Case 34: Rare Cause of Knee Pain


A 58-year-old female presented with a chief complaint of focal lateral knee pain and swelling. She had a remote history of anterior cruciate ligament repair, as well as medial collateral ligament injury and meniscal injuries. The patient stated that she had a history of recurrent intermittent effusions. However, that day she noted focal swelling. She reported playing tennis a few days before and noted a pain in her knee with pivoting. No knee instability. No fever.


Vitals: BP 118/60 | Pulse 52 | Temp 97.8 °F (36.6 °C) | Resp 12


On physical examination of the knee, there was a 2 cm x 3 cm firm, immobile round mass at the inferior lateral aspect of the left knee with associated pain, mild warmth, and swelling. Decreased flexion of the joint was observed, with some pain beyond 100 degrees of flexion.



A bedside ultrasound was performed. What do you see?

Figure 1: Ultrasound of the lateral aspect of the knee joint

Figure 1: Ultrasound of the lateral aspect of the knee joint

Figure 2: Knee Effusion

Figure 2: Knee Effusion

Figure 3: Joint effusion and meniscal cysts

Figure 3: Joint effusion and meniscal cysts

Figure 4: Joint effusion

Figure 4: Joint effusion

Figure 5: MRI of anterior cyst forming on the meniscus

Figure 5: MRI of anterior cyst forming on the meniscus


In these images, we see classic findings of a parameniscal cyst. There is a joint effusion seen superior with Hoffa’s fat pad evident. In the lateral knee, we see extrusion of the meniscus on ultrasound, along with several small fluid collections within the meniscus (meniscal cysts). Beyond the margin of the meniscus, we see the larger parameniscal cyst situated more superficially and featuring a thick wall. Corresponding MRI images from a few months prior also show the anterior cyst forming on the meniscus. Meniscal cysts are found in 1% of MRIs obtained for knee pain [1]. They are a rare pathology most often associated with a synovial leak of fluid through degeneration of the meniscus, secondary to tears of the meniscus. Physical exam findings associated with meniscal cysts include localized pain, with a firm fluid collection at the joint line, anterior or posterior, often accompanied by a joint effusion. However, only 20% of cysts are palpable on examination with the average size being 1-2 cm [2]. Patients will present with local pain, but may also present with peroneal nerve palsy, or foot drop, if the cyst is located inferior and laterally. Point-of-care ultrasound confirms the diagnosis with an accuracy of 94%, a sensitivity of 97%, and a specificity of 86% [3]. The ultrasound appearance of the cyst may be multiloculated and contiguous with the knee joint along the meniscus or within the meniscus. The fluid removed from the cyst is often thick and gelatinous and therefore requires a large gauge needle and ultrasound guidance for successful aspiration [4]. A steroid injection is often performed following fluid aspiration. If there is recurrence, the cyst can be surgically removed. CT or MRI can also confirm diagnosis [5]. Point-of-care ultrasound is a useful tool to distinguish meniscal cysts from other cystic and solid masses at the knee joint [6]. The differential diagnosis of meniscal cysts includes osteophytes associated with degenerative joint disease, traumatic bursitis, lipoma, ganglion cyst, or, rarely, synovial sarcoma.


1) Anderson JJ, Connor GF, Helms CA. New observations on meniscal cysts. Skeletal Radiol. 2010 Dec;39(12):1187-91. doi: 10.1007/s00256-010-0993-2. Epub 2010 Jul 31. PMID: 20680623.

2)Crowell MS, Westrick RB, Fogarty BT. Cysts of the lateral meniscus. Int J Sports Phys Ther. 2013 Jun;8(3):340-8. PMID: 23772349; PMCID: PMC3679639.

3) Chang A. Imaging-guided treatment of meniscal cysts. HSS J. 2009 Feb;5(1):58-60. doi: 10.1007/s11420-008-9098-z. Epub 2008 Nov 7. PMID: 18989726; PMCID: PMC2642552.

4) Chen H. Diagnosis and treatment of a lateral meniscal cyst with musculoskeletal ultrasound. Case Rep Orthop. 2015;2015:432187. doi: 10.1155/2015/432187. Epub 2015 Feb 5. PMID: 25722908; PMCID: PMC4334430.

5) Lantz B, Singer KM. Meniscal cysts. Clin Sports Med. 1990 Jul;9(3):707-25. PMID: 2199079.

6) Rutten MJ, Collins JM, van Kampen A, Jager GJ. Meniscal cysts: detection with high-resolution sonography. AJR Am J Roentgenol. 1998 Aug;171(2):491-6. doi: 10.2214/ajr.171.2.9694482. PMID: 9694482.

This post was written by Skyler Sloane, Ben Supat MD MPH, and Colleen Campbell MD

Case 33: Parotid Mass

A 73-year-old male with a past medical history including atrial fibrillation and hypertension presented to the ED for admission for planned resection of a parotid mass with ENT. He first noted pain to his right cheek several months prior. Over this period, a mass was noted. The mass continued to grow over time, raising concern for malignancy, and the decision was made to pursue resection of the mass. On presentation, he endorsed significant pain to the right parotid area, but denied any fever, chills, chest pain, SOB, nausea, vomiting, abdominal pain, or dysuria. On physical exam, gross observation revealed diffuse swelling of the patient’s right cheek just anterior to the right tragus with marked tenderness to palpation. The remainder of his exam was unremarkable.

