Sepsis remains a major cause of preventable morbidity, prolonged intensive care utilization, and death across diverse healthcare settings. The Sepsis-3 consensus defines sepsis as life-threatening organ dysfunction caused by a dysregulated host response to infection, emphasizing organ dysfunction rather than infection alone [1]. Subsequent validation studies demonstrated that changes in organ dysfunction scores provide clinically meaningful prognostic information among patients with suspected infection [2]. Septic shock represents a more severe subset in which circulatory and cellular-metabolic abnormalities substantially increase mortality risk [3]. Contemporary management therefore relies on early recognition, rapid antimicrobial therapy, hemodynamic stabilization, source control, and repeated assessment of organ function [4]. The Sequential Organ Failure Assessment (SOFA) score remains widely used to quantify dysfunction across respiratory, coagulation, hepatic, cardiovascular, neurologic, and renal systems [5]. Despite these advances, inexpensive bedside and laboratory indicators that identify patients at greater risk of deterioration remain valuable, particularly where access to specialized biomarkers is limited. Peripheral blood smear examination is an established laboratory method that can reveal dynamic hematological responses to systemic inflammation. In sepsis, accelerated granulopoiesis and intense cytokine stimulation can produce neutrophilic leukocytosis, toxic granulation, Döhle bodies, and cytoplasmic vacuolization. An adult observational study demonstrated that toxic granules, cytoplasmic vacuoles, and Döhle bodies were substantially more frequent in patients with sepsis than in those with noninfectious systemic inflammatory response syndrome [6]. Sepsis also alters erythrocyte structure, membrane properties, deformability, oxidative balance, and microcirculatory behavior, providing a biological basis for abnormalities such as anisocytosis, poikilocytosis, polychromasia, and other red-cell changes [7]. Circulating nucleated red blood cells (NRBCs), normally absent from adult peripheral blood, have been associated with severe physiological stress and increased mortality in critically ill populations [8], including patients with surgical sepsis [9]. Platelet abnormalities are equally relevant. Thrombocytopenia in sepsis reflects consumption, endothelial activation, immune-mediated destruction, marrow suppression, and sepsis-associated coagulopathy. Previous studies have linked thrombocytopenia and failure of platelet recovery with adverse prognosis [10,11]. Sepsis-associated disseminated intravascular coagulation represents the severe end of dysregulated coagulation and can be accompanied by thrombocytopenia and red-cell fragmentation, providing a mechanistic context for schistocyte formation [12]. In parallel, measures of erythrocyte size heterogeneity such as red cell distribution width have shown associations with mortality in septic shock and large sepsis cohorts [13,14]. These observations suggest that a composite view of smear morphology could reflect the intensity of inflammation, marrow stress, microvascular injury, and coagulation dysfunction more comprehensively than any single morphological feature. The present study was undertaken to characterize peripheral blood smear abnormalities among adults with sepsis treated at a tertiary-care teaching hospital and to examine whether these abnormalities track with clinical severity and outcomes. The objectives were to determine the frequency of erythrocyte, leukocyte, and platelet smear abnormalities; compare individual smear findings between patients with sepsis without shock and those with septic shock; assess the relationship between the cumulative burden of smear abnormalities and SOFA score, serum lactate, organ-support requirements, acute kidney injury, ICU stay, and mortality; and identify individual smear abnormalities associated with in-hospital death.

