Case Report

Pulmonary Emboli Caused by Iliac Compression Syndrome without Leg Symptoms
Kazuma Kishi, Sakae Homma, Masateru Kawabata, Eiyasu Tsuboi, Koji Narui, Tatsuo Nakatani, Koichiro Nakata

Division of Respiratory Diseases, Toranomon Hospital, Tokyo, Japan

Address of Corresponding Author

Respiration 2002;69:269-272 (DOI: 10.1159/000063632)

 Outline

• Key Words
• Abstract
• Introduction
• Case Report
• Discussion
• Acknowledgment
• References

• Author Contacts
• Article Information
• Publication Details
• Drug Dosage / Copyright

  Key Words

• Iliac compression syndrome
• Pulmonary emboli
• Vena cava filter

  Abstract

Iliac compression syndrome is a clinical condition that occurs as a result of compression of the left common iliac vein by the overlying right common iliac artery. This syndrome most often affects young to middle-aged women, and patients usually have left leg symptoms. We report the unusual case of an 18-year-old male who had pulmonary emboli caused by iliac compression syndrome without leg symptoms. Combined venography and aortography confirmed the diagnosis. The patient was successfully treated with anticoagulants and vena cava filter insertion. Iliac compression syndrome should be considered when pulmonary embolism appears without obvious cause.

Copyright © 2002 S. Karger AG, Basel

 introduction

Iliac compression syndrome is a clinical condition that occurs as a result of compression of the left common iliac vein by the overlying right common iliac artery. This anatomic anomaly was first identified by McMurrich [1] in 1908. In 1956, May and Thurner [2] described intraluminal spurs in the left common iliac vein underlying the right common iliac artery in 22% of an autopsy series. In 1965, Cockett and Thomas [3] proposed the term 'iliac compression syndrome' to describe the clinical condition, but later authors frequently referred to the same syndrome as May-Thurner syndrome [4] or Cockett's syndrome [5].

This syndrome is most often found in women during the second to fourth decades of life [3]. The majority of patients are asymptomatic. When patients become symptomatic, the common symptoms and signs are left leg swelling, varicosity, pain, ulceration and deep vein thrombosis [6, 7]. Because of the mechanical nature of the obstruction, patients respond poorly to conservative therapy [3, 6, 7]. We present an unusual case of a young male with multiple pulmonary emboli caused by iliac compression syndrome without leg symptoms.

 case report

A 18-year-old man was admitted with dyspnea on exertion and hemoptysis. He had been well until 2 months earlier, when dyspnea on exertion had developed. Ten days before admission, he had begun to cough up a small amount of blood. He had noticed dyspnea while practicing basketball with his university team, but denied any trauma to his abdomen, pelvis, or legs. His medical and family histories were unremarkable. Physical examination on presentation revealed no abnormality. There was no edema, nor were there any varicose veins of the lower extremities.

Complete blood count, chemistry studies, prothrombin time and activated partial prothromboplastin time were normal. Subsequent evaluation of the patient's clotting factors revealed normal levels of protein C, protein S, antithrombin III and factor V Leiden. A chest radiograph showed slightly enlarged central pulmonary arteries without increased heart size. Helical CT scans of the chest revealed intraluminal filling defects in the interlobar and lower lobe pulmonary arteries bilaterally (fig. 1). Ventilation-perfusion scans showed normal ventilation but multiple segmental perfusion defects. The patient was diagnosed as having pulmonary thromboembolism, and anticoagulant therapy with intravenous unfractionated heparin was begun. Ultrasound examination of the pelvic and leg veins was performed, as the patient lacked any apparent predisposition to pulmonary thromboembolism. The ultrasound examination suggested thrombosis with extrinsic compression of the left common iliac vein. Thrombosis was confirmed by helical CT scan of the pelvis (fig. 2). A Greenfield filter was placed in the inferior vena cava because anticoagulant therapy alone was thought to be inadequate to prevent recurrent pulmonary emboli due to mechanical obstruction of the left common iliac vein. Bilateral simultaneous iliac venography combined with aortography clearly demonstrated compression of the left common iliac vein by the overlying right common iliac artery, with multiple dilated collateral veins (fig. 3). We concluded that the pulmonary emboli were caused by iliac compression syndrome. After anticoagulant therapy and the insertion of a vena cava filter, the patient's pulmonary symptoms resolved and he was discharged on warfarin. Repeat venography and ventilation-perfusion scans at 3 months showed no thrombus in the left common iliac vein and improvement of pulmonary emboli. The patient took warfarin for 2 years, and then it was withdrawn. Three months after warfarin withdrawal, a helical CT scan of the pelvis demonstrated signs of left iliac vein compression without thrombosis. The patient has been completely asymptomatic since discharge.

