A prospective study of consecutive patients presenting with acute abdominal pain investigated the use of a rapid acquisition noncontrast MRI protocol for determining the source of abdominal pathology [36]. The MRI was positive in 116 of 349 cases and indeterminate in 3 cases. Overall accuracy was 99% and only 3 cases with negative MRIs later required appendectomies. A range of pathologies were detected, including SBO, diverticulitis, pelvic inflammatory disease, pyelonephritis, renal abscess, pseudomembranous colitis, and diverticular abscess. A rapid MRI protocol may be beneficial in this setting. In a separate retrospective study of MRI with IV contrast in patients with pelvic pain, MRI depicted acute appendicitis with 100% sensitivity and 92% positive predictive value and ovarian torsion with a sensitivity of 86% and specificity of 100% [37]. Given its accuracy for a range of intra-abdominal pathologies [36,37], as well as the feasibility of distinguishing infected from noninfected fluid [38], MRI may be used as an alternative to CT. It should be noted that, in practice, the feasibility of MRI for acute abdominal pain will rely on institutional expertise, availability, and adoption of protocols that are aimed at rapid acquisition and multiorgan assessment, such as that used in the study by Byott and Harris [36]. US Abdomen Ultrasound (US) in general is less sensitive and specific than CT for nonlocalized abdominal pain workup. One retrospective review of 92 patients who underwent multiple studies to specifically evaluate for an intra-abdominal abscess demonstrated a sensitivity and specificity for US of 75% and 91%, respectively, compared to 88% and 93%, respectively, for CT [39].
Acute Nonlocalized Abdominal Pain. A prospective study of consecutive patients presenting with acute abdominal pain investigated the use of a rapid acquisition noncontrast MRI protocol for determining the source of abdominal pathology [36]. The MRI was positive in 116 of 349 cases and indeterminate in 3 cases. Overall accuracy was 99% and only 3 cases with negative MRIs later required appendectomies. A range of pathologies were detected, including SBO, diverticulitis, pelvic inflammatory disease, pyelonephritis, renal abscess, pseudomembranous colitis, and diverticular abscess. A rapid MRI protocol may be beneficial in this setting. In a separate retrospective study of MRI with IV contrast in patients with pelvic pain, MRI depicted acute appendicitis with 100% sensitivity and 92% positive predictive value and ovarian torsion with a sensitivity of 86% and specificity of 100% [37]. Given its accuracy for a range of intra-abdominal pathologies [36,37], as well as the feasibility of distinguishing infected from noninfected fluid [38], MRI may be used as an alternative to CT. It should be noted that, in practice, the feasibility of MRI for acute abdominal pain will rely on institutional expertise, availability, and adoption of protocols that are aimed at rapid acquisition and multiorgan assessment, such as that used in the study by Byott and Harris [36]. US Abdomen Ultrasound (US) in general is less sensitive and specific than CT for nonlocalized abdominal pain workup. One retrospective review of 92 patients who underwent multiple studies to specifically evaluate for an intra-abdominal abscess demonstrated a sensitivity and specificity for US of 75% and 91%, respectively, compared to 88% and 93%, respectively, for CT [39].