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OBSTETRICS

Third- and fourth-degree perineal tears: prevalence and risk factors in the third millennium Asnat Groutz, MD; Joseph Hasson, MD; Anat Wengier, MD; Ronen Gold, MD; Avital Skornick-Rapaport, MD; Joseph B. Lessing, MD; David Gordon, MD OBJECTIVE: We sought to assess the modern prevalence and risk fac-

tors for third- and fourth-degree perineal tears. STUDY DESIGN: The study population comprised 38,252 women who delivered in one medical center, from January 2005 through December 2009, and met the following inclusion criteria: singleton pregnancy, vertex presentation, and vaginal delivery. Of these, 96 women (0.25%) sustained third- or fourth-degree perineal tears. Maternal and obstetric variables were compared between women with vs without severe perineal tears. RESULTS: Five variables were found to be statistically significant inde-

pendent risk factors: Asian ethnicity (odds ratio [OR], 8.9; 95% confi-

dence interval [CI], 4.2–18.9), primiparity (OR, 2.4; 95% CI, 1.5–3.7), persistent occipito posterior (OR, 2.1; 95% CI, 1– 4.5), vacuum delivery (OR, 2.7; 95% CI, 1.6 – 4.6), and heavier birthweight (OR, 1.001; 95% CI, 1–1.001). CONCLUSION: Severe perineal tears are uncommon in modern obstet-

ric practice. Significant risk factors are Asian ethnicity, primiparity, persistent occipito posterior, vacuum delivery, and heavier birthweight. Key words: delivery, labor, prevalence, risk factors, severe perineal tears

Cite this article as: Groutz A, Hasson J, Wengier A, et al. Third- and fourth-degree perineal tears: prevalence and risk factors in the third millennium. Am J Obstet Gynecol 2011;204:347.e1-4.

V

aginal delivery is well known to be associated with anal sphincter injury. Such injury may be either occult, diagnosed by endosonographic imaging of the anal sphincter after otherwise normal vaginal delivery, or clinically overt perineal tears. Perineal tears are further classified into mild (first and second degree) and severe (third and fourth degree) according to the depth of injury.1 Earlier sonographic studies demonstrated up to 35% incidence rate of occult internal or external anal sphincter disruption following first vaginal delivery.2 Mild perineal tears are also very common and

From the Urogynecology and Pelvic Floor Unit, Department of Obstetrics and Gynecology, Lis Maternity Hospital, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. Received Aug. 25, 2010; revised Oct. 21, 2010; accepted Nov. 9, 2010. Reprints: Asnat Groutz, MD, Urogynecology, Lis Maternity Hospital, Tel Aviv Sourasky Medical Center, 6 Weizman St., Tel Aviv, Israel. agroutz@yahoo.com. 0002-9378/$36.00 © 2011 Mosby, Inc. All rights reserved. doi: 10.1016/j.ajog.2010.11.019

were reported to occur in up to 73% of nulliparous parturients.3 Severe perineal tears are much less common. Reported prevalence rates vary from 0.6-8% among different populations, and in some countries a significant rise over the last 3 decades was documented.4-9 There is no consensus regarding preventive measures and clinical management of severe perineal tears. There are also conflicting data regarding the significance of various obstetric risk factors for such tears.10-13 Among multiple examined obstetric parameters, only primiparity, assisted forceps delivery, persistent occipito posterior position, and heavier birthweight were consistently found as significant risk factors. Modern obstetric practice underwent some major changes during the third millennium: there is a significant rise in cesarean delivery rate, the preferred delivery mode for breech presentation is cesarean section, many obstetric wards avoid using forceps, women defer their first pregnancy and delivery to older age, and ethical, financial, and legal issues affect medical management. There is also an increased medical and public awareness of various aspects of maternal wellbeing, as well as long-term impacts of

childbirth-induced pelvic floor injury. Yet, up to 60% of women who experienced severe perineal tears still develop anal incontinence, perineal pain, or dyspareunia. Establishment of risk factors for such tears may enable earlier identification of patients at risk and the use of appropriate preventive measures. The present study was undertaken to evaluate the modern prevalence and risk factors for third- and fourth-degree perineal tears in a single university-affiliated maternity hospital with approximately 10,000 deliveries per year.

