The role of ultrasound diagnosis in vascular access (VA) can be divided into: (1) blood vessel evaluation before VA placement, (2) evaluation of immaturation, (3) daily VA management, and (4) diagnosis when trouble occurs. In the preoperative blood vessel evaluation of VA, not only the vascular diameter but also the properties of the arterial wall and the continuity of the vein are examined. We need to measure brachial arterial blood flow rate and resistance index (RI) at 2 weeks postoperatively, and use it for early detection and intervention of stenosis. In day-to-day VA management, monitoring based on physical findings is the main role. Ultrasound examination is used as surveillance, and brachial artery blood flow rate and RI are periodically measured if possible. If the brachial artery blood flow rate is less than 500 ml/min and RI 0.6 or more, the access function is judged to be degraded, and strict follow-up observation is required. Regarding puncture, ultrasonic-guided puncture, evaluation of a blood vessel before puncture, and confirmation of the needle point after puncture, etc., can be performed by ultrasonic examination. When VA trouble occurs, it is important to recognize that the symptoms change depending on the positional relationship between the puncture site and the stenosis. Generally, when brachial arterial blood flow rate is less than 350 ml/min and RI 0.67 or more, ultrasonic examination is carried out based on a suspicion of poor blood removal, risk of obstruction, or recirculation of VA, etc.

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Vascular access (VA) is essential for hemodialysis patients. The first VA produced at dialysis introduction, in particular, is the most important. Therefore, sufficient evaluation before VA production is necessary, and ultrasonic inspection is an effective method for that purpose. In the preoperative evaluation, observation by inspection and palpation is performed before ultrasonic examination. Evaluation by ultrasonic examination: The artery is measured for the presence or absence of stenosis and occlusion, and the inner diameter of the blood vessel and its patency are evaluated. The degree of calcification should also be observed. It is reported that VA is feasible if the arteriovenous diameter is 1.5 to 2.0 mm or more. For the vein, the entire vessel course and its continuity, vessel inner diameter, presence or absence of stenosis, position of a venous valve, and the like are observed. The anastomotic vein diameter is preferably 2.0 mm or more under avascularization. In addition, as with palpation, a search is made for a puncturable site. If the depth of the vessel is 5 mm or more, it becomes difficult to palpate and the difficulty level of the puncture increases, so we also observe the depth of the blood vessel at the expected puncture site. Conclusion: The final production site is judged comprehensively, taking into account factors other than vessel diameter such as age, puncture site, arteriovenous distance, and so on. Therefore, it is necessary to sufficiently discuss the results of the ultrasonic examination and the patient background with the operator for determination of the production site. If possible, it is desirable for the examiner and the operator to work together.

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Evaluation of vascular access ultrasound has been used for a long time. Vascular access ultrasound is described as an objective evaluation method of peripheral circulation disorders in the guideline published by the Japanese Society of Dialysis Therapy1). In vascular access ultrasound, B-mode images provide detailed tomographic images of the intima, the blood vessel wall, and the surrounding tissue, and the color Doppler method and pulse Doppler method can measure blood flow direction, blood flow velocity, and blood flow volume. Vascular access ultrasound is a minimally invasive examination method that can be used to evaluate the configuration and function of vascular access. This chapter, which focuses on arteriovenous fistula (AVF) and arteriovenous graft (AVG), describes the basic scanning method for vascular access ultrasound.

