An observational study to investigate the puborectalis muscle by ultrasound in pregnancy and after delivery

The pelvic floor plays an important role in supporting pelvic organs in women
thereby preventing symptoms like urinary or fecal incontinence and pelvic organ
prolapse. This association is well-known. Less attention has been paid to the
role of the pelvic floor in pregnancy, during childbirth and after delivery.
During pregnancy the pelvic floor will have to resist progressive forces on one
hand, but on the other hand has to adapt to allow maximum dilatation during
delivery. How this adaptation process works over time has hardly been studied.
During engagement and passage of the fetal head at the time of delivery the
pelvic floor muscles are stretched and compressed against the pelvic sidewall.
This will induce injuries. Only one recent study (van Delft) looked at the
ultrasound image of the puborectal muscle 3 days after delivery and noticed the
occurrence of hematomas and abruptions of the muscle from its attachment at the
pubic bone. After vaginal delivery recovery of the pelvic floor muscles starts,
but this process has not been studied in itself or compared to recovery after
caesarean section.
The pelvic floor consists of striated muscles and connective tissue
(part loose and part condensed into ligaments). Not only the pelvic floor
undergoes changes, but also the uterus, cervix and other pelvic structures must
adapt to facilitate delivery. With three-dimensional (3D) ultrasound scans, it
is possible to visualize the pelvic floor muscles, particularly the puborectal
part of the levator ani. A new ultrasound parameter to assess muscle integrity
and composition is echogenicity. In a cohort study of primigravid women at the
UMCU a technique to study the mean echogenicity of the puborectalis muscle
(MEP) was developed in collaboration with the Technical Medicine Department of
the University of Twente. This mean echogenicity of the puborectalis muscle was
studied, amongst others, in relationship to pregnancy outcome. Our initial
results strongly suggest that there is an association between echogenicity of
the puborectalis muscle at 12 weeks gestation and mode of delivery. In other
words, the MEP at 12 weeks gestation could serve as an important predictor for
a Caesarean section due to failure to progress. It is unclear if this
difference in echogenicity is locally confined to the puborectal muscle or
constitutional.

1. Our finding that measuring MEP at 12 weeks gestation could be an important
marker for normal or abnormal delivery which needs to be confirmed in a
separate study.
2. To measure the echogenicity of the uterus (myometrium), cervix and vastus
lateralis muscle at 12 weeks gestation in association with mode of delivery
3. The process of normal regeneration after vaginal delivery needs to be
studied. Ultrasound is easy to use, cheap and repeatable. This information on
normal recovery is crucial for our regenerative medicine program. In the latter
we focus on techniques to enhance regeneration after delivery in order to
minimize permanent damage. Using echogenicity as a marker is promising, but
needs to be studied.

Prospective cohort study.

All women participating will receive their regular prenatal and postnatal care.
The burden associated with participation is an extra ultrasound of the pelvic
floor which will be scheduled during a routine visit if possible (range 8-14
weeks). The pre-selected group will have 8 extra ultrasounds. 20 patients
getting a primary caesarean section, will undergo 3 ultrasound examinations (1
before and 2 after delivery). Accidental findings will be reported.