OB-GYN-L Messages for June, 2005: Re: Oligohydramnios, dolicocephaly and elevated AFP

Re: Oligohydramnios, dolicocephaly and elevated AFP

From: Henry Gregor

henrygregor@yahoo.com

Tue Jun 28 14:03:29 2005

Jim Wang <jimwangmd@yahoo.com> wrote: Thank you so much for the responses from Lynn and Dan.

Oligo on 18-week US is indeed quite subjective. Three USs performed by radiology dept in the past 7 days resulted in diagnoses of "mild-to-moderate" oligo on first scan; "severe" oligo on the second; and "moderate" oligo on the last (AFI measured only on the third US to be 5.6) The head, brain, spine, stomach, heart, kidneys and bladder appear normal on US. Placenta is low-lying, but not abnormal.

The patient is actually my wife. Our desires, like most first-time expectant parents, are to be conservative and safety of the baby and mother first. In light of the numerous signs (slowly rising BHCG, oligohydramnios, dolicocephaly, elevated AFP) of a possibly abnormal pregnancy, amniocentesis would be very helpful. We have been told that the risk of amniocentesis in the setting of oligo would be "higher" than usual; and the chance of finding spinal bifida or chromosomal abnormality is relatively "low". However, we find it difficult to make a decision when the risk of the procedure and the probability of finding abnormality are not quantified (i.e. in numeric percentage). If the risk % clearly exceeds the test positive rate, we would not wish to take such unfavorable gamble.

I can understand that the risk is relative and that a numerical risk estimate may not be exact. Yet, without a quantifiable risk/benefit analysis, we would not be able to make an informed decision. Greatly appreciate any input to help us decide whether or not to proceed with amnio-infusion/centesis:

1. Estimated risk of amnio-infusion/centesis in the setting of oligo (AFI 5.6)? 2. Probability of finding spinal bifida or chromosomal abnormality in light of anatomically normal US? 3. Utility of delaying any procedure at this time and repeating US in 2 and/or 4 weeks to see if more detailed anatomy can be visualized? 4. Optimal timing for amnio-infusion/centesis?

Thank you, Jim Wang, MD

At Wed, 22 Jun 2005, Lynn D. Montgomery, M.D. wrote: >
>1. Any association between oligohydramnios, dolicocephaly and elevated AFP?
>Can oligohydramnios alone cause dolicocephaly and elevated AFP? Or are these
>separate problems?
>
>**First, oligohydramnios at 18 weeks is a relative finding and I find
>overcalled by many. Aside from this, dolicocephaly is a common finding at
>18 weeks gestation, oligo or not. As for a relationship between all three
>findings, there can certainly be an association in the picture of
>aneuploidy.
>
>2. What is the added risk of amniocentesis in the setting of
>oligohydramnios? Does the cumulative risk of the procedure exceeds the
>probability of finding spina bifida or chromosomal abnormality by
>amniocentesis?
>
>**Again, the risk is relative, but the need for diagnosis must be added to
>the equation. If oligohydramnios is significant enough to preclude adequate
>visualization, amnioinfusion can be accomplished. This typically allows
>better visualization and may allow for a cell sampling
>
>3. Elevated AFP- is there any added utility of doing amniocentesis if the
>head, spine and stomach appear normal on US? Yes, there may be a small spina
>bifida that is not apparent on US. But if we can see leg movements on US
>and all other findings are normal, I am not sure any results from
>amniocentesis will sway us to intervene.
>
>**First, approximately 90-95% of spinal defects should be visible via
>ultrasound in normal conditions. Depending upon the degree of oligo, the
>detection rate may be compromised. Now, approximately 85% of neural tube
>defects will have an associated hydrocephalus so if you are comfortable with
>your neuroimaging, this can help. Keep in mind that fetuses with aneuploidy
>can have a normal anatomic survey. Additionally, it has been show that
>ultrasound visualization of fetal lower extremity movement is not a reliable
>predictor of a neural tube defect or for potential lower extremity function
>following birth in a fetus with a neural tube defect. Finally, with regard
>to intervention for amnio or anything else, the patients desires, following
>a detailed discussion, are paramount in how to proceed.
>
>4. Dolicocephaly at 18-weeks gestation- sign of chromosomal abnormality? US
>at 13-weeks gestation did not show dolicocephaly. Could oligohydramnios be
>the cause?
>
>**Asked and answered.
>
>Thank you.
>
>**Please sign your posts in the future...
>Lynn

-- Jim Wang, MD

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