1, KMC Quarters, Manipal University Campus, Manipal 576104, India.
Arch Gynecol Obstet. 2011 Mar;283(3):455-9. doi: 10.1007/s00404-010-1384-6. Epub 2010 Feb 10.
To correlate lower uterine segment (LUS) thickness measured by abdominal sonography at term pregnancy with that measured manually using caliper at cesarean delivery and to find out minimum LUS thickness indicative of its integrity in women with previous cesarean.
In 106 women with previous cesarean delivery and 68 with unscarred uterus, abdominal sonographic assessment of LUS was carried out within a week of delivery. Sonographic measurements were correlated with manual measurement of lower flap of LUS using Vernier calipers in 96 of these women (64 with previous cesarean and 32 of unscarred uterus) who had elective cesarean delivery.
Sonographically determined LUS was thinner among women with previous cesarean delivery than in those without (4.58 SD 1.05 vs. 4.8 SD 0.8; t = 1.986; p = 0.04). Women with vaginal birth after cesarean had thicker LUS than women with repeat cesarean delivery (4.4 SD 0.97 vs. 4.48 SD 1.0). The findings were not influenced by engaged fetal head status or amount of bladder fullness. Directly measured LUS thickness using Vernier calipers before delivery of the baby confirmed ultrasound measurements, but showed smaller differences between them. There were eight cases with defective uterine scar at cesarean. LUS thickness at term of 3 mm provided 87.5% sensitivity and specificity, and was found to have negative predictive value of 98%. But in two of seven cases the actual LUS was not measurable despite sonographic measurement of 3 mm, and there were two records of scar dehiscence in those with 3 and 4 mm of LUS thickness.
LUS thickness of 3 mm measured by abdominal ultrasonography prior to delivery at term in women with previous cesarean is suggestive of stronger LUS but is not a reliable safeguard for trial of labor.
在足月妊娠时，通过腹部超声测量子宫下段（LUS）厚度，并与剖宫产时使用游标卡尺手动测量的厚度进行相关性分析，以找出既往剖宫产妇女中提示其完整性的最小 LUS 厚度。
在 106 例既往剖宫产和 68 例无瘢痕子宫的妇女中，在分娩后一周内进行腹部超声评估 LUS。在这 96 例（64 例既往剖宫产，32 例无瘢痕子宫）择期剖宫产的妇女中，使用游标卡尺对 LUS 下叶进行了超声测量与手动测量的相关性分析。
既往剖宫产妇女的 LUS 厚度比无剖宫产史的妇女薄（4.58±1.05 比 4.8±0.8；t=1.986；p=0.04）。阴道分娩后行剖宫产的妇女 LUS 比重复剖宫产的妇女厚（4.4±0.97 比 4.48±1.0）。这些发现不受胎头入盆情况或膀胱充盈程度的影响。在分娩前使用游标卡尺直接测量 LUS 厚度，与超声测量结果一致，但两者之间的差异较小。有 8 例剖宫产时存在子宫瘢痕缺陷。在足月时，LUS 厚度为 3mm 时具有 87.5%的敏感性和特异性，阴性预测值为 98%。但在 7 例中有 2 例尽管超声测量为 3mm，但实际 LUS 不可测量，而在 LUS 厚度为 3 和 4mm 的 2 例中有瘢痕裂开的记录。
在既往剖宫产的妇女中，在足月分娩前通过腹部超声测量的 3mm LUS 厚度提示 LUS 较强，但不能作为试产的可靠保障。
