Journal of Obstetrics and Gynaecology
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Trends in obstetric anal sphincter injuries over 10 years V. Tyagi, M. Perera & K. Guerrero To cite this article: V. Tyagi, M. Perera & K. Guerrero (2013) Trends in obstetric anal sphincter injuries over 10 years, Journal of Obstetrics and Gynaecology, 33:8, 844-849 To link to this article: http://dx.doi.org/10.3109/01443615.2013.831045
Published online: 12 Nov 2013.
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Journal of Obstetrics and Gynaecology, November 2013; 33: 844–849 © 2013 Informa UK, Ltd. ISSN 0144-3615 print/ISSN 1364-6893 online DOI: 10.3109/01443615.2013.831045
OBSTETRICS
Trends in obstetric anal sphincter injuries over 10 years V. Tyagi, M. Perera & K. Guerrero
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Department of Urogynaecology, NHS Greater Glasgow and Clyde, Glasgow
Obstetric anal sphincter injuries (OASIS) is a known complication of vaginal delivery and has significant public health issues, as it can cause both short- and long-term morbidity in women. The most commonly reported complications include different grades of faecal/flatus incontinence, pain and sexual dysfunction. In our study, we found a rising trend in OASIS rates in vaginal deliveries, with the rising rate of forceps and the falling rate of SVD, which is at least partly due to increased awareness and training in OASIS. However, there is an actual increase in the number of such tears at vaginal deliveries. Midwifery and obstetric practices have certainly changed over the last decade and we discuss the possible factors, which might be contributing to such a rise.
All deliveries in the unit are recorded in the hospital database (PROTOS). Details about labour and delivery are entered by the delivering midwife. We identified all the patients who were recorded as sustaining an OASIS in our unit, from January 2000 to December 2010. We were able to calculate delivery rates and look into some risk factors thought to be associated with OASIS, which were recorded on this database. Yearly analysis of the data was performed; SPSS 20 was used for statistical analysis. The χ2-test for trend using regression analysis was used to calculate the p value.
Keywords: Anal sphincter tear, incidence, obstetric perineal injury, outcome, risk factors
Birth rates
Introduction Obstetric anal sphincter injuries (OASIS) is a serious and common complication of vaginal delivery (McCandlish et al. 1998; Pirhonen et al. 1998; Samuelson et al. 2000; Parnell et al. 2001). The reported incidence of OASIS varies between 0.5% and 2.5% of vaginal deliveries (Walsh et al. 1996; BorelloFrance et al. 2006; Andrew et al. 2007). Risk factors for OASIS have been identified in a number of retrospective studies, namely birth weight over 4 kg (up to 2%); nulliparity (up to 4%); induction of labour (up to 2%); epidural analgesia (up to 2%); second stage longer than 1 h (up to 4%); shoulder dystocia (up to 4%); midline episiotomy (up to 3%); forceps delivery (up to 7%) (De Leeuw et al. 2001). Over last 10 years, obstetric and midwifery practice in the UK has changed. There is an increase in the incidence of medical interventions as routine procedures in normal birth, with the falling number of midwives In addition, the characteristics of women giving birth have changed. Both newborn babies and mothers are heavier and the use of epidural analgesia has increased. There has also been a rise in caesarean section rates (Thomas and Paranjothy 2001; Brick and Layte 2009). Our aim was to look at the trends in OASIS incidence and the risk factors over the last 10 years in our unit.
Methods The setting is a large teaching hospital with an obstetric unit that also functions as a regional tertiary unit for obstetrics and neonatology.
Results The number of births has increased steadily in the last decade (Figure 1) from 4,649 in 2001 to 6,387 in 2010. There has been a decline in the percentage of vaginal deliveries with an associated rise in the rate of caesarean section over the last 10 years (Figure 2). The proportion of women having spontaneous vaginal deliveries (SVD) overall has declined (60% in 2001 to 54% in 2010). There has been a decline in rate of ventouse delivery (6.6% in 2001 to 3.3% in 2010). The rate of forceps delivery has increased from 7.7% in 2001 to 9.4% in 2010 (Figure 3).
OASIS rates The incidence (% of OASIS) is calculated as the number of reported anal sphincter injuries divided by the total number of vaginal births, i.e. SVD and instrumental deliveries (OASIS rate ⫽ no. of OASIS/no. of vaginal births ⫻ 100). Apart from a dip in 2008, we found an overall yearly increase in the percentage of women sustaining OASIS over the last 10 years (Figure 4). Our OASIS rate has increased from 1.3% (n ⫽ 44) in 2001 to 4.16% (n ⫽ 177) in 2010 (p ⫽ 0.001, χ2-test for trend). This is significant both statistically and clinically. The rate of 4th degree tears has been variable over the last 10 years; 13.63% (n ⫽ 4) in 2001 to 2.2% (n ⫽ 4) in 2010 (Figure 5). The majority of patients who sustained an OASIS had an SVD, with gradual increase in the percentage of SVDs contributing to a total cohort from 56% of all OASIS patients in 2002 to 66% in 2010 (Figure 6). Forceps delivery was the second most common mode of delivery in our OASIS patients, with a rise in the percentage of the OASIS population from 27.27% in 2001 to 36% in 2010. Ventouse delivery was the least common mode of delivery in women with OASIS. Looking at the incidence of OASIS in different modes of vaginal delivery (no. of OASIS/total number of women having
Correspondence: V. Tyagi, Department of Obstetrics and Gynaecology, Southern General Hospital, 1345 Govan Road, Glasgow G51 4TF. E-mail address: [email protected]
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The total numbers of primiparous women delivering (both vaginal delivery and caesarean section) have increased from 1,857 in 2001 to 3,182 in 2010 (Figure 7). The percentage of primiparous women having vaginal delivery (SVD, forceps and ventouse) has fallen from 73.92% in 2001 to 66.15% in 2010. The percentage of primiparous women who had vaginal delivery and sustained OASIS has increased from 1.2% in 2001 to 6.5% in 2010, with a drop in 2008, which corresponds to a drop in the rate of forceps delivery and OASIS in that year (Figure 8). In the group of women who sustained OASIS, the percentage of women who were primiparous has increased over the last decade; number of primiparous women with OASIS/total number of primiparous women delivered vaginally (Figure 9).
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In women who had forceps delivery in 2001, only 3.4% sustained an OASIS compared with an alarming 10.5% in 2010. Therefore, the OASIS rate with all SVD, forceps and ventouse has increased by more than three times (Figure 7). The dip in OASIS rate in 2008 corresponds with the decrease in incidence of OASIS with instrumental deliveries that year. The P value using regression of prevalence is ⬍ 0.001 for SVDs and 0.004 for forceps. The P value for ventouse OASIS rate was not calculated, as the numbers were too small. The rise in the incidence of OASIS with SVD and forceps delivery in last 10 years is therefore both clinically and statistically significant.
