See Chapter 2 – general contraindications to intravenous (i.v.) water-soluble contrast media and ionizing radiation. In patients with contrast medium allergies alternative modalities such as ultrasound or MR can be considered. Patients with impaired renal function, particularly those with diabetes should be prepared with oral or intravenous hydration, or an alternative imaging modality considered. See Chapter 2.

The examination should not proceed further until these images have been reviewed by the radiologist or radiographer and deemed satisfactory.

Technique

Venous access is established. The gauge of the cannula/needle should allow the injection to be given rapidly as a bolus to maximize the density of the nephrogram.

Images

1. Immediate film. AP of the renal areas. This film is exposed 10–14 s after the injection (approximate ‘arm-to-kidney’ time). It aims to show the nephrogram at its most dense, i.e. the renal parenchyma opacified by contrast medium in the renal tubules. Tomography may assist in evaluation of the renal outline or possible masses (or ultrasound if subsequently available).

2. 5-min film. AP of the renal areas. This film gives an initial assessment of pathology – specifically the presence or absence of obstruction before administering compression.

A compression band is then applied positioned midway between the anterior superior iliac spines, i.e. precisely over the ureters as they cross the pelvic brim. The aim is to produce pelvicalyceal distension. Compression is contraindicated:

(a) after recent abdominal surgery

(b) after renal trauma

(d) when the 5-min film shows already distended calyces indicative of obstruction.

3. 10-min film. AP of the renal areas. There is usually adequate distension of the pelvicalyceal systems with opaque urine by this time. Compression is released when satisfactory demonstration of the pelvicalyceal system has been achieved. If the compression film is inadequate the compression should be checked and repositioned if necessary and a further 50 ml of contrast medium administered and the film after 5 minutes.

4. Release film. Supine AP abdomen taken immediately after release of compression. This film is taken to show the ureters. If this film is satisfactory, the patient is asked to empty their bladder.

5. After micturition film. Full-length supine AP abdomen. The aims of this film are to assess bladder emptying, to demonstrate drainage of the upper tracts, to aid the diagnosis of bladder tumours, to confirm ureterovesical junction calculi and, uncommonly, to demonstrate a urethral diverticulum in females.

Additional images

1. 35° posterior obliques of the kidneys, ureters or bladder – for equivocal collecting system lesions or localization of calculi.

2. Tomography – if renal outlines are not well seen.

3. Prone abdomen following the release film – may improve visualization of distal ureters by making them more dependent.

4. Delayed films at increasing (doubling of time intervals) up to 24 h after injection in renal obstruction.

Variation

Renal colic – a limited study may be performed: preliminary films; 20-min full length (no compression); post-micturition full length; delayed films up to 24 hours as required to show level and cause of obstruction.

Further Reading

Amis, ES. Epitaph for the urogram. Radiology. 1999; 213:639–640.

Becker, JA, Pollack, HM, McClennan, BL. Urography survives. Radiology. 2001; 218:299–300.

Webb, JAW. Imaging in haematuria. Clin Radiol. 1997; 52:167–171.

Ultrasound of the urinary tract

Indications

1. Renal mass lesion

2. Renal parenchymal disease

3. Renal obstruction/loin pain

4. Haematuria

5. Hypertension

6. Renal cystic disease

7. Renal size measurement

8. Bladder outflow obstruction

9. Urinary tract infection

10. Bladder tumour

11. Following renal transplant:

(a) Obstruction

(b) Patency of vessels

12. To guide needle placement in interventional procedures

13. Renal vascular studies.

Contraindications

None.

Patient preparation

Kidneys only – none.

Kidneys and bladder – prehydrate with oral fluids, e.g. 500–1000 ml 1 h before scan, patient attends with a full bladder. This may have the disadvantage of making the collecting systems appear mildly hydronephrotic pre-micturition.

Equipment

3.5–5-MHz transducer.

Technique

1. Patient supine, right (RAO) and left anterior oblique (LAO) positions or lateral for kidneys. The kidneys are scanned longitudinally in an oblique coronal plane supplemented by transverse sections perpendicular to the axis. The right kidney may be scanned through the liver and posteriorly in the right loin. The left kidney is harder to visualize anteriorly, but can be visualized from a lateral approach. In difficult cases the patient should lie on their side with a pillow under the left loin to widen the space between the rib cage and pelvis.

2. The length of the kidney measured by US is 1–2 cm smaller than that measured at excretion urography because there is no geometric magnification. With US measurement, care must be taken to ensure that the true longitudinal lengthwise measurement is obtained. The range of lengths of the normal kidneys is 9–12 cm, and the difference between each kidney should be less than 1–2 cm.

