The learning curve of intestinal ultrasonography in assessing inflammatory bowel disease

Purpose: It is still unknown how much training is required in order to become competent to perform intestinal US. The aim of our study is to assess the intestinal US learning curve for physicians.

Material and methods: This is a prospective cohort study of 6 trainees, 3 trained in abdominal US (more > 500 exams), but not in intestinal US and 3 with little experience in US, undertaking an intestinal US fellowship. Participants initially underwent a theoretical course in the use of US in intestinal disorders (8 hours), followed by a one-week training period (50 – 60 exams). Trainees then independently assessed > 100 (100 – 152) patients with abdominal symptoms or firm or suspected inflammatory bowel disease and recorded the results concerning several US parameters including increased bowel wall thickness (> 4 mm) and small bowel dilatation (> 25 mm), and enlarged mesenteric lymph nodes (minor diameter > 4 mm) on a data sheet, which was compared to that of a physician experienced in bowel US (> 30.000 exams). Statistical analysis was performed by K statistics, subdivided in 3 cluster of 33 – 50 patients (k value: 0 = poor to 1 = excellent agreement).

Results: After accounting for clustering of exams by operator, we showed that physicians previously trained in abdominal US and physicians with little experience in US, had a variable and increasing agreement with the experienced physician. K-values for different operators from the first to the third clusters of patients, for detection of increased wall thickness, enlarged lymph nodes and abnormal bowel dilatation are shown in Table 1.

Tab. 1:

Operators	#1*	#2	#3*	#4*	#5	#6	Mean
Increased wall thickness
Set 1	0.94	0.76	0.60	0.82	0.63	0.94	0.78
Set 2	1	0.86	0.94	1	1	0.51	0.89
Set 3	1	1	1	1	1	0.93	0.98
Abnormal dilatation
Set 1	1	0.72	1	0.90	0.42	1	0.84
Set 2	1	1	1	1	0.45	0.63	0.85
Set 3	1	1	1	1	1	0.84	0.97
Enlarged mesenteric lymph nodes
Set 1	0.81	0.37	0.46	0.69	0.50	0.02	0.48
Set 2	1	1	1	0.72	0.48	0.24	0.74
Set 3	1	1	0.93	0.89	0.77	0.81	0.90
* physicians trained in abdominal US.

Conclusion: Physicians previously trained in abdominal US were able to achieve competency sooner than those with no previous experience in US. All physicians showed an increasing agreement with experienced sonographer during their training and achieved competency in intestinal US after 150 supervised examinations.