• Delayed Enhancement of Ascites After IV Contrast Material Administration at CT: Time Course and Clinical Correlation

    AJR:193, September 2009

    Nancy Benedetti, Rizwan Aslam Zhen J. Wang Bonnie N.Joe Yanjun Fu Judy Yee Benjamin M. Yeh

    OBJECTIVE. The objective of our study was to determine the prevalence and clinical predictors of delayed contrast enhancement of ascites.

    MATERIALS AND METHODS. In this retrospective study, 132 consecutive patients with ascites who underwent repeated abdominopelvic CT examinations performed within 7 days of each other were identified. These patients included 112 patients who received and 20 who did not receive IV contrast material at the initial CT examination. For each examination, we recorded the CT attenuation of the ascites. For the follow-up scan, the presence of delayed enhancement of ascites was defined as an increase in CT attenuation > 10 HU over baseline. The Fisher's exact test, unpaired Student's t test, and logistic regression were used to deter­mine predictors of delayed enhancement of ascites.

    RESULTS. A threshold increase in the attenuation of ascites by > 10 HU or more between the initial and follow-up CT examinations occurred only when IV contrast material was given with the initial examination. The increased attenuation was due to delayed contrast enhance­ment of ascites and occurred in 15 of the 112 patients (13%). Of the 16 patients scanned less than 1 day apart, 10 (63%) showed delayed enhancement of ascites. Delayed enhancement was not observed 3 or more days after IV contrast material administration. For each 1 mg/ dL increase in serum creatinine level, the likelihood of delayed enhancement of ascites in­creased (odds ratio, 2.02; 95% CI, 1.11-3.69). Multivariate logistic regression showed that a short time interval between examinations (p < 0.001), increased serum creatinine level (p < 0.001), and presence of loculated ascites (p = < 0.01) were independent predictors of the mag­nitude of delayed enhancement of ascites.

    CONCLUSION. Delayed contrast enhancement of ascites occurs commonly after re­cent prior IV contrast material administration and should not be mistaken for hemoperitone-um or proteinaceous fluid such as pus.