Widened Mediastinum


Article Author:
Lauren Wackerman


Article Editor:
David Gnugnoli


Editors In Chief:
Susan Johnson
Alexandra Caley


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Trevor Nezwek
Radia Jamil
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Steve Bhimji
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beata Beatty
Nazia Sadiq
Hajira Basit
Phillip Hynes
Tehmina Warsi


Updated:
3/12/2019 11:28:47 AM

Definition/Introduction

A widened mediastinum is a feature often seen on a plain chest x-ray. When the mediastinum is greater than 6 to 8cm, depending on which source, it is noted to be wide. A wide mediastinum has many causes which include the following:

  • Thoracic aortic aneurysm of the ascending and proximal descending aorta
  • Aortic dissection of ascending and proximal descending aorta
  • Unfolding of the aorta
  • Traumatic aortic rupture
  • Hilar lymphadenopathy either infectious or malignant
  • Mediastinal masses like lymphoma, seminoma, thymoma
  • Mediastinitis
  • Cardiac tamponade
  • Fractured ribs or thoracic vertebrae

Issues of Concern

A widened mediastinum will often be first noted in the emergency department on a chest x-ray. The mediastinal borders are composed of the right heart, ascending aorta, superior vena cava, aortic knob, descending aorta, and the left heart. These structures are all contained between the right and left lungs. The mediastinum can be partitioned into three compartments from anterior to posterior, which is best viewed on the lateral film. The anterior compartment contains the heart, thyroid, and thymus. The middle mediastinal compartment includes the esophagus, trachea, and many lymph nodes. The posterior compartment is the paravertebral area and is primarily composed of the vertebral column.[1] The definition of a widened mediastinum is a measured mediastinal width greater than 6 to 8 cm, depending on which source you use.[2] This finding is very sensitive for major vascular injury in the setting of trauma but can have numerous additional associated pathologies, as noted above. Pathology causing a widened mediastinum may also compress or displace nearby structures, such as the trachea.

The first consideration when a widened mediastinum is noted on x-ray is the quality of the chest film as poor technique can cause this presentation. The proper distance for taking a standard PA chest x-ray is with 6 feet between the x-ray source and the detector plate. If the distance between the detector plate and the x-ray source is closer than 6 feet, the structures in the film will appear larger and less sharp. Additionally, an AP chest x-ray, typically obtained as a portable chest x-ray, is taken at a closer distance and therefore also reveals larger and less sharp structures.  Patient positioning also plays an important role. If the patient is rotated or slouched, the mediastinum may appear falsely widened. After you have ensured the processing of an adequate film, the second consideration is to compare the chest x-ray to prior studies, if available. Typically, more chronic causes of a widened mediastinum, such as a mass or lymphadenopathy, cause focal widening, whereas acute causes of a widened mediastinum, like infection or bleeding, cause diffuse, generalized widening.[3] After ensuring that both the execution of the radiograph was with proper technique and the widened mediastinum is a new finding, it is time to pursue this finding further.

Clinical Significance

The most significant life-threatening concern associated with a wide mediastinum is an acute aortic rupture or aortic dissection. Additional imaging must be obtained to investigate these diagnoses.[4] In a stable patient, CT angiography of the chest is the best study for aortic pathology. However, if there is concern that the patient is unstable, they should not be transported to the radiology suite. In this instance, bedside ultrasound is an option which may reveal aortic pathology. 

In all cases, both immediate and potential causes of a widened mediastinum must merit consideration and be ruled out.


  • Image 8722 Not availableImage 8722 Not available
    Image courtesy S Bhimji MD
Attributed To: Image courtesy S Bhimji MD

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Widened Mediastinum - Questions

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A patient presents to the local emergency department after sustaining acute head trauma. Physical exam reveals blunt trauma to the left parietal region, no additional findings. Chest x-ray, which was performed as part of the trauma workup, shows a widened mediastinum. What is the next step in the management of this patient?



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An 18-year-old male presents for a complaint of chest pain. The patient reports a dry cough for the past two weeks and now reports right-sided chest pain that is worse with coughing. The patient has been taking NSAIDs at home with mild improvement of his symptoms. Physical exam reveals tenderness along the lateral aspect of the lower ribs on the right side. EKG shows a normal sinus rhythm with no acute findings. Chest x-ray reveals a widened mediastinum. This is an upright chest film with good positioning and prior CXR does not reveal the same findings. Laboratory studies reveal a mildly elevated WBC and troponin is normal. Which of the following should be done regarding this finding?



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Which of the following is in the differential diagnosis for an adult with an incidental finding of a widened mediastinum on chest x-ray?



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A patient arrives by private vehicle after being thrown off of his bike during a BMX race earlier today. The patient denies head strike or loss of consciousness and has been alert and at his baseline mentation since the incident. The patient developed some chest pain as the day progressed, which is why he presented to the ED. He undergoes triage but then becomes hypotensive with a blood pressure of 82/64 mmHg. A portable chest x-ray is performed and reveals the presence of a wide mediastinum. A liter of normal saline is hung and a second IV is being obtained however repeat blood pressure is 63/32 mmHg. An aortic rupture is suspected as a cause of the patient's hypotension. What test should be done at this time to confirm the leading diagnosis?



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An 18-year-old medical student has a positive PPD test and therefore requires a subsequent chest x-ray to rule-out diagnosis of tuberculosis. Chest x-ray is positive for a widened mediastinum. What is the next step in his management?



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A 32-year-old male presents to the emergency medical services after involvement in a motor vehicle collision in which he was the restrained passenger. He is complaining of mild chest pain and a slight headache. His vital signs are normal and physical exam is positive for a 2 cm non-bleeding laceration to the left frontal region of his forehead. Chest x-ray is performed and shown below. At what point is this a worrisome finding?

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Attributed To: Image courtesy of S Bhimji MD



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Widened Mediastinum - References

References

Goizueta AA,Bhimji SS, Anatomy, Thorax, Lung Pleura And Mediastinum 2018 Jan;     [PubMed]
Taghavi S,Askari R, Mediastinal Trauma 2018 Jan;     [PubMed]
Gutierrez A,Inaba K,Siboni S,Effron Z,Haltmeier T,Jaffray P,Reddy S,Lofthus A,Benjamin E,Dubose J,Demetriades D, The utility of chest X-ray as a screening tool for blunt thoracic aortic injury. Injury. 2016 Jan;     [PubMed]
Ong D,Cheung M,Cuenca P,Schauer S, Clinical Utility of Routine Chest X-Rays During the Initial Stabilization of Trauma Patients. Southern medical journal. 2019 Jan;     [PubMed]

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