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THE RENAL TRACT 189 vascular rejection or acute tubular necrosis can be present under such circumstances. 34 Vascular complications can include arterial stenosis or thrombosis, venous stenosis or thrombosis, pseudoaneurysms and arteriovenous fistulae. 33 Renal artery stenosis This generally occurs at the site of the anastomosis close to the iliac artery but can also occur along the length of the artery or even affect the intrarenal branches. The patient may present with severe, difficult-to-control hypertension, graft dysfunction, or both. Alternatively the patient’s renal function may deteriorate following angiotensin-converting enzyme inhibitor therapy and this is also an indication of a possible underlying RAS. Careful Doppler examination is now the accepted first-line investigation in the diagnosis of RAS. In most cases it is possible to trace the artery back to its anastomosis with the iliac artery, using colour Doppler. If the site of the stenosis is identified, spectral Doppler will demonstrate an increase in peak systolic velocity at the lesion, followed by poststenotic turbulence (Fig. 7.28, B,C). This can be difficult to pinpoint with MRA, especially if bowel is overlying the vessel. A delayed systolic rise (the parvus tardus waveform) can be identified in the intrarenal spectral Doppler waveforms, as for the native kidney (see above). The diagnosis however is primarily made on the peak systolic velocity within the renal artery. A value of < 2.5 m/s is normal while > 2.5 m/s constitutes RAS. If the stenosis is severe, it may be difficult to identify colour flow in the kidney and the waveform may be reduced in velocity with a tiny, damped trace in the main vessel. A stenosis affecting an interlobar artery may result in focal, segmental changes in the kidney. In general, contrast angiography is only used to grade and treat stenoses after a positive ultrasound scan, or when a high index of clinical suspicion persists, despite a negative ultrasound. 33 Renal vein thrombosis The occlusion may be partial or complete and the venous Doppler spectrum may therefore be absent (Fig. 7.29). If venous thrombosis is partial, the arterial spectral waveform becomes very pulsatile, with reverse end diastolic flow; in the clinical setting of an oliguric patient with a tender graft in the early postoperative period, this is almost pathognomonic for RVT. During the early stages, when thrombosis is incomplete, venous flow may be seen in the kidney, but the artery is of reduced velocity. 25 The ultrasound findings of renal vein thrombosis may be indistinguishable from severe rejection; however venous flow is generally unaffected in the latter. Thrombosis is rare, occurring typically in the immediate postoperative period. 33 It may be associated with a faulty venous anastomosis, secondary to compression of the vein, for example by a large, perivenous collection, or the patient may have an increased thrombotic tendency for a number of reasons. Pseudoaneurysms and arteriovenous fistulae These may sometimes form as a result of vascular damage during biopsy procedures. They are usually not significant and tend to resolve spontaneously (Fig. 7.30A). An arteriovenous fistula shows an irregular knot of vessels on colour or power Doppler with a pulsatile venous waveform and high peak and end diastolic velocity in the feeding artery. A large draining vein may also be seen. A pseudoaneurysm may appear cystic on the grey-scale image, but will demonstrate filling on colour Doppler with a pulsatile flow velocity waveform (Fig. 7.30B, C). Careful biopsy technique helps to avoid such lesions (see Chapter 11). Infection This is characterized by swelling of the uroepithelium, especially with fungal infections. Fungal balls may be visible as relatively hyperechoic structures within the PCS (Fig. 7.31). Acute tubular necrosis This may demonstrate prominent medullary pyramids on ultrasound, with low end diastolic flow. Reverse end diastolic flow is uncommon but recognized. A biopsy is required for confirmation.
