Pattern and Distribution of Thrombi in

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cases with deep vein thrombosis, and the calf in 40% of the cases. Isolated calf ... clearly shown that the soleal sinuses are the most com- mon site for thrombi to ...
Pattern and Distribution of Thrombi in Acute Venous Thrombosis Arie Markel, MD; Richard A. Manzo, CCVT; Robert O. \s=b\ The

location and extent of thrombosis in the deep venous

system will determine immediate and long-term outcome. During the past 3 years, we have studied by duplex scanning

833 patients with suspected deep vein thrombosis. In this group, 209 patients (25%) had a positive study. The findings relative to location and extent of involvement are as follows. (1) The right leg was involved in 35% of patients, the left leg in 48%. Bilateral involvement was noted in 17%. (2) The veins most frequently affected by deep vein thrombosis were as follows: superficial femoral in 74%, popliteal in 73%, common femoral in 58%, posterior tibial in 40%, deep femoral in 29%, greater saphenous in 19%, and the inferior vena cava in 2%; multisegment involvement was common. (3) Total occlusion was present in 82% of the patients with deep vein thrombosis, and partial occlusion in 18%. (4) Isolated occlusion of single veins was uncommon. (5) The proximal (above-knee) area was involved in 95% of the cases with deep vein thrombosis, and the calf in 40% of the cases. Isolated calf deep vein thrombosis was found in 6% of the cases with right leg involvement and in 3% for the left. (6) Total leg involvement (iliocaval, femoropopliteal, and calf) occurred in 10% of the patients. Our data confirm the fallibility of the clinical diagnosis of deep vein thrombosis. The frequent involvement of both limbs stresses the importance of not examining just the symptomatic limb. Proximal venous thrombosis (popliteal to inferior vena cava) is much more common than isolated calf vein thrombosis as a cause for symptoms and the referral for study.

(Arch Surg. 1992;127:305-309)

deep vein thrombosis (DVT) may develop any Acutelevel of the deep system from the soleal si¬ in the calf the iliac veins and inferior at

venous

k

to

nuses

vena cava.

Knowledge concerning the location and extent of involve¬

ment comes from two types of studies. Iodine 125-labeled fibrinogen has been used to document the development

of the disease from its earliest stages. This method has clearly shown that the soleal sinuses are the most com-

Accepted From the

for publication September 7, 1991. Department of Surgery, University of Washington, Se-

attle. Presented at the Third Annual Meeting of the American Venous Forum, Fort Lauderdale, Fla, February 20-22, 1991. Reprint requests to Vascular Surgery Section, Department of Surgery, RF-25, University of Washington, Seattle, WA 98195 (Dr

Strandness).

Bergelin, MS;

D.

Eugene Strandness, Jr,

MD

site for thrombi to occur early.1-2 If untreated, most of these thrombi will spontaneously lyse, but up to 20% will propagate to involve the tibial and popliteal veins.1-3 Studies that have focused primarily on patients who present with symptoms and signs have shown a dramat¬ ically different pattern of distribution. These have basi¬ cally involved the use of venography and in more recent years impedance plethysmography. The latter method will only detect proximal venous thrombi (popliteal to il¬ iac level), and thus, cannot provide information on the status of the veins below the knee.4 Venography will de¬ tect thrombi at all levels, and studies done by this method have shown a significant incidence of proximal venous thrombi, either alone or in combination with involvement below the knee.5"7 It is generally assumed that the major danger of serious and occasionally fatal pulmonary emboli occurs when the iliofemoral venous segment is involved.8-9 It also seems that thrombi forming at lower levels pose less of a risk, with those occurring below the knee posing little risk.3 One of the major unanswered questions in this field relates to the prospect of a thrombotic episode leading to the development of the postthrombotic syndrome. While it is known that the two sequelae of acute DVT are resid¬ ual obstruction and subsequent valvular damage, the likelihood that this will occur for specific venous segment occlusions remains unclear. For any diagnostic method to be of value, it will be nec¬ essary to document accurately the location and extent of the initial thrombotic event. While venography remains the best method for anatomic localization, it is not ideal, for reasons that are well understood. The recent applica¬ tion of duplex ultrasonic scanning to this problem has provided a new opportunity for clinical research into this mon

common

problem.10

The purpose of this article is to present our findings in 833 patients who presented to our vascular laboratory with symptoms and signs suggesting the diagnosis of acute DVT. All patients were studied by ultrasonic duplex scanning. Of this group, 209 patients were found to have thrombosis of their deep veins as the cause of their problems. The findings in this group of patients will be presented. PATIENTS AND METHODS December 1986, all patients referred to the vascu¬ Starting in lar laboratory to rule out acute DVT had a duplex scanning study

