NHÂN CA BUDD-CHIARI SYNDROME tại MEDIC

BUDD-CHIARI SYNDROME [BCS]

@ MEDIC:
Female patient 25yo from Vinh long province had been diagnosed hepatosplenomegaly with unknown cause from 2004 in many hospitals. Ultrasound detected IVC underdiaphramatic stenosis, big caudate lobe and big spleen and liver with coase pattern due to regenerative nodules. 

MDCT 64 disclosed a web into IVC and collateral circulations and hepatosplenomegaly. So it was a case of  BUDD-CHIARI Syndrome due to MOVC (membraneous obtruction of inferior vena cava). The female patient remains well after an bridging operation to connect subrenal IVC to right subclavian vein.

 

 

@ BUDD-CHIARI SYNDROME [BCS]: ULTRASOUND

 



An enlarged caudate lobe, hepatomegaly, lack of visualization of the hepatic veins, a compressed IVC, enlarged intrahepatic collaterals, splenomegaly, and ascites are conventional sonographic findings in patients with BCS. In some instances, an enlarged caudate lobe vein ( > 3 mm) can be seen draining directly into the IVC, a spider-web appearance of hepatic veins or replacement of the hepatic vein by a fibrous, echogenic cord. Ultrasound may also show that the stenotic IVC, especially in the intrahepatic segment, is associated with an enlarged caudate lobe. In some chronic cases, large regenerative nodules that may simulate carcinoma may be present. On Doppler evaluation, patients with BCS may present with enlarged hepatic veins with no flow signal or with reversed flow. The identifcation of collateral vessels with drainage into the subcapsular or intercostal veins is a highly sensitive and specifc feature for the diagnosis of BCS.

See CDUS in Budd-Chiari Syndrome
và   SIÊU ÂM BUDD-CHIARI SYNDROME

TẮC LỆ ĐẠO Ở THAI NHI

BS JASMINE THANH XUÂN
Khoa Siêu âm Medic TPHCM.

- Thuật ngữ : Dacryocystocele: tắc lệ đạo.
- Lệ đạo là hệ thống đường dẫn nước mắt đi từ vùng hồ lệ đến khe mũi dưới, bao gồm: điểm lệ, lệ quản, túi lệ, ống lệ mũi. Bình thường, nước mắt được tiết ra từ các tuyến lệ, sau khi đã làm ướt bề mặt nhãn cầu, phần còn lại sẽ đổ vào điểm lệ, vào lệ quản, túi lệ, qua ống lệ mũi và đổ ra ngách mũi phía dưới. Khi có bệnh lý ở đường lệ, nước mắt sẽ bị ứ đọng và gây chảy nước mắt, đôi khi kèm theo mủ và nhầy.
- Lệ đạo ở thai nhi vốn là một ống đặc, chỉ trở nên rỗng ở những tháng cuối. Khi sinh ra, đa số trẻ có lệ đạo đã thông suốt để thực hiện chức năng dẫn lưu nước mắt; nhưng ở một số trẻ, quá trình tạo ống vẫn tiếp tục sau đó 1-2 tuần.

Tuyến lệ bình thường và hình Tắc lệ đạo (sơ đồ). Nguồn : Visual Art @ 2007. The University of Texas. M.D. Anderson Cancer Center.

- Tắc lệ đạo có thể phát hiện được trong thời kỳ mang thai bằng siêu âm khảo sát vùng quanh nhãn cầu.
- Khảo sát hình thái học thai nhi ở 3 tháng giữa cần thiết phải cắt ngang qua hai nhãn cầu, cho phép đánh giá nhãn cầu xa nhau, gần nhau… gợi ý các bất thường về nhiễm sắc thể.
- Chiều dài đường nối liền hai thuỷ tinh thể (tính bằng đơn vị mm) sẽ tương ứng với tuổi thai tính theo tuần.
- Ví dụ : Thai nhi 22 tuần , đường nối ngang tâm hai thuỷ tinh thể sẽ tương ứng 22mm.
- Một số máy siêu âm chuyên về khảo sát thai sẽ cho biết tuổi thai nhi (tính bằng tuần) khi đo đường kính bờ ngoài hai hốc mắt (OOD = Outer Orbicular Diameter).

Minh hoạ : tuổi thai 22 tuần 1 ngày được tính bằng cách đo OOD.

