A patient following a skid resulting in a motor traffic accident was brought to the emergency room 2 hours later. On examination, he was stable with GCS 15/15. The pupil was reactive to light. Tenderness and bruising over the left lower chest wall with petechiae was seen. Severe tenderness was elicited in the left hypochondriac region and BP- 90/50 mm of Hg. What is the best investigation used in the ER? GCS: Glasgow coma scale FAST: Focused Assessment with Sonography for Trauma

Correct Answer: A. FAST

In a haemodynamically unstable trauma patient (BP 90/50) with signs of blunt abdominal trauma (left hypochondriac tenderness, bruising, petechiae), FAST (Focused Assessment with Sonography for Trauma) is the gold standard first-line investigation in the emergency room. This patient has classic features of splenic injury—left lower chest wall trauma with severe left hypochondriac tenderness and hypotension suggesting intra-abdominal bleeding. FAST is a rapid, non-invasive, bedside ultrasound protocol that detects free fluid (blood) in four key areas: perihepatic (Morrison's pouch), perisplenic, pelvic, and pericardial. It takes 2–5 minutes, requires no patient transport, and can be performed simultaneously with resuscitation. In unstable patients, FAST guides immediate clinical decisions: positive FAST + hypotension = indication for emergency surgery or interventional radiology. The patient's GCS 15/15 and reactive pupils rule out significant head injury requiring CT priority. FAST sensitivity for detecting haemoperitoneum is 73–100% depending on operator experience and free fluid volume; in Indian trauma centres, it is increasingly the standard of care per ATLS guidelines and Indian Trauma Society protocols.

Why the other options are wrong

B. CT scan — CT is the gold standard for detailed anatomical diagnosis in stable trauma patients, but this patient is haemodynamically unstable (BP 90/50). CT requires transport out of the resuscitation area, takes 10–20 minutes, and delays life-saving interventions. In unstable patients, CT is contraindicated until haemorrhage control is achieved. CT is reserved for stable patients or post-resuscitation imaging. C. X-ray — Plain X-ray (chest/abdomen) has low sensitivity for detecting free intra-abdominal fluid and solid organ injury. It may show rib fractures or pneumothorax but does not guide immediate surgical decisions in haemodynamically unstable patients. X-ray is too slow and non-specific for acute haemorrhage assessment; it delays definitive management. D. Diagnostic peritoneal lavage — DPL was the historical gold standard before FAST became available. However, DPL is invasive, takes longer than FAST, cannot be repeated easily, and has higher morbidity (bowel perforation, infection). DPL is now obsolete in most Indian trauma centres; FAST has replaced it as the rapid bedside test for haemoperitoneum in unstable patients.

High-Yield Facts

Mnemonics

FAST Protocol – Four Zones Morrison's pouch (perihepatic) | Perisplenic | Pelvic | Pericardial. Remember: Morrison = right upper quadrant (hepatic injury), Perisplenic = left upper quadrant (splenic injury, as in this case). When to FAST vs CT UNSTABLE (BP <90) → FAST first (bedside, 5 min). STABLE (BP >90, normal exam) → CT (detailed anatomy). This patient is unstable (BP 90/50) → FAST is correct.

NBE Trap

NBE may lure students who memorise "CT is gold standard for trauma" into choosing CT, forgetting that gold standard applies only to stable patients. The hypotension (90/50) is the key discriminator that shifts the answer to FAST.

Clinical Pearl

In Indian emergency departments, FAST has become the standard of care for unstable trauma patients because it avoids transport delays and guides immediate surgical decisions. A positive FAST in a hypotensive patient with left-sided trauma is a red flag for splenic rupture—the most common solid organ injury in blunt abdominal trauma in India.

_Reference: Harrison Ch. 295 (Trauma); ATLS Manual (American College of Surgeons); Indian Trauma Society Guidelines on Blunt Abdominal Trauma_