3. The bladder is scanned suprapubically in transverse and longitudinal planes. Measurements taken of the three orthogonal diameters before and after micturition enable an approximate volume to be calculated by multiplying the three diameters and applying a conversion factor. (A conversion factor is usually pre-programmed into modern ultrasound machines.)

4. Renal transplants are usually located in the right or left iliac fossa. These usually lie fairly superficially and are easy to evaluate using oblique planes and gentle pressure to displace overlying bowel loops.

5. The native or transplant kidneys can be evaluated for vascular pathology using Doppler techniques.

• Renal artery stenosis is diagnosed by direct Doppler interrogation of the main renal arteries from a transabdominal approach. Elevated peak systolic velocities greater than 200 cm s^–1 are suggestive of a >50% stenosis. Alternatively, as the main renal arteries in the native kidneys are often hard to visualize, the intrarenal arteries can be evaluated from a flank approach for downstream changes in waveform – the tardusparvus pattern;¹ a slow rise (tardus) to a reduced peak (parvus) producing a prolonged acceleration time (a value >70 ms is indicative of a severe stenosis).

• Renal vein thrombosis is diagnosed by absent colour Doppler venous flow, direct visualization of thrombus within the distended vein, and a raised resistive index with reversal of arterial diastolic flow within the intrarenal arteries.

Reference

1. Kotval, PS. Doppler waveform parvus and tardus: a sign of proximal flow obstruction. J Ultrasound Med. 1989; 8:435–440.

Further Reading

Bih, L-I, Ho, C-C, Tsai, S-J, et al. Bladder shape impact on the accuracy of ultrasonic estimation of bladder volume. Arch Phys Med Rehabil. 1998; 79:1553–1556.

Sidhu, R, Lockhart, ME. Imaging of renovascular disease. Semin Ultrasound, CT and MRI. 2009; 30(4):271–288.

Computed tomography of the urinary tract

Indications

1. Renal colic/renal stone disease

2. Renal tumour

3. Renal/perirenal collection

4. Loin mass

5. Staging and follow-up of renal, collecting system or prostatic cancer (local staging of prostatic cancer is performed using thin-section MRI)

6. Investigation of renal tract obstruction

7. CT angiography may be used to assess renal vessels for suspected renal artery stenosis or arterio-venous fistula or malformation.

Techniques

Standard diagnostic CT

This technique is used to stage and follow-up known renal-tract malignancy or to investigate non-specific signs attributed to the renal tract. Examination of the thorax in addition to the abdomen and pelvis is usually performed where pulmonary metastatic disease or mediastinal nodal spread is a possibility:

1. Venous access is obtained

2. Patient lies supine

3. Scanogram of chest, abdomen and pelvis as appropriate

4. 100 ml i.v. LOCM given

5. Scans obtained approximately 70 s (portal venous phase) after i.v. contrast (arterial phase scans of the liver (20–25 s after i.v. contrast) may be appropriate in those patients with suspected metastatic renal cancer who may have hypervascular liver metastases.)

Renal lesion characterization CT

This is used to assess renal cysts or masses identified on another imaging modality such as ultrasound.

Pre- and post-i.v. contrast scans are obtained through the kidneys in order to assess precontrast attenuation and subsequent enhancement patterns. Many practitioners advise the post-contrast scan be performed at 100 seconds (nephrographic phase) to prevent small intraparenchymal lesions being obscured by corticomedullary differentiation.

Adrenal lesion characterization CT

Indication: adrenal mass is suspected or needs characterization.

Technique: Unenhanced CT of the abdomen to enable measurement of attenuation of any adrenal mass.

A value <10 HU is highly specific for a benign (lipid-rich) adenoma, and is often the only test required. This may, however, be supplemented when necessary by washout CT; re-measurement of the adrenal density in Hounsfield units at 15 min following i.v. contrast. Benign adenomas (whether or not lipid-rich) typically show rapid washout of contrast; an absolute percentage washout (APW) >60% or relative percentage washout (RPW) >40%, on delayed images, is highly specific for a benign lesion.

(Alternatively chemical shift MRI may be used for characterization.)

CT KUB

Plain CT (commonly referred to as CT KUB – kidneys, ureters, bladder) is useful to assess possible stone disease. It is used in many centres as the primary investigation of renal colic (replacing plain KUB radiograph):

1. No intravenous or oral contrast is given.

2. Patient supine. (Some authorities advise prone scanning to differentiate if stones are impacted at the vesicoureteric junction or have passed into the bladder.)

3. A low-radiation-dose technique is used to scan from the top of the kidneys to include the bladder base with a slice thickness of 5 mm or less, as determined by CT scanner. (Due to the low-dose nature of the scan and the absence of i.v. and oral contrast, the scan has a very limited role in identifying pathology other than renal tract calculus disease and should not be used indiscriminately for investigation of non-specific abdominal pain.)