 

Hình minh hoạ : đường cắt khảo sát quanh hốc mắt phải thai nhi, cho thấy một cấu trúc dạng nang echo trống giống nhãn cầu nhưng kích thước nhỏ hơn, gợi ý túi dịch ( túi lệ) trong tắc lệ đạo thai nhi.

Hình tái tạo 3D: trên thai nhi này cho thấy rõ nét dưới khoé mắt phải có cấu trúc giống hình giọt nước mắt lớn (gợi ý tắc túi lệ thai nhi).

- Thai nhi được khảo sát sau đó 6 tuần, không còn thấy hình ảnh túi echo trống nằm sát dưới nhãn cầu phải nữa. Điều này cho thấy lệ đạo thai nhi là một ống đặc, và rỗng ở những tháng cuối. Do đó nước mắt đã được lưu thông xuống ngách mũi dưới.

Hình minh hoạ một trường hợp khác cho thấy sau sanh có hình ảnh tắc lệ đạo bên Trái.

Nguồn : Internet.

- Tóm lại , tắc lệ đạo bẩm sinh có thể phát hiện từ trong thời kỳ bào thai bằng cách siêu âm khảo sát kỹ hai nhãn cầu. Đường cắt ngang hai nhãn cầu để tính tuổi thai cho thấy cấu trúc dạng nang echo trống sát dưới nhãn cầu gợi ý có tắc lệ đạo. Tắc có thể thoáng qua ở những tháng đầu thai kỳ, sau đó sẽ tự biến mất, hoặc kéo dài đến sau sanh 1- 2 tuần hay nhiều tháng sau sanh.

ARFI QUANTIFICATION in SELECTED LIVER SEGMENTS

SIÊU ÂM CHẨN ĐOÁN VIÊM TÚI MẬT CẤP

Abstract

Purpose: To update previously summarized estimates of diagnostic accuracy for acute cholecystitis and to obtain summary estimates for more recently introduced modalities.

Materials and Methods: A systematic search was performed in MEDLINE, EMBASE, Cochrane Library, and CINAHL databases up to March 2011 to identify studies about evaluation of imaging modalities in patients who were suspected of having acute cholecystitis. Inclusion criteria were explicit criteria for a positive test result, surgery and/or follow-up as the reference standard, and sufficient data to construct a 2 × 2 table. Studies about evaluation of predominantly acalculous cholecystitis in intensive care unit patients were excluded. Bivariate random-effects modeling was used to obtain summary estimates of sensitivity and specificity.

Results: Fifty-seven studies were included, with evaluation of 5859 patients. Sensitivity of cholescintigraphy (96%; 95% confidence interval [CI]: 94%, 97%) was significantly higher than sensitivity of ultrasonography (US) (81%; 95% CI: 75%, 87%) and magnetic resonance (MR) imaging (85%; 95% CI: 66%, 95%). There were no significant differences in specificity among cholescintigraphy (90%; 95% CI: 86%, 93%), US (83%; 95% CI: 74%, 89%) and MR imaging (81%; 95% CI: 69%, 90%). Only one study about evaluation of computed tomography (CT) met the inclusion criteria; the reported sensitivity was 94% (95% CI: 73%, 99%) at a specificity of 59% (95% CI: 42%, 74%).

Conclusion: Cholescintigraphy has the highest diagnostic accuracy of all imaging modalities in detection of acute cholecystitis. The diagnostic accuracy of US has a substantial margin of error, comparable to that of MR imaging, while CT is still underevaluated.

© RSNA, 2012



SUY GIÁP BẨM SINH

 Abstract

OBJECTIVE. The purpose of this study was to retrospectively evaluate the use of sonography as the primary imaging modality for congenital hypothyroidism (CH).

MATERIALS AND METHODS. From our regional registry, we reviewed the cases of patients for whom either sonography or ^99mTc-pertechnetate scanning was performed for CH between 2003 and 2010. Ultrasound studies were reviewed for presence, size, echotexture, vascularity, and location of the thyroid gland. Technetium-99m-pertechnetate scans were evaluated for the presence and location of the thyroid gland. The ultrasound studies were compared with the ^99mTc-pertechnetate scans. We assessed the use of ultrasound as the primary imaging modality for the evaluation of CH.