BP 160/81 | Pulse 75  | Temp 97.4 °F (36.3 °C)  | Resp 20  | Ht 5' 11" (1.803 m)  | Wt 87.7 kg (193 lb 5.5 oz)  | SpO2 98%  | BMI 26.97 kg/m²

Point of care ultrasound was performed to visualize the mass (right side) and compare it to the contralateral, non-diseased glandular tissue (left side). The following scans were obtained:


Figure 1: Left parotid, transverse view

Figure 1: Left parotid, transverse view

Figure 2: Left parotid, sagittal view

Figure 2: Left parotid, sagittal view

Figure 3: Right parotid with mass, transverse view

Figure 3: Right parotid with mass, transverse view

Figure 4: Right parotid with mass, sagittal view

Figure 4: Right parotid with mass, sagittal view




The parotid gland can often be elusive on account of its relatively unremarkable echogenicity. However, using anatomical landmarks, finding the gland and its surrounding structures can be quick and easy. The technique used for obtaining our bedside images for this case is summarized below: 

Figure 5: Scan plane used to obtain sagittal view of the parotid

Figure 5: Scan plane used to obtain sagittal view of the parotid

Figure 6: Scan plane used to obtain transverse view of the parotid

Figure 6: Scan plane used to obtain transverse view of the parotid

Figure 7: Labeled Anatomy of Parotid Gland (image from

Figure 7: Labeled Anatomy of Parotid Gland (image from

The superficial location of the parotid necessitates a high-resolution linear probe for optimal scan resolution. We found that the base of the tragus was an easy and reliable landmark to use as a starting waypoint for obtaining either the transverse or sagittal plane views. This positioning allows for identification of the parotid gland as it wraps around the angle of the mandible. The transverse plane is particularly useful for visualization of the accessory parotid gland, which is known to be the landmark for the parotid (Stenson’s) duct.2,3 In fact, ultrasound has been shown to successfully diagnose parotid duct obstruction.The sagittal plane can be useful when searching for an optimal cross-section of Stenson’s duct, especially when it is dilated (e.g. in the case of an obstructing stone). Should the duct prove difficult to locate, the course and angle of Stenson’s duct may be approximated by drawing an imaginary line from the base of the tragus to the upper lip.5 Though we were unable to obtain optimal imaging of Stenson’s duct with this patient, we were able successfully locate the accessory parotid gland using the technique described above.

Figure 8: Left parotid gland (PG) with labeled accessory lobe (AL) noted to be just medial and separate from the main gland in the transverse plane

Figure 8: Left parotid gland (PG) with labeled accessory lobe (AL) noted to be just medial and separate from the main gland in the transverse plane

Overall, this case was an excellent exercise in using anatomical landmarks for localization of the parotid gland, review of notable anatomy, and comparison with diseased tissue. This patient underwent successful right superficial parotidectomy in the following days and was discharged on post-op day 1. The pathology report was concerning for high grade carcinoma with localized spread but clean margins. No lymph node involvement.


1. The parotid gland. TeachMeAnatomy. (n.d.).

2. Parotid gland- normal. ULTRASOUNDPAEDIA. (n.d.)

3. Human Anatomy Lessons. (2022, August 5). Parotid gland. Learn Human Anatomy.

4. Goncalves, M., Mantsopoulos, K., Schapher, M., Iro, H., & Koch, M. (2021). Ultrasound in the diagnosis of parotid duct obstruction not caused by sialolithiasis: diagnostic value in reference to direct visualization with sialendoscopy. Dentomaxillofacial Radiology, 50(3), 20200261.

5. Jones J, Howden W, Yu Y, et al. Parotid gland. Reference article, (Accessed on 21 Sep 2023)

This post was written by Henry Horita, Lainey Yu, MD, Ben Supat, MD, MPH, and Sukh Singh, MD. Posted by Ben Supat, MD, MPH.

Case 32: Perforated Gallbladder


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. 




(Ref range: 4.0 - 10.0 1000/mm^3)

ANC- Manual mode


(Ref range: 1.6 - 7.0 1000/mm^3)

Absolute monocytes


(Ref range: 0.2 - 0.8 1000/mm^3)



(Ref range: 0-41 U/L)



(Ref range: 0-40 U/L)



(Ref range: <1.2 mg/dL)



(Ref range: 0.67-1.17 mg/dL)

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?


Figure 1: Thickened gallbladder wall and echoic sludge surrounding a large gallstone. Gallbladder wall perforations can be seen at 2 o’clock and 11 o’clock.
Figure 2: Increased color flow indicative of inflammation.



Answer and Learning Points

Figure 3: Thickened gallbladder wall and echoic sludge around the cholelithiasis. Gallbladder wall perforation can be visualized at the 2 o’clock position.

Figure 3: Thickened gallbladder wall and echoic sludge around the cholelithiasis. Gallbladder wall perforation can be visualized at the 2 o’clock position.

Figure 4: Gallbladder wall perforation visualized at the 11 o’clock position.

Figure 4: Gallbladder wall perforation visualized at the 11 o’clock position.

Figure 5: CT image demonstrating gallbladder wall perforation at the 2 o’clock position as well as pericholecystic fluid.

Figure 5: CT image demonstrating gallbladder wall perforation at the 2 o’clock position as well as pericholecystic fluid.

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 [1]. Unfortunately, labs and clinical exam findings, either alone or in combination, are insufficient to reliably rule out biliary pathology [2]. Point-of-care ultrasound (POCUS) in the ED can detect cholelithiasis with a sensitivity and specificity of 89.8% and 88.0%, respectively [3]. Regarding the detection of cholecystitis, ED POCUS features a sensitivity and specificity of  87% and 82%, respectively [4]. 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.

Normal Findings:

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) [5].

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 [6].

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.



1) Cervellin, Gianfranco, Riccardo Mora, Andrea Ticinesi, Tiziana Meschi, Ivan Comelli, Fausto Catena, and Giuseppe Lippi. 2016. “Epidemiology and Outcomes of Acute Abdominal Pain in a Large Urban Emergency Department: Retrospective Analysis of 5,340 Cases.” Annals of Translational Medicine 4 (19): 362.

