Objective: The purpose of our study was to determine the prevalence of the "patent track" sign on Doppler sonography after percutaneous liver biopsy and to assess its value in detection of postbiopsy bleeding.
Subjects and methods: The study group included 352 patients who underwent Doppler sonography after 361 percutaneous liver biopsies. Color-flow images were obtained immediately and 5 minutes after the biopsies. Images were evaluated for the patent track sign, defined as linear color flow along the needle path. Patients were followed-up with clinical and laboratory findings to search for postbiopsy bleeding. Those suspected of having postbiopsy bleeding underwent CT. Sonographic results were compared with clinical and CT findings.
Results: Clinically significant postbiopsy bleeding occurred in five patients (1%). On Doppler sonography immediately after the biopsies, the patent track sign was seen in 43 patients (12%). Patients with this sign more frequently bled than those without it (p = 0.0008). Sensitivity, specificity, positive predictive values, and negative predictive values in detection of postbiopsy bleeding were 80%, 89%, 9%, and 100%, respectively. Among these patients, this sign was persistently seen in four and disappeared in the remaining 39 at 5 minutes after the biopsies. Patients with a persistent patent track sign more frequently bled than those without it (p < 0.0001). Sensitivity, specificity, positive predictive value, and negative predictive value were 60%, 100%, 75%, and 99%, respectively.
Conclusion: A patent track sign, frequently seen on Doppler sonography immediately after percutaneous liver biopsy, provides excellent screening for postbiopsy bleeding. This sign strongly predicts postbiopsy bleeding when persistently seen for 5 minutes.