Q: A lot of women these days seem to be getting their labor induced because they have oligohydramnios, or too little amniotic fluid. How is this determined? And how accurate is the test that is done to show that this “problem” exists? Is it a real problem? If so, what causes it?
— Anonymous
A: Doctor: “You have too little water. The ultrasound shows oligohydramnios, which means decreased amniotic fluid. Your baby is in trouble! We’ll induce labor and try to avoid a cesarean.”
These are words pregnant women often hear from well-meaning obstetricians. The only problem is that the reason given for interfering with nature has no medical basis. Too little water or too much water are associated with problems in the newborn. That is true. But it is not possible at this time to accurately estimate whether there is too little or too much water until after the baby is born.
This is similar to the problem of estimating the fetus’s weight. The estimated fetal weight is most accurate for average size babies and not as accurate for very small and for very big babies. Those of course, are the babies for which the estimate is needed.
A study in the November 1998 issue of Obstetrics & Gynecology, the journal of the American College of Obstetricians and Gynecologists (Obstet Gynecol 92:5: 823–27) looked at 1038 women who had their amniotic fluid measured by ultrasound near the end of pregnancy. The technician measures, in centimeters, the length of the pockets of amniotic fluid that are seen on the screen and then takes an average of the some of the pockets surrounding the fetus. The pockets surrounding the fetus depend on its position at the time of measurement. The conclusion of this study is that indexing amniotic fluid by measuring the pockets of amniotic fluid—Amniotic Fluid Index (AFI)—is “a poor screening test” to identify infants at risk. AFI is simply not sensitive or accurate enough to be used as a diagnostic tool. This is the only tool that is used to date. The study mentioned that scientists are trying to develop a tool that will be useful for diagnosis of fetuses at risk.
Unfortunately, sometimes women are told that they have too little water or too much water, without any ultrasound measurements, after the doctor palpates the uterus. Clearly, it is impossible to accurately assess that there is too much water or too little water by just feeling the abdomen.
— Judy Slome Cohain, in Midwifery Today eNews
