CArE for OAsI Study: Care Pathways and Anorectal Evaluation for OASI Associated Incontinence

Historically, pregnancy and childbirth has been erroneously considered to be an innocuous physiological event. However, vaginal delivery may be associated with perineal injury, a common occurrence affecting up to 80% of women. Perineal injury is classified into four categories, as per the Sultan classification:

Grade 1: involvement of perineal skin +/- vaginal mucosa Grade 2: involvement of perineal muscles Grade 3a: <50% External Anal Sphincter (EAS) Grade 3b: >50% EAS Grade 3c: EAS + Internal Anal Sphincter (IAS) Grade 4: Grade 3c + anorectal mucosa The latter two categories are associated with considerable morbidity and are known as obstetric anal sphincter injuries (OASIS). OASIS encompass grade 3 and 4 perineal tears and effect the integrity of the anorectal sphincter complex, with or without involvement of the anorectal mucosa.

Such injuries may be associated with a myriad of devastating and stigmatizing sequelae, including faecal and urinary incontinence, dyspareunia, rectovaginal fistulae, perineal pain and pelvic organ prolapse, which in turn may have a negative impact on a woman's quality of life and day-to-day living. Indeed, sustaining an Obstetric Anal Sphincter Injury (OASI) has been associated with both physical and psychological sequelae.

Symptoms of urgency and urge faecal incontinence, are suggestive of damage to the external anal sphincter, while symptoms of passive leakage are indicative of damage to the internal anal sphincter. Not all women with OASIS are symptomatic. Symptomatic OASIS occurs in about 30-50% of women. It is important to note that the real incidence may be higher as it may very well be underreported.

The incidence of OASIS in the UK is 2.9%. Although OASIS is uncommon, the rate of OASIS in singleton, cephalic and first vaginal deliveries, has reportedly tripled from 1.8% to 5.9% from 2000 to 2012. This may, however, be secondary to better detection of these injuries following improvements in education, training and the utilization of a standardized classification system for perineal tears. To address the rising OASI rates, the OASI care bundle was introduced which primarily focused on interventions in the antenatal period to reduce the incidence of OASIS. Prevention of OASIS, however, will not always be possible, even with the best efforts of care. Therefore, focus should also be placed on the optimal management of these patients' post-partum.

The RCOG (royal college of obstetricians and gynaecologists) guidance states that clinicians should diagnose an OASI at the time of delivery by meticulous inspection of the perineum, which should include a digital rectal examination. Referral to a colorectal specialist should be considered in those who are symptomatic of incontinence. However, in the absence of a standardised national pathway, the provision of healthcare appears to rely heavily on the availability of resources, a clinician's discretion and ultimately a 'postcode lottery'. Indeed, while some trusts may have the necessary provisions in place to support mothers with OASIS, in other areas, women may be left to fend for themselves.

Moreover, the stigma and shame associated with sustaining such an injury may perpetuate the difficulty in seeking medical attention, even in the most motivated patients, thereby producing a population of silent sufferers, who are stuck in a pervasive pattern of shame, embarrassment and inevitably, melancholy.

There may also be the erroneous belief among healthcare professionals, that these symptoms would settle on their own and this may be communicated to the afflicted individual who may be reassured by this information. Although 60-80% of women are asymptomatic at one year, some remain symptomatic, with devastating consequences on their quality of life. Further, patients with an asymptomatic injury ought to be counselled regarding the risk of incontinence in later life, secondary to advancing age and hormonal influence on pelvic floor function as well as the added impact of future deliveries. When discussing mode of delivery for future pregnancies, it should be highlighted that although an elective caesarean section may protect against an anal sphincter injury, it may not prevent pudendal neuropathy which may also contribute to symptoms of incontinence.