Critical Review of Diagnostic Methods Used in Chronic Pancreatic Disease

This paper provides a balanced assessment of the various pancreatic function tests and imaging techniques used in the differential diagnosis of chronic pancreatic disease. Function tests that study the digestive capacity of the pancreas (fat absorption of dietary lipids, fluorescein- or radiolabelled fats, bentiromide test, etc) have high specificity, but very low sensitivity. This is because 90% of pancreas has to be destroyed before steatorrhea or creatorrhea occurs. Tests that directly measure pancreatic bicarbonate and protein secretion (secretin test, etc) are more accurate and may detect pancreatic dysfunction even before anatomical changes occur. Measurement of pancreatic enzymes in serum or urine, or the decreased decline of serum amino acids during their incorporation into pancreatic enzymes, are not sufficiently sensitive or specific to help diagnose pancreatic disease. Sensitive and specific tumour markers are not yet available. Thus screening tests are not cost-effective - if they are negative, they do not exclude pancreatic disease; and if positive, they have to be confirmed by more specific tests. Imaging techniques are the most commonly used methods of investigation. The usefulness of abdominal survey films, barium studies, percutaneous transhepatic cholangiography, endoscopic retrograde cholangiopancreatography (ERCP), ultrasonography, computed tomographic scan, magnetic resonance imaging and endoscopic ultrasonography is critically reviewed. Most of the radiological methods can be combined with cytology or biopsy. Histology demonstrating malignancy establishes this diagnosis, but negative biopsies do not exclude malignant tumours. Presently only ERCP and endoscopic ultrasound can diagnose cancers sufficiently early to allow for possible `curative' surgery, and only endoscopic ultrasound is capable to stage tumours for the assessment of resectability