RESULTS. We identified the cases of 124 patients (89 girls, 35 boys). Ultrasound studies were available for 121 patients, and ^99mTc-pertechnetate studies for 62 patients. Three patients were examined only by ^99mTc-pertechnetate scanning. The final imaging results were normal location with normal size or diffuse enlargement of the thyroid gland (n = 47), sublingual thyroid gland (n = 49), agenesis (n = 18), hypoplasia (n = 8), and hemiagenesis (n = 2). Compared with ^99mTc-pertechnetate scanning, ultrasound had high (100%) specificity and low (44%) sensitivity for detection of sublingual thyroid gland.

CONCLUSION. We suggest using ultrasound as the primary imaging modality for guiding the treatment of children with CH, potentially decreasing radiation exposure and cost.

 

Congenital hypothyroidism (CH) is defined as thyroid hormone deficiency present at birth. It can be subdivided into permanent and transient types. Permanent CH refers to persistent deficiency of thyroid hormone that requires lifelong treatment [1]. Transient CH refers to a temporary deficiency of thyroid hormone. The deficiency is present at birth, but recovery to normal thyroid hormone production usually occurs within the first few months or years of life.

Almost all neonates are screened for CH. A heelstick is performed to evaluate the level of thyroid-stimulating hormone (TSH). All infants with high TSH levels are considered to have CH until proven otherwise [1]. Most cases of CH are asymptomatic at birth, but if left untreated, the condition can lead to growth failure and profound mental retardation between 3 and 6 months of age [1–5]. The incidence of CH is 1:3000–1:4000 [1, 6].

In undeveloped countries, the most common cause of CH is iodine deficiency (transient CH), but in the developed world, 85% of cases of CH are caused by thyroid dysgenesis (aplasia, hypoplasia, or ectopia). Inborn errors of thyroid hormone biosynthesis (dyshormonogenesis) or defects in peripheral thyroid hormone transport, metabolism, or action account for 10–15% of cases and are also associated with genetic defects. Secondary, or central, CH may occur with isolated TSH deficiency, but more commonly it is associated with congenital hypopituitarism [1].

Determining the cause of CH guides management and genetic consultation because it has prognostic implications [1]. Although thyroid hormone replacement is the initial treatment in all cases, if the patient has a normal-appearing eutopic thyroid gland, a trial of discontinuing levothyroxine when the patient is approximately 3 years old is often undertaken to differentiate permanent from transient CH. If the thyroid gland adequately functions, no further replacement hormone is required. If no thyroid tissue is found or if dyshormonogenesis has occurred, the child needs thyroid supplementation for life.

Imaging studies to help determine the underlying cause of CH include thyroid radionuclide examinations and thyroid ultrasound. Thyroid radionuclide studies with ^99mTc-pertechnetate or ¹²³I are considered the standard for imaging in the evaluation of thyroid dysgenesis. Although ^99mTc-pertechnetate is preferred because of lower thyroid and total body radiation dose (≈ 0.04 mSv compared with 0.35 mSv) [7], both result in radiation exposure to the patient. In the case of eutopic location of the thyroid gland, an ¹²³I uptake followed by a ^99mTc-pertechnetate perchlorate discharge test is the definitive study for identifying an organification defect of the thyroid gland [8].

Sonography does not involve the risk of ionizing radiation and can be used to differentiate thyroid dysgenesis and other causes of CH in which the thyroid gland has normal morphologic features [9, 10]. Sonography, however, has lower sensitivity than ^99mTc-pertechnetate scintigraphy in the detection of sublingual thyroid. The use of color Doppler ultrasound (CDUS), however, has been found to increase the detection of sublingual ectopic thyroid [1, 2, 5, 11].

For several years at our facility, we have been using sonography as the primary screening imaging modality in the care of patients with CH and using ^99mTc-pertechnetate scintigraphy primarily for patients with thyroid dysgenesis. In this study, we summarize the experience with the use of ultrasound in CH that led us to recommend using an ultrasound-based imaging algorithm [12, 13].

Materials and Methods

Patients

A retrospective review was performed of the cases of all patients whose condition was diagnosed as CH at our institution between January 1, 2003, and December 31, 2010. Only patients whose thyroid ultrasound or ^99mTc-pertechnetate scans were available for review were included. Institutional review board approval was obtained with a waiver of informed consent for the study. All but three CH patients were initially imaged with thyroid ultrasound. The decision to order a ^99mTc-pertechnetate scan was then made by an endocrinologist on the basis of the ultrasound results. Typically ^99mTc-pertechnetate scanning was performed to evaluate or confirm ectopic sublingual thyroid when ultrasound showed thyroid dysgenesis.

