This document discusses a study analyzing the effects of mediolateral (ML) episiotomies on the innervation zones (IZs) of the external anal sphincter (EAS) muscle using a novel non-invasive technique. The study found that ML episiotomies reduced the number of IZs on the side of the incision when assessed pre and postpartum. The technique could help identify the optimal location for ML episiotomies and evaluate muscle innervation before and after surgery or childbirth.

2. L-V
L-DR-D
R-V
D
L
V
R
El.1
El.2
El.3
El.4
El.5
El.6
El.7
El.8El.9
El.10
El.11
El.12
El.13
El.14
El.15
El.16
Definition of Quadrants of the EAS
5 mm
DRP1x16-05-MC

3. Possible sphincter damage due to episiotomy
V
A
Low
risk
V
A
Medium
risk
V
A
High
risk
V
A Very
high
risk

4. L-V
L-DR-D
R-VR-V
Location of episiotomies
(N = 82)

5. 16
12 4
8
V
L R
D
16
12 4
8
V
L R
D
IZ
IZ

6. Pre Partum (Week
34)
Post Partum
(Week 6)
Motor units and Innervation zones

7. IZ distribution – Episiotomies
*
Wilcoxon signed-
rank test; p<0,05
L-V L-D R-D R-V
0
0.5
1
1.5
2
2.5
3
3.5
NumberofIZs
Quadrant
IZ decrease – Pre/Post partum
PRE POST
(N = 82)

8. Conclusions
 The ML episiotomy reduces the number
of innervation zone on the side where the
incision is performed
 A novel technique for non invasive
assessment of the innervation pattern of
the EAS was developed
 It could be used to identify the right
location for a mediolateral episiotomy
and to evaluate muscle innervation pre-
and post-surgery