Multifetal gestation: Clinical sciences

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Introduction0:00–0:45

Multifetal gestation is any pregnancy in which more than one fetus is present. This includes twin triplet and other higher order pregnancies.
Multifetal gestations carry increased maternal risks including diabetes and preeclampsia, as well as increased fetal risks such as preterm birth and intrauterine fetal demise.
Also known as IU FD. The amnionicity, meaning the number of amniotic sacs and the chorionicity, meaning the number of placentas influenced the degree of risk for the pregnancy.
When a patient presents with a suspected multifetal gestation, your first step is to obtain a focused history and physical examination.

History and Physical0:45–2:04

Patients may report significant nausea and vomiting or hyperemesis which is due to the increased beta human chorionic gonadotropin levels that occur with multifetal gestations.
They may also have certain risk factors for a multifetal gestation such as assisted reproductive technology, like in vitro fertilization or ovulation induction or increased maternal age or parity on a physical exam.
You may notice the uterine size is greater than expected based on your patient's last menstrual period. Next order an obstetric ultrasound which will be most accurate when performed at the end of the first trimester or early second trimester.
The ultrasound allows you to assess the number of fetuses, the chorionicity and the amnionicity, which will guide the management of the pregnancy.
This is also a good time to consult the maternal fetal medicine team for their involvement in your patient's care. If the obstetric ultrasound demonstrates two fetuses, then you know this is a twin pregnancy.

Dichorionic diamniotic twins2:04–5:46

Next. Look for the twin peak sign, also known as the lambda sign, which looks like a triangular wedge of placental tissue extending at the base of the inter twin membrane.
If this is present, then you know there are two placentas and each fetus is separated by a thick membrane. So your diagnosis is a dichorionic diamniotic twin pregnancy.
Now, standard care for all patients with a multifetal gestation include counseling on appropriate weight gain and nutritional needs.
This includes increased amounts of folic acid and other micronutrients to ensure there's enough available for multiple fetuses to develop because of the increased risk of preeclampsia.
Order a low dose aspirin to start between 12 and 28 weeks of gestation. Next offer fetal aup bloody screening and be sure to cover some specific points with your patient.
For example, explain that while euploidy screenings like cell free DNA testing or the quad screen can be used for multiples, caution your patient that this testing can be less accurate with a multiple gestation and it cannot determine which fetus might be affected.
Also let them know that nuchal translucency, which is an ultrasound that looks at the thickness of the back of the fetal neck is the only non invasive option that separately evaluates each fetus.
Additionally explain that diagnostic testing such as chorionic villus sampling or amniocentesis usually provide information on each fetus.
But keep in mind that these are invasive tests and counsel your patient on risks and benefits. Next.
Since multifetal gestations are at increased risk of developing structural anomalies, perform an extended fetal anatomic survey and finally start antenatal fetal surveillance at 36 weeks of gestation because of an increased risk of IU FD.
Ok. Let's go over some specific care needed for dichorionic dye amniotic twin pregnancies starting at 20 weeks.
Complete serial ultrasounds every 3 to 4 weeks to evaluate for fetal growth restriction, which will provide information for counseling on the mode of delivery.
A trial of labor is often possible if certain criteria are met, such as when both twins have a cephalic presentation, you could also attempt a trial of labor if the presenting twin has a cephalic presentation and the second twin is not cephalic.
In this case, you can consider attempting a breech extraction. As long as the second twin isn't estimated to be more than 20% larger than the first.
It's also reasonable to perform ac section for a twin gestation. If you're not experienced with breech extractions or for patient preference with uncomplicated dichorionic diamniotic twin pregnancies delivery should occur between 38 weeks, zero days of gestation and 38 weeks.
Six days of gestation though it's common to deliver earlier if medically indicated. Let's now look at another scenario where the ultrasound shows two fetuses with a thin intertwin membrane that's inserted at a 90 degree angle into one shared placenta referred to as the T sign.

