2026 Clinician Corner - Heterotaxy syndrome: a rare risk factor for a pulmonary embolism in a young person

Abstract 

Heterotaxy syndrome, or situs ambiguus, is a rare congenital condition characterized by abnormal left-right positioning of thoracoabdominal organs. It often includes splenic anomalies such as polysplenia and vascular malformations like interruption of the inferior vena cava (IVC) with azygos continuation. These anatomical variants can impair venous return, increasing the risk of venous thromboembolism, particularly in young patients.  We present the case of an 18-year-old woman with obesity and long-term estrogen-containing oral contraceptive use who presented with acute bilateral pulmonary emboli. Initial imaging noted polysplenia, but the diagnosis of heterotaxy syndrome with IVC interruption and azygos continuation was not made until 5 months later during evaluation for recurrent chest pain. Hypercoagulable workup was negative, and anticoagulation was continued due to ongoing thrombotic risk. This case highlights heterotaxy syndrome as an underrecognized contributor to venous thromboembolism in young individuals and underscores the importance of considering anatomical risk factors in cases of unprovoked thromboembolism. 

Keywords:  Hematology; heterotaxy syndrome; pulmonary embolism; situs ambiguus; thrombophilia

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Faculty credentials/disclosure 

The planners and faculty for this activity have no relevant financial relationships to disclose. The patient consented to the publication of this report.

Process

Click the "add to cart/begin" button, pay any relevant fee, take the quiz, complete the evaluation, and claim your CME credit.  You must achieve 100% on the quiz with unlimited attempts available.

  • By completing this process, you are attesting that you have read the journal article.

Expiration date:

Credit eligibility for this article is set to expire on January 1, 2027.

Learning Objectives

After completing the article, the learner should be able to:

  • Identify anatomical anomalies associated with heterotaxy syndrome, such as polysplenia and interrupted inferior vena cava with azygos continuation, and recognize their relevance in the context of unexplained venous thromboembolism. 

  • Implement appropriate long-term management strategies for patients with heterotaxy-associated venous thromboembolism, including anticoagulation and counseling on modifiable risk factors such as contraceptive use, obesity, and physical inactivity. 

  • Interpret thoracoabdominal imaging with attention to visceral situs and vascular anomalies to improve detection of underrecognized risk factors for deep vein thrombosis and pulmonary embolism. 

Key Points 

 

  • Heterotaxy syndrome, particularly with polysplenia and interrupted inferior vena cava (IVC) with azygos continuation, is a rare but important anatomical risk factor for venous thromboembolism in young patients. 

  • IVC interruption can lead to impaired lower-extremity venous drainage and venous stasis, increasing the risk for deep vein thrombosis and pulmonary embolism, even in the absence of inherited thrombophilia. 

  • Heterotaxy syndrome is frequently underrecognized on initial imaging, highlighting the importance of careful review of abdominal vasculature and visceral situs in patients with unexplained thromboembolic events. 

  • Management should include long-term anticoagulation in patients with heterotaxy-associated IVC anomalies and counseling on modifiable risk factors, such as avoiding estrogen-containing contraceptives. 

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Course summary
Available credit: 
  • 1.00 American Board of Internal Medicine (ABIM) MOC Part 2
    Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to 1.00 MOC points in the American Board of Medicine’s (ABIM) Maintenance of Certification (MOC) program. It is the CME activity provider’s responsibility to submit participant completion information to ACCME for the purpose of granting ABIM MOC credit.
  • 1.00 AMA PRA Category 1 Credit™
    The A. Webb Roberts Center for Continuing Medical Education of Baylor Scott & White Health is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.
  • 1.00 Attendance
Course opens: 
01/01/2026
Course expires: 
01/01/2027
Cost:
$25.00
Rating: 
0

Lindsay Mathys, BA1, Blake Oliaro, MD, MEng1,2, Srujan Kancharla, MD1,2, Vishnu Dubakula, DO1,2, and Meaghan Dubin, MD1,2 

 

1Texas A&M University College of Medicine, Round Rock, Texas, USA 

2 Baylor Scott & White Round Rock Medical Center, Round Rock, Texas, USA 

 

Corresponding author: Lindsay Mathys, BA, Texas A&M University College of Medicine, 3950 N A.W. Grimes Blvd., Round Rock, TX 78665 (e-mail: [email protected]) 

The planners and faculty for this activity have no relevant financial relationships to disclose. The authors report no funding. The patient consented to publication of this case report. 

Accreditation

The A. Webb Roberts Center for Continuing Medical Education of Baylor Scott & White Health is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.

Designation

AMA PRA Category 1 Credit™

The A. Webb Roberts Center for Continuing Medical Education of Baylor Scott & White Health designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

ABIM MOC

 Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to 1.0 MOC points in the American Board of Internal Medicine’s (ABIM) Maintenance of Certification (MOC) program. It is the CME activity provider’s responsibility to submit participant completion information to ACCME for the purpose of granting ABIM MOC credit.

 

Available Credit

  • 1.00 American Board of Internal Medicine (ABIM) MOC Part 2
    Successful completion of this CME activity, which includes participation in the evaluation component, enables the participant to earn up to 1.00 MOC points in the American Board of Medicine’s (ABIM) Maintenance of Certification (MOC) program. It is the CME activity provider’s responsibility to submit participant completion information to ACCME for the purpose of granting ABIM MOC credit.
  • 1.00 AMA PRA Category 1 Credit™
    The A. Webb Roberts Center for Continuing Medical Education of Baylor Scott & White Health is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.
  • 1.00 Attendance

Price

Cost:
$25.00
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