Picture quiz: renal impairment

A 68 year old man with renal impairment was referred to a urology department. He had traces of blood and protein in his urine. He was clinically well and the examination was unremarkable.

The radiographs in figs 1, 2, and 3 were taken.

Questions

1. What are the investigations shown in figs 1 and 2?
2. What abnormality is seen in figs 1 and 2?
3. Fig 3 is an oblique view of the above investigation. What can you see?

Answers

1. Fig 1 shows kidneys, ureters, and bladder film (KUB); fig 2 shows an intravenous urogram (IVU).
2. Fig 1 shows a radio-opaque mass at the level of the left proximal ureter. Whether the mass is in the ureter or overlying it is not clear. Fig 2 shows the same radio-opaque mass in addition to the outline of the renal tract. The left renal tract proximal to the mass appears to be dilated.
3. The oblique view shows an mass 8 mm across in the left ureter causing partial obstruction. The calcified mass seen above is a mesenteric lymph node overlying the ureter.

From left to right: Fig1, Fig2 & Fig3.

Discussion

Renal stone disease has been affecting human beings for as long as records exist, and, in fact, much of the early history of surgery deals with stone disease and its disastrous consequences. The Hippocratic oath reflects this: "I will not cut, and certainly not those suffering from stone, but I will cede this to men who are practitioners of this art."

Many factors have been suggested to affect the incidence of stones including gender, race, geography, occupation, and the hardness of water. Overall the chance of a white man developing a renal stone by the age of 70 is almost 10%. Men are twice as likely as women to be affected, and the recurrence rate varies between 50% and 70% for the 20 years after the initial diagnosis.

Normal urine is composed of a complex solution of ions, proteins, and inhibitory substances. Should the delicate balance between them change, crystals form which precipitate into stones. Predisposing factors for stone formation include dehydration, chronic urinary infection, excess secretion of stone forming substances, foreign bodies, and diseased tissue.

Most stones (60%-70%) are composed of calcium oxalate. Stones of magnesium ammonium phosphate make up the about 15% to 20% and the rest are composed of calcium phosphate (5%), uric acid (5%) and finally cystine (1%). Overall about 90% of stones are radio-opaque.

Urinary tract stones may remain asymptomatic but they classically present with characteristics of ureteric colic. Patients have severe intermittent unilateral pain, radiating from the loin to the groin, and also the external genitalia and the inner thigh. Microscopic haematuria and, more rarely, macroscopic haematuria are often associated. Tachycardia is often present and examination may find tenderness in the loin or groin. If the patient is febrile, the diagnosis should be guided towards infection with obstruction or pyelonephritis. Excluding conditions that may present in a similar manner but which have devastating consequences if remain undiagnosed is fundamental. The most important are ruptured abdominal aortic aneurysm and ruptured ectopic pregnancy.

Investigations

Initial investigations should be tailored towards confirming the suspected diagnosis and screening for renal function and sepsis. Urine should always be cultured and serum calcium should be measured as it could expose surgically treatable hyperparathyroidism.

In the United Kingdom, intravenous urography is the imaging technique most commonly used for the diagnosis of suspected renal stone disease. Advantages of this procedure include the fact that is readily available in most accident and emergency departments and in addition, it is relatively accurate, economic and safe. Furthermore, the radiation dose is relatively small (depending on number of films taken) and it can demonstrate radiolucent stones as filling defects.

Unenhanced helical computed tomography scanning is the investigation of choice for a patient presenting with acute renal colic. It has a sensitivity of up to 98% for renal and ureteric stones, and it allows the detection of other pathology. Furthermore, scanning takes only 5 minutes to do, can provide digitally reconstructed images, and does not carry the risk of anaphylactic reaction. Conversely, computed tomography is considerably more expensive, requires a radiologist for accurate investigation, and is not readily available throughout the United Kingdom. Also, the dose of radiation is three times higher than the average radiation needed for intravenous urography.

Management

The immediate aim in the management of ureteric colic is to relieve pain and prevent permanent damage caused by either infection or the obstructed system. Non-steroidal anti-inflammatory drugs are usually effective for pain relief, if not, however, opioid analgesics should be given. Patients should take in adequate fluids.

At any point, conservative treatment should be abandoned if there are signs of infection (fever, tachycardia, increased pain, or increased white cell count) or if there are signs or renal impairment (increased creatinine or urea and electrolyte abnormalities). In the presence of these factors the obstruction or infection should be managed actively by the insertion of either a percutaneous nephrostomy tube or a double J stent, before definite treatment is considered.

It is widely accepted that stones less than 5 mm in diameter will usually pass spontaneously. If the stone is larger or if it is unlikely to pass further intervention should be considered.

In extracorporeal shock wave lithotripsy shock waves are directed towards the stone using ultrasound or fluoroscopic guidance. The treatment can be carried out with out the need of general anaesthesia, but more than one session could be necessary.

Stone can be accessed in other ways. They can be accessed directly using a ureteroscope or percutaneously and the stone can be retrieved using a basket. Alternatively, the stone can be fragmented using various electrohydraulic devices, pneumatic devices, and lasers.

Open surgery is hardly used nowadays (about 1% of cases). But laparoscopic removal is becoming increasingly popular for stones failing less invasive treatment.

Medical management has mainly a preventive role. Each treatment plan should be tailored to the needs of each individual patient, always having in mind the results of a metabolic and biochemical screen. In general, the best recommendation is to maintain a high daily intake of fluid and dietary fibre and decrease the intake of animal protein, dairy products, and salt.

Fig 3 Turbulence theory. Blood proximal to the cuff has a considerable amount of potential energy. When the cuff deflates, the blood enters the artery under the cuff (a system of low energy). This system of low energy absorbs the energy of the blood slowing the blood down and causing turbulent blood flow

Menelaos Philippou ,final year medical student, University of Manchester
Email: mphilippou@doctors.org.uk

Richard Napier-Hemy, consultant urologist, Manchester Royal Infirmary, Manchester


studentBMJ 2003;11:219-262 July ISSN 0966-6494

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