Study design and setting: A hospital-based observational study with in-hospital follow-up was conducted at Malla Reddy Institute of Medical Sciences, Hyderabad, Telangana, India. The study period extended from January 2025 to July 2025. Adult patients were evaluated from emergency, medical ward, and intensive care services after a clinical diagnosis of sepsis. Sepsis was defined in accordance with the Sepsis-3 framework as suspected or documented infection associated with acute organ dysfunction, and septic shock was identified using the clinical criteria described by the Sepsis-3 task force [1-3]. SOFA scoring was used to quantify the extent of organ dysfunction [5]. Study participants: Eighty consecutive eligible patients aged 18 years or older were included. Patients were eligible when sepsis was diagnosed during the index hospitalization, a peripheral blood smear and complete blood count were available at or near initial clinical assessment, and the hospital outcome could be ascertained. Patients with known hematological malignancy, primary bone-marrow failure syndromes, recent cytotoxic chemotherapy, established hemolytic disorders likely to independently produce schistocytosis, or incomplete clinical or laboratory records were excluded. The final analytical sample comprised 80 patients. Clinical and laboratory assessment: Demographic variables, comorbid illnesses, presumed source of infection, serum lactate, vasopressor requirement, invasive mechanical ventilation, acute kidney injury, ICU duration, and in-hospital outcome were recorded in a structured data form. Management was provided by the treating clinical teams according to institutional practice and contemporary sepsis recommendations [4]. Venous blood collected in EDTA was used for complete blood count and peripheral smear preparation. Smears were stained using the routine Romanowsky/Leishman method and examined systematically under light microscopy. Morphological variables included anisocytosis, anisopoikilocytosis, polychromasia, schistocytes, NRBCs, neutrophilic leukocytosis, toxic granulation, Döhle bodies, cytoplasmic vacuolization, thrombocytopenia, and giant platelets. The morphological definitions were applied consistently across specimens, with particular attention to toxic neutrophilic changes described in sepsis [6]. Exposure and outcome definitions: For cumulative analysis, patients were categorized according to the number of major smear abnormalities as fewer than three versus three or more abnormalities. The principal severity measures were SOFA score, serum lactate, and presence of septic shock. Clinical outcomes included vasopressor use, mechanical ventilation, acute kidney injury, length of ICU stay, and in-hospital mortality. Mortality status was determined at hospital discharge or death. Statistical analysis: Continuous variables were summarized as mean ± standard deviation, while categorical variables were expressed as frequency and percentage. Comparisons between two groups were performed using the independent-samples t-test for continuous variables and the chi-square test or Fisher exact test for categorical variables, as appropriate. Associations of individual smear findings with septic shock and mortality were evaluated using two-by-two comparisons. A two-sided p value <0.05 was considered statistically significant. Analysis was performed using standard statistical software. Ethical considerations: The study was conducted in accordance with the principles of the Declaration of Helsinki and institutional requirements for research involving human participants. Necessary Permissions were obtained before starting the study.

