Brian P. Jacob, David C. Chen, Bruce Ramshaw, Shirin Towfigh (eds.) - The SAGES Manual of Groin Pain-Springer International Publishing (2016)

178
J.M. Miller et al.
Fig. 13.4. Axial and coronal CT images displaying a case of perforated appendicitis.
The tubular shape of the appendix ( asterisks ) is clearly seen in the coronal
view with a high-density fecalith ( black arrow ) best seen on the axial view.
Gas ( curved black arrow ) within the surrounding fluid collection ( surrounded
by white arrows ) is consistent with peri- appendiceal abscess formation.
glomerular filtration rate appears to be the primary determinant of acute
kidney injury. Current iodinated contrast materials have been found to
not represent an independent risk factor for AKI even among patients
with impaired GFR (below 30 mL/min/1.73 m 2 ) [5 ]. It bears mentioning
that this research is relatively recent and requires independent confirmation
before current practice guidelines will change [ 6 ]. The suggestion,
however, is that the administration of iodinated contrast material should
not be avoided in otherwise healthy individuals. While intravenous contrast
material is not required for most protocols, it increases the ability of
CT to evaluate for all manner of infectious, inflammatory, and neoplastic
processes (Figs. 13.5 , 13.6 , and 13.7 ). Likewise, abdominopelvic
evaluation by CT benefits substantially from routine oral contrast
administration (Fig. 13.8 ). While rectal contrast agents also have utility,
improvements in image resolution and multiplanar reformatting are leading
to decreased reliance on such invasive administration.
CT contrast reactions are infrequent occurrences that are incompletely
understood. In the majority of patients, reactions to iodinated contrast are
not allergies in the traditional sense of IgE mediation, yet may present
with anaphylactoid airway edema or other severe physiologic consequences
all the same [ 7 ]. As per the above discussion of contrast-induced
nephropathy, the incidence of severe adverse reactions has decreased
substantially since the switch was made to low osmolarity contrast material
[ 8 ]. A history of asthma or prior contrast reaction increases the risk
of acute reaction. Pretreatment with oral corticosteroids is recommended
for at-risk patients [ 9 ]. Common pretreatment regimens for high- risk
individuals may involve oral administration of 50 mg prednisone at 13,