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Figure 4. Incidence of OASIS.
that particular mode of delivery), there has been a significant rise in the incidence of OASIS in patients with SVD, from 1.0% in 2001 to 3.14% in 2010. Though the number of ventouse deliveries has fallen overall in the last 10 years, the percentage of women who sustained OASIS with ventouse delivery increased from 0.6% in 2001 to 2.65% in 2010.
We looked at various risk factors in the group of women with OASIS; number of women with OASIS and associated risk factor/total number of women with OASIS in that particular year (Figure 10). Rate of episiotomy with or without instrumental delivery over 10 years was variable, between 34% and 47%. There appeared to be no association with the OASIS rates. The percentage of babies with birth weight ⬎ 4 kg in this group has remained fairly static, with a small drop in year 2002–2004. The percentage of women who had shoulder dystocia and OASIS had increased from 0% in 2001 to 5.0% in 2010. The percentage of women who had OASIS and were induced, has declined from 44% in 2001 to 31% in 2010 There has also been a fall in the percentage of women who sustained OASIS and had a prolonged second stage of labour (⬎ 1 h) (72% in 2001 to 61% 2010). There is a downward trend in the percentage of women
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who sustained OASIS and had received epidural analgesia in labour (53% in 2001 and 33.89% in 2010). We are unable to calculate the risk of sustaining OASIS with these risks factors, as data for the entire population was not available to us.
Interpretation of results There has been an increase in the total number of births in the last 10 years, with a fall in the number of vaginal deliveries. The forceps rate has increased with a decrease in the ventouse rate. There has been steady increase in the rate of OASIS over the last 10 years. We have identified a three-fold increase in rate of OASIS in SVD and forceps, and a four-fold increase with ventouse delivery. The percentage of primiparous women sustaining OASIS has increased.
Discussion The reported incidence of OASIS varies from 0.5% to 6% of all vaginal deliveries in centres where mediolateral episiotomies are practised (Sultan et al. 1994; Walsh et al. 1996; Tetzschner et al. 1996; Zetterstrom et al. 1999; Fitzpatrick et al. 2000; De Leeuw et al. 2001; Jander and Lyrenas 2001). We have seen a significant rise in the rate of OASIS in the last decade in both instrumental and non-instrumental deliveries, with the overall incidence of OASIS of 4.3% in 2010, which is in-line with the published literature. In a national population-based study in Sweden, the incidence of 3rd degree tears was reported to have increased by over 60%, from 1994 to 2004 (Ekeus et al. 2008). Another retrospective crosssectional study in Norwich, UK in 2009, reported the frequency
of anal sphincter tears of 3.2%, with the increase in incidence between 2005 and 2007 (Revicky et al. 2010). Laine et al. (2009), compared the incidence of OASIS in four Nordic countries and found a similar rising trend in the incidence of OASIS (Sweden 0.5% in 1973 to 4.2% in 2004; Norway 1.6% in 1968 to 4.1% in 2004 and Finland 0.1% in 1986 to 0.6% in 2004). The overall birth rates have increased but the rate of SVD is falling and this may reflect increasing incidence of caesarean section. Despite the falling SVD rate, the percentage of women who had SVD and OASIS has increased. In the UK, the Royal College of Obstetricians and Gynaecologists has produced clinical guidelines in recognition of the wide variation in forceps rates between hospitals, and a desire to reduce morbidity through training (Thomas and Paranjothy 2001). The rates of instrumental vaginal delivery range between 10% and 15% (Johanson 2000). These have remained fairly constant, although there has been a change in preference of instrument. In the 1980s, most instrumental vaginal deliveries were by forceps, but by 2000 this had decreased to under a half. Much of the decline has been attributed to an increasing preference for vacuum extraction or for caesarean section when complex vaginal delivery is anticipated (Bofill et al. 1996; Towner et al. 1999). This trend is seen clearly in England, with the rate of forceps delivery being 5.5% and ventouse delivery rate of 6.6% in 2009. However, in Scotland, the rate of forceps delivery has increased from 6.8% in 2001 to 9.7% in 2010, whereas vacuum delivery has declined from 5.6% in 2001 to 2.9% in 2010 (Birth in Scottish Hospitals 2009/2010). We found that in-keeping with Scottish data, in our institution, the rate of forceps delivery increased and rate of ventouse delivery declined over the last 10 years.
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Figure 6. Different modes of vaginal delivery in women with OASIS.
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We also found higher rate of OASIS with forceps delivery than with ventouse delivery. This is consistent with the finding that forceps delivery carries greater risk than ventouse delivery in causing OASIS (Fitzpatrick et al. 2000; Laine et al. 2009). A recent Cochrane review concluded that with forceps, there is significantly increased risk of 3rd and 4th degree perineal tears (with or without episiotomy) (O’Mahony et al. 2010). This is most likely due to the increased diameter of the fetal head with forceps delivery; a finding that also agrees with the published literature. The increase in the rate of forceps delivery might explain the increase in the number of OASIS associated with forceps but there has been a rise in the percentage of women who had forceps delivery and OASIS. There was a fall in the incidence of OASIS in 2008, which corresponds to the decline in the rate of OASIS in women who had forceps and ventouse assisted delivery in that year but the rate of forceps delivery followed an upward trend. In our institution, although the number of ventouse deliveries has decreased and the percentage of women who sustained OASIS due to ventouse delivery has decreased, the actual respective rate of OASIS with ventouse delivery has increased. This raises the question of whether it is due to increased awareness and recognition of such tears or due to other factors such as technique of delivery or role of episiotomy in causing such tears (Groom and Paterson-Brown 2002). Handa et al. (2001) were able to prove that the clinical diagnosis of OASIS improved by increased vigilance. In our institution, we have also noticed increased incidence of OASIS since 2003/2004, when the OASIS training course in perineal anatomy and recognition of severe perineal trauma was started. However, the incidences have increased since then and have still not plateaued, which we would expect if it was simply recognition increasing the incidence. Therefore, we think that the rising trend in OASIS cannot be explained only by increased awareness and recognition of such tears. Changing practices towards the second stage of labour could have influenced the higher proportion of OASIS. Various studies have reported contradictory findings on whether episiotomy is related to an increased risk of OASIS. Systematic reviews of RCT and some earlier studies (Argentine Incidence of OASIS
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Figure 8. Percentage of primiparous women delivered in last 10 years.