CT urogram (CTU)

This technique uses a combination of unenhanced, nephrographic and delayed scans following i.v. contrast to sequentially allow examination of renal parenchyma and collecting systems.

Suggested protocol:

1. An oral water load of 500–1000 ml 30–60 minutes before injection is recommended to ensure a diuresis and collecting system dilatation. No positive oral contrast

2. Patient supine

3. Initial low-dose unenhanced scans of urinary tract (CT KUB) to determine if renal tract calculus disease is present

4. Low osmolar contrast material (LOCM) 300 mg I ml^–1 100 ml is given as bolus intravenously

5. Thin-section (usually 1 mm) scans are obtained from diaphragm to lower poles of kidneys during nephrographic/parenchymal enhancement phase (100 s following start of bolus injection). Alternatively, scan may instead be acquired during the portal venous phase (70 s) but normal corticomedullary differentiation may make small tumours difficult to appreciate

6. Delayed thin-section (1 mm) scans are acquired from upper pole of kidneys to bladder base 20 min after contrast injection, to examine collecting systems and ureters

7. Source images are reviewed along with multiplanar reconstructions. Post-processing with maximum-intensity projections and surface-shaded displays may be helpful, especially for demonstration.

Variations

The nephrographic phase may be omitted if the scan is specifically for urothelial tumour or collecting system assessment.

Some protocols use diuretics or use abdominal compression bands to achieve collecting system distension.

Radiation dose is a significant consideration for a triple-phase CTU (compared to an IVU) but newer iterative reconstruction techniques increasingly available are reducing the differential. Some authorities advocate the use of a split bolus technique, i.e. 50 ml of i.v. contrast 10–15 min before scanning, with a further 50 ml at the time of the scan, to achieve demonstration of the nephrographic and pyelographic phases with the same acquisition with consequent radiation dose saving.

CT angiography

Indications

1. Renal artery stenosis

2. Renal artery aneurysm, arteriovenous malformation, dissection or thrombosis

3. Delineation of vascular anatomy prior to laparoscopic surgery, e.g. nephrectomy, pyeloplasty.

Technique

1. No oral iodinated contrast used

2. Scan from the upper pole of the kidneys to the aortic bifurcation. Modern scanners are fast enough to produce high-quality studies of the whole abdomen

3. Narrow collimation (1 mm)

4. 100–150 ml i.v. contrast medium (LOCM 300) injected at 3–4 ml s^–1

5. Use of bolus tracking/triggering devices or timing test injections is recommended to ensure appropriate timing. Otherwise scans are initiated after a preset empiric delay of 20–25 s from start of contrast material injection

6. Source axial scans are supplemented by multiplanar reconstructions and maximum intensity projection and volume-rendered surface-shaded display postprocessing.

Further Reading

Adrenal Lesion Characterization CT

Johnson, PT, Horton, KM, Fishman, EK. Adrenal imaging with multidetector CT: evidence-based protocol optimization and interpretive practice. RadioGraphics. 2009; 29:1319–1331.

Technique

Low, G, Dhliwayo, H, Lomas, DJ. Adrenal neoplasms. Clin Radiol. 2012; 67(10):988–1000.

O’Regan, KN, O’Connor, OJ, McLoughlin, P, et al. The role of imaging in the investigation of painless hematuria in adults. Semin Ultrasound, CT and MRI. 2009; 30(4):258–270.

Van Der Molen, AJ, Cowan, NC, Mueller-Lisse, UG, et al. CT urography working group of the European Society of Urogenital Radiology (ESUR). CT urography: definition, indications and techniques. A guideline for clinical practice. Eur Radiol. 2008; 18(1):4–17.

Magnetic resonance imaging of the urinary tract

Indications

1. Local staging of prostatic cancer

2. Local staging of bladder cancer

3. Staging of pelvic lymph nodes

4. Renal mass

5. Screening of patients with von Hippel–Lindau disease or their relatives, or other genetic conditions

6. MR urography where intravenous or CT urography contraindicated

7. MR angiography: potential living related donors, suspected renal artery stenosis.

Technique

Technique will be tailored to the clinical indication. MR of the kidneys and upper abdomen will generally include T1 and T2 weighted sequences in axial and coronal planes with or without fat saturation; with pre and post contrast T1 weighted imaging at 30 and 70 seconds. MRI of the abdomen and pelvis can be obtained to assess retroperitoneal lymphadenopathy as part of the staging investigations for patients with bladder and prostate cancer but CT is often used for this purpose with MRI reserved for local staging.

