An epidural needle is typically long and thin to reach the epidural space in the spine.
- Length: The needle length usually ranges from about 9 to 11 cm (approximately 3.5 to 4.3 inches), with some variation depending on the patient's body size. For example, a normal-weight adult might have a needle length around 3.5 inches, while an obese adult might require a needle up to 6 inches long
- Gauge (Thickness): The common needle sizes used for epidurals are 16G, 17G, and 18G for catheter insertion, with 17G and 18G being the most typical sizes. The gauge number indicates the diameter, where a higher gauge means a thinner needle. For example, 18G needles are about 1.2 mm in diameter, 17G about 1.4 mm, and 16G about 1.6 mm
- Physical description: Despite being long, the needle is very thin-about four times the width of a human hair. The catheter inserted through the needle is even thinner, roughly the width of a pencil lead
In summary, an epidural needle is around 9-11 cm long and typically 16-18 gauge in thickness, making it long enough to reach the epidural space but thin enough to minimize discomfort during insertion.
