Uro Radiology

URO-Radiology

by Dr Clarence Lei Chang Moh, FRCS Urol

Consultant Urologist

email: clarencelei@gmail.com

Urology imaging is an essential component of the assessment and management of urological disorders.  However, the history is still important as a working diagnosis can be made in majority of cases.  The urinary tract is also mainly retroperitoneal and in early stages of urological disorders, there are a few clinical signs.  Urological imaging is important to delineate anatomy and to have some idea of the function.  The important parts of the anatomy include the kidney, bladder and prostate as well as the entire urothelial system.  Twenty five percent of the cardiac output goes to the kidneys and therefore, angiography is important in specific situations.  

Urological imaging consists of the following:

(1)  Ultrasound of the urinary tract – kidney, ureter (upper and lower), bladder, prostate, posterior urethra.  Ultrasound is not optimal for the mid ureter & anterior urethra.  It does not give much direct assessment of function although a ureteric jet seen in the bladder from the ureteric orifice gives some idea of the function of that side of the urinary tract.

(2)  Plain x-rays – KUB (kidney, ureter, bladder).

(3)  IVU, Intravenous urogram.

(4)  CTU, Computerised tomographic urography; plain CTU is useful to diagnose stones & is imaging of choice   in an acute situation.

(5)  CTU with contrast; this would be essential to investigate cases of haematuria to see any abnormal vascularity of the urinary tract.

(6)  Radio isotope scans so as to see the perfusion and excretion of each part of the urinary tract.  This would be useful to see the differential function, especially with a view of nephrectomy.

(7)  Angiography either direct or CTA.  In an elective situation, it is useful to work up patients for donor nephrectomy so as to preferentially harvest the kidney with a single renal artery.  In emergency situations, it can be used for selective embolisation of a bleeder.

(8)  MRI, magnetic resonance imaging is useful for specific situations.  This is however quite dependent on technology and expertise.

Hazards of Urological Imaging

Radiation exposure has a teratogenic effect, esp during first trimester of  pregnancy. Radio contrast toxicity is a significant factor to consider. Therefore, ultrasound, plain x-ray or plain CT is usually preferred. There is a definite radiocontrast associated mortality, possibly around 1 in 40,000 (depending on contrast type).  For patients who have history of allergy, they should be pre-medicated with Prednisolone 40 mg 12 hours and 2 hours before the study.  When radio contrast studies are used, there should be ready facilities for emergency resuscitation.  In addition to radio contrast allergy, radio contrast is also  nephrotoxic.  Therefore, the serum creatinine (or preferably eGFR) should be assessed before the contrast study.   For patients who have an eGFR of <30 2="" a="" acidosis.="" administration="" after="" and="" are="" be="" before="" complication="" contrast.="" contrast="" days="" for="" has="" have="" high="" hydrated="" impairment="" indication="" lactate="" metformin="" nbsp="" o:p="" of="" on="" patients="" radio="" renal="" reviewed.="" should="" similarly="" stopped="" the="" to="" together="" use="" used="" well="" when="" who="" with="">

Nephrogenic systemic fibrosis is also a progressive disorder which occurs up to 5% of patients who are exposed to gadolinium, used in MRI.

Ultrasound is almost like a stethoscope for many doctors, especially urologists. It is often available in the clinic, emergency room, ward and operating theatre.  The kidneys are readily suitable for ultrasound. The ultrasound can pick up hydronephrosis, cysts, stones and masses.  Fluid would appear as hypoechoic and may be due to hydronephrosis or cysts.  For the occasional patients where differentiation is difficult, a plain CTU would be useful.  The upper ureter and lower ureter can be imaged readily if they are dilated due to any obstruction eg stone.  The bladder is readily seen by ultrasound to assess the bladder volume,  stones, bladder tumour, bladder wall thickness and any intraprostatic protrusion of the prostate (IPP). 

However, the IVU would give a better view of the collecting system.  Where stone treatment is contemplated, an IVU would usually be required to see the relation between the stone and the collecting system.  Occasionally, calcification seen on ultrasound may not be in the collecting system or may be in a calyceal diverticulum.  For stones in the mid ureter, a CTU (IVU if CTU not readily available) may be necessary to identify the stone.  IVU would also be necessary to look for urothelial tumours, although a CTU with contrast gives more idea about the vascularity of the lesion.

For congenital lesions, CTU or MRU would give a better definition of the urinary tract, in particular, duplex urinary tracts with ectopic  insertion, as a cause of incontinence.  The characteristics of the lesion on ultrasound (echogenicity) or CT (attenuation) would be give an idea of the underlying pathology e.g. fat in an angiomyolipoma would appear hyperechoic on ultrasound and a low attenuation on CT scan.

CT is better to assess the retroperitoneum e.g. lymphadenopathy from tumours or any tumours as a cause of ureteric obstruction. It would also give a better view of the extent of infiltration and the vascularity of any renal tumour. 