TABLE 1:Reference Standard for Thyroid Size (cm) by Age

TABLE 2:Causes of Congenital Hypothyroidism in 124 Patients Between 2003 and 2010

Fig. 1:Photograph shows ideal patient position with hyperextended neck.

Imaging Technique

For thyroid sonography, all patients were examined in the supine position with the neck hyperextended by placement of a folded towel beneath the scapula (Fig. 1). A 7–15 MHz linear transducer with a small footprint was used (Acuson Sequoia 512, Siemens Healthcare, or HDI 5000 IU 22, Philips Healthcare). Gray-scale transverse and longitudinal images were obtained from the base of the tongue. CDUS was performed in some patients to better depict ectopic sublingual thyroid.

For ^99mTc-pertechnetate scintigraphy, the scan was performed with 1–2 mCi of ^99mTc-pertechnetate IV (dose calculated on basis of patient’s weight). Images were obtained in the anterior and lateral views 15 minutes after administration.

Imaging Evaluation and Data Analysis

All of the imaging studies were reviewed at our standard clinical PACS workstation (Synapse, Fujifilm). Both ultrasound and ^99mTc-pertechnetate scans were separately and independently reviewed by a pediatric radiologist (fellowship trained with 5 years of experience) and a nuclear medicine physician (30 years of experience).

Ultrasound studies were reviewed for the presence (eutopic, ectopic, or agenesis) of thyroid tissue, size (normal, hypoplastic, or hyperplastic) compared with the reference standard (Table 1) [14], echotexture (normal or increased echogenicity), and degree of thyroid vascularity (normal, increased, decreased). Technetium-99m-pertechnetate scans were evaluated for the presence (eutopic, ectopic or agenesis) of thyroid tissue and subjective degree (normal, increased, or decreased) of radiotracer uptake.

We used descriptive statistical analysis for each modality, divided into eutopic location, ectopic location, and agenesis of the thyroid gland. We also compared the sensitivity, specificity, and accuracy of the modalities using ^99mTc scintigraphic results (when available) as the reference standard. On ultrasound images we evaluated the presence, location, size, echotexture, and vascularity of thyroid gland, and on the ^99mTc-pertechnetate studies—the reference standard for evaluation of sublingual thyroid— we evaluated presence, location, size, and uptake.

Discussion

The treatment of CH patients is empiric and not guided by imaging findings. A neonate with a diagnosis of CH is immediately treated with thyroid hormone replacement [15]. Using a higher starting dose to more quickly normalize TSH levels to the target range within 2 weeks to normalized developmental IQ even in patients with severe CH is the main purpose of treatment. The initial thyroid hormone (levothyroxine) dose for eutopic thyroid gland is approximately 10 μg/kg/d, compared with 15 μg/kg/d for noneutopic thyroid gland [16].

Permanent CH can be assumed if ultrasound or radionuclide imaging shows the thyroid gland is absent or ectopic (together referred to as dysgenesis) or if at any time during the first year of life, the serum TSH concentration rises above 20 mU/L owing to undertreatment. The American Academy of Pediatrics and the European Society for Pediatric Endocrinology recommend that if permanent CH has not been established by 2–3 years of age, a 30-day trial without thyroid hormone be undertaken. If low serum T4 and elevated TSH concentrations are found, permanent CH is confirmed, and therapy is restarted [1]. If a patient has a eutopic thyroid gland, and the gland produces adequate thyroid hormone in the 30-day trial, a diagnosis of transient CH is established, and the patient needs no further thyroid hormone replacement.

Thyroid scintigraphy is considered the reference standard for the evaluation of CH. There are several reports, however, of limitations of scintigraphy in diagnosing eutopic thyroid gland. Perry et al. [3] and several other groups [5, 17, 18] reported that ultrasound shows thyroid tissue in 2–15% of patients who have none visualized at scintigraphy. These studies included patients with maternal thyrotropin receptor–blocking antibodies, exposure to maternal antithyroid medications, iodine deficiency, or iodine excess causing transient hypothyroidism [1, 5, 15, 17, 18]. These patients may have transient hypothyroidism and would likely not need thyroid hormone replacement for life. Therefore, in patients with a eutopic thyroid gland, no uptake at scintigraphy may be misleading.

