Amnioinfusion is a method in which isotonic fluid is instilled into the uterine cavity. It was introduced in the 1960s as a means of terminating pregnancy and inducing labor in intrauterine death, but is currently used as a treatment in order to correct fetal heart rate changes caused by umbilical cord compression, indicated by variable decelerations seen on fetal heart rate monitoring. In severe cases of oligohydramnios, amnioinfusion may be performed prophylactically to prevent umbilical cord compression. It has also been used to reduce the risk of meconium aspiration syndrome, though evidence of benefit is mixed. The UK National Institute of Health and Clinical Excellence (NICE) Guidelines recommend against the use of amnioinfusion in women with meconium stained amniotic fluid (MSAF). Uses Diagnostic uses Diagnostic uses for amnioinfusion are limited to pregnancies complicated by oligohydramnios. Infusion of saline can allow for better visualization of fetal structures on ultrasound when there is minimal amniotic fluid. Most often, it is used to increase the sensitivity of detecting anomalies with the fetus's urogenital tract that could be contributing to the oligohydramnios. Often amnioinfusion isn't needed, as renal agenesis, one of the most common causes of oligohydramnios, is detectable through Doppler ultrasound. Therapeutic uses Amnioinfusion is used much more therapeutically in the period just before birth: Oligohydramnios and anhydramnios (lack of amniotic fluid): amnioinfusion can be used in this setting to prevent pulmonary hypoplasia, which is underdevelopment of the fetal lungs. By increasing the amniotic fluid level, the lungs are inflated, leading to normal growth. Oligohydramnios can also lead to compression deformities, which are caused by the pressure of the uterus on the developing fetus. By decreasing pressure on the developing fetus, amnioinfusion increases space for fetal movement and growth. Variable decelerations on fetal heart rate monitoring: These kinds of decelerations in fetal heart rate are caused by umbilical cord compression. This causes risk by decreasing blood flow to the fetus. Amnioinfusion is used as a second-line treatment for these decelerations. By increasing the amount of fluid in the uterus, the umbilical cord will experience less compression. This is usually combined with maternal hydration and repositioning to avoid Cesarean section. External cephalic version: The process by which the fetus can be turned from feet- or butt-first in the uterus to head-first can be sometimes made more successful by amnioinfusion by increasing the space the fetus has to move. Preterm premature rupture of membranes: This