Background: This study was done to determine the effects of duration of obstruction on severity of lesions in patients with acute pancreatitis of biliary origin.
Study design: This case controlled study used patient data collected prospectively on protocol during a 27-year period in a university teaching hospital. We studied a group of 97 patients with acute pancreatitis, all with an impacted stone at the ampulla of Vater at exploration (Group Ob), and a control group of 49 patients with acute gallstone pancreatitis who experienced spontaneous ampullary disobstruction within 24 hours from the onset of symptoms and who showed a patent ampulla at exploration (Group Cont). Duration of obstruction was defined as the time elapsed between the onset of symptoms and exploration in Group Ob, and from the onset of symptoms until the appearance of signs of ampullary disobstruction in Group Cont. Severity of disease in both groups was determined by the appearance of the pancreas at exploration. Patients in Group Ob were divided into three subgroups according to duration of obstruction: under 24 hours, 25 to 48 hours, and more than 48 hours.
Results: The incidence of severe pancreatic lesions was higher in Group Ob than in Group Cont (19.7 percent compared to 6.1 percent, p < .01). Mean duration of obstruction was also significantly longer in Group Ob than in Group Cont (42.4 hours compared to 10.6 hours). In the subgroups of patients whose obstruction lasted under 48 hours, the incidence of severe lesions was low: in the 24 hours or fewer group, severe lesions were observed in 8.1 percent (3 of 37); and in the 25 to 48 hours group, the incidence was 10.6 percent (5 of 47). Neither subgroup differed significantly from Group Cont (6.1 percent, 3 of 49). When duration of obstruction exceeded 48 hours, however, frequency of severe lesions increased significantly to 84.6 percent (11 of 13) (p < .001).
Conclusions: The findings in this study suggest that duration of ampullary obstruction is a major factor determining the severity of pancreatic lesions: severe pancreatic lesions are rare in patients whose obstruction lasts not more than 48 hours. In contrast, pancreatic necrosis develops in nearly all patients with obstruction beyond 48 hours. It may be safe to treat patients conservatively during the first day of the illness. If obstruction is not resolved by the second day, endoscopic retrograde cholangiopancreatography or surgical intervention must be carried out.