Multiple marker screening (MMS) is a test used to assess the chance for a baby to have one of three specific birth defects: Down syndrome (Trisomy 21), Edward syndrome (Trisomy 18), and Open Neural Tube defects.  This risk assessment is determined based on the levels of up to four proteins present in maternal blood (AFP, hCG, estriol, and possibly DIA) along with demographic variables.  It is important to remember that this is a screening tool, NOT a diagnostic test and therefore it cannot detect or rule out these conditions with certainty.  It only indicates that a patient might be at specific risk for having a baby with one of these conditions.  These women should be offered further counseling and possibly additional testing that may be diagnostic.

 

Note that nuchal translucency is a screening option between 11-14 weeks EGA.  Nuchal translucency screens for Down Syndrome (trisomy 21) and Edward syndrome (trisomy 18), but not open neural tube effects.  Women who have had nuchal translucency screen should be offered the option of MSAFP only  (NOT quad screen or triple screen) to screen for neural tube defects at 15-21 weeks EGA.

 

1.     MMS  testing is performed between 15 and 21 6/7 weeks gestation if screen is sent to Labcorp; it is performed between 15 and 22 6/7 weeks gestation if screen is sent to UNC.  This is an elective, not required test.

2.     Plan to discuss the option of MMS testing and provide the patient with a brochure in advance of the appointment when the blood is to be drawn to allow the patient time to consider this testing option.  MMS information can be obtained in English and Spanish from Lab Corp or the March of Dimes.

3.     MMS is not a diagnostic test.  Rather, it is a screening tool to allow for patient specific risk assessment.

4.     A positive result does not mean that the baby has one of these conditions, but that there is an increased concern, warranting a “closer look.”

5.     All positive results should be referred for genetic counseling, ultrasound and amniocentesis within one week of receiving verbal result.

6.     A negative result cannot rule out these conditions, but means that the chance for these birth defects is less than the established cutoff of the lab.

7.     Make sure that the variables are correctly entered onto the requisition.  This will ensure that the results are interpreted properly.  The variables are gestational age, maternal age, maternal weight, if the mother is an insulin dependent diabetic, multiple gestation (twins, triplets, etc.), and ethnic background.

8.     If the MMS results are “negative,” and variables are correct, no additional diagnostic testing should be offered in the absence of advanced maternal age, ultrasound abnormalities or ultrasound markers of unclear significance (choroid plexus cyst, echogenic focus),  or a positive family history. 

 

 

 

1.     Confirm variables used to calculate MMS, particularly gestational age. * (Note:  MMS should not be ordered on a patient without a known LMP or a documented gestational age by ultrasound.  Approximately 40% of positive MMS results can be explained by inaccurate gestational dates.  This can create unnecessary anxiety for the patient and staff).  The patient’s known LMP and/or ultrasound are the best resources. 

2.     If the Bipareital diameter (BPD) from ultrasound dating shows the gestational age used to calculate MsAFP was different by greater than 10-14 days, the specimen needs to be recalculated.  Composite gestational age should not be used to estimate gestational age.  Results should not be recalculated for patients who are at an increased risk for Edward Syndrome (due to the association with intrauterine growth restriction).

3.     If the patient is at risk for Down syndrome or Edward syndrome, she should be referred to the Fetal Diagnostic Center for genetic counseling, ultrasound and amniocentesis. A repeat MMS is not indicated for these types of results.

4.     If the patient is at risk for neural tube defects:

 

a.     Patients with an elevated AFP MoM value that is less than 2.5 MoM, should be offered  redraw of an AFP-only at the clinic. If repeat  AFP is negative, no referral is needed.

b.     Patients with elevated AFP MoM values or that remain increased             above a normal range on repeat assessment should be scheduled for level II ultrasound, genetic counseling, and possible amniocentesis.

c.     Many patients will wish an immediate referral after a single elevated AFP value.  This request should be honored.

The patients should be made aware that a “positive” result does not imply that the baby has the diagnosed condition.  It is often helpful to refer to a positive result as an “unusual result” that needs “a closer look”.  Most patients with a usual result will continue to deliver babies who are healthy.

 

 

 

If you have any questions about MMS screening, call the laboratory that performed the screen or the genetic counselors at (919) 684-3604.

 

* NOTE:   MMS should not be ordered on a patient without a known LMP or a documented gestational age by ultrasound.  Approximately 40% of positive MMS results can be explained by inaccurate gestational dates.  This can create unnecessary anxiety for the patient and staff.

 

 

 

 

 

 

 

 

 

Prepared in conjunction with the

Division of Maternal-Fetal Medicine

Duke University Medical Center

 

 

 

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The Clinical Care Guidelines Development Committee of the Perinatal Improvement Board of Duke University Health System has developed a series of multi-disciplinary protocols to offer guidance to health care providers who are caring for pregnant women with high risk conditions.

 

These protocols are designed to assist health care providers in the management of a variety of problems that occur in pregnancy and the time of delivery. They should not be interpreted as standard of care, but instead represent only general guidelines for the care of pregnant women with high risk conditions.  We recognize that services offered by individual providers depend not only on their training, experience and institutional resources, but on the medical facts and circumstances of the specific care situation.

The protocols remain the intellectual property of the Duke University Health System.  They cannot be reproduced in whole or part without the expressed permission of the Health System.

 

These protocols are reviewed by the Department of Obstetrics and Gynecology Division of Maternal-Fetal Medicine, the Department of Pediatrics Division of Neonatology and the Department of Anesthesiology Division of Women’s Anesthesia.  Please contact Andra H. James (andra.james@duke.edu), Chair, Clinical Care Guidelines Development Committee of the Perinatal Improvement Board with ideas for additional protocols.