Magnetic resonance imaging of the prostate

Technique/example protocol

1. Patient supine. Phased array body coil. The best images will be obtained with an endorectal coil, but many authorities do not use these. 1.5T or 3T scanners are both used. 3T scanners afford better signal-to-noise ratio but may be subject to more artefacts, notably susceptibility

2. Antiperistaltic drugs (hyoscine butyl-bromide or glucagon are recommended)

3. T1W and T2W axial scans whole pelvis

4. Thin-section (3–4 mm) small field of view T1-weighted spin echo (SE) scans in axial plane orthogonal to the axis of the prostate to evaluate for post-biopsy haemorrhage

5. Thin-section (3–4 mm) small field of view T2-weighted spin echo (SE) scans in transverse, sagittal and coronal planes orthogonal to the axis of the prostate

6. Multiparametric MRI – there is increasing use of the following functional studies:

(a) Diffusion weighted imaging values 0, 100 and 800–1400 s/mm² with apparent diffusion coefficient (ADC) map

(b) Dynamic contrast-enhanced (DCE) T1W imaging

Further Reading

Barentsz, JO, Richenberg, J, Clements, R, et al. ESUR prostate MR guidelines. Eur Radiol. 2012; 22(4):746–757.

Magnetic resonance urography

Indications

1. To demonstrate the collecting system/determine level of obstruction in a poorly functioning/obstructed kidney

2. Urinary tract obstruction unrelated to urolithiasis. Suspected renal colic from underlying calculus is better imaged with CT KUB

3. Congenital anomalies

4. Renal transplant donor assessment (combined with MR angiography).

Technique

The two most common MR urographic techniques are:

• static fluid-sensitive urography using heavily T2-weighted MRI techniques to visualize fluid-filled structures (equivalent to magnetic resonance cholangio-pancreatography (MRCP))

• excretory MR urography using T1-weighted sequences post gadolinium enhancement.

1. Patient supine with an empty bladder for comfort. If the bladder is of interest, a moderately full bladder may be preferred.

2. Scout views are obtained.

3. Static MR urography may be performed prior to excretory urography. Thick-slab, single-shot, fast-spin echo or a similar thin-section technique, e.g. half-Fourier rapid acquisition with relaxation enhancement; single-shot, fast-spin echo; single-shot, turbo-spin echo. 3D respiratory triggered sequences may be used to obtain thin-section data sets that may be further post-processed.

4. Oral or intravenous hydration, compression or diuretics may be used to enhance collecting system distension.

5. Excretory MR urography: a gadolinium-based contrast agent is administered i.v. using a dose of 0.1 mmol gadolinium kg^–1 body weight. The collecting systems are imaged during the excretory phase (10–20 min) using a breath-hold, three-dimensional gradient echo, T1-weighted sequence. Fat suppression will improve the conspicuity of the ureters. T2* effects from a high concentration of contrast agent may reduce the signal intensity of urine and potentially obscure small masses within the collecting system. This can be overcome by using a lower volume of i.v. contrast but may compromise soft-tissue imaging.

Further Reading

Leyendecker, JR, Barnes, CE, Zagoria, RJ. MR urography: techniques and clinical applications. RadioGraphics. 2008; 28(1):23–46.

Nikken, JJ, Krestin, GP. MRI of the kidney – state of the art. Eur Radiol. 2007; 17(11):2780–2793.

Magnetic resonance imaging of the adrenals

Indications

Characterization of adrenal mass.

Technique

Chemical shift imaging: based on a high proportion of intracellular lipid causing alteration of the local magnetic environment within the voxel and hence resonant frequency of protons. Lipid-rich benign adenomas can be shown to lose signal on opposed phase T1W imaging compared to in-phase studies. This is highly specific.

Alternative: unenhanced CT can be used to characterize an adrenal mass as malignant (see above) or FDG-PET can be used to characterize an adrenal mass as malignant (see Chapter 11).

Further Reading

Low, G, Dhliwayo, H, Lomas, DJ. Adrenal neoplasms. Clin Radiol. 2012; 67(10):988–1000.

Magnetic resonance renal angiography

Indications

1. Possible renal artery stenosis

2. Number and disposition of renal arteries

(a) Pre surgery

(b) Renal transplant donors.

Technique

1. Three-dimensional spoiled gradient echo sequences before and following i.v. injection (2 ml s^–1) of 0.1 mmol kg^–1 gadolinium.

2. A saline flush (20 ml) at the same rate is given.

3. Accurate timing of injection is determined by bolus tracking with ROI (region of interest) positioned over abdominal aorta.

