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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
The correlation between the type of operative vaginal delivery (forceps or vacuum) and the rate of levator ani muscle avulsion: clinical trial.
Scientific title
The correlation between the type of operative vaginal delivery (forceps or vacuum) and the rate of levator ani muscle avulsion: clinical trial.
Secondary ID [1] 293133 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Condition category
Condition code
Reproductive Health and Childbirth 304413 304413 0 0
Childbirth and postnatal care

Study type
Description of intervention(s) / exposure
Nulliparous women who were recruited for an initial evaluation from our maternity unit, Hospital Universitario Virgen de Valme. Patients were recruited prior to instrumentation at delivery and those meeting the inclusion criteria, being randomized into the two study groups (vacuum delivery or forceps delivery).

Deliveries completed using vacuum instrumentation were performed by obstetricians with a minimum of five years’ experience in obstetric practice. In terms of analgesia, epidural analgesia was used for intrapartum analgesia. The forceps used for the instrumentation was the forceps of Kielland and the vacuum was a metal vacuum (Bird’s cup 50 mm, 80 kPa) was used to perform fetal extraction. A suction cup was carefully placed over the flexion point, avoiding caput succedaneum, and rapid negative pressure was applied (over 2 min, until 0.6–0.8 kg/cm2 ). Traction was carried out during contraction, along with maternal push, at a rate of 2–3 tractions per contraction, and without associating Kristeller maneuver. The procedure was abandoned if, after three cup slides or 15 min, fetal extraction had not been successful. Selective episiotomy was carried out in VD following Valme’s University Hospital clinical practice guideline for instrumental deliveries.

Obstetric parameters evaluated were: gestational age, labor induction, epidural analgesia, type of instrumentation, duration of second stage of labor, episiotomy and perineal tears. Fetal parameters studied after birth were: fetal sex, weight, head circumference, umbilical artery pH at birth, Apgar test result (at 1 and 5 min), presence of neonatal morbidity (cephalohaematoma, brachial plexus palsy, etc.), admission to neonatology department and neonatal mortality.

The sonographic evaluation was performed six months after delivery and was carried out by a single examiner, with more than five years experience exclusively in obstetric ultrasound, with specific training in 3/4D imaging and blinded to obstetric data relating to the delivery. A 500_ Toshiba Aplio (Toshiba Medical Systems Corp., Tokyo, Japan) ultrasound with an abdominal probe PVT-675MV 3D was used for the assessments. Images were acquired with patients in dorsal lithotomy position, placed on the gynecological examination table and under empty bladder conditions. The transducer was carefully placed on each patient’s perineum, applying the minimal possible pressure. Three volume measurements were taken for each patient: at rest, with Valsalva maneuver and with maximum contraction. Then, offline analysis of ultrasound volumes was carried out. Analysis of ultrasound volumes was performed offline.

In the multi-view ultrasound images, complete avulsion was defined as an abnormal insertion of LAM in the lower pubic branch identified in all three central slices, i.e. in the plane of minimal hiatal dimensions (PMD) and the 2.5 and 5.0mm slices cranial to this one. Levator hiatus measurements, transverse diameters, anteroposterior diameters and area were also determined in the same plane (PMD).
Intervention code [1] 299383 0
Diagnosis / Prognosis
Comparator / control treatment
Comparator = forceps delivery
Control group

Primary outcome [1] 303652 0
To compare the rate of levator ani muscle avulsion in vacuum delivery versus the rate of the ate of levator ani muscle avulsion in forceps delivery.
The avulsion is studied by 3D transperineal ultrasound, through the multiplanar study, including images at 2.5 mm from the plane of minimal dmensions. Avulsion was defined as the discontinuity of levator ani muscle fibres at their pubic insertion, which were identified in the three central slices of the multiplanar assessment.
Timepoint [1] 303652 0
at 6 months after randomisation
Secondary outcome [1] 339755 0
To compare the levator ani muscle hiatus area (cm2) in vacuum delivery versus the levator ani muscle hiatus area (cm2) in forceps delivery.
Levator hiatal dimensions can be determined on 3D ultrasound by identifying the plane of minimal dimensions, i.e., the plane which contains the minimal distance between the posterior symphyseal margin and the anterior margin of the levator ani loop immediately posterior to the anorectal angle
Timepoint [1] 339755 0
at 6 months after randomisation

Key inclusion criteria
• Delivery with forceps or vacuum
• Cephalic presentation
• Primiparity
• At term gestation (37-42 weeks)
• No prior pelvic floor corrective surgery
• Written informed consent
Minimum age
18 Years
Maximum age
No limit
Can healthy volunteers participate?
Key exclusion criteria
Pregnancies with severe maternal or fetal pathology

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation is not concealed
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table from a statistic book
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

The people assessing the outcomes
Intervention assignment
Other design features
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 9291 0
State/province [1] 9291 0

Funding & Sponsors
Funding source category [1] 297759 0
Name [1] 297759 0
Valme University Hospital
Address [1] 297759 0
Department of Obstetrics and Gynaecology Valme University Hospital, Seville, Spain.
Avda. Bellavista s/n C.P.41014
Country [1] 297759 0
Primary sponsor type
José Antonio García Mejido
Department of Obstetrics and Gynaecology Valme University Hospital, Seville, Spain.
Avda. Bellavista s/n C.P.41014
Secondary sponsor category [1] 296797 0
Name [1] 296797 0
Address [1] 296797 0
Country [1] 296797 0

Ethics approval
Ethics application status
Ethics committee name [1] 298822 0
Andalucia’s Board of Biomedicine Ethics Committee
Ethics committee address [1] 298822 0
Ethics committee country [1] 298822 0
Date submitted for ethics approval [1] 298822 0
Approval date [1] 298822 0
Ethics approval number [1] 298822 0

Brief summary
Our main target is to determine levator ani muscle avulsion rate in vacuum delivery, comparing it to forceps delivery. As secondary goals, we aim to evaluate the difference in levator hiatus area among our study groups, as well as analyze the impact of obstetric and intrapartum risk factors which have previously been described to be associated with levator ani muscle injuries.
Trial website
Trial related presentations / publications
Public notes
Attachments [1] 2118 2118 0 0

Principal investigator
Name 78342 0
Dr José Antonio García Mejido
Address 78342 0
Hospital Universitario de Valme/Avenida Bellavista sn /Sevilla/C.P. 41014/Andalucia/España
Country 78342 0
Phone 78342 0
+34 95 501 53 85
Fax 78342 0
Email 78342 0
Contact person for public queries
Name 78343 0
Dr José Antonio García Mejido
Address 78343 0
Hospital Universitario de Valme/Avenida Bellavista sn /Sevilla/C.P. 41014/Andalucia/España
Country 78343 0
Phone 78343 0
+34 95 501 53 85
Fax 78343 0
Email 78343 0
Contact person for scientific queries
Name 78344 0
Dr José Antonio García Mejido
Address 78344 0
Hospital Universitario de Valme/Avenida Bellavista sn /Sevilla/C.P. 41014/Andalucia/España
Country 78344 0
Phone 78344 0
+34 95 501 53 85
Fax 78344 0
Email 78344 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary