A Fast Diagnosis

CASE:

HPI: Johnny is a 5 year-old boy, previously healthy, who presents with fever, emesis, and abdominal pain for one week. Eight days ago, he had fevers as high as 102F, but was otherwise feeling well. Four days prior to admission his fevers resolved, but he developed emesis and abdominal pain, which continued daily until presentation.

Vitals:  Temp 37.4°F | Pulse 106 | Resp 20 | SpO2 98% | BP 139/96

Exam: Appears fatigued. Abdomen distended with increased bowel sounds, tympany to percussion, and diffuse tenderness. No hepatosplenomegaly. No respiratory distress or increased work of breathing.

You decide to take an ultrasonographic look at his abdomen, thinking this could be appendicitis or intussusception. You throw the probe on the patient’s right and left upper quadrants, and see the following:

How do you interpret these clips?

These images demonstrate bilateral pleural effusions and B-lines (see Figure 1):

Figure 1: Right and left upper quadrant views of abdomen, respectively, demonstrating bilateral pleural effusions (green arrows) and B-lines (blue arrows).

What would be your next step?

After obtaining these images, it was decided to obtain dedicated images of the lung, leading to the procurement of the following clips:

How do you interpret these clips?

Both sets of images demonstrate diffuse B-lines bilaterally, as well as pleural effusions (Figure 2):

Figure 2: Right and left posterior lung fields, respectively, with diffuse B-lines bilaterally (blue arrows), as well as pleural effusions (green arrows).

What are B-lines?

B-lines are vertical, hyperechoic lines originating from pleura, which obliterate normal horizontal A-lines in their wake.

• Isolated B-lines may be a normal finding in healthy lungs, but if there are three or more of them in one interspace they are considered pathologic.
• They are caused by a decreased difference in density or acoustic impedance between the pleura and parenchyma, and represent fluid in the alveolar or interstitial spaces.
• Several potential physiologic causes of this artifact include: (1)

o   Intra- or interlobular septal thickening
o   An increase in lung parenchymal water content
o   An increase in lung parenchymal density
o   Decreased lung ventilation.  

• If diffuse, they can signify:

o   Pulmonary edema
o   Acute Respiratory Distress Syndrome (ARDS)
o   Congestive Heart Failure (CHF)
o   Interstitial fibrosis.

• If local, they can represent:

o   Pneumonia
o   Pulmonary contusion
o   Infarct 

How do pleural effusions appear on ultrasound?

• FAST View: Anechoic triangle above the diaphragm in RUQ and LUQ views.
• Lung may be seen as a triangular structure superior to the diaphragm that exhibits a wave-like movement as if floating in the fluid.
  
  o   In our case, the lung has fluid in the interstitial spaces, and is therefore appreciated as B-lines as is described above.

Did you know that ultrasound is more sensitive than chest radiograph for pleural fluid?

Ultrasound can detect physiologic amounts of pleural fluid (5mL), but becomes more reliable with increasing volumes, and is 100% sensitive for detecting effusions >100mL. (3)

Contrast this with chest radiography, in which blunting of the costophrenic recesses are seen only after >200mL of pleural fluid has accumulated.

What could cause these findings in the setting of this patient’s signs and symptoms?

The patient’s B-lines are bilateral and diffuse, thus the team has concern for pulmonary edema. Given his lack of respiratory distress, normal oxygen saturations, and hemodynamic stability, it would be unlikely for him to have ARDS, CHF, or interstitial fibrosis. This is further supported by a cardiac ultrasound that reveals normal global systolic function.

You get more information from mom, who states that Johnny’s face has appeared puffy and his abdomen has been distended for the past several days. 

Putting together Johnny’s fever, emesis, abdominal pain and distension, puffiness,  and hypertension, along with his ultrasound findings of pulmonary edema and pleural effusions, the team suspects nephrotic syndrome. A urinalysis is sent, which confirms the team’s suspicion by demonstrating the following:

• 100 protein
• 17 WBC
• 129 RBC
• Urine protein:creatinine ratio 1.41 (normal 0.00 – 0.17)

What is the final diagnosis?

Acute post-infectious glomerulonephritis

This is characterized by inflammation and/or cellular proliferation of the glomeruli, and may manifest as an acute nephritic or nephrotic syndrome.

• Nephritic syndrome consists of hematuria, proteinuria, and evidence of volume overload
• Nephrotic syndrome consists of severe proteinuria, hypoalbuminemia, and edema.

o The most common cause of acute glomerulonephritis is poststreptococcal glomerulonephritis, but other infectious agents can also cause it.
o The classic triad of glomerulonephritis is hematuria, edema, and hypertension.
o The edema of glomerulonephritis is caused by excessive renal fluid and sodium retention. (2)

• Manifests initially in areas of low tissue resistance including periorbital, scrotal, and labial regions. Ultimately it becomes generalized.
• Symptoms include anorexia, fatigue, abdominal discomfort, and diarrhea.
• Fluid overload can also occur in the lungs as pulmonary edema or pleural effusions, but this is usually clinically asymptomatic, as in our patient. Both of these findings can be observed by ultrasound, as seen in our patient and explained above.

CASE CONCLUSION:

The patient was admitted to the hospital. He received Lasix, isradipine, and hydralazine for his volume overload and hypertension. At his one month follow up visit at nephrology clinic, he no longer had proteinuria, and his hypertension had resolved. It was felt that his glomerulonephritis was resolving.

PEARLS:

1. Bedside ultrasound can be a quick, inexpensive, and useful tool in parsing out undifferentiated abdominal pain, in conjunction with history and physical exam.
2. B-lines on ultrasound signify interstitial syndrome, which may represent pulmonary edema in the appropriate clinical setting.
3. Acute glomerulonephritis can cause fluid overload, which leads to generalized edema. This can cause abdominal pain and distension. It can also in some cases lead to pulmonary edema and pleural effusions.

FACULTY REVIEWERS:

Erika Constantine, MD

Max Rubinstein, MD

Robyn Wing, MD, MPH

References:

1. Smargiassi A, Inchingolo R, Soldati G, Copetti R, Marchetti G, Zanforlin A, et al. The role of chest ultrasonography in the management of respiratory diseases: document II. Multidisciplinary respiratory medicine. 2013;8(1):55.

2. VanDeVoorde 3, René G. Acute poststreptococcal glomerulonephritis: the most common acute glomerulonephritis. Pediatrics in review / American Academy of Pediatrics. 2015 Jan;36(1):3-13.

3. Soni NJ, Franco R, Velez MI, Schnobrich D, Dancel R, Restrepo MI, et al. Ultrasound in the diagnosis and management of pleural effusions. Journal of Hospital Medicine. 2015 Dec;10(12):811-6.

4. Karen S. Cosby and John Kendall MD, M D. Practical Guide to Emergency Ultrasound. Philadelphia, PA: Lippincott Williams & Wilkins; 2014.

5. “Lung Ultrasound Part 1.” http://www.ultrasoundpodcast.com/2013/02/lung-ultrasound-part-1/ Accessed Dec 2 2016.