4. The scan is triggered when signal intensity at the ROI reaches a preset value.

5. Source imaging is supplemented by post processing with multiplanar reconstructions and maximum-intensity projections.

Alternative non-contrast MR angiographic techniques

Time-of-flight and phase contrast angiography are of limited application in this context in comparison to contrast-enhanced studies.

Further Reading

Soulez, G, Pasowicz, M, Benea, G, et al. Renal artery stenosis evaluation: diagnostic performance of gadobenate dimeglumine-enhanced MR angiography – comparison with DSA. Radiology. 2008; 247(1):273–285.

Micturating cystourethrography

Indications

1. Vesicoureteric reflux

2. Study of the urethra during micturition

3. Bladder leak post surgery or trauma

4. Urodynamic studies, e.g. for incontinence.

Contraindications

Acute urinary tract infection.

Contrast medium

High osmolar contrast material (HOCM) or LOCM 150 mg I ml^–1.

Equipment

1. Fluoroscopy unit with spot film device and tilting table

2. Video recorder (for urodynamics)

3. Bladder catheter.

Patient preparation

The patient empties their bladder prior to the examination.

Preliminary image

Coned view of the bladder.

Technique

To demonstrate vesico-ureteric reflux (this indication is almost exclusively confined to children):

1. Using aseptic technique the bladder is catheterized. Residual urine is drained.

2. Contrast medium (LOCM 150 mg I ml^–1) is slowly injected or dripped in with the patient supine and bladder filling is observed by intermittent fluoroscopy. It is important that early filling is monitored by fluoroscopy in case the catheter is malpositioned, e.g. in the distal ureter or vagina.

3. Intermittent monitoring is also necessary to identify transient reflux. Any reflux should be recorded.

4. The catheter should not be removed until the radiologist is confident that the patient will be able to micturate, the patient does not tolerate further infusion or until no more contrast medium will drip into the bladder.

5. Older children and adults are given a urine receiver but smaller children should be allowed to pass urine onto absorbent pads on which they can lie. Children can lie on the table but adults will probably find it easier to micturate while standing erect. In infants and children with a neuropathic bladder, micturition may be accomplished by suprapubic pressure.

6. Spot images are taken during micturition and any reflux recorded. A video recording may be useful. The lower ureter is best seen in the anterior oblique position of that side. Boys should micturate in an oblique or lateral projection, so that spot films can be taken of the entire urethra.

7. Finally, a full-length view of the abdomen is taken to demonstrate any undetected reflux of contrast medium that might have occurred into the kidneys and to record the post-micturition residue.

8. Lateral views are helpful when fistulation into the rectum or vagina are suspected.

9. Oblique views are needed when evaluating for leaks.

10. Stress views are used for urodynamic studies.

Aftercare

1. No special aftercare is necessary, but patients and parents of children should be warned that dysuria, possibly leading to retention of urine, may rarely be experienced. In such cases a simple analgesic is helpful and children may be helped by allowing them to micturate in a warm bath.

2. Most children will already be receiving antibiotics for their recent urinary tract infection – the dose will usually be doubled for 3 days, starting on the day prior to the procedure. Children not already on antibiotics will also usually be prescribed a 3-day course (often trimethoprim).

Complications

1. Urinary tract infection

2. Catheter trauma may lead to dysuria, frequency, haematuria and urinary retention

3. Complications of bladder filling, e.g. perforation from overdistension – prevented by using a non-retaining catheter, e.g. Jacques

4. Catheterization of vagina or an ectopic ureteral orifice

5. Retention of a Foley catheter.

Ascending urethrography in the male

Indications

1. Stricture

2. Urethral trauma

3. Fistulae or false passage

4. Congenital abnormalities.

Contraindications

1. Acute urinary tract infection

2. Recent instrumentation.

Contrast medium

LOCM 200–300 mg I ml^–1 20 ml. Pre-warming the contrast medium will help reduce the incidence of spasm of the external sphincter.

Equipment

1. Fluoroscopy unit and spot film device

2. Foley catheter 8-F.

Patient preparation

Consent.

Preliminary image

Coned supine postero-anterior (PA) of bladder base and urethra.

Technique

1. Patient supine

2. The catheter is connected to a 50 ml syringe containing contrast medium and flushed to eliminate air bubbles

3. Using aseptic technique the tip of the catheter is inserted so that the balloon lies in the fossa navicularis (i.e. immediately proximal to the meatus within the glans) and its balloon is inflated with 2–3 ml of water to anchor the catheter and occlude the meatus

4. Contrast medium is injected under fluoroscopic control and steep (30–45°) oblique films taken. Gentle traction on the catheter is used to straighten the penis over the ipsilateral leg and prevent urethral overlap or foreshortening from obscuring pathology.