Diuretic studies are important when assessing patients with hydronephrosis.  Hydronephrosis may be obstructive, refluxing or non-refluxing and non-obstructive.  When the hydronephrotic system is full, IV Lasix will cause an increase of the distension if the system is obstructed. 

Radio isotope scans allow the perfusion, excretion of different parts of the urinary tract to be monitored with a count of its radiation.  It can also give a differential function of each kidney.  This information is important if a nephrectomy is to be considered.  If a diseased but good functioning kidney is removed, the patient may end up with dialysis.

Direct urography consists of the following:

(1)  Urethrogram, retrograde.

(2)  Bladder cystogram, micturiting cystourethrogram, MCU to see the various grades of reflux and also to see the urethra.  In neonates with bilateral hydronephrosis, the MCU is likely to show up a posterior urethral valve (PUV).

(3)  Pelvis, retrograde pyelogram, RPG, antegrade pyelogram, APG (the latter requires a puncture of the kidney).

Bacteria maybe introduced, with risk of sepsis.  Retrograde studies would usually have to be done with the use of a cystoscope. The urologist would ensure radiation protection for himself and the staff in the operating theatre.

Interventional uro-radiology may be performed by the radiologist or the urologist. For patients with ureteric obstruction by stone or tumour, the kidney function can be preserved with a percutaneous nephrostomy (PCN) or ureteric stenting.  Ureteric stenting can be performed by the antegrade or retrograde technique.  Puncture of the kidney may be performed with the help of ultrasound or fluoroscopy or combination of both.  Where there are stones in the kidney, the urologist can proceed to dilate the percutaneous tract and do PCNL, percutaneous nephrolithotripsy.  There are structures which can be damaged by a PCN, namely, the kidney, renal vessels, renal collecting system and the nearby organs, namely the colon and the pleura. 

Angiography is performed by direct puncture of the blood vessels or by CTA.  Generally, CTA has taken over the role of direct angiography as it is less invasive.  Angiography is useful for assessment of donor kidneys so that the kidney with the single renal artery is preferentially harvested for transplantation.  For patients with haematuria after trauma or PCNL, the affected bleeding vessel can often be embolised as a therapy for the bleeding.  This is usually performed by the interventional radiologist in the fluoroscopy suite.

Transrectal ultrasound, TRUS is an important modality of patients with LUTS, lower urinary tract symptoms and prostate cancer.  It is a relatively non invasive technique used in the urology clinic.  TRUS can look at the prostate size, prostate capsule, any prostate nodules (hypoechoic more likely to be cancerous), seminal vesicle invasion and also to look for urethral stones.  Prostate biopsies are also now routinely done in the urology clinic under TRUS guidance, taking 6 to 12 cores under local anaesthetic. 

In most medical centres, CT with CTA is a standard emergency investigation where there is suspicion of trauma to the urinary tract. It gives the maximal information in the shortest possible time and it is also useful to look for concomitant injuries in the abdomen.

SUMMARY:  Urology imaging is an important component for the management of most urological conditions.  Depending on the clinical problems, the least invasive & cost effective imaging is used.

24^th December 2008, 2 Oct  2013

University Alumni Reunions

Reunion Rendition

Every few years or so, we get together again,

An organizer is chosen and he starts the plan

'A reunion is coming; it'll be really grand,

Make plans to attend or you are not my friend! '.

The first reunion was somewhat bitter-sweet

After 20 years being apart, we decided to meet

The Mines was chosen as the place of retreat

We were anxious who would be there to greet

To our surprise the turn-out was not bad

After 20 years many of us have put on some fat

The lean boys once are now not so nice to look at! ,

The shapely girls before are now very much flat!

Three years later in Kucing we camped

Many were there too, the distance was pre-empt

Even for a weekend, its worthy to be cramped!

Friendship among us is definitely stamped

Ipoh, then Penang reunions were done

Each time we met, the evening was fun

Many bring spouses daughters and sons

The joy we have is second to none!

Do you think we can meet again and again?

Will our body be in sync with our brain?

How many more years you think to attain?

And shall we meet again and again?

By the fortieth year, I hope we will still be around,

Even if by then our knees are somewhat bound

Who cares if our waists and cheeks are somewhat round,

When we meet again as always it’s time to clown.

Are you eager to meet on the 50th year? ,

By then perhaps hearing aid is in our ear.

The crowd may be less as some may have fear

To travel far as the vision is no longer clear.

By 60th year do we dare to promise?

We will be around and not give this a miss?

Do we bother even if bladder is forever apiss!

To be with friends for an evening of bliss!

That night as we stand staring at that door,

Wondering, but not knowing what fate is in store…

Hands trembling, our hearts are beating fast…..

We will cross the threshold and step into our past…….

Lets say grace to the Almighty

For showering us with friendship till eternity………

Noor Othman

PUV posterior urethral valve

PUV, Posterior Urethral Valve

PUV, posterior urethral valve is the most important urological condition to diagnose in the neonatal male.  This is often suspected in the antenatal ultrasound of the mother.  The typical ultrasonic findings are: bilateral hydronephrosis, hydroureter and a distended bladder.  Occasionally, the posterior urethra would also be found to be distended.