In our 7-year cohort of patients with CH, we found a higher frequency of eutopic thyroid gland than reported in the literature. This finding may be related to a higher percentage (36%) of transient hypothyroidism in our screening program [8]. Regardless of the underlying cause, the initial treatment of CH is the same. However, patients with eutopic thyroid gland may need further investigation to differentiate between the permanent and transient forms of CH.

The reported incidence of primary hypothyroidism has increased in the United States over the last two decades. One of the possible causes is inclusion of more cases of transient hypothyroidism. It is important to have a precise diagnosis of eutopic thyroid gland because this can lead to change in treatment [15]. Therefore, some authors advocate the use of both scintigraphy and ultrasound for optimal functional and anatomic detail [5, 8, 19].

Several investigators who used both scintigraphy and ultrasound for the diagnosis of CH have recommended ultrasound as a first-line study to avoid radiation associated with scintigraphy [17, 20, 21]. We are the first, to our knowledge, to report experience using thyroid ultrasound as the primary imaging evaluation of CH with selective use of scintigraphy in children with thyroid dysgenesis.

The main limitation of ultrasound is decreased sensitivity in the evaluation of ectopic thyroid gland. The ultrasound diagnosis of ectopic thyroid gland depends on technique and the experience of the sonographer. Marked variation in sensitivity (0–80%) has been reported among medical centers [1–3, 5, 11, 18, 19]. The sensitivity of sonography in the detection of ectopic thyroid gland in our series was 44%. Using CDUS increases the sensitivity of diagnosis of ectopic thyroid gland [1, 2, 5, 11]. In our series, in most cases of missed ectopic thyroid gland, CDUS was not used. The reported specificity of ultrasound in the detection of ectopic thyroid gland is high [1–3, 5, 11, 18, 19, 21]. In our series, the specificity of sonography was 100%.

Our experience showed that when ultrasound depicts ectopic or eutopic thyroid gland, the scintigraphic results will not change the initial management. For precise diagnosis of agenesis versus sublingual thyroid gland in all patients with ectopic thyroid gland, scintigraphy can be used selectively when ultrasound does not depict any thyroid tissue. In our series, that would have obviated scintigraphy for 54% of the patients.

For management guidance, it is important to differentiate patients with eutopic thyroid gland from those with thyroid dysgenesis. Patients with thyroid dysgenesis are being treated for life with thyroid hormone replacement. The ectopic thyroid gland eventually involutes owing to suppression of TSH. Differentiation between thyroid agenesis and ectopic thyroid gland does not change management. Scintigraphy can therefore be used selectively only in cases of equivocal ultrasound findings, such as hypoplastic thyroid gland. In our series, we did not perform scintigraphy for most patients with eutopic thyroid gland and therefore do not have a correlation with thyroid size or parenchymal echotexture. With this management, we would remove the need for scintigraphy for 90% of patients. This approach will save both radiation and cost with no change in management.

Imaging of patients with CH has a role in the evaluation of the cause, in prognosis, and in guiding management. Ultrasound of the thyroid can be used to differentiate patients with thyroid dysgenesis from patients with eutopic thyroid. Thyroid dysgenesis is typically a sporadic disorder and carries no recurrence risk of CH with future pregnancies. Patients with eutopic thyroid gland are a heterogeneous group; some have a risk of recurrence in future pregnancies. Genetic consultation can be considered [1].

Our study had several limitations. First, our study was performed as a retrospective review of imaging findings, and there was inconsistent use of CDUS, possibly decreasing sensitivity in the detection of ectopic sublingual thyroid gland. Second, the ultrasound and ^99mTc studies were reviewed by a single radiologist, possibly biasing interpretation of the studies. However, compared with original reports, in only two studies (3%) did the retrospective evaluations vary. Because the studies were reviewed by a single radiologist, we could not assess interobserver variability. Third, we imaged only patients who were evaluated prenatally at our institute. Fourth, the study did not include follow-up on euthyroid patients. However, the incidence of transient hypothyroidism in our institution (36%) had been published [8].

