A 77-year old man presented to the emergency department with a complaint of appetite loss over the past 15 days. He reported ongoing symptoms for the past 5 months. However, over the previous 15 days, his appetite had been so poor that he only drank 1-2 nutrition drinks per day. He reported a 10-15 lbs weight loss paired with fatigue and weakness. He denied nausea, vomiting, abdominal pain, fevers, and chills. The patient reported normal bowel movements. He denied any significant medical history and had no records in our EMR. He reported an unremarkable colonoscopy 7-8 years ago.
Upon physical examination, he was non-toxic in appearance. Vitals were as follows:
BP: 155/89 | HR: 105 | RR: 16 | T: 99.8 F | Sp02 100% on RA |
The patient had no masses, no hepatomegaly, no flank pain, and no tenderness to the abdomen upon palpation. Laboratory evaluation included a CBC which was remarkable for an elevated white blood count of 23,200 with a left shift. The chemistry panel was notable for normal ALT, AST, bilirubin, and creatinine.
Bedside ultrasound was performed, and the following images were obtained. In examining these images, what do you notice and how would this change your patient management?
Answer and Learning Points
In the images above, a thickened gallbladder wall with “hole-signs” can be seen, indicating perforation.
Biliary pathology is the third most common cause of acute abdominal pain presenting to the ED . Unfortunately, labs and clinical exam findings, either alone or in combination, are insufficient to reliably rule out biliary pathology . Point-of-care ultrasound (POCUS) in the ED can detect cholelithiasis with a sensitivity and specificity of 89.8% and 88.0%, respectively . Regarding the detection of cholecystitis, ED POCUS features a sensitivity and specificity of 87% and 82%, respectively . In this case, we visualized a perforation and abscess outside the inflamed wall of the gallbladder, illustrating the accuracy and utility of POCUS as a diagnostic tool.
How to best visualize the gallbladder:
1. Subcostal sweep: With the marker dot to the patient’s head, place the probe in the subxiphoid/epigastric area. Next, slide the probe slowly to the patient’s right flank until the gallbladder is visualized or one has determined that another view is necessary.
2. Subcostal fanning: With the marker dot to the patient’s right, place the probe in the RUQ abdomen, where one would palpate for a non-ultrasound Murphy’s sign. Fan cephalad to look for the gallbladder in the area under the anterior ribs.
3. X-7: Start subxiphoid and move the probe approximately 7 cm to the patient’s right, scan in transverse orientation transverse below or through the ribs. If scanning through the ribs, one may need to rotate the probe slightly clockwise to align the probe with the intercostal space.
4. Mid-axillary longitudinal view: Obtain a view of Morrison's pouch as you would when completing a FAST (marker dot toward the patient’s head, patient supine, and probe placed in the mid axillary line). Remember, the kidney is retroperitoneal. After identifying the hepatorenal interface, slowly fan anteriorly until the gallbladder is directly under the probe. The common bile duct will be parallel and superficial to the portal vein. The inferior vena cava, with its characteristic respiratory variation, will be deep to the portal vein. Use color flow to differentiate the structures, as the common bile duct will not have color flow.
5. Roll the patient: If the above does not yield satisfactory views, roll the patient into a left lateral decubitus position. This will bring the gallbladder to a more anterior location and likely improve visualization of the GB when the steps above are repeated in this new patient position.
The upper limit of normal for the adult common bile duct is 6mm up to the age of 60. After this, the upper limit of normal rises an additional 1mm for every decade of life after 60 (e.g. 7mm at 70 years of age). Remember, there is a band of connective tissue called the main lobar fissure (MLF) that anchors both the portal triad and the neck of the gallbladder. Therefore, if you see the portal triad, you can then find the main lobar fissure emanating from the portal triad and track it to the neck of the gallbladder. The converse is true when locating the portal triad after identifying the gallbladder (follow the gallbladder neck, then trace the MLF to the portal triad).
During the examination, measure the thickness of the anterior gallbladder wall. The posterior wall is subject to posterior acoustic enhancement, which may yield an inaccurate measurement. A normal gallbladder wall thickness should measure less than 3 millimeters (mm). This measurement serves as a baseline for evaluating potential abnormalities.
Signs of Cholecystitis:
Cholecystitis can be diagnosed by observing gallbladder wall thickening greater than 3mm, pericholecystic fluid collection, gallbladder distension, and the presence of a sonographic Murphy's sign (positive when the point of maximal tenderness is identified by pressing the abdomen with the ultrasound probe while the gallbladder is centered on the screen) .
The presence of gallstones within the gallbladder lumen can be detected through ultrasound. Gallstones are typically visualized as rounded structures with an bright, anterior outer layer and associated acoustic shadowing (similar to bone). When the stones occupy most of the lumen of the gallbladder, or a gallbladder is contracted around one or more stones, one may appreciate a “Wall Echo Sign”, where the shadowing from the stones obstructs visualization of the posterior wall of the gallbladder. Note that non-calcified stones will not produce shadowing artifacts behind them.
The significance of sludge in ultrasound imaging of the gallbladder can vary depending on the clinical context. Sludge itself can be a precursor to the formation of gallstones. It may indicate an imbalance in the components of bile, such as excess cholesterol or insufficient bile salts, which can lead to the development of gallstones over time. Perforation can be diagnosed by observing gallbladder wall discontinuity or disruption, pericholecystic fluid collection or abscess formation, and signs of free fluid in the abdominal cavity .
POCUS is a powerful diagnostic modality for identifying biliary pathology, including cholecystitis, cholelithiasis, and perforation of the gallbladder wall. By following the scanning technique outlined above and identifying findings consistent with biliary pathology, clinicians can obtain accurate diagnoses and facilitate appropriate patient management. POCUS is a valuable tool to use in conjunction with a patient's clinical history, physical examination, and other diagnostic modalities to ensure comprehensive assessment and optimal healthcare outcomes.
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This post was written by Cameron , Ben Supat, MD, MPH, and Colleen Campbell, MD. Posted by Ben Supat, MD, MPH.