Running Title
Ultrasound study of pelvic floor in pregnant women
Dear Editor,
Many thanks to Dr Aly Youssef for raising the need for standardising
terminology in the ultrasound study of the pelvic floor in pregnant
women. We agree standardisation is urgently required as the interest in
investigating pelvic floor relaxation and distensibility in pregnant
women and its association with birth outcomes grows. Using conflicting
terminology to describe a pelvic floor contraction that is inappropriate
for the task of bearing down is, as Dr Youssef suggests, confusing for
the audience. We appreciate the description made by Youssef et al.,(1)
and the study referenced, however we think there are multiple issues
with using the terminology levator co-activation. Levator Ani Muscle
(LAM) co-activation is a positive term used to describe the normal
levator ani co-activation with other postural muscles such as
transversus abdominus and the diaphragm in response to normal movement
and breathing (2). Using LAM co-activation in the context of an abnormal
response is itself confusing, particularly when the levator ani muscles
are not co-activating with any other muscle.
Secondly a LAM contraction is an appropriate response to increasing
intra-abdominal pressure, as occurs in the Valsalva manoeuvre (3). We
understand the use of Valsalva in many studies is in fact the bearing
down manoeuvre (BDM), which is where, the fundamental problem lies. In
our study Murdoch-Ward et al., (4) we chose to use the language
paradoxical LAM contraction, since it describes an inappropriate motor
pattern of the LAM during the BDM. We would be interested in further
conversation to come to an agreement on best terminology to use here.
We appreciate the concern with introducing the 2mm cut off for defining
inappropriate LAM activation during the BDM using transperineal real
time ultrasound (TPUS). In our study since we did not use absolute
values of the anterior posterior diameter (APD), we felt capturing an
absolute zero to define no movement would be possibly erroneous and thus
possibly confound our results. We therefore decided to define no
movement with some range for error. Clinicians are using TPUS to measure
APD in pregnant women to analyse the response of the LAM to the BDM
thanks to the work of many researchers including Dr Youssef and his team
(1). According the inter rater reliably study by Bernard et al.(5) there
is a standard error measurement between raters of 1.5mm, suggesting we
should consider standardising an error measurement for the use for the
APD clinically in pregnant women. Once again, we would be happy to
participate in a discussion on standardising the use of TPUS, in
particular the APD measure in pregnant women, to ensure discussion
between researchers and clinicians is transferrable and accurate.
Many thanks is once again extended to Dr Youssef for the feedback, we
very much look forward to reading future research by Dr Youssef and his
team and collaborating on standardising terminology.
Youssef A, Montaguti E, Dodaro M.G, Kamel R, Rizzo N, Bianchini L, Pilu
G. Leavtor ani muscle coactivation at term is associated with longer
second stage of labour in nulliparous women. Ultrasound Obstetrica
Gynecol. 2019;53: 686-692 https://doi.org/10.1002/uog.20159
Sapsford RR, Hodges PW, Richardson CA, Cooper DH, Markwell SJ, Jull GA
(2001) Co-activation of the abdominal and pelvic floor muscles during
voluntary exercises. Neurourol Urodyn 20:31–42
3. El-Hamansy D, Watson A, Corden J, Smith ARB, Reid FM. An assessment
of techniques and practices used to elevate intra-abdominal pressure
when assessing pelvic floor dysfunction. Neurourol Urodyn.
2021;40(3):783-790. doi: 10.1002/nau.24617.
4. Murdoch-Ward J, Nahon I, De-Vitry Smith S, Bernardi E, Woods T.
Assessment of the bearing-down manoeuvre in pregnancy and detection of
paradoxical levator ani muscle contraction using 2D transperineal
ultrasound and vaginal palpation: a concurrent validity and inter-rater
reliability study. BJOG 2023
5. Bernard S, Frenette AG, McLean L, Noël P, Froment MA, Hébert LJ,
Moffet H. Reliability of ultrasound imaging of pelvic floor morphology
and function among females who have undergone pelvic radiotherapy.
Neurourol Urodyn. 2021;40(4):1001-1010. doi: 10.1002/nau.24656.