R Mahony, C O’Herlihy, ME Foley
Department of Obstetrics and Gynaecology, University College Dublin, National Maternity Hospital, Holles St, Dublin 2

Abstract
Perineal outcome in 1000 consecutive term non instrumental second vaginal deliveries was correlated with first delivery method and perineal outcome. Our aim was to determine the relationship between perineal outcome at first and second vaginal deliveries. Overall 75% of first non instrumental vaginal deliveries required sutures. Sutures were required at second delivery in 12% (24 of 199) of cases not sutured at first delivery compared with 60.4% (485 of 801) of those sutured. The rate of second perineal repair correlated with method of first delivery and perineal outcome, instrumental delivery – 66.2% (145 of 219), first episiotomy-68.4% (238 of 348) and first sutured tear – 43.6% (102 of 234). The incidence of third /fourth degree tear at first delivery was 1.3% (13/1000) (one recurred at second forceps delivery), compared with 0.6% at second delivery. First delivery outcome should be considered when conducting a second delivery as sixty per cent of women require perineal repair following repair at first delivery.

Introduction
The majority of women sustain some degree of perineal trauma following vaginal delivery.^1,2 For many this is a transient problem but for others, the ensuing consequences such as perineal pain, dyspareunia and anal sphincter dysfunction represent a serious form of postnatal morbidity which can result in long-lasting disability. The degree of trauma and instrumentation sustained during delivery correlates with the severity of perineal morbidity subsequently experienced and it has been shown that up to 40% of women complain of dyspareunia at 3 months following delivery; at six months postpartum, a quarter of all primiparous women report reduced sexual function.³

Episiotomy rates vary widely between institutions and reported episiotomy rates include 62.5% in the USA,⁴ 30% in Europe, while in Argentina,⁵ episiotomy is a routine intervention in nearly all primiparous births. Many factors have been shown to influence perineal outcome including parity, instrumental delivery, epidural analgesia, fetal birth weight, prolonged second stage of labor, ethnicity and fetal position.^6-11 Our aim was to determine the relationship between perineal outcome at first vaginal delivery and second vaginal delivery.

Methods
Details of obstetric outcome including, method of delivery, perineal outcome and birth weight were obtained at second delivery beginning in January 2005 and matched with perineal outcome of first delivery. The study group consisted of women whose second birth was by unassisted vaginal delivery. Women delivered by cesarean section at first or second delivery, or by instrumental delivery at second (but not first) delivery were excluded from the study (Figure 1). First labor was managed according to a standard protocol of active management of labor.¹² Normal vaginal deliveries were conducted by midwives in all cases. All vacuum and forceps deliveries were conducted by the residents or consultant/senior obstetricians. Our institution practices a policy of selective use of episiotomy, indicated at the discretion of the midwife to expedite delivery for delay in the second stage or for fetal distress, or if significant perineal tearing was anticipated. A right medio-lateral episiotomy was always used and repaired in layers, as were all second degree tears, by the senior midwife conducting the delivery with absorbable 2-0 polyglactin sutures; first degree tears – extending through the vaginal mucosa only – were sutured at the discretion of the midwife taking into consideration the extent and vascularity of the tear.

Figure 1 Flow sheet showing the derivation from 1336 consecutive term nulliparas, of the study group of 1000 consecutive non instrumental second vaginal deliveries following first vaginal delivery.

Perineal outcome was categorized as intact, tear not requiring sutures, tear requiring sutures and episiotomy. Third and fourth degree tears were considered together. Labial lacerations were not included in the analysis. Perineal outcome in a second normal vaginal delivery was analyzed according to first perineal outcome and method of first delivery (instrumental or not). The study was deemed exempt by the Ethics Committee of the National Maternity Hospital. Chi Square and Fisher exact test, two tailed, as appropriate were used to analyze data and a p value of<0.05 was considered significant.

Results
Among 1336 term first pregnancies (>37 weeks gestation), 1132 had a vaginal delivery. Of this 1132, 132 second deliveries were cesarean or instrumental, leaving 1000 consecutive term cephalic second unassisted vaginal deliveries for analysis (Figure 1).

Among first deliveries the spontaneous vaginal delivery rate was 78.1% (781 /1000), no sutures were required in 25.5% (197/781), the episiotomy rate was 44.5% (348/781) and overall 74.5% (582/781) required sutures. The instrumental delivery rate was 21.9%/ (219 of 1000) (vacuum 15.4%, forceps 6.5%) and all required sutures. Including first instrumental deliveries, 80.1% (801of 1000) of first deliveries were sutured.

At second delivery no sutures were required in 48.8% (488/1000), the episiotomy rate was 10.2% (102of 1000) and overall 51.2% (512/1000) required sutures. The ratio of episiotomy to sutured tear was 59.8% (348/582) for first and 19.9% (102/512) second deliveries. Method of delivery (instrumental) and need for sutures at first delivery correlated with the need for sutures at second delivery (Table 1). The rate of perineal suturing at second delivery correlated with method of delivery and first perineal outcome (Figure 2) and the relationship was the same even when women who had an elective episiotomy at second delivery. Second infant birth weight was greater than first birth weight in 61.5% (615 of 1000) of cases and compared with a next smaller infant, increased the need for perineal repair (54.7% vs.46.5%; p=0.01). The incidence of third or fourth degree tears at first delivery was 1.3% (13/1000); 12 following normal delivery with a tear and one forceps delivery with an episiotomy; the latter case recurred at second forceps delivery. The incidence at second delivery was 0.6% (6/1000); 6 normal deliveries, 5 with tears and 1 episiotomy and 5 of the 6 had had an episiotomy at first delivery. The ethnicity of the population is stable and 27 of 1000 were non Caucasian.

Figure 2 Perineal outcome at second delivery correlated with method of first delivery and first perineal outcome. (1= 3.724, p=0.053; 2 2=126.22, p<0.001.)

Excluded from the above analysis were 204 women delivered by cesarean section at first delivery of whom 82 had a vaginal birth after cesarean section (VBAC) including 50 non instrumental vaginal deliveries. Among the latter 50 women, 90% required sutures and there was one third degree tear.

Discussion
Most women having a vaginal delivery can anticipate perineal suturing because of perineal trauma sustained during childbirth. Excluding instrumental deliveries, 75% of women require perineal repair following primiparous vaginal delivery and 50% require perineal repair after second vaginal delivery. The need for perineal repair at second delivery is closely related to first outcome; 60%, who require perineal repair after first delivery, require repair following second vaginal delivery. Conversely, only 12% of women with an intact perineum after first delivery require sutures at second vaginal delivery. First vaginal deliveries are characterized by a greater need for perineal repair and numerous studies have shown that serious obstetric trauma including anal sphincter injury is more common following first childbirth.⁷ This may partly be explained by the higher instrumental delivery and accompanying episiotomy rate associated with primiparous delivery. Despite a policy of selective episiotomy, 44% of unassisted primiparous vaginal deliveries were associated with episiotomy and 75% with perineal repair, representing a very large proportion of all primiparous deliveries. Only one in four women experiencing a first unassisted vaginal delivery did not require formal surgical repair.

Not unexpectedly, perineal outcome at second delivery is related to first perineal outcome. A woman can be reassured that if her first delivery was not complicated by the need for perineal repair, then she has almost a 90% chance that she will have either an intact perineum or such minor trauma that she will not need repair at second delivery assuming she does not require instrumental assistance. In addition, the overall episiotomy rate was much lower (10%) at second spontaneous delivery compared with first. Instrumental first delivery might be expected to be a surrogate marker for increased perineal trauma but the perineal outcome at second delivery was similar if first vaginal delivery was associated with episiotomy alone, perhaps indicating that it is episiotomy rather than instrumental delivery that predisposes the perineum to further injury at subsequent vaginal. There was a significantly lower incidence of requirement for perineal repair (43%) at second delivery when first delivery had been complicated by spontaneous laceration which necessitated repair. This does not necessarily make a case for avoiding a first episiotomy as episiotomies were performed in anticipation of a significant tear at first delivery.

The need for suturing at second non instrumental delivery is directly related to the indication for suturing at first delivery in the order first episiotomy (with or without instrumental delivery) (65%) and sutured tear (43%). In anticipation of an increased need for suturing in these cohorts we would encourage the judicious use of a small episiotomy when a tear seems inevitable as pushing against a scarred perineum is painful and distressing and arguably repair of an episiotomy is easier than repair of a scarred perineum that has in effect ruptured. While episiotomy rate varies widely between institutions, there is a general consensus that the rate is too high^13-15, despite the fact that some of the major perceived benefits such as the prevention of obstetric anal sphincter trauma^16,17 and improved healing remain controversial. Whether reducing the episiotomy rate at first delivery would reduce the degree of perineal trauma sustained at both first and second deliveries is unclear.

