Strain uterography in labour

Area of Science:

• Reproductive Physiology
• Maternal-Fetal Medicine
• Biomechanical Analysis of Labor

Background:

• Understanding the biomechanics of uterine contractions is essential for monitoring labor progression.
• Previous studies have suggested complex patterns of myometrial activity during pregnancy and labor.

Purpose of the Study:

• To investigate the spatiotemporal characteristics of uterine contractions using multi-strain measurements.
• To determine the direction and speed of contractile wave propagation.
• To analyze muscle fiber strain patterns and their relationship to labor progression and uterine dysfunction.

Main Methods:

• Multi-strain measurements were performed on 36 women between 36 and 42 weeks of gestation.
• Analysis focused on identifying dominant pacemaker regions and contractile wave direction and velocity.
• Longitudinal muscle fiber strains were quantified during normal labor.

Main Results:

• A dominant pacemaker area was identified in the fundal region of the uterus.
• Contractile waves propagated downwards at an average speed of 6 cm/second.
• Longitudinal muscle fibers exhibited a transition from extension in the fundus to compression in the lower uterus, with peak contraction intensities of 6% (extension) and -2% (compression).

Conclusions:

• The findings support a model of uterine contraction originating from a dominant fundal pacemaker with downward propagation.
• Quantification of muscle fiber strain, contraction frequency, and myometrial tonus are vital for assessing uterine function and dysfunction during labor.