Bruising is the most frequently observed complication occurring at 30% of puncture sites. In most, it is mild but in some you could encounter large bruises. The bruising is more common at the radial site. The brachial and femoral arteries lie deep, and this may account for less frequently observed bruising at these sites.

References:

Gillies IDS, et al. The nature and incidence of complications of peripheral arterial puncture. Anesthesia 1979; 34:506-9.

A hematoma can occur at the puncture site in patients on anticoagulation. Serious retro peritoneal hemorrhage has been reported. The hematoma formation in anticubital fossa is tolerated poorly and can result in median nerve compression and ischemic changes secondary to compression of the artery.

References:

Neviaser RJ, et al. Complications of arterial puncture in anticoagulated patients. The Jour of Bone and Joint Surg 1976; 58A:218-220.

• Avoid arterial punctures in patients with a coagulation defect. 
• Avoid femoral and brachial artery where the hematoma cannot be easily recognized and complications are worse. 
• The thinner the needle, the less the risk of bleeding. Apply compression of the vessel for five minutes.

These steps will help you to minimize the occurrence of bruising and hematoma following an arterial puncture.