Anal Sphincter Tear after Vaginal Delivery A Retrospective

Anal Sphincter Tear after Vaginal Delivery: A Retrospective Study in Primiparous Women Dr. Siti Nur Aishah Rahmat, Dr. Haslina Sarkawi, Dr. Jamali Wagiman, & Dr. Krishna Kumar Hari Krishnan Department of Obstetric and Gynaecology, Hospital Tuanku Jaafar Seremban, Negeri Sembilan INTRODUCTION There is a considerate concern in vaginal delivery. Obstetric trauma is the major cause of anal incontinence and it has been reported in UK that 5% of the mothers were affected annually [1]. This figure is expected to be higher if we include subclinical anal sphincter injury following vaginal delivery. The classification of sphincter injury as shown in Table 1 which was described by Sultan, has been adopted by International Consultation on Incontinence and the RCOG. Type of tear Definition First-degree Injury to the perineal skin Table 1: Classification of perineal injury [2] Seconddegree Injury to the perineum involving the perineal muscles, but not involving the anal sphincter Third-degree Injury to the perineum involving anal sphincter complex (3 A) <50% of the EAS thickness torn (3 B) >50% of the EAS thickness torn (3 C) Both the EAS and the IAS torn Fourth-degree Injury to the perineum involving anal sphincter complex (both the EAS and the IAS) and anal epithelium Obstetric anal sphincter injury (OASI) which consists of 3 rd and 4 th degree perineal tear is the common precursor of fecal incontinence [3]. It is believed to affect around 5% of mothers in the UK. Incontinence due to OASI increase the cumulative health service costs and affect women’s quality of life [4]. Women who are aware of the potential devastating consequences, may ask for elective caesarean section. However, obstetricians are well known that caesarean section is far more likely to cause maternal morbidity. Thus, this study is initiated using secondary data from Hospital Tuanku Jaafar Seremban. It was conducted among primiparous women as it has been shown in literature that this group of women had higher risk of OASI. This is because, nulliparous has a relatively inelastic perineum, time for perineal stretching during the second stage of labor is often inadequate, and perineal trauma during their first delivery is therefore more likely. TEMPLATE DESIGN © 2008 www. Poster. Presentations. com OBJECTIVES Specific Objectives: 1. To determine the prevalence of anal sphincter tear after vaginal delivery for women having first vaginal delivery without caesarean. 2. To identify risk factors associated with anal sphincter tears. METHODS The material from the study was retrospectively collected over a 5 -year period between 1 January 2007 to 31 December 2011 at Hospital Tuanku Jaafar Seremban. The material was collected by hand extracted from labor room birth registration record. Two groups of women having their first vaginal delivery either those with or those without a recognized anal sphincter tear were selected for analysis. Ø OASI group: Women with anal sphincter tear who delivered vaginally (i. e. third or fourth degree perineal tear). Ø Control group: A control group that included women who delivered vaginally without a clinically recognized anal sphincter tear. (i. e. first and second degree perineal tear). Based on the 5 -year data, a total of 8820 women having their first vaginal delivery was available for analysis. For comparison purpose between both groups, 50 data were used for the control group. Information on demographics and obstetric information were gathered as well for further analysis. Results are presented as mean standard deviation for continuous variable or as percentages for categorical variables. Continuous variables and categorical data in both groups were compared by using two samples t test and Chi-square test respectively. RESULTS AND DISCUSSIONS CONCLUSIONS Anal sphincter tears (3 rd and 4 th degree) were noted in 33 (0. 37%) of the 8820 women who had their first vaginal delivery without caesarean. Out of the 33 cases, 4 of the women had fourth degree perineal tears. The results from our study highlight the low prevalence of anal sphincter tears after first vaginal delivery and this is consistent with previous studies. Based on a previous study in Sweden, the incidence of sphincter injury gradually increased from 0. 7% in 1982 to 2. 9% in 1996 [6]. Furthermore, few other studies conducted in the United States revealed that anal sphincter tears occur in 2 to 19% of vaginal deliveries [7 -9]. Table 2: Characteristics of 83 Primiparous Women With and Without Anal Sphincter Tear Control Characteristic Maternal age (years) Gestational age at delivery (weeks) Birthweight (kg) Head circumference (cm) Mode of delivery Normal Instrumental OASI group (n=33) group (n=50) p-value 26. 6± 4. 1 25. 5± 4. 0 . 248 39. 4± 1. 3 38. 3± 2. 6 <. 005 3. 4± 0. 4 2. 8± 0. 6 <. 005 33. 7± 1. 4 32. 5± 2. 1 <. 005 21 (63. 6%) 12 (36. 4%) 48 (96. 0%) 2 (4. 0%) Additionally, higher gestational age, higher birth weight, higher infant head circumference and instrumental delivery were identified to be the main risk factors. Such information is essential for clinicians to consider for future decisions on obstetric interventions including caesarean sections. Current study was conducted using secondary data. For more accurate detection on anal sphincter tears, postpartum endoanal ultrasound shall be performed. However, due to unavailability of the device during the data collection, the true incidence of OASI especially on ‘occult’ anal sphincter tears could not be determined. Furthermore, the comparison between OASI and control groups cannot be used for statistical interpretation due to small number of samples. REFERENCES Thus, future study shall be conducted on larger samples and include endoanal ultrasound device. 1. Fernando RJ, Sultan AH, Radley S, Jones PW, <. 005 2. Data are expressed as mean±standard deviation or n (%). Based on Table 2, there is significant mean difference between OASI and control groups in terms of gestational age, birth weight and infant head circumference. Furthermore, the mean values for the three factors are higher for OASI group in comparison with control group. Further analysis using the chi-square method, there is significant association between mode of delivery and type of group. The incidence of anal sphincter damage following instrumental delivery is higher (36. 4%) for OASI group when compared with control group (4. 0%). In addition, all of the cases for OASI group involved medio-lateral episiotomy. This is because most of the vaginal deliveries for primigravida (about 94%) in Hospital Tuanku Jaafar Seremban involved episiotomy. 3. 4. 5. 6. 7. 8. Johanson RB. Management of obstetric anal sphincter injury: a systematic review and national practice survey. BMC Health Serv Res 2002; 2: 9. Adams EJ, Fernando RJ. RCOG Green Top Guideline: Management of third and fourth degree perineal tears following vaginal delivery. 2001 en Top Guideline. 2001 Fernando RJ. Anal sphincter injury at birth. OBG Management 2005; 22 -39. Mellgren A, Jensen LL, Zetterstrom JP, Wong WD, Hofmeister JH, Lowry AC. Long-term cost of faecal incontinence secondary to obstetric injuries. Dis Colon Rectum. 1999; 42: 857– 867. Coombs CA, Robertson PA, Laros RK. 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