Dengue fever is a major mosquito-borne viral infection and an important public health concern, particularly in tropical and subtropical regions. It is caused by the dengue virus (DENV), which belongs to the genus Flavivirus and is transmitted primarily through infected Aedes aegypti mosquitoes[1]. The global burden of dengue has increased considerably over recent decades, with substantial morbidity and mortality in endemic countries. Children are particularly vulnerable to dengue-associated complications, as the infection may progress from a mild febrile illness to severe disease characterized by plasma leakage, hemorrhagic manifestations, circulatory shock, and organ dysfunction. Early recognition of disease severity and timely intervention are therefore essential for improving clinical outcomes [2].Dengue infection exhibits a broad spectrum of clinical manifestations, ranging from asymptomatic infection to life-threatening complications. According to the revised World Health Organization (WHO) classification, dengue is categorized into dengue without warning signs, dengue with warning signs, and severe dengue. Common manifestations in children include fever, headache, vomiting, abdominal pain, myalgia, and skin rash. Warning signs such as persistent vomiting, abdominal tenderness, mucosal bleeding, lethargy, hepatomegaly, and clinical fluid accumulation may indicate progression toward severe disease. Increased capillary permeability and subsequent plasma leakage are important pathophysiological features of severe dengue, resulting in ascites, pleural effusion, hemoconcentration, and circulatory compromise [1,3,4].Ultrasonography is a noninvasive, inexpensive, and readily available imaging modality that plays an important role in evaluating dengue-associated complications. Its radiation-free nature and suitability for repeated examinations make it particularly useful in pediatric patients. Common ultrasonographic abnormalities include gallbladder wall thickening, ascites, pleural effusion, hepatomegaly, splenomegaly, and pericholecystic fluid accumulation. These findings are primarily associated with increased vascular permeability, tissue edema, and plasma leakage. Among these abnormalities, gallbladder wall thickening has been frequently reported as a potential sonographic indicator of disease severity [5–8].Previous studies have demonstrated associations between ultrasonographic abnormalities and dengue severity. Setiawan et al. [5] reported that pleural effusion, ascites, and gallbladder wall thickening were associated with increasing severity of dengue hemorrhagic fever. Similarly, Colbert et al. [9] demonstrated the usefulness of gallbladder wall thickening as a prognostic indicator of severe dengue in pediatric patients. Pothapregada et al. [10] further reported that selected ultrasonographic findings were significantly associated with severe dengue infection among children. Oliveira et al. [11] highlighted the significance of reticular gallbladder wall thickening as a sonographic manifestation of plasma leakage in severe dengue. These findings suggest that ultrasonography may complement clinical examination and laboratory investigations in identifying children at increased risk of complications.Despite these observations, the relationship between individual ultrasonographic abnormalities and clinical severity requires further evaluation in pediatric populations. Variations in clinical presentation, timing of examination, and severity classification may influence the frequency and significance of sonographic findings. Moreover, early detection of fluid accumulation through ultrasonography may provide additional information regarding disease progression and support clinical monitoring [8,12]. Therefore, the present study was designed to evaluate the ultrasonographic findings in children with dengue fever and determine their correlation with clinical severity, thereby assessing the potential role of ultrasonography as an adjunctive tool in pediatric dengue management.

