Sonographic versus endoscopic retrograde cholangiographic measurements of the bile duct revisited: importance of the transverse diameter

Ultrasound measurements of the bile ducts and gallbladder: normal ranges and effects of age, sex, cholecystectomy, and pathologic states

OBJECTIVE

The objectives of this study were to determine the normal values and ranges for bile duct and gallbladder measurements, adjusted for demographic data, and to assess the effects of a variety of pathologic states on these values.

METHODS

Four thousand one hundred nineteen abdominal ultrasounds were retrospectively analyzed. The values for the extrahepatic bile duct (EHD), left (LIHD) and right (RIHD) intrahepatic ducts, gallbladder wall thickness, and gallbladder volume in "normal" patients were evaluated with respect to age, sex, ethnicity, and cholecystectomy status. These values were compared using multivariate analysis to those in a variety of diseased states, including cirrhosis, fatty liver, gallstones, sludge, cholecystitis, and biliary obstruction.

RESULTS

One thousand four hundred eighty-four of the 4119 examinations were classified as normal. The mean EHD, RIHD, LIHD, and gallbladder wall thickness and volume measurements in normal patients were 3.8 ± 1.6 mm, 1.9 ± 1.9 mm, 1.9 ± 1.1 mm, 2.6 ± 1.6 mm, and 242 ± 234 mL, respectively.There were small increases in EHD diameter with age (+0.02 ± 0.11 mm/y, P < 0.001), female sex (+0.3 ± 1.6 mm, P < 0.0001), and cholecystectomy (+1.0 ± 1.6 mm, P < 0.0001) and a small decrease with fatty liver (-0.4 ± 1.6 mm, P = 0.0003). The gallbladder wall was thicker in patients with gallstones (+0.4 ± 1.4 mm, P = 0.0049), sludge (+0.5 ± 1.4 mm, P = 0.0019), and acute cholecystitis (+3.1 ± 1.6 mm, P < 0.0001). With biliary obstruction, the mean EHD, RIHD, LIHD, and gallbladder volume measurements were 6.0 ± 2.1 mm, 4.2 ± 1.4 mm, 4.1 ± 1.4 mm, and 171 ± 207 mL, respectively (P < 0.0001 for all values).

CONCLUSIONS

This study clarifies normal values and ranges for bile duct and gallbladder measurements, adjusted for demographic data, and evaluates these measurements in a variety of common pathologic states.

Dynamic changes of common bile duct diameter during an episode of biliary colic, documented by ultrasonography

Common bile duct stones frequently accompany gallstones and can be identified by a variety of imaging modalities. Little is known about the time course of dilatation of the common bile duct after acute obstruction or of normalization after spontaneous passage of an obstructing stone. We describe a case showing rapid fluctuations in common bile duct diameter during 72 hours in a patient presenting with epigastric pain and vomiting. Initial emergency bedside ultrasonography revealed a distended gallbladder, a dilated common bile duct (17 mm), and an obstructing stone. Five hours later, ultrasonography performed in the radiology suite showed a normal common bile duct diameter (4 mm) and no obstructing stone. The patient was admitted, and during the course of hospitalization different imaging modalities reported fluctuations in common bile duct measurements, ranging from 4 mm on computed tomography to 14 mm on endoscopic retrograde cholangiopancreatography. This case demonstrates disappearance of an obstructing stone with normalization of a highly distended common bile duct during 5 hours, highlighting that gallstone disease may be highly dynamic, with the possibility of rapid changes of common bile duct diameter. Emergency physicians, who frequently depend on ultrasonography to diagnose biliary disease, should be wary of the potential for rapid changes of sonographic findings in these patients.

Update of cholangioscopy and biliary strictures

Cholangioscopy remains another modality in the investigation of biliary strictures. At cholangioscopy, the “tumour vessel” sign is considered a specific sign for malignancy. Through its ability to not only visualise mucosa, but to take targeted biopsies, it has a greater accuracy, sensitivity and specificity for malignant strictures than endoscopic retrograde cholangiopancreatography guided cytopathological acquisition. Cholangioscopy however, is time consuming and costly, requires greater technical expertise, and should be reserved for the investigation of undifferentiated strictures after standard investigations have failed.