Episiotomy Trial Collaborative Group 1993; Walsh et al. 1996; Carroli and Belizan 2000; Yousef et al. 2005; Dandolu et al. 2005; Andrew et al. 2006; Mikolajczyk et al. 2008; Alperin et al. 2008; Murphy et al. 2009) suggest that mediolateral episiotomy was associated with an increased risk of OASIS or there was statistically no significant difference in the rate of OASIS. De Leeuw et al. (2001) showed a protective effect of episiotomy in their study. A study by Revicky et al. (2010) showed mediolateral episiotomy was associated with lower incidence of OASIS. However, the method and technique of mediolateral episiotomy should be considered. A study by Andrews et al. (2005) investigated potential differences in the cutting of mediolateral episiotomy between doctors and midwives. No midwife and only 13 (22%) doctors performed truly mediolateral episiotomies. It appears that the majority of episiotomies are not truly mediolateral but closer to the midline. More focussed training in the mediolateral episiotomy technique is recommended. Vertex vaginal delivery with no mediolateral episiotomy has a 1.4 times higher risk of sustaining OASIS than those with it (Revicky et al. 2010). Ekeus et al. (2008) found mediolateral episiotomy to be related to an increase in incidence of OASIS with SVD but protective for instrumental deliveries. In our study, the percentage of women who sustained OASIS and had episiotomy was variable and all women who had instrumental delivery were documented as having mediolateral episiotomies. Again the data for the entire population could not be obtained and therefore we cannot compare the rate of OASIS with and without episiotomy. The result of case–controlled study (Eogan et al. 2006) revealed that a smaller angle of episiotomy is more likely to lead to OASIS. They calculated a 50% relative reduction in the risk of OASIS for every 6.3% increment in the angle of episiotomy. Lateral episiotomy by indication is the method used in Finland, where the frequency of OASIS is lowest among the four Nordic countries (Laine et al. 2009). This leads to the suggestion of better training of obstetric and midwifery staff in the better routines of episiotomy techniques and may be trending towards lateral episiotomy to gain better results. In our study population, we did not find any increase in the rate of association of various risk factors in the group of women who sustained OASIS, apart from the rising incidence of primiparous women sustaining OASIS. However, as the data are collected retrospectively, we were unable to calculate the relative risk of sustaining OASIS with different risks factors. Primiparity is one of the most important risk factors, since primiparous women have a 10-fold increase risk of OASIS (Moller Bek and Laurberg 1992; De Leeuw et al. 2001; Eogan et al. 2006). During the past decade, there have been major changes in both obstetric and midwifery practice in UK. Both newborn babies and mothers are getter bigger; mums are getting older and the use of epidural analgesia is increasing. At the same time, the rate of caesarean section has increased (Thomas and Paranjothy 2001).
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Figure 10. Trend of various risk factors in women with OASIS.
Manual perineal protection is little investigated. The method of protecting the perineum when the baby’s head is delivering is described in old books for midwives but not in the new books (Johanson and Menon 2000)! This might signal that perineal protection might not be considered as a routine part of modern obstetrics and midwifery practice. Also, alternative birth positions have become more common and visualising of the perineum has become more difficult or is considered unnecessary. There may be a tendency not to guard the perineum (hands-off approach) during the delivery of the head. One of the possible reasons can be as a result of the HOOP trial (Murphy et al. 2009). Although the primary outcome was to asses pain after 10 days of delivery, it is often taken as evidence to disregard perineal support during delivery of the head (de Souza Caroci da costa and Gonzalez Riesco 2006). Various studies have shown manual protection of the perineum to be protective against OASIS. In an international trial in Norway (Laine et al. 2008) by teaching and doing the classic method of delivering the fetal head, the incidence of OASIS decreased from 4.03% to 1.17%. Hirsch et al. (2008) managed to reduce the incidence of lacerations from 42% to 26% by changing clinical recommendations through departmental lectures, distributing articles and manuals and training physicians. Trochez et al. (2011) in an observational postal questionnaire found that midwives prefer the ‘hands-off ’ method. Lessexperienced midwives were more likely to prefer the ‘hands-off ’ and a higher proportion of midwives in the ‘hands-off ’ group would never do an episiotomy. This may be because of the perceived lack of clinical need for episiotomies, but is also likely to be due to experience and confidence in performing episiotomies. We were unable to obtain data on whether perineal protection/ hands-on technique was used in our population, due to the retrospective nature of the study and this data was not recorded in the system.
Conclusion We conclude that the incidence of OASIS has increased in our institution over the last decade. The rate of forceps delivery had increased and the SVD rate is falling. The rise in OASIS is seen in both SVD and instrumental deliveries. However, there has been no significant increase in the incidence of many of the associated risks factors with OASIS. The rise in OASIS can be partly explained due to increased awareness and recognition of such tears. However, the change in practices (episiotomy/perineal support) may be contributing factors.
Acknowledgement We would like to thank all those who have helped with the collection of the data and Mr David Young, statistician at the Strathclyde University, for statistical advice. Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
References Alperin M, Krohn MA, Parvianien K. 2008. Episiotomy and increase in the risk of obstetric laceration in subsequent vaginal delivery. Obstetrics and Gynecology 111:1274–1278. Andrew V, Sultan AH, Thakar R, Jones PW. 2006. Risk factors for obstetrics anal sphincter injury: a prospective study. Birth 33:117–122. Andrew V, Thakar R, Sultan AH, Jones PW. 2007. Evaluation of postpartum perineal pain and dyspareunia – a prospective study. European Journal of Obstetrics, Gynecology, and Reproductive Biology 137:152–156. Andrews V, Thakar R, Sultan AH, Jones PW. 2005. Are mediolateral episiotomies actually mediolateral? British Journal of Obstetrics and Gynaecology 112:1156–1158. Argentine Episiotomy Trial Collaborative Group. 1993. Routine versus selective episiotomy: a randomised controlled trial. Lancet 342:1517–1518. Bofill JA, Rust OA, Perry KG, Roberts WE, Martin RW, Morrison JC. 1996. Operative vaginal delivery: a survey of fellows of ACOG. Obstetrics and Gynecology 88:1007–1010. Borello-France D, Burgio KL, Richter HE, Zyczynski H, Fitzpatrick Fitzgerald MP et al. 2006. Fecal and urinary incontinence in primiparous women. Obstetrics and Gynecology 108:863–872. Brick A, Layte R. 2009. ESRI working paper 309. Recent trends in the caesarean section rate in Ireland 1999–2006. Dublin: The Economic and Social Research Institute. Carroli G, Belizan J. Episiotomy for vaginal birth. 2000. Cochrane Database of Systematic Reviews (2):CD000081. Dandolu V, Chatwani A, Harmanli O, Floro C, Gaughan JP, Hernandex E. 2005. Risk factors for obstetric anal sphincter injury. International Urogynecology Journal and Pelvic Floor Dysfunction 16:304–307. De Leeuw JW, Strujik PC, Vierhout ME, Wallenburg HC. 2001. Risk factors for third degree perineal ruptures during delivery. British Journal of Obstetrics and Gynaecology 108:383–387. de Souza Caroci da costa A, Gonzalez Riesco ML. 2006. A comparison of hands off and hands on technique for decreasing perineal laceration at birth. Journal of Midwifery and Women’s Health 51:106–111. Ekeus C, Nilsson E, Gottvall K. 2008. Increasing incidence of anal sphincter tears among primiparous in Sweden: A population based register study. Acta Obstetricia et Gynecologica Scandinavica 87:564–573. Eogan M, Daly L, O’Connell PR, O’Herlihy C. 2006. Does the angle of episiotomy affect the incidence of anal sphincter injury? British Journal of Obstetrics and Gynaecology 113:190–194. Fitzpatrick M, Fynes M, Cassidy M, Behan M, O’Connell PR, O’Herlihy C. 2000. Prospective study of the influence of parity and operative technique on the outcome of primary anal sphincter repair following obstetric injury. European Journal of Obstetrics, Gynecology, and Reproductive Biology 89:159–163.
