Intra-Abdominal Infections

One of the highest-profile articles published this year concerned the use of antibiotics for appendicitis.⁵ Several earlier studies indicated a nonsurgical approach is safe, and a majority of patients have a durable long-term avoidance of appendectomy. However, the proportion of patients who do ultimately require an appendectomy remains nontrivial, leaving many still finding value in an initial surgical strategy. The most important insight from this most recent trial is the role an appendicolith identified on initial imaging plays in treatment failure. Of those who failed an initial nonsurgical approach, 41 percent had an appendicolith compared to only 25 percent of those without. These data further detail the information potentially incorporated into shared decision-making conversations.

As antibiotic treatment increases for appendicitis, a decrease in antibiotic use is being seen for diverticulitis. In yet another trial, patients with diverticulitis managed with and without antibiotics showed similar outcomes.⁶ This time, the patient population involved those admitted to the hospital with uncomplicated diverticulitis, using a primary outcome of in-hospital length of stay. Although there was no difference in this outcome, and no statistical difference in secondary adverse outcomes, it remains likely that a few patients benefit from antibiotics; figuring out which ones is not so easy though. As with appendicitis, additional data are necessary for teasing out any features of those patients for whom antibiotics play a role.

Advanced Imaging

Yet again, we find there is no clear mechanism to stave off so-called contrast-induced nephropathy (CIN) from CT imaging. The Kompas trial enrolled patients with stage 3 chronic kidney disease undergoing contrast-enhanced CT and found no benefit to the use of sodium bicarbonate infusion as prehydration.⁷ The authors conducting the trial concluded that withholding prehydration is safe and cost-effective. These data add yet another piece to the contrast imaging puzzle. The more data showing the futility of any intervention for reducing CIN we gather, the more difficult it becomes to paint a picture of imaging-associated CIN as a true disease entity—at least in the setting of emergency department imaging, where contrast doses are substantially smaller than in other situations, such as interventional radiologic procedures.

This is effectively the new stance adopted by a joint statement by the American College of Radiology and the National Kidney Foundation.⁸ In their statement, narrowly focused on patients receiving intravenous contrast for advanced imaging, they described a distinction between contrast-associated acute kidney injury and contrast-induced acute kidney injury. Contrast-associated acute kidney injury is common, but it’s seen as being related to the underlying medical illness rather than caused by the contrast administration itself. Their summary described inconsistent evidence supporting the existence of contrast-induced acute kidney injury, noting modern low-osmolar contrast media are less likely to be nephrotoxic than prior-generation products. Only those with the most severe renal impairment are seen as potentially reasonable candidates for gentle volume expansion prior to contrast administration prior to advanced imaging.