Urinalysis is critical in evaluating and treating patients with urinary tract infections or complex urosepsis. Ultrasound guidance for suprapubic bladder catheterization shows improved success rates, decreased number of attempts, and decreased complications. Ultrasound guidance for placement of central venous catheters (CVCs) is one of the most important uses of ultrasound in the clinical setting. Undetected foreign bodies during initial ED visits may lead to complications, including inflammatory reaction, infection, delayed wound healing, poor cosmetic outcome, and, less often, life-threatening illness. Therapeutic thoracentesis is performed when patients are symptomatic due to an effusion. Pneumothorax is the major complication associated with thoracentesis. Lumbar puncture (LP) is one of the most frequently performed procedures in the acute care setting. The amount of peritoneal fluid in patients requiring therapeutic paracentesis may be large enough that ultrasound is not necessary. Unrecognized pericardial tamponade is one of the most quickly fatal pathological entities in medicine.