2) Trowbridge, Robert L., Nicole K. Rutkowski, and Kaveh G. Shojania. 2003. “Does This Patient Have Acute Cholecystitis?” JAMA: The Journal of the American Medical Association 289 (1): 80–86.

3) Ross, Marshall, Michael Brown, Kyle McLaughlin, Paul Atkinson, Jenny Thompson, Susan Powelson, Steve Clark, and Eddy Lang. 2011. “Emergency Physician-Performed Ultrasound to Diagnose Cholelithiasis: A Systematic Review.” Academic Emergency Medicine: Official Journal of the Society for Academic Emergency Medicine 18 (3): 227–35.

4) Summers, Shane M., William Scruggs, Michael D. Menchine, Shadi Lahham, Craig Anderson, Omar Amr, Shahram Lotfipour, Seric S. Cusick, and J. Christian Fox. 2010. “A Prospective Evaluation of Emergency Department Bedside Ultrasonography for the Detection of Acute Cholecystitis.” Annals of Emergency Medicine 56 (2): 114–22.

5) Simeone, J. F., J. A. Brink, P. R. Mueller, C. Compton, P. F. Hahn, S. Saini, S. G. Silverman, G. Tung, and J. T. Ferrucci. 1989. “The Sonographic Diagnosis of Acute Gangrenous Cholecystitis: Importance of the Murphy Sign.” AJR. American Journal of Roentgenology 152 (2): 289–90.

6) Sood BP, Kalra N, Gupta S, et al. Role of sonography in the diagnosis of gallbladder perforation. J Clin Ultrasound. 2002;30(5):270-274. doi:10.1002/jcu.10071

This post was written by Cameron Olandt, Ben Supat, MD, MPH, and Colleen Campbell, MD. Posted by Ben Supat, MD, MPH.

Case 31: A Man with Shortness of Breath

A 77-year-old patient presented to a rural Emergency Department with a chief complaint of shortness of breath a day prior to presentation. Patient also reported that he fell several weeks ago and hurt his ribs. He was subsequently admitted to the hospital and was ultimately treated for pyelonephritis. He endorsed being more sedentary than usual for the next several weeks. On the day of presentation he was lying in bed when he began to suddenly feel short of breath. He denied feeling any chest pain, lightheadedness, dizziness, nausea, vomiting, diarrhea, diaphoresis, jaw or arm pain. His shortness of breath had self resolved prior to coming into the emergency department. On physical examination, the patient was alert and had mild respiratory distress. He was tachycardic and also found to have inspiratory crackles in the right lower lung fields. The remainder of the physical exam was within normal limits.


Upon arrival, vitals were as follows:

BP: 92/70 | HR: 118 | RR: 18 | T: 98.2 | Sp02: 80’s% on RA to 90% with 15L NRB


Point of care ultrasound was performed and the following images were obtained. In these images, what do you notice and how does this change your patient management?


Figure 1: Parasternal Short Axis view of the left ventricle at the mid-papillary level

Figure 1: Parasternal Short Axis view of the left ventricle at the mid-papillary level

Figure 2: A normal parasternal Short Axis view of the left ventricle at the mitral valve level.

Figure 2: A normal parasternal Short Axis view of the left ventricle at the mitral valve level.

Figure 3: Our patient’s Parasternal Short Axis view of the D-sign in the left ventricle.

Figure 3: Our patient’s Parasternal Short Axis view of the D-sign in the left ventricle.

View shown in the image above is the parasternal short axis. To perform this technique, use the phased array transducer and place it around the 4th intercostal space, next to the sternum, with the probe marker to the patient’s right shoulder. For example:

Figure 4: Placement of probe for Parasternal Long Axis view [1].

Figure 4: Placement of probe for Parasternal Long Axis view [1].

Figure 5: Standard long axis view of the left ventricle at the mitral level [2].

Figure 5: Standard long axis view of the left ventricle at the mitral level [2].


Clockwise rotation of the probe (90 degrees) where the indicator is pointing towards the patient's left shoulder will provide a short axis view of the left ventricle. Normal parasternal short axis view in a patient without cardiac dysfunction will include the right ventricle sitting as a semi-circle on top of the circular left ventricle. For example: 

Figure 6: Placement of probe for Parasternal Short Axis view [1].

Figure 6: Placement of probe for Parasternal Short Axis view [1].

Figure 7: Standard short axis view of the left ventricle at the mitral level [2].

Figure 7: Standard short axis view of the left ventricle at the mitral level [2].

In our case, the right ventricle is pushing down on the left ventricle, indicating increased right sided pressures. This is the classic “D-sign” of the left ventricle, the septum has become straight due to the right sided pressures. 

Classically, the apical four view is used to diagnose elevated right sided pressures by comparing chamber sizes. However, this view can be challenging at times. In our case, we show the effectiveness of diagnosing right sided pressures using a parasternal short axis view [Figure 3].


We typically observe indications of increased pressures in the pulmonary artery and strain on the right side of the heart. These indications can be identified through the presence of reduced movement in the right ventricular wall, enlargement of the right ventricle and right atrium, abnormal motion of the septum during systole, and a dilated inferior vena cava that does not collapse during respiration.

In our case, POCUS utilizing the parasternal short axis view of the heart indicated the “D-sign”. In a normal heart with proper physiological functioning, the pressure in the left ventricle is higher than the pressure in the right ventricle. As a result, during systole the left ventricle maintains a round shape, causing the intraventricular septum to bulge into the right ventricle. However, if the right ventricle pressures are elevated, the septum becomes straight, changing the shape of the left ventricle into a "D".

