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    MFM Consult: The twin with IUGR

    Your patient has a twin gestation at almost 29 weeks and one of the fetuses has IUGR. How should you proceed?


    A 26-year-old G2, P1 is in your office for her routine prenatal visit. You know she's carrying twins and today she is 28 6/7 weeks by good dates. Her prenatal labs have all been normal and she has shown up for all her visits. Her prior delivery was a singleton infant who delivered vaginally at term without complications.

    The patient has just come from your ultrasound unit with the following report:

    A: vertex, biometry consistent with 26 wks, estimated fetal weight (EFW) 715 g, <10%; amniotic fluid adequate

    B: vertex, biometry consistent with 28 4/7 wks, EFW 1059 g, 40%; amniotic fluid adequate;

    Anterior placenta; umbilical artery Doppler S/D ratio is normal on twin A.

    You tell the patient that one of the babies is small and not growing as well as it should, and that you need to gather some more information before you can give her a plan.

    A step-by-step management approach The approach to intrauterine growth restriction (IUGR) in a twin is similar to that for IUGR in a singleton, but of course, the management is more complex. As most clinicians know, IUGR increases the risk of fetal demise. Therefore, when it is diagnosed in discordant twins, the goal is to balance the risks of prematurity in the unaffected twin with the risks of fetal demise in the growth-restricted fetus when deciding on the timing of delivery.1

    Respond to NST results. The first step is to make sure the latest fetal assessments are reassuring. If one fetus has nonreassuring testing, you would either deliver or admit the mother for continuous monitoring, depending on how non-reassuring the reading was. In addition, you should also look for the cause of the nonreassuring reading and determine placentation before devising a definitive treatment plan. Send the patient for a non-stress test (NST) or biophysical profile (BPP) on both fetuses, if you have not already performed those tests that day. This allows you to reassure the patient and buy some time while you are figuring out the rest of the plan.

    Look for the etiology of the IUGR. Try to determine if the IUGR is being cause by placental, fetal, or maternal factors.

    First, review the patient's early ultrasounds to see if placentation was ever documented. If the gestation is monochorionic, then you should be more concerned about potential twin-twin transfusion syndrome (TTTS). A dichorionic gestation rules out TTTS. (In this case we'll assume the placentation is dichorionic.) Abnormal placentation, such as previa or a velamentous cord insertion, also can cause IUGR.

    Next, review the current ultrasound and any previous ones to determine if any anomalies were noted and what the pattern of growth has been. If anomalies are present, strongly consider amniocenteses (both fetuses) for chromosomes.

    Also check the U/Ss for any viral markers in the IUGR fetus (intracranial or intrahepatic calcifications, ventriculomegaly, hydrops). If viral markers are present, consider amniocenteses (both fetuses) for viral cultures.

    Then review the patient's blood pressure to look for current signsof preeclampsia or a history of chronic hypertension. Given that she has twins and thus is at increased risk for preeclampsia, you may decide to send for routine preeclampsia labs as part of your workup.

    Review the patient's history for risk factors for IUGR, such as smoking, other drug use, underlying medical problems (hypertension, diabetes, renal disease, other autoimmune disease, prior baby with IUGR), a nutritional disorder, and anemia. A review of maternal weight gain may also uncover a risk factor. As with singletons, poor maternal weight gain in a twin pregnancy can be associated with poor fetal growth. However, these maternal-specific factors, in general, are more likely to be associated with IUGR in both fetuses rather than only one.

    Consider steroids. Consider giving the patient antepartum steroids, because her likelihood of delivering before 34 weeks is higher now that one twin has IUGR at 28 weeks.


    Sarah J. Kilpatrick, MD, PhD
    Dr. Kilpatrick is the Helping Hand Endowed Chair in the Department of Obstetrics and Gynecology, Cedars-Sinai Medical Center, Los ...


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