Despite the advent of sensitive and specific imaging modalities, plain film radiography, with or without the administration of intravenous contrast material, retains an important place in diagnostic uroradiology. The plain film of the abdomen or kidney, ureter, and bladder is most often performed with the patient in a supine position and the X-ray beam centred at the umbilicus to include the entire abdomen from diaphragm to pubic symphysis.

The plain film is most useful in demonstrating urinary tract calcifications, usually calculi, nephrocalcinosis, and tumoural or cyst calcifications. Large renal or retroperitoneal masses may be detected by the resulting displacement of adjacent structures. Additional findings from the visualized intestines and bones sometimes are valuable in directing the radiologist's attention to the correct diagnosis.

All contrast agents administered by the vascular route use an iodine-substituted benzene compound to impart radio-opacity. Although iodinated contrast agents are among the most commonly used and safest drugs, their administration may be associated with adverse reactions, which can be subdivided into minor and major types (Table 1) 460. Several of these reactions, such as hives, laryngeal and facial oedema, and bronchospasm, are anaphylactic in nature and may be prevented by pretreatment with corticosteroids or antihistamines. Other reactions including hypotension, pulmonary oedema, and dysrrhythmia, are not clearly allergic in nature. Patients with a history of drug allergy, shellfish seafood allergy, or asthma have a roughly two-fold increased risk of contrast reactions. This risk is three to four times as great (about 15–20 per cent) in patients who have experienced a previous contrast-related reaction. However, patients who have previously experienced a reaction to contrast media do not necessarily experience a reaction when re-exposed.

The incidence of contrast-associated reactions can be reduced by using a different imaging technique, using low-osmolar contrast agents, or by pretreatment with corticosteroids and/or antihistamines. If a patient has had a previous moderate or severe reaction, an alternative technique without intravascular contrast (sonography, radionuclide study, CT) should be performed if possible. Pain, nausea, vomiting, and some vascular and cardiac adverse effects are related to the hyperosmolality of conventional contrast agents. The incidence of these reactions can be reduced by using newer low-osmolar contrast agents. However, the cost of these new contrast agents is about 4 to 10 times that of the conventional agents. Suggested guidelines for the use of these low osmolar or non-ionic contrast agents are listed in Table 2 461. In patients with a strong allergic diathesis or a history of a reaction following contrast administration, corticosteroid pretreatment can be given. Premedication with corticosteroids (methylprednisolone 32 mg given 12 and 2 h prior to contrast exposure) reduces the incidence of all reactions requiring therapy by 42 per cent and reduces the incidence of major, life-threatening reactions by 62 per cent. However, steroid or antihistamine premedication does not lessen pain or discomfort during intra-arterial administration of contrast or lessen the effects of contrast agents on the heart.

Contrast agents are potential nephrotoxins and contrast nephropathy is the third most common cause of acute renal failure in the hospital patient population. Contrast nephropathy is defined as an increase in serum creatinine of 1 mg/dl and/or a 25 to 50 per cent decrease in glomerular filtration rate after intravascular administration of contrast material; it appears to be dose-related. In most patients, acute renal failure is self-limited, with creatinine values increasing within 24 h of exposure to iodinated contrast media, peaking at 2 to 5 days, and returning to normal by 7 to 12 days. Patients are not usually oliguric: oliguria indicates a poorer prognosis for recovery of normal renal function. Patients with diabetes, particularly the insulin-dependent type, and an elevated baseline creatinine level of over 3.5 mg/dl are particularly at risk of contrast-induced renal failure. Those with severe congestive heart failure, those receiving large or frequent doses of contrast material, and those with markedly elevated uric acid levels are also at a higher risk. Contrast nephropathy is probably not more common in patients with multiple myeloma, dehydration, hypertension, proteinuria, or in those above 65 years of age, unless they have pre-existing renal insufficiency. Treatment of contrast nephropathy is largely supportive and only in rare instances is short-term dialysis necessary.

The intravenous urogram or pyelogram is still the simplest and least expensive method of evaluating the urinary tract from kidneys to urinary bladder. Opacification of the renal parenchyma (nephrogram phase) can be seen within 1 to 2 min after administration of an intravenous bolus of contrast; the calices and renal pelvis (pyelogram phase) are visualized after about 3 to 4 min. The ureters and urinary bladder are sequentially imaged. The entire study can be completed in 20 min, although delayed images may be required to evaluate fully an obstructed system or a patient with renal insufficiency. Nephrotomography provides contiguous, planar coronal images of the kidneys and is most often performed as a part of intravenous urography when evaluating suspected renal masses. Retrograde pyelography is performed in the cystoscopy suite and entails cannulation of the ureteral orifice in the trigone of the bladder for retrograde opacifications of the ureter and intrarenal collecting system with contrast material. This study is often used in the evaluation of suspected intrarenal collecting system or ureteral pathology, when these structures are inadequately visualized by intravenous urography.

