Obstetric Anal Sphincter Injury (OASI) has a major burden on patients quality of life due to its important associated symptoms.  Even in patients correctly diagnosed intrapartum and adequate repair, 40% will refer anal incontinence (1).  These patients require follow-up in search for possible pelvic floor dysfunction and early intervention (2). The primary aim of the current study was to determine which factors are more frequent among patients with an obstetrical anal sphincter injury (OASI)  that are referred for rehabilitation.

This was a retrospective observational study which included women with an obstetrical anal sphincter injury that were assessed at a single center during January 2015 and December 2017.  All women sustaining an obstetrical anal sphincter injury at the author’s institution were followed up at 3 to 4 months postpartum by a multidisciplinary team formed by a urogynaecologist, two rehabilitation specialists and a specialized nurse in urogynaecology.  Patients were followed up by either rehabilitation specialist depending on the referral area they were assigned to.  The patients of this study are only those seen by one of the rehabilitation specialist. All patients underwent a urogynaecological history, a clinical examination and a 4D translabial ultrasound (TLUS). All women were administered questionnaires validated in their local language to assess urinary and anal incontinence (Incontinence Severity Index (ISI) and Wexner incontinence scale. The ISI consists of two questions, leakage frequency and amount and classifies patients based on a score from 0 to 12 (complete incontinence). The Wexner incontinence scale assesses anal incontinence with five questions and provides a score on anal incontinence severity that ranges from 0 to 20 (complete incontinence).
TLUS was performed in dorsal lithotomy and after voiding, using Voluson 730 Expert (GE Kretz Medical Ultrasound, Zipf, Austria). Patients were asked to perform an effective Valsalva of at least 6 s and a maximum pelvic floor muscle contraction. Patients were coached to avoid co-activation. Anal sphincter imaging was performed rotating the probe 90 degrees towards the coronal plane. 4D volumes were obtained and analyzed on maximum pelvic floor muscle contraction as previously described. Significant anal sphincter defect was considered when at least 4 out 6 slices was present. (3)
Decision to refer a patient for rehabilitation was established by the multidisciplinary team based on patient symptoms and clinical findings. Data was collected from local electronic database. Variables recorded were age, parity, mode of delivery, birthweight above 4kg, classified perineal tear, body mass index, gestational age at delivery, length of the second stage of labour, repair technique, birthweight, head circumference, ISI score, Wexner score, fecal urgency, fecal urgency warning time, rehabilitation, and episiotomy type if performed. 
Statistical analysis was performed using t-student test for continuous variables and fisher-exact test for binary variables. Statistical significance was considered with a p<0.05

During the inclusion period a total of 77 women were seen at the perineal clinic with the multidisciplinary team with the cited rehabilitation specialist. Their mean age at delivery was 32 years (SD 5, 19-45). 85.5% (65/76) were primiparous. 37.5% (30/73) were obese. Mean completed gestational weeks at delivery was 39. Urinary incontinence was referred in 23.7% (18/76) of patients and anal incontinence in 15.8%(12/76).  Rehabilitation was prescribed in 27.6% (21/76) of patients. 
No associations were found between rehabilitation and obstetrical data (see table 1), length of second stage of labour, forceps delivery, major perineal tears, obesity, parity, episiotomy, repair techinique, birthweight more than 4kg. Rehabilitation was more frequent in patients with urinary incontinence and with significant anal sphincter defects and its length on ultrasound (see table 2). No associations with other ultrasound findings were found such as avulsion, levator hiatal area and bladder neck descent nor with other patient symptoms such as anal incontinence, fecal urgency, fecal urgency warning time, the Wexner score and the ISI score.

We found in our population study, that patients which have sustained an OASI on short term follow-up have frequently anorectal and urinary symptoms despite correct intrapartum diagnosis and primary repair. First line treatment usually consist in lifestyle changes and rehabilitation. Rehabilitation was required in over a quarter of patients. Those factors that seem to influence rehabilitation are urinary incontinence and the extent of anal sphincter defects on univariate analysis. This data must be interpreted with caution, since it may well be the combined findings that may warrant a patient to receive rehabilitation.

The association of urinary incontinence and the extent of anal sphincter defects are important findings in patients that will require rehabilitation. Signicant anal sphincter defects on ultrasound is associated with the need of a patient with OASI to undergo rehabilitation with an OR of 5.13 (CI 1.52-17.31, p=0.006). Ultrasound should be performed in the workup of these patients by a multidisciplinary dedicated team .

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
Royal College of Obstetricans and Gynaecologists. The Management of Third- and Fourth-Degree Perineal Tears. Green-top Guideline No. 29. 2015.
Dietz HP. Pelvic Floor Ultrasound: A Review. Clin Obstet Gynecol. 2017 Mar;60(1):58-81.