Downloaded by [York University Libraries] at 04:48 07 November 2015
Current trend in obstetric anal sphincter injuries 849 Groom KM, Paterson-Brown S. 2002. Can we improve the diagnosis of third degree tears? European Journal of Obstetrics, Gynecology, and Reproductive Biology 101:19–21. Handa VL, Danielsen BH, Gilbert VM. 2001. Obstetric anal sphincter lacerations. Obstetrics and Gynecology 98:225–230. Hirsch E, Haney EI, Gordon TE, Silver RK. 2008. Reducing higher order perineal laceration during operative delivery. American Journal of Obstetrics and Gynecology 198:668.e1–e5. Jander C, Lyrenas S. 2001. Third and fourth degree perineal tears: predictor factors in referral hospital. Acta Obstetricia et Gynecologica Scandinavica 80:229–234. Johanson RB, Menon BK. 2000. Vacuum extraction vs forceps for assisted vaginal delivery. Cochrane Database of Systematic Reviews (3): CD000224. Johanson RB. 2000. Instrumental vaginal delivery. London: Royal College of Obstetricians and Gynaecologists. Laine K, Gissler M, Pirhonen J. 2009. Changing incidence of anal sphincter injuries in four Nordic countries through the last decades. European Journal of Obstetrics, Gynecology, and Reproductive Biology 146:71–75. Laine K, Pirhonen T, Rolland R, Pirhonen J. 2008. Decreasing the trend of anal sphincter tears during delivery. Obstetrics and Gynecology 111:1053–1057. McCandlish R, Bowler U, van Asten H, Berridge G, Winter C, Sames L et al. 1998. A randomised controlled trial of care of the perineum during second stage of labour. British Journal of Obstetrics and Gynaecology 105:1262–1272. Mikolajczyk RT, Zhang J, Troendle J, Chan L. 2008. Risk factor for birth canal lacerations in primiparous women. American Journal of Perinatology 25:259–264. Moller Bek K, Laurberg S. 1992. Intervention during labour: Risk factor associated with complete tear of anal sphincter. Acta Obstetricia et Gynecologica Scandinavica 71:520–524. Murphy DJ, McLeod M, Bahl R, Goyder K, Howarth L, Strachan B. 2009. A randomised controlled trial of routine vs. restrictive use of episiotomy at operative vaginal delivery: a multicentre pilot study. Obstetrical and Gynecological Survey 64:220–221. O’Mahony F, Hofmeyr GJ, Menon V. 2010. Choice of instruments for assisted vaginal delivery. Cochrane Database of Systematic Reviews (11):CD005455.
Parnell C, Langhoff-Roos J, Moller H. 2001. Conduct of labour and rupture of sphincter Ani. Acta Obstetricia et Gynecologica Scandinavica 80: 356–361. Pirhonen JP, Gernman SE, Haadem K et al. 1998. Frequency of anal sphincter rupture at delivery in Sweden and Finland- result of difference in manual help to the baby’s head. Acta Obstetricia et Gynecologica Scandinavica 77:974–977. Revicky V, Nirmal D, Mukhopadhyay S, Morris EP, Nieto JJ. 2010. Could a mediolateral episiotomy prevent obstetric anal sphincter injury? European Journal of Obstetrics and Gynecology and Reproductive Biology 150:142–146. Samuelson E, Ladfors L, Wennerholm UB, Gareberg B, Nyberg K, Hegeberg H. 2000. Anal sphincter tear: prospective study of obstetrics risk factors. British Journal of Obstetrics and Gynaecology 107:926–931. Sultan AH, Kamm MA, Hudson CN, Bartram CI. 1994. Third degree obstetric anal sphincter tears: risk factors and outcome of primary repairs. British Medical Journal 308:887–891. Tetzschner T, Sorenson M, Lose G, Christiansen J. 1996. Anal and urinary incontinence in women with obstetric anal sphincter rupture. British Journal of Obstetrics and Gynaecology 103:1034–1040. Thomas J, Paranjothy S. 2001. National sentinel caesarean section audit report. London: Royal College of Obstetricians and Gynaecologists Clinical Effectiveness Support Unit. Towner D, Castro MA, Eby-Wilkens E, Gilbert WM. 1999. Effect of mode of delivery in nulliparous women on neonatal intracranial injury. New England Journal of Medicine 341:1709–1714. Trochez R, Waterfield M, Freeman RM. 2011. Hands on or hands off the perineum: a survey of care of the perineum in labour (HOOPS). International Urogynecology Journal 22:1279–1285. Walsh CJ, Mooney EF, Upton GJ, Motson RW. 1996. Incidence of third degree tear in labour and outcome after primary repair. British Journal of Surgery 83:218–221. Yousef R, Ramalingam U, Macleod M, Murphy DJ. 2005. Cohort study of maternal and fetal morbidity in relation to use of episiotomy at instrumental vaginal delivery. British Journal of Obstetrics and Gynaecology 112:941–945. Zetterstrom J, Lopez A, Anzen B, Norman M, Holmstrom B, Mellgran A 1999. Anal sphincter tear at vaginal delivery: risk factors and clinical outcomes of primary repair. Obstetrics and Gynecology 94:21–28.