Contrast-supplemented radiographic studies for the evaluation of the lower urinary tract include voiding cystourethrography and retrograde urethrography. The former requires access to the urinary bladder, either by transurethral catheterization or by suprapubic needle puncture. Contrast material is then instilled by gravity and fluoroscopy is used to evaluate focal or diffuse bladder wall lesions, postvoid residual urine volume, contrast extravasation, or vesicoureteral reflux. Following complete bladder filling, micturition is initiated and images of the contrast-opacified urethra are obtained. Further evaluation of the male urethra can be accomplished by retrograde urethrography, which requires catheterization of the distal portion of the penile urethra using a small Foley catheter. Balloon insufflation in the fossa navicularis secures the catheter for controlled instillation of contrast into the anterior urethra by hand injection. Selective spot films guided by intermittent fluoroscopy will ensure that diagnostic information is obtained with minimal radiation to the gonads.

The use of ultrasound has increased in recent years as technological improvements have increased its versatility. Diagnostic ultrasound uses an acoustic wave generated by applying electrical energy to a piezoelectric crystal in a transducer. The wave propagates through the body and at the interface of tissues with different acoustic impedances, is reflected back towards the transducer, which also acts as an acoustic receiver. Ultrasound is safe in young or pregnant patients, is less expensive than most other technologies, and can be performed at the bedside. However, the quality of the results obtained is dependent on operator skill. In the genitourinary tract, ultrasound is commonly used for the investigation of renal masses, the detection of hydronephrosis or perinephric fluid collections, and in the evaluation of scrotal masses, male vasculogenic impotence, the prostate gland, and female pelvis.

CT uses highly collimated X-rays and computer-aided calculations of picture element (pixel) density to form a composite axial image. The advantage of CT compared with plain film imaging is its axial imaging format and superior contrast resolution: CT is better at differentiating tissues (air, water, fat, or bone) based on relative attenuation of X-rays. An orally administered contrast agent, such as dilute Gastrografin, increases the density of the bowel lumen and helps to distinguish bowel loops from enlarged lymph nodes or abnormal fluid collections. Optimal bowel opacification often requires administration of oral contrast at least 12 h before CT scanning, especially when an abdominal abscess is suspected. Intravenous administration of contrast is useful for differentiating vascular structures from lymph nodes and for detecting visceral mass lesions, which appear more or less opaque than adjacent normal parenchyma because of differential distribution and retention of contrast material. Major indications for using CT in urological practice include the evaluation of renal masses and staging of urinary tract neoplasms. CT is also useful in guiding needle or catheter placement for biopsy or drainage of a lesion or fluid collection.

Nuclear medicine plays an important role in the quantitative assessment of renal function. A radiopharmaceutical consists of a molecule or substance labelled with a radioisotope. The chemical substance determines the biodistribution of the radiopharmaceutical, while its detection depends on radioisotopic decay. The decay of commonly used radionuclides leads to emission of a &ggr;-ray, which can then be detected by gamma-camera. The renal excretion of intravenously administered radiopharmaceuticals provides a quantitative assessment of glomerular filtration rate, effective renal plasma flow, and renal transit times. Radiopharmaceuticals used for renography are excreted by glomerular filtration and/or tubular secretion. Technetium-99m diethylenetriaminepentaacetic acid is entirely excreted by glomerular filtration and is most often used to measure relative renal perfusion and glomerular filtration rate. Agents such as ¹³¹I or ¹²³I orthoiodohippurate are excreted by both glomerular filtration and tubular secretion and, being almost completely removed from the plasma during the first pass, can be used to measure effective renal plasma flow. Recently approved technetium-99m mercaptoacetyltriglycine may supplant iodine-labelled tracers. A third class of radiopharmaceuticals (technetium-99m dimercaptosuccinic acid) has a prolonged renal cortical transit time and can be used to image and characterize renal masses.

Magnetic resonance imaging (MRI) uses the inherent magnetic properties of hydrogen atoms (protons) to form images and, like ultrasound, does not expose the patient to radiation. The basic MRI system consists of a powerful magnet, gradient coils, a radiofrequency coil, and computers to perform data acquisition and processing. The radiofrequency coil generates energy, which excites proton nuclei aligned in the strong external magnetic field. When these protons return to equilibrium after radiofrequency transmission stops, the absorbed energy is emitted as a radiofrequency signal which is recorded and processed into spatial information. The gradient coils can be used to acquire images in multiple planes, in contrast to CT which is largely restricted to axial planar imaging. In the genitourinary tract and pelvis, MRI is particularly valuable in the staging of renal, bladder, prostate, and endometrial cancer and in the investigation of adrenal, uterine, and adnexal masses.

Although other imaging modalities have largely replaced angiography as the primary method of studying genitourinary tract anatomy, it retains an important role in both diagnosis and treatment in specific settings. Knowledge of vascular anatomy prior to nephrectomy for renal neoplasms or transplantation can best be obtained by angiography. Transcatheter arterial embolization of large hypervascular renal cell carcinomas facilitates tumour resection. Embolization techniques are also used to control post-traumatic or iatrogenic haemorrhage. Arteriography is the study of choice for diagnosing renal artery stenosis. Angioplasty of the stenosed vessel can, in many cases, effect a lasting cure. Most recently, angiography has found a place in the assessment and classification of vasculogenic male impotence.

The scope of interventional uroradiology has broadened considerably in recent years. Fluoroscopy, ultrasound, or CT can be used to guide percutaneous needle placement for aspiration and biopsy under local anaesthesia. Renal cysts and adrenal masses are routinely sampled using percutaneous needles, and retroperitoneal lymph nodes as small as 1 to 1.5 cm are amenable to CT-guided biopsy. Supplanting an operative procedure, transrectal ultrasound is being used increasingly to guide biopsy of the prostate gland. Perinephric, retroperitoneal, and pelvic fluid collections are routinely drained percutaneously. Antegrade needle puncture of the collecting system is performed as a prelude to several interventional procedures, including antegrade pyelography, ureteral pressure flow studies, placement of nephrostomy catheters and stents, basket stone extraction, and ureteral stricture dilatation. Certain procedures, such as extraction of stones or foreign bodies, percutaneous ureterorenoscopy, and percutaneous pyelotomy (endoscopic treatment of ureteropelvic junction obstruction) require the creation of a large-bore nephrostomy track to accommodate the rigid nephroscope. Such a track usually requires the placement of a balloon dilatation catheter over a guide wire and its subsequent inflation to the desired width. The nephroscope is introduced into the renal collecting system through a sheath, which is placed into the dilated track under fluoroscopic guidance.

Traumatic renal injuries can be subdivided into four categories on the basis of severity. Category I lesions (minor trauma) include parenchymal contusions and peripheral lacerations that spare the collecting system. Category II injuries (major trauma) include deeper renal lacerations that violate the collecting system and are often accompanied by extravasation of urine. Category III injuries or catastrophic trauma include injuries of the renal vascular pedicle and a shattered kidney. Ureteropelvic junction avulsion and lacerations of the renal pelvis compose the relatively uncommon fourth category of renal trauma. Most urologists and trauma surgeons agree that renal contusions and minor lacerations heal spontaneously without the need for surgery. Equally incontrovertible is the need to treat surgically category III and IV renal trauma. Controversy exists over the appropriate management of category II injuries. In addition to characterizing renal injuries, imaging should also provide important ancillary information which may affect treatment decisions. For example, it is important to determine the existence of underlying disease in the damaged kidney, the condition of the contralateral kidney, and the presence of associated injuries to the liver, spleen, pancreas, bowel, or chest. While availability on an emergent basis may vary, the principal imaging tests for evaluating renal trauma are intravenous urography, contrast-enhanced CT, and renal angiography. Ultrasound, scintigraphy, MRI, and retrograde pyelography play a minor role in the imaging of acute traumatic renal injury.

Despite suggestions that it should be replaced with contrast-enhanced CT, there is still a role for intravenous urography in the initial or definitive evaluation of certain trauma patients. In a clinically stable patient who has sustained blunt abdominal trauma and who is suspected to have suffered injury isolated to the kidney a normal urogram implies absence of significant renal trauma. In addition, intravenous urography can, in the interest of time, be abbreviated to a single-film study. The ‘one-shot’ study consists of a single abdominal film taken 10 to 15 min after administration of contrast material (50–100 ml of a 60 per cent solution of standard ionic or low osmolar contrast agent) through the patient's intravenous line. Normal contrast excretion by both kidneys provides reassuring evidence against renal artery thrombosis. In interpreting abnormal findings, limitations of urography should be noted. The finding of diminished contrast excretion is non-specific, since it may accompany a spectrum of renal injury from contusion to shattered kidney. Unilateral absence of excretion is usually an indication of severe renal injury, often indicating thrombotic occlusion of the main renal artery. Like diminished excretion, however, this finding also lacks specificity and may be the result of severe contusion or laceration, subcapsular haematoma, or pre-existing renal disease. Thus, when unilateral absence of contrast excretion is observed on intravenous urography, immediate CT or arteriography should be performed to exclude the possibility of vascular pedicle injury.

