If there is clinical suspicion for splenic infarction, a basic set of labs, including a complete blood count (CBC), electrolytes, blood cultures, and a lactate dehydrogenase (LDH) level, should be drawn. Leukocytosis and positive blood cultures indicate possible infective endocarditis, and elevated LDH is present in 71% of patients with splenic infarction.6
An abdominal ultrasound is an easy first-line modality, but is highly operator dependent and limited by intra-abdominal gas and body habitus. An intercostal approach is usually taken postero-laterally along the long axis of the 10th rib. Normal splenic parenchyma appears homogeneous, with reflectivity slightly lower than hepatic parenchyma.11 In one study that used both CT and ultrasound for diagnosing splenic infarcts, ultrasound was found to be diagnostic only 18% of the time.1 Ultrasound is also suboptimal for characterizing early-stage splenic infarcts because they are isoechoic with the splenic parenchyma.
A CT scan of the abdomen with intravenous contrast is the imaging modality of choice for infarct, as it is fast, sensitive, and specific. A CT scan accurately identifies splenic infarction and can reveal associated abnormalities in other organs. If infectious endocarditis is the causative factor, then additional occlusions may be noted in the hepatic or enteric vasculature.
Magnetic resonance imaging (MRI) is rarely the first choice of imaging, given the prolonged acquisition time compared with CT scan.
Initial workup should include a CBC, electrolytes, and blood cultures. Depending on the severity of the patient’s abdominal pain, imaging may start with a plain abdominal film, which is widely available, involves relatively low radiation exposure, and can reveal free intra-peritoneal air concerning for perforated viscus.
Ultrasound is sensitive in detecting the presence of a splenic abscess, but is nonspecific and does not provide the additional clinically relevant information, such as involvement of neighboring organs or the exact size and location of the abscess. The appearance of an abscess on ultrasound is variable, making this modality difficult for diagnostic confirmation.
As with splenic infarction, abdominal CT scan with IV contrast is the study of choice for splenic abscess, because it most accurately characterizes the number and location of abscess cavities, as well as the cavity contents. CT scan can reliably distinguish an abscess from similar-appearing disease processes, such as splenic cyst or hematoma.3
Evaluation of the patient with abdominal trauma begins with evaluation and support of the airway, breathing, and circulation. Laboratory studies in acute trauma are of limited diagnostic value, but lactate, hematocrit, and chemistry levels can provide helpful baselines to guide resuscitation. A portable chest film revealing left-sided rib fractures can implicate splenic injury, as can displacement or a corrugated appearance of the greater curvature of the stomach due to splenic hematoma infiltrating the gastrosplenic ligament.8
The focused assessment with sonography for trauma (FAST) examination has supplanted routine diagnostic peritoneal lavage for determination of hemoperitoneum. FAST in the hands of an experienced operator has a sensitivity of greater than 90% for detecting the presence of intra-peritoneal fluid.12 The test can be quickly performed at the bedside of even the most unstable patients. Hemodynamic instability with a positive FAST examination mandates exploratory laparotomy for hemorrhage control.
In hemodynamically stable patients, a CT scan with IV contrast best evaluates for splenic injury, as it visualizes abnormalities in the splenic parenchyma as well as intra-peritoneal blood. Patients with a negative FAST examination may not need a CT scan, but up to 29% of blunt trauma injuries may be missed if a FAST examination is the sole evaluation.13 Better access to CT scanners and decreased cost has increased the use of CT for diagnosing splenic injury from 59.1% in 1987 to 89.4% in 2001.14
MRI is seldom used in a trauma situation because of the long duration required for image acquisition. However, if a clinician desires follow-up of a splenic injury with cross-sectional imaging, MRI may be useful as it avoids ionizing radiation.