Conclusion

Ultrasound can be used as the primary imaging modality for guiding treatment of children with CH, potentially decreasing radiation exposure and cost. Scintigraphy can be reserved for the few patients with equivocal ultrasound findings, such as hypoplastic thyroid gland.

AJR:199, September 2012

INVASIVE DUCTAL CARCINOMA of the BREAST

Abstract

OBJECTIVE. The purpose of this study was to compare the efficacy of the sonographic features in the BI-RADS lexicon for predicting malignancy grade of invasive ductal breast carcinoma in women assigned a BI-RADS category of 4 or 5.

MATERIALS AND METHODS. Two radiologists retrospectively evaluated 299 consecutive cases of grades 1–3 invasive ductal breast carcinoma presenting as a mass in consensus by using the BI-RADS sonographic lexicon. Histologic grade was established on surgical specimens. Effect sizes were calculated via the Goodman and Kruskal tau, an asymmetric measure of strength of nominal association, and results were interpreted in terms of proportional reduction in error.

RESULTS. Thirty-eight lesions (13%) were grade 1, 153 (51%) were grade 2, and 108 (36%) were grade 3, with the majority of all masses showing an irregular shape (84%) and hypoechoic echotexture (82%). Of the sonographic features examined, malignancy grade was best predicted by posterior acoustics (τ = 0.13, p < 0.001), lesion boundary (τ = 0.05, p < 0.001), and margin (τ = 0.04, p = 0.001). Among grade 3 lesions, there were significantly more lesions with posterior enhancement (53 vs 27.6; adjusted standardized residuals (z_res) = 7; p < 0.001), abrupt interfaces (68 vs 51.2; z_res = 4; p < 0.001), and microlobulated margins (12 vs 5.8; z_res = 3; p = 0.001) than would be expected.

 

CONCLUSION. Malignancy grade was slightly to moderately predicted by margin, lesion boundary, and acoustic sonographic features. In particular, grade 3 invasive ductal breast carcinomas were more likely than expected to display microlobulated margins, abrupt interfaces, and posterior enhancement

DOPPLER ĐỘNG MẠCH NÃO GIỮA ĐỂ CHẨN ĐOÁN THIẾU MÁU SƠ SINH

© 2012 by the American Institute of Ultrasound in Medicine

More than a decade ago, Mari et al1,2 achieved a major breakthrough in the treatment of Rh-sensitized fetuses with their pioneering work that showed a correlation between the Doppler middle cerebral artery peak systolic velocity (PSV) and fetal hemoglobin levels. This technique has virtually eliminated the need for invasive procedures such as amniocentesis and cordocentesis that have been used for diagnosis of fetal anemia with their inherent complications. Since then, the middle cerebral artery PSV has been the standard of care for treatment of anemic fetuses. Doppler studies have also been used in neonates with different cerebral conditions (eg, intraventricular hemorrhage, brain lesions, and hydrocephalus).3–6 However, this approach has not been attempted in neonates suspected to have blood volume disorders such as anemia and polycythemia. If a correlation between neonatal hemoglobin levels and the middle cerebral artery PSV is found, it may be similarly applied for rapid, noninvasive bedside diagnosis of acute life-threatening conditions in neonates until the standard blood tests can be performed.

The aims of this study were therefore to determine whether a correlation exists between the neonatal middle cerebral artery PSV and hemoglobin levels and to assess the possibility of implementing this indicator for rapid, noninvasive diagnosis of blood volume disorders in neonates.

Materials and Methods

Study Population

This prospective study included 151 healthy neonates, weight appropriate for gestational age, born at our medical center during a 6-month period. All neonates were delivered at 37 weeks’ gestation or later with Apgar scores of 7 or higher at 5 minutes. We excluded all neonates with malformations, intrauterine growth restriction, perinatal asphyxia, and infections. The local Research Ethics Institutional Review Committee approved the study, and informed consent was obtained from the mother of each neonate enrolled in the study. Medical examinations by a senior pediatrician confirmed that all neonates enrolled in the study were healthy without dysmorphic features. The neonates were born by spontaneous vaginal delivery or cesarean delivery. All neonates were prospectively studied on the second day of life (between 24 and 36 hours after delivery). Anemia was defined as a hemoglobin level of 13.5 g/dL or less or a hematocrit value 45% or less, and polycythemia was defined as a hemoglobin level greater than 22 g/dL or a hematocrit value greater than 65%.7