ISSN: 0144-3615 (Print) 1364-6893 (Online) Journal homepage: http://www.tandfonline.com/loi/ijog20
Trends in obstetric anal sphincter injuries over 10 years V. Tyagi, M. Perera & K. Guerrero To cite this article: V. Tyagi, M. Perera & K. Guerrero (2013) Trends in obstetric anal sphincter injuries over 10 years, Journal of Obstetrics and Gynaecology, 33:8, 844-849 To link to this article: http://dx.doi.org/10.3109/01443615.2013.831045
Published online: 12 Nov 2013.
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Date: 07 November 2015, At: 04:48
Journal of Obstetrics and Gynaecology, November 2013; 33: 844–849 © 2013 Informa UK, Ltd. ISSN 0144-3615 print/ISSN 1364-6893 online DOI: 10.3109/01443615.2013.831045
OBSTETRICS
Trends in obstetric anal sphincter injuries over 10 years V. Tyagi, M. Perera & K. Guerrero
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Department of Urogynaecology, NHS Greater Glasgow and Clyde, Glasgow
Obstetric anal sphincter injuries (OASIS) is a known complication of vaginal delivery and has significant public health issues, as it can cause both short- and long-term morbidity in women. The most commonly reported complications include different grades of faecal/flatus incontinence, pain and sexual dysfunction. In our study, we found a rising trend in OASIS rates in vaginal deliveries, with the rising rate of forceps and the falling rate of SVD, which is at least partly due to increased awareness and training in OASIS. However, there is an actual increase in the number of such tears at vaginal deliveries. Midwifery and obstetric practices have certainly changed over the last decade and we discuss the possible factors, which might be contributing to such a rise.
All deliveries in the unit are recorded in the hospital database (PROTOS). Details about labour and delivery are entered by the delivering midwife. We identified all the patients who were recorded as sustaining an OASIS in our unit, from January 2000 to December 2010. We were able to calculate delivery rates and look into some risk factors thought to be associated with OASIS, which were recorded on this database. Yearly analysis of the data was performed; SPSS 20 was used for statistical analysis. The χ2-test for trend using regression analysis was used to calculate the p value.
Keywords: Anal sphincter tear, incidence, obstetric perineal injury, outcome, risk factors
Birth rates
Introduction Obstetric anal sphincter injuries (OASIS) is a serious and common complication of vaginal delivery (McCandlish et al. 1998; Pirhonen et al. 1998; Samuelson et al. 2000; Parnell et al. 2001). The reported incidence of OASIS varies between 0.5% and 2.5% of vaginal deliveries (Walsh et al. 1996; BorelloFrance et al. 2006; Andrew et al. 2007). Risk factors for OASIS have been identified in a number of retrospective studies, namely birth weight over 4 kg (up to 2%); nulliparity (up to 4%); induction of labour (up to 2%); epidural analgesia (up to 2%); second stage longer than 1 h (up to 4%); shoulder dystocia (up to 4%); midline episiotomy (up to 3%); forceps delivery (up to 7%) (De Leeuw et al. 2001). Over last 10 years, obstetric and midwifery practice in the UK has changed. There is an increase in the incidence of medical interventions as routine procedures in normal birth, with the falling number of midwives In addition, the characteristics of women giving birth have changed. Both newborn babies and mothers are heavier and the use of epidural analgesia has increased. There has also been a rise in caesarean section rates (Thomas and Paranjothy 2001; Brick and Layte 2009). Our aim was to look at the trends in OASIS incidence and the risk factors over the last 10 years in our unit.
Methods The setting is a large teaching hospital with an obstetric unit that also functions as a regional tertiary unit for obstetrics and neonatology.
Results The number of births has increased steadily in the last decade (Figure 1) from 4,649 in 2001 to 6,387 in 2010. There has been a decline in the percentage of vaginal deliveries with an associated rise in the rate of caesarean section over the last 10 years (Figure 2). The proportion of women having spontaneous vaginal deliveries (SVD) overall has declined (60% in 2001 to 54% in 2010). There has been a decline in rate of ventouse delivery (6.6% in 2001 to 3.3% in 2010). The rate of forceps delivery has increased from 7.7% in 2001 to 9.4% in 2010 (Figure 3).
OASIS rates The incidence (% of OASIS) is calculated as the number of reported anal sphincter injuries divided by the total number of vaginal births, i.e. SVD and instrumental deliveries (OASIS rate ⫽ no. of OASIS/no. of vaginal births ⫻ 100). Apart from a dip in 2008, we found an overall yearly increase in the percentage of women sustaining OASIS over the last 10 years (Figure 4). Our OASIS rate has increased from 1.3% (n ⫽ 44) in 2001 to 4.16% (n ⫽ 177) in 2010 (p ⫽ 0.001, χ2-test for trend). This is significant both statistically and clinically. The rate of 4th degree tears has been variable over the last 10 years; 13.63% (n ⫽ 4) in 2001 to 2.2% (n ⫽ 4) in 2010 (Figure 5). The majority of patients who sustained an OASIS had an SVD, with gradual increase in the percentage of SVDs contributing to a total cohort from 56% of all OASIS patients in 2002 to 66% in 2010 (Figure 6). Forceps delivery was the second most common mode of delivery in our OASIS patients, with a rise in the percentage of the OASIS population from 27.27% in 2001 to 36% in 2010. Ventouse delivery was the least common mode of delivery in women with OASIS. Looking at the incidence of OASIS in different modes of vaginal delivery (no. of OASIS/total number of women having
Correspondence: V. Tyagi, Department of Obstetrics and Gynaecology, Southern General Hospital, 1345 Govan Road, Glasgow G51 4TF. E-mail address: [email protected]
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The total numbers of primiparous women delivering (both vaginal delivery and caesarean section) have increased from 1,857 in 2001 to 3,182 in 2010 (Figure 7). The percentage of primiparous women having vaginal delivery (SVD, forceps and ventouse) has fallen from 73.92% in 2001 to 66.15% in 2010. The percentage of primiparous women who had vaginal delivery and sustained OASIS has increased from 1.2% in 2001 to 6.5% in 2010, with a drop in 2008, which corresponds to a drop in the rate of forceps delivery and OASIS in that year (Figure 8). In the group of women who sustained OASIS, the percentage of women who were primiparous has increased over the last decade; number of primiparous women with OASIS/total number of primiparous women delivered vaginally (Figure 9).
