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ABDOMINAL ULTRASOUND
abscess can be treated successfully using these techniques
combined with appropriate antibiotic
therapy.
THE ACUTE PANCREAS
(See also Chapter 5.) Most cases of acute pancreatitis
are suspected clinically, with raised amylase levels
and often a history of recurrent epigastric pain
pointing to the diagnosis of acute pancreatitis (Fig.
10.4). Although pancreatitis may be due to
abdominal trauma, it is more frequently due to
gallstone obstruction or alcohol abuse. The pancreas
often appears normal even when acutely
inflamed, so ultrasound examination should focus
on the possible causes (such as gallstones, biliary
dilatation or evidence of alcoholic liver disease) and
complications (pseudocysts, portal or splenic vein
thrombosis). Many pancreatic pseudocysts are now
managed successfully by endoscopic ultrasoundguided
transgastric drainage. 13
RENAL TRACT EMERGENCIES
(See also Chapter 7.) Ultrasound is usually the firstline
investigation in the assessment of acute loin
pain, which in the absence of trauma is commonly
due to acute urinary tract obstruction and/or renal
infection (Fig. 10.5). Less common acute presentations
include renal vein thrombosis or spontaneous
haemorrhage, usually from a renal tumour
or cyst.
Until recently, ultrasound and/or intravenous
urography (IVU) have been the investigations of
choice in acute renal colic due to suspected ureteric
calculus, and in most UK centres the IVU is currently
the method of choice for demonstrating
ureteric obstruction (Fig. 10.5E). Low-dose
unenhanced multislice CT is increasingly being
recommended as a replacement for these two
modalities, 14 but even with this technique diagnostic
pitfalls exist. 15 Abdominal ultrasound with or
without plain radiography may still provide comparable
accuracy where CT resources are limited.
16,17
The main limitation of ultrasound in acute
ureteric obstruction is that obstruction may be
present in the early stages without collecting system
dilatation. But the minimally dilated renal
pelvis, which would normally be dismissed as unremarkable
in a patient with a full bladder, should
raise the operator’s suspicion in the patient with
acute loin pain. Doppler ultrasound of the kidneys
shows a higher resistance index in the obstructed
kidney than in the normal side. 18 Upper tract
obstruction can be relieved via cystoscopy-guided
ureteric stent placement. Ultrasound-guided percutaneous
nephrostomy may be required if this is
not practicable, or if there is evidence of infection.
Renal infection with parenchymal involvement
(acute pyelonephritis) may be the cause of severe
acute loin pain with fever, but ultrasound examination
mostly shows no abnormality. Occasionally
the skilled operator using high-specification equipment
may be able to identify segmental areas of
high reflectivity, showing decreased blood flow
with power Doppler. The diagnosis of this condition
is usually based on clinical criteria, but
these segments can be demonstrated with CT if
necessary.
Figure 10.4 Pancreatitis with a large pseudocyst. The
patient was acutely tender, and the cyst was drained
under ultrasound guidance.
OTHER RETROPERITONEAL EMERGENCIES
(See also Chapter 8.) Ultrasound has an established
role in identifying the presence of an abdominal
aortic aneurysm, but should not be used to assess
subacute leakage or rupture. However, where rupture
is suspected, and no previous imaging results