M ATERIALS AND M ETHODS A total of 50,905 consecutive women delivered in Lis Maternity Hospital, Tel Aviv Sourasky Medical Center, from January 2005 through December 2009. Of these, 43.9% were primiparae and 56.1% multiparae. The study population comprised 38,252 women (75.1% of the obstetric cohort) who met the following inclusion criteria: singleton pregnancy, vertex presentation, and vaginal delivery. Multifetal pregnancies, breech presentations, and cesarean deliveries were excluded from the analysis. Of the study population, 2186 (5.7%) women underwent instrumental assisted deliveries; all

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were carried out by vacuum extraction. Epidural analgesia was administered in 77% of the women. Dysfunctional labor was defined by clinical criteria proposed by the American College of Obstetricians and Gynecologists.14 According to these criteria, prolonged second stage is defined as duration of ⬎2 or 3 hours depending on parity and the use of epidural anesthesia. A third-degree tear was defined as injury to the perineum involving the anal sphincter muscles. A fourth-degree tear was defined as injury to the perineum involving the rectal mucosa.1 In our medical center, uncomplicated vaginal deliveries are conducted by midwives, while vacuum-assisted deliveries are performed by obstetricians. Routine delivery management includes active manual support of the perineum and the fetal head when crowning through the vagina. Mediolateral episiotomies are done selectively. The epidural analgesia includes initial 20-mL bolus of 0.083% bupivacaine and 2 ␮g/kg fentanyl followed by patient-controlled epidural analgesia (PCEA) administration. The PCEA regime comprises 0.083% bupivacaine and 2 ␮g/kg fentanyl in a 5-mL/h continuous infusion, and 5-mL PCEA boluses every 10 minutes, up to a total of 30 mL/h. Epidural analgesia is administered during the active phase of labor and continued throughout labor and delivery. Usually, this epidural regime enables an adequate sensory block. If motor block is suspected, the infusion is discontinued and an anesthesiologist is called to evaluate the patient. All perineal injuries, including episiotomies and tears, are sutured by obstetricians. Cases of third- and fourth-degree tears are verified and managed by an experienced surgeon. Demographic, medical, and obstetric data are prospectively documented and stored in a computerized database. Obstetric parameters include: maternal age, ethnicity, parity, height, weight before pregnancy and at delivery, gestational age at delivery, labor induction or augmentation, length of first and second stages of labor, use and type of analgesia (epidural, narcotics), mode of delivery (spontaneous, vacuum, cesarean section), mediolateral episiotomy, 347.e2

www.AJOG.org perineal tears, newborn’s Apgar scores, birthweight, and sex. During the study period, third- or fourth-degree perineal tears occurred in 96 women (0.25% of the study population). Data from these deliveries were analyzed and compared to data from 38,156 vaginal deliveries without severe perineal tears. The study protocol was approved by the local hospital Helsinki committee. Statistical analysis was performed using Student t test for continuous data or ␹2 for categorical data. P ⬍ .05 was considered statistically significant. Data are summarized as mean ⫾ SD, or percentage according to the variables. All variables that were found to be statistically significant in the univariate analysis were entered into a multivariate logistic regression model to identify independent risk factors. Software (Statistical Package for Social Sciences, version 15.0; SPSS Inc, Chicago, IL) was used for the multivariate analysis.

gestational age at delivery, longer duration of the second stage of labor, persistent occipito posterior position, assisted vacuum extraction, and heavier newborn birthweight were significantly more common among women who had third- or fourth-degree perineal tears than those who did not. Further comparison of vacuum deliveries with vs without severe perineal tears revealed significantly higher rates of Asian ethnicity and persistent occipito posterior position among cases of severe tears (20% vs 3.2%, and 35% vs 12%; respectively). Of the variables that were found to be statistically significant in the univariate analysis, 5 were found to be statistically significant independent risk factors in the multivariate logistic regression model: Asian ethnicity, primiparity, persistent occipito posterior position, assisted vacuum delivery, and heavier newborn birthweight (Table 2).

