Objective. To describe the ultrasound features of gas in the portal venous system and intramural gas in hollow organs in various pathologies, including both bowel wall necrosis and various transient non-necrotic conditions, using clinical case examples.
Materials and methods. Between June 1 and November 9, 2024, at the S.S. Yudin City Clinical Hospital (Moscow Department of Health), ultrasound signs of gas in the portal venous system were detected in 16 patients. All these patients exhibited a severe overall condition, required treatment in the intensive care unit, and had unstable hemodynamics necessitating vasopressor therapy. The article presents the most illustrative clinical cases of portal venous gas from this cohort of 16 patients.
Results. Case analysis demonstrated that the presence of gas in the portal venous system is not always indicative of bowel wall necrosis and may result from transient conditions.
Conclusions. Ultrasound allows for the detection of gas within the portal venous system and within the walls of hollow organs. The presence of portal venous gas on ultrasound should not be interpreted as a sign of a single, specific disease, as it may reflect a range of pathological or transient conditions. Decisions regarding further diagnostic and therapeutic strategies upon detection of intramural or portal venous gas should be based on clinical and laboratory data.

Kidney transplantation is recognized as the optimal modality of renal replacement therapy. In most cases the diagnosis of the causes of kidney allograft dysfunction and subsequent choice of treatment strategy are determined by the results of nephrobiopsy. The search for alternative noninvasive diagnostic modalities, including ultrasound, that could reveal the specific features of the most common causes of renal graft dysfunction remains relevant. Contrast-enhanced ultrasound (CEUS)is considered a promising modality for the diagnosis of renal graft dysfunction in general and of acute rejection in particular.

The article presents the analysis of the results of multiparametric ultrasound in a patient with acute antibody-mediated rejection after voluntary complete withdrawal of immunosuppressive therapy. The subcapsular areas of hypoperfusion were found along with a decrease of allograft perfusion in general. The patterns of “slow wash-in – fast wash-out” of contrast medium in the medulla and “fast wash-out” in the cortex were also detected. The comparison of CEUS and histopathological data from the removed allograft identified the foci of cortical necrosis as the substrate of abnormal perfusion areas. Now it seems premature to evaluate the diagnostic capability of CEUS in complex ultrasound of renal allograft. Further research is necessary to determine the role of CEUS in the complex assessment of kidney transplant pathology.

The article presents a case of ultrasound diagnosis of torsion of an ectopic spleen in a 14-year-old girl who underwent surgery during the neonatal period for a left-sided congenital diaphragmatic hernia. The ultrasound findings of this extremely rare condition—manifesting clinically as an acute abdomen and requiring emergency surgical intervention—are described in detail. Attention is drawn to the key ultrasound signs that raised suspicion for this pathology and indicated the need for surgical treatment. The article emphasizes the importance of maintaining a high index of clinical suspicion for this uncommon developmental anomaly and highlights the crucial role of ultrasound examination in its diagnosis. A brief literature review is provided, addressing the developmental nature of the condition and the challenges of its preoperative diagnosis.

Ultrasound is the primary diagnostic modality for evaluating pelvic organ pathology in young girls, with ovarian cysts being the most commonly encountered condition. Accurate normative reference values for the size of reproductive organs, along with knowledge of their physiological features during the first months of life, are essential for detecting abnormalities and determining appropriate management strategies. Data obtained over the past decade has demonstrated that ovarian follicle size in girls during the first year of life is larger than previously assumed. Moreover, the dimensions of the uterus and ovaries change significantly throughout this period, most likely reflecting changes  in gonadotropin levels during *mini-puberty*.  The review summarizes ultrasound-based data on the structure and size of pelvic organs in healthy female infants during the first months of life, describes the ovarian cysts features and different management approaches at this age, and discusses the main causes and possible consequences of hypothalamic-pituitary-gonadal axis activation after birth (*mini-puberty*).

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous orphan lymphoproliferative disorder characterized by an aggressive course. Due to its unusual nature, primary ovarian lymphoma lacks specific clinical features and may be mistaken for other types of ovarian malignancies. It poses a dual diagnostic and therapeutic challenge. Imaging plays a central role in diagnosing ovarian lymphoma, and radiologists should be familiar with the sonographic, computed tomography (CT), and magnetic resonance imaging (MRI) features of this condition in order to guide diagnostic workup and avoid unnecessary adnexectomy. Particular attention should be paid to thorough evaluation of the adnexa during preconception screening and during routine obstetric ultrasound, which are typically performed at least three times throughout pregnancy: in early gestation and at 11–14 weeks and 19–21 weeks of pregnancy.

Aortic coarctation is one of the etiological factors of secondary arterial hypertension. Owing to prenatal diagnostics and modern neonatal screening protocols, in most cases aortic coarctation is identified during the neonatal period. However, according to the literature, in older children and adults aortic coarctation is missed in approximately 85% of cases, even in the presence of such clinical manifestations as heart murmur or arterial hypertension. The article presents a clinical case of an adolescent with newly diagnosed type III aortic coarctation (complete form), complicated by secondary arterial hypertension. Analysis of the literature data and diagnostic errors observed in the patient’s work-up allowed to highlight the following diagnostic approaches that significantly facilitate timely and accurate diagnosis.
1.    Bilateral blood pressure measurement at the initial examination of adolescents and adult patients with arterial hypertension, particularly in cases of refractory hypertension and the presence of a cardiac murmur.
2.    In situations of technical difficulties in blood pressure measurement by conventional methods (auscultatory, oscillometric, etc.) in the lower extremity arteries, it is recommended to assess systolic pressure by Doppler ultrasound following the method of ankle–brachial index measuring. A simplified approach can be applied by preliminarily assessing the shape of the flow spectrogram.
3.    Mandatory screening ultrasound evaluation of the abdominal aorta should be included in the basic protocol of transthoracic echocardiography.