Films and Scans
Always eager to pick up another chart (now that we are on productivity-based reimbursement), you snatch the top case: a 68-year-old male with HTN and a regular primary care doctor. “Right sided chest and stomach pains for 4 days”, quips the triage note. “Unable to eat today, vomiting”. Sounds straight-forward, a likely admission to one of the few remaining local doctors still admitting their own patients to the hospital. An EKG performed per protocol at triage is on the chart: Normal. You ask the tech for a rapid-troponin and order a CXR as well as some “abdominal pain” labs. You peruse the vitals on the way to the room. P 70, BP 105/66, RR 22, sat 97% on RA. He takes Lopressor bid, perhaps preventing tachycardia of volume loss.
In the room you find the patient, along with his concerned wife. “He won’t eat anything today,” she reports. “He is just lying around.” You introduce yourself and sit on the bed. The patient does not like that, wincing in pain as you get comfortable. “This is killing me, Doc,” he says, “it just won’t go away.” He notes the RUQ region. A directed history reveals stomach pain rather than any chest discomfort. The abdominal pain has been on/off for a few days and persistent in the RUQ since yesterday. Exam confirms RUQ pain with some voluntary guarding. So far so good; possible gall bladder, admit, consult the surgeon, IV antibiotics and you are done.
Not so fast. You peek with the ultrasound for confirmation . . . and no gallstones. Worried that you might have missed something, you back-track in the H & P. Ultrasound shows no AAA or free-fluid and the vascular exam is normal. So is the cardiopulmonary exam. The gall bladder you see on US is slightly dilated and the patient appears to have a sonographic Murphy’s sign. Troponin and CXR are normal, other GI labs pending. The WBC is 11.4 with 78 segs – useless.This case still sounds like a hot gall-bladder to you. Sadly, it is after hours, and the ultrasound techs are home safely tucked in their beds for the night. You order a non-contrasted CT scan of the abdomen instead. What does it show?
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This case was not difficult clinically, but we might have been mislead by the negative ultrasound. Of course, acute cholecystitis will develop in the absence of gallstones, the so-called acalculous subtype. This classically presents in the elderly and diabetic patients, with more subacute symptoms. Ultrasound will show no stones, and often a dilated GB with thickened wall. On CT imaging, the gall bladder will show similar findings with the bonus of peri-cholecystic inflammation and stranding that ultrasound will not show. Although ultrasound is often thought of as the “classic” imaging approach to the gallbladder, newer generation CT scanning may be comparable for making the diagnosis of acute cholecystitis.
In this CT scan, you get great images due to the presence of intra-abdominal fat planes. Stranding shows up as thickened streaks in and around the affected organ (arrows), sometimes in conjunction with fluid. It is important to recognize that in a young person with minimal intra-abdominal fat, this stranding may be difficult or impossible to see.
Ultrasound is great for speed but CT saves the day again. There is a good argument to be made for using non-contrasted abdominal CT scanning as a “first study” to image the abdomen in the elderly patients with at least moderate severity stomach pains. Whereas plain abdominal X-rays will identify most perforation and obstruction, CT is superior for these problems. CT also images the solid organs well (even without contrast), and will often confirm other diagnoses (e.g. AAA, acute GB, diverticulitis, appendicitis and many others). With the newer 4th generation scanners, a non-contrasted CT is now almost faster than 4 plain films of the abdomen – you just need to remember to get a portable CXR with the study.
CT’s major drawback? Radiation exposure. A typical abdominal CT scan gives you about ten times the exposure of a set of plain films, increasing the risk of cancer. This increased cancer risk is most pronounced under age 20 years, and becomes negligible by age 50 years.
John Dallara practices Emergency Medicine in Virginia and North Carolina, and directs the Emergency Medicine PREP Course, www.emprepcourse.com