C OMMENT R ESULTS Ninety-six (0.25%) women, 65 (68%) of whom were primiparae, had third- (84 women) or fourth- (12 women) degree perineal tears. The mean age of the women was 30.5 ⫾ 4.8 (range, 20 – 41 years). Fourteen (14.6%) women were of Asian origin (12 of whom were from the Philippines). Forty-five (47%) women received oxytocin for either labor induction or augmentation, and 74 (77%) received epidural analgesia. Mean duration of the second stage of labor was 83 ⫾ 68 minutes. Fifteen (16%) women had, by definition, prolonged second stage. Seventy-six (79%) women had spontaneous vaginal deliveries and 20 (21%) others underwent assisted vacuum delivery. Persistent occipito posterior position was recorded in 8 (8.3%) cases. A mediolateral episiotomy was undertaken in 37% of the 76 spontaneous vaginal deliveries, and in all of the vacuum extractions. Mean birthweight was 3369 ⫾ 469 g, 6 (6.3%) of the newborns were ⬎4000 g. Univariate comparison of the study and control groups is presented in Table 1. Of the various obstetric parameters, Asian ethnicity, primiparity, advanced

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Results of our study demonstrate a very low prevalence rate of third- and fourthdegree perineal tears in a single university hospital with approximately 10,000 deliveries per year. This rate (0.25%) is much lower than previously reported. Prevalence of severe perineal tears varies considerably by different populations, location, and date. Studies from the early 1990s reported a wide range of prevalence rates: a study from North America reported as much as 7.3% of thirdand fourth-degree perineal tears among 258,507 vaginal deliveries recorded in Pennsylvania during 1990 through 1991.5 A similar study from Europe reported 1.94% of third-degree perineal tears among 284,783 vaginal deliveries recorded in the 1994 through 1995 Dutch National Obstetric Database.10 Much lower rates of severe perineal tears were reported by earlier British4 and Israeli15 studies (0.6% and 0.1%, respectively). Although modern obstetric practice underwent some major changes during the last decade, there are almost no up-to-date data regarding the current prevalence of severe perineal tears. A relatively small British study of 2278 vaginal deliveries revealed 1.58% incidence


Obstetrics

www.AJOG.org rate of third- and fourth-degree perineal tears.7 Laine et al9 examined the incidence of severe perineal tears in 4 Nordic countries through the last decades. The incidence of severe perineal tears was found to be significantly higher in Denmark, Norway, and Sweden compared to Finland. Also, there was a significant increment in the incidence over the last 3 decades: in Denmark from 0.4% in 1976 through 1987 to 3.6% in 2006; in Norway from 1.6% in 1968 to 4.1% in 2004; in Sweden from 0.5% in 1973 to 4.2% in 2004; and in Finland from 0.1% in 1987 to 1.0% in 2006. The investigators noted that contrary to Finland in which active manual protection of the perineum during vaginal deliveries is routinely used, this classic approach had lost its importance in Denmark, Norway, and Sweden during the last decades. Although controversial, this change in obstetric policy may be responsible for the significant lower rate of severe perineal injury recorded in Finland. However, it is also possible that better registration routines, or better diagnosis, contribute to the observed incidence rise in the other Nordic countries. This latter speculation is further supported by another study in which 241 women were examined by an experienced research fellow immediately after their first vaginal delivery.16 Of the 241 women, 59 (25%) sustained thirdor fourth-degree tears! Of these, 30 occurred in women whose deliveries were conducted by midwives, who missed 26 (87%) cases, and 29 occurred in women delivered by doctors, who failed to identify 7 (24%) cases. Yet, even if, as suggested by the quoted study, up to 87% of the severe tears are underdiagnosed, the current incidence of such tears in our medical center is still very low, ⬍1% of all vaginal deliveries. Similarly to Finland, this very low incidence may be partially explained by the policy of active manual support of the perineum, employed in our medical center. In addition, some of the established risk factors, such as forceps deliveries and routine use of episiotomies, were eliminated from our routine obstetric practice during the last decade. Among various obstetric parameters, primiparity, assisted forceps delivery,