In addition to defining the nature and extent of renal injury, the major advantage of CT is that the abdomen and retroperitoneum can be evaluated concurrently for accompanying injuries. Traumatic lesions of the kidney that are well demonstrated by intravenous contrast-enhanced CT include contusions, superficial and deep lacerations, urinoma, intrarenal and perinephric haematoma, and infarction (Fig. 1) 1521,1522. CT is also superior to other non-invasive methods for demonstrating underlying renal disease in the injured kidney. As a general rule, when there is clinical suspicion of severe renal injury or multiple organ trauma, CT is the preferred initial imaging study. While some would argue in favour of proceeding directly to renal arteriography, unilateral renal non-visualization on intravenous urography may also be effectively pursued with contrast-enhanced CT. Renal arteriography is indicated if renal vascular pedicle injury is still in question despite evaluation with CT and may be preferred in patients who have suffered penetrating renal trauma, in whom the likelihood of vascular injuries, such as arteriovenous fistula, is greater. Arteriography is the study of choice when there is severe or persistent renal haemorrhage since embolotherapy may be of therapeutic value.

In the setting of acute pelvic trauma, common indications for the radiographic evaluation of the bladder and/or urethra include pelvic fracture, blood at the urethral meatus, perineal or scrotal haematoma, and vesicoprostatic displacement on digital rectal examination. Urethral continuity must be confirmed prior to transurethral catheterization of the bladder, since passage of a catheter through a partially ruptured urethra may complete the tear. Retrograde urethrography is the recommended imaging procedure. The patient is usually placed in a steep left posterior oblique position so that the male urethra can be imaged in profile; however, no patient should be moved for radiographic positioning until a plain radiograph of the pelvis has been consulted to exclude an unstable pelvic fracture. Partial or complete tears of the urethra are usually readily demonstrated as focal areas of contrast extravasation (Fig. 2) 1523. If the situation arises, retrograde urethrography can be performed after placement of a bladder retention catheter which does not drain urine. In this setting, it is imprudent to reposition or remove the transurethral catheter until the integrity of the urethra is investigated. Pericatheter retrograde urethrography is performed by wedging a 5 Fr paediatric feeding tube or a 16 gauge angiocath next to the Foley catheter. The tip of the tube should be just distal to the external sphincter prior to contrast injection and filming.

Traditionally, cystography has been the procedure of choice for the evaluation of bladder rupture. Intraperitoneal rupture can usually be distinguished from extraperitoneal rupture by noting the distribution of the extravasated contrast agent. If the paracolic gutters are opacified or if loops of small bowel are outlined by contrast material, intraperitoneal bladder rupture is diagnosed. There is debate on the role of contrast-enhanced CT in the evaluation of bladder injury (Fig. 3) 1524,1525,1526. CT performed after drainage of contrast material from the bladder is more sensitive than plain radiography after cystography for the detection of small or partially sealed bladder tears. CT can also be used to evaluate the rest of the pelvis for visceral and bony injury. A normal CT scan of the pelvis, including images of an emptied bladder that had been well distended with contrast-opacified urine, excludes bladder injury. When an optimal pelvic CT study is not feasible, static cystography is the most reliable method to evaluate bladder rupture. In general, bladder lacerations are not reliably assessed by excretory urography.

Imaging has a primary role in the initial staging and post-treatment follow-up of renal, bladder, prostate, and testicular neoplasms. Although no single imaging study can accurately evaluate the primary tumour, regional lymph nodes, draining venous tributaries, liver, lungs, and bones, contrast-enhanced CT approaches this ideal imaging method. For example, with respect to the initial staging of a renal cell carcinoma, CT can be used to assess the local extent of the tumour, retroperitoneal adenopathy, renal vein and caval involvement, and the liver, lungs, and adrenal glands for metastases. However, the limitations of CT for staging urological malignant disease should also be stressed. Retroperitoneal lymphadenopathy can only be diagnosed by CT when lymph nodes are greater than 1.5 cm in diameter. Non-enlarged nodes infiltrated by tumour may be detected by lymphangiography, which can then be used to direct percutaneous needle biopsy of the abnormal node. The most cephalad extent of intracaval tumour thrombus or direct invasion of the liver or spleen by a contiguous renal mass can be difficult to image by axial CT images alone. MRI can effectively address both of these problems because of its sensitivity to flowing blood and its multiplanar imaging capability (Fig. 4) 1527,1528,1529. Complete assessment of the spine, appendicular skeleton, and skull for metastases requires bone scintigraphy.