Although our numbers are small second vaginal delivery after first cesarean section was associated with a high incidence of suturing and has been identified as a risk factor to anal sphincter damage.¹⁸ Finally the issue of perineal repair affects a very large proportion of women having a baby and women frequently ask whether or not they will need sutures following delivery. We believe the data in this study provides valuable information for health care professionals involved in counselling women who are anticipating a vaginal delivery.

References

1. Howden NL, Weber AM, Meyn LA. Episiotomy use among residents and faculty compared with private practitioners. Obstet Gynecol 2004; 103:114-8.
2. Samuelsson E, Ladfors L, Lindblom BG, Hagberg H. A prospective observational study on tears during vaginal delivery: occurrence and risk factors. Acta Obstet Gynecol Scand 2002; 81:44-9.
3. Signorello LB, Harlow BL, Chekos AK, Repke JT. Postpartum sexual functioning and its relationship to perineal trauma: a retrospective cohort study of primiparous women. Am J Obstet Gynecol 2001; 184:881-8.
4. Carrole G, Belizan J. Episiotomy for vaginal birth Cochrane Database Syst Rev.2000:CD000081.
5. Althabe F, Bleizan JM, Bergel E. Episiotomy rates in primiparous women in Latin America: hospital based descriptive study. BMJ 2002; 324:945-6.
6. Robinson JN, Norwitz ER, Cohen AP, Lieberman E. Predictors of episiotomy at first vaginal delivery. Obstet Gynecol 2000;96:214-8.
7. Donnelly VS, Fynes M, Campbell DM, Johnson H, O’Connell PR, O’Herlihy C. Obstetrics events leading to anal sphincter damage. Obstet Gynecol 1998; 92:955-61.
8. Christianson LM, Bovbjerg VE, McDavitt EC, Hullfish KL. Risk factors for perineal injury during delivery. Am J Obstet Gynecol 2003; 189:255-60.
9. Howard D, Davies HD, DeLancey JO, Small Y. Differences in perineal lacerations in black and white primiparous women. Obstet Gynecol. 2000; 96:622-4.
10. van de Bergh JE, Sueters M, Segaar M, van Roosmalen J. Determinants of episiotomy in rural Zimbabwe Acta Obstet Gynecol Scand 2003;82:966-8.
11. Sultan AH, Kamm MA, Hudson CN, Bartram CI. Third degree obstetric anal sphincter tears: risk factors and outcome of primary repair. BMJ 1994; 308:887-91.
12. O’Driscoll K, Meagher D, Robson M. The active management of labor. New York: Mosby Year Book limited; 2004. p.49.
13. Weber AM, Meyn L. Episiotomy use in the United States 1979- 1997.Obstet Gynecol 200; 100:1177-82.
14. Ola ER, Bello O, Abudu OO, Anorlu RI. Episiotomies in Nigeria- should their use be restricted. Niger Postgrad Med J 2002; 9:13-6.
15. Goldberg J, Holtz D, Hyslop T, Tolosa JE. Has the use of routine episiotomy decreased? Examination of episiotomy rates from 1983 to 2000. Obstet Gynecol 2002; 99:395-400.
16. deLeeuw JW, Struijk PC, Vierhout ME, Wallenburg HC. Risk factors for third degree perineal ruptures during delivery. BJOG 2001; 108:383- 7.
17. Bodner-Adler B, Bodner K, Kimberger O, Wagenbichler P, Kaider A, Husslein P et al. Risk factors for third-degree perineal tears in vaginal delivery with an analysis of episiotomy types J Reprod Med 2001;46:752-6.
18. Richter HE, Brumfield CG, Cliver SP, Brugio KL, Neely CL, Varner RE. Risk factors associated with anal sphincter tear: a comparison of primiparous patients, vaginal births after cesarean deliveries and patients with previous vaginal delivery. Am J Obstet Gynecol 2002; 187:1194-8.