Understanding Hydramnios: Causes, Risks, and What to Expect

Question
Hi,
At week 28, an ultrasound showed an excess of amniotic fluid.  According to this test, my AFI ( amniotic fluid index) is 26.4 cm.

We ruled out the following:
- I don't suffer from gestational diabetes
- I don't have RH blood incompatibility
- I am not carrying twins
- The fetal neural tube is okay; no abnormality.

My questions are the following:
1) Is an AFI of 26.4 is considered a severe or mild hydramnios?  An AFI greater than 25 is considered hydramnios, while the average AFI is 15.

2) What is the danger for the fetus?  

3) Should I be worry (well, I am worry, but I not sure to understand the level of risk).

Thank you,

Gen.

Answer
Dear Gen,

Typically, there is a reason for an AFI over 25 at 28 weeks but in up to 50% of cases, there are simply no risk factors for polyhydramnios ever found. It may be that there is an issue with the baby's gastrointestinal tract or swallowing mechanism. At this point, there just may not be any way to know for sure.

In a 1990 study, 20% of cases of polyhydramnios involved associated fetal anomalies, including problems of the gastrointestinal system (40%), central nervous system (26%), cardiovascular system (22%), or genitourinary system (13%).

As far as the "severity" of your AFI, I can put it this way - in a pool of 100 pregnant women at 28 weeks, your AFI result would be higher than at least 99 of them, if not all 100 (97% are at or below 24.9 at 28 weeks). The 26.4 AFI would be considered high enough for your doctor to want to attempt to determine whether there is an underlying cause which needs to be prepared for at delivery time. I'm sure they will continue testing and keep a close eye on you for the remainder of your pregnancy. Preterm labor and delivery occurs in approximately 26% of mothers with polyhydramnios. Other complications are premature rupture of the membranes (PROM), abruptio placenta, malpresentation, C-section delivery, and postpartum hemorrhage. I'm quite sure your doctor/medical team will keep the health and welfare of you and your baby their top priority in determining your plan of care.

I hope this has helped you and answered your question. I wish you well and a Merry Christmas.

Brenda