Contrast-enhanced CT and ultrasound have superseded radionuclide colloid liver scanning in the detection of hepatic metastases. Using ultrasound, the diagnosis of metastatic liver disease is suggested by an inhomogeneous pattern of echogenicity or by the presence of multiple, solid masses. Ultrasound or CT can also provide guidance for accurate and safe percutaneous needle biopsy of detected hepatic lesions. Although it is not universally accepted, MRI may be a more sensitive imaging study than either contrast-enhanced CT or ultrasound for the detection of liver metastases and it can be helpful in differentiating a common benign liver tumour, haemangioma, from metastases (Fig. 5) 1530,1531,1532.

The conventional methods used to stage prostate cancer locally, digital rectal examination and CT, are being challenged by endorectal ultrasound and MRI. A distorted or disrupted prostatic capsule imaged by either ultrasound or MRI, particularly if it is adjacent to an abnormal area in the peripheral zone of the gland, supports a diagnosis of tumour penetration through the capsule. Spread of tumour into the seminal vesicles can be evaluated by ultrasound, but sensitivity is low and the finding of irregularity of the seminal vesicle contour lacks specificity. Limited experience with MRI suggests that signal loss of the seminal vesicles on T&sub2;-weighted images may be a more accurate predictor of tumour extension. In contrast to the experience with prostate cancer, non-invasive imaging has largely been unsuccessful in predicting the depth of cancer invasion through the bladder wall and in differentiating recurrent bladder tumour from fibrosis following radiation therapy. The use of MRI of the bladder for these staging problems is increasing, but results are preliminary.

Radiographic imaging is indicated when diseases which may require surgical or radiological interventional treatment are suspected in a patient with urinary tract infection. In general, any patient with a urinary tract infection whose fever does not resolve after 5 days of adequate antimicrobial therapy, especially if there is a medical history of diabetes, immunosuppression, steroid use, renal stone disease, or previous urinary tract surgery, should undergo urinary tract imaging. These patients are more likely to have an infection requiring aspiration and drainage or nephrectomy to be adequately treated. Such diseases include renal abscess, perinephric abscess, infected renal cyst, pyonephrosis, emphysematous pyelonephritis, and xanthogranulomatous pyelonephritis. Prostatitis, prostatic abscess, pelvic abscess, or a fistula between bowel and urinary tract may also cause urinary tract infection refractory to antimicrobial therapy. The male patient with urinary tract infection and the female patient with recurrent infections may also benefit from imaging of the genitourinary tract. Female patients who improve clinically with appropriate antibiotic therapy need not undergo routine imaging.

Excretory urography and ultrasound are the initial imaging studies commonly recommended for investigation of urinary tract infection refractory to adequate antimicrobial therapy. Intravenous urography is an effective study for investigating complicated infections because it surveys the urinary tract from kidney to bladder. Stone disease and collecting system obstruction can be detected by either imaging modality, but papillary necrosis and structural abnormalities such as medullary sponge kidney, ectopic duplicated ureter, and ureterocele are more likely to be diagnosed by urography than by sonography. However, intravenous urography lacks sensitivity for certain infectious processes of the urinary tract: 75 per cent of patients with pyelonephritis and about 20 per cent of patients with perinephric abscess have a normal excretory urogram. Thus, ultrasound is preferred to urography when there is suspicion of renal or perinephric abscess. If an abscess is detected and, by its appearance, is amenable to treatment by catheter drainage, ultrasound can be used to guide aspiration and drainage. Voiding cystourethrography and the ¹¹¹In-labelled white blood cell scan are two imaging tests of value in certain clinical settings. The former is used to exclude vesicoureteral reflux as a cause of recurrent urinary tract infections. Reflux can be found in adults, particularly where there is a history of ureteral or bladder surgery. The ¹¹¹In-labelled white cell scan uses leucocytes which have been harvested from the patient and radiolabelled to localize to sites of acute infection as well as to the normal liver, spleen, and bone marrow. Imaging performed 24 h after white cell infusion detects acute abscesses with a sensitivity and specificity of 90 per cent, but false-negative results may be obtained in patients treated with antibiotics and in those with walled-off, chronic abscesses.