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In women who had forceps delivery in 2001, only 3.4% sustained an OASIS compared with an alarming 10.5% in 2010. Therefore, the OASIS rate with all SVD, forceps and ventouse has increased by more than three times (Figure 7). The dip in OASIS rate in 2008 corresponds with the decrease in incidence of OASIS with instrumental deliveries that year. The P value using regression of prevalence is ⬍ 0.001 for SVDs and 0.004 for forceps. The P value for ventouse OASIS rate was not calculated, as the numbers were too small. The rise in the incidence of OASIS with SVD and forceps delivery in last 10 years is therefore both clinically and statistically significant.
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Figure 4. Incidence of OASIS.
that particular mode of delivery), there has been a significant rise in the incidence of OASIS in patients with SVD, from 1.0% in 2001 to 3.14% in 2010. Though the number of ventouse deliveries has fallen overall in the last 10 years, the percentage of women who sustained OASIS with ventouse delivery increased from 0.6% in 2001 to 2.65% in 2010.
We looked at various risk factors in the group of women with OASIS; number of women with OASIS and associated risk factor/total number of women with OASIS in that particular year (Figure 10). Rate of episiotomy with or without instrumental delivery over 10 years was variable, between 34% and 47%. There appeared to be no association with the OASIS rates. The percentage of babies with birth weight ⬎ 4 kg in this group has remained fairly static, with a small drop in year 2002–2004. The percentage of women who had shoulder dystocia and OASIS had increased from 0% in 2001 to 5.0% in 2010. The percentage of women who had OASIS and were induced, has declined from 44% in 2001 to 31% in 2010 There has also been a fall in the percentage of women who sustained OASIS and had a prolonged second stage of labour (⬎ 1 h) (72% in 2001 to 61% 2010). There is a downward trend in the percentage of women
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who sustained OASIS and had received epidural analgesia in labour (53% in 2001 and 33.89% in 2010). We are unable to calculate the risk of sustaining OASIS with these risks factors, as data for the entire population was not available to us.
Interpretation of results There has been an increase in the total number of births in the last 10 years, with a fall in the number of vaginal deliveries. The forceps rate has increased with a decrease in the ventouse rate. There has been steady increase in the rate of OASIS over the last 10 years. We have identified a three-fold increase in rate of OASIS in SVD and forceps, and a four-fold increase with ventouse delivery. The percentage of primiparous women sustaining OASIS has increased.
Discussion The reported incidence of OASIS varies from 0.5% to 6% of all vaginal deliveries in centres where mediolateral episiotomies are practised (Sultan et al. 1994; Walsh et al. 1996; Tetzschner et al. 1996; Zetterstrom et al. 1999; Fitzpatrick et al. 2000; De Leeuw et al. 2001; Jander and Lyrenas 2001). We have seen a significant rise in the rate of OASIS in the last decade in both instrumental and non-instrumental deliveries, with the overall incidence of OASIS of 4.3% in 2010, which is in-line with the published literature. In a national population-based study in Sweden, the incidence of 3rd degree tears was reported to have increased by over 60%, from 1994 to 2004 (Ekeus et al. 2008). Another retrospective crosssectional study in Norwich, UK in 2009, reported the frequency
of anal sphincter tears of 3.2%, with the increase in incidence between 2005 and 2007 (Revicky et al. 2010). Laine et al. (2009), compared the incidence of OASIS in four Nordic countries and found a similar rising trend in the incidence of OASIS (Sweden 0.5% in 1973 to 4.2% in 2004; Norway 1.6% in 1968 to 4.1% in 2004 and Finland 0.1% in 1986 to 0.6% in 2004). The overall birth rates have increased but the rate of SVD is falling and this may reflect increasing incidence of caesarean section. Despite the falling SVD rate, the percentage of women who had SVD and OASIS has increased. In the UK, the Royal College of Obstetricians and Gynaecologists has produced clinical guidelines in recognition of the wide variation in forceps rates between hospitals, and a desire to reduce morbidity through training (Thomas and Paranjothy 2001). The rates of instrumental vaginal delivery range between 10% and 15% (Johanson 2000). These have remained fairly constant, although there has been a change in preference of instrument. In the 1980s, most instrumental vaginal deliveries were by forceps, but by 2000 this had decreased to under a half. Much of the decline has been attributed to an increasing preference for vacuum extraction or for caesarean section when complex vaginal delivery is anticipated (Bofill et al. 1996; Towner et al. 1999). This trend is seen clearly in England, with the rate of forceps delivery being 5.5% and ventouse delivery rate of 6.6% in 2009. However, in Scotland, the rate of forceps delivery has increased from 6.8% in 2001 to 9.7% in 2010, whereas vacuum delivery has declined from 5.6% in 2001 to 2.9% in 2010 (Birth in Scottish Hospitals 2009/2010). We found that in-keeping with Scottish data, in our institution, the rate of forceps delivery increased and rate of ventouse delivery declined over the last 10 years.
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Figure 6. Different modes of vaginal delivery in women with OASIS.
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We also found higher rate of OASIS with forceps delivery than with ventouse delivery. This is consistent with the finding that forceps delivery carries greater risk than ventouse delivery in causing OASIS (Fitzpatrick et al. 2000; Laine et al. 2009). A recent Cochrane review concluded that with forceps, there is significantly increased risk of 3rd and 4th degree perineal tears (with or without episiotomy) (O’Mahony et al. 2010). This is most likely due to the increased diameter of the fetal head with forceps delivery; a finding that also agrees with the published literature. The increase in the rate of forceps delivery might explain the increase in the number of OASIS associated with forceps but there has been a rise in the percentage of women who had forceps delivery and OASIS. There was a fall in the incidence of OASIS in 2008, which corresponds to the decline in the rate of OASIS in women who had forceps and ventouse assisted delivery in that year but the rate of forceps delivery followed an upward trend. In our institution, although the number of ventouse deliveries has decreased and the percentage of women who sustained OASIS due to ventouse delivery has decreased, the actual respective rate of OASIS with ventouse delivery has increased. This raises the question of whether it is due to increased awareness and recognition of such tears or due to other factors such as technique of delivery or role of episiotomy in causing such tears (Groom and Paterson-Brown 2002). Handa et al. (2001) were able to prove that the clinical diagnosis of OASIS improved by increased vigilance. In our institution, we have also noticed increased incidence of OASIS since 2003/2004, when the OASIS training course in perineal anatomy and recognition of severe perineal trauma was started. However, the incidences have increased since then and have still not plateaued, which we would expect if it was simply recognition increasing the incidence. Therefore, we think that the rising trend in OASIS cannot be explained only by increased awareness and recognition of such tears. Changing practices towards the second stage of labour could have influenced the higher proportion of OASIS. Various studies have reported contradictory findings on whether episiotomy is related to an increased risk of OASIS. Systematic reviews of RCT and some earlier studies (Argentine Incidence of OASIS
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Figure 8. Percentage of primiparous women delivered in last 10 years.