 Case Conclusion

Visualization of the D sign led to a high concern for pulmonary embolism. Management of the patient’s hypotension was transitioned from fluid resuscitation to vasopressors, on which he was stabilized. He was then taken for a STAT CTA, showing a large saddle pulmonary embolus. The patient was treated with thrombolytics, and he was transferred to a tertiary care center for higher level of care. There, the patient underwent thrombectomy with removal of significant clot burden as below:

Figure 8: Clots retrieved post-thrombectomy.

Figure 8: Clots retrieved post-thrombectomy.

His clinical status continued to improve and he was discharged on hospital day 7 with no residual complications. 


In this case, recognition of the D-sign allowed for prompt and effective management of a critically ill patient, and the patient made a full recovery. Key clinical advantages were expediting a difficult diagnosis in a patient who was reportedly asymptomatic at the time of presentation, a rapid transition from fluid resuscitation (which could have worsened his right heart strain) to vasopressor support, and early imaging and thrombolytics before his clinical picture could worsen.


1) Lee V, Dinh V, Ahn J, Deschamps J, Genoba S, Lang A, Tooma D, White S, Krause R. Cardiac Ultrasound (Echocardiography) Made Easy: Step-By-Step Guide. POCUS 101. (Accessed May 30, 2023)

2) “Normal Cardiac Anatomy.” n.d. TPA. Accessed August 1, 2023.

This post was written by Cameron Olandt, Dr. Daniel Brownstein, Dr. Andrew Lafree, Dr. Colleen Campbell, and Dr. Sukhdeep Singh. Posted by Dr. Ben Supat.

Case 30: Ultrasound-Guided Extraction of a Foreign Body

A 53-year-old homeless alcoholic female presented to the emergency department with a chief complaint of localized left lower quadrant abdominal pain secondary to a possible gunshot wound. She was unclear but stated she thinks some boys in a gang fired at her two days prior with a possible BB gun. Pertinent medical history included psychiatric history, morbid obesity (BMI>40), chronic alcohol abuse, sepsis and hypoxemic respiratory failure. The patient was clinically intoxicated upon arrival and therefore history was of limited accuracy. 


Upon arrival, patient appeared stable and vitals were as follows:

BP: 121/63 | HR: 73 | RR: 18 | T: 98.4 | Sp02: 98% on RA 


Physical examination revealed a 10x10 cm area of ecchymosis with a central penetrating wound about 2mm, to the left lower quadrant. The patient was tender to palpation around the affected area but there was no significant warmth or erythema to suggest infection. No palpable foreign bodies were identified. There were no signs of peritonitis: the remainder of the abdominal examination was benign and patient had active bowel sounds. She denied vomiting, hematuria, hematochezia, and melena. She also denied shortness of breath, chest pain, and back pain.  


To evaluate the wound for the presence of foreign bodies and for depth of penetration, bedside ultrasound was obtained. What do you see, and how would this change your patient management?


Figure 1: Wound prior to foreign body exploration.

Figure 1: Wound prior to foreign body exploration.

Figure 2: A hyperechoic object with reverberation artifacts and shadow seen at 1cm.

Figure 2: A hyperechoic object with reverberation artifacts and shadow seen at 1cm.

Figure 3: Removal of FB under US guidance using curved hemostats.

Figure 3: Removal of FB under US guidance using curved hemostats.

Figure 4: Extracted pellet.

Figure 4: Extracted pellet.

Answer and Learning Points


Figure 4: Labeled ultrasound image shows hyperechoic object and reverberation artifact with shadow.


In these scans, an echogenic foreign body can be observed 1 cm below the epidermis with associated reverberation and mirror artifact. Using ultrasound guidance, a curved hemostat was used to remove the foreign body after local anesthetic injection. Upon contact with the forceps, the foreign body can be seen fluctuating in position. A rounded edge on the foreign body can be seen on the image.  Importantly, we clearly identified the peritoneal line to be > 4cm deeper than the foreign body and were able to safely determine the foreign body location to be significantly more superficial to the abdominal wall musculature. 


Soft tissue foreign bodies (FB’s) are a common reason for Emergency Department visits, with open wounds producing 4,171,000 visits to United States Emergency Departments in 2020 [1]. However, retained foreign bodies account for 7-15% of cases, particularly those involving the extremities. A granulomatous tissue response commonly known as an FB reaction results as the immune system attempts to isolate the FB from the host [2]. This can lead to serious adverse complications including soft tissue inflammation and infection. The most commonly retained FB materials are metal, glass and wood. Glass accounts for half of missed FB’s on physical examination and radiographs. Although essential, a physician-performed clinical history, physical examination, and wound exploration are not sufficient to exclude a FB from differentials [2]. Thus, imaging plays an essential role in improving patient outcomes that present with FB’s. 


MRI is not a suitable imaging modality, as metallic contents may have hazardous movements due to the magnetic field. Computed tomography (CT) and ultrasound sonography (US) are the most effective imaging modalities. CT and US have similar sensitivity in identifying high-density objects such as stone, metal and glass [3]. Low-density foreign objects such as plastic and wood are remarkably difficult to see in techniques other than US, regardless of superficial or deep impaction. For example, radiographic images have a sensitivity of 7.4% for wood [3,4]. Sensitivity of ultrasound for FB is 80% on average, and it carries a specificity of 85%, with metals being much higher due to noticeable reverberation, and wood is more difficult to detect. However, the sensitivity of US to identify foreign bodies in soft tissues begins to decrease as the depth of the foreign body surpasses 4cm [4]. 


