What is the normal range for the amniotic fluid index?

The normal range for the amniotic fluid index (AFI) is 5 to 18 cm. The AFI is calculated by measuring the vertical depth of the largest pocket of amniotic fluid in each of four quadrants—upper left abdomen, lower left abdomen, upper right abdomen, and lower right abdomen—with the umbilicus serving as the central reference point. An AFI below 5 cm generally indicates oligohydramnios (low amniotic fluid), whereas an AFI above 18 cm suggests polyhydramnios (excessive amniotic fluid). Both oligohydramnios and polyhydramnios are considered abnormal conditions requiring clinical attention. Prompt medical evaluation is essential to identify the underlying cause, and management should be carried out under the guidance of a healthcare provider.