Depending on the clinical indication, ascending urethrography may be followed by descending micturating cystourethrography to demonstrate the proximal urethra and bladder, assuming there is no contraindication to bladder catheterization, e.g. false passage, stricture. It may be possible to fill the bladder retrogradely via the urethral catheter if the patient is able to relax the bladder neck (and thus avoid bladder catheterization).

Aftercare

None.

Complications due to the technique

1. Acute urinary tract infection

2. Urethral trauma

3. Intravasation of contrast medium, especially if excessive pressure is used to overcome a stricture.

Further Reading

Kawashima, A, Sandler, CM, Wasserman, NF, et al. Imaging of urethral disease: a pictorial review. RadioGraphics. 2004; 24:S195–S216.

Retrograde pyeloureterography

Indications

1. Demonstration of the site and nature of an obstructive lesion

2. Demonstration of the pelvicalyceal system and potential urothelial abnormalities after previous indeterminate imaging.

Contraindications

Acute urinary tract infection.

Contrast medium

HOCM or LOCM 150–200 mg I ml^–1 (i.e. not too dense to obscure small lesions) 10 ml.

Equipment

Fluoroscopy unit.

Patient preparation

As for surgery.

Preliminary image

Full-length supine antero-posterior (AP) abdomen when the examination is performed in the X-ray department.

Technique

In the operating theatre

The surgeon catheterizes the ureter via a cystoscope and advances the ureteric catheter to the desired level. Contrast medium is injected under fluoroscopic control and spot films are exposed. Technique and imaging as below. Some form of hard copy or soft copy recording is recommended – ideally to the hospital PACS system.

In the X-ray department

1. With ureteric catheter(s) in situ, the patient is transferred from the operating theatre to the X-ray department.

2. Urine is aspirated and, under fluoroscopic control, contrast medium is slowly injected. Care should be taken to eliminate air bubbles before injection (as these may mimic pathology such as tumour or calculus. About 3–5 ml is usually enough to fill the pelvis but if the patient complains of pain or fullness in the loin, the injection should be terminated before this.

3. Images are taken as the catheter is withdrawn. These should include frontal and oblique projections.

Aftercare

1. Post-anaesthetic observations

2. Prophylactic antibiotics may be used.

Complications

1. Pyelosinus extravasation and pyelotubular reflux due to over-filling may result in pain, fever and rigors

2. Introduction of infection

3. Damage or perforation of the ureters or renal pelvis.

Conduitogram

Indications

1. To evaluate for development of upper tract tumour

2. Suspected stricture at anastomosis of ureter and ileal urinary conduit

3. Suspected narrowing of conduit.

Contrast

LOCM or HOCM 150 mg I ml^–1.

Technique

1. The patient should be advised to bring a spare stoma bag or one should be available.

2. A urinary catheter is chosen tailored to the size of the stoma. (Although larger catheters may pass more easily, a smaller catheter may be needed.)

3. The catheter is flushed with contrast medium and a syringe or giving set with contrast medium is connected. It is very important to exclude air bubbles which can be confused for upper tract tumours.

4. The conduit is then catheterized using a sterile technique.

5. The catheter balloon is inflated and minimal traction applied to the catheter to occlude the stoma.

6. Contrast is instilled under fluoroscopic control into the lumen of the conduit.

7. AP and oblique views are taken as appropriate, of sufficient number to demonstrate the whole pelvicalyceal systems and ureters.

Percutaneous renal cyst puncture and biopsy

Indications

1. Diagnostic biopsy: unexplained renal failure, mass, etc.

2. Renal cyst puncture to relieve local symptoms attributable to a cyst.

Contraindications

1. Bleeding diathesis

2. The possibility of renal hydatid disease.

Equipment

Ultrasound or CT guidance.

Patient preparation

Pre-medication or sedation may be needed.

Technique

Insertion of the needle can be controlled by either ultrasonography or CT:

1. The patient is placed in the prone position, or as appropriate depending on patient habitus and position of lesion.

2. The kidney, mass or cyst is located directly with US or CT or indirectly, after opacification of the kidneys with i.v. contrast medium. The optimum site for puncture is marked on the skin. For renal biopsy in the investigation of parenchyma disease the lower pole of the left kidney is often preferred.

3. The skin and subcutaneous tissues are infiltrated with 1% lidocaine.

4. The needle is passed directly into the lesion during suspended respiration. US or CT are used to monitor the path of the needle. For cyst puncture the stilette is removed and the cyst contents are aspirated and examined.

5. For biopsy, the biopsy needle is deployed following confirmation of needle position with imaging.

Complications

• Bleeding – perinephric or haematuria

• Arteriovenous fistula

• Pseudoaneurysm.

