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 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. Educational Objective: MTS is characterized by the compression of the left iliac vein by an overriding right iliac artery. References: 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 Baron HC, Sharms J, Wayne M. Iliac vein compression syndrome: A new method of treatment. Am Surg. 2000;66:653-655.]]
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::