Venous thrombosis

Introduction Venous thrombosis (phlebothrombosis) is caused by various causes of lowering the pressure of the venous return of the calf, leading to thrombosis. Most occur in patients with lower extremities or pelvic and abdominal surgery, severe trauma, acute infection, pregnancy, malignant tumors, heart disease. Reduced pressure on the calf venous return caused by various reasons, increased blood viscosity, increased platelets and increased blood coagulation. When the vascular endothelium is slightly damaged, it can cause platelets to adhere to form platelet thrombus, followed by fibrin deposition and thrombosis. Increase, and the vascular cavity is occluded.

Cause

(1) Causes of the disease

The disease is divided into two types: infectious and non-infective.

Infectious people are more common in acute infection, childbirth, pelvic or abdominal surgery, non-infectious people are caused by blood stasis, and more common in the posterior vein of the calf.

(two) pathogenesis

The calf venous return pressure is reduced due to various reasons, blood viscosity and platelet increase, and blood coagulation is increased. When the blood vessel is slightly damaged, it can cause platelets to adhere to the local thrombus, and then fibrin deposition causes the thrombus to increase, leading to occlusion of the lumen. Even spread to nearby or distant veins.

an examination

Related inspection

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1. Ask if there is any history of trauma, time of injury and treatment, history of long-term bed rest, surgery, pregnancy, childbirth and oral contraceptives, history of repeated venipuncture or intravenous infusion catheter. Whether the symptoms and the disease period are consistent, the location and development of the onset, the nature of the pain, whether there is fever, swelling and pain of the affected limb.

2. During local examination, attention should be paid to the presence or absence of tenderness, tenderness, and swelling of the affected limb (the circumference should be accurately measured on the thickest plane with a tape measure and compared with the same plane on the healthy side). And temperature (measured by the skin temperature measurer compared to the contralateral side), whether there is a change in the distal pulse of the limb, whether there is a tender cord on the body surface, whether there is an infected lesion and the foot boots Nutritional changes in the area, such as desquamation, itching, pigmentation, eczema and ulcer formation.

3. When the diagnosis is difficult or to determine the extent of the lesion, feasible ultrasound, pulse Doppler spectrum examination, venography (can effectively determine the presence or absence of thrombosis, thrombus location, extent, morphology and collateral circulation).

4. Intravenous pressure measurement, foot venous puncture, needle pressure sensor or scaled transparent plastic tube (filled with heparin-physiological saline solution) to measure venous pressure, normal pressure is generally 12.7kPa (130cmH20), for ankle joint extension When flexion is active, the gastrocnemius contraction, the pressure drops significantly, generally can be reduced to 5.9 kPa (60 cmH20), the pressure rises after stopping the activity, and the recovery time exceeds 20 s. There are thrombosis and occlusion in the main vein. The pressure at rest or activity is significantly increased, and the recovery time is generally no more than 12 s.

Differential diagnosis

Symptoms of venous thrombosis need to be identified as follows.

The diagnosis of acute venous thrombosis of the lower extremities is often not difficult. Postpartum, fracture and trauma, post-operative patients, if there is limb pain, swelling, superficial venous engorgement, should consider the possibility of this disease. When the diagnosis is difficult, venous pressure measurement and venography can be performed. Radionuclide venography of the lower extremity is helpful for diagnosis and safer. Doppler ultrasound blood flow detector can be used to check the thrombosis of the external and femoral veins, and the examination of venous thrombosis in deep muscle or pelvic cavity is not accurate. The 125I-labeled human fibrinogen test is most valuable for the diagnosis of deep muscle venous thrombosis in deep muscles. If it can be continuously examined for several days, the accuracy rate can reach more than 85%. If the pain is not significant, and the swelling of the limb is obvious, attention should be paid to the identification of lymphedema. The latter has a slow course of disease, thickening of the skin, and no superficial varices. After the bed was raised, the swelling subsided was not obvious.

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