Retrospective study evaluating risk factors and patient symptoms associated with obstetrical anal spincter injuries at a single teriatry center

Ortega Cárdenes I1, Medina Castellano M1, Montes Posada I2, Fernández Mederos A1, Cruz García A1, Gil González Y1, Castro Marrero B2, García Hernández J1, Martín Martínez A1

Research Type


Abstract Category

Anorectal / Bowel Dysfunction

Abstract 88
E-Poster 1
Scientific Open Discussion ePoster Session 7
Wednesday 4th September 2019
12:45 - 12:50 (ePoster Station 3)
Exhibition Hall
Anal Incontinence Rehabilitation Prevention
1.Servicio de Obstetricia y Ginecología. Hospital Universitario Materno-Infantil de Las Palmas de Gran Canaria, 2.Servicio de Rehabilitación y Medicina Física. Hospital Universitario de Gran Canaria Dr. Negrín

Ismael Ortega Cárdenes




Hypothesis / aims of study
Obstetric Anal Sphincter Injury (OASI) is the most common cause of anal incontinence in women. Despite intrapartum diagnosis and repair 40% will refer anal incontinence (1). Identifying possible risk factors for sustaining an OASI may help in future to change those modifiable risk factors or to establish preventable measures for such injuries. The aim of our study was to determine possible risk factors for sustaining anal sphincter tears and secondly to assess patient symptoms.
Study design, materials and methods
This is a retrospective observational study carried out at a tertiary University Maternity Hospital which included all patients who sustained an OASI during 1st November 2017 and 31st October 2018. Patients were followed-up on by a multidisciplinary team at 2,4 and 6 months after delivery where detailed urogynaecological interview was undertaken and a clinical examination performed at each visit. 4D Translabial ultrasound was performed four months following delivery as described previously (3). 
All deliveries at the authors centre were attended following basic guidelines and procedures. Manual protection of the perineum is mandatory and a rectal examination was consistently performed immediately after delivery to ensure correct diagnosis of the degree of the tear. Although an initial diagnosis was determined by the midwife or physician who attended the delivery, only the staff specialist confirmed and repaired the OASIS following local protocol.  OASI was classified at our unit following Sultan’s classification. Obstetrical data was obtained from the local electronical database (Drago).
During the study period, there were 3303 vaginal deliveries at the author’s center. 63 (1.9%) sustained an OASI however 7 did not return to follow-up leaving a total of 56 patients for primary analysis. Mean age at delivery was 32. Mean body mass index at follow-up was 27kg/m2. Only one delivery (2%) was breech and 55% of patients had epidural analgesia. 84% of women were primiparous, and 16% had a previous vaginal delivery. The OASI rate in forceps delivery was 6.31% (26/412) and in normal vaginal deliveries 0.8% (29/3272) with an OR of forceps against normal vaginal delivery of 7.53 (95% CI 4.39-12.92; p < 0.0001). 
As seen in table 1, there was a higher rate of major anal sphincter trauma (3c/4th degree tears) in forceps delivery compared to normal vaginal delivery. Episiotomy was performed in 59% of cases, 5% central episiotomy  and 54% mediolateral episiotomy. The accoucher that assisted the delivery was either a training midwife (3/56, 5.4%), midwife (20/56, 35.7%, medical resident (18/53, 32.1%), obstetrician (13/56, 23.2%) or a home birth (2/56, 3.6%). Birthweight over 4kg was found in 7% of these deliveries. Levator ani muscle avulsion was found in 15 patients (27%), however 23% did not show up for their ultrasound scan and 9% were pending to perform their transperineal ultrasound scan at the time of analysis. Avulsion in the forceps group was 38%. Levator hiatus area over 25cm2 was found in 23%, 38% in forceps deliveries and 10% in normal vaginal deliveries. 
Referred patient symptoms at 2 months after delivery were flatal incontinence 5.4% (5/56), fecal incontinence in 3.6% (2/56), urinary incontinence in 5.4% (3/56) and dyspareunia or perineal pain in 16.1% (9/56).
Women at 4 and 6 months were asymptomatic in 83.9 % (47/56), while flatal incontinence persisted in 5.4% (5/56), fecal incontinence in 3.6% (2/56), urinary incontinence in 1.8% (1/56) and dyspareunia or perineal pain in 5.4% (3/56).
Interpretation of results
Risk factors for OASI in our population were forceps delivery and nuliparity which is in concordance with literature.  
Perineal pain and dyspareunia was the major symptom referred by patients at their first follow-up visit which decreased over time. We found a low rate of anal incontinence compared to literature which may be due to the multidisciplinary approach in the care of these women. However, this study is limited due to the sample size and patients lost to follow-up.
Concluding message
Forceps delivery is the main risk factor for anal sphincter injury and was also associated with a higher avulsion rate, increased hiatal area and more severe tears. A considerable ammount of patients were symptomatic on follow-up. These patients should be followed up by multidisciplinary dedicated perineal clinic in order to establish best treatment options and preventable meassures.
Figure 1 Table 1 Anal sphincter tear classification and mode of delivery
  1. Visscher AP, Lam TJ, Hart N, Felt-Bersma RJ. Fecal incontinence, sexual complaints, and anorectal function after third-degree obstetric anal sphincter injury (OASI): 5-year follow-up. Int Urogynecol J (2014) 25:607–613
  2. Royal College of Obstetricans and Gynaecologists. The Management of Third- and Fourth-Degree Perineal Tears. Green-top Guideline No. 29. 2015.
  3. Dietz HP. Pelvic Floor Ultrasound: A Review. Clin Obstet Gynecol. 2017 Mar;60(1):58-81.
Funding NONE Clinical Trial No Subjects Human Ethics not Req'd It is a retrospective study without intervention on the patient, in the context of collecting data from standardized clinical practice. Helsinki Yes Informed Consent Yes