Percutaneous antegrade pyelography and nephrostomy

This is the introduction of a drainage catheter into the collecting system of the kidney.

Indications

1. Renal tract obstruction

2. Pyonephrosis

3. Prior to percutaneous nephrolithotomy

4. Ureteric or bladder fistulae: external drainage, i.e. urinary diversion may allow closure.

Contraindications

Uncontrolled bleeding diathesis.

Contrast medium

As for percutaneous renal puncture.

Equipment

1. Puncturing needle: coaxial needle/catheter set or sheathed 18G needle

2. Drainage catheter: at least 6-F pigtail with multiple side holes

3. Guidewires: conventional J-wire ± extra stiff wire

4. US and/or fluoroscopy – usually used in combination.

Patient preparation

1. Fasting for 4 h

2. Premedication as required

3. Prophylactic antibiotic.

Technique

Patient position

Patient lies prone oblique with a foam pad or pillow under the abdomen to present the kidney optimally.

Identifying the collecting system prior to the definitive procedure

1. Freehand or with a biopsy needle attachment; US guidance is the most common method for localizing the kidney and guiding the initial needle puncture into the collecting system.

2. Excretion urography, if adequate residual function and a non-dilated system using a parallax technique.

3. Occasionally retrograde injection through an ileal conduit or a ureteric catheter may be used to demonstrate the target collecting system.

Site/plane of puncture

A point on the posterior axillary line is chosen below the twelfth rib. Having identified the mid/lower pole calyces with US or contrast, the plane of puncture is determined. This will be via the soft tissues and renal parenchyma avoiding direct puncture of the renal pelvis, so that vessels around the renal pelvis will be avoided and the drainage catheter will gain some purchase on the renal parenchyma. There is a relatively avascular plane between the ventral and dorsal parts of the kidney which affords the ideal access.

Techniques of puncture, catheterization

The skin and soft tissues are infiltrated with local anaesthetic using a spinal needle.

Puncture may then be made using one of the following systems (depending on preference):

1. An 18G sheathed needle, or Kellett needle, using the Seldinger technique for catheterization. Contrast injection is used to confirm successful siting of the needle and for preliminary demonstration of the pelvicalyceal system. On occasion air is used as a negative contrast medium to enable targeting of a posterior non-dependent calyx. Upon successful puncture a J-guidewire is inserted and coiled within the collecting system; the sheath is then pushed over the wire, which may be exchanged for a stiffer wire. Dilatation is then performed to the size of the drainage catheter, which is then inserted. Care must be taken not to kink the guidewire within the soft tissues. Sufficient guidewire should be maintained within the collecting system, ideally with the wire in the upper ureter to maintain position and, if kinking does occur, the kinked portion of the wire can be withdrawn outside the skin.

2. Coaxial needle puncture systems using a 22/21G puncturing needle that takes a 0.018 guidewire. This affords a single puncture with a fine needle, with insertion of a three-part coaxial system to allow insertion of 0.035 guidewire and then proceed as in (1) above.

3. The trocar-cannula system, in which direct puncture of the collecting system is made with the drainage catheter already assembled over a trocar. On removal of the trocar the drainage catheter is advanced further into the collecting system.

Having successfully introduced the catheter, it is securely fixed to the skin and drainage commenced.

Antegrade pyelography is rarely performed as an isolated procedure; usually it is undertaken following placement of, and via, a nephrostomy catheter as above. Oblique and AP images are taken with gentle introduction of water-soluble contrast medium. Semi-erect films may be necessary to encourage contrast medium down the ureters to show the site and nature of obstruction. Post nephrostomy studies are best performed after a delay of 1–2 days to allow the patient to recover and be able to cooperate, blood clot to resolve, and infected systems to be drained.

Aftercare

1. Bed rest for 4 h

2. Pulse, blood pressure and temperature half-hourly for 6 h

3. Analgesia

4. Urine samples sent for culture and sensitivity.

Complications

1. Septicaemia

2. Haemorrhage

3. Perforation of the collecting system with urine leak

4. Unsuccessful drainage

5. Injury to adjacent organs such as lung, pleura, spleen or colon

6. Later catheter dislodgement.

Further Reading

Dyer, RB, Regan, JD, Kavanagh, PV, et al. Percutaneous nephrostomy with extensions of the technique: step by step. RadioGraphics. 2002; 22:503–525.

Percutaneous nephrolithotomy

This is the removal of renal calculi through a nephrostomy track. It is often reserved for large complicated calculi which are unsuitable for extracorporeal shock-wave lithotripsy.

Indications

1. Removal of renal calculi

2. Disintegration of large renal calculi.

Contraindications

Uncontrolled bleeding diathesis.

Contrast medium

As for percutaneous renal puncture.