Doppler Studies

Doppler examinations of the middle cerebral artery were performed with a Voluson 730 ultrasound system (GE Healthcare, Solingen, Germany) and a convex transducer (4–8 MHz) in a quiet room. The neonates were sleeping in a crib without gross body or limb movements and were breathing quietly. The examinations were performed by using an axial plane on the temporal bone anterior to the external auditory canal and superior to the zygomatic process, identifying the middle cerebral artery. Measurements were obtained just distal to the middle cerebral artery origin from the internal carotid artery. The angle of insonation was close to 0°, thus obviating the need for angle correction (Figure 1). The sample gate was 3 to 4 mm. The total examination time was 1 to 3 minutes. Five Doppler waves were recorded, and the highest PSV waveform was used for analysis.

Statistics

An analysis of variance was performed to evaluate the different variables in the 3 groups studied (normal, anemic, and polycythemic neonates). Multiple comparison analyses were performed as well to determine whether the variable means were statistically different from each other. A regression analysis was conducted to test correlations between hemoglobin levels and middle cerebral artery PSVs in the whole groups. P < .05 was considered significant.

Results

The study population included 122 normocythemic, 24 anemic, and 5 polycythemic neonates. The mean gestational age ± SD of the neonates at delivery was 39 ± 1.5 weeks, with a median Apgar score of 10 at 5 minutes and a mean birth weight of 3290 ± 446 g.

Table 1 presents the hemoglobin, hematocrit, and PSV values of the 3 groups. There were significant differences in the hemoglobin, hematocrit, and PSV values between the normocythemic neonates and the anemic and polycythemic neonates (P < .001). Of the 24 anemic neonates, 20 (83%) had a middle cerebral artery PSV that was higher than the 95% confidence interval (CI) for normocythemic neonates, and all 5 polycythemic neonates had a PSV that was lower than the 95% CI for normocythemic neonates.

 

 

 

In Figure 2, the means and 95% CIs of the middle cerebral artery PSV values in the 3 groups (anemic, normocythemic, and polycythemic) are shown. Although there are overlapping values, the means of the 3 groups are significantly different and can be easily distinguished from each other (P < .01). Figure 3 depicts the middle cerebral artery PSV according to different hemoglobin levels (with the means and 95 percent CIs). A clear decrease in the PSV is evident with increasing hemoglobin levels (P < .01).



 

 

In Figure 4, the middle cerebral artery PSV of the 3 groups combined is depicted with a third-order polynomial fit regression line. Although there are overlapping values, the trend is clear (especially at the extremes of the hemoglobin levels) that the lower the hemoglobin concentration, the higher the PSV and vice versa. A significant correlation between the PSV and hemoglobin levels was found (P < .01). It is interesting to note that a plateau exists at hemoglobin levels considered to be within the normal range (±2 SDs) for neonates (at ≈13–22 g/dL), but below or above these limits, there are acute changes in the PSV.



 

In Figure 5, we show a vector plot of several anemic neonates who underwent partial exchange transfusion. The hemoglobin level and middle cerebral artery PSV were obtained at the bedside before the blood transfusion and 1 hour after the transfusion. The plot shows the trend of changes in the PSV, and the lines span from the starting to ending hemoglobin levels. Once more, it is clear that an increasing hemoglobin level caused an immediate decrease in the PSV. These fetuses with initial hemoglobin levels of 7.8 to 11.9 g/dL had PSVs of 51 to 144 cm/s, which rapidly decreased to approximately 32 to 80 cm/s when the hemoglobin levels increased to the normal range (>13 g/dL).



