Below is the content from a letter that was recently mailed out to the majority of our referring physicians regarding recent updates implemented in our practice.
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To Whom It May Concern:
We appreciate the opportunity to be involved in your patients’ care. In order to stay in line with recent advances in prenatal technology, we have implemented some changes. As you may recall, according to the latest recommendations from the American College of Obstetricians and Gynecologists (ACOG,) screening and diagnostic options for chromosomal abnormalities should be offered to all pregnant women regardless of maternal age or other risk factors.
To continue offering excellent quality of care, data for our second trimester ultrasound screening for Down syndrome, trisomy 13, trisomy 18, and structural abnormalities has been reassessed and updated based on more recent literature. In the past a second trimester ultrasound risk assessment for Down syndrome was able to be performed between 17 and 23 weeks gestation. The timing of this screening has changed and will no longer be available from 21-23 weeks gestation. Instead it may now be performed from 14-20 weeks gestation. Even though an assessment for Down syndrome can be provided earlier in pregnancy than before, evaluations prior to 18 weeks gestation may provide suboptimal images of the fetal anatomy such as heart and spine. Therefore we highly recommend and prefer patients be referred between the range of 18-20 weeks gestation for optimal views providing a risk assessment for Down syndrome, trisomy 13, trisomy 18, open neural tube defects, and other structural abnormalities. An extensive anatomical survey for structural abnormalities is still available until 28 weeks gestation. As always, it is important for patients to realize that prenatal ultrasound is not able to identify all fetal structural abnormalities.
The recent ACOG Practice Bulletin states, “A strategy that incorporates both first- and second-trimester screening should be offered to women who seek prenatal care in the first trimester.” This is not meant to suggest screening women twice and in fact the same bulletin recommends avoiding screening a pregnancy more than once for chromosome abnormalities as this can often cause confusion and anxiety for patients. It is intended to offer patients seeking early pregnancy care a choice as to whether they would prefer a screening options in the first trimester (first trimester screening), screening options in the second trimester (maternal serum screening or the targeted ultrasound screening for Down syndrome), or integrated/sequential screening.
For the most accurate risk assessment for Down syndrome and trisomies 13 and 18, we continue to recommend first trimester screening between 11.4 and 13.9 weeks gestation utilizing GeneCare Laboratories for serum analysis. The ultrasound portion of first trimester screening consists of a measurement of the thickness at the back of the fetal neck (NTT) which is able to detect approximately 80% of fetuses with Down syndrome, trisomy 13 and trisomy 18 and 40% of congenital heart defects. The presence or absence of a nasal bone may further alter these risks. This is a valuable tool especially for multiple gestation pregnancies in which the second trimester serum screening has significantly decreased detection rates. When this ultrasound is combined with the recommended but optional serum fingerstick the detection rate is increased to 91-95% for Down syndrome and 97% for trisomies 13 and 18. These detection rates are based on the following publication Nicolaides, HK. Seminars in Perinatology, Vol 29, Issue 4, 2005, 190-194 which includes prospective FMF studies of more than 225,000 patients. This screening test does not evaluate for most open spine defects or structural abnormalities. Therefore we recommend a second trimester extensive ultrasound for fetal anatomic defects as follow-up to first trimester screening.
Though integrated and sequential screening is available, it is not standardly performed in our clinic due to a combination of factors including their lower detection rates (compared to first trimester screening utilizing GeneCare Laboratories for the serum analysis), increased patient anxiety during the wait time, failure of patients to return for a second blood draw resulting in no results, and the loss of chorionic villus sampling as a diagnostic testing option.
If a patient chooses first trimester screening, they should not undergo a second screening technique such as the maternal serum triple or quad screen. This is especially true for patients that are advanced maternal age as this second trimester serum screen is frequently abnormal for Down syndrome, even following a normal first trimester screen.
We continue to be available to you to discuss questions or concerns regarding the changes outlined above and have included two updated tables, one with screening options and the other with diagnostic testing information, which may be beneficial for you and your staff, but are not necessarily patient appropriate. We have also included a new prenatal screening options sheet which may be a valuable tool to help patients decide which screening option is best for them. The lower portion of this sheet has our information which can be easily removed to add your own practice information and an electronic version is available on our website for your convenience. Finally, a copy of our map and an updated physician order form, and patient literature are included to assist you.
We hope this information will be beneficial for your patients’ care. If you would like any additional copies of these documents please complete the attached form and fax it back to us at (317) 415-8071. It is also possible to download the majority of our forms (including those that are typically mailed to patients at the time an appointment is scheduled) from our website at http://www.cpdx.com/forms. As always, when referring a patient to our office, please remember to fax a copy of all applicable medical records including the earliest ultrasound after seven weeks gestation and the actual lab sheet indicating the patient’s blood type.
We are always happy to answer questions regarding the application of newer carrier screening for single gene disorders including fragile X and spinal muscular atrophy in addition to ethnicity based screens including cystic fibrosis, hemoglobinopathies and panels for individuals of Jewish descent. We appreciate your continued confidence in our practice and thank you for allowing us to participate in your patients’ care.
Please do not hesitate to contact us for additional information.
Sincerely,
James Sumners, MD
Maurice Eggleston, MD