In the patient with flank pain and suspected urinary stone, imaging studies are aimed at locating the stone and assessing the coexistence and severity of collecting system obstruction. Since 90 per cent of urinary tract stones are radio-opaque, the abdominal plain film serves as a valuable initial imaging step. Visual inspection of specific areas on the abdominal radiograph is important since ureteral stones that obstruct tend to lodge in one of three sites of natural ureteral narrowing; the ureteropelvic junction, the inlet of the true pelvis, and the ureterovesical junction. The size and location of the ureteral stone affects the likelihood of spontaneous stone passage into the urinary bladder. As a general rule, 90 per cent of ureteral stones that are less than 4 mm in diameter and located in the lower ureter and about 80 per cent of stones of this size in the upper ureter will pass spontaneously. In contrast, 30 per cent of upper and 50 per cent of lower ureteral stones that are larger than 4 mm will pass spontaneously.

Intravenous urography and ultrasound are valuable tests for determining the existence and severity of collecting system dilatation associated with an obstructing ureteral stone. The classic findings of ureteral obstruction on intravenous urography are an enlarged ipsilateral kidney, a progressively denser nephrogram, delayed pyelogram, and ureteral dilatation to the site of obstruction (Fig. 6) 1533,1534,1535. Delayed films of the abdomen with the patient in a supine, prone or upright position may help demonstrate the site of obstruction, especially in high grade obstruction. The intravenous urogram may also demonstrate structural abnormalities of the urinary tract, such as medullary sponge kidney, pyelocaliceal diverticulum, ureteropelvic junction obstruction, ureteral stricture, or ureterocele, which predispose to stone formation or collecting system obstruction. On occasion, the patient may report relief of pain following intravenous urography when filtered and non-reabsorbed contrast material causes an osmotic diuresis, which facilitates stone passage. However, pain relief may also be a harbinger of forniceal rupture and urinoma formation, both of which can be detected by intravenous urography. Sonography is also useful in evaluating suspected urolithiasis. A stone usually appears as a highly echogenic focus that attenuates the ultrasonic beam, causing acoustic shadowing. Stones as small as 0.5 cm in diameter can be identified with currently available sonographic units. Ultrasound is used to evaluate renal lithiasis as well as the presence of pyelocaliectasis. Although an obstructing stone at the ureterovesical junction can occasionally be imaged by ultrasound, in the majority of adult patients, the ureter is not seen on routine ultrasound examination. Both false-negative and false-positive ultrasound results may occur when imaging for collecting system obstruction. The caliceal system may not be dilated early in the course of acute obstruction; repeat ultrasound examination 24 h later may be expedient if the initial examination does not confirm the presence of clinically suspected urinary tract obstruction. Conversely, a previously obstructed collecting system may remain dilated for long periods following spontaneous passage or fragmentation of a ureteral calculus, depending on the duration of obstruction. Dilatation of the collecting system is therefore not synonymous with obstruction; previous obstruction, vesicoureteral reflux, high urinary flow states (e.g., diuresis or diabetes insipidus), congenital megacalices, and congenital megaureter can be associated with hydronephrosis.

Retrograde pyelography and CT are occasionally useful, but are not routinely employed in the evaluation of the patient with suspected ureteral stone. When intravenous pyelography suggests ureteral obstruction but there is insufficient opacification of the ureter to suggest a cause, or when the intravenous pyelogram is normal or equivocal and flank pain persists, retrograde pyelography is indicated. A stone seen on retrograde pyelography can be removed, and a stent can be placed at the same time. CT, while rarely necessary in the acute setting, may be used to distinguish a radiolucent stone from a soft tissue density tumour or thrombus when a non-opaque intraureteral filling defect is identified on intravenous urography or retrograde pyelography. A stone is likely if the measured attenuation coefficient of the filling defect is markedly higher than soft tissue attenuation values.

Prostate cancer accounts for 21 per cent of cancers and 11 per cent of cancer deaths among men. Digital rectal examination is the traditional method of examining the prostate, and its simplicity and proven value in detecting prostate cancer makes it the pre-eminent screening examination. However, the effectiveness of the digital examination is limited by both its inherent restriction to examining only the palpable posterior portion of the gland and by its subjectivity. Two relatively new diagnostic tests complement the digital examination in the diagnosis and management of prostate cancer. Prostate-specific antigen is a serine protease glycoprotein produced in epithelial cells of the prostate. Serum levels of this antigen are elevated in patients with prostate cancer as well as in patients with a variety of benign prostatic diseases, such as acute bacterial prostatitis and benign prostatic hyperplasia. The latter is associated with an increase in serum prostate-specific antigen of approximately 0.3 ng/ml.g of adenomatous tissue; prostate cancer is associated with an increase in serum antigen levels of about 3 ng/ml.g of malignant tissue. While there is a good correlation between the clinical stage of prostate cancer and serum levels of prostate-specific antigen, the mean levels in patients with clinical stages A1 and A2 prostate cancer are not statistically different from those in patients with benign prostatic hyperplasia. In patients with prostate cancer treated either by surgery and/or radiation, monitoring of serum prostate-specific antigen levels is a useful way to evaluate recurrence.