Discussion

This study shows that there is a significant correlation between hemoglobin levels and the middle cerebral artery PSV in neonates. Although overlapping measurements in the normal range of hemoglobin levels exist, the more severe degrees of anemia and polycythemia can be readily diagnosed by examining the middle cerebral artery PSV. Similarly to the well-established technique used in fetuses, this procedure can also be suitable in neonates for prompt diagnosis of life-threatening blood volume disorders. Obviously, we do not imply that this method can replace the traditional direct blood examination. However, it may be used as an ancillary, rapid means of noninvasively estimating the degree of anemia or polycythemia in neonates suspected to have blood volume disorders, thus allowing prompt action. There are several neonatal conditions in which middle cerebral artery PSV can be rapidly used for diagnosis of anemia and polycythemia. These include anticipated deliveries of twins affected by twin-twin transfusion syndrome, neonates affected by Rh and Kell isoimmunization, thalassemia, parvovirus B19 infection, and hydrops. In addition, acute intrapartum events such as intracranial hemorrhage, a large cephalhematoma, and other hemorrhages associated with traumatic instrumental delivery with loss of a substantial amount of blood or a sudden decrease in blood volume can be immediately recognized at the bedside when clinical suspicion dictates. Even critically ill neonates for whom venous access is difficult (eg, hydropic neonates) can have a prompt diagnosis until blood tests can be safely performed. The appealing aspect of this technique is that it can be easily studied and mastered even by novice users in a very short period.

The underlying pathophysiologic mechanism of increased cardiac output and decreased blood viscosity in anemic fetuses is valid also for neonates, as shown in this study. Anemia causes an increase in the cardiac stroke volume, heart rate, and peripheral resistance and decreased blood viscosity, leading to an increase in cerebral blood flow to maintain adequate oxygen transport to the brain.8,9 Neonates, similarly to fetuses, obey the same physical laws of flow velocities in blood vessels.

Polycythemia, on the other hand, occurs in 2% to 5% of term neonates,10 usually as a compensatory mechanism in intrauterine hypoxia or uncontrolled diabetic pregnancies with macrosomic neonates or as a result of delayed cord clamping.11 This condition may lead to hyperviscosity of the blood with altered rheologic properties and flow disturbances, which can result in impaired perfusion to multiple organs. This situation can cause neurologic, cardiorespiratory, gastrointestinal, and renal abnormalities.12–15 Although these symptoms are usually transient, prompt diagnosis and treatment may be life saving with reversal of the potential damage.16,17

We found that for the established normal range of hemoglobin levels, the middle cerebral artery PSV has a plateau, whereas in anemia and polycythemia, the PSV changes rapidly (increasing and decreasing, respectively). The correlation between hemoglobin levels and the PSV becomes more pronounced as the severity of anemia or polycythemia increases (Figure 2). This factor may be due to the rheologic properties of the blood in neonates. Flow remains almost constant for a wide range of hemoglobin levels but rapidly changes as the hemoglobin levels decrease or increase beyond certain limits. It is interesting to note that the middle cerebral artery PSVs of the term neonates in this study (Table 1) were very similar to those reported by Mari et al2 in term fetuses, and anemic fetuses had PSVs similar to those of anemic neonates.

As to the question of whether this technique can be implemented in clinical practice, we have shown several neonates who underwent partial exchange transfusion because of anemia and were studied with the Doppler middle cerebral artery PSV before and after the transfusion (Figure 4). It is evident that normalizing the hemoglobin level rapidly corrects the PSV. We think that in polycythemic neonates, the contrary occurs as well.

This study had some limitations. We studied only term neonates 24 to 36 hours after delivery, examining our hypothesis that the Doppler middle cerebral artery PSV can be helpful in managing neonatal emergencies occurring in the first days after delivery (eg, intracerebral bleeding due to traumatic delivery). Because it has been reported that the PSV progressively changes during the first month of life,18 the flow velocities may be different later, and caution should be used in interpreting hemoglobin levels as a function of the middle cerebral artery PSV in older neonates.

Although it is appealing to also use this technique in premature neonates to diagnose acute anemia caused by massive hemorrhage, a caveat should be addressed in this group as well. The situation may be different in premature neonates in whom the proportion of hemoglobin F is different, and there may be different rheologic properties of the blood due to a different elasticity or size of the red blood cells. This issue should be further studied in the future. An additional factor that was not controlled for but may potentially alter the middle cerebral artery PSV is the presence or absence of a patent ductus arteriosus. However, the impact of the ductus on blood flow to the brain has been reported to be minimal19; therefore, we think that this factor may have only a marginal effect on middle cerebral artery PSV measurements in anemic and polycythemic neonates.

In conclusion, Doppler measurement of the middle cerebral artery PSV appears to be helpful for estimating the hemoglobin concentration in neonates and can be used as a screening tool for diagnosing neonatal anemia and polycythemia. This technique may allow a rapid, noninvasive determination of the neonatal hemoglobin level, dictating the urgency of treatment.