Reducing perineal trauma by application of warm packs in the second stage of labor: Histrical controlled trial

Abstract

Objective
The purpose of this study was to clarify whether perineal warm pack application in the second stage of labor reduces first degree and second degree perineal laceration.
Methods
A historical controlled trial design was used. Participants were nulliparous women without medical complications, with delivery being at term, vaginal delivery, singleton pregnancy and cephalic presentation. The intervention method involved the midwife applying a warm moist towel to the perineum from close to full cervical dilation until vulvar cleaning is conducted. The towel was exchanged every 30 minutes to maintain its temperature. The extent of perineal laceration was evaluated immediately after delivery by the obstetrician attending the delivery. At the same time, the woman's basic information was collected from the medical record. Data analysis included t test and chi-square test. This study was approved by the institutional review board.
Results
Participants comprised 49 women in the intervention group and 50 women in the control group. There was no significant difference between participant characteristics of the 2 groups. In the intervention group, first degree perineal laceration occurred for 28 women (57.1%), and second degree perineal laceration occurred for 16 women(32.7%). In the control group, first degree perineal laceration occurred for 31 women (62.0%), and second degree perineal laceration occurred for 13 women (26.0%), with no significant difference between the 2 groups (p=0.517). Third degree perineal laceration occurred for 3 women in the intervention group (6.1%), and for 3 women in the control group (6.0%), while fourth degree perineal laceration did not occur in either group. Warm pack application time was a mean of 2.77±2.43 hours for the intervention group. Concerning warm pack application time and perineal laceration, warm pack application time for first degree perineal laceration was a mean of 2.27±2.59 hours, for second degree perineal laceration it was a mean of 3.98±1.99 hours, and for third degree perineal laceration it was a mean of 1.85±1.51 hours, with significant difference (p=0.002). No significant correlation was found between haemorrhage volume and warm pack application time, and between haemorrhage volume and the duration from warm pack application start until delivery of the baby. An increase in bleeding volume due to warming of the perineum was not found.
Conclusions
The effect of reduction of first degree and second degree perineal laceration due to warm pack application during labor was not found. However, warm pack application has the merits of physiologically improving skin elasticity, increasing circulatory blood flow, and producing heat shock proteins which are said to promote recovery, so a positive effect can be expected. Further research into the timing and application method is needed.