Equipment

1. Puncturing needle (18G): Kellett (15–20 cm length) or equivalent

2. Guidewires, including hydrophilic and superstiff

3. Track dilating equipment; Teflon dilators (from 7-F–30-F), metal coaxial dilators or a special angioplasty-type balloon catheter

4. US machine

5. Fluoroscopy facilities with rotating C arm if possible.

Patient preparation

1. Full discussion between radiologist/urologist concerning indications, etc.

2. Imaging (IVU, CT KUB, CTU) to demonstrate position of calculus and relationship to calyces

3. General anaesthetic

4. Coagulation screen

5. Two units of blood cross matched

6. Antibiotic cover

7. Premedication

8. Bladder catheterization, as large volumes of irrigation fluid will pass down the ureter during a prolonged procedure.

Technique

Pre-procedure planning may include a CT KUB and CTU to localize stones and to choose most appropriate access.

Patient position

As for a percutaneous nephrostomy, usually prone (see p. 147).

Methods of opacification of the collecting system

1. Retrograde ureteric catheterization for demonstration and distension of the collecting system may be achieved. In addition, a retrograde occlusion balloon catheter in the ureter will prevent large fragments of stone passing down the ureter

2. Intravenous excretion urography

3. Antegrade pyelography; this also enables distension of the collecting system.

Puncture of the collecting system

A lower pole posterior calyx is ideally chosen if the calculus is situated in the renal pelvis. Otherwise the calyx in which the calculus is situated is usually punctured. Special care must be taken if puncturing above the twelfth rib because of the risk of perforating the diaphragm and pleura. Puncture is in an oblique plane from the posterior axillary line through the renal parenchyma. Puncture of the selected calyx is made using a combination of US and a rotating C-arm fluoroscopic facility. On successful puncture a guidewire is inserted through the cannula and as much wire as possible is guided into the collecting system. The cannula is then exchanged for an angled catheter and the wire and catheter are manipulated into the distal ureter. At this stage full dilatation may be performed (single-stage) or a nephrostomy tube left in situ with dilatation later (two-stage procedure).

Dilatation

This is carried out under general anaesthesia. It is performed using Teflon dilators from 7-F to 30-F, which are introduced over the guidewire. Alternatively, metal coaxial dilators or a special angioplasty balloon (10 cm long) are used. A sheath is inserted over the largest dilator or balloon through which the nephroscope is passed followed by removal of the calculus or disintegration.

Removal/disintegration

Removal of calculi of less than 1 cm is possible using a nephroscope and forceps. Larger calculi must be disintegrated using an ultrasonic or electrohydraulic disintegrator.

Aftercare

1. A large bore soft non-locking straight nephrostomy tube (sutured) is left in for 24 hours following the procedure.

2. Patient care is usually determined by the anaesthetist/urologist.

3. Plain radiograph of renal area to ensure that all calculi/fragments have been removed.

Complications

Immediate

1. Failure of access, dilatation or removal

2. Perforation of the renal pelvis on dilatation

3. Inadvertent access to renal vein and IVC

4. Haemorrhage. Less than 3% of procedures should require transfusion. Rarely, balloon tamponade of the tract or embolization may be required

5. Damage to surrounding structures, i.e. diaphragm, colon, spleen, liver and lung

Delayed

1. Pseudo-aneurysm of an intrarenal artery

2. Arterio-venous fistula.

Renal arteriography

Indications

1. Renal artery stenosis prior to angioplasty or stent placement. Diagnostic arteriography has been replaced generally by MR or CT angiography (MRA or CTA).

2. Assessment of living related renal transplant donors – replaced generally by MRA or CTA.

3. Embolization of vascular renal tumour prior to surgery.

4. Haematuria particularly following trauma, including biopsy. This may precede embolization.

5. Prior to prophylactic embolization of an angiomyolipoma (AML) or therapeutic embolization of a bleeding AML.

Contrast medium

Flush aortic

LOCM 300/320 mg I ml^–1, 45 ml at 15 ml s^–1.

Selective renal artery injection

LOCM 300 mg I ml^–1, 10 ml at 5 ml s^–1, or by hand injection.

Equipment

1. Digital fluoroscopy unit

2. Pump injector

3. Catheters:

(a) Flush aortic injection – pigtail 4-F

(b) Selective injection – Sidewinder or Cobra catheter.

Technique

1. Femoral artery puncture

2. Flush aortography.

The catheter is placed proximal to the renal vessels (i.e. approximately T12) and AP and oblique runs are performed (the oblique run demonstrating the renal origins). Selective catheterization as required is used for optimal demonstration of intrarenal vessels, and prior to interventional procedures.

Static renal radionuclide scintigraphy