# A 3-year-old toddler with a recent episode of bloody diarrhea is admitted to the pediatric unit with suspected hemolytic-uremic syndrome (HUS). Which assessment finding would be most indicative of this condition? > source: MyMerci (mymerci.kr) > url: https://mymerci.kr/pages/nclex_q.php?qn_id=542531 > language: ko > subject: Child Health ## 문제 A 3-year-old toddler with a recent episode of bloody diarrhea is admitted to the pediatric unit with suspected hemolytic-uremic syndrome (HUS). Which assessment finding would be most indicative of this condition? The nurse is caring for a 4-year-old child with suspected hemolytic-uremic syndrome following a recent episode of bloody diarrhea. ## 보기 1. Elevated white blood cell count with a left shift on differential 2. Hypertension accompanied by peripheral and periorbital edema 3. Decreased platelet count with scattered petechiae on the skin 4. Schistocytes on peripheral blood smear with decreased hematocrit **✔ 정답** **정답: 4** ## 해설 HUS is characterized by the classic triad of hemolytic anemia, thrombocytopenia, and acute kidney injury. Schistocytes on peripheral blood smear with decreased hematocrit is the most specific finding, indicating microangiopathic hemolytic anemia. ## 심화 해설 Understanding Hemolytic-Uremic Syndrome (HUS) Hemolytic-uremic syndrome is a thrombotic microangiopathy (TMA) characterized by a classic triad of clinical and laboratory findings. The condition is most often triggered by Shiga toxin-producing bacteria following a gastrointestinal infection, leading to endothelial injury, particularly in the kidneys. The primary pathological process involves the formation of microthrombi in small blood vessels, which consumes platelets and mechanically damages red blood cells as they pass through narrowed, clot-filled vessels [1][4]. Analysis of the Correct Answer (Option 4) The assessment finding most indicative of HUS is schistocytes on peripheral blood smear with decreased hematocrit. This finding directly reflects the core component of microangiopathic hemolytic anemia (MAHA), which is a defining feature of the HUS triad [1][3]. Schistocytes are fragmented red blood cells created by the mechanical shearing force exerted on erythrocytes as they traverse platelet-rich microthrombi in the microvasculature. The destruction of these red blood cells (hemolysis) leads directly to a decreased hematocrit. This is not just a supportive lab value; it is a direct visualization of the underlying disease mechanism [4]. Why Other Options Are Less Indicative - **Option 1:** An elevated white blood cell count with a left shift is a non-specific marker of inflammation or infection. While a preceding bacterial gastroenteritis is common in typical HUS, this finding is not a defining characteristic of the syndrome itself, which is defined by the triad of hemolytic anemia, thrombocytopenia, and acute kidney injury [1]. - **Option 2:** Hypertension accompanied by peripheral and periorbital edema is a classic presentation of acute glomerulonephritis or nephrotic syndrome, often related to fluid overload and sodium retention from primary kidney dysfunction. While acute kidney injury is a component of HUS, the edema in HUS is more directly related to oliguric renal failure, and this presentation is not as pathognomonic as the hematologic findings. The core problem in HUS is the microangiopathy, not a primary glomerular inflammatory process [1][2]. - **Option 3:** A decreased platelet count with scattered petechiae is a very common finding in HUS and represents the thrombocytopenia component of the triad [1][2]. However, thrombocytopenia alone is not the most specific indicator. Many conditions, such as immune thrombocytopenic purpura (ITP), can cause low platelets and petechiae without the microangiopathic hemolytic anemia that defines HUS. The presence of schistocytes confirms that the thrombocytopenia is due to consumption in microthrombi (a TMA process), not just immune destruction or underproduction. Clinical Integration and Diagnostic Significance