Fig. 1. Helical CT scan of the chest reveals intraluminal filling defects in the lower lobe pulmonary arteries bilaterally (arrows).

Fig. 2. Helical CT scan of the pelvis reveals a thrombus in the left common iliac vein (arrow).

Fig. 3. Combined venogram and aortogram reveals compression of the left common iliac vein by the overlying right common iliac artery with dilated collateral veins. A Greenfield filter (showing thrombus) was placed in the inferior vena cava. The aortogram was subtracted.

 discussion

Iliac compression syndrome was first described in 1908 [1], but it was not recognized as a clinical syndrome until the description by May and Thurner [2]. The pathogenesis of this syndrome is not fully understood, although it is postulated that compression of the left common iliac vein by the right common iliac artery leads to intraluminal spurs and subsequent venous obstruction [2]. This condition has been estimated to occur in 2-5% of patients with venous disorders of the lower extremities [6, 7].

The syndrome is most often found in women during their second to fourth decades of life, and patients usually have left leg symptoms [3, 6]. Of a total of 127 patients with this syndrome in the medical literature, 89 (70%) were women [8]. It is obvious that the large majority of patients are asymptomatic, as evidenced by the 22% frequency of intraluminal spurs found at autopsy [2] and the low incidence of clinical symptoms in patients [6, 7]. The most common symptom is swelling of the left lower extremity (25-100%). Other signs and symptoms include left leg pain (42-100%), varicosities (58-67%), and chronic venous stasis ulcers (6-25%) [8]. In 1967, Cockett et al. [9] reported that pulmonary embolus was the presenting symptom in about 25% of patients. However, interestingly, few cases with pulmonary embolism as the initial symptom have since been reported. Our patient developed multiple pulmonary emboli first, without any leg symptoms or signs.

Venography remains the gold standard for the diagnosis of iliac compression syndrome, because it can demonstrate collateral veins as well as the compression itself [10]. However, several noninvasive imaging modalities, including ultrasound examination, CT and most recently, magnetic resonance angiography (MRA) have been used to make the diagnosis [10, 11]. Ultrasound examination could be suitable as the first diagnostic test for detecting the presence of the syndrome. MRA can demonstrate the extent of venous thrombosis and the anatomic relationship of the vessels, making a definite diagnosis possible [11]. Although we have not performed MRA, it seems to be preferable to perform MRA prior to CT, especially in young or pregnant patients, because MRA eliminates the problem of radiation exposure. In our patient, combined venography and aortography clearly demonstrated the point where the left common iliac vein was compressed by the right common iliac artery.

Because of the mechanical nature of the obstruction, patients who have iliac compression syndrome respond poorly to conservative therapy [3, 6, 7]. Taheri et al. [6] argue that progressive symptoms will continue to develop in these patients, so the anatomic anomaly should be corrected as soon as it is identified. For this reason, surgical decompression [3, 6, 10] and more recently transluminal stenting have been recommended [12, 13, 14]. We started anticoagulant therapy and inserted a vena cava filter because our patient presented with pulmonary emboli, and anticoagulants alone were thought to be inadequate for treating his condition [12]. As our patient has been asymptomatic and without deep vein thrombosis, we maintained him on anticoagulant therapy for 2 years, although the optimum duration of anticoagulant therapy remains unknown. To our knowledge, this is the first case report of successful treatment of pulmonary emboli caused by iliac compression syndrome with anticoagulation and a vena cava filter.