This hospital-based prospective observational study was at a tertiary care hospital.A total of 120 children with confirmed dengue fever were included in the study. Inclusion Criteria 1. Children aged 1–18 years with confirmed dengue fever. 2. Patients testing positive for dengue NS1 antigen, IgM antibody, or RT-PCR. 3. Children whose parents or guardians provided written informed consent. Exclusion Criteria 1. Children with pre-existing chronic hepatic, renal, or cardiac diseases. 2. Patients with known gallbladder disorders or conditions causing ascites or pleural effusion. 3. Children with concurrent infections affecting ultrasonographic findings. 4. Patients whose parents or guardians declined consent. Grouping of Patients The 120 children were classified into three groups according to the WHO 2009 dengue severity classification: • Group I: Dengue without warning signs. • Group II: Dengue with warning signs. • Group III: Severe dengue. Patients were categorized according to the highest clinical severity observed during their illness. Data Collection and Clinical Assessment Demographic details, clinical history, duration of fever, presenting symptoms, and physical examination findings were recorded using a structured proforma. Clinical assessment included evaluation of bleeding manifestations, hepatomegaly, fluid accumulation, and circulatory status. Laboratory investigations, including complete blood count, platelet count, hematocrit, and liver function tests, were recorded. Ultrasonographic Examination All patients underwent ultrasonographic examination of the abdomen and assessment of the pleural spaces using a real-time ultrasound machine. The examination was performed by a qualified radiologist. Ultrasonographic findings, including gallbladder wall thickening (greater than 3 mm), ascites, pleural effusion, hepatomegaly, splenomegaly, and pericholecystic fluid collection, were recorded. Organ enlargement was assessed using age-appropriate reference values. The findings were compared across the three clinical severity groups. Outcome Measures The primary outcome was the correlation between ultrasonographic abnormalities and clinical severity of dengue fever. Secondary outcomes included the frequency of individual sonographic findings and their association with platelet count and hematocrit. Statistical Analysis Data were entered into Microsoft Excel and analyzed using SPSS. 27 software. Categorical variables were expressed as frequencies and percentages, while continuous variables were presented as mean ± standard deviation or median (interquartile range), as appropriate. The Chi-square test or Fisher's exact test was used for categorical comparisons, while ANOVA or the Kruskal–Wallis test was applied for continuous variables. Spearman's correlation coefficient was used where appropriate. A p-value <0.05 was considered statistically significant.

A total of 120 pediatric patients diagnosed with dengue fever were included in the study. The majority belonged to the 6–10-year age group (35.00%), followed by 11–15 years (31.67%). Males constituted 56.67% of the study population. Based on clinical severity, 40.00% of patients had dengue without warning signs (Group I), 41.67% had dengue with warning signs (Group II), and 18.33% had severe dengue (Group III) (Table 1).Fever was present in all patients (100.00%), followed by vomiting (71.67%), abdominal pain (65.00%), headache (60.00%), and myalgia (54.17%). Other manifestations included skin rash (31.67%), clinical hepatomegaly (26.67%), bleeding manifestations (20.00%), and lethargy/restlessness (18.33%) (Table 2).Ultrasonographic examination revealed gallbladder wall thickening as the most common abnormality (60.00%), followed by ascites (48.33%), hepatomegaly (43.33%), pleural effusion (38.33%), pericholecystic fluid (25.00%), and splenomegaly (23.33%). No ultrasonographic abnormality was detected in 20.00% of patients (Table 3 and Figure 1).The prevalence of ultrasonographic abnormalities increased progressively with clinical severity. Gallbladder wall thickening