The use of local anesthesia in repairing the perineal trauma from spontaneous delivery: a comparative study on the effectiveness of the anesthetic solution with and without vasoconstrictors

The perineal trauma, caused by episiotomy or ruptures, is quite frequent during the spontaneous delivery, being the local anesthesia widely utilized when repairing lesions in the vulvo-perineal region. Throughout the specialized literature, scarce are the studies on the most suitable anesthetic solutions for this kind of anesthesia. Even though there are recommendations for the adoption of the anesthetic with vasoconstrictor, because of the prolonged permanence of the anesthetic solution in the region, thus ensuring a bigger time of action, and because of the reduction in the plasmatic concentration of the drug, its utilization in practice is restricted. The goal of the study was to compare the necessary quantity of anesthetic to inhibit pain during the suture of the perineal trauma in women with an episiotomy or with first or second degree spontaneous lacerations, according to the use or not of vasoconstrictor in the anesthetic solution. This is a randomized and controlled research, with double blind trial, performed in the Birth Centre at Amparo Maternal, in the city of Sao Paulo. There were 96 parturients included in the study and then divided into three blocks: first degree laceration, second degree laceration and episiotomy. In each block, constituted of 32 women, 16 women were administered the anesthetic solution with vasoconstrictor and 16 with no vasoconstrictor. Results show that in the first degree laceration block the average of anesthetic with vasoconstrictor presented a statistically significant difference (p=0,002), with 1,0 ml (C.I. -1,6; -0,4) less than the average of the anesthetic without vasoconstrictor; in 95% of the cases, 1 to 2 ml of the solution with vasoconstrictor was utilized, while in 87,5% of the cases, the anesthetic without vasoconstrictor varied from 2 to 4 ml. In the second degree laceration block, the average of anesthetic solution with vasoconstrictor was 3,7 ml (C.I. -5,8; -1,6) less than the average of the anesthetic without vasoconstrictor, being statistically significant (p=0,001); in 87,5% of the cases, the maximum quantity of anesthetic with vasoconstrictor administered was 6 ml, while in 81,3% of the cases, women who were given the anesthetic without vasoconstrictor, received 7 ml or more. Considering the extent of the laceration, the size of the episiotomy practiced on the women of the study was adopted as a parameter to classify the extent of the laceration. The lacerations of a smaller extent were grouped as small-sized, the ones in which the size was similar to the size of the episiotomy were grouped as medium-sized, and as large-sized the ones that oversized the episiotomy. For the episiotomy, the average of anesthetic with vasoconstrictor was 0,3 ml (C.I. -2,1; 1,5) less than the average of the anesthetic without vasoconstrictor, with no statistic significance (p=0,724). Results allow us to confirm the hypothesis that the utilization of the anesthetic with vasoconstrictor in the local anesthesia during the suture of the perineal lacerations in the spontaneous delivery increases the effectiveness of the local anesthesia. Although the volume of anesthetic utilized in the suture of the first and second degree lacerations is significantly reduced by the association with vasoconstrictor, the clinical relevance of this result must be taken into further consideration.