What is the minimum thickness of a scarred uterus that poses a risk?
Aug 06, 2025
Source: Cainiu Health
Dr. Liu Wenmin
Introduction
A scarred uterus refers to a uterus with scars. There is no established minimum thickness of the scarred uterus that defines danger. Generally, a myometrial thickness less than 2 mm in the lower uterine segment is considered risky. Pregnant women with a scarred uterus require enhanced monitoring in the late stages of pregnancy. If the myometrial thickness is found to be less than 2 mm or is accompanied by scar abnormalities, early hospitalization for evaluation is recommended, and pregnancy may need to be terminated promptly when necessary, to reduce the risk of uterine rupture and ensure maternal and fetal safety.
Generally, a scarred uterus refers to a uterus with a scar or cicatrix. There is no established minimum thickness of the scarred uterus that indicates danger. However, it is generally considered risky when the thickness of the lower uterine segment muscle layer is less than 2 mm. Detailed analysis is as follows:
This is because the scar tissue has poor elasticity, and if the muscle layer is too thin, it may not withstand the tension of the uterus during late pregnancy. Especially after the onset of contractions, there is a high risk of scar rupture, which can lead to severe complications such as massive hemorrhage and fetal distress.
In clinical practice, ultrasound monitoring of the thickness of the lower uterine segment muscle layer is used to assess the risk. Regular examinations are especially important during late pregnancy, particularly after 36 weeks. However, thickness alone is not the sole criterion for risk assessment. If the muscle layer at the scar site shows uneven echogenicity or defects, there may still be a high risk even if the thickness is greater than 2 mm.
Pregnant women with a scarred uterus should undergo enhanced monitoring during late pregnancy. If the muscle layer thickness is found to be less than 2 mm or if scar abnormalities are detected, early hospital admission for evaluation is recommended, and pregnancy should be terminated promptly when necessary to reduce the risk of uterine rupture and ensure maternal and fetal safety.