increased from 25.00% in Group I to 95.45% in Group III, while ascites increased from 10.42% to 90.91% and pleural effusion from 6.25% to 86.36%. Similar increasing trends were observed for hepatomegaly, splenomegaly, and pericholecystic fluid (Table 4).Laboratory findings showed a progressive decline in mean platelet count from 118.5 ± 32.6 × 10³/µL in Group I to 42.8 ± 19.5 × 10³/µL in Group III. Conversely, mean hematocrit increased from 36.2 ± 3.8% to 45.8 ± 5.1%. Liver enzymes also increased with severity, with AST rising from 62.4 ± 24.5 to 185.2 ± 68.4 U/L and ALT from 48.6 ± 20.3 to 142.8 ± 55.2 U/L (Table 5 and Figure 2).Spearman's correlation analysis demonstrated significant positive correlations between ultrasonographic findings and clinical severity. The strongest correlation was observed for ascites (ρ = 0.639, p < 0.001), followed by pleural effusion (ρ = 0.606, p < 0.001), gallbladder wall thickening (ρ = 0.585, p < 0.001), and pericholecystic fluid (ρ = 0.521, p < 0.001). Hepatomegaly (ρ = 0.329, p < 0.001) and splenomegaly (ρ = 0.294, p = 0.001) also showed significant positive correlations (Table 6 and Figure 3). Table 1: Distribution of Study Participants According to Demographic Characteristics and Clinical Severity (N = 120) Characteristics Number of patients Percentage (%) Age group (years) 1–5 24 20.00 6–10 42 35.00 11–15 38 31.67 16–18 16 13.33 Gender Male 68 56.67 Female 52 43.33 Clinical severity Group I – Dengue without warning signs 48 40.00 Group II – Dengue with warning signs 50 41.67 Group III – Severe dengue 22 18.33 Table 2: Distribution of Patients According to Clinical Manifestations (N = 120) Clinical manifestations Number of patients Percentage (%) Fever 120 100.00 Vomiting 86 71.67 Abdominal pain 78 65.00 Headache 72 60.00 Myalgia 65 54.17 Skin rash 38 31.67 Clinical hepatomegaly 32 26.67 Bleeding manifestations 24 20.00 Lethargy/restlessness 22 18.33 Table 3: Distribution of Ultrasonographic Findings Among Study Participants (N = 120) Ultrasonographic findings Number of patients Percentage (%) Gallbladder wall thickening 72 60.00 Ascites 58 48.33 Pleural effusion 46 38.33 Hepatomegaly 52 43.33 Splenomegaly 28 23.33 Pericholecystic fluid 30 25.00 No ultrasonographic abnormality 24 20.00 Table 4: Association of Ultrasonographic Findings with Clinical Severity of Dengue Fever (N = 120) Ultrasonographic findings Group I (n=48) Group II (n=50) Group III (n=22) Gallbladder wall thickening 12 (25.00%) 39 (78.00%) 21 (95.45%) Ascites 5 (10.42%) 33 (66.00%) 20 (90.91%) Pleural effusion 3 (6.25%) 24 (48.00%) 19 (86.36%) Hepatomegaly 12 (25.00%) 25 (50.00%) 15 (68.18%) Splenomegaly 5 (10.42%) 13 (26.00%) 10 (45.45%) Pericholecystic fluid 2 (4.17%) 12 (24.00%) 16 (72.73%) Table 5: Comparison of Laboratory Parameters According to Clinical Severity (N = 120) Laboratory parameters Group I (n=48) Group II (n=50) Group III (n=22) Platelet count (×10³/µL) 118.5 ± 32.6 76.4 ± 28.3 42.8 ± 19.5 Hematocrit (%) 36.2 ± 3.8 40.5 ± 4.2 45.8 ± 5.1 Hemoglobin (g/dL) 12.1 ± 1.3 12.8 ± 1.5 13.5 ± 1.7 Total leukocyte count (×10³/µL) 4.8 ± 1.6 3.9 ± 1.4 3.4 ± 1.2 AST (U/L) 62.4 ± 24.5 108.6 ± 42.8 185.2 ± 68.4 ALT (U/L) 48.6 ± 20.3 82.5 ± 35.6 142.8 ± 55.2 Table 6: Correlation Between Ultrasonographic Findings and Clinical Severity of Dengue Fever (N = 120) Ultrasonographic parameters Spearman's correlation coefficient (ρ) p-value Gallbladder wall thickening 0.585 <0.001 Ascites 0.639 <0.001 Pleural effusion 0.606 <0.001 Hepatomegaly 0.329 <0.001 Splenomegaly 0.294 0.001 Pericholecystic fluid 0.521 <0.001

