Correlation between sphincter of Oddi manometry and intraductal ultrasoundmorphology in patients with suspected sphincter of oddi dysfunction

Background and Study Aims: Intraductal ultrasonography (IDUS) makes it poss ible to study sphincter of Oddi morphology during endoscopy. Two recent IDU S studies have described the sphincter of Oddi as a circumferential hypoech oic layer in the papilla, but there have as yet been few published data fro m patients with suspected sphincter of Oddi pathology. Patients and Methods: Twenty-one consecutive patients with suspected biliar y sphincter of Oddi dysfunction (seven men, 14 women; age 54 +/- 17 years) were enrolled in the study. Endoscopic sphincter of Oddi manometry was carr ied out using a 4-Fr electronic microtransducer device. After this, a wire- guided 6-Fr ultrasound catheter was placed in the common bile duct (CBD), a nd IDUS was carried out while the ultrasound catheter was being withdrawn f rom the CBD toward the duodenum. Results: Sphincter of Oddi manometry and IDUS were carried out successfully in 18 of the 21 patients. Sphincter of Oddi manometry revealed sphincter o f Oddi hypertension (baseline pressure > 35 mmHg) in eight patients. The me an sphincter of Oddi baseline pressure was 32 +/- 17 mmHg, and the mean pha sic sphincter of Oddi pressure was 132 +/- 31 mmHg. During IDUS, a circumfe rential hypoechoic layer was clearly delineated in all patients. There was a significant correlation between the manometrically determined length of t he sphincter of Oddi (8 +/- 2 mm) and the thickness of the hypoechoic layer (6 +/- 2 mm) as assessed by IDUS (r = 0.66, P < 0.001). However, no correl ation was found between the baseline or phasic sphincter of Oddi pressures and the thickness of the hypoechoic layer. Accordingly, IDUS did not allow identification of patients with sphincter of Oddi hypertension. Mild pancre atitis was observed in one of the 18 patients (6%). Conclusions: The circumferential hypoechoic layer of the papilla visualized by IDUS is the ultrasonographic correlate of the sphincter of Oddi. IDUS o f the papilla is technically feasible and safe in patients with suspected s phincter of Oddi dysfunction. IDUS may provide additional information at th e sphincter of Oddi level, but cannot be used as a substitute for sphincter of Odd! manometry.