Early surgery helps to reverse some of the obstructive uropathy. The patient can be catheterised with a feeding tube and a MCU, micturition cystourethrogram Xray done to confirm the diagnosis.  The urethral catheter should be left insitu after the MCU to drain the kidneys and also to allow the urethra to dilate to facilitate subsequent endoscopic treatment.

The definitive treatment of PUV is that of endoscopic fulgration in the operating theatre.

However, if there are noun paediatric instruments and the child is well (e.g. sepsis or renal failure), an emergency treatment is that of a vesicostomy.  The vesicostomy can be closed later on when the child is better, e.g. at the age of 4 years.

PROGNOSIS:

However, the PUV has already caused obstruction inuretro and more than 50% of patients have life long bladder dysfunction and some degree of kidney failure. 

Written by:

Dr Clarence Lei Chang Moh, Consultant Urologist.

Date: 20.9.2013

Enclosures: Xray (urethrogram)  of posterior urethral valve before and after treatment.

Dealing with Urolithiasis in Primary Care

DEALING WITH UROLITHIASIS IN PRIMARY CARE,

MIMS GP Workshop, Sandakan, 22 September 2013

by Dr Clarence Lei Chang Moh; email: clarencelei@gmail.com

Urinary stones affect 5 – 15% of populations (commoner in young men), with a 50% recurrence rate over 10 years. Ureteric colic is the most severe pain that men experience.  In addition, urinary stones cause a variety of symptoms including backache, suprapubic discomfort, dysuria and haematuria.

A basic investigation in any clinic is that of a urinalysis. I use a urinalysis machine with a print-out, charged at the  PHCSA rate of RM10. Metabolic investigations to establish the cause of the stone include the following: serum calcium, serum uric acid, serum creatinine, urinalysis and urine culture. About 1% of patients coming to a stone centre for lithotripsy are found to have hypercalcaemia due to primary hyperparathyroidism.  Urinary stones are confirmed by imaging. The initial imaging is usually that of an ultrasound of the urinary tract, which readily pick up stones in the kidneys and bladder.  Small stones in the ureter can be seen almost instantly with non-contrast CT urography, low dose radiation.  IVP is outdated unless CT is not available. I also ask for a KUB as baseline for follow-up. In older patients, bladder stones may be due to associated BPH, benign prostatic hyperplasia.

Medical therapy and stone prevention is mainstay of therapy in general practice. The preferred analgesia for ureteric colic is diclofenac rather than an opiate, which  causes sedation. Patients who are allergic to diclofenac may be given tramadol. Diclofenac is nephrotoxic, if used for more than a week.  For passage of ureteric stones the lower ureter may be relaxed  by  MET, medical expulsive therapy. This consists of alpha-blockers e.g. prazosin 1 mg bd, terazosin 2mg ON.  This is  taken at night to reduce postural hypotension.  Stones smaller than 6 mm do not usually require surgical intervention unless complicated by sepsis. Large untreated urinary stones will  eventually cause urosepsis.

The most important medical treatment for urinary stones is that of water therapy such that the patient produces 2 litres of urine per day.  The fluid intake of the patient depends on his environment.  There is no good evidence of advantages of specific juices or herbals.  A diet suitable for a recurrent stone former is one with less salt, less uric acid (red meat, nuts, protein), less oxalate (chocolate, spinach, concentrated tea) and normal calcium.

Uric acid stones can be effectively dissolved by medical therapy through urinary alkalinisation, keeping the pH around 7.  Uric acid stones comprise of about 20% of stones and are radiolucent but readily seen on ultrasound and non-contrast CT.  Even staghorn calculi of uric acid can be dissolved over a period of 6 months.  However, the patient should have good renal function to avoid accumulation of  potassium in PotCit and sodium  in sodium citrate.  Citrate in the urine reduces crystallisation of the calcium and uric acid and increases the stone free rate following lithotripsy, from 45.5% recurrence to 12.5% compared to a controlled group, over a 12 month period.

Stones may also be associated with infection especially in ladies; infective stones are faintly radio-opaque.  Stone and infection should be cleared by surgery, vigorous antibiotic therapy and followed by prophylaxis e.g.  nitrofurantoin 50mg on night for 6 months. In Malaysia stones are also not uncommon during pregnancy.  Unfortunately, radiation and lithotripsy are contraindicated in pregnancy. Obstructed ureters during pregnancy can be drained  with a percutaneous nephrostomy or ureteric stent, until the baby is delivered.

Indications for referral to a urologist would include: persistent severe colic for more than 48 hours, fever above 38ºC indicating urosepsis, stones which are large or multiple. Most stones are removed by ESWL, extracorporeal shockwave lithotripsy or endoscopic lithotripsy viz ureteroscopy or percutaneous nephrolithotripsy.  Only 5% of stones require open surgery eg huge stones or bladder stones in children, the later to avoid injury to the small urethra.