Ultrasound of the extrahepatic bile duct: issues of size

Ultrasound is a pivotal study for evaluation of the biliary tree. In particular, the size of the extrahepatic bile duct is a critical measurement and has been a contentious issue since the early days of diagnostic ultrasound. This article reviews the history and ongoing issues regarding sonography of the normal-size duct and a variety of factors that may affect its size, including age, prior surgery, congenital abnormalities, anatomical variations, and medications. Other related sonographic issues are discussed including abnormal nondilated ducts and abnormal intraluminal contents such as sludge or air that make evaluation of the duct more difficult, particularly in patients with primary sclerosing cholangitis and prior liver transplantation. Ultimately, the luminal size of the extrahepatic duct should be considered as a single part of the entire assessment of the biliary tree that must also include the intrahepatic and pancreatic ducts, the pattern of dilatation (variable vs progressively dilated to a single point of obstruction), any wall thickening, intraluminal sludge, calculi or mass, and extraluminal compression. Clinical symptoms and abnormal laboratory values should prompt further evaluation despite a normal appearance of the bile duct, whereas pursuit of an isolated finding of an enlarged duct without supporting clinical data may not be warranted.

Diagnosis and management of acute cholangitis

Bacterial infection that occurs in the setting of biliary obstruction can lead to acute cholangitis, a condition characterized by fever, abdominal pain and jaundice. Choledocholithiasis is the most common cause of acute cholangitis and is often associated with bacterial infection and colonization in addition to biliary obstruction. Iatrogenic introduction of bacteria into the biliary system most commonly occurs during endoscopic retrograde cholangiopancreatography in patients with biliary obstruction. The majority of patients with acute cholangitis respond to antibiotic therapy, but endoscopic biliary drainage is ultimately required to treat the underlying obstruction. Acute cholangitis is often diagnosed using the clinical Charcot triad criteria; however, recommendations from an international consensus meeting in Tokyo produced the most comprehensive recommendations for the diagnosis and management of acute cholangitis. These guidelines enable a more accurate diagnosis of acute cholangitis than do earlier methods, and they facilitate the classification of disease as mild, moderate or severe. Although these guidelines represent a notable advance toward defining a universally accepted consensus for the definition of acute cholangitis, they have several limitations. This Review discusses current recommendations for the diagnosis of acute cholangitis and addresses the advantages and disadvantages of different modalities for the treatment of this disease.

Pancreaticobiliary maljunction without bile duct dilatation in children: distinction from choledochal cyst

OBJECTIVES

Pancreaticobiliary maljunction without bile duct dilatation (nondilated type) is rare in children, and its definition remains unclear. There is controversy over treatment between pediatric and adult patients. We reevaluated our previous definition of the nondilated type in children (common bile duct diameter <or=6 mm on cholangiography).

PATIENTS AND METHODS

Of 150 children with pancreaticobiliary maljunction, 14 fulfilled the definition of the nondilated type. Clinical and cholangiographic findings were reviewed and compared with cholangiograms of 17 children without biliary diseases (controls). The age-related normal range of the choledochal diameter was defined in combination with previous data.

RESULTS

All of the patients had symptoms and signs similar to those of choledochal cysts. Cholangiographic features of choledochal cysts were detected in all of the patients (dilated common channel, 8; distal bile duct stenosis, 5; dilated cystic duct, 4; filling defect in the common channel, 8). The choledochal diameter in control children increased with age. Only 4 patients (29%) had a choledochal caliber within the normal range.

CONCLUSIONS

Most pediatric cases reported as the nondilated type are slightly dilated (forme fruste) choledochal cysts and differ from the nondilated type seen in adults. The nondilated type in children should be defined on the basis of the age-related choledochal diameter.

Difference of CBD width on US vs. ERCP

PURPOSE

To investigate the relationship between US and ERCP in the measurement of common bile duct (CBD) width after application of Compound and Harmonic imaging on ultrasound.

METHODS

We prospectively evaluated the CBD width as measured on endoscopic retrograde cholangiopancreatography (ERCP) and ultrasonography (US), applying Compound and Harmonic US techniques, on 100 patients. Furthermore, we retrospectively re-examined US and ERCP images of 48 patients who underwent ERCP and US during the same hospitalization period.

RESULTS

The average difference in measurements by US compared to ERCP was 2.3 mm (P < 0.01) in the retrospective and 1.9 mm in the prospective study (P < 0.001). The average difference in measurements between US and ERCP in post-cholecystectomy patients was 4.0 mm in the retrospective study (10 patients), and 3.8 in the prospective study (25 patients). The difference between the measurements on both examinations decreased with increasing CBD width. There was a good correlation between ERCP and US measurements of CBD width (r = 0.73 for all patients and r = 0.88 for patients with intact gallbladder, P < 0.001).

CONCLUSIONS

There is a gap between measurement of CBD width on US and ERCP of about 2 mm. The application of Compound and Harmonic techniques in the prospective study probably enabled a more accurate sonographic measurement.

