4. Epidemiology
• Rate of Obstetric Anal Sphincter Injuries (OASIS) in
England has tripled from 1.8% to 5.9% (2000 until 2012)
• Incidence in primiparae is 6.1%, multipara 1.7%
Royal College of Obstetricians and Gynaecologist. A third- or fourth-degree tear during birth:
Information for you. London: RCOG; 2015.
5. Grade 1 : Laceration of vaginal epitel and perineal skin
Grade 2 : Grade 1 rupture + laceration of perineal muscle
Grade 3 : Grade 2 rupture + laceration of anal sphincter
Grade 4 : Grade 3 rupture + laceration of anal mucosa
Old Classification
Perineal Rupture Classification
6. New Classification
1st
Degree
• Injury to perineal skin and/or vaginal
mucosa
2nd
Degree
• Injury to perineum involving perineal
muscles but not involving the anal sphincter
3rd
Degree
• Injury to perineum involving the anal sphincter complex
• 3a: Less than 50% of EAS thickness torn
• 3b: More than 50% of EAS thickness torn
• 3c: Both EAS and IAS torn
4rd
Degree
• Injury to perineum involving the anal
sphincter complex (EAS and IAS) and
anorectal mucosa
Fernando R, Sultan AH, Kettle C, Radley S, Jones P, O’Brien S, 2006, ‘Repair techniques for
obstetric anal sphincter injuries: a randomized trial’, Obstet Gynecol : 107 : 1261-8.
Fernando RJ, Williams AA, Adams EJ. The management of third-and fourth-degree perineal tears. RCOG Green-top
7. How to identificate anal
sphincter injuries?
• Examined systematically by a digital rectal examination
to assess the severity of damage, particularly prior to
suturing
• NICE perineal care guidance:
• Explain to the woman what thay plan to do and why
• Offer inhalational analgesia
• Ensure good lighting
• Position to the woman so that she is comfortable and so that
the genital structures can be seen clearly (lithotomy
position)
Evidence Level 2+
Royal College of Obstetricians and Gynaecologist. A third- or fourth-degree tear during birth:
Information for you. London: RCOG; 2015.
8. How to identificate anal
sphincter injuries?
• Using endoanal ultrasound immediately following
delivery was not significantly increasing the detection
rate of OASIS compared with clinical examination alone.
Evidence Level 3
Royal College of Obstetricians and Gynaecologist. A third- or fourth-degree tear during birth:
Information for you. London: RCOG; 2015.
9. Repair of Anorectal
Mucosa
• The torn anorectal mucosa should be repaired with
sutures using either the continous or interupted
technique.
• When using catgut it was recommended insert
interrupted sutures with the knot tied within the anal canal
(minimise tissue reaction and infection)
• Using polyglactin it was recommended using continous
techniques (it dissolves by hydrolysis)
• Figure if eight sutures should be avoided during repair
anorectal mucosa because they can cause ischemia
Evidence Level 4
D
Royal College of Obstetricians and Gynaecologist. A third- or fourth-degree tear during birth:
Information for you. London: RCOG; 2015.
10. Repair Internal Anal
Sphincter
• Where the torn IAS can be identified, it is advisable to
repair this separetely with interrupted or mattress
sutures without any attempt to overlap the IAS
• Using the end-to-end technique, repairing IAS improves the
likelihood of subsequent anal continence
C
Evidence Level 2+
Royal College of Obstetricians and Gynaecologist. A third- or fourth-degree tear during birth:
Information for you. London: RCOG; 2015.
11. Repair External Anal
Sphincter
• For repair of full thickness EAS tear, either overlapping
or an end-to-end (approximation) method can be used
with equivalent outcomes.
• For partial thickness (all 3a and some 3b) tears, an en-to-
end technique should be used.
A
D
Royal College of Obstetricians and Gynaecologist. A third- or fourth-degree tear during birth:
Information for you. London: RCOG; 2015.
12. End-to-end Approximation of EAS
Sultan AH. Primary repair of obstetric anal sphincter injuries. Cardozo L, Staskin D, et al, editors. In: Textbook of
Female Urology and Gynecology. 3rd ed. London: Informa Healthcare; 2010. p. 863-9
14. Overlap repair of EAS
Sultan AH. Primary repair of obstetric anal sphincter injuries. Cardozo L, Staskin D, et al, editors. In: Textbook of
Female Urology and Gynecology. 3rd ed. London: Informa Healthcare; 2010. p. 863-9
15. Repair External Anal
Sphincter
• No statistically significant difference in perineal pain (RR
0.08,95%CI 0.00-1.45), dyspareunia (RR 0.77, 95%CI
0.48-1.24), flatus incontinence (RR 1.14, 95%CI 0.58-
2.23) between two repair techniques at 12 months.
• It showed statistically significant lower incidence of fecal
urgency (RR 0.12, 95%CI 0.02-0.86), lower anal
incontinence score in the overlap group, lower risk of
deterioration of anal incontinence symptoms over 12
months (RR 0.26, 95%CI, 0.09-0.79)
Evidence Level 4
Royal College of Obstetricians and Gynaecologist. A third- or fourth-degree tear during birth:
Information for you. London: RCOG; 2015.
16. Suture Materials
• 3-0 polyglactin should be used to repair the anorectal
mucosa as it may cause less irrtitation and discomfort
than polydioxanone (PDS) sutures.
• When repair of the EAS and/or IAS muscle is being
performed, either monofilament sutures such as 3-0 PDS
or modern braided sutures such as 2-0 polyglactin can be
used with equivalent outcomes.
D
B
Royal College of Obstetricians and Gynaecologist. A third- or fourth-degree tear during birth:
Information for you. London: RCOG; 2015.
Evidence Level 4
17. Suture Materials
Material Brand Name Manufacture
Polyglactin Vicryl® Ethicon
Polydioxanone PDS® II Ethicon
Polyglycolic acid Safil® B Braun
18. Antibiotics
• The use of broad-spectrum antibiotics is recommended
following repair of OASIS to reduce the risk of
postoperative infections and wound dehiscence.
• A Cochrane review from one randomised controlled trial of
147 participants suggested that prophylactic antibiotics help
to prevent perineal wound complications following third-or
fourth-degree perineal tears, loss to follow-up was very
high.
B
Evidence Level 1-