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done. A total of 833 patients with a suspected diagnosis of DVT were studied up to March 1990. From this group a total of 209 patients (25%) had a positive study by duplex scanning. These data are the basis for the prevalence analysis reported herein. Venous duplex examination was performed (Advanced Tech¬ nology Laboratories Ultramark 8 or 9, Bothell, Wash) with the patient at 10° to 15° in the reverse Trendelenburg position. The common iliac and external iliac veins were imaged with a 3- or 5-MHz transducer. The common femoral, superficial femoral, deep femoral, popliteal, and greater saphenous veins were im¬ aged with a 5- to 7.5-MHz transducer. The superficial femoral vein was examined at three locations in the thigh: distal to the bifurcation of the common femoral vein, in the midthigh region, and at the entrance to the adductor canal. The popliteal vein was examined with the patient prone. The posterior tibial veins were evaluated in the lower half of the leg with the 10-MHz trans¬ ducer. Pulsed Doppler venous signals were obtained for each of the examined veins with a 5-MHz transducer. The inferior vena cava was also examined, using a 3-MHz transducer. No attempts were made to image routinely either the anterior tibial veins or the peroneal veins. Imaging of the anterior tibial and peroneal veins is difficult with standard duplex scanning. Perhaps with the availability of color Doppler, this may become more feasible. At the time of these studies, color was not being used routinely in our laboratory. All veins were examined in the longitudinal scan plane for the presence of thrombi. The pulsed Doppler was used to determine the presence of spontaneous flow, phasicity of flow with respi¬ ration, augmentation of flow with distal compression, augmen¬ tation of flow with release of proximal compression or release of Valsalva, and reversal of flow (reflux) with proximal compres¬ sion or Valsalva. The veins were then examined in the transverse scan plane for compressibility with probe pressure. The results of the duplex study were placed into the following categories: normal (negative), abnormal (positive), or inconclu¬ sive. The duplex scan was considered positive for DVT in a par¬ ticular venous segment when some or all of the following features were present: a thrombus was visualized, the vein was not completely compressible, flow was absent, and phasicity of venous flow with respiration was absent. There were two exceptions to these criteria. First, compressibility could not be used for the inferior vena cava, common iliac, or superficial femoral vein as it enters Hunter's canal. In most patients, the veins in these locations cannot be compressed consistently even when they are normal. Second, absence of spontaneous flow in the posterior tibial veins is too variable to be used as a criterion. For the posterior tibial veins, a positive test was absence of flow after distal augmentation. If the study was not clearly shown to be normal or abnormal, it was considered inconclusive. If the vein did not have detectable flow at the site of the thrombus, it was considered totally occluded. Partial obstruction was noted if flow could be detected around a thrombus. The findings were summarized for each one of the veins and for the different segments in each leg. Results of the duplex scanning for each one of the legs were also included. Total obstruction in the examined leg was defined as the presence of a completely occluding thrombus in one or more segments of that limb; if only partially occluding thrombi were present, a diagnosis of partial obstruction was made. The term above-knee includes the popliteal vein and proximal segments; below-knee refers to involvement of the posterior tibial vein. The data were stored on a microcomputer using the SPSS data entry program. Analysis of the data was done using the SPSS/PC statistical package. Comparison of mean ages was done by Stu¬ dent's í test. Point estimates of prevalence of DVT were evalu¬ ated using two-tailed confidence intervals.

RESULTS A total of 833 patients were referred for study to rule out the presence of acute DVT. In this group were 52 patients with chronic venous symptoms who suffered an acute

Table

1.—Age and Sex of Patients in Study* Total Population Patients With DVT Age,

Sex

No. (%)

Mean ± SD

Range

53±18

7-89

M

394(47) F 439(53) Total 833 (100) *DVT indicates

Age, y

y

53 ±18

53 ±18

deep

No. (%)

113(54) 4-100 96(46) 4-100 209(100)

Mean ± SD

Range

52±18

10-89

52 ±19

4-88 4-89

52 ±18

vein thrombosis.

Table 2. —Relative Prevalence of Total and Partial Obstruction in Studied Patients With DVT (n 209)* =

Total

Leg

Obstruction,

No. (%)

Partial Obstruction, No. (%)

Total No.

R

87 (81)

21 (19)

108

L

108(79)

28(21)

136

*DVT indicates deep vein thrombosis. Percentages refer to the total number of positive cases for each leg (includes patients with bilateral DVT).

episode, and 781 patients who presented for the first time with venous problems. From the 833 patients, 209 (25%) had a positive study by duplex scanning; 588 (71%) of the patients had a negative study; and in 36 patients (4%), the

study was inconclusive.

The age and sex of the patients are given in Table 1. No differences were noted in the mean age of the patients with a positive and negative duplex scan. Distribution by sex showed a slight preponderance of women. On the other hand, a greater number of male patients had a pos¬ itive duplex study (P