Episiotomy Trial Collaborative Group 1993; Walsh et al. 1996; Carroli and Belizan 2000; Yousef et al. 2005; Dandolu et al. 2005; Andrew et al. 2006; Mikolajczyk et al. 2008; Alperin et al. 2008; Murphy et al. 2009) suggest that mediolateral episiotomy was associated with an increased risk of OASIS or there was statistically no significant difference in the rate of OASIS. De Leeuw et al. (2001) showed a protective effect of episiotomy in their study. A study by Revicky et al. (2010) showed mediolateral episiotomy was associated with lower incidence of OASIS. However, the method and technique of mediolateral episiotomy should be considered. A study by Andrews et al. (2005) investigated potential differences in the cutting of mediolateral episiotomy between doctors and midwives. No midwife and only 13 (22%) doctors performed truly mediolateral episiotomies. It appears that the majority of episiotomies are not truly mediolateral but closer to the midline. More focussed training in the mediolateral episiotomy technique is recommended. Vertex vaginal delivery with no mediolateral episiotomy has a 1.4 times higher risk of sustaining OASIS than those with it (Revicky et al. 2010). Ekeus et al. (2008) found mediolateral episiotomy to be related to an increase in incidence of OASIS with SVD but protective for instrumental deliveries. In our study, the percentage of women who sustained OASIS and had episiotomy was variable and all women who had instrumental delivery were documented as having mediolateral episiotomies. Again the data for the entire population could not be obtained and therefore we cannot compare the rate of OASIS with and without episiotomy. The result of case–controlled study (Eogan et al. 2006) revealed that a smaller angle of episiotomy is more likely to lead to OASIS. They calculated a 50% relative reduction in the risk of OASIS for every 6.3% increment in the angle of episiotomy. Lateral episiotomy by indication is the method used in Finland, where the frequency of OASIS is lowest among the four Nordic countries (Laine et al. 2009). This leads to the suggestion of better training of obstetric and midwifery staff in the better routines of episiotomy techniques and may be trending towards lateral episiotomy to gain better results. In our study population, we did not find any increase in the rate of association of various risk factors in the group of women who sustained OASIS, apart from the rising incidence of primiparous women sustaining OASIS. However, as the data are collected retrospectively, we were unable to calculate the relative risk of sustaining OASIS with different risks factors. Primiparity is one of the most important risk factors, since primiparous women have a 10-fold increase risk of OASIS (Moller Bek and Laurberg 1992; De Leeuw et al. 2001; Eogan et al. 2006). During the past decade, there have been major changes in both obstetric and midwifery practice in UK. Both newborn babies and mothers are getter bigger; mums are getting older and the use of epidural analgesia is increasing. At the same time, the rate of caesarean section has increased (Thomas and Paranjothy 2001).
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Figure 10. Trend of various risk factors in women with OASIS.
Manual perineal protection is little investigated. The method of protecting the perineum when the baby’s head is delivering is described in old books for midwives but not in the new books (Johanson and Menon 2000)! This might signal that perineal protection might not be considered as a routine part of modern obstetrics and midwifery practice. Also, alternative birth positions have become more common and visualising of the perineum has become more difficult or is considered unnecessary. There may be a tendency not to guard the perineum (hands-off approach) during the delivery of the head. One of the possible reasons can be as a result of the HOOP trial (Murphy et al. 2009). Although the primary outcome was to asses pain after 10 days of delivery, it is often taken as evidence to disregard perineal support during delivery of the head (de Souza Caroci da costa and Gonzalez Riesco 2006). Various studies have shown manual protection of the perineum to be protective against OASIS. In an international trial in Norway (Laine et al. 2008) by teaching and doing the classic method of delivering the fetal head, the incidence of OASIS decreased from 4.03% to 1.17%. Hirsch et al. (2008) managed to reduce the incidence of lacerations from 42% to 26% by changing clinical recommendations through departmental lectures, distributing articles and manuals and training physicians. Trochez et al. (2011) in an observational postal questionnaire found that midwives prefer the ‘hands-off ’ method. Lessexperienced midwives were more likely to prefer the ‘hands-off ’ and a higher proportion of midwives in the ‘hands-off ’ group would never do an episiotomy. This may be because of the perceived lack of clinical need for episiotomies, but is also likely to be due to experience and confidence in performing episiotomies. We were unable to obtain data on whether perineal protection/ hands-on technique was used in our population, due to the retrospective nature of the study and this data was not recorded in the system.
Conclusion We conclude that the incidence of OASIS has increased in our institution over the last decade. The rate of forceps delivery had increased and the SVD rate is falling. The rise in OASIS is seen in both SVD and instrumental deliveries. However, there has been no significant increase in the incidence of many of the associated risks factors with OASIS. The rise in OASIS can be partly explained due to increased awareness and recognition of such tears. However, the change in practices (episiotomy/perineal support) may be contributing factors.
Acknowledgement We would like to thank all those who have helped with the collection of the data and Mr David Young, statistician at the Strathclyde University, for statistical advice. Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
References Alperin M, Krohn MA, Parvianien K. 2008. Episiotomy and increase in the risk of obstetric laceration in subsequent vaginal delivery. Obstetrics and Gynecology 111:1274–1278. Andrew V, Sultan AH, Thakar R, Jones PW. 2006. Risk factors for obstetrics anal sphincter injury: a prospective study. Birth 33:117–122. Andrew V, Thakar R, Sultan AH, Jones PW. 2007. Evaluation of postpartum perineal pain and dyspareunia – a prospective study. European Journal of Obstetrics, Gynecology, and Reproductive Biology 137:152–156. Andrews V, Thakar R, Sultan AH, Jones PW. 2005. Are mediolateral episiotomies actually mediolateral? British Journal of Obstetrics and Gynaecology 112:1156–1158. Argentine Episiotomy Trial Collaborative Group. 1993. Routine versus selective episiotomy: a randomised controlled trial. Lancet 342:1517–1518. Bofill JA, Rust OA, Perry KG, Roberts WE, Martin RW, Morrison JC. 1996. Operative vaginal delivery: a survey of fellows of ACOG. Obstetrics and Gynecology 88:1007–1010. Borello-France D, Burgio KL, Richter HE, Zyczynski H, Fitzpatrick Fitzgerald MP et al. 2006. Fecal and urinary incontinence in primiparous women. Obstetrics and Gynecology 108:863–872. Brick A, Layte R. 2009. ESRI working paper 309. Recent trends in the caesarean section rate in Ireland 1999–2006. Dublin: The Economic and Social Research Institute. Carroli G, Belizan J. Episiotomy for vaginal birth. 2000. Cochrane Database of Systematic Reviews (2):CD000081. Dandolu V, Chatwani A, Harmanli O, Floro C, Gaughan JP, Hernandex E. 2005. Risk factors for obstetric anal sphincter injury. International Urogynecology Journal and Pelvic Floor Dysfunction 16:304–307. De Leeuw JW, Strujik PC, Vierhout ME, Wallenburg HC. 2001. Risk factors for third degree perineal ruptures during delivery. British Journal of Obstetrics and Gynaecology 108:383–387. de Souza Caroci da costa A, Gonzalez Riesco ML. 2006. A comparison of hands off and hands on technique for decreasing perineal laceration at birth. Journal of Midwifery and Women’s Health 51:106–111. Ekeus C, Nilsson E, Gottvall K. 2008. Increasing incidence of anal sphincter tears among primiparous in Sweden: A population based register study. Acta Obstetricia et Gynecologica Scandinavica 87:564–573. Eogan M, Daly L, O’Connell PR, O’Herlihy C. 2006. Does the angle of episiotomy affect the incidence of anal sphincter injury? British Journal of Obstetrics and Gynaecology 113:190–194. Fitzpatrick M, Fynes M, Cassidy M, Behan M, O’Connell PR, O’Herlihy C. 2000. Prospective study of the influence of parity and operative technique on the outcome of primary anal sphincter repair following obstetric injury. European Journal of Obstetrics, Gynecology, and Reproductive Biology 89:159–163.