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The vascular access (VA) necessary for chronic hemodialysis can be assessed using VA ultrasonography. We discuss the assessment of stenosis and occlusion of arteriovenous fistula (AVF), arteriovenous graft (AVG), and subcutaneously fixed superficial artery by VA ultrasonography. B-mode can be used to assess the shunt vessel course and properties of the involved area in VA stenosis and occlusion. In addition to morphological assessment, functional assessment of AVF and AVG is possible with pulsed Doppler by using flow volume (BA-FV) in 1 minute calculated based on the flow pattern of the brachial artery and the resistance index (RI), and measuring these is very useful as an indicator in the functional monitoring of VA in all cases. Anastomotic stricture and venous (including hardening of venous valve) and stent site stenosis occur in AVF. In cases with occlusion, it is often caused by a thrombus, but it is important to identify the origin of the stenosis that is causing thrombus formation. Morphological assessment of AVG using VA ultrasonography consists of assessment of stenosis and occlusion occurring in the graft and assessment of stenosis that tends to occur at the venous outflow tract. Stenosis can occur at the cannulation site of a subcutaneously fixed superficial artery. Occlusion can also occur due to a thrombus or other cause. Subcutaneously fixed superficial artery is often complicated by damage to the arterial wall due to repeated punctures, and regular follow-up observation with VA ultrasonography is important.

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Complications after vascular access surgery include venous hypertension and dialysis access steal syndrome. Venous hypertension is venous stasis caused by impairment of vascular access perfusion due to various causes, and the development of collateral reflux further forms retrograde perfusion to the peripheral side, in which the venous perfusion is inhibited. In the ultrasound examination, findings such as decrease of brachial arterial blood flow rate or vascular graft flow rate in vascular access, stenosis or occlusion on the vein side, and excessive blood flow are obtained. Dialysis access steal syndrome is characterized by increased blood flow to the venous side of vascular access, and arteriovenous blood flow to the periphery of the upper extremity, which should be perfused, is stolen by an arteriovenous fistula, resulting in a condition that causes disorders and ischemic symptoms. Ultrasound examination can confirm findings such as excess blood flow and stenosis on the side of the artery or obstruction. It should be noted, however, that venous hypertension and dialysis access steal syndrome are conditions caused by an imbalance of arteriovenous perfusion in vascular access and do not exhibit certain characteristic findings. Therefore, overall evaluation including symptoms is necessary for each case, and it is important to grasp the disease state based on evaluation of the morphology and blood flow by conducting a wider range of observations during the ultrasound examination.

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Ultrasound (US) vascular imaging is essential to ensure successful management and maintenance of hemodialysis (HD) vascular access (VA). It is also a valuable adjunct in assessing certain VA-related complications as below. 1) Cannulation Inability: Adequate implementation of repeatable and safe cannulation of VA is required both in the clinical practice of HD treatment and for establishment of the patient-practitioner relationship. US imaging facilitates identification of the cause of inaccessibility mainly attributable to vascular structural obstructions in the cannulation segment. It also enables us to provide a resolvable approach by identifying an alternative cannulable segment. 2) Aneurysm/Pseudoaneurysm Formation: Prompt detection of aneurysmal instability and impending rupture is crucial for the potential urgent procedure. Both rapid aneurysmal enlargement in the short term and overstretched shiny appearance of skin overlying the aneurysm are the primary predictors indicating the occurrence of these serious conditions. US imaging elucidates sequential morphological alteration of the aneurysm such as its expansion and contour transformation. Additionally, it is useful for identifying the fundamental vascular stenosis in aneurysmal formation. 3) Infectious Lesion: Infectious VA-related complications remain a significant cause of morbidity and mortality in HD patients. A combined approach based on both identification of the infectious lesion and detection of the systemic inflammatory reaction with infectious findings is indispensable for the precise diagnosis of VA infection. The existence of a localized hypoechoic area detected by US consistent with the erythema is a reasonable and supportable manifestation of the infectious lesion. In conclusion, recent advances in comprehensive management of VA-related complications have led to an increased utilization of US imaging as an adjunctive assessment tool. In the diagnostic process employing the herein-described advantageous US approach, careful ascertainment of the compatibility between imaged manifestations and clinical symptoms ensures accurate comprehension of the pathophysiology.

