CYSTIC FIBROSIS DIAGNOSIS

Cystic fibrosis (CF) is a common, autosomal recessive multisystem disease. The main organs affected are the lungs, liver and pancreas. Accumulation of mucus in the bronchi rapidly leads to respiratory problems including infections, with a predisposition to abscess formation with destruction of the terminal bronchioles developing into bronchiectasis.

Pancreatic insufficiency, requiring enzyme supplements, is a feature of CF, with gradual fatty replacement and subsequent fibrosis of pancreatic tissue, resulting in increased echogenicity of the pancreatic parenchyma.

The pancreas is generally reduced in size. Cysts, calcification and ductal dilatation may also be found. Advances in the management of pulmonary problems associated with CF have led to longer survival and a subsequent increase in the prevalence of chronic liver disease.

Annual ultrasound examination is recommended as sonographic changes may be identified in the absence of abnormality on biochemical assessment. The liver may be hyperechoic and the texture becomes coarse and nodular as fibrosis develops. Increased periportal echogenicity may be demonstrated. Eventually cirrhosis develops, causing portal hypertension. Assessment of the portal venous system with colour and spectral Doppler is useful, providing a baseline with which to compare progression of the disease.

The gallbladder is small in up to one-third of patients. This microgallbladder measures less than 3 × 1 × 1 cm after fasting and is filled with mucus. Up to 10% of patients with CF may have gallstones; cholecystitis and biliary strictures may occur.