Critical Point #2: The Incomplete Scan

Once again, we are going to look at some ultrasound images critically for technique. Hitting upon the QA questions I gave you in last month's post, we'll begin with: Are these images adequate? The most common reason to have inadequate scans is that images are left out of a protocol or set that gets grouped together to make a diagnosis.

This week we are going to discuss the Renal protocol. As you may recall, a Renal protocol should include the following images at minimum:
1. Right kidney longitudinal
2. Right kidney transverse
3. Left kidney longitudinal
4. Left kidney transverse
5. Bladder (long or transverse)

In recent months I have noticed a trend that people believe that the RUQ or LUQ view may count as the longitudinal kidney view. At times, it may, but most of the times it does not. Case in point, what is wrong with the image below?


Well, although it does give us a nice view of Morrison's pouch and the diaphragm, which are essential to the FAST exam, it does not give us a complete view of the kidney. The good news is that it does include the renal collecting system as evidenced by the hyperechoic center portion of the kidney, but it does not allow us to interrogate the inferior pole of the kidney. What if the patient has a large cyst or tumor on the inferior pole of the kidney which may account for their pain? You must interrogate the entire organ in order to make a clinical decision and diagnosis.

So, you ask "How can I get around that pesky rib that is shadowing out the inferior pole of the kidney?" Here are a couple of suggestions:
1. Slide your probe down 1 rib space. This will take the focus off the kidney-liver/ spleen-kidney junction and focus on the kidney. Many times this will allow complete visualization of the kidney.
2. Sliding the probe more anteriorly, keeping the kidney in focus will often time allow you a complete picture of the kidney.
3. If that rib shadow is getting in the way no matter what, you may need to take several pictures to fully interrogate the kidney. So if you cannot get away from the rib shadow, work around it. I will often take a picture of the rib shadow bisecting the kidney, indicating to the reviewer that the rib space is tight:

This allows me to take a longitudinal measurement since both superior and inferior poles are visible.
Now I look at each pole separately. I slide my probe above the pesky rib and angle up downward to the patient's feet. This allows complete visualization of the superior and mid kidney, while blocking out the inferior pole with rib shadow.


I then slide down over that rib toward the patient's feet and angle up toward the patient's head. This image now focuses on the mid and inferior pole of the kidney.


I realize that this seems time consuming but it can be done pretty quickly as this clip illustrates:

Right Kidney Longitudinal View from UF-Jax Emergency Medicine on Vimeo.

Once the longitudinal view has been obtained, turn your probe counterclockwise 90 degree's to the patient's right to obtain the transverse view of the kidney. This seems to be easier to document since it is much easier to get between ribs in the transverse plane. Although you only need to submit 1 picture, please remember to fan through the entire organ in the transverse plane and take a representative picture. Therefore, if you have a cyst or a stone visible, take a picture of that area and denote which portion of the kidney you have in the image (superior, inferior, mid).
For the last portion of the renal exam, head to the pelvic region to scan the bladder. Remember to angle your probe to the patient's feet in order to locate the bladder. I usually begin a transverse view and then turn into a longitudinal plane. A representative picture of the bladder in either plane is acceptable.


That now completes your basic Renal Scan Protocol!

January Case #3: Abdominal Pain-Discussion

The patient has appendicitis with a fecolith visualized in the appendiceal lumen. He under went a laproscopic removal of his appendix and was discharged home in 2 days.

Appendicitis

Using ultrasound to diagnose appendicitis is not a new technique, having first appeared in the literature in 1986. Multiple studies have illustrated the benefits of graded compression ultrasound to diagnose appendictis, with sensitivities ranging from 89-95% and specificitites of 95-100%. In this technique, the sonologist uses a linear high freqency transducer to apply a constant pressure to the right lower quadrant. Bowel loops will normally compress or become displaced from view when pressure is applied. In the case of appendicitis, the appendix is inflamed and non-compressible. It appears as a blind ended tubular pouch, which lacks peristalsis and compressibility. It should measure >6mm in diameter and may contain a fecolith, which will appear as a hyperechoic structure in the lumen with distal shadowing. Other signs that confirm appendicitis are an increase in the brightness or echogenicity of the periappendiceal fat. When color flow is applied to the acutely inflamed appendix, there may be a increased amount of flow in the wall circumferentially.