Research

TABLE 1

Patient’s characteristics Mean ⴞ SD or n (%)

Study group n ⴝ 96

Control group n ⴝ 38,156

P

Age, y

30.5 ⫾ 4.8

Asian ethnicity

14 (14.6)

31.1 ⫾ 4.7

BMI prepregnancy

21.9 ⫾ 3.4

BMI at delivery

27.1 ⫾ 3.5

Primipara

65 (68)

Gestational age, wk

39.6 ⫾ 1.4

Epidural analgesia

74 (77)

Second stage of labor, min

83 ⫾ 68

Prolonged second stage

15 (16)

4326 (11)

.195

Vacuum extraction

20 (21)

2166 (5.7)

⬍ .001

8 (8.3)

1268 (3.3)

.015

.219

..............................................................................................................................................................................................................................................

552 (1.4)

⬍ .001

..............................................................................................................................................................................................................................................

22.1 ⫾ 3.7

.568

..............................................................................................................................................................................................................................................

27.3 ⫾ 3.9

.704

..............................................................................................................................................................................................................................................

16,480 (43)

⬍ .001

..............................................................................................................................................................................................................................................

39.2 ⫾ 1.5

.012

..............................................................................................................................................................................................................................................

29,310 (77)

.991

..............................................................................................................................................................................................................................................

62 ⫾ 61

⬍ .001

.............................................................................................................................................................................................................................................. .............................................................................................................................................................................................................................................. ..............................................................................................................................................................................................................................................

Persistent occipito posterior

..............................................................................................................................................................................................................................................

Birthweight, g

3369 ⫾ 469

3252 ⫾ 445

.01

6 (6.3)

1613 (4.2)

.304

56 (58.3)

19,166 (50.2)

.126

..............................................................................................................................................................................................................................................

Birthweight ⱖ4000 g

..............................................................................................................................................................................................................................................

Newborn male

..............................................................................................................................................................................................................................................

BMI, body mass index. Groutz. Severe perineal tears in the third millennium. Am J Obstet Gynecol 2011.

persistent occipito posterior position, and birthweight of ⬎4000 g were previously found to be significantly associated with severe perineal tears.17 Other, less established, risk factors include maternal age, postdate pregnancies, induction of labor, prolonged second stage, precipitate labor, epidural anesthesia, and various maternal birth positions.17 Results of the present study support some of these risk factors, ie, primiparity, persistent occipito posterior position, and heavier birthweight, but also emphasize the importance of Asian ethnicity and assisted vacuum deliveries.

The Lis Maternity Hospital is a tertiary medical center, located within the center of Tel Aviv, Israel. Obstetric population is relatively homogeneous, composed mainly of middle-class Israeli women. During the last decade there was a growing population of foreign workers in Tel Aviv area. Throughout the study period, a total of 566 Asiatic women, 485 of whom were from the Philippines, delivered in our hospital (1.5% of the total study population). Of the 96 women who had severe perineal tears, 14 (15%) were of Asian origin. Thus, the incidence of severe tears among Asiatic women was

TABLE 2

Significant independent risk factors in multivariate logistic regression model Variable

Odds

95% CI

P

Asian ethnicity

8.94

4.23–18.86

⬍ .001

Primipara

2.38

1.51–3.75

⬍ .001

Vacuum extraction

2.68

1.57–4.55

⬍ .001

Persistent occipito posterior

2.11

1.0–4.46

Birthweight, g

1.001

1.0–1.001

.............................................................................................................................................................................................................................................. .............................................................................................................................................................................................................................................. ..............................................................................................................................................................................................................................................

