WBR0723
| Author | [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathology |
| Sub Category | SubCategory::Vascular |
| Prompt | [[Prompt::A 38-year-old woman presents to the physician's office complaining of pain and swelling in her left leg. Upon further questioning, she informs the physician that she recently returned to the United States from a vacation in Europe. Physical examination is remarkable for erythema, non-pitting edema, and tenderness of the left calf. In contrast, the right leg appears normal. Following appropriate work-up and imaging, the patient is diagnosed with May-Thurner syndrome. Which of the following anatomic findings best characterizes May-Thurner syndrome?]] |
| Answer A | AnswerA::Compression of the left iliac vein by an overriding right iliac artery |
| Answer A Explanation | [[AnswerAExp::MTS is characterized by the compression of the left iliac vein by an overriding right iliac artery.]] |
| Answer B | AnswerB::Compression of the left iliac vein by an overriding left iliac artery |
| Answer B Explanation | AnswerBExp::MTS is not characterized by the compression of the left iliac vein by an overriding left iliac artery. |
| Answer C | AnswerC::Compression of the left iliac vein by an overriding right iliac vein |
| Answer C Explanation | AnswerCExp::MTS is not characterized by the compression of the left iliac vein by an overriding right iliac vein. |
| Answer D | AnswerD::Compression of the left iliac vein by another overriding left iliac vein |
| Answer D Explanation | AnswerDExp::MTS is not characterized by the compression of the left iliac vein by another overriding left iliac vein. |
| Answer E | AnswerE::Compression of the left iliac vein by the iliac crest |
| Answer E Explanation | AnswerEExp::MTS is not characterized by the compression of the left iliac vein by the iliac crest. |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::
May-Thurner syndrome (MTS) is also called iliocaval compression syndrome because it is characterized by the compression of the left iliac vein by an overriding right iliac artery. Patients with MTS are typically young women who present with symptoms consistent with deep vein thrombosis (DVT). The exact incidence and prevalence are still unknown. Other risk factors that predispose patients to an increased risk of thrombosis are also implicated in MTS, including pregnancy and postpartum period, use of oral contraceptive pills, and prolonged immobilization. DVT in MTS is more common on the left side than the right side because of the anatomic hallmark of the disease, where compression of the left venous side impairs venous return on that side. However, mechanical compression may not be the only cause of DVTs among patients with MTS; it seems that chronic arterial pulsations from the right common iliac artery cause trauma to the venous wall leading to "spur formation" that also contributes to the formation of DVT among these patients. MTS is initially suspected based on history and physical examination. Work-up includes a venous duplex ultrasound, which may not always demonstrate the site of thrombosis and the status of the iliac vein. Accordingly, some physicians still prefer venography for a definitive diagnosis. Other useful tests may include CT scans with venous phases or MR venography. Unlike other causes of DVT, treatment of MTS includes an endovascular approach and stenting. Mousa AY AbuRahma AF. May-Thurner syndrome: update and review. Ann Vasc Surg. 2013;27(7):984-95 Oguzkurt L, Ozkan U, Tercan F, Koc Z. Ultrasonographic diagnosis of iliac vein compression (May-Thurner) syndrome. Diagn Interv Radiol. 2007;13(3):152-5]] |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::May, WBRKeyword::Thurner, WBRKeyword::Syndrome, WBRKeyword::May-thurner, WBRKeyword::DVT, WBRKeyword::Deep vein thrombosis, WBRKeyword::Edema, WBRKeyword::Erythema, WBRKeyword::Iliac, WBRKeyword::Vein, WBRKeyword::Thrombosis, WBRKeyword::Deep, WBRKeyword::Vein |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |