An epidural is given by threading a thin, flexible catheter into the space just outside your spinal cord’s protective membrane, then delivering pain-relieving medication through it. The entire insertion process takes about 10 to 15 minutes from start to finish. Here’s what happens at each step.
How You’ll Be Positioned
Before anything touches your back, you’ll be asked to get into one of two positions: sitting up on the edge of the bed and curling forward, or lying on your side in a fetal position. Both accomplish the same goal. Curling your body forward opens up the small gaps between the bones in your lower spine, giving the anesthesiologist a wider target to work with. You’ll be asked to round your back as much as possible, tucking your chin toward your chest and pushing your lower spine outward. If you’re in labor, a nurse or partner will typically help you hold the position steady through contractions.
Numbing the Skin
Once your back is cleaned with an antiseptic solution, the anesthesiologist injects a small amount of local anesthetic into the skin and tissue just beneath it. This is the only sharp sting you should feel during the entire procedure. It creates a numb patch about the size of a coin in your lower back, so the larger epidural needle can pass through without pain. After that initial sting, most people report feeling only pressure or pushing sensations for the rest of the process.
What the Needle Does
The epidural needle is a specialized hollow needle called a Tuohy needle. It’s typically 10 centimeters long (about 4 inches) and comes in either 16 or 18 gauge, roughly the diameter of a small finishing nail. The tip has a slight curve to it, which helps guide the catheter in the right direction once it’s in place.
The needle passes through several layers of tissue on its way to the epidural space: first the skin and the fatty tissue beneath it, then a series of tough ligaments that connect your vertebrae together. The final and thickest of these is the ligamentum flavum, a dense band of tissue that sits right in front of the epidural space. Reaching this layer is a key moment in the procedure because the epidural space is just on the other side.
How the Anesthesiologist Knows They’re in the Right Spot
The epidural space is only a few millimeters wide, so finding it requires a precise technique. As the needle advances through the ligaments, the anesthesiologist attaches a syringe filled with either saline or air and applies gentle, continuous pressure to the plunger. The dense ligament tissue resists this pressure, making the plunger hard to push. The moment the needle tip passes through the ligamentum flavum and enters the epidural space, that resistance suddenly disappears and the plunger glides forward easily. This is called the “loss of resistance” technique, and it’s the primary way clinicians confirm proper needle placement.
This step requires a trained sense of touch. The anesthesiologist is feeling for subtle changes in resistance through the syringe, advancing the needle fractions of a millimeter at a time.
Threading the Catheter
The needle itself doesn’t stay in your back. It serves as a temporary guide for a soft, flexible catheter (a thin plastic tube) that gets threaded through the hollow center of the needle and into the epidural space. The catheter is advanced about 4 to 5 centimeters past the needle tip into the epidural space. Keeping it under 6 centimeters reduces the chance of the catheter drifting into a blood vessel.
Once the catheter is in position, the needle is carefully withdrawn, leaving only the catheter behind. The anesthesiologist tapes the catheter securely to your back, running it up and over your shoulder so it won’t be pulled or dislodged when you move. A small test dose of medication is given first to confirm the catheter isn’t in a blood vessel or in the spinal fluid itself. If everything checks out, the full dose follows.
What It Feels Like as It Takes Effect
After the medication starts flowing, you’ll typically notice a warm, tingling sensation spreading through your lower body within a few minutes. Full pain relief usually builds over 10 to 20 minutes. The goal in labor epidurals is to block pain signals while still allowing you to feel pressure, so you’re aware of contractions even if they no longer hurt. Your legs will feel heavy and may be difficult to move, but you shouldn’t be completely paralyzed from the waist down with modern dosing.
The catheter stays in place for as long as pain relief is needed, sometimes hours during labor. Medication can be delivered continuously through a pump, or you may be given a button that lets you administer small additional doses yourself when you feel the pain returning.
What Happens to Your Body Afterward
One of the most common effects after an epidural takes hold is a drop in blood pressure. The same nerves that carry pain signals also help regulate blood vessel tone, so blocking them can cause blood vessels to relax and widen. This is why your blood pressure will be checked frequently in the first 15 to 20 minutes after the medication starts, and periodically after that. Intravenous fluids are typically given beforehand to help offset this effect.
Your baby’s heart rate will also be monitored continuously, since a significant drop in your blood pressure can temporarily reduce blood flow to the placenta. In most cases, any blood pressure changes are mild and easy to manage.
When an Epidural Doesn’t Work Perfectly
Epidurals are effective for the majority of patients, but they don’t always provide complete or even pain relief. Between 10 and 20 percent of women in labor experience inadequate pain relief from their epidural, according to the European Society of Anaesthesiology and Intensive Care. This can mean pain that breaks through on one side of the body, patchy areas that remain sensitive, or a block that wears off too quickly.
When this happens, the anesthesiologist has several options. Repositioning you so gravity helps the medication spread more evenly is often the first step. The catheter can be pulled back slightly or an additional bolus of medication given. If the block remains inadequate, the catheter may be removed and replaced with a new one. A complete failure requiring an entirely new epidural is less common than a partial block that can be adjusted.