Thinking outside the box

Challenging clinical paradigms of common bile duct diameter

The incidence of choledocholithiasis is increasing. The diagnosis of common bile duct (CBD) obstruction is based on abnormal CBD size. Establishing norms for CBD size in children would improve diagnostic accuracy. We analyzed ultrasounds (US) to determine normal pediatric CBD size based on age and then validated this against patients with choledocholithiasis.

A retrospective review was conducted for children less than 21 years of age with US defined CBD size. Patients were stratified into age groups by ANOVA statistical analysis. Secondary analysis included patients with confirmed choledocholithiasis in comparison to the normal cohort.

A total of 778 patients had US without pathology. Group 1 (< 1 year) had a mean CBD of 1.24 ± 0.54 mm, group 2 (1–10 years) 1.97 ± 0.71 mm, and group 3 (> 10 years) 2.98 ± 1.17 mm, p < 0.05. Fourteen additional patients were found to have choledocholithiasis with a mean CBD size of 8.1 mm. All patients with choledocholithiasis had CBD sizes outside of our normal range, but only 50% of patients had enlarged CBD size based on adult normal range of values.

Normal CBD size in children is less than a normal adult patient. More accurate normal values will aid in determining if a child needs further evaluation for possible obstruction of the CBD.

Type of study: diagnostic

Level of evidence: III

Selection of patients with the highest probability for therapeutic ERCP remains an important task in a clinical workup of patients with suspected choledocholithiasis (CDL).

To determine whether an artificial neural network (ANN) model can improve the accuracy of selecting patients with a high probability of undergoing therapeutic ERCP among those with strong clinical suspicion of CDL and to compare it with our previously reported prediction model.

Prospective, observational study.

Single, tertiary-care endoscopy center.

Between January 2010 and September 2012, we prospectively recruited 291 consecutive patients who underwent ERCP after being referred to our center with firm suspicion for CDL.

Predictive scores for CDL based on a multivariate logistic regression model and ANN model.

The presence of common bile duct stones confirmed by ERCP.

There were 80.4% of patients with positive findings on ERCP. The area under the receiver-operating characteristic curve for our previously established multivariate logistic regression model was 0.787 (95% CI, 0.720-0.854; P < .001), whereas area under the curve for the ANN model was 0.884 (95% CI, 0.831-0.938; P < .001). The ANN model correctly classified 92.3% of patients with positive findings on ERCP and 69.6% patients with negative findings on ERCP.

Only those variables believed to be related to the outcome of interest were included. The majority of patients in our sample had positive findings on ERCP.

An ANN model has better discriminant ability and accuracy than a multivariate logistic regression model in selecting patients for therapeutic ERCP.