US provides a unique advantage to foreign body detection as it can provide instantaneous and simultaneous visualization of foreign bodies during extraction procedures with minimal risk and no exposure to radiation. In a study of pediatric patients presenting with an FB, sonography performed by EM physicians provided an overall sensitivity of 67% and a specificity of 96.6% [4]. US is inexpensive and provides real-time visualization, however the quality of US images is operator dependent [5].


Material of FB  

Ultrasound finding


Hyperechoic area with pronounced acoustic shadow


Hyperechoic area with reverberation artifacts


Hyperechoic area with comet tails; less visible than metal


Hyperechoic area with slight acoustic shadow


Hypoechoic area with “halo” 

Table 1: A List of FB Materials and the Expected US Findings [3].


To perform this technique, scan use the linear probe in the area of the suspected location of the FB.  The FB can be identified by characteristic reverberation or acoustic shadowing, with additional indications being signs of infection, edema, or interruption of the fascial planes. Position the probe so that the FB is visualized in the center of the screen, and mark this area with a surgical pen. Rotate the probe 90 degrees and ensure the FB is in the middle of the US screen. Then mark this area with a surgical pen. Where these markings cross should give you the exact location of the FB such that incision and probing with forceps will result in effective removal of the FB. 


Removing foreign bodies is one of the least favorite procedures in the Emergency Department due to it’s difficulty and low success rates.  Bedside ultrasound is easily performed and is a useful adjunct in the accurate identification of foreign bodies and also can provide real-time guidance in foreign body removal.


1) Cairns C, Kang K. National Hospital Ambulatory Medical Care Survey: 2020 emergency department summary tables. DOI:

2) Carneiro BC, Cruz IAN, Chemin RN, et al. Multimodality Imaging of Foreign Bodies: New Insights into Old Challenges. Radiographics. 2020;40(7):1965-1986. doi:10.1148/rg.2020200061

3) Haghnegahdar A, Shakibafard A, Khosravifard N. Comparison between Computed Tomography and Ultrasonography in Detecting Foreign Bodies Regarding Their Composition and Depth: An In Vitro Study. J Dent (Shiraz). 2016;17(3):177-184.

4) Davis J, Czerniski B, Au A, Adhikari S, Farrell I, Fields JM. Diagnostic Accuracy of Ultrasonography in Retained Soft Tissue Foreign Bodies: A Systematic Review and Meta-analysis. Acad Emerg Med. 2015;22(7):777-787. doi:10.1111/acem.12714

5) Rupert J, Honeycutt JD, Odom MR. Foreign Bodies in the Skin: Evaluation and Management. Am Fam Physician. 2020;101(12):740-747.

This post was written by Cameron Olandt, Rachna Subramony, MD, Skyler Sloane, and Colleen Campbell, MD.

Case 29: Perforated Diverticulitis

A 37-year-old female presented to the emergency room with severe, radiating bilateral flank pain lasting one week. Pain was constant and pressure-like. Patient had a past medical history significant for constipation, ovarian cysts, diverticulitis, and a colonic polypectomy. She denied fever, vomiting, and denied melena and hematochezia. Patient had no dysuria, frequency or hematuria. She denied vaginal discharge or odor. Patient was seen and treated by her primary care provider with ciprofloxacin and metronidazole for presumed diverticulitis. When pain failed to improve two days later, patient presented to the Emergency Department.

Upon arrival, her vital signs were as follows:

T 98.2 | BP 109/73 | HR 71 | RR 16 | SPO2 99% on RA |

Her physical exam revealed left paraumbilical and left lower-quadrant tenderness. No masses were palpated. A bedside ultrasound of the abdomen is performed, and the following images were obtained. In examining these images, what do you notice and how would this change your patient management?

Diverticulitis itop GIF
Diverticulitis cropped view itop GIF

Answer and Learning Points


In these images/videos, a thickened bowel wall is observed in the distal descending colon and proximal sigmoid. Extensive pericolonic fat stranding is represented by the hyperechoic fat deep to the bowel, with no drainable abscess found.

In the emergency setting, computed tomography (CT) scans are highly accurate and remain the most widely used modality to diagnose diverticulitis, with an overall accuracy of 99% [1]. CT can assist in planning if surgical intervention is needed. An estimated 15-20% of all patients admitted with either complicated or uncomplicated diverticulitis will require surgical intervention during their initial admission, yet that likelihood increases to upwards of 50% for those with complicated diverticulitis [2]. However, concerns of radiation exposure and extended length of stays have led to increased use of point-of-care ultrasound (POCUS) [3].

Cohen et al found that POCUS performed by ultrasonographic-trained emergency physicians, physician assistants, and ultrasonographic fellows had both high sensitivity (92%) and specificity (97%) for diagnosing acute diverticulitis [3]. However, the usage of POCUS for diverticulitis by EM physicians is a new application and not a current widespread practice.


There are 3 POCUS indicators of acute diverticulitis, namely:

1) Thickened bowel wall greater than 5mm surrounding an adjacent diverticulum

2) enhancement of surrounding pericolonic fat

3) sonographic tenderness to palpation [3]


To perform this technique, place the curvilinear probe on the patient in the areas of tenderness and compress the bowel wall. The bowel will be found just deep to the peritoneal line. In diverticulitis, the bowel will appear with a thickened wall >4 mm with a visible diverticulum.

Surrounding hypoechoic edema is often visible. Perforation may appear contiguously to the diverticulitis. Normal bowel will compress fully with the ultrasound probe.


CT Image


This patient received a CT that confirmed acute flare of diverticulitis with contained perforation involving a short segment in the distal descending colon and proximal sigmoid, with no drainable abscess at this time. She was admitted to medicine with GI and surgery consults following.


