Randomized Double Blind Clinical Trial on the Effect of Levobupivacaine Infiltration Versus Placebo on the Post Partum Perineal Pain in Episiotomy in Primiparous Women After Instrumental Delivery

An episiotomy is an incision of the perineum to facilitate childbirth by natural means. This gesture is performed in 68% of primiparous women and 31% of multiparous women, according to Audipog data of 2003, with a downward trend since the 80's. The episiotomy reduces the risk of occurrence of anterior perineal tears, but has no preventive effect on 3rd and 4th grade perineal tears, according to the Anglo-Saxon classification. The French national college of obstetricians and gynecologists (CNGOF) recommends thus a restrictive use of episiotomy. Perineal pain are more frequent and intense if the incision of the perineum is important. In particular, simple vaginal or perineal tears are less painful than episiotomies in the first seven days postpartum, whereas at six weeks postpartum, there is no significant difference anymore.The patients are the most symptomatic in the immediate postnatal period, but the pain may persist up to 2 weeks after delivery in 20 to 25% of cases. These pains are often undervalued and may interfere with the mother-child bond in the absence of an effective treatment. Perineal pain are usually treated with painkillers, in particular non-steroidal anti-inflammatory drugs given orally or rectally and paracetamol.

The scar infiltration is one of the components of a multimodal postoperative analgesia strategy. It consists in the simultaneous use of several drugs or analgesic techniques, acting on different pain components in order to improve the overall efficiency. This also reduces the consumption of analgesics having multiple side effects, such as opioids. Local anesthetics act at several levels. First, they block the transmission of pain messages at the nocireceptors level and have an analgesic effect on the nearby surgery site. The immediate post-operative pain is thus diminished. Furthermore, by blocking the pain message at the peripheric level, local anesthetics might have an effect on the formation of central hyperalgesia, responsible for longer-term pain. The local anesthetics also have local and systemic anti-inflammatory properties, that may have an effect on postoperative pain and on the establishment of hyperalgesic phenomena.

The most used local anesthetics at present are bupivacaine, ropivacaine and levobupivacaine. Ropivacaine has a lesser vasodilatory effect than bupivacaine, resulting in longer persistence at the injection point and a blood resorption that is more spread. The systemic toxicity threshold is also higher. Levobupivacaine is the enantiomer of bupivacaine. It has vascular effects, and an intermediate systemic toxicity threshold intermediate between bupivacaine and ropivacaine. Lidocaine has a limited duration of action. Its use is interesting in complement infiltrations when a rapid onset of action is desired.

Many scar infiltration indications are documented in the literature, such as inguinal hernias, hemorrhoids cures, thyroidectomy, orthopedic surgery, breast surgery, and cesarean section.Various studies evaluated the effectiveness of different local anesthetics in episiotomies and perineal tears.

So far, there is no data in the literature regarding the effect of levobupivacaine in episiotomies associated pain. The objective of this study is to evaluate the effect of local injections of levobupivacaine on episiotomies associated pain.