VOTW: Twinkle Artifact

This week's VOTW is brought to you by Dr. Sanghvi and the UST!

An 80 year old male w/ hx of CVA, non-verbal, PEG dependence, hx urosepsis presented from a nursing home w/ hypotension and “rule out sepsis”. Given the broad differential, the UST performed multiple scans including aorta, echo, chest, FAST, renal and bladder. The left kidney showed hydronephrosis and a POCUS of the bladder was performed which showed...

Clip 1 shows a transverse view of the bladder w/ color doppler placed over the L ureterovesicular (UVJ) junction demonstrating “twinkle artifact” 🌟. This indicates the presence of a stone!

The stone can also be seen without color doppler in clip 2 as a hyperechoic structure with posterior acoustic shadowing. It is associated with upstream hydroureter which can be seen as the clip fans thru. The rectum posteriorly is also distended and filled w/ stool.

Twinkle Artifact

Twinkle artifact

While we often only find indirect signs for ureteral stones on POCUS (hydronephrosis/hydroureter), you might sometimes be able to find the culprit stone on your bladder views. They are easy to miss since the bladder wall is also echogenic, especially if the stone is small. This is where twinkle artifact can be useful!!

When color doppler is used over a rough, hyperechoic, irregular object like a stone, the ultrasound waves get reflected internally within the stone, tricking the machine into thinking that there is movement, resulting in the stone being highlighted by a rainbow doppler signal. Sometimes it will have a rainbow tail extending away from the probe.

The presence of twinkle artifact has a high positive predictive value for the presence of kidney stone (1) and is more sensitive for detection of small stones than is acoustic shadowing (2).

Back to the patient

A CTAP showed three obstructing L ureteral stones, largest being 9mm. Urology was consulted and patient underwent L ureteral stent placement with findings of “pus behind left ureteral stone”. The patient was admitted to the MICU for septic shock.

References

1. Dillman J, Kappil M, Weadock W et al. Sonographic Twinkling Artifact for Renal Calculus Detection: Correlation with CT. Radiology. 2011;259(3):911-6. doi:10.1148/radiol.11102128 

2. Hosn S, Rutten C, Murphy A, et al. Twinkling artifact. Reference article, Radiopaedia.org (Accessed on 20 Feb 2024) https://doi.org/10.53347/rID-21828

VOTW: Interstitial Ectopic Pregnancy

This week’s VOTW is brought to you by… none other than our fantastic ED Medical Director Dr. Nubaha Elahi and Dr. Waters!

A 44 year old female G5P3 w/ hx of Essure procedure (a 99.3% effective method of contraception) presented to the ED with bilateral eye swelling x1 week. She also had a positive home pregnancy test and vaginal spotting. Without being mislead by the initial chief complaint on a busy fast-track shift the team performed a POCUS of the pelvis which showed...

Clip 1 shows a transabdominal view of the uterus with an empty gestational sac and a thick walled complex R adnexal cyst/mass. In the setting of a bHCG of 37000, this is concerning for an ectopic pregnancy!

Clip 2 shows a transvaginal view of the uterus with an eccentrically located gestational sac containing a fetal pole. Given the concern for interstitial ectopic, the team measured the endomyometrial mantle thickness (nice!) which was 1cm (still within normal range, however approaching the 8mm cutoff).

**The Essure procedure involved inserting metal coils in bilateral fallopian tubes to cause scarring. In 2018 it was taken off of the market because it was associated with many complications including ecotpic pregnancies. 

Endomyometrial mantle thickness measurement

Interstitial ectopic

An interstitial ectopic is a pregnancy implanted in the myometrium. It carries a higher rate of shock and hemoperitoneum and higher maternal mortality compared to the other ectopic pregnancies due to the highly vascular myometrium (1)

Think about interstitial ectopic pregnancy if you see an eccentrically placed gestational sac and measure the EMM.

Endomyometrial mantle (EMM) measurement

• EMM = thickness of the endometrium + myometrium

• Measure from outer edge of the gestational sac to outer edge of the uterus at the THINNEST portion that you see (image 1)

• EMM <8mm is concerning for an interstitial ectopic pregnancy

Back to the patient

OBGYN was consulted who admitted the patient for a laparoscopic hysterectomy. The final diagnosis was right interstitial ectopic pregnancy!

We’ve reviewed many ectopic pregnancy cases caught on POCUS recently- an example of a diagnosis where POCUS truly is saving lives! Keep up the great work!

References:

1. Rastogi R, Gl M, Rastogi N, Rastogi V. Interstitial ectopic pregnancy: A rare and difficult clinicosonographic diagnosis. J Hum Reprod Sci. 2008 Jul;1(2):81-2. doi: 10.4103/0974-1208.44116. PMID: 19562051; PMCID: PMC2700669.
   

VOTW: Thoracic Aortic Aneurysm

This week’s VOTW is brought to you by Dr. Ye, Dr. J Yang and Dr. Quinn!

A 58 year old male presented to the ED after fall. He was tachycardic to 120s, febrile and diagnosed with Flu A as well as alcohol withdrawal. He had an elevated troponin for which a POCUS was performed which showed…

Clip 1 shows a parasternal long axis view of the heart with multiple findings. First there is a pericardial effusion with possible RV collapse during systole concerning for tamponade. There is also a large, ovular, immobile, structure approximately 7cm in diameter where the left atrium should be. Based on our knowledge of anatomy, the differential includes dilated fluid-filled esophagus or thoracic aortic aneurysm.

The answer was found on CT chest to be a 7cm x 6cm descending thoracic aortic aneurysm (TAA) with a intra-aneurysmal thrombus with marked mass effect on the left atrium (CT image below).

Since Dr. Danta already did a wonderful VOTW on cardiac tamponade, this weeks’ topic is the thoracic aorta!

POCUS for the thoracic aorta

We can evaluate the thoracic aorta on POCUS for aneurysm or dissection. Unlike the abodminal aorta, we can only visualize certain snippets of the thoracic aorta. This results in a lower sensitivity (67-90%) (1) and cannot be used as rule out test for dissection.

Best views for visualizing the thoracic aorta

1. Parasternal long view  – Aortic root, proximal ascending aorta, portion of descending aorta

2. Supra-sternal notch view – Aortic arch (here's a good video on how to get this view: https://www.youtube.com/watch?v=gv6yZNOIchE)

3. Parasternal short view - depending on your angle, you can sometimes see the descending aorta in its long axis

Normal diameter measurements

Thoracic aorta < 4cm (remember FOUR-acic aorta)

Abdominal aorta < 3cm

Iliac arteries < 1.5cm

Pearls

• Measure the aortic root distal to the sinus of valsalva from leading edge to leading edge.

•  The RV, aortic root, LA should appear 1:1:1 in size in the parasternal long view. If the ascending aorta looks larger than the LA or RV, this would be concerning for an aneurysm.

• Increase your depth on the parasternal long to include the descending aorta posterior to the left atrium. You might catch a descending thoracic aortic aneurysm or dissection and the descending aorta also helps differentiate pericardial vs pleural effusion.

Back to the patient

Both vascular surgery and cardiothoracic surgery were consulted for this patient during admission but he remained too sick from his medical illnesses that he was not deemed a candidate for surgical intervention.

References

1. Fengju Liu, Lianjun Huang. Usefulness of ultrasound in the management of aortic dissection. Rev. Cardiovasc. Med. 2018, 19(3), 103–109.

Happy scanning,

Your Sono team