cbd in usg report

December 15, 2021 By admin Off

The common bile duct (CBD) was measured in 600 ultrasound studies. In normal patients the mean width of the CBD increased from 2.8 mm in the age group 20 years or younger to 4.1 mm in patients 71 years of age or older. The mean width of the CBD for all age groups in normal cases was 3.4 (range 2 to 11 mm). In presence of cholelithiasis the mean width of the CBD was 4.5 mm (range 2 to 15 mm). There was no further increase of the CBD after cholecystectomy (mean width 4.6 mm, range 2 to 12 mm). The CBD in patients with hepatocellular disease was wider than normals (mean 4.4 mm) and markedly increased in patients with pancreatic disease (mean 6.2 mm, range 2 to 21 mm) due to obstruction in several cases.

Her pancreas was seen to be swollen. The enlargement of the pancreas may have various causes and if a biliary stone is lodged in the distal CBD then the patient may develop pancreatitis. With aging, the pancreas becomes more echogenic and atrophic on ultrasound.

The relationship to ‘pathology’ seen on imaging to ‘disease’ and clinical symptoms is interesting. Gallstones are common and an incidence in excess of 10% in the population is described. It is common to find gallstones in an otherwise asymptomatic patient. My policy is to tell patients that they have gallstones even if they have no symptoms, however I am always concerned that patients will then develop symptoms. I am always surprised how patients can have significant radiological pathology and have so few symptoms. The patient had obvious gallstones, a thickened gallbladder wall, biliary dilatation and many CBD stones and yet had only itching with a history of itching. The story of painless jaundice would be more suggestive of pancreatic malignancy or a drug reaction rather than gallstones.

Her initial presentation was during a consultation made by her husband. Her symptoms seem relatively minor yet the biochemistry results are quite abnormal indicating a pattern of obstructive jaundice. Her ultrasound findings are dramatic with stones seen in the gallbladder and in the lower common bile duct (CBD). Ultrasound is the first-line investigation for the gallbladder and biliary tree. The ultrasound scan should be available with only a short wait for more urgent cases. This patient should be prioritised for an urgent scan appointment.

Her biliary tree is dilated with both intrahepatic and extrahepatic biliary dilatation. Her CBD measured 11 mm. This is a pathologically dilated CBD. In over 95% of young normal subjects the common bile duct measures less than 4mm. In the presence of gallstones the CBD can measure up to 7mm without implying obstruction. The CBD can also dilate in the elderly secondary to degeneration in the ductal wall and reach diameters of up to 9mm. The CBD can also change in size physiologically in relation to meals. In this patient there were gallstones readily visible in the lower CBD on ultrasound. A diameter of the CBD of over 10mm is definitely abnormal and will suggest the presence of stones in the CBD. In assessing the CBD for stones, if ductal stones are seen then stones are present. If CBD stones are not seen then this does not mean that they are absent since there is a significant rate of false negative results, partly related to the presence of obscuring gas in the duodenum.

The appearances of the liver are unexplained. Ultrasound is good for assessing focal liver disease. A common abnormal pattern is the geographical echogenic appearance seen in fatty change of the liver.

Competing interests: I am a commentator on this interactive case and will receive an honorarium from the BMJ. I am a radiologist working in the same hospitals that the patient attended.