The easiest way to perform graded compression ultrasound to diagnose appendicitis is to have the patient localize their maximal point of pain with 1 finger. This has been shown to increase the ability to find the appendix and also can reduce exam time. Using a constant pressure to displace overlying bowel, the RLQ should be interrogated in both longitudinal and transverse planes. The appendix is easiest to identify in the transverse plane, appearing as a target with multiple layers of echogenicity, corresponding to the different layers within the bowel wall.
Once it has been identified, it should be examined in both planes. Attempts at compressibility should be made- if the appendix compresses or "winks" at you, then it is unlikely to be appendicitis. In appendicitis, the appendix may be displaced posteriorly, but the walls should not compress. Measurements of the diameter should be taken and color flow may also be placed on the appendix to denoted an increase in color flow (http://www.radiologyworld.com/appendicitis.gif). Interrogate the entire appendix before making your final diagnosis to ensure that you are not missing a fecolith or fluid collection that may indicate and abscess.


Puylaert JB. Acute appendicitis: US evaluation using graded compression. Radiology. 1986; 158(2):355 -60

January Case #3: Abdominal Pain

25 y/o WM presents to the ED with complaints of periumbilical abdominal pain for 2 days, which is now moved to his RLQ. He denies N/V, F/C.

PMHx: Asthma
PSHx: none
Meds: none
Allergies: NKDA
Soc Hx: denies ETOH, drugs or tobacco

PE:
VS: BP 125/70, P 90, R 18, T 98.5
GEN: WNWD, WM, NAD
CHEST: CTA B, nonlabored
CV: RRR, no M/R/G
ABD: TTP RLQ, garding, no rebound, +BS, guiac-
EXT: no C/C/E

Bedside ultrasound is performed:


What is the diagnosis?

What is the hyperechoic structure within the lumen?


Special thanks to Ruben Font for submitting this case!

January Case #2: Flank Pain- Discussion

This patient has a staghorn calculus. After the bedside US was performed, the patient underwent a CT scan which confirmed the diagnosis and noted dilated collecting system and thinning of the cortex on the affected kidney. It also demonstrated hypertrophy of the contralateral kidney with mild hydronephrosis.

Urology was consulted and the patient was admitted to the Hospitalist service. She had a nuclear medicine renal scan which showed her renal function to be 79% on the left and only 21% on the right. She then underwent a right nephrectomy 8 days later. Her urine culture grew out Klebsiella.

Renal Calculi

Renal calculi, in general, affect around 10% of the population. Stones are usually comprised of calcium or uric acid. They are most commonly found in one of three areas: the UPJ (uretero-pelvic junction), the UVJ (uretero-vesicular junction) and the point at which the ureter crosses the pelvic brim. The appear on ultrasound as a hyperechoic crescent shape, usually associated with acoustic shadowing. You may also see the twinkle sign with renal stones (http://rad.usuhs.edu/medpix/kiosk_image.html?mode=case_viewer&imid=38513&pt_id=11272&quiz=&th=&table=card&showall=#pic). This sign is a color Doppler artifact that appears as a combination of red and blue Doppler signals distal to a stone. Small stones may not create an acoustic shadow, but by placing color Doppler on the kidney in a patient suspected to have renal colic, a stone may be identified by noting a twinkle sign.

Renal stones may cause complete or partial blockage of the ureter, resulting in hydroureter and hydronephrosis. A dilation of the ureter and renal collecting system may be present, evidenced by anechoic dilation of these structures. The ureters can be assessed by looking for ureteral jets in the bladder. Looking at the bladder in the transverse plane, scan through until the posterior wall appears flat horizontally. Using color Doppler, ureteral jets appear as red colored flame. If a jet is identified, it is reassuring that the ureter is at least partially patent.
A staghorn calculus is a stone that fills the renal pelvis branching into the calyxes, causing their dilation. They are most often composed of struvite (magnesium ammonium phosphate) and/or calcium carbonate apatite. These stones are often called 'infected stones' since they are usually associated with urinary tract infections with urea splitting organisms. These stones result in obstruction, either by obstructing the collecting system or the ureter. If left untreated, staghorn calculi can cause a kidney function to deteriorate causing end-stage kidney disease. As these stones are likely infected, they pose a risk of progression to sepsis. Thus, most patients require definitive surgical treatment.
On ultrasound, they may appear as various shapes depending on the scan plane, multiple curvilinear structures that outline the renal pelvis. They may or may not have distal shadowing. You may see hydronephrosis and a dilated kidney.