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Portosystemic encephalopathy is often overlooked, being treated as a decrease in cognitive function in elderly patients. We herein report a case of traumatic splenic rupture with a portosystemic shunt. We resected the spleen and resolved the occlusion of the portosystemic shunt via intraoperative ultrasound. An 84-year-old woman was transported to the emergency room with loss of consciousness. She had fallen and fractured a rib 11 days earlier. Emergency splenic resection was performed following a diagnosis of late-onset splenic rupture and intra-abdominal bleeding. Before the surgery, we confirmed the splenic renal shunt and diagnosed her with portosystemic encephalopathy. We confirmed portal reflux in the left branch of the portal vein with intraoperative ultrasonography. The splenic renal shunt was ligated due to antegrade portal blood flow when the shunt became occluded. Because of the emergent nature of the surgery, preoperative inspections were inadequate. We carefully evaluated whether or not we could resolve the occlusion of the splenic renal shunt via intraoperative ultrasound. After surgery, the portal vein blood flow remained antegrade, and her level of consciousness rapidly improved. Emergency occlusion of the portosystemic shunt was therefore deemed effective. Because intraoperative ultrasound can be used to monitor the blood flow in real time, we successfully resolved the occlusion of the splenic renal shunt effectively and safely. We therefore considered that intraoperative ultrasonography was useful.

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The patient was a 26-year-old pregnant woman, gravida 5, para 2 (3 spontaneous abortions, 1 Caesarean section, 1 Caesarean section after transvaginal delivery). Although Cesarean section scarred pregnancy was previously suspected at 9 weeks of gestation in a private clinic, a final decision was not made. She subsequently underwent routine pregnancy checkups. At 19 weeks’ gestation, she was referred to our perinatal center due to oligohydramnios. Although she did not have any symptoms, ultrasound revealed that the placenta was attached on the previous Caesarean section scar. Although there were no findings of outflow of the amniotic fluid including the echo-free space in the abdominal cavity and rupture of membrane, the amniotic fluid cavity was almost absent. Since fetal morphological assessment was difficult, amniotic fluid injection was performed after admission to the hospital. Fetal assessment was then attempted, which showed a bell-shaped thorax, absence of gastric fluid, and absence of the bilateral kidneys and the bladder. Moreover, the placenta was adhered to the whole Caesarean section scar and bulged. A closed small uterine body was also found at the uterine fundus. Therefore, diagnoses of Cesarean scar pregnancy and Potter syndrome were made. Considering the risk of uterine rupture, we decided to perform induced abortion after consulting the patient and her family. Because she had a strong desire for uterine preservation, wedge resection of scarred pregnancy after Caesarean section and wound repair were performed. Conclusion: Amniotic fluid injection successfully led to a diagnosis of previous Caesarean scarred pregnancy with oligohydramnios due to Potter syndrome. This case suggests that ultrasound evaluation of the previous Caesarean scar in early pregnancy is important for safe management of the pregnancy.

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Imperforate hymen is a relatively rare congenital anomaly, but it is the most common anomaly of the female reproductive tract. Diagnosing imperforate hymen is relatively easy for obstetricians and gynecologists. However, patients with imperforate hymen often visit primary physicians, emergency physicians, or pediatricians due to abdominal pain, urinary distention, or lower back pain, and it is difficult to diagnose imperforate hymen using only a description of the symptoms and palpation. The present case report details the transabdominal ultrasonographic diagnosis of imperforate hymen in an 11-year-old female with a 15-day history of increasing abdominal pain, lower back pain, and slight pain during urination. The three transabdominal ultrasound findings essential for the accurate diagnosis of imperforate hymen were: vaginal dilation, anterosuperior location of the uterus, and a fluid connection sign between the vagina and the uterus. We propose that primary physicians can easily visualize the uterus during abdominal ultrasonography by ensuring that the bladder is full, using graded compression, and observing a fixed position. Primary physicians can achieve an early diagnosis of vaginal closure by confirming the presence of the three abdominal ultrasonographic findings, in combination with history taking and palpation.

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