A total of 80 patients with sepsis were included in the final analysis. The mean age of the study population was 56.3 ± 15.1 years, and 47 (58.8%) patients were male. Diabetes mellitus was present in 30 (37.5%) patients, hypertension in 32 (40.0%), chronic kidney disease in 10 (12.5%), and chronic obstructive pulmonary disease in 8 (10.0%). Respiratory tract infection was the most frequent presumed source of sepsis, accounting for 30 (37.5%) cases, followed by urinary tract infection in 18 (22.5%) and intra-abdominal infection in 14 (17.5%). At presentation, 30 (37.5%) patients had septic shock, while the remaining 50 (62.5%) had sepsis without shock. The mean SOFA score was 8.7 ± 4.2. Overall, 34 (42.5%) patients required vasopressor support, 27 (33.8%) underwent invasive mechanical ventilation, and 28 (35.0%) developed acute kidney injury. In-hospital mortality was 27.5% (22/80). The baseline clinical characteristics and outcomes are summarized in Table 1. Table 1. Demographic, clinical, and outcome characteristics of patients with sepsis (n = 80) Characteristic n (%) / Mean ± SD Age, years 56.3 ± 15.1 Age group, years <40 13 (16.3) 40-59 31 (38.8) ≥60 36 (45.0) Sex Male 47 (58.8) Female 33 (41.3) Diabetes mellitus 30 (37.5) Hypertension 32 (40.0) Chronic kidney disease 10 (12.5) Chronic obstructive pulmonary disease 8 (10.0) Presumed source of sepsis Respiratory tract 30 (37.5) Urinary tract 18 (22.5) Intra-abdominal 14 (17.5) Skin/soft tissue 8 (10.0) Other/undetermined 10 (12.5) Sepsis without shock 50 (62.5) Septic shock 30 (37.5) SOFA score 8.7 ± 4.2 Serum lactate, mmol/L 3.1 ± 2.0 Vasopressor requirement 34 (42.5) Mechanical ventilation 27 (33.8) Acute kidney injury 28 (35.0) ICU stay, days 7.0 ± 4.3 In-hospital mortality 22 (27.5) Values are presented as n (%) unless otherwise indicated. SOFA: Sequential Organ Failure Assessment; ICU: intensive care unit. \Peripheral blood smear examination demonstrated abnormalities involving erythrocytes, leukocytes, and platelets. Anisocytosis was the most frequent erythrocyte abnormality, observed in 47 (58.8%) patients. Anisopoikilocytosis was present in 27 (33.8%), schistocytes in 16 (20.0%), and circulating NRBCs in 14 (17.5%). Among leukocyte abnormalities, neutrophilic leukocytosis was identified in 44 (55.0%) patients, toxic granulation in 38 (47.5%), Döhle bodies in 22 (27.5%), and cytoplasmic vacuolization in 20 (25.0%). Thrombocytopenia was observed in 34 (42.5%) patients. Fourteen (17.5%) patients had no major morphological smear abnormality, 35 (43.8%) demonstrated one or two abnormalities, and 31 (38.8%) exhibited three or more concurrent abnormalities (Table 2). Table 2. Peripheral blood smear abnormalities among patients with sepsis (n = 80) Peripheral smear finding n (%) Red blood cell abnormalities Anisocytosis 47 (58.8) Anisopoikilocytosis 27 (33.8) Polychromasia 14 (17.5) Schistocytes 16 (20.0) Nucleated red blood cells 14 (17.5) White blood cell abnormalities Neutrophilic leukocytosis 44 (55.0) Toxic granulation 38 (47.5) Döhle bodies 22 (27.5) Cytoplasmic vacuolization 20 (25.0) Platelet abnormalities Thrombocytopenia 34 (42.5) Giant platelets 12 (15.0) Number of major smear abnormalities None 14 (17.5) 1-2 abnormalities 35 (43.8) ≥3 abnormalities 31 (38.8) More than one smear abnormality could be present in the same patient. Peripheral smear abnormalities were generally more frequent among patients with septic shock than among those without shock. Toxic granulation was detected in 70.0% of patients with septic shock compared with 34.0% of patients without shock (p = 0.004). Döhle bodies, cytoplasmic vacuolization, thrombocytopenia, schistocytes, and circulating NRBCs were also significantly more frequent in septic shock. Anisocytosis and neutrophilic leukocytosis occurred more often in the shock group, although the differences were not statistically significant (Table 3). Table 3. Association of peripheral blood smear abnormalities with septic shock Smear abnormality Sepsis