Pudendal block is a local anesthesia procedure used for impending perineal laceration or indicated episiotomy during the birth process. The pain of the expectant mother is supposed to be relieved by blocking the sensitive pudendal nerve. Meanwhile, peridural anesthesia is usually used instead of pudendal blockade.
What is pudendal block?
The pudendal nerve originates from the sacral plexus and contains spinal nerves of spinal cord segments S1 to S4. Thus, it carries somatomotor as well as general somatosensitive fibers that conduct pain signals to the central nervous system. The nerve can become clinically relevant during the birth process. With the so-called pudendal block or pudendal anesthesia, obstetricians block the pain-conducting pathways on the pudendal nerve. The block is used primarily during the expulsion phase and relieves pain associated with the perineal incision or perineal tears in the external birth canal or vulva-perineal region. Accordingly, the pudendal block is a method of anesthesia that plays a role primarily for obstetrics and facilitates the natural birth process for childbearing women. Medical literature uses the term pudendal block synonymously with the term pudendal block.
Function, effect, and goals
The pudendal block mist be used in suction cup births or forceps births. When using instruments such as forceps or the suction cup, there is an increased risk of puncturing the baby’s head. To protect the unborn child, an episiotomy usually takes place during forceps and suction cup deliveries. The so-called episiotomy is also used for twin births, threatened perineal rupture and premature births. In order to spare the woman in labor severe pain, peridural anesthesia may be used instead of the pudendal block for the above indications. In the recent past, therefore, peridural anesthesia has largely replaced the pudendal block, although the block was used regularly until the previous century. The pain conduction of the pudendal nerve is inhibited during the pudendal block. Pain sensations in the perineal area, the vaginal region and the pelvic floor area can thus no longer reach the central nervous system of the woman giving birth. Although the pain is registered by the nociceptors in these areas and converted into bioelectrical excitation, it does not enter the birthing woman’s consciousness due to the blockade of the afferent pathways (pathways ascending into the central nervous system). Despite the anesthesia, the expectant mother’s urge to push does not subside. The labor pain persists during anesthesia. The ischial spine serves as a reference point for the pudendal nerve. The anatomical structure can be palpated by palpation of the vaginal area. The physician or obstetrician uses a long cannula to apply a local anesthetic in the area of the ischial spine to several lateral sites of the vagina. The application is made to the right and left sides of the vaginal wall. Minutes after the application, the anesthesia sets in. The exit of the vagina, the labia and the perineum are largely insensitive to pain when anesthesia sets in. In principle, the effect of the pudendal block lasts for about an hour. During this hour, the doctor not only makes the perineal incision, but also sutures the perineal incision.
Risks, side effects and dangers
The pudendal block has now been almost completely replaced by the peridural anesthesia. Peridural anesthesia is a variation of central line anesthesia. Using a cannula, the physician injects a local anesthetic or opioid analgesic into the peridural area of the spine. This procedure shuts down pain conduction in a central manner and blocks all nerves that run through the peridural space. Peridural anesthesia has supplanted the pundendal block for a variety of reasons. One of the most important reasons is the unreliability of the block. Most women report relief of pain after a pudendal block but do not claim to have experienced complete freedom from pain. In addition, for a large proportion of all women giving birth, the pudendal block has an effect on only one side or, in extreme cases, does not work at all. The risks and side effects are balanced for pudendal block and epidural anesthesia.In principle, local anesthetics are associated with a much lower risk than general anesthetics. The drugs used only act within a limited area and do not enter the entire body. However, if larger amounts of the active ingredients enter the blood circulation system, a systemic effect can occur. If the anesthesiologist accidentally hits a vein or a region with a strong blood supply, a transfer into the bloodstream is likely. Complications in this case can include seizures as well as severe cardiac arrhythmias, which can affect not only the mother but also the unborn child during the birth process. Artificial respiration of the parturient and, in extreme cases, an emergency cesarean section may be required to save the mother and child in the event of systemic effects of local anesthetics. In addition, allergic reactions sometimes occur as complications of local anesthetics. These rare side effects manifest themselves, for example, in the form of itching or reddening of the skin. In extreme cases, respiratory distress or even circulatory failure occurs. The injection site may also become inflamed after application of the anesthetic. Infections are rare in the current state of Western medicine, but still cannot be completely ruled out. Especially during peridural anesthesia, the patient’s blood pressure often drops. In the meantime, pre-infusions can prevent this drop in blood pressure. Because the unborn child may come into contact with the local anesthetic via the umbilical cord during both pudendal block and peridural anesthesia, it is essential to weigh the benefits and risks before application.
