OASIS repair

Question 1

What type of suture should be used to repair anal epithelium?

Answer 1

3-0 polyglactin

Question 2

Which suture and repair pattern should be used to repair the anal sphincter?

Answer 2

-Repair with 3-0 polydioxanone/PDS or 2-0 polygalactin using an interrupted or mattress repair.
——PDS preferred bcuz PDS retains tensile strength for a longer time than polygalactin
——-Polygalactin loses 60% of tensile strength by 20 days vs polydioxanone has 50% of tensile strength at 5-6wks

Question 3

How is the internal anal sphincter differentiated from the external anal sphincter?

Answer 3

EAS - more superficial, light pink (raw fish) colour
IAS - beefy red

Question 4

How is a full vs partial thickness EAS tear repaired?

Answer 4

After identifying the light pink tissue and grasping the ends with Allis forceps (as the ends tend to retract laterally and inferiorly):

Full thickness: end to end or overlapping repair have similar outcomes; technique depends on surgeon preference.

Partial thickness: end to end repair
- overlapping may put undo strain on the repair (RCOG)

The fascia should be repaired also.
Repair the EAS separate from the IAS.

Question 5

How is an IAS tear repaired?

Answer 5

End to end repair using 3-0 polydioxanone or 2-0 polygalactin suture in an interrupted or mattress suture.

Repair SEPARATELY from the EAS as it increases the chances of anal continence (i.e. reduces anal incontinence)