Three-dimensional sonographic evaluation of the common bile duct

OBJECTIVE

To assess the accuracy of three-dimensional sonographic measurements of the common bile duct compared with standard two-dimensional anteroposterior measurement of the common duct.

METHODS

Fifty-five consecutive patients referred for abdominal sonography underwent standard two-dimensional abdominal sonography followed by three-dimensional sonographic data acquisition of the right upper quadrant. A radiologist blinded to the results of the two-dimensional examination later measured the three-dimensional long axis anteroposterior common duct diameter and three-dimensional short axis anteroposterior and transverse common duct diameters.

RESULTS

The mean average common duct diameter as measured by two-dimensional sonography (long axis anteroposterior) was 3.6 mm. The mean average common duct diameter as measured by long axis anteroposterior three-dimensional sonography was 4.1 mm. The mean average common duct diameter as measured by anteroposterior short axis three-dimensional sonography was 4.1 mm, and by transverse short axis three-dimensional sonography, it was 4.4 mm. The two-dimensional common duct measurement correlated with the long axis anteroposterior three-dimensional measurement (P < .001), the short axis anteroposterior three-dimensional measurement (P < .001), and the short axis transverse three-dimensional measurement (P < .005) by the Spearman rank order correlation coefficient test.

CONCLUSIONS

Three-dimensional sonographic measurements of the common bile duct correlate highly with two-dimensional measurements, validating the use of three-dimensional sonography as a reliable method for evaluation of common bile duct size.

A prospective comparison of the diagnostic accuracy of ERCP, MRCP, CT, and EUS in biliary strictures

BACKGROUND

The differential diagnosis of biliary strictures remains a challenge. This study evaluated magnetic resonance cholangiopancreatography (MRCP) as a new procedure in comparison with the established methods of diagnosis including ERCP or percutaneous transhepatic cholangiography (PTC), CT, and EUS.

METHODS

Fifty patients (21 men, 29 women, mean age 65.7 years) with jaundice but no pain suspected to have biliary strictures were enrolled in this prospective study. MRCP, ERCP/PTC, CT, and EUS were performed prospectively; images and videotapes (EUS) of these tests were reviewed blindly under standardized conditions. Reference standards for comparison were surgery, a biopsy confirming malignancy, or the clinical course during follow-up (at least 12 months) in cases without histopathologic proof of malignancy.

RESULTS

Seven patients ultimately proved to have jaundice caused by parenchymal liver disease and 43 had a biliary stricture (17 benign, 26 malignant). Forty patients underwent all 4 imaging tests. There were 10 patients in whom patient-specific problems precluded some procedures but who were included in an intention-to-diagnose analysis. The sensitivity and specificity for diagnosis of malignancy in the 50 patients were as follows: 85% / 75% for ERCP/PTC, 85% / 71% for MRCP, 77% / 63% for CT, and 79% / 62% for EUS, with similar values in the 40 patients who underwent all 4 imaging methods. The combination of MRCP and EUS improved specificity.

CONCLUSIONS

Although MRCP provides the same imaging information as direct cholangiography, it has limited specificity for the diagnosis of malignant strictures. In the differential diagnosis of biliary strictures, several tests including ERCP-guided tissue diagnosis are still required, and MRCP has only a limited clinical role.

Is age associated with size of adult extrahepatic bile duct: sonographic study

PURPOSE

To determine if the size of the extrahepatic bile duct increases with age in adults.

MATERIALS AND METHODS

A total of 258 consecutive patients 18 years and older, without known biliary or pancreatic disease, who were fasting to undergo routine abdominal sonography were examined. The transverse and anteroposterior dimensions of the extrahepatic bile duct were measured proximally at the porta hepatis, at the middle above the head of the pancreas, and distally at the head of the pancreas. Simple linear regression of the average of these measurements against age tested the hypothesis of a slope of 1.0 mm per decade.

RESULTS

The sample included a wide variety of ages: 55 years +/- 16 (mean +/- SD), with a range of 20-92 years, including 151 men and 107 women. One-tenth of the cohort were younger than 35 years old and one-tenth were older than 77 years old. The six measurements were proximal-transverse 3.5 mm +/- 1.0, proximal-anteroposterior 2.9 mm +/- 1.1, middle-transverse 3.9 mm +/- 1.2, middle-anteroposterior 3.4 mm +/- 1.2, distal-transverse 4.1 mm +/- 1.2, distal-anteroposterior 3.5 mm +/- 1.2. Least squares regression slope differed significantly from 0.1 mm per year (95% CI; -0.000703, +0.00110) and in fact contained zero.

CONCLUSION

Findings were not able to help confirm an association between age and size of the extrahepatic bile duct in an asymptomatic adult population.