## Clinical Context This patient has a positive FAST examination (free fluid in left paracolic gutter and pelvis) consistent with intra-abdominal bleeding, likely from splenic injury given the left upper quadrant tenderness. He is **hemodynamically stable** (BP 110/72, HR 102/min — mild tachycardia acceptable in trauma). ## FAST and Hemodynamic Stability — The Decision Algorithm **Key Point:** In a hemodynamically **stable** patient with a positive FAST, the next step is **CT abdomen and pelvis with IV contrast** — NOT immediate laparotomy and NOT simple observation. CT provides injury grading, identifies the source of bleeding, and guides non-operative vs. operative management. **High-Yield (ATLS 10th Edition):** The management algorithm for blunt abdominal trauma is: - **Hemodynamically UNSTABLE + Positive FAST** → Immediate exploratory laparotomy - **Hemodynamically STABLE + Positive FAST** → CT abdomen/pelvis with IV contrast to characterize injury ## Why CT Is the Correct Next Step 1. **Injury grading is essential** — Splenic injury grade (AAST I–V) determines whether angioembolization, operative management, or NOM is appropriate. A grade IV–V injury may require intervention even in a currently stable patient. 2. **Identifies other injuries** — CT detects hollow viscus injury, mesenteric tears, retroperitoneal hematoma, and other solid organ injuries that FAST cannot characterize. 3. **Guides definitive management** — Without CT grading, the clinician cannot safely commit to NOM. Observation alone (Option C) without CT is insufficient because it delays identification of high-grade injuries requiring intervention. 4. **Patient is stable enough for CT** — BP 110/72 and HR 102 represent compensated hemodynamics; transport to CT is safe. ## Management Algorithm ``` Positive FAST | ├── Hemodynamically UNSTABLE → Immediate Laparotomy (Option D) | └── Hemodynamically STABLE → CT Abdomen/Pelvis with IV Contrast (Option A) | ┌──────────────┴──────────────┐ Low-grade injury High-grade injury → NOM + monitoring → Angioembolization or OR ``` ## Why the Other Options Are Incorrect | Option | Reason Incorrect | |---|---| | **B — DPL** | Obsolete in modern trauma; replaced by FAST and CT (ATLS 10th Ed.) | | **C — Observe + serial exam only** | Insufficient without CT grading; misses high-grade injuries requiring intervention | | **D — Immediate laparotomy** | Reserved for hemodynamically UNSTABLE patients with positive FAST; this patient is stable | **Clinical Pearl:** "Observation alone" (Option C) is appropriate only AFTER CT has confirmed a low-grade solid organ injury amenable to NOM. Skipping CT in a positive-FAST stable patient is a management error — it denies the surgeon critical information about injury severity. **High-Yield:** FAST is a screening tool; CT is the definitive diagnostic step in stable patients. The positive FAST tells you *that* there is free fluid; CT tells you *why* and *how much*. [cite: ATLS 10th Edition, Chapter 5 — Abdominal and Pelvic Trauma; Feliciano DV, Mattox KL, Moore EE — Trauma, 8th Edition] 
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