and morphology of testes and epididymis gives us an indication of spermatogenesis or obstructive pathology. Presence or absence of vas deferens, seminal vesicles and ejaculatory ducts can also be identified by ultra-sound.

ULTRASOUND GUIDED INTERVENTION

Ultrasound guided biopsies, drainage and intervention has become a part of state of art urology practice. Following procedures are usually done under ultrasound guidance:-

A. Biopsy

1. Renal
2. Renal space occupying lesion FNAC
3. Prostate
4. Transplanted allograft

B. Aspiration

1. Renal cyst (Only if symptomatic)
2. Perinephric collection
3. Prostatic abscess
4. Post operative collection
5. Scrotal cyst
6. Urinoma

C. Nephrostomy

D. Lithotripsy

COLOUR FLOW IMAGING

With high-tech colour doppler machines evaluation of vascularity of kidney, prostate and scrotum has been possible. Kidneys and organs with low resistance flow and approximately 20% of total cardiac output passes through renal arteries. In chronic renal failure and medical renal diseases the resistance to the flow increases and RI values go up beyond 0.7, suggesting presence of compromised renal junction. Following are the conditions in which colour doppler is helpful.

1. Renal artery stenosis
2. Renal vein thrombosis
3. Renal transplant complication
4. Medical renal disease
5. Renal transplant rejection
6. Obstructive uropathy
7. Renal masses
8. Extension of RCC in renal vein and IVC
9. Varicocoele
10. Testicular torsion
11. Testicular masses

REFERENCES

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9. Benson CB, Doubilet PM, Richae JP. Sonography of male genital tract. Am J Roentgenol 1989; 152 : 705-713.
10. Fitzgerald SW, Erickson S, DeWire DM, et al. Colour doppler ultrasound in the evaluation of adult acute scrotum. J Ultrasound Med 1992; 11 : 543-48.
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