Cesarean Scar Thickness Decreases during Pregnancy: A Prospective Longitudinal Study

Area of Science:

• Obstetrics and Gynecology
• Reproductive Medicine
• Medical Imaging

Background:

• Cesarean delivery is a common surgical procedure.
• Uterine scar integrity after cesarean delivery is crucial for subsequent pregnancies.
• The presence of a niche (defect) in the cesarean scar may impact uterine physiology.

Purpose of the Study:

• To longitudinally evaluate changes in uterine scar thickness after cesarean delivery during pregnancy.
• To correlate first-trimester cesarean section (CS) scar myometrial thickness in women with and without a scar niche with low uterine segment (LUS) myometrial thickness changes between the second and third trimesters.

Main Methods:

• Prospective longitudinal study involving pregnant women (18-41 years) with at least one prior CS.
• Transvaginal sonography (TVS) used to assess uterine scars at 11-14 weeks gestation.
• Measurement of scar myometrial thickness, identification of niches, and assessment of LUS myometrial thickness at 18-20 and 32-35 weeks gestation.

Main Results:

• A CS scar niche was observed in 40.2% of participants.
• Uterine scar myometrial thickness significantly decreased from the first to the third trimester (p=0.001).
• Women with a CS scar niche had thinner first-trimester scar thickness and a significantly greater decrease in LUS myometrial thickness between the second and third trimesters compared to the non-niche group (p=0.015).

Conclusions:

• Cesarean section scar myometrial thickness undergoes significant changes throughout pregnancy.
• The presence of a CS scar niche is associated with more pronounced thinning of the low uterine segment myometrium in later pregnancy.
• These findings highlight the importance of evaluating CS scar characteristics for understanding uterine changes during pregnancy.