Ultrasound of abdominal and peripheral veins

Expert consensus on common clinical problems

The superficial organ and peripheral vascular ultrasound Professional Committee of the Chinese society of ultrasonic medical engineering, the vascular ultrasound Professional Committee of the stroke prevention and treatment engineering expert committee of the National Health Commission, and the brain and neck vascular ultrasound Professional Committee of the Chinese society of ultrasonic medical engineering made reference to the latest literature at home and abroad, discussed repeatedly, and finally reached three consensuses in combination with China's national conditions, They are "expert consensus on some common clinical problems of abdominal and peripheral venous ultrasound", "expert consensus on some problems of cervical arterial ultrasound" and "expert consensus on some common clinical problems of abdominal and limb arterial ultrasound diagnosis and treatment". Today, I want to share with you the expert consensus on some common clinical problems of abdominal and peripheral venous ultrasound. I hope it can help you with vascular ultrasound.

Implementation process and thought chart of ultrasound examination for patients with acute and critical dyspneaThis thought map covers lung ultrasound, cardiac ultrasound, inferior vena cava ultrasound, and lower extremity vein ultrasound. Recommended collection.

Suggestions on ultrasonic treatment of abdominal and peripheral venous vessels

Opinion 1: recommended position for ultrasonic examination of venous reflux in lower limbs

The recommended position is head high and feet low (it is recommended to use electric examination table), that is, the head side of the examination table is higher than the foot side, and the included angle with the ground is about 30 °. Standing position or sitting position can be selected under limited conditions, and prone position is not recommended to evaluate venous reflux of lower limbs.

Opinion 2: applicability of Valsalva (Valsalva action)

Valsalva maneuver is mainly used to evaluate the function of saphenous femoral vein valve and proximal femoral vein valve, which is not suitable for the evaluation of distal venous reflux of lower limbs. To evaluate the function of the distal venous valve (below the popliteal vein level), the method of squeezing the distal limb can be used.

If the patient cannot cooperate to complete the autonomous and effective Valsalva maneuver, especially the elderly and patients with unclear consciousness, regular compression of the patient's lower abdomen can be used to achieve the effect similar to the Valsalva maneuver.

Opinion 3: ultrasound evaluation of localized stenosis and dilatation of jugular vein and lengthy jugular valve

Clinically, it is common for patients to diagnose with "neck mass after cough", and local widening of internal jugular vein, or inadvertently found that the local diameter of internal jugular vein is too small, or long venous valve flutter can be seen in internal jugular vein, which are mostly physiological variations without clinical significance. Therefore, when the above three conditions are detected by ultrasound, patients without clinical symptoms, hemodynamic changes and related primary diseases can be prompted without diagnosis.

In case of unexplained headache, tinnitus and other symptoms, the possibility of head and neck venous reflux disorder caused by organic lesions of internal jugular vein should be considered. Studies have confirmed that intracranial venous sinus thrombosis is related to ipsilateral internal jugular vein stenosis; Headache in some patients is related to abnormal ipsilateral venous reflux caused by long jugular valves, resulting in structural changes such as tortuous expansion of intracranial veins or relative expansion of venous sinuses.

Opinion 4: if the vein of lower limbs is not clearly displayed by the linear array probe, the next step of examination and diagnosis should be carried out

Ultrasonic examination of lower limb veins usually adopts the linear array probe vein examination mode, and the center frequency is generally 5~7.5 MHz. However, for patients with obesity and severe edema of lower limbs, the convex array probe should be combined (pay attention to the adjustment and setting of relevant examination conditions of the instrument). If gray-scale ultrasound is still difficult to display, when the deep vein is not clearly displayed, color Doppler blood flow imaging mode should be used to check, pay attention to adjusting the blood flow velocity and gain, improve the low-speed venous blood flow imaging, and cooperate with the squeezing action of the distal limb to accurately judge the patency of venous blood flow

Opinion 5: common causes of "cloud like" blood flow imaging in venous ultrasound examination.

The main reasons for "cloud like" venous blood flow imaging are the improvement of the resolution of ultrasonic instruments and the slow venous blood reflux, especially in the venous sinus at the root of the venous valve.

"Cloud like" blood flow cannot be considered as prethrombotic. First of all, there is no concept of prethrombotic in clinic. The three basic factors of venous thrombosis are venous blood flow retardation, intimal injury and hypercoagulability. Slow blood flow does not necessarily lead to thrombosis. In case of thrombosis, ultrasound can observe the characteristics of low echo filling in the venous cavity, and the probe compression examination shows that the venous cavity cannot be completely closed. At the same time, we should pay attention to whether the patient has clinical related manifestations such as increased D-dimer, so as to improve the diagnostic accuracy of venous thrombosis.

Opinion 6: after the central venous catheter (PICC) is inserted through the peripheral vein, there is no blood flow in the superficial vein and there is solid hypoechoic formation, which guides the clinical treatment.

Catheter related venous thrombosis is divided into deep venous thrombosis, superficial thrombophlebitis, asymptomatic thrombosis and thrombotic catheter failure. Ultrasound is the preferred examination method. The current guidelines do not recommend routine catheter removal after thrombosis, unless the patient no longer needs the catheter, the catheter function is lost, the location is abnormal, or combined with infection, and the catheter can be removed after the thrombosis is stable.