.049

..............................................................................................................................................................................................................................................

⬍ .001

..............................................................................................................................................................................................................................................

CI, confidence interval. Groutz. Severe perineal tears in the third millennium. Am J Obstet Gynecol 2011.

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2.5%. High prevalence of severe perineal tears among Asian women delivering in Western countries was previously reported by others, and is thought to be associated with a relatively short perineum that is less likely to stretch well, or relatively higher birthweights secondary to dietary changes.6,17-20 Another interesting possible explanation is the lack of effective communication between the foreign women and the local midwifes during the course of labor and delivery.6 There are almost no data regarding obstetric parameters and prevalence of perineal tears among Asian women in their own countries. Nakai et al21 studied the incidence and risk factors for severe perineal tears among Japanese women. Of 7946 singleton vaginal vertex deliveries that occurred from 1997 through 2005, 135 women (1.7%) had severe perineal tears. Main risk factors were midline episiotomy, forceps, oxytocin use, and shorter attendant experience. In our hospital we do not use midline episiotomy or forceps. Nevertheless, the incidence of severe perineal tears among Asian women delivering in our hospital was 2.5%, 10-fold higher than the incidence in the general obstetric population. Results of the present study also suggest that assisted vacuum deliveries are associated with increased risk for severe perineal tears. Previous studies demonstrated an increased risk of perineal and vaginal trauma following forceps deliveries compared with vacuum deliveries.22-25 Forceps deliveries are not performed in our medical center, so no comparison can be made between the 2 instrumental methods. Furthermore, it is quite possible that the main cause of perineal trauma during instrumental assisted deliveries is the obstetric indication for such an intervention, namely prolonged second stage and/or persistent occipito posterior position, rather than the type of the instrument used per se. Thus, avoiding instrumental intervention may facilitate prolonged distention of the vagina by the fetal head, causing greater perineal injury. In conclusion, third- and fourth-degree perineal tears were diagnosed in 0.25% of vaginal deliveries in a single 347.e4

www.AJOG.org university-affiliated maternity hospital. The most significant risk factors for such tears were maternal Asian ethnicity, primiparity, persistent occipito posterior position, assisted vacuum delivery, and heavier newborn birthweight. We believe that the very low incidence of severe perineal tears may be explained by better prenatal care allowing early and more accurate sonographic detection of heavier babies, early identification of patients at risk, and changes in daily obstetric practice such as active manual support of the perineum, avoidance of forceps deliveries, avoidance of midline episiotomies, selective use of mediolateral episiotomies, and 25% rate of cesarean deliveries. We also believe that some injuries are underdiagnosed and the true incidence of severe perineal tear is higher. Thus, early identification of women at risk may facilitate the use, or avoidance, of certain obstetric interventions to minimize the f occurrence of such injuries. REFERENCES 1. Royal College of Obstetricians and Gynaecologists. Management of third and fourth degree perineal tears following vaginal delivery; RCOG guideline no. 29. London: RCOG Press; 2001. 2. Sultan AH, Kamm MA, Bartram CI, Hudson CN, Anal-sphincter disruption during vaginal delivery. N Engl J Med 1993;329:1905-11. 3. Samuelsson E, Ladrors L, Lindblom BG, Hagberg H. A prospective observational study on tears during vaginal delivery: occurrences and risk factors. Acta Obstet Gynecol Scand 2002;81:44-9. 4. Williams A. Third-degree perineal tears: risk factors and outcome after primary repair. J Obstet Gynaecol 2003;23:611-4. 5. Dandolu V, Chatwani A, Harmanli O, Floro C, Gaughan JP, Hernandez E. Risk factors for obstetrical anal sphincter lacerations. Int Urogynecol J 2005;16:304-7. 6. Dahlen HG, Ryan M, Homer C, Cooke M. An Australian prospective cohort study of risk factors for severe perineal trauma during childbirth. Midwifery 2007;23:196-203. 7. Eskandar O, Shet D. Risk factors for 3rd and 4th degree perineal tear. J Obstet Gynaecol 2009;29:119-22. 8. Valbo A, Gjessing L, Herzog C, Goderstad JM, Laine K, Valset AM. Anal sphincter tears at spontaneous delivery: a comparison of five hospitals in Norway. Acta Obstet Gynecol 2008;87:1176-80. 9. Laine K, Gissler M, Pirhonen J. Changing incidence of anal sphincter tears in four Nordic countries through the last decades. Eur J Obstet Gynecol Reprod Biol 2009;146:71-5.