For a definitive diagnosis of HUS, you must see evidence of the full triad. While thrombocytopenia (Option 3) and acute kidney injury (which could manifest as the edema in Option 2) are essential, the presence of schistocytes on a peripheral smear with a falling hematocrit is the most specific finding that distinguishes a thrombotic microangiopathy like HUS from simple hemolysis or isolated platelet disorders. The schistocyte is the hallmark laboratory evidence of mechanical red cell destruction, confirming the microangiopathic process. A decreased hematocrit is the direct consequence of this hemolysis, and together they represent the non-immune, mechanical hemolytic anemia that is central to the syndrome's pathophysiology [3][4]. References (research sources) - [1]Hemolytic Uremic SyndromeResearch articleRout P, Daley SF. (2026) - [2]Hemoglobinuria-associated acute kidney injury in hemolytic uremic syndrome without renal thrombotic microangiopathy.Research articleMancianti N, Jingjing L, Tripodi SA, Guarnieri A, Garosi G. (2026) · DOI: 10.1186/s12882-026-04887-0 - [3]Delayed-Onset Hemolysis in a Case of Hemolytic Uremic Syndrome: A Diagnostic Challenge.Case reportYounas M, Fatima N, Naveed Z, Nafisa S. (2026) · DOI: 10.1155/crh/2941212 - [4]<i>N</i>-Acetyl-<i>L</i>-Cysteine as a Potential Adjunctive Strategy in STEC-HUS: Mechanistic Rationale and Current Evidence.Research articleWróblewska J, Wróblewski M, Woźniak A. (2026) · DOI: 10.3390/molecules31132264 ## 임상 시나리오 Recognizing the HUS TriadKey laboratory findings for diagnosis The classic triad of Hemolytic-Uremic Syndrome consists of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. The most direct evidence of the hemolytic process is the presence of schistocytes on a peripheral blood smear, which mechanically confirms red blood cell fragmentation. A decreased hematocrit reflects the degree of hemolysis. While thrombocytopenia is also part of the triad, isolated petechiae are less common; platelets are consumed in microthrombi rather than causing primary skin bleeding. Hypertension and edema are more suggestive of other renal pathologies like acute glomerulonephritis. CautionDo not confuse the thrombocytopenia of HUS with Immune Thrombocytopenic Purpura (ITP). In HUS, platelet transfusion is generally avoided unless there is active bleeding or an invasive procedure is required, as it may worsen microthrombi formation. ## 핵심 개념 - **Schistocytes** — Fragmented red blood cells resulting from mechanical shearing as they pass through platelet-rich microthrombi in the microvasculature, a hallmark of microangiopathic hemolytic anemia. - **Hemolytic-Uremic Syndrome (HUS)** — A thrombotic microangiopathy characterized by the classic triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury, often triggered by Shiga toxin-producing E. coli. - **Microangiopathic Hemolytic Anemia (MAHA)** — A type of hemolytic anemia caused by physical destruction of red blood cells within small blood vessels due to microthrombi, leading to the presence of schistocytes and a decreased hematocrit. - **Thrombotic Microangiopathy (TMA)** — A pathological process involving endothelial injury and formation of platelet-rich microthrombi in arterioles and capillaries, consuming platelets and damaging red blood cells. - **Shiga Toxin** — A bacterial toxin produced by Shigella dysenteriae or certain E. coli strains that damages vascular endothelial cells, initiating the cascade of events leading to typical HUS. ## 같은 주제 문제 - [A 3-year-old toddler is admitted to the pediatric unit with suspected hemolytic-uremic syn…](https://mymerci.kr/pages/nclex_q.php?qn_id=542532) - [A 5-year-old child with hemolytic-uremic syndrome (HUS) is admitted to the pediatric inten…](https://mymerci.kr/pages/nclex_q.php?qn_id=542533) - [A 4-year-old child with hemolytic-uremic syndrome (HUS) is admitted to the pediatric inten…](https://mymerci.kr/pages/nclex_q.php?qn_id=542534) --- More free questions: [기출문제](https://mymerci.kr/) _학습 참고용입니다. 실제 임상은 최신 지침과 소속 기관 프로토콜을 따르세요._