CT Abdomen and Pelvis CT of the abdomen and pelvis with IV contrast is often the first study and generally considered to be an optimal imaging modality for the evaluation of pain and suspected abscess in the postoperative patient. One study assessing the use of positive oral and IV contrast-enhanced CT scans obtained in all patients with suspected abscesses between 3 and 30 days demonstrated a similar diagnostic yield regardless of whether the scan was performed in the first postoperative week or later [23]. However, it is important to recognize that clinical suspicion can impact diagnostic yield. A retrospective study looking at postoperative patients after colorectal resection revealed that nearly 75% of patients with clinical concern for an infection will have a fluid collection, but many of these will not represent abscesses. Of the clinical, laboratory, and radiologic parameters studied, only a high index of clinical suspicion and close proximity of the fluid collection to the site of surgery were associated with predicting an infected collection [52]. In a retrospective review of elective pancreatic resections, intra- abdominal infections were diagnosed at a mean of 11.8 days following the procedure; notably, abdominal pain and peritonitis were uncommon presentations and early postoperative CT was encouraged in any patient presenting with fever and sepsis [53]. In the setting of colorectal anastomoses, one study evaluating 36 patients with proven leaks demonstrated water- soluble enema may have better sensitivity for detecting distal anastomotic leaks than CT (88% versus 12%, P <. 001), but in a very small number of patients (n = 10) neither was sensitive for a leak if the patient had a proximal colonic anastomosis [47]. CT can also help diagnose other causes of postoperative abdominal pain, including omental infarction or torsion [54].
Acute Nonlocalized Abdominal Pain. CT Abdomen and Pelvis CT of the abdomen and pelvis with IV contrast is often the first study and generally considered to be an optimal imaging modality for the evaluation of pain and suspected abscess in the postoperative patient. One study assessing the use of positive oral and IV contrast-enhanced CT scans obtained in all patients with suspected abscesses between 3 and 30 days demonstrated a similar diagnostic yield regardless of whether the scan was performed in the first postoperative week or later [23]. However, it is important to recognize that clinical suspicion can impact diagnostic yield. A retrospective study looking at postoperative patients after colorectal resection revealed that nearly 75% of patients with clinical concern for an infection will have a fluid collection, but many of these will not represent abscesses. Of the clinical, laboratory, and radiologic parameters studied, only a high index of clinical suspicion and close proximity of the fluid collection to the site of surgery were associated with predicting an infected collection [52]. In a retrospective review of elective pancreatic resections, intra- abdominal infections were diagnosed at a mean of 11.8 days following the procedure; notably, abdominal pain and peritonitis were uncommon presentations and early postoperative CT was encouraged in any patient presenting with fever and sepsis [53]. In the setting of colorectal anastomoses, one study evaluating 36 patients with proven leaks demonstrated water- soluble enema may have better sensitivity for detecting distal anastomotic leaks than CT (88% versus 12%, P <. 001), but in a very small number of patients (n = 10) neither was sensitive for a leak if the patient had a proximal colonic anastomosis [47]. CT can also help diagnose other causes of postoperative abdominal pain, including omental infarction or torsion [54].