Monochorionic diamniotic twins5:46–8:35

This makes the diagnosis, monochorionic diamniotic twins. As with care for all multifetal gestations, counseling includes appropriate weight gain and ensuring adequate nutritional needs are met.
Prescribe low dose aspirin offer an ploidy screening and perform an extended fetal anatomic survey. Also perform antenatal fetal surveillance.
But this time start at 32 weeks of gestation due to the higher risk from a shared placenta. There are some additional aspects of care for this type of multifetal gestation that are slightly different from other multifetal gestations starting at 16 weeks.
Complete serial ultrasounds every two weeks to assess for twin to twin transfusion syndrome or T TT S T TT S occurs when there's an uneven distribution of placental blood flow where one twin doesn't have enough blood flow and the other twin has too much.
This can lead to severe complications. And even IU FD, if T TT S is detected, it might be necessary to use laser therapy to ablate specific placental vessels to redistribute placental flow evenly.
Now, due to the increased risk of cardiac defects in monochorionic dye amniotic twins, fetal echocardiograms are needed in the second trimester.
Moreover, these twins are at a very high risk for preterm birth So consider inpatient hospitalization in the third trimester when it appears delivery will be within the next seven days, administer steroids for neonatal benefits.
As far as the mode of delivery goes, this type of twin pregnancy might be appropriate for a trial of labor depending on the same factors as dichorionic diamniotic twins.
So be sure to counsel your patient on options for delivery by C section or by trial of labor. Lastly, because of the higher risk of adverse outcomes with a shared placenta.
Delivery is recommended between 34 weeks and zero days and 37 weeks and six days of gestation though it might be earlier if medically indicated.

Monochorionic monoamniotic twins8:35–10:47

Now, the idea of a placenta shared by two fetuses might seem risky but it can get even riskier. Let's go back to our ultrasound and talk about what else you might see.
It's possible to see two fetuses and one placenta but no intertwin membrane making your diagnosis. Monochorionic monoamniotic twins.
This is the rarest type of twinning and also presents the highest risk. Your standard multifetal gestation care is the same.
Meaning counseling on weight gain and nutrition, low dose aspirin, fetal Aidy screening and extended fetal anatomic survey.
However, with one placenta and one amniotic sac, there's a higher risk of IU FD. So your timing to start antenatal fetal surveillance needs to be individualized after a discussion with the patient about the potential for early gestational age at delivery.
Special care for monochorionic monoamniotic twin pregnancies includes serial ultrasounds every two weeks, starting at 16 weeks to look for signs of T TT S and to monitor growth.
Once again, complete a fetal echocardiogram in the second trimester, there's also a risk of sudden unpredictable fetal demise from cord entanglement because of this risk offer inpatient hospitalization in the third trimester to allow for antepartum testing at least once daily, monochorionic monoamniotic twins will be delivered preterm.
So, steroids should be given within seven days of anticipated delivery because of the twins share an amniotic sac vaginal delivery is not recommended due to the risk of cord entanglement.
So, plan for delivery by C section between 32 and 34 weeks of gestation unless an alternate indication arises all right time to go over the final ultrasound findings.

Higher order multiples10:47–12:17

If you see more than two fetuses on ultrasound, diagnose higher order multiples such as triplets, quadruplets or quintuplets.
These pregnancies are rare but management is similar to twin pregnancies. This means counseling on weight gain and nutrition, low dose aspirin, fetal aneuploidy screening, extended fetal anatomic surveys and antenatal fetal surveillance starting at an individualized gestational age.
These pregnancies will also need serial ultrasounds every two weeks, starting at 16 weeks and fetal echocardiograms if any of the fetuses share placentas again.
Hospitalization in the late second or early third trimester may be considered if any of the fetuses share amniotic sacs but may also be medically indicated for factors like preterm, prelabor rupture of membranes or threatened preterm, labor delivery will be preterm.
So, administer steroids within seven days of anticipated delivery. The exact timing of delivery needs to be individualized but should occur by C section usually in the moderate or late preterm period which is around 32 to 37 weeks of gestation.
All right. As a quick recap, multifetal gestation refers to any pregnancy in which there is more than one fetus.

Review12:17–13:09

The diagnosis is made by ultrasound, looking at the number of fetuses present as well as the number of placentas and amniotic sacs.
These pregnancies are high risk. So, extra counseling and surveillance is needed including antenatal fetal surveillance, serial ultrasounds and screening for twin to twin transfusion syndrome or T TT S.
When fetuses share a placenta delivery should occur at 38 weeks and zero days to 38 weeks and six days for dichorionic dye amniotic pregnancies and even earlier for other types of twins and higher order