Australian and New Zealand Journal of Obstetrics and Gynaecology 2007; 47: 341–344
Short Communication
Blackwell Publishing Asia
Avulsion of the pubovisceral muscle
Avulsion of the pubovisceral muscle associated with large vaginal tear
after normal vaginal delivery at term
Hans Peter DIETZ,1 Alec V. L. GILLESPIE1 and Pramod PHADKE2
1
Department of Obstetrics and Gynaecology, and 2Radiology Department, Nepean Hospital, Penrith, New South Wales, Australia
Abstract
Trauma to the levator ani muscle commonly occurs during vaginal childbirth and is associated with female pelvic
organ prolapse in later life. To date, such trauma was thought to be occult. We present a case of intrapartum diagnosis
of levator avulsion in a patient who suffered a large vaginal tear at the time of a normal vaginal delivery at term.
Key words: avulsion, birth trauma, levator ani, pelvic floor muscle, 3D ultrasound.
Introduction
Recent advances in pelvic floor assessment by clinical
examination and axial plane imaging have led to the
rediscovery of a form of maternal birth trauma which has
intermittently been documented in the literature since 1907
but currently is absent from modern textbooks of obstetrics.
Avulsion of the pubovisceral muscle from the pelvic sidewall
seems to occur in 15–30% of vaginally parous women1,2
and is associated with pelvic organ prolapse, as shown by
the first author and others.2–5
Until recently, it was accepted that trauma to the
pubovisceral muscle, while palpable in the interval and
evident on axial plane imaging, was occult at the time of
delivery and impossible (or at least very difficult) to diagnose
immediately after childbirth. In this case report, we describe
what to our knowledge is the first intrapartum diagnosis of
levator trauma in the world literature.
The patient was approached and asked for her consent to
the publication of a case report, and she gave written consent
which is held by the first author.
Case report
MH, a 23-year-old primigravida, was admitted to delivery
suite at 40+1 weeks after spontaneous onset of labour.
During her pregnancy, she had suffered with hyperemesis
and depression. There were social issues requiring admission
to hospital, but no major pregnancy-related medical
problems. An ultrasound at 34 weeks showed normal growth
with a singleton fetus on the 50th centile.
After admission, she was found to be in established
labour and progressed to a normal vaginal delivery after a
first stage of eight hours and a second stage of one hour and
30 min. She was delivered of a healthy male weighing 3.19 kg
with Apgar scores of 9 and 10, from occipito-anterior
position. Her midwife was in attendance, and the delivery
was not unduly precipitate. The attendants decided against
episiotomy, as is the policy at this unit. However, MH
suffered a large tear that clearly required suturing in theatre.
On exploration in theatre, it was found that the perineum
had a small central second-degree tear, extending into an
extensive vaginal wall tear on the right. The vagina was
detached from the pelvic sidewall (see Fig. 1). The tear
extended along two-thirds of the length of the vagina. The
right labium minus was split longitudinally along its length,
reaching almost to the clitoris. The right pubic ramus was
visible and had been denuded of the overlying musculature,
save for a few muscle fibres still adherent to the most anterior
aspects of the muscle insertion (see Fig. 2). On exploration,
we were able to identify the obturator fascia, and it was
found that the pubovisceral muscle had retracted
pararectally. Further cranially, intact muscle was identified
between the obturator fascia and the anorectal angle.
The fibres of the divided levator musculature were
identified and reattached to the pubic ramus periosteum with
two layers of interrupted Polysorb sutures. The labial tear
was sutured in the normal way with a continuous Polysorb
suture, as was the lateral vaginal tear. Finally, the perineal
tear was repaired in layers with continuous Polysorb.
Correspondence: Associate Professor Hans Peter Dietz,
Department of Obstetrics and Gynaecology, Nepean Clinical
School, University of Sydney, Nepean Hospital, Penrith,
NSW 2750, Australia.
Email: [email protected]
DOI: 10.1111/j.1479-828X.2007.00748.x
Received 12 February 2007; accepted 31 March 2007.
© 2007 The Authors
Journal compilation © 2007 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists
341
H. P. Dietz et al.
Figure 1 Appearances prior to exploration of a large vaginal
tear. The tear extends from close to the clitoris ventrally (upper
arrow) to the fourchette dorsally. The pathognomonic feature of
levator avulsion seems to be separation of the vagina from the
pelvic sidewall, opening up a slit-like space between sidewall and
vagina (lower arrow).
Figure 2 On exploration there are some remaining muscle
fibers visible on the (otherwise denuded) inferior public ramus
(top arrow). Further cranially, intact muscle is detected inserting
on the obturator fascia (middle arrow). The retracted torn
pubovisceral muscle is visible between the surgeon’s hands
(lowermost arrow).
In order to confirm the diagnosis and ascertain the outcome
of the repair described above, we arranged for 4D ultrasound
and magnetic resonance imaging (MRI) follow-up appointments.
fibres. The right lateral edge of the vagina was seen to reach
the lateral pelvic wall contacting the obturator internus
muscle with loss of intervening adipose tissue. These features
are best appreciated when compared with the contralateral
left side (see Fig. 3).