Downloaded by [York University Libraries] at 04:48 07 November 2015
Current trend in obstetric anal sphincter injuries 849 Groom KM, Paterson-Brown S. 2002. Can we improve the diagnosis of third degree tears? European Journal of Obstetrics, Gynecology, and Reproductive Biology 101:19–21. Handa VL, Danielsen BH, Gilbert VM. 2001. Obstetric anal sphincter lacerations. Obstetrics and Gynecology 98:225–230. Hirsch E, Haney EI, Gordon TE, Silver RK. 2008. Reducing higher order perineal laceration during operative delivery. American Journal of Obstetrics and Gynecology 198:668.e1–e5. Jander C, Lyrenas S. 2001. Third and fourth degree perineal tears: predictor factors in referral hospital. Acta Obstetricia et Gynecologica Scandinavica 80:229–234. Johanson RB, Menon BK. 2000. Vacuum extraction vs forceps for assisted vaginal delivery. Cochrane Database of Systematic Reviews (3): CD000224. Johanson RB. 2000. Instrumental vaginal delivery. London: Royal College of Obstetricians and Gynaecologists. Laine K, Gissler M, Pirhonen J. 2009. Changing incidence of anal sphincter injuries in four Nordic countries through the last decades. European Journal of Obstetrics, Gynecology, and Reproductive Biology 146:71–75. Laine K, Pirhonen T, Rolland R, Pirhonen J. 2008. Decreasing the trend of anal sphincter tears during delivery. Obstetrics and Gynecology 111:1053–1057. McCandlish R, Bowler U, van Asten H, Berridge G, Winter C, Sames L et al. 1998. A randomised controlled trial of care of the perineum during second stage of labour. British Journal of Obstetrics and Gynaecology 105:1262–1272. Mikolajczyk RT, Zhang J, Troendle J, Chan L. 2008. Risk factor for birth canal lacerations in primiparous women. American Journal of Perinatology 25:259–264. Moller Bek K, Laurberg S. 1992. Intervention during labour: Risk factor associated with complete tear of anal sphincter. Acta Obstetricia et Gynecologica Scandinavica 71:520–524. Murphy DJ, McLeod M, Bahl R, Goyder K, Howarth L, Strachan B. 2009. A randomised controlled trial of routine vs. restrictive use of episiotomy at operative vaginal delivery: a multicentre pilot study. Obstetrical and Gynecological Survey 64:220–221. O’Mahony F, Hofmeyr GJ, Menon V. 2010. Choice of instruments for assisted vaginal delivery. Cochrane Database of Systematic Reviews (11):CD005455.
Parnell C, Langhoff-Roos J, Moller H. 2001. Conduct of labour and rupture of sphincter Ani. Acta Obstetricia et Gynecologica Scandinavica 80: 356–361. Pirhonen JP, Gernman SE, Haadem K et al. 1998. Frequency of anal sphincter rupture at delivery in Sweden and Finland- result of difference in manual help to the baby’s head. Acta Obstetricia et Gynecologica Scandinavica 77:974–977. Revicky V, Nirmal D, Mukhopadhyay S, Morris EP, Nieto JJ. 2010. Could a mediolateral episiotomy prevent obstetric anal sphincter injury? European Journal of Obstetrics and Gynecology and Reproductive Biology 150:142–146. Samuelson E, Ladfors L, Wennerholm UB, Gareberg B, Nyberg K, Hegeberg H. 2000. Anal sphincter tear: prospective study of obstetrics risk factors. British Journal of Obstetrics and Gynaecology 107:926–931. Sultan AH, Kamm MA, Hudson CN, Bartram CI. 1994. Third degree obstetric anal sphincter tears: risk factors and outcome of primary repairs. British Medical Journal 308:887–891. Tetzschner T, Sorenson M, Lose G, Christiansen J. 1996. Anal and urinary incontinence in women with obstetric anal sphincter rupture. British Journal of Obstetrics and Gynaecology 103:1034–1040. Thomas J, Paranjothy S. 2001. National sentinel caesarean section audit report. London: Royal College of Obstetricians and Gynaecologists Clinical Effectiveness Support Unit. Towner D, Castro MA, Eby-Wilkens E, Gilbert WM. 1999. Effect of mode of delivery in nulliparous women on neonatal intracranial injury. New England Journal of Medicine 341:1709–1714. Trochez R, Waterfield M, Freeman RM. 2011. Hands on or hands off the perineum: a survey of care of the perineum in labour (HOOPS). International Urogynecology Journal 22:1279–1285. Walsh CJ, Mooney EF, Upton GJ, Motson RW. 1996. Incidence of third degree tear in labour and outcome after primary repair. British Journal of Surgery 83:218–221. Yousef R, Ramalingam U, Macleod M, Murphy DJ. 2005. Cohort study of maternal and fetal morbidity in relation to use of episiotomy at instrumental vaginal delivery. British Journal of Obstetrics and Gynaecology 112:941–945. Zetterstrom J, Lopez A, Anzen B, Norman M, Holmstrom B, Mellgran A 1999. Anal sphincter tear at vaginal delivery: risk factors and clinical outcomes of primary repair. Obstetrics and Gynecology 94:21–28.