without shock (n = 50), n (%) Septic shock (n = 30), n (%) p-value Anisocytosis 25 (50.0) 22 (73.3) 0.069 Neutrophilic leukocytosis 24 (48.0) 20 (66.7) 0.164 Toxic granulation 17 (34.0) 21 (70.0) 0.004 Döhle bodies 9 (18.0) 13 (43.3) 0.028 Cytoplasmic vacuolization 8 (16.0) 12 (40.0) 0.033 Thrombocytopenia 15 (30.0) 19 (63.3) 0.007 Schistocytes 6 (12.0) 10 (33.3) 0.043 Nucleated red blood cells 5 (10.0) 9 (30.0) 0.048 Values are n (%). Two-sided p < 0.05 was considered statistically significant. The burden of peripheral smear abnormalities showed a clear relationship with clinical severity. Patients with three or more concurrent smear abnormalities had a significantly higher mean SOFA score than those with fewer than three abnormalities (11.9 ± 3.8 vs. 6.7 ± 3.2; p < 0.001). Mean serum lactate was also higher in the high-burden group (4.1 ± 2.2 vs. 2.5 ± 1.6 mmol/L; p = 0.001). Septic shock occurred in 20 (64.5%) patients with three or more abnormalities compared with 10 (20.4%) patients with fewer abnormalities. Vasopressor requirement, mechanical ventilation, acute kidney injury, and ICU stay were likewise greater in the high-burden group. Mortality was 51.6% among patients with three or more abnormalities compared with 12.2% among those with fewer abnormalities (p < 0.001), as shown in Table 4. Table 4. Relationship between burden of peripheral smear abnormalities and clinical outcomes Parameter <3 abnormalities (n = 49) ≥3 abnormalities (n = 31) p-value SOFA score, mean ± SD 6.7 ± 3.2 11.9 ± 3.8 <0.001 Serum lactate, mmol/L 2.5 ± 1.6 4.1 ± 2.2 0.001 Septic shock 10 (20.4) 20 (64.5) <0.001 Vasopressor requirement 13 (26.5) 21 (67.7) 0.001 Mechanical ventilation 10 (20.4) 17 (54.8) 0.003 Acute kidney injury 12 (24.5) 16 (51.6) 0.025 ICU stay, days 5.9 ± 3.6 8.7 ± 4.8 0.007 In-hospital mortality 6 (12.2) 16 (51.6) <0.001 Values are n (%) unless specified as mean ± SD. ICU: intensive care unit; SOFA: Sequential Organ Failure Assessment. When individual smear abnormalities were examined according to survival status, toxic granulation was observed in 15 (68.2%) non-survivors compared with 23 (39.7%) survivors (p = 0.042). Döhle bodies and cytoplasmic vacuolization were significantly more frequent among non-survivors. The strongest associations with mortality were observed for thrombocytopenia, schistocytes, and circulating NRBCs. Thrombocytopenia was present in 72.7% of non-survivors compared with 31.0% of survivors (p = 0.002); schistocytes were detected in 40.9% versus 12.1% (p = 0.010); and NRBCs were observed in 40.9% versus 8.6% (p = 0.002). Anisocytosis and neutrophilic leukocytosis were numerically more frequent among non-survivors but did not reach statistical significance (Table 5). Table 5. Association of individual peripheral smear abnormalities with in-hospital mortality Smear abnormality Survivors (n = 58), n (%) Non-survivors (n = 22), n (%) p-value Anisocytosis 31 (53.4) 16 (72.7) 0.190 Neutrophilic leukocytosis 29 (50.0) 15 (68.2) 0.227 Toxic granulation 23 (39.7) 15 (68.2) 0.042 Döhle bodies 11 (19.0) 11 (50.0) 0.013 Cytoplasmic vacuolization 10 (17.2) 10 (45.5) 0.021 Thrombocytopenia 18 (31.0) 16 (72.7) 0.002 Schistocytes 7 (12.1) 9 (40.9) 0.010 Nucleated red blood cells 5 (8.6) 9 (40.9) 0.002 Values are n (%). Two-sided p < 0.05 was considered statistically significant. Overall, 58 (72.5%) patients survived to hospital discharge and 22 (27.5%) died. The pattern across analyses demonstrated a progressive relationship between increasing smear abnormality burden and adverse clinical outcomes. Multiple concurrent abnormalities, particularly toxic neutrophilic changes, thrombocytopenia, schistocytosis, and circulating NRBCs, were associated with greater organ dysfunction, septic shock, increased need for organ support, longer ICU stay, and higher in-hospital mortality.