Iliac compression syndrome is generally underdiagnosed and should be considered when pulmonary embolism appears without obvious cause.

 acknowledgment

We would like to thank Dr. David E. Midthun, Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, for reviewing the manuscript.

  References

1.

McMurrich JP: The occurrence of congenital adhesion in the common iliac veins and their relation to thrombosis of the femoral and iliac veins. Am J Med Sci 1908;135:342-346.

2.

May R, Thurner J: Ein Gefässsporn in der vena iliaca communis sinistra als Ursache der überwiegend linksseitigen Beckenvenenthrombosen. Z Kreislauf-Forsch 1956;45:912-922.

3.

Cockett FB, Thomas LM: The iliac compression syndrome. Br J Surg 1965;52:816-825. 

4.

Ferris EJ, Lim WN, Smith PL, Casali R: May-Turner syndrome. Radiology 1983;147:29-31. 

5.

Verhaeghe R: lliac vein compression as an anatomical cause of thrombophilia: Cockett's syndrome revisited. Thromb Haemost 1995;74:1398-1401. 

6.

Taheri SA, Williams J, Powell S, Cullen J, Peer R, Nowakowski P, Boman L, Pisano S: Iliocaval compression syndrome. Am J Surg 1987;154:169-172. 

7.

Taheri SA, Schultz RO, Hoover E, Milanowski L: Iliocaval compression syndrome. Contemp Surg 1992;40:9-15.

8.

Steinberg JB, Jacocks MA: May-Thurner syndrome: A previously unreported variant. Ann Vasc Surg 1993;7:577-581. 

9.

Cockett FB, Thomas LM, Negus D: Iliac vein compression. Its relation to iliofemoral thrombosis and the post-thrombotic syndrome. Br Med J 1967;2:14-19. 

10.

Akers DA, Creado B, Hewitt RL: Iliac vein compression syndrome: Case report and review of the literature. J Vasc Surg 1996;24:477-481. 

11.

Hurst DR, Forauer AR, Bloom JR, Greenfield LJ, Wakefield TW, Williams DM: Diagnosis and endovascular treatment of iliocaval compression syndrome. J Vasc Surg 2001;34:1061-1013.

12.

Heniford BT, Senler SO, Olsofka JM, Carrillo EH, Bergamini TM: May-Thurner syndrome: Management by endovascular surgical techniques. Ann Vasc Surg 1998;12:482-486. 

13.

Berger A, Jaffe JW, York TN: Iliac compression syndrome treated with stent placement. J Vasc Surg 1995;21:510-514. 

14.

Binskert CA, Schoch E, Stuckmann G, Largiader J, Wigger P, Schoepke W, Zollikofer: Treatment of pelvic venous spur (May-Thurner syndrome) with self-expanding metallic endoprostheses. Cardiovasc Intervent Radiol 1998;21:22-26. 

  Author Contacts

Kazuma Kishi
Division of Respiratory Diseases, Toranomon Hospital
2-2-2 Toranomon, Minato-ku
105-8470 Tokyo (Japan)
Tel. +81 3 3588 1111, Fax +81 3 3582 7068, E-Mail kazumak77@hotmail.com

  Article Information

Received: Received: April 17, 2001
Accepted after revision: August 4, 2001
Number of Print Pages : 4
Number of Figures : 3, Number of Tables : 0, Number of References : 14

  Publication Details

Respiration (International Review of Thoracic Diseases)
Founded 1944 as 'Schweizerische Zeitschrift für Tuberkulose und Pneumonologie' by E. Bachmann, M. Gilbert, F. Häberlin, W. Löffler, P. Steiner and E. Uehlinger, continued 1962-1967 as 'Medicina Thoracalis' as of 1968 as 'Respiration', H. Herzog (1962-1997)
Official Journal of the European Association for Bronchology and Interventional Pulmonology

Vol. 69, No. 3, Year 2002 (Cover Date: May-June 2002)

Journal Editor: C.T. Bolliger, Cape Town
ISSN: 0025-7931 (print), 1423-0356 (Online)

For additional information: http://www.karger.com/journals/res

  Drug Dosage / Copyright

Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in goverment regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher or, in the case of photocopying, direct payment of a specified fee to the Copyright Clearance Center.