Effect of high amniotic fluid pressure on fetal circulation

Abstract

The purpose of this study was to investigate the effects of high amniotic fluid pressure (AFP) created by amnioinfusion on fetal circulation. Five pregnant goats whose fetuses had a mean gestational age of 131 +/- 2 days (term 145 days) were used. After a 30 minute control period, 1500 ml of warm saline was infused to the amniotic cavity over a period of 30 minutes. The AFP gradually increased during amnioinfusion and remained 2-3 mmHg above the control level for 3 hours after amnioinfusion. Fetal arterial pH (FpH) tended to decrease, and there was a significant negative correlation between the FpH and AFP (r = -0.723). Fetal arterial pO2 also tended to decrease and negatively correlated to the AFP (r = -0.59). On the other hand, fetal arterial pCO2 tended to increase and positively correlated with the AFP (r = 0.75). Although amnioinfusion is useful for improving the status of a distressed fetus, the fetal condition may be jeopardized at the same time. Therefore, careful monitoring of the AFP and fetal status is recommended during amnioinfusion.

Hypothesis: The Placental ‘Steal’ Phenomenon – A Possible Hazard of Amnioreduction

“…After a large amniodrainage the amniotic pressure falls signifi cantly and rapidly. The effect of the reduced amniotic fl uid pressure has been studied in animal models [26,27] , patients [28] and mathematical models [29] . Amnioreduction decreases the raised amniotic fl uid pressure and uterine size that are associated with polyhydramnios, which result in an increase in placental thickness.…”

Prenatal diagnosis of fetal genital prolapse

“…Postnatal examination confirmed the diagnosis of fetal vaginal vault prolapse and ruled out other fetal congenital anomalies. In addition, polyhydramnios, causing increased intra‐abdominal pressure for the fetus and fetal malpresentation, was evident in our case10, 11.…”

Effects on the Maternofetal Unit of the Rabbit Model after Substitution of the Amniotic Fluid with Perfluorocarbons

“…Increasing the amniotic pressure by infusing amniotic cavity with normal saline in goats has been shown to compromise the fetal condition by lowering fetal pH and increasing fetal pCO 2 [17] . Since fi lling the uterine cavity with PFC, a fl uid of double the weight for volume compared to water, a higher static pressure and pressure gradient along the body axis could have adversely affected the circulation of the fetus.…”