1) Sai, V. F., Velayos, F., Neuhaus, J., & Westphalen, A. C. (2012). Colonoscopy after CT diagnosis of diverticulitis to exclude colon cancer: a systematic literature review. Radiology, 263(2), 383–390.

2) Wieghard N, Geltzeiler CB, Tsikitis VL. Trends in the surgical management of diverticulitis. Ann Gastroenterol. 2015;28(1):25-30.

3) Cohen, A., Li, T., Stankard, B., & Nelson, M. (2020). A Prospective Evaluation of Point-of-Care Ultrasonographic Diagnosis of Diverticulitis in the Emergency Department. Annals of emergency medicine, 76(6), 757–766.

This post was written by Cameron Olandt and Colleen Campbell MD RDMS.

Case 28: Nah-bscess

A 35 year old male with a history of IV drug use and HIV on ART presents to the emergency department with pain and redness of his left upper extremity for a few days. He denies systemic symptoms or prior history of abscess.

Vitals: Temp 98.5, HR 93,  BP 122/75, RR20

Physical Exam: Notable for a large, well circumscribed area of induration, erythema, warmth, and  tenderness on the left upper arm. Distal to the lesion, there is intact cap refill and 2+ radial pulse.

A bedside ultrasound was performed. What do you see?


cobblestoning and fluid collection
turbulent flow within fluid collection
pulsatile flow
continuous flow
continuous lumen

Answer and Learning Points


Image 1 is a transverse view of the LUE and demonstrates cobblestoning in the subcutaneous tissue which is suggestive of cellulitis. There is no fluid tracking on the fascial planes, fascial thickening, hyperechoic gas or dirty shadowing to suggest necrotizing fasciitis.

Image 1 also demonstrates a well-circumscribed, anechoic fluid collection concerning for an abscess. However, the lumen-like and well-demarcated appearance deep to the area of cobblestoning also suggests a blood vessel, and so we imaged it with color and pulse-wave doppler.

Image 2 use color doppler and demonstrates turbulent flow within the fluid collection. Superficial and medial to the fluid collection, a vessel can be appreciated with flow towards the ultrasound probe.

Image 3 and 4 use pulse wave doppler and demonstrate areas of both pulsatile and continuous flow in various parts of this structure.

Image 5 demonstrates continuity between a distal pulsatile vessel and the proximal fluid collection. The fluid collection likely represents an arterial aneurysm or arteriovenous fistula, as opposed to an abscess. Taking into consideration the patients history of IV drug use, trauma from repeated injections may have created abnormal structures within the patient’s vasculature.

Conclusion and Learning Points:

1. When there is concern for cellulitis, POCUS is a useful tool to quickly evaluate for drainable fluid collections, as well as to evaluate for necrotizing fasciitis.

2. When evaluating a possible abscess, it is important to confirm that the collection has no pusatility or flow before attempting drainage.


1. Bystritsky R, Chambers H. Cellulitis and Soft Tissue Infections. Ann Intern Med. 2018 Feb 6;168(3):ITC17-ITC32. doi: 10.7326/AITC201802060. Erratum in: Ann Intern Med. 2020 May 19;172(10):708. PMID: 29404597.

2. Paz Maya S, Dualde Beltrán D, Lemercier P, Leiva-Salinas C. Necrotizing fasciitis: an urgent diagnosis. Skeletal Radiol. 2014 May;43(5):577-89. doi: 10.1007/s00256-013-1813-2. Epub 2014 Jan 29. PMID: 24469151.

This post was written by Jeff Hendel, MS4 and Ben Liotta, MD, with further editing by Sukh Singh, MD.

Case 27: Ectopic Pregnancy

A 43 year old female with no past medical history presents to the Emergency Department (ED) with lower abdominal pain for the last three hours. She says she knows she is pregnant from a home pregnancy test, but has not had any appointment with obstetrics and has not had an ultrasound yet. She denies any vaginal bleeding.  

Vitals: BP 120/65 mmHg, HR 85, O2 100% on RA.

She is comfortable appearing, her abdominal exam shows mild tenderness to palpation diffusely in the lower abdomen with no rebound and her pelvic exam shows a closed os with no bleeding.

Her point-of-care urine pregnancy test is positive.

You perform a trans-abdominal bedside ultrasound, what do you see?  What are your next steps?

pelvic free fluid
positive fast

Answer and Learning Points


The first image is a transverse view of the uterus that shows free fluid in the retcouterine pouch (Pouch of Douglas). The second image is another transverse view of the uterus that also shows free fluid in the rectouterine pouch and then fans through to scan the uterus and adnexa. From what we see there is no gestational sac in the uterus and if you look closely there appears to be a heterogenous structure in the left adnexa. The final view is a FAST view in the right upper quadrant, looking at Morrison's Pouch. We see free fluid here as well. 

These findings - a positive pregnancy test, free fluid in the pelvis and no clear intra-uterine pregnancy indicates an ectopic pregnacny until proven otherwise. The next step should be a tranvaginal ultrasound and consultation with Gynecology. 

Conclusion and Learning Points:

The transvaginal ultrasound revealed a left-sided ectopic pregnancy, as seen in the following picture. They identified a fetal pole and even a fetal heart rate in the ectopic pregnancy. The patient was taken to the operating room with Gynecology and had a salpingectomy without complications. She was discharged home three days later. 

