The role of asymmetric thickening of the uterine myometrium during pregnancy

This study aimed to examine the role of local uterine contractions during pregnancy depicted as asymmetric thickening of the myometrium ultrasonographically.

419 pregnant women at 12–21 weeks of gestation who visited our outpatient department were studied. These subjects visited either for regular antenatal examinations or because of ill-defined subjective symptoms. Ultrasonographic examination was conducted to detect asymmetric thickening of the uterine myometrium. Blood flow in the region of myometrial thickening was studied by color Doppler imaging.

Among 419 subjects, 27.38 % (112/419) patients visited our outpatient department showed asymmetric thickening of myometrium. Since cervical changes or progression to labor occurred in none of the subjects, the reviewed symptoms were considered to be benign contractions. Many women with ill-defined symptoms showed asymmetric thickenings of the myometrium (73.75 % sensitivity and 84.32 % specificity). Myometrial thickening under the placenta tended to be associated with abundant blood flow (88.46 % sensitivity and 87.21 % specificity). This different pattern of the blood flow was considered to correlate to arcuate artery resistance but did not correlate to the severity of ill-defined symptoms. Among those patients having no clinical symptoms, 53 exhibited asymmetric thickening of the myometrium. This phenomenon might be the caution of ill-defined symptoms.

Asymmetric thickening of the uterine myometrium during pregnancy represented the ill-defined symptoms. Different patterns of blood flow images at this local contraction did not correlate to the severity of these symptoms.