190 ABDOMINAL ULTRASOUND A + 8.7MM B Figure 7.29 Renal vein thrombosis. (A) Poor transplant perfusion, with scanty demonstration of arterial flow. (B) The same vessels demonstrate reversal of flow at the end of the cardiac cycle. (C) The bidirectional flow is demonstrated on the spectral trace. NORMAL 2623 C
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Abdominal Ultrasound
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Abdominal Ultrasound How, Why and W
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v Contents Contributors Preface ix
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vii Contributors Rosemary Arthur FR
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ix Preface Ultrasound continues to
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ABBREVIATIONS xi MHA MHV MI MPV MRA
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Chapter 1 1 Optimizing the diagnost
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OPTIMIZING THE DIAGNOSTIC INFORMATI
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Chapter 2 17 The normal hepatobilia
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THE NORMAL HEPATOBILIARY SYSTEM 19
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Chapter 3 41 Pathology of the gallb
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PATHOLOGY OF THE GALLBLADDER AND BI
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Chapter 4 79 Pathology of the liver
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PATHOLOGY OF THE LIVER AND PORTAL V
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Chapter 5 121 The pancreas CHAPTER
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THE PANCREAS 123 the patient’s le
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THE PANCREAS 125 Acute pancreatitis
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THE PANCREAS 127 E F G Figure 5.3 c
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A C DISTANCE = 3.43 CM 5%. 13 Over
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THE PANCREAS 131 G H I Figure 5.5 c
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THE PANCREAS 133 head of pancreas.
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THE PANCREAS 135 pancreatic juice i
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Chapter 6 137 The spleen and lympha
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Page 166 and 167: Chapter 7 153 The renal tract CHAPT
Page 168 and 169: THE RENAL TRACT 155 As with any oth
Page 170 and 171: THE RENAL TRACT 157 A B q 0 LRA AO
Page 172 and 173: THE RENAL TRACT 159 junctions of or
Page 174 and 175: THE RENAL TRACT 161 A B Figure 7.5
Page 176 and 177: THE RENAL TRACT 163 carcinomas, the
Page 178 and 179: THE RENAL TRACT 165 the vesicourete
Page 180 and 181: THE RENAL TRACT 167 Table 7.1 Sourc
Page 182 and 183: THE RENAL TRACT 169 A B Figure 7.13
Page 184 and 185: THE RENAL TRACT 171 Table 7.2 Diffe
Page 186 and 187: THE RENAL TRACT 173 Ultrasound stil
Page 188 and 189: THE RENAL TRACT 175 CT is useful fo
Page 190 and 191: THE RENAL TRACT 177 Xanthogranuloma
Page 192 and 193: THE RENAL TRACT 179 As with acute t
Page 194 and 195: THE RENAL TRACT 181 der with increa
Page 196 and 197: THE RENAL TRACT 183 ● ● Morphol
Page 198 and 199: THE RENAL TRACT 185 ● ● hydrone
Page 200 and 201: THE RENAL TRACT 187 A Figure 7.27 A
Page 204 and 205: THE RENAL TRACT 191 B A C Figure 7.
Page 206 and 207: THE RENAL TRACT 193 computerised ul
Page 208 and 209: Chapter 8 195 The retroperitoneum a
Page 210 and 211: THE RETROPERITONEUM AND GASTROINTES
Page 228 and 229: Chapter 9 215 The paediatric abdome
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Page 232 and 233: THE PAEDIATRIC ABDOMEN 219 B A B Fi
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Page 244 and 245: THE PAEDIATRIC ABDOMEN 231 A LT B C
Page 250 and 251: THE PAEDIATRIC ABDOMEN 237 mesenter
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THE PAEDIATRIC ABDOMEN 239 E F G Fi
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THE PAEDIATRIC ABDOMEN 241 system i
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Chapter 10 The acute abdomen 243 CH
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THE ACUTE ABDOMEN 245 scan of the p
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THE ACUTE ABDOMEN 247 LIVER LS GB S
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THE ACUTE ABDOMEN 249 D A RT B C E
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THE ACUTE ABDOMEN 251 17. Patlas M,
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Chapter 11 253 Interventional and o
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INTERVENTIONAL AND OTHER TECHNIQUES
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275 Bibliography and further readin
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277 Index A Abdomen, acute gastroin
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INDEX 279 Continuous ambulatory per
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INDEX 281 Intravenous urography (IV
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INDEX 283 Phrygian cap, 29 Pneumobi
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