In the present study, the majority of children belonged to the 6–10-year age group (35.00%), followed by 11–15 years (31.67%). Males constituted 56.67% and females 43.33% of the study population. Aggarwal et al. [13] studied 134 children with dengue hemorrhagic fever and dengue shock syndrome during an epidemic in Delhi, highlighting the considerable burden of severe dengue among children. Similarly, Shah et al. [14] investigated a dengue outbreak in Mumbai and evaluated predictors of dengue shock syndrome in pediatric patients.Fever was present in all patients (100%), followed by vomiting (71.67%), abdominal pain (65.00%), headache (60.00%), and myalgia (54.17%). Bleeding manifestations were observed in 20.00% of children. Kalayanarooj et al. [15], in a study involving 172 evaluable febrile children, identified 60 dengue cases (35%), including 32 with dengue fever and 28 with dengue hemorrhagic fever. Their findings emphasized the importance of early clinical and laboratory indicators in differentiating dengue from other febrile illnesses.In the present study, 40.00% of children had dengue without warning signs, 41.67% had dengue with warning signs, and 18.33% had severe dengue. Aggarwal et al. [13] documented severe pediatric dengue during the Delhi epidemic, while Shah et al. [14] highlighted the importance of identifying predictors of dengue shock syndrome. These observations support early severity assessment, although direct comparison of severity proportions is limited by differences in classification systems.Gallbladder wall thickening was the most frequent abnormality (60.00%), followed by ascites (48.33%), hepatomegaly (43.33%), and pleural effusion (38.33%). Quiroz-Moreno et al. [16], in a study of 132 patients, reported gallbladder wall thickening in 86%, pleural effusion in 66%, and ascites in 60%. These frequencies were higher than those in our study, possibly reflecting differences in disease severity and study populations.Gallbladder wall thickening increased from 25.00% in Group I to 78.00% in Group II and 95.45% in Group III. Similarly, ascites increased from 10.42% to 90.91%, while pleural effusion increased from 6.25% to 86.36% between Groups I and III. Quiroz-Moreno et al. [16] reported an association between gallbladder wall thickening greater than 5 mm and free abdominal fluid (φ = 0.2, p < 0.05), supporting the relationship between sonographic abnormalities and plasma leakage.Mean platelet count decreased from 118.5 ± 32.6 ×10³/µL in Group I to 42.8 ± 19.5 ×10³/µL in Group III, whereas hematocrit increased from 36.2 ± 3.8% to 45.8 ± 5.1%. Kalayanarooj et al. [15] reported higher aminotransferase levels among children with dengue hemorrhagic fever than among those with uncomplicated dengue. Aggarwal et al. [13] observed hematocrit greater than 40% in only 18% of children, suggesting that hematocrit alone may not adequately reflect clinical severity.In the correlation analysis, ascites showed the strongest positive correlation with severity (ρ = 0.639), followed by pleural effusion (ρ = 0.606), gallbladder wall thickening (ρ = 0.585), and pericholecystic fluid (ρ = 0.521). Quiroz-Moreno et al. [16] also reported associations between gallbladder wall abnormalities and abdominal fluid accumulation, although their analysis did not directly assess correlation with the WHO 2009 severity categories.Pleural effusion was observed in 38.33% of patients and increased to 86.36% among children with severe dengue. Lum et al. [17] reported three pediatric cases of dengue-associated acute respiratory distress syndrome, of whom two died. Their findings highlighted the potential severity of respiratory complications in dengue infection and the importance of recognizing plasma leakage.

The present study suggests that ultrasonographic findings, particularly gallbladder wall thickening, ascites, and pleural effusion, increase with the clinical severity of dengue fever in children. These abnormalities demonstrated positive correlations with disease severity, indicating their potential usefulness in identifying children requiring closer monitoring. Ultrasonography may serve as a valuable adjunct to clinical and laboratory assessment for evaluating pediatric dengue severity. LIMITATIONS The single-center study design and relatively small sample size (N = 120) may limit the generalizability of the findings. Additionally, the absence of serial ultrasonographic examinations and long-term follow-up may restrict assessment of the progression and resolution of sonographic abnormalities.

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