Learning Points:

    • Any female of child-bearing age with abdominal pain should be considered for ectopic pregnancy
    • Ultrasound findings in ectopic pregnancy will not always show the ectopic itself, but rather findings suggestive of ectopic:
      • Intra-abdominal free fluid
      • No clear intra-uterine pregnancy (patients with ectopic will sometimes still have a "pseudo-gestational sac" that appears similar to a gestational sac, but there will be no yolk sac or fetal pole)
      • Heterogenous adnexal structure
    • You should not wait for B-HCG measurements to consider ectopic pregnancy, case reports have shown ectopic pregnancies with minimal HCG levels can still rupture (1)


1. Fu, Joyce, et al. Rupture of ectopic pregnancy with minimally detectable beta-human chorionic gonadotropin levels: a report of 2 cases. J Reprod Med. 2007 Jun;52(6):541-2.

This post was written by Charles Murchison MD and Anthony Medak MD, with further editing by Amir Aminlari MD.

Case 26: Genicular Nerve Block for Knee Pain – A Novel Technique

A 68 year old female with no significant past medical history presents to the Emergency Department (ED) with one day of right knee pain after falling off her bicycle onto her right side. She was immediately unable to bear weight on her right leg. 


Vitals: T 98.3, HR 73, RR 18, BP 114/70, SpO2 99%


Right leg exam: mild right knee effusion. No ligamentous laxity. Tenderness to palpation over lateral joint line > medial joint line. Tenderness to palpation over proximal anterior tibia. Knee extension limited due to pain. Neurovascularly intact with soft compartments.


Radiographic imaging demonstrated an isolated right tibial plateau fracture depression of the lateral plateau. The patient reports she is in severe pain but dislikes taking both over-the-counter and opioid pain medications. 

What nerves may be targeted to provide pain relief to her knee while maintaining motor function? What anatomic landmarks should be used on ultrasound to identify the branches of this nerve?

Answer and Learning Points

The genicular nerves derive from various major lower extremity nerve branches (femoral, obturator, sciatic, tibial) nerves and provide sensation to the knee capsule and joint. Cadaveric studies suggest that most genicular nerves are easily identifiable landmarks that may be used for therapeutic purposes. 5  Genicular nerve blocks (GNB) are traditionally used in this setting of chronic osteoarthritis knee pain via radiofrequency ablation or perioperative knee pain via ultrasound (1-4, 9).

The use of a GNBs in the ED is a novel technique to provide motor-sparing, pain relief for acute knee pain. This 68 year old patient with an isolated lateral tibial plateau fracture reported 4/10 pain over her proximal tibia at rest and 8/10 over her proximal tibia with movement. Written informed consent was obtained for GNBs of her right knee. Anatomic landmarks for the superior lateral (Image A,B) , superior medial (Image C,D), and inferior medial (Image D,E,F) genicular nerves were identified on ultrasound.

genicular nerve block

genicular nerve block

genicular nerve block

The ultrasound probe was placed in the sagittal orientation for each site. The superior lateral genicular nerve was located on ultrasound at the junction of the lateral femoral epicondyle and the epiphysis of the shaft of the femur, adjacent to the superior lateral genicular artery (Image A,B). The superior medial genicular nerve (SMGN) can be identified on ultrasound at the junction of the medial femoral epicondyle and the epiphysis of the shaft of the femur, adjacent to the superior medial genicular artery (Image C, D). The inferior medial genicular nerve (IMGN) can be identified on ultrasound at the junction of the medial tibial epicondyle and the epiphysis of the shaft of the tibia, adjacent to the inferior medial genicular artery (Image E, F, G) (6-8).

Under ultrasound guidance and using sterile technique, the skin was first anesthetized with 1% lidocaine after each site. A 21-gauge, 2 inch echogenic needle was inserted percutaneously and advanced under ultrasound guidance using an out-of-plate technique to inject 1.5 mL of 0.5% bupivacaine around the right superior lateral, superior medial, and inferior medial genicular nerves. 

Learning points

    • Genicular nerves derive from several lower extremity nerves and supply sensory innervation to the knee. 
    • The superior lateral, superior medial, and inferior medial genicular nerves are commonly targeted for pain relief with chronic knee osteoarthritis and postoperative pain.
    • The SLGN, SMGN, IMGN are easily located on ultrasound using anatomic landmarks (junction between epicondyles and epiphysis of the femur and tibia, adjacent to paired genicular arteries).
    • To obtain the images, you can use the linear probe in the sagittal location over lateral femoral epicondyle, medial femoral epicondyle, and medial tibial epicondyle.


1. Ahmed, Arif. “Ultrasound-guided radiofrequency ablation of genicular nerves of knee for relief of intractable pain from knee osteoarthritis: a case series.” British Journal of Pain, vol. 12, no. 3, 2017, pp. 145-154, Accessed 18 November 2020.

2. Caldwell, George L. “Reduced Opioid Use After Surgeon-Administered Genicular Nerve Block for Anterior Cruciate Ligament Reconstruction in Adults and Adolescents.” HSS Journal, vol. 15, no. 1, 2019, pp. 42-50, Accessed 18 November 2020.

3. Cankurtaran, Damla. “Comparing the effectiveness of ultrasound guided versus blind genicular nerve block on pain, muscle strength with isokinetic device, physical function and quality of life in chronic knee osteoarthritis: a prospective randomized controlled study.” Korean J Pain, vol. 33, no. 3, 2020, pp. 258 - 266, Accessed 18 November 2020.

4. Erdem, Yusuf. “The Efficacy of Ultrasound-Guided Pulsed Radiofrequency of Genicular Nerves in the Treatment of Chronic Knee Pain Due to Severe Degenerative Disease or Previous Total Knee Arthroplasty.” Med Sci Monit, vol. 25, 2019, pp. 1857 - 1863, Accessed 18 November 2020.

5. Fonkoué, Loïc. “Distribution of sensory nerves supplying the knee joint capsule and implications for genicular blockade and radiofrequency ablation: an anatomical study.” Surgical and Radiologic Anatomy, vol. 41, 2019, 1461–1471(2019), Accessed 18 November 2020.

