Doret Muriel, Bukowski Radek, Longo Monica, Maul Holger, Maner William L, Garfield Robert E, Saade George R
Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas, USA.
Obstet Gynecol. 2005 Apr;105(4):822-30. doi: 10.1097/01.AOG.0000157110.62926.d7.
Differentiating uterine contractions leading to preterm birth from ineffective uterine activity is difficult with current tools. Uterine electromyographic activity is recordable and consists of bursts (group of action potentials) characterized by characteristics that are different during pregnancy and labor. Our aim was to identify the chronology of the changes in uterine pressure and electromyographic characteristics during mifepristone-induced preterm labor in pregnant rats and to determine the earliest characteristic to change.
On day 17 of gestation, intrauterine catheter and electromyography electrodes were implanted in the uterus. On day 18, rats were allocated for treatment with mifepristone or placebo. Intrauterine pressure and electromyography integral activities and electromyography mean were calculated before treatment and 6, 12, 18, 20, 22, and 24 hours after treatment. After mathematical transformation, burst analysis was performed by using power density spectrum energy, peak amplitude, and frequency.
As expected, delivery rate within 24 hours was higher in the mifepristone-treated group. Changes in electromyography integral activity and mean, power density spectrum energy, and intrauterine pressure integral activity occurred late during preterm labor, in a range of 2-4 hours before delivery. Electromyography peak frequency of the power density spectrum exhibited early changes, with a shift from low to high frequencies starting at 12 hours before delivery.
Electromyography peak frequency of the power density spectrum from individual bursts was the first characteristic to change after antiprogestin treatment, preceding any change in intrauterine pressure, making it a potentially useful marker for the early diagnosis of preterm labor.
利用现有工具区分导致早产的子宫收缩与无效子宫活动较为困难。子宫肌电活动是可记录的，由阵发（动作电位群）组成，其特征在妊娠和分娩期间有所不同。我们的目的是确定米非司酮诱导的孕鼠早产期间子宫压力和肌电特征变化的时间顺序，并确定最早发生变化的特征。
在妊娠第17天，将宫内导管和肌电图电极植入子宫。在第18天，将大鼠分为米非司酮治疗组或安慰剂组。在治疗前以及治疗后6、12、18、20、22和24小时计算宫内压力和肌电图积分活动以及肌电图平均值。经过数学变换后，通过使用功率密度谱能量、峰值幅度和频率进行阵发分析。
正如预期的那样，米非司酮治疗组在24小时内的分娩率更高。肌电图积分活动和平均值、功率密度谱能量以及宫内压力积分活动的变化在早产后期出现，即在分娩前2 - 4小时范围内。功率密度谱的肌电图峰值频率出现早期变化，从分娩前12小时开始从低频向高频转变。
单个阵发的功率密度谱的肌电图峰值频率是抗孕激素治疗后第一个发生变化的特征，早于宫内压力的任何变化，使其成为早产早期诊断的潜在有用标志物。