When superficial vein thrombosis occurs, ultrasound should evaluate the scope of the thrombosis (whether it involves axillary vein and its proximal deep vein), and then evaluate whether the catheter location is normal and the patency of the catheter to guide clinical treatment. When it is difficult to observe thrombus in innominate vein and vena cava by ultrasound, it can be combined with CT venography (CTV) or magnetic resonance venography (MRV). For patients who are highly dependent on catheters and have difficulty in establishing new venous pathways, if deep venous thrombosis occurs, it is necessary to weigh the value of catheters and the potential risk of thrombosis. Therefore, for venous thrombosis after PICC, in addition to evaluating the above image indicators, whether the catheter is removed or not needs to be comprehensively considered in combination with the patient's own venous thromboembolism (VTE) risk assessment, blood routine, coagulation function and other laboratory indicators, as well as the risk / benefit ratio.

Opinion 7: whether nutcracker syndrome is equivalent to "Nutcracker Phenomenon", ultrasonic tips and diagnostic criteria.

"Nutcracker Syndrome" is not equivalent to "Nutcracker Phenomenon". Nutcracker syndrome refers to a series of clinical syndromes such as hematuria or orthostatic proteinuria, abdominal pain and varicocele caused by the compression of the left renal vein, which is a clinical diagnosis. The "Nutcracker Phenomenon" refers to the phenomenon that the lumen of the left renal vein between the abdominal aorta and the superior mesenteric artery is narrow and the distal lumen is dilated, without or with clinical symptoms, which is a morphological diagnosis. Nutcracker phenomenon can also exist in normal people, and the concept is broader. In the past, there was no difference between nutcracker phenomenon and nutcracker syndrome, resulting in the false positive of nutcracker syndrome suggested by ultrasound. Therefore, the expert group believes that the direct diagnosis of "Nutcracker Syndrome" by ultrasound is inappropriate and should suggest that nutcracker phenomenon is more accurate. 

Nutcracker phenomenon can be divided into two types: (1) anterior type, the pressure of left renal vein between abdominal aorta and superior mesenteric artery is the most common; (2) In the posterior type, the left renal vein runs behind or around the abdominal aorta, and the compression stenosis between the abdominal aorta and the spine is rare, accounting for about 0.8% - 7.1%.

The ultrasonic diagnostic criteria for nutcracker phenomenon in the vascular ultrasound guidelines of the ultrasound physicians branch of the Chinese Medical Association are: (1) gray scale ultrasound: the gap between the abdominal aorta and the superior mesenteric artery is significantly smaller, and the left renal vein is significantly compressed; The distal end of the left renal vein was significantly dilated, and the internal diameter of the dilated segment of the left renal vein was more than 3 times that of the stenosis, and more than 4 times that of the spinal column 20 minutes after extension; (2) CDFI and PW examination showed that the blood flow velocity at the dilated part of the left renal vein decreased, while the venous flow velocity at the compressed part increased, and the renal vein at the distal end of the stenosis was dilated, and the frequency spectrum was low, flat or disappeared.

Opinion 8: precautions for ultrasound evaluation of varicocele.

Varicocele can usually be diagnosed by clinical palpation, but when the nature of the touched mass is unknown, the mass is painful or tender, and infertility, the existence of varicocele should be highly suspected, which can be further evaluated by ultrasound.

Ultrasound evaluation of varicocele is affected by the examination position and whether to perform Valsalva maneuver. The expert group suggests that the following issues should be paid attention to in the evaluation of varicocele:

1. The examinee should take a standing position, evaluate and describe under resting and Valsalva motion respectively, and both sides should be examined by gray-scale and color Doppler, as well as spectral Doppler analysis.

2. Measure the maximum internal diameter of spermatic cord vein under the action of Valsalva in standing position, and indicate the specific position of the measurement point relative to spermatic cord or testis (such as groin area, above testicle, testicular level). Recommended ultrasonic diagnostic criteria for varicocele (one of the following is sufficient):

(1) The patient is in a standing position, the internal diameter of spermatic vein at rest is ≥ 2mm, and Valsalva maneuver is accompanied by positive reflux [20]; (2) The internal diameter of spermatic vein is ≥ 3mm when the patient is in standing position and Vahl's action; (3) In addition, the reflux time can also be used as the main parameter to evaluate the reflux of spermatic vein. Varicocele can be diagnosed if the duration of reflux is more than 2S during Valsalva maneuver; ≥ 1s, it can be diagnosed as subclinical varicocele< 1s, physiological.

3. Varicocele is common on the left side, and some may be related to nutcracker syndrome. For patients with isolated right varicocele or acute varicocele, the examination can be extended to the retroperitoneal area to judge whether there is space occupying lesions.

4. Varicocele is related to testicular function. Infertile patients need to evaluate testicular volume (length) at the same time × wide × thick × 0.71)。

5. When the patient's standing position is inconvenient, the measurement can be carried out by adding VaR's action in the supine position.

Opinion 9: the evaluation method of central venous pressure by ultrasonic detection of internal jugular vein.

Central venous pressure refers to the pressure of superior and inferior vena cava and right atrium. The normal value is 412 C M H 2O, which can reflect the systemic blood volume. When the normal person is in the semi recumbent position of 30 ° ~45 °, the anterior and posterior diameter of the right internal jugular vein (IJV) from the distal end to the proximal end gradually shrinks, and suddenly expands near the upper mouth of the thorax to form a inflection point, that is, the collapse point, which moves up and down with breathing. CVP is the vertical distance (Fig. 3C) between the collapse point of IJV on the right side of the subject at the end of exhalation (Fig. 3a) and the body surface projection point (Fig. 3b) in the center of the right atrium measured by ultrasound. The CVP value measured by this method is highly correlated with the value measured by central venous catheter (r=0.93). Taking 10.75cm as the threshold, the sensitivity and specificity of diagnosing CVP increase are 96.9% and 87.1%, and the repeatability is good, which is conducive to clinical promotion..

Chinese Journal of ultrasound medicine, November 2020, Volume 36, issue 11.