History-Dependent Deformations of Rat Vaginas under Inflation

Area of Science:

• Biomedical Engineering
• Reproductive Biology
• Materials Science

Background:

• The vagina is a complex organ with critical mechanical functions in reproduction.
• Its mechanical properties, including deformation under sustained pressure (creep), are not fully understood.
• Understanding vaginal mechanics is vital for reproductive health and disease research.

Purpose of the Study:

• To quantify the creep properties of the vagina ex vivo.
• To investigate vaginal deformation under varying constant pressures in longitudinal and circumferential directions.
• To utilize the rat as an animal model for studying vaginal biomechanics.

Main Methods:

• Ex vivo inflation testing of rat vaginas.
• Application of three consecutively increasing constant luminal pressures (28 kPa, 55 kPa, 83 kPa).
• Measurement of inhomogeneous deformations using digital image correlation (DIC).

Main Results:

• The vagina deformed significantly more in the circumferential direction (CD) than the longitudinal direction (LD) under constant pressure.
• Creep (change in deformation over time) was highest during the initial inflation test at 28 kPa.
• Subsequent inflation tests at higher pressures (55 kPa and 83 kPa) showed reduced creep.

Conclusions:

• The vagina primarily adapts to pressure by altering its diameter (circumferential deformation) rather than length (longitudinal deformation).
• Vaginal creep is pressure-dependent and diminishes with repeated pressure applications.
• These findings enhance understanding of vaginal biomechanics and its role in reproductive physiology and pathophysiology.