12) Postnatal Care - Obstetric anal sphincter injury and consent guidance

Question 1

Overall incidence of OASI

Answer 1

2.9%

Question 2

Incidence of OASI in primiparous women

Answer 2

6.1%

Question 3

Incidence of OASI in multiparous women

Answer 3

1.7%

Question 4

What percentage of women giving birth vaginally will tear to some degree?

Answer 4

90%

Question 5

Classification of perineal trauma

Answer 5

1st: Perineal skin or vaginal mucosa
2nd: Perineal muscles
3A: <50% EAS
3B: >50% EAS
3C: IAS
4: EAS, IAS, anorectal mucosa

Rectal buttonhole tear: Anorectal mucosa but not EAS/IAS.

Question 6

Risk factors for OASI

Answer 6

Asian
Nulliparous
EFW >4kg
Shoulder dystopia
OP position
Prolonged 2nd stage
Instrumental delivery

Question 7

Things to prevent OASI

Answer 7

RML episiotomy with instrumental deliveries
Perineal massage antenatal
Warm compress during second stage
Hands on approach to delivery

Question 8

How to repair OASI?

Answer 8

Anorectal mucosa: Vicryl 3-0. Continuous or interrupted.

IAS: Vicryl 2-0 or PDS 3-0. Interrupted or mattress sutures. End-to-end.

EAS: Vicryl 2-0 or PDS 3-0. Full thickness: Overlapping or end-to-end. Partial thickness: End-to-end.

Question 9

Type of suture PDS and Vicryl

Answer 9

PDS monofilament.

Vicryl braided.

Question 10

Rate of suture migration

Answer 10

7%

Question 11

Post-op care

Answer 11

Antibiotics
Stool softener
Physiotherapy
Follow up 6-12 weeks

Question 12

What percentage of OASI repairs are asymptomatic at 12 months?

Answer 12

60-80%

Question 13

Recurrence rate for OASI

Answer 13

5-7%

Question 14

Risk of worsening faecal symptoms after subsequent vaginal delivery

Answer 14

17% (mostly in women who were initially symptomatic but symptoms resolved by 6m PP)

Question 15

When to consider ELCS?

Answer 15

Symptomatic or abnormal anal manometry or abnormal endoanal USS.

Question 16

Percentage of women choosing ELCS after an OASI in first delivery

Answer 16

25%

Question 17

Risk of faecal urgency

Answer 17

26%

Question 18

Risk of perineal pain/dyspareunia

Answer 18

9%

Question 19

Risk of wound infection

Answer 19

8%

Question 20

Which risks of OASI repair are common?

Answer 20

Incontinence faeces/flatus .
Urgency faeces/flatus
Difficulty opening bowels initially.
Wound infection.
Urine infection.
Pain/dyspareunia.
Suture removal required.

Question 21

Which risks of OASI repair are uncommon?

Answer 21

Recommendation to deliver by CS in future.

Question 22

Which risks of OASI repair are rare?

Answer 22

Haematoma

Failure of repair

Question 23

Which risks of OASI repair are very rare?

Answer 23

Fistula formation