Chauhan S P, Magann E F, Cowan B D, Perry K G, Morrison J C
Department of Obstetrics and Gynecology, University of Mississippi Medical Center, Jackson 39216-4505, USA.
J Miss State Med Assoc. 1998 Jan;39(1):6-9.
To describe a predictable relationship that relates amniotic fluid index (AFI) to amniotic fluid volume (AFV) and improve the accuracy of AFI to detect true oligohydramnios.
Data from 42 parturients (group I) who underwent measurements of amniotic fluid sonographically (amniotic fluid index) as well as by dye-dilution technique was used to relate AFI to AFV. Subsequently, 22 consecutive women (group II) were used to test the accuracy of the equation to predict true oligohydramnios.
In group II, 11 of 22 patients had true oligohydramnios and the sensitivity, specificity, positive and negative predictive values of AFI < or = 5.0 to detect a confirmed AFV < 500 mL were 0%, 91%, 0%, and 48%, respectively. These values of AFI, when used in conjunction with the equation, improved to 73%, 55%, 62%, 67%, respectively. With AFI and the equation, significantly more patients in group II with true oligohydramnios (8 of 11) could be detected than with using AFI alone (0 of 11; p = 0.002).
AFI is poor predictor of true oligohydramnios. Using the mathematical model, the detection rate of oligohydramnios is significantly improved.
描述羊水指数（AFI）与羊水量（AFV）之间的可预测关系，并提高AFI检测真性羊水过少的准确性。
选取42例接受超声测量羊水（羊水指数）以及染料稀释技术测量羊水的产妇（I组）的数据，用于建立AFI与AFV的关系。随后，选取22例连续的产妇（II组）来检验该方程预测真性羊水过少的准确性。
在II组中，22例患者中有11例存在真性羊水过少，AFI≤5.0检测确诊AFV＜500 mL的敏感性、特异性、阳性预测值和阴性预测值分别为0%、91%、0%和48%。当将这些AFI值与该方程结合使用时，上述指标分别提高到73%、55%、62%和67%。与单独使用AFI相比，使用AFI和该方程能检测出II组中更多存在真性羊水过少的患者（11例中的8例 vs 11例中的0例；p = 0.002）。
AFI对真性羊水过少的预测能力较差。使用该数学模型可显著提高羊水过少的检测率。
