Soundings: Identifying gallstones

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Your next patient is a 28-year-old woman with the triage complaint of “Right-sided abdominal pain”. Also on the chart is the note “history of gallstones.” You head into the room and meet the patient.

Your next patient is a 28-year-old woman with the triage complaint of “Right-sided abdominal pain”. Also on the chart is the note “history of gallstones.” You head into the room and meet the patient.
altShe’s not 40, but she is fat and fertile with her husband and three children in tow. You count your lucky stars when you confirm that her pain is in the upper abdomen, and not the lower abdomen. That means you should be able to avoid both a pelvic exam and the long wait to get a “rule out appy” CT done and read by the off site night radiologist. Your patient tells you that she has been having intermittent epigastric and right-upper-quadrant abdominal pain for about six months. The pain usually lasts less than three hours, but not tonight. Sometimes antacids help, but when they don’t, she usually takes two Vicodin. Tonight the pain is in both areas, is worse than normal, and has lasted about six hours with only minimal relief from Maalox followed by Vicodin. She has also had six bouts of bilious emesis today and reports one loose stool earlier in the evening. She denies fever, jaundice, pruritus, trouble breathing, urinary complaints, or any other associated symptoms.
alt On exam, she is quite tender in the right upper quadrant as well as the epigastrium. She has a positive Murphy’s sign to boot. The rest of her exam is essentially normal except her tongue, which appears slightly dry. You order the routine labs including LFT’s, a pregnancy test, a UA and an ultrasound. You also order some Reglan and IV fluids, and since Maalox didn’t work at home, you go straight to fentanyl for analgesia. That way if she’s pain free at the end of your shift, you’ll know she’s actually improved and its not just the narcs. After dropping the orders off with the secretary, you get back into your dispo mode, trying to wrap things up with your other patients.
About 45 minutes later you receive your lab results. All are within normal limits. As you try to track down your ultrasound results, you discover that the tech had to be called in from home, and she lives over an hour from the hospital. You go back to recheck your patient. She’s still there, and hasn’t gone for imaging yet. You explain the delay to her and her family and ask how she is doing. She replies that her pain, which had been relieved by the fentanyl, has returned. This, at least, helps you formulate a plan. If you had used morphine, you might have masked things for a much longer period of time.
You think she’ll eventually need to be admitted for early cholecystitis despite the normal LFT’s and normal WBC count because her pain has lasted more than the magic 6 hours, but you’ll need at least an ultrasound to make a convincing argument to her PCP. Fortunately, that’s not a problem. You wheel over the ED’s new ultrasound machine so that you can take a look yourself.

See next page to learn more about the three images that you might obtain from the right-upper-quadrant. What does each show?


Image 1 shows acalculous cholecystitis.
The gallbladder wall is thickened beyond 3 millimeters, and instead of gallstones a layer of sludge is faintly visible in the dependent portion of the gallbladder. Bile within the gallbladder usually appears anechoid (black) on ultrasound, but sludge is somewhat echoic (gray). For extra credit, find the dilated common bile duct (unlabeled).
Image 2 shows an echoic (white) stone lodged in the gallbladder neck.
A dark acoustic shadow is seen below and behind the stone. To confirm that the stone is truly stuck, you could roll the patient on to her side. Mobile stones move under the force of gravity, impacted stones do not.
Image 3 demonstrates a patient with multiple very small gallstones.
The gallbladder lumen appears black, the wall on the left side looks nice and thin, but on the right side, what at first glance may look like a unilaterally thickened wall is actually a collection of many tiny stonelets. Only stones would form a shadow like this. Small stones are more likely to be passes into the common bile duct where they can cause an obstruction, and if they go further, pancreatitis as well.
Continue Next for Tips and Tricks
Tips and Tricks Using ultrasound to image the gallbladder
1. Know your limitations: Ultrasound may help clarify findings elicited by a thorough history and physical exam. When used correctly, it can greatly improve diagnostic accuracy, and help guide patient management, especially for time-critical diagnosis and treatment of unstable patients. If you use ultrasound in your ED, your department should have a quality improvement program set up that is approved by both ED administration and radiology.
2. Look for a dilated gallbladder, evidence of cholelithiasis or sludge, gallbladder wall thickening >3mm, peri-cholecystic fluid, bile duct dilatation, and a sonographic Murphy’s sign.
3. To check for a sonographic Murphy’s sign, place the ultrasound probe at the maximal point of tenderness in the right upper quadrant. If the probe is placing direct pressure on the gallbladder fundus, you have a positive sonographic Murphy’s sign.
4. Normal gallbladder wall thickness can be up to 3mm. The most common conditions other than cholecystitis that may cause thickening of the gallbladder wall include hepatitis, hypoalbuminemia, tumor, hyperplastic cholecystosis, adenomyomatosis, and CHF.
5. Normal common bile duct inner diameter should be under 4mm, but may be higher, up to 10mm, post-cholecystectomy. In addition the diameter may be higher in older patients, up to 1mm per decade of life.
6. Don’t miss a AAA because you didn’t look. It’s not that far away.
7. Don’t miss a single obstructing gallstone hidden in the gallbladder neck.
8. Polyps do not move upon patient repositioning, and usually do not cause acoustic shadows. Unimpacted gallstones should be mobile and will cause shadowing unless they are too small.
9. Gallbladder wall thickening may be noted on patients who are post-prandial and therefore have a contracted gallbladder. Look for other signs that may suggest cholecystitis.
10. Practice Makes Perfect: With bedside ultrasound there is no substitute for experience. The more ultrasounds you do, the better you will be able to differentiate abnormal from normal, even when you may not be sure exactly what the abnormality is. An image library of normal and abnormal ultrasounds helps immensely and can take you there. Check out the “Ultrasound Library” link on the left hand column of this page.


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