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10. De Leeuw JW, Struijk PC, Vierhout ME, Wallenburg HC. Risk factors for third degree perineal ruptures during delivery. BJOG 2001; 108:383-7. 11. Jander C, Lyrenas S. Third and fourth degree perineal tears: predictor factors in a referral hospital. Acta Obstet Gynecol Scand 2001;80: 229-34. 12. Riskin-Mashiah S, O’Brian Smith E, Wilkins IA. Risk factors for severe perineal tear: can we do better? Am J Perinatol 2002;19:225-34. 13. Christianson LM, Bovbjerg VE, McDavitt EC, Hullfish KL. Risk factors for perineal injury during delivery. Am J Obstet Gynecol 2003; 189:255-60. 14. American College of Obstetricians and Gynecologists. ACOG technical bulletin. Dystocia and the augmentation of labor. Number 218 – December 1995 (replaces No. 137, December 1989, and No. 157, July 1991). Int J Gynaecol Obstet 1996;53:73-80. 15. Sheiner E, Levy A, Walfisch A, Hallak M, Mazor M. Third degree perineal tears in a university medical center where midline episiotomies are not performed. Arch Gynecol Obstet 2005;271:307-10. 16. Andrews V, Sultan AH, Thakar R, Jones PW. Risk factors for obstetric anal sphincter injury: a prospective study. Birth 2006;33:117-22. 17. Byrd LM, Hobbiss J, Tasker M. Is it possible to predict or prevent third degree tears? Colorectal Dis 2005;7:311-8. 18. Goldberg J, Hyslop T, Tolosa J, et al. Racial differences in severe perineal lacerations after vaginal delivery. Am J Obstet Gynecol 2003; 188:1063-7. 19. Dhawan S. Birth weights of infants of first generation Asian women in the United Kingdom compared with second generation Asian women. BMJ 1995;311:86-8. 20. Schwartz N, Seubert DE, Mierlak J, Arslan AA. Predictors of severe perineal lacerations in Chinese women. J Perinat Med 2009;37:109-13. 21. Nakai A, Yoshida A, Kawabata I, et al. Incidence and risk factors for severe perineal laceration after vaginal delivery in Japanese patients. Arch Gynecol Obstet 2006;274:222-6. 22. Sultan AH, Kamm MA, Hudson CN, Thomas JM, Bartram CI. Anal sphincter trauma during instrumental delivery: a comparison between forceps and vacuum extraction. Int J Gynaecol Obstet 1993;43:263-70. 23. Johanson RB, Rice C, Doyle M, et al. A randomized prospective study comparing the new vacuum extractor policy with forceps delivery. Br J Obstet Gynaecol 1993;100:524-30. 24. 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. 25. Bofill JA, Rust OA, Schorr SJ, et al. A randomized prospective trial of the obstetric forceps versus the M-cup vacuum extractor. Am J Obstet Gynecol 1996;175:1325-30.


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