Amniotic fluid index (AFI) is a quantitative estimate of amniotic fluid and an indicator of fetal well-being.

Values. Amniotic fluid index chart helps evaluate the amniotic fluid levels and baby development. Evaluate amniotic fluid for the presence of RBCs (semiquantitative), WBCs, differential, and for physical appearance Limitations Leukocyte (WBC) count is often of limited value; however, amniotic fluid infection or chorioamnionitis is usually associated with polymorphonuclear leukocytosis (>100/μL). The primary source of elimination is through fetal swallowing, which has been observed as early as 16 weeks. Hughes DS, Magann EF, Whittington JR, et al. REFERENCES: 1. In: Fetus and Neonate — Volume 4: Body fluids and kidney function, Brace, RA, Hanson, MA, Rodeck CH (Eds), Cambridge University Press, 1998. p.88. In 67 normal pregnancies, there was no relationship between HFUPR and amniotic fluid volume measured between 36 and 41 weeks gestation. In 12 patients with fetal growth retardation, a relationship was found between reduced fetal urinary output and low amniotic fluid volume between 36 and 38 weeks gestation. 6 Studies using radiolabeled red blood cells and radioactive colloid estimate that, on average, a fetus swallows from 200 to 450 ml/day at term, removing 50% of the amniotic fluid produced through fetal urination. Brace RA, Wlodek ME, Cock ML, Harding R. Swallowing of lung liquid and amniotic fluid by the ovine fetus under normoxic and hypoxic conditions. Amniotic fluid is eliminated by at least three mechanisms. Another method for assessing the AF, called the Amniotic Fluid Index (AFI), uses the sum of the deepest vertical pocket of fluid found in each quadrant of the uterus the normal range for the AFI is 5 to 25 cm [12,13].Both methods are qualitative measures of the AF and may be a poor reflection of the actual amniotic fluid volume [14].

Magann EF, Perry KG Jr, Chauhan SP, et al. In order to be able to evaluate abnormal amniotic fluid volume in twin pregnancies, normal volume must first be defined. The only study that was embarked upon to address this question, evaluated amniotic fluid volume … J Ultrasound Med 2020; 39:373. Normal amniotic fluid volume in twins. OBJECTIVE: To ascertain if a dye-determined amniotic fluid volume was predictive of intrapartum and perinatal outcome. Amniotic fluid volume regulation. Lind The sum of the four quadrants, in millimeters or centimeters, is amniotic fluid index. Accuracy of the Ultrasound Estimate of the Amniotic Fluid Volume (Amniotic Fluid Index and Single Deepest Pocket) to Identify Actual Low, Normal, and High Amniotic Fluid Volumes as Determined by Quantile Regression.

Usually, the normal value of amniotic fluid index varies from 50 mm to 250 mm (or 5 cm to 25 cm).