The most common method of pain relief during labor and delivery is the epidural block. It is used to provide pain relief during labor, vaginal delivery, or cesarean section. The block is achieved by injecting a locally acting anesthetic drug into the epidural space (located just outside the lining covering the spinal cord). When given in smaller doses for pain relief, the drug effectively blocks pain sensations from reaching the spinal cord through that portion of the epidural space. Larger doses are necessary for anesthesia during surgical procedures such as cesarean section.
A needle is inserted through the skin, between the vertebrae, and into the epidural space. To widen the opening between the vertebrae for better access to the epidural space, the patient is placed in a curled position. Sometimes just a single dose of anesthetic drug is injected through the needle; more commonly, though, a catheter (a small tube) is inserted through the needle and passed into the epidural space. The needle is removed while the catheter remains in place so that medication may be given as required without further injections. This is referred to as continuous epidural analgesia. Recently, some hospitals have introduced patient-controlled continuous epidural analgesia. Similar to patient-controlled intravenous pain relief, this method uses a device that is programmed to give a certain dose of medication on patient demand. A lockout period is programmed into the device to control how often the patient can self-medicate. In addition to the doses that the patient can demand, a lower underlying dose is usually administered continuously.
The medications used in epidural blocks are local anesthetics that work only at the site of injection. There are several medicines that can be used in epidural blocks and they differ in how long they act and their risk of adverse effects. The amount of anesthetic used depends on the stage of labor during which the block is placed. During the first stage of labor, a smaller amount may be used to provide only pain relief; during the latter part of the second stage, especially when surgery may be necessary, more medication is used to provide anesthesia.
Lumbar Versus Caudal
An epidural block can be placed anywhere along the spinal cord. In laboring patients, the blockade is placed either in the lumbar region (the region of the lower back) to block the pain of contractions of the uterus and dilation of the cervix, or in the sacral or caudal region (lower still) to block the pain of the stretching of pelvic floor tissues. Caudal blocks are reserved mainly for forceps or vacuum deliveries.
Who Should Have an Epidural?
A woman who desires pain relief during labor should talk with her doctor about receiving an epidural block. Epidural block is the method of choice for many women because it is effective and safe for both mother and baby. In addition, epidurals result in total or near total pain relief without altering consciousness and orientation.
Certain women should have epidural blocks for medical or obstetric reasons. These include women with the following potential problems:
- a history of malignant hyperthermia (an adverse reaction to general anesthesia);
- certain forms of heart and lung diseases;
- treatment of autonomic hyperreflexia in women with a spinal cord injury; and
Who Should Not Have an Epidural?
Some woman should not have an epidural block because of health concerns. These include women who:
- refuse or are unable to cooperate;
- have increased pressure in the brain secondary to a tumor or collection of blood;
- have an infection at the site of needle placement; and
- have a bleeding disorder (or take anticoagulation medicine), low blood pressure, or low body-water content.