Emergency and Trauma · Ultrasound

Emergency Ultrasound and Point-of-Care Imaging One-Liners

High-yield one-liners on emergency and point-of-care ultrasound including eFAST, RUSH examination, biliary assessment and procedural guidance.

Rapid-revision one-liners covering emergency and point-of-care ultrasound (POCUS), including eFAST, RUSH examination, focused biliary assessment and ultrasound-guided procedures in the emergency setting.

eFAST purpose
eFAST (extended Focused Assessment with Sonography for Trauma) rapidly identifies free fluid in four peritoneal windows, pericardial effusion and pneumothorax in the trauma bay within 2-3 minutes.
Morison pouch sensitivity
The right upper quadrant (Morison pouch) is the most sensitive eFAST window for detecting free peritoneal fluid; approximately 200-250 mL of fluid is needed for reliable detection.
Pericardial effusion on subxiphoid view
Subxiphoid four-chamber view identifies pericardial effusion; tamponade physiology is suggested by right atrial systolic collapse, right ventricular diastolic collapse and IVC plethora.
Pneumothorax on lung ultrasound
Absence of lung sliding, absent comet-tail artefacts and a barcode pattern on M-mode indicate pneumothorax; the lung point sign (transition between sliding and absent sliding) is 100% specific.
RUSH examination
RUSH (Rapid Ultrasound in Shock) evaluates the pump (cardiac function), the tank (IVC, pericardium, pleura, peritoneum) and the pipes (aorta, DVT) to identify the cause of undifferentiated shock.
IVC collapsibility for volume assessment
IVC diameter and respiratory collapsibility estimate right atrial pressure; a plethoric IVC (>2.5 cm, <50% collapse) suggests elevated CVP, while a small, collapsible IVC suggests hypovolaemia.
Focused biliary ultrasound
In suspected biliary colic or cholecystitis, assess gallbladder wall thickness (>3 mm), pericholecystic fluid, sonographic Murphy sign and gallstones; CBD >6 mm (or >8 mm post-cholecystectomy) suggests obstruction.
Hydronephrosis in renal colic
Point-of-care ultrasound identifies hydronephrosis as an indirect sign of ureteric obstruction; sensitivity is moderate (approximately 60-80%) but specificity is high when combined with clinical presentation.
AAA screening in emergency
Bedside aortic ultrasound measures infrarenal aortic diameter; diameter >3 cm is aneurysmal. In a haemodynamically unstable patient with known or suspected AAA, positive FAST with aneurysm warrants immediate surgical consultation.
Ectopic pregnancy POCUS
Transvaginal or transabdominal POCUS showing an empty uterus with positive pregnancy test and free peritoneal fluid is treated as ruptured ectopic pregnancy until proven otherwise.
Ultrasound-guided vascular access
Real-time ultrasound guidance for central venous access reduces arterial puncture, haemothorax and catheter misplacement; the internal jugular vein is assessed in Trendelenburg with linear or curvilinear probe.
Paracentesis and thoracentesis guidance
Ultrasound guidance for paracentesis and thoracentesis reduces complications; mark the puncture site with the patient in the procedural position and confirm fluid depth >1 cm.
Fracture identification with POCUS
Point-of-care ultrasound can identify cortical discontinuity in rib, long-bone and pelvic fractures; sensitivity for rib fractures exceeds that of supine chest radiograph.
Foreign body localisation
High-frequency linear probe ultrasound identifies radiolucent foreign bodies (wood, glass, plastic) not visible on radiograph; hyperechoic focus with posterior shadowing or reverberation artefact.
POCUS limitations
POCUS is operator-dependent and should not replace definitive imaging (CT) when clinical suspicion is high; a negative eFAST does not exclude significant intra-abdominal injury.

Caution

POCUS is a focused, time-critical assessment tool. Findings must be integrated with clinical context and confirmed by definitive imaging where appropriate. Operator experience significantly affects diagnostic accuracy.

Exam pearl

In viva, always state the clinical question being answered by POCUS (e.g., 'Is there free fluid?', 'Is there pericardial tamponade?') and acknowledge its limitations as a screening rather than definitive diagnostic tool.

Viva questions

What are the components of the RUSH examination?
RUSH evaluates three categories: the pump (cardiac contractility, pericardial effusion, RV size), the tank (IVC volume status, pericardial fluid, pleural effusion, peritoneal free fluid), and the pipes (aortic diameter for aneurysm, deep veins for DVT). It systematically identifies the cause of undifferentiated shock.
What is the lung point sign and why is it important?
The lung point sign is the location where normal lung sliding intermittently returns at the boundary of a pneumothorax on real-time ultrasound. It is 100% specific for pneumothorax and helps confirm the diagnosis when lung sliding is absent.
What is the minimum volume of free fluid detectable by eFAST?
Approximately 200-250 mL of free peritoneal fluid is needed for reliable detection in the most dependent windows. Smaller volumes may be missed, particularly in the supine trauma patient.
Why should a negative eFAST not exclude intra-abdominal injury?
eFAST has limited sensitivity for small-volume haemorrhage, retroperitoneal injuries, hollow viscus perforation and early solid-organ contusions. It is a rapid screening tool and must be supplemented by CT when clinical suspicion persists.
What ultrasound findings suggest acute cholecystitis?
Gallbladder wall thickening greater than 3 mm, pericholecystic fluid, impacted gallstone in the neck, sonographic Murphy sign (focal tenderness over the gallbladder) and gallbladder distension. No single sign is diagnostic; the combination increases specificity.

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