The present study demonstrates that peripheral blood smear morphology is closely linked with clinical severity in sepsis. Nearly four in ten patients had three or more concurrent abnormalities, and this high-burden pattern was associated with higher SOFA scores, serum lactate, septic shock, organ-support requirements, acute kidney injury, longer ICU stay, and mortality. The overall in-hospital mortality of 27.5% reflects the recognized severity spectrum of sepsis and septic shock [1-4]. These findings support systematic smear interpretation as a useful adjunct to conventional clinical and laboratory severity assessment. Toxic neutrophilic changes were prominent. Toxic granulation occurred in 47.5% of the cohort and in 70.0% of patients with septic shock; Döhle bodies and cytoplasmic vacuolization were also significantly associated with shock and mortality. Sharma et al. reported toxic granules in 55.8%, cytoplasmic vacuoles in 30.8%, and Döhle bodies in 17.3% of adults with sepsis, with these features occurring more frequently than in noninfectious SIRS [6]. Our observations extend this association by demonstrating a relationship with clinical severity and death, plausibly reflecting accelerated granulopoiesis and cytokine-driven neutrophil activation during systemic infection. Erythrocyte abnormalities also carried prognostic information. Sepsis produces oxidative injury, membrane remodeling, impaired deformability, and disturbed microvascular passage of red cells [7]. In the current cohort, anisocytosis was common, whereas schistocytes and NRBCs were particularly informative for adverse outcomes. Stachon et al. detected NRBCs in 17.5% of medical ICU patients and reported substantially greater mortality among NRBC-positive patients [8]. Desai et al. similarly linked detectable NRBCs with increased ICU and hospital mortality in surgical sepsis [9]. Our NRBC prevalence was 17.5%, and the finding occurred in 40.9% of non-survivors compared with 8.6% of survivors, reinforcing its value as a marker of severe physiological and marrow stress. Thrombocytopenia was present in 42.5% of patients and showed strong associations with septic shock and mortality. Earlier studies identified thrombocytopenia, persistent platelet decline, and failure of platelet recovery as adverse prognostic indicators [10,11]. In the present study, nearly three-quarters of non-survivors were thrombocytopenic. The parallel association of schistocytes with shock and death is biologically consistent with sepsis-associated coagulopathy, endothelial injury, platelet consumption, and microangiopathic red-cell fragmentation. Current concepts of sepsis-associated disseminated intravascular coagulation emphasize interactions between inflammation, coagulation activation, endothelial dysfunction, and impaired fibrinolysis [12]. Concurrent thrombocytopenia and schistocytosis can therefore identify a severe hematologic phenotype. The frequent anisocytosis in this cohort also agrees with evidence that erythrocyte heterogeneity accompanies systemic inflammation and poor prognosis. Red cell distribution width, an automated measure of variation in erythrocyte size, has been associated with mortality in septic shock and large sepsis cohorts [13,14]. Although anisocytosis on smear is not interchangeable with red cell distribution width, both reflect disturbed erythrocyte homeostasis. Overall, the present findings indicate that readily available morphological information can complement SOFA scoring and routine laboratory tests, especially when multiple abnormalities are interpreted together rather than as isolated findings. Limitations This study has several limitations. It was conducted at a single tertiary-care institution with a modest sample of 80 patients, which restricts external generalizability. Smear interpretation contains an observer-dependent component, and interobserver agreement was not quantified. Serial smear changes were not evaluated. Potential confounders such as transfusion exposure, nutritional anemia, coagulation profiles, microbiological etiology, and treatment timing were not incorporated into multivariable models.

Peripheral blood smear abnormalities were common in patients with sepsis and showed a clear association with disease severity and hospital outcomes. A burden of three or more abnormalities identified patients with higher SOFA scores, greater lactate concentrations, more septic shock, increased vasopressor and ventilatory requirements, acute kidney injury, longer ICU stay, and markedly higher mortality. Toxic granulation, Döhle bodies, cytoplasmic vacuolization, thrombocytopenia, schistocytes, and circulating nucleated red blood cells were especially linked with adverse outcomes. Routine, systematic smear examination therefore offers a low-cost adjunct to clinical severity assessment. Its greatest value lies in complementing established scores and laboratory parameters rather than replacing them in routine sepsis risk stratification decisions overal

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