Ultrasound and subtle lab findings may convince you to admit that patient with RUQ pain.
It’s another hectic day in paradise when your resident asks if she can present a case to you. The patient is a 49-year-old female who presents to the ED for abdominal pain. The patient states that three days ago she had an episode of epigastric pain that came on suddenly, was bad for about an hour, and then gradually resolved over about three hours. Today it recurred, but is more severe, 9 out of 10, and radiates to the right upper quadrant. It has been present for over 10 hours and is getting no better. She states that she vomited once and has chills but doesn’t think she has had a fever. She took ibuprofen about an hour ago for the pain, noting that it hasn’t really helped. She denies any other complaints.
For her physical exam, your resident notes “stable” vital signs although the vitals have only been taken once. Pulse is 97, blood pressure is 93/61, respirations are 22, and temperature is 98.9. She is described to you as obese with right-upper-quadrant tenderness and a positive Murphy’s sign, but not other positive findings.
The PA in triage ordered labs about an hour and a half ago, and they are already resulted and show the following: WBC 5.7, hemoglobin 12.3, chemistry and LFTs all within normal limits. Your resident brings you the following images that she saved with her own bedside sonogram. She tells you her plan, “This looks like simple gallstones with no real red flags. Can we send her home with hydrocodone and arrange for a formal ultrasound and surgical consult as an outpatient?”
Q: Do you sign off on your resident’s management plan? What do the images show?
Do not sign off on this plan! Before we get to the images, there are indeed multiple red flags here. First, the duration of the pain: pain of a presumed biliary origin that lasts more than six hours is cholecystitis until proven otherwise, so formal imaging is indicated here (see the EM 1-minute consult on cholecystitis below for more clinical pearls and pitfalls). The second red flag is the vital signs: a pulse of 97 is under 100, but is a little on the high side and a blood pressure of 93/61 is probably not normal in a 49-year-old obese female with 9/10 pain, neither are respirations of 22, and a temperature of 98.9 an hour or two after ibuprofen could represent a fever, especially in a patient with chills.
The third red flag is the physical exam: a positive Murphy’s sign is an exam finding that has been described in cholecystitis, not biliary colic.
The labs are reassuring, but did you notice that the differential was not reported? This patient actually had 22 bands. Always wait for the results of the differential if one was ordered. A normal white count is usually reassuring, but in the setting of possible infection the differential includes severe sepsis. It is important to be aware that no single lab value is better than 50% sensitive for cholecystitis, and not infrequently all the labs will be normal.
The images show two transabdominal views of the gallbladder. The first shows a large gallstone with posterior shadowing that is possibly impacted in the gallbladder neck. To the right side of the image, near the gallbladder fundus, there is also shadowing but no evidence of stones. This could be due to an air collection from gallbladder rupture (see labeled ultrasound below). The second image above focuses on this area and shows a non-descript area with shadowing that is probably free air, consistent with a perforated gallbladder from cholecystitis.
A confirmatory CT scan (shown below) was requested by the surgical consult. Note the pericholecystic fluid but also the fluid collection medial to the posterior liver and lateral to the right kidney, as well as free air anterior and medial to the gallbladder.
The patient received IV ampicillin/sulbactam and was taken emergently to the operating room. Fortunately, she did well and followed up in the post-operative surgical clinic rather than in the septic-shock or ascending cholangitis clinic.
Pearls and Pitfalls: Gallbladder & RUQ Ultrasound
- Know Your Limits: 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 diagnoses and treatment of unstable patients. It can also decrease the use of CT scan and thereby minimize radiation exposure. However, you need to consider your skill level and know your limitations. When unsure, order a formal study. If your department has an ED dedicated ultrasound machine, it should consider implementing a quality improvement program that is approved by both ED administration and radiology.
- Finding the Gallbladder: Lying the patient on their left side and starting by locating the inferior liver edge can help.
- The Sonographic Murphy’s Sign: To check for a sonographic Murphy’s sign, which is a sign of cholecystitis, 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. False negatives may occasionally occur if the patient has received opiates prior to examination.
- The Gallbladder Wall: One sign of cholecystitis is a thickened gall-bladder wall. The normal gallbladder wall can be up to 3mm thick. The most common conditions other than cholecystitis that may cause thickening of the gallbladder wall include hepatitis, hypoalbuminemia, tumor, hyperplastic cholecystosis, adenomyomatosis, and CHF. In the absence of ascites, the presence of pericholecystic fluid, also supports the diagnosis of acute cholecystitis. If there is clinical uncertainty, a nuclear biliary scan (HIDA or DESIDA scan) may be performed.
- The Common Bile Duct: A dilated common bile duct is another sign of acute cholecystitis. The normal common bile duct inner diameter should be less than 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.
- The Gallbladder Contents: Look for a dilated gallbladder, evidence of stones, and for sludge. Gallstones should be mobile, unless they are impacted in the gallbladder neck, and should cast an acoustic shadow. If all stones are mobile in a patient who remains symptomatic, consider that they may be a red herring and not the true cause of the patient’s pain. Remember that approximately 15% of adults have asymptomatic gallstones. If there are no sonographic signs of cholecystitis, but a gallstone is impacted (non-mobile) in the gallbladder neck, be suspicious for early cholecystitis and consider admission, additional imaging, or at least next-day follow-up. Always also consider early cholecystitis when pain lasts for more than six hours, even when the ultrasound is normal except for the presence of a stone. Uncomplicated gallstone attacks usually should only last a few hours. Make sure to explain this to patients if you for some reason decide to send them home with opiates. Attacks lasting longer than that may be something more serious.
- Pitfalls: Don’t miss a single obstructing gallstone hidden in the gallbladder neck. It can sometimes be hard to see. Also, do not get faked out by an incidental “red herring” gallstone. As previously mentioned, many people have gallstones for years with no symptoms, so if everything does not fit clinically, look further for something else causing the abdominal, flank, or rib pain. Some examples include aortic aneurysm, Fitz-Hugh-Curtis syndrome, high appendicitis, PE, kidney stone, and pneumonia. Finally, don’t miss an AAA, even if it is also incidental, because you did not look for it. Ultrasound techs look. The aorta is not that far away, and should be checked routinely in anyone over the age of 50 who is having an abdominal ultrasound for another reason. Screening saves lives!