Magnetic resonance imaging
Methodology
Ultrasound
The examination was carried out in supine position using a
phased array body coil on a 1.5 T MRI system (Magnetom
Symphony, Siemens, Erlangen, Germany). High-resolution
T2 weighted turbo spin echo images were obtained using
the following parameters: TR 4410/TE126/ETL 19/BW130/
FOV 226 × 380 and phase resolution of 304 × 512. Axial sections
were obtained with a 5-mm slice thickness and interslice gap
of 1.5 mm. The axial sections were tilted down anteriorly by
13.8 degrees to align with the plane of the pelvic floor.
Methodology
Findings
The axial sections clearly demonstrated attenuation (thinning)
of the levator muscle on the right with a focal defect in its
342
Translabial ultrasound was undertaken after bladder
emptying and in the supine position, as previously
described.1,2 We used a GE Kretz Voluson 730 expert system
(GE Medical Ultrasound, Zipf, Austria) with 8–4 Mhz
volume transducer and an acquisition angle of 85 degrees.
Cine volume datasets were obtained at a temporal resolution
of 1–4 Hz and stored on a hard disk for later analysis.
Post-processing was undertaken using GE Kretz 4D View
version 5.0 on a desktop PC, employing speckle reduction
imaging and multislice or tomographic ultrasound. For
assessment of levator integrity, we used volumes obtained on
maximal pelvic floor muscle contraction as this seems to
© 2007 The Authors
Journal compilation © 2007 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists; 47: 341–344
Avulsion of the pubovisceral muscle
Figure 3 A comparison of 4D pelvic floor
ultrasound (left) and magnetic resonance
(MR) (right) findings as imaged in the
axial plane three months after a normal
vaginal delivery. The MR image represents
a slice of 5-mm thickness in the plane of
minimal dimensions, tilted at 13.8 degrees
in a ventrocaudal to dorsocranial direction.
The ultrasound image represents a
rendered volume of 1.5-cm thickness, at
a depth of 0.5–2 cm above the inferior
symphyseal margin, and tilted at 11
degrees in a ventrocaudal to dorsocranial
direction.
Clinical follow up
Three months after her delivery, MH was seen for a clinical
appointment. She reported significant right-sided pain and
dyspareunia, but both appeared to be settling at the time of
her appointment. There were no symptoms related to
bladder or bowel function, and no symptoms of prolapse.
On clinical examination, there was a first-degree cystocele
and uterine descent, and the clinical stress test was negative.
The levator defect was clearly palpable and appeared to be
typical for a right-sided avulsion injury. There was no
palpatory evidence of the repair attempt.
Figure 4 Tomographic ultrasound imaging of the pubovisceral
muscle three months after normal vaginal delivery, illustrating
the extent of the right-sided avulsion injury (indicated by *). It
measured between 10 and 22 mm in the dorsoventral dimension
and extended through all eight slices, that is, over at least
1.75 cm.
delineate muscle defects most clearly.3 Imaging was performed
at two weeks, two months and three months post-partum,
and findings varied only in minor details.
Findings
There was complete absence of the right insertion of the
pubovisceral muscle on the inferior pubic ramus (see Fig. 3),
with the vagina being in direct apposition to the lateral
pelvic sidewall. The muscle was retracted laterally and
dorsally. The defect measured between 8 and 22 mm in
the anteroposterior dimension and at least 17.5 mm in the
ventrocaudal dimension (see Fig. 4 for a tomographic
representation). Findings were typical of a right-sided
complete avulsion injury of the pubovisceral muscle, with no
evidence of successful repair.
Conclusion
To the knowledge of the authors, this case report is the
first documented instance of intrapartum diagnosis of major
delivery-related levator trauma. Such trauma is common and
seems to constitute the ‘missing link’ (or a substantial part of
this link) between vaginal childbirth and female pelvic organ
prolapse.2,5 As shown in this case report, occasionally such
trauma will be overt, exposed by large vaginal tears. It is
usually a consequence of a first vaginal delivery, more common
in women requiring vaginal operative delivery, and clearly
associated with increasing maternal age at first delivery.6,7
Evidently, most levator tears are occult, which explains
that this form of major maternal birth trauma has largely
escaped attention to date. However, in some instances (such
as the one presented here) such injuries are overt and
provide a unique opportunity for documenting the extent
and nature of the injury, and potentially allowing attempts at
repair. Unfortunately, the particular nature of the trauma,
that is, avulsion of the muscle off its bony insertion, seems
to argue against successful repair by conventional means.
Other methods of repairing such trauma may have to be
developed, necessitating in vitro research into the biomechanical
properties of the interface between inferior pubic ramus and
pubovisceral muscle.
© 2007 The Authors
Journal compilation © 2007 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists; 47: 341–344
343
H. P. Dietz et al.
References
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3 Dietz H. Classifying major delivery-related pelvic floor
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4 DeLancey J. The hidden epidemic of pelvic floor dysfunction:
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5 Margulies R, Huebner M, DeLancey J. Levator ani muscle
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7 Dietz H, Lekskulchai O. Does delayed childbearing increase the risk
of levator injury in labour? Neurourol Urodyn 2006; 25: 509–510.
© 2007 The Authors
Journal compilation © 2007 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists; 47: 341–344