6. Güzelküçük, DemIr. “A different approach to the management of osteoarthritis in the knee: Ultrasound guided genicular nerve block.” Pain Medicine, vol. 18, no. 1, pp. 181 - 183, Accessed 18 November 2020.

7. Kim, Doo-Hwan. “Ultrasound-Guided Genicular Nerve Block for Knee Osteoarthritis: A Double-Blind, Randomized Controlled Trial of Local Anesthetic Alone or in Combination with Corticosteroid.” Pain Physician, vol. 21, 2018, pp. 41 - 51, Accessed 18 November 2020.

8. Protzman, Nicole. “Examining the feasibility of radiofrequency treatment for chronic knee pain after total knee arthroplasty.” PM&R, vol. 6, no. 4, 2014, pp. 373 - 376, Accessed 18 November 2020.

9. Sahoo, Rajendra K. “Genicular nerve block for postoperative pain relief after total knee replacement.” Saudi J Anaesth, vol. 12, no. 2, 2020, pp. 235 - 237, Accessed 18 November 2020.

This post was written by Julia Sobel MD, with editing from Jessica Oswald MD, Charles Murchison MD and Amir Aminlari MD.

Case 25: Aortic Dissection

A 44 year old male with a history of heroin abuse presents to the emergency department with altered mental status.  Per EMS, the patient was found on the street with decreased level of consciousness and poor respiratory effort.  EMS was concerned about opioid overdose, and he was treated with 4mg Narcan, with improvement in his mental status.  

Upon arrival to the ED, he was noted to be agitated and tachypneic with RR in the 40’s.  

Vitals: BP 90/65 mmHg, HR 110, O2 100% on RA, glucose 158.

He is alert and oriented to person, month, and place, but appears agitated and confused.  He denies any complaints other than shortness of breath, and states he felt fine before using heroin.  He denies any past medical history.

Exam notable for tachycardia, diffuse rhonchi throughout all lung fields, 2+ nonpitting lower extremity edema.  He is neurologically intact with 2+ pulses throughout.

A bedside echocardiogram was performed, what do you see?  What are your next steps?

PS long
dilated aortic root
aortic dissection suprasternal ultrasound
abdominal aortic dissection ultrasound
abdominal aortic dissection ultrasound
dissection to iliacs ultrasound

Answer and Learning Points


The first two images show a parasternal long-axis view, with a dilated aortic root measuring approximately 4.2cm.  Also notice the pericardial effusion with a homogenous layer that appears fixed to the pericardium.  At the time it was unclear whether this represented a clot within the pericardial sac, or was superficial to it.

Given the dilated aortic root, a suprasternal short-axis view was obtained to assess the proximal aorta, with the short axis view seen on the third image.  A flap was visualized in the aortic lumen, significant for an ascending aortic dissection.  The dissection was then visualized in the abdominal aorta, extending distal to the common iliac arteries, seen in the last images.

The patient was placed on esmolol drip and later required vasopressor support.  CT angiography was obtained, confirming a Type A aortic dissection.  He was transferred to a nearby hospital for emergent repair of his ascending and descending aortic dissection.  

Per the operative report, the patient had developed a significant pericardial effusion by the time he reached the OR, and the visualized homogenous layer above most likely represented a blood clot within the pericardium.

Learning Points:

    • While CTA remains the gold standard for diagnosis of aortic dissection, POCUS remains a great tool for diagnosing both ascending and descending aortic dissection, particularly in the unstable patient.
    • In addition to directly visualizing the dissection flap, TTE can also be used to identify patients with high risk features, such as those with cardiac tamponade, severe aortic dilatation, severe aortic regurgitation, regional wall motion abnormalities, and decreased ejection fraction (1).
    • TTE has been shown to have a sensitivity of 78-90% and specificity 87-96% for type A dissection in older studies (2,3), and in more recent studies showing improved sensitivity up to 97-99% (1,4,5) and specificity 100% (4) with improved image quality.
    • The suprasternal notch views are particularly useful in evaluating the proximal ascending aorta, and allow the operator to assess for aortic dissection, coarctation, dilatation of the aortic arch, and retrograde flow from the descending aorta.


1. Sobczyk D, Nycz K. Feasibility and accuracy of bedside transthoracic echocardiography in diagnosis of acute proximal aortic dissection. Cardiovasc Ultrasound. 2015;13:15.

2. Evangelista A, Flachskamp FA, Erbel R, Antonini-Canterin F, Vlachopoulos C, Rocchi G, et al. Echocardiography in aortic diseases: EAE recommendations for clinical practice. Eur J Echocardiogr. 2010;11:645–58. doi: 10.1093/ejechocard/jeq056.

3. Nienaber CA, von Kodolitsch Y, Nicolas V, Siglow V, Piepho A, Jaup T, et al. The diagnosis of thoracic aortic dissection by noninvasive imaging procedures. N Engl J Med. 1993;328:1–9. doi: 10.1056/NEJM199301073280101.

4. Cecconi M, Chirillo F, Constantini C, Iacobone G, Lopez E, Zanoli R, et al. The role of transthoracic echocardiography in the diagnosis and management of acute type A aortic syndrome. Am Heart J. 2012;163(1):112–8. doi: 10.1016/j.ahj.2011.09.022.

5. Nazerian, P., Vanni, S., Castelli, M. et al.Diagnostic performance of emergency transthoracic focus cardiac ultrasound in suspected acute type A aortic dissection. Intern Emerg Med9, 665–670 (2014).

This post was written by Rachna Subramony MD, Alex Anshus MD, with editing from Sukhdeep Singh MD, Charles Murchison MD and Amir Aminlari MD.

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