The Utility of Abdominal Ultrasound Following Negative Computed Tomography in Diagnosing Acute Pancreatitis

Aim Acute pancreatitis is a diagnosis established by fulfillment of at least two out of three clinical features, including epigastric pain, elevated lipase, and/or radiographic evidence of acute pancreatitis. Computed tomography of the abdomen and pelvis (CTAP) is the gold standard imaging modality for evaluating acute pancreatitis. Although abdominal ultrasound (AUS) is increasingly utilized given the widespread availability and high sensitivity and specificity for detecting gallstone-related complications, including gallstone pancreatitis, the leading cause of acute pancreatitis in the US. However, recent literature has concluded that performing AUS following a negative CTAP rarely led to changes in management and imparted an increased length of service (LOS) in the ED. Our study investigated whether a similar relationship was observed when managing acute pancreatitis in the inpatient setting. We aimed to quantify how performing AUS influenced inpatient LOS for patients admitted for acute pancreatitis without radiographic evidence of acute pancreatitis on CTAP. We also aimed to quantify how AUS influenced the likelihood of subsequent intervention via endoscopic retrograde cholangiopancreatography (ERCP) or cholecystectomy, including the relative impact of certain demographic or clinical features. Methods A retrospective analysis was performed using a cohort of 6069 patient encounters extracted via the HCA Healthcare enterprise data warehouse (EDW) database. Inclusion criteria were all adult patients with an index admission for acute pancreatitis between January 1 and December 31, 2019, who underwent CTAP during admission. Patients younger than 18 years, with prior cholecystectomy, or without documentation of demographic or clinical data of interest were excluded. The primary outcome was to quantify how performing AUS within 48 hours impacted LOS for patients admitted for acute pancreatitis following negative CTAP. Secondary outcomes examined whether AUS changed management (i.e., per likelihood of subsequent ERCP or cholecystectomy). This included determining the influence of various demographic or clinical characteristics on the likelihood of intervention via ERCP or cholecystectomy. Linear regression was used to determine the effect of performing AUS on the duration of LOS. Logistic regression was used for covariate analysis based on demographic (BMI, sex, race, age) and clinical data (comorbid conditions, abnormal labs, and vital signs). Results Patients with acute pancreatitis who underwent AUS within 48 hours had a reduced LOS of 1.099 days. Patients who underwent AUS were 1.126 times more likely to undergo subsequent ERCP than those who received CTAP alone. Patients who received AUS following CTAP were also 2.711 times more likely to undergo subsequent cholecystectomy. Increasing age and BMI were correlated with an increased likelihood of ERCP and cholecystectomy. Males were less likely to undergo cholecystectomy (OR = 0.753) and ERCP (OR = 0.815) compared to females. Conclusion Performing AUS within 48 hours following negative CTAP in this cohort of patients admitted for acute pancreatitis was associated with a decreased LOS. Furthermore, patients who underwent AUS were more likely to undergo ERCP and even more likely to undergo cholecystectomy. The likelihood of ERCP and cholecystectomy increased proportionally to both age and BMI. Females were more likely than males to undergo subsequent ERCP or cholecystectomy.