The Effect of Crowning Time on Levator Ani Muscle Avulsion

Recruiting

• Conditions: Levator Ani Avulsion; Labor Delivery; Time of the Crowning of the Fetal Head; Postpartum

• Registration Number: NCT07210788
• Lead Sponsor: Université de Sherbrooke

Brief Summary

Levator ani muscle is one of the main components of perineal muscles and plays a crucial role in urinary continence and pelvic organ support. An avulsion, detachment from its insertion, of this muscle can occur during vaginal birth. It is well known that this major injury can cause many symptoms such as urinary incontinence and pelvic organ prolapses. Some risk factors of this important injury have been identified in the literature, such as the use of forceps. However, to date, no study has evaluated the impact of the crowning of the fetal head during labor on perineal muscles, specifically the levator ani muscle avulsion. Hence, the objectives of this study are to evaluate the association i) the time of the crowning of the fetal head during labor and levator ani muscle avulsion, ii) the time of the crowning of the fetal head and urogynecological symptoms, and iii) use of episiotomy and levator ani muscle avulsion. Postpartum primiparous women will undergo a 4D transperineal ultrasound to evaluate their pelvic muscles and complete questionnaires assessing urogynecological symptoms.

Detailed Description

This is a prospective cohort study evaluating the impact of the crowning time of the fetal head in the second stage of labor on the incidence of levator ani muscle avulsion. Levator ani muscle is hypothesized to avulse during the distension of the pelvic floor muscles, as during a forceps use, and most probably during the crowning of the fetal head. In the study center, the crowning of the fetal head is systematically calculated during labor by nurses and doctors. To eliminate some potential confounding factors, only primiparous women with spontaneous vaginal delivery of a vertex position baby will be recruited in the post-partum period. In order to evaluate the presence of levator ani muscle avulsion, they will be assessed with a 4D transperineal ultrasound by using a standard diagnosis protocol. The delivery hospital file will then be examined to collect potential confounding variables. Prior to data collection, all study participants will give their written informed consent. This study will add more literature to the prevention of the levator ani muscle avulsion and its long-term complications.

Study Timeline

• Study Start: 2024-04-23
• Status Verified: 2025-08
• Study First Submitted: 2025-08-19
• Study First Submitted QC: 2025-09-29
• Last Update Submitted: 2025-09-29
• Study First Posted: 2025-10-07
• Last Update Posted: 2025-10-07
• Primary Completion: 2026-11
• Study Completion: 2027-02-01

Recruitment & Eligibility

• Status: RECRUITING
• Sex: Female
• Target Recruitment: 92

Inclusion Criteria

Primiparous women GxT1 At term: ≥ 37+0 weeks of gestation (included) Spontaneous vaginal delivery (SVD) Cephalic presentation History of miscarriage before 20 weeks or with a fetal weight < 350g

Exclusion Criteria

Contraindications to vaginal delivery Assisted vaginal delivery Age under 18 years Shoulder dystocia Extensive pelvic reconstructive surgery (e.g., bladder exstrophy repair) Term intrauterine fetal demise Twin or multifetal pregnancy

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Primary Outcome Measures

Name	Time	Method
Number of participants with complete and partial unilateral or bilateral avulsion of the levator ani muscles in the post-partum period	In the post-partum period, up to 1 year post-partum	Diagnostic established with standard levator-urethra gap measures assessed with a transperineal 4D ultrasound
Crowning time of the fetal head	The data was obtained from the medical records of each participant during labor.	The time between the crowning of the fetal head and birth is systematically recorded during labor at the study center for all deliveries. Only participants who meet the inclusion criteria are considered for the study.

Secondary Outcome Measures

Name	Time	Method
Rate and type of perineal tears	The data was obtained from the medical records of each participant during labor.	Grade of perineal tear collected in the medical file
Use of episiotomy	The data was obtained from the medical records of each participant during labor.	Type and use of episiotomy collected in the medical file
Incidence and severity of urogynecological symptoms	In the post-partum period, up to 1 year post-partum	Validated questionnaires on urogynecological symptoms: PFDI-46 and ICIQ-IU-SF; PFDI-46 (Pelvic Floor Distress Inventory - 46 Items) Full title: Pelvic Floor Distress Inventory; Structure \& Scoring: It comprises three subscales: 1. UDI (Urinary Distress Inventory): range 0-300; 2. POPDI (Pelvic Organ Prolapse Distress Inventory): range 0-300; 3. CRADI (Colorectal-Anal Distress Inventory): range 0-400 Interpretation: Higher scores indicate worse symptom distress-i.e., a higher burden of pelvic floor symptom; ICIQ-UI-SF (International Consultation on Incontinence Questionnaire - Urinary Incontinence Short Form) Full title: International Consultation on Incontinence Questionnaire - Urinary Incontinence Short Form Scoring: Total score: 0-21 (sum of items 3, 4, and 5; items 1, 2 are demographic, one item is unscored) Interpretation: A higher score indicates greater severity of urinary incontinence and a greater negative impact on quality of life

Trial Locations

Locations (1)

CHUS Fleurimont; 🇨🇦 Sherbrooke, Quebec, Canada