Transrectal ultrasound examination of the prostate has changed the way in which the prostate is routinely examined and biopsied. High frequency transducers in small diameter probes are positioned in the rectum close to the prostate, permitting the examination of the entire gland. This method is most often used to characterize a palpable abnormality. It is a safe and effective means to guide outpatient prostatic biopsies without the need for an operative procedure. The majority of cancers arise in the peripheral zone of the prostate, which is composed of the posterior, lateral, and apical portions of the gland. Sonographically, cancers in the peripheral zone are most often hypoechoic (Fig. 7) 1536. Using transrectal ultrasound, cancers as small as 5 to 7 mm can be detected when the echogenicity of the cancer is sufficiently different from adjacent normal tissue to be distinguished. Detection of a hypoechoic lesion is now often used as an indication for biopsy, even though the likelihood of cancer is rather low, since a number of benign lesions, including small hyperplastic nodules, inflammatory foci, infarcts, cysts, or cystic atrophy may also appear hypoechoic. This non-specificity explains the cancer yield of about 30 per cent when hypoechoic lesions are biopsied. The yield of cancer from biopsy of a hypoechoic area increases to 71 per cent if both the digital rectal examination and the prostate-specific antigen level are also abnormal. Transrectal ultrasound may also have a role in following tumour response to therapy, since the irradiated and fibrotic prostate gland is particularly difficult to examine digitally. The effectiveness of transrectal ultrasound as a screening tool has not yet been established and has been the subject of controversy.

Ultrasonographically guided transrectal biopsies of the prostate can be safely performed on an outpatient basis. Prophylactic oral antibiotics and a cleansing enema are routinely administered before the biopsy. Both core biopsy and fine-needle aspiration biopsy can be performed with minimal patient discomfort. Reliable sampling of the prostate with an 18 gauge needle is aided by he use of a spring-loaded automatic firing biopsy gun, which rapidly advances the biopsy needle to a specified length while cutting a tissue core. By reducing crush artefact and minimizing needle deviation, this device substantially decreases the number of biopsies that yield insufficient tissue for diagnosis. Either the transaxial or the sagittal orientation can be used to remove a biopsy specimen of the prostate under ultrasound. The main advantage of the sagittal view is that the entire path of the needle can be readily tracked under real-time examination. While complications include transient haematuria, haematospermia, urinary retention, and fever, significant complications are unusual.

Endourology has evolved in the past decade as a technology for diagnosing and treating urological diseases in a manner that obviates the need for open surgery for a large number of patients. In the broadest sense the term refers to any endoscopic procedure or examination performed anywhere in the urinary tract from the urethra to the kidney. Recently however, it has come to refer to any diagnostic or therapeutic procedures performed on the kidney and upper collecting system by retrograde ureteroscopy or antegrade puncture.

Cystourethroscopy has been in use for well over 100 years, since the time when reflected candle light was the source of illumination through an endoscope. Since then, instruments have continued to improve. The majority are rigid, require various lens systems, vary from No. 15 French to No. 24 French in size, and contain continuous irrigation systems which allow bladder irrigation and aid illumination. The cystoscopes in use during the past 20 years have been of a fibreoptic nature, providing better visualization. Flexible cystoscopes offer less discomfort, especially in male patients, and also ensure visualization in all directions. In addition, use of a flexible cystoscope makes the lithotomy position unnecessary: the examination can be performed with the patient supine and without anaesthesia.

Many pathological entities can only be diagnosed by direct visualization of the bladder mucosa. Sources of bleeding can be ascertained, as can inflammatory lesions, and degrees of bladder trabeculation secondary to bladder outlet obstruction. The primary means of diagnosing transitional cell carcinoma of the bladder remains the cystourethroscope (Fig. 8) 1537. Tumours are visualized and can be biopsied through the working element of a cystoscope; tumours can also be resected under direct visualization.

The first transurethral ureteroscopy was reported in 1919, when an adult cystoscope was passed from the bladder into the renal pelvis of a child with megaureters. The ability to reach the upper ureter and pelvis from below has only been realized with the development of extended length endoscopes of fine calibre. It was not until 1961 that a 9 French fibreoptic ureteroscope was first used. Paediatric cystoscopes were first used to visualize the distal ureter, but now a wide range of extended length rigid and flexible ureteroscopes have been designed to provide excellent visualization of the renal calices, renal pelvis, and entire length of ureter. All endoscopes contain one fibreoptic image bundle and one or two fibreoptic illumination bundles. They are either passively or actively deflectable endoscopes. The small (7 French) passively deflectable endoscope can be advanced into the ureter like a ureteral stent, without dilatation of the ureteral orifice. This endoscope is only a diagnostic tool, lacking a working port for instrumentation. Its distal tip cannot be directed and thus, it is difficult to examine a calix; however, it is sufficient for examination of the ureter. The larger (9 French), non-steerable ureteroscope has a working channel through which a laser fibre or electrohydraulic instrument can be passed. Even larger (10–12 French) deflectable endoscopes are of more value in the examination of the entire collecting system and for stone fragmentation, biopsy, evaluation of haematuria, and for other therapeutic manoeuvres. The success rate for the diagnosis of haematuria by this approach is well over 50 per cent. Serious complications, such as perforation of a kidney or ureter can occur, but these are rare in the hands of an experienced endoscopist.

There are several essential elements necessary for ureteroscopic examinations (Fig. 9) 1538. Fluoroscopy is invaluable for manipulating the instrument within the collecting system. The patient is placed under general anaesthesia and given prophylactic broad-spectrum antibiotics. Cystoscopy is used to evaluate the ureteral orifice and retrograde pyelography is performed. A flexible guide wire is advanced through the orifice into the proximal ureter under visual guidance. With instruments larger than 7 French calibre, the ureteral orifice needs to be dilated. An 18 Fr angioplasty balloon is passed into the intravesical tunnel and the orifice is slowly dilated. Following withdrawal of the balloon, the ureteroscope is passed along the guidewire into the ureter. The entire collecting system can be examined under fluoroscopic control and contrast material may be injected to confirm the position of the instrument.

Drawbacks to flexible ureteroscopy include the inability to deliver adequate irrigation and the lack of a large bore working channel. Flexible instruments are available in a 7 to 12.3 French size range, and those that are 8.5 French to 12.3 French in size can be actively deflected in one or two directions. This capability for active deflection is the latest advance in ureteroscopic technology.

There are many therapeutic and diagnostic applications of this technology, including definition of ureteral or renal collecting system filling defects noted on urography, identification of bleeding points, treatment of stone disease, localization of a tumour, tumour surveillance and biopsy, and treatment of strictures in the upper tract (Fig. 10) 1539,1540. The overall complication rate of ureterorenoscopy is 15 to 25 per cent, the most common complication being minor extravasation of urine. Transient obstruction can occur, but actual stricture is rare (1 per cent). Postoperative fever occurs in a small number of patients.

Two contraindications to ureterorenoscopy remain: infection and severe haematuria. The irrigation port of the flexible instrument is insufficient to evacuate clot and provide sufficient flow of irrigant for visualization. However, visualization of the area of pathology has been reported in up to 93 per cent of patients. Experienced endourologists are able routinely to examine 75 to 85 per cent of the calices with currently available flexible ureterorenoscopes.

Endourology also includes percutaneous techniques that provide access to the urinary tract from an antegrade approach. Percutaneous placement of a nephrostomy catheter has replaced open surgery for decompression of an obstructed collecting system. In addition, a percutaneous puncture site can allow stones to be removed, fragmented, or ultrasonically desiccated, strictures to be cut, and in rare instances, superficial pelvic tumours to be fulgerated.

A rigid or a flexible nephroscope can be passed through a dilated percutaneous track. Rigid instruments cannot be passed into all the calices; flexible nephroscopes are now available which permit a complete inspection of the renal pelvis and collecting system to be undertaken through one nephrostomy track. The flexible instrument consists of a fibreoptic image bundle, two fibreoptic illumination bundles and an irrigation working channel with a tip deflection mechanism. The rigid 27 nephroscope, which fits into a 30 French percutaneous sheath is used in the majority of instances for the removal of large renal stones, either alone or in combination with extracorporeal shock wave lithotripsy. The flexible ureteronephroscope, which varies in size from 9.8 to 14.5 French, can accommodate a variety of baskets, biopsy forceps, and catheters.

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