January Case #2: Flank Pain

30 y/o AAF with c/o right flank and back pain for 2 days. +F/C, N/V. Pt c/o thick, discolored urine. She denies vaginal D/C or bleeding or diarrhea. Decreased PO intake.

PMHx: hypothyroidism, kidney stones, UTIs in past
PSHx: none
Meds: synthroid
FHx: none
Social Hx: denies tobacco or drugs, occasional ETOH
Allergies: NKDA

PE:
VS: BP 108/66, P 120, R 18, T 98.6, POx 96% (RA)
GEN: thin AAF, NAD
HEENT: MMM , OP clear
CV: tachycardic, RR, no M/R/G, 2+ pulses B
CHEST: CTA B
ABD: soft, mild RUQ TTP, moderate suprapubic TTP, no guarding or rebound, +BS, +R CVAT

Bedside US is used to asses her urinary tract:












What is the diagnosis?

Thanks to Kristin McKee for submitting this case!

January Case #1: Painful Forearm- Discussion

This patient has a forearm psuedoaneurysm of an interosseous artery. He underwent a CTA of the right forearm which shows nonvisualization of the ulnar artery within the proximal forearm. The CTA was unable to fully evaluate the pseudoaneursym (possible due to its size- there was a small blush of contrast within the region. This was thought to represent artifact vs. hematoma vs. pseudoanuerysm).

The patient ultimately underwent angiography with embolization of the pseudoaneurysm. After successful embolization, the patient's radial artery was widely patent, but the ulnar artery teminates at the site of the pseudoaneysm. Ulnar artery filling was perserved only by retrograde filling through the palmar arch.

Pseudoaneurysm

Pseudoaneurysm or false aneurysm, is a tear in the arterial wall allowing blood to leak from the vessel into the surrounding tissue. The resulting hematoma walls off the surrounding tissue, creating a cavity. Blood leaking from the artery then swirls within this cavity, creating the classic findings on ultrasound. It is a complication most commonly described after diagnostic cardiac catheterizaiton through the femoral artery. It is indeed a "false" aneursym, as the intimal layers of the arterial wall do not comprise the borders of the outpouching. On color flow doppler, you can clearly see blood swirling in the cavity. This is termed the "ying-yang" sign, which is blood swirling both toward the probe (seen in red) and away from the probe (in blue).
Note that the patent vessel deep to the pseudoaneurysm maintains its normal size and shape. Spectral doppler of the stalk of the psuedoanuerysm would demonstrate turbulent flow.

January Case #1: Painful Forearm

25 yo WM presents with increasing right forearm pain and swelling for the past 6 days. He is 5 weeks status post fasciotomy for stab wound to the R forearm and resultant compartment syndrome. Patient denies erythema, fever, chills, or odor/purulence of the incision sites. He does endorse chronic numbness of the right 2nd digit since the injury. The pain is “throbbing.” He is undergoing physical therapy, but has been gradually decreasing compliance with sessions secondary to the increasing pain.
PMHx: Anemia, secondary to blood loss
PSHx: R volar forearm fasciotomy 5 weeks ago
Meds: Percocet, Gabapentin
Allergies: NKDA
FHx: negative
Soc Hx: occasional ETOH, chews tobacco

PE:
Vitals: BP: 132/78, Pulse: 101, RR: 16, Temp: 98.8, Pox: 100%
GEN: A&O x 3, NAD
HEENT: NCAT
CV: RRR, no M/R/G, HR 92 now
RESP: CTA B
ABD: soft, NTND, +BS
EXT: 2+ radial pulses bilaterally, R forearm tight and significantly swollen. Granulation tissue present over fasciotomy sites. No evidence of erythema. No purulence. No axillary lymphadenopathy. Decreased light touch sensation to all fingers on R hand. Wrist held in flexion, with limited extension secondary to pain.

Bedside ultrasound of the right forearm shows:

January Case #1-1 from UF-Jax Emergency Medicine on Vimeo.


January Case #1-2 from UF-Jax Emergency Medicine on Vimeo.






January Case #1-3 from UF-Jax Emergency Medicine on Vimeo.

What’s the Diagnosis?

Thanks to special guest contributer, Dr. Murray Baker, for this case! Excellant job!