Incidence of Early and Late-Onset Clostridioides difficile Infection following Appendectomy Compared to Other Common Abdominal Surgical Procedures.

Introduction: Clostridioides difficile associated diarrhea (CDAD) is a major public health issue. The appendix may function as a reservoir for the intestinal microbiome, which may repopulate the intestine following enteric infections including CDAD. Patients/Methods. This retrospective cohort study includes a total of 12,039 patients undergoing appendectomy, hemicolectomy, and cholecystectomy at a single center between 1992 and 2011 who were diagnosed with early and late-onset CDAD and were followed for a minimum of two years. Results: Cumulative CDAD rates were 2.3% after appendectomy, 6.4% after left and 6.8% after right hemicolectomy, and 4% after cholecystectomy with a median onset of 76 (range 1-6011) days after the procedure. Median time to CDAD onset was 76 days after appendectomy, 23 days after left, 54 days after right hemicolectomy, and 122 days after cholecystectomy (p < 0.05). Late-onset CDAD (>1 year) was significantly more common following appendectomy (37%) and cholecystectomy (39%) than after left (17%) and right (21%) hemicolectomy. Significant differences in age, gender, complication rate, and length of hospitalization between the four groups need to be considered when interpreting the results. Conclusion: The incidence of CDAD after various abdominal surgeries ranged between 2% and 7% in this study. Whereas, hemicolectomy patients had predominantly early onset CDAD, and appendectomy and cholecystectomy may increase the risk for late-onset CDAD. Appendectomy per se does not seem to increase the risk for late-onset CDAD.

Pulmonary blood volume imaging with dual-energy computed tomography: spectrum of findings.

Dual-energy (DE) pulmonary blood volume (PBV) computed tomography (CT) has recently become available on clinical CT systems. The underlying physical principle of DECT is the fact that the photoelectric effect is strongly dependent on the CT energies resulting in different degrees of x-ray attenuation for different materials at different energy levels. DECT thus enables the characterization and quantification of iodine within tissues via imaging at different x-ray energies and analysis of attenuation differences. Technical approaches to DECT include dual-source scanners acquiring two scans with different energy levels simultaneously, and single-source CT scanners using sandwich detectors or rapid voltage switching. DE PBV CT enables the creation of iodine maps of the pulmonary parenchyma. Experience to date shows that these studies can provide additional physiological information in patients with acute or chronic pulmonary embolism beyond the pure morphological assessment a standard CT pulmonary angiography (CTPA) provides. It appears also to be promising for the evaluation of patients with obstructive airways disease. This article reviews the physics and technical aspects of DE PBV CT as well as the appearance of normal and abnormal lung tissue on these studies. Special consideration is given to pitfalls and artefacts.