LE5 OB Flashcards
A 26-year-old woman with a monochorionic diamniotic (MCDA) twin pregnancy undergoes an ultrasound at 22 weeks. The scan reveals the following:
Twin A: Polyhydramnios, large for gestational age
Twin B: Oligohydramnios, significantly smaller
What is the most likely diagnosis?
A. Selective Intrauterine Growth Restriction (sIUGR)
B. Twin Reversed Arterial Perfusion (TRAP) Syndrome
C. Twin-Twin Transfusion Syndrome (TTTS)
D. Twin Anemia-Polycythemia Sequence (TAPS)
C. Twin-Twin Transfusion Syndrome (TTTS)
Rationale:
TTTS is a complication specific to MCDA twins due to vascular anastomoses in a shared placenta.
Donor Twin (B) → Oligohydramnios, growth restriction, anemia.
Recipient Twin (A) → Polyhydramnios, macrosomia, heart failure risk.
sIUGR does not cause amniotic fluid discordance.
A 28-year-old woman with an MCDA twin pregnancy is diagnosed with Stage III TTTS at 24 weeks. Doppler studies reveal absent or reversed end-diastolic flow in the donor twin. What is the best treatment?
A. Amnioreduction of the recipient twin’s sac
B. Selective fetoscopic laser ablation of placental anastomoses
C. Immediate delivery via C-section
D. Cord ligation of the donor twin
B. Selective fetoscopic laser ablation of placental anastomoses
Rationale:
Laser ablation is the definitive treatment for severe TTTS (Stage II or higher).
Amnioreduction only provides temporary relief but does not correct the underlying issue.
Preterm delivery before viability (<25 weeks) is not ideal unless fetal distress occurs.
A 32-year-old woman with an MCDA twin pregnancy at 30 weeks presents for a routine ultrasound. Doppler studies show the following:
Twin A: Middle cerebral artery (MCA) peak systolic velocity (PSV) is increased
Twin B: MCA PSV is decreased, with signs of polycythemia
Which fetal complication is most likely?
A. Twin-Twin Transfusion Syndrome (TTTS)
B. Selective Intrauterine Growth Restriction (sIUGR)
C. Twin Anemia-Polycythemia Sequence (TAPS)
D. Twin Reversed Arterial Perfusion (TRAP) Syndrome
C. Twin Anemia-Polycythemia Sequence (TAPS)
Rationale:
TAPS is a chronic, slow transfusion imbalance in MCDA twins due to small arterio-venous shunts.
MCA Doppler is key: High PSV (anemia) in one twin, low PSV (polycythemia) in the other.
Unlike TTTS, there is no major amniotic fluid imbalance.
A 29-year-old woman with an MCDA twin pregnancy undergoes an anatomy scan at 22 weeks. Ultrasound reveals:
Twin A: Normal heart function
Twin B: Acardiac, absent cardiac activity, abnormal body development
What is the best next step?
A. Expectant management with serial ultrasound monitoring
B. Fetal echocardiography to assess Twin B’s heart function
C. Fetoscopic laser ablation or radiofrequency ablation (RFA) of Twin B’s cord
D. Immediate delivery regardless of gestational age
C. Fetoscopic laser ablation or radiofrequency ablation (RFA) of Twin B’s cord
Rationale:
TRAP sequence occurs in MCDA twins when one twin (acardiac) receives reversed arterial flow.
Pump twin is at risk of high-output cardiac failure.
Cord occlusion via laser or RFA is required to prevent heart failure in Twin A.
A 30-year-old woman with an MCDA twin pregnancy undergoes ultrasound at 28 weeks. Twin A is growing appropriately, but Twin B is measuring >25% smaller with absent end-diastolic flow in the umbilical artery. What is the best course of action?
A. Expectant management with weekly ultrasound monitoring
B. Immediate delivery via C-section
C. Selective fetoscopic laser ablation
D. Close Doppler monitoring with consideration for early delivery
D. Close Doppler monitoring with consideration for early delivery
Rationale:
sIUGR is diagnosed when one twin is ≥25% smaller.
Absent or reversed umbilical artery end-diastolic flow = High risk of fetal demise.
Management depends on Doppler trends; delivery may be needed if worsening occurs.
A 34-year-old woman with an MCDA twin pregnancy presents for routine ultrasound at 30 weeks. One twin has no cardiac activity, while the other appears viable. What is the next best step?
A. Immediate C-section to prevent complications in the surviving twin
B. MRI to assess for brain injury in the surviving twin
C. Expectant management without further intervention
D. Umbilical cord coagulation of the deceased twin
B. MRI to assess for brain injury in the surviving twin
Rationale:
In MCDA twins, single intrauterine fetal demise (IUFD) increases the risk of ischemic brain injury in the surviving twin.
MRI is used to detect hypoxic-ischemic injury.
Immediate delivery is not required unless there is fetal distress.
A 30-year-old woman with an MCMA twin pregnancy at 30 weeks is undergoing biweekly ultrasound surveillance. The scan shows intertwined umbilical cords but normal fetal heart rates. What is the best management plan?
A. Continue biweekly monitoring until spontaneous labor occurs
B. Hospital admission for continuous fetal monitoring at 32 weeks
C. Immediate C-section at 30 weeks
D. Induction of labor at 37 weeks if no distress
B. Hospital admission for continuous fetal monitoring at 32 weeks
Rationale:
MCMA twins are at high risk for sudden fetal death due to cord entanglement.
Recommended management = Hospitalization at 32 weeks with continuous monitoring.
Elective delivery at 32-34 weeks via C-section to reduce risk of cord accidents.
A 28-year-old woman with a dichorionic diamniotic (DCDA) twin pregnancy presents for her first prenatal visit at 10 weeks gestation. She asks how often she should have prenatal check-ups compared to a singleton pregnancy. What is the most appropriate response?
A. The same as a singleton pregnancy (every 4 weeks until 28 weeks, then every 2 weeks)
B. More frequent visits (every 2 weeks starting at 16-18 weeks, then weekly after 28 weeks)
C. Monthly visits until 36 weeks, then weekly
D. Weekly visits starting in the second trimester
B. More frequent visits (every 2 weeks starting at 16-18 weeks, then weekly after 28 weeks)
Rationale:
Multifetal pregnancies require more frequent monitoring due to increased risks (e.g., preterm labor, growth restriction).
In twins: Visits should be every 2 weeks starting at 16-18 weeks, then weekly after 28 weeks.
More frequent ultrasounds are needed to monitor fetal growth and complications.
A 27-year-old woman with a dichorionic twin pregnancy at 16 weeks asks about her nutritional needs. How much total weight gain is recommended for a woman with a normal BMI?
A. 11-15 kg (24-32 lbs)
B. 16-24 kg (35-50 lbs)
C. 6-10 kg (13-22 lbs)
D. 25-30 kg (55-66 lbs)
B. 16-24 kg (35-50 lbs)
Rationale:
Weight gain in twins should be higher than in singleton pregnancies (~25-35 lbs).
Higher caloric and protein intake is required to support fetal growth.
A 32-year-old woman with an MCDA twin pregnancy at 20 weeks is found to have a hemoglobin level of 10.5 g/dL. What additional supplementation should she receive?
A. Folic acid only
B. Increased iron and folic acid supplementation
C. Calcium and vitamin D only
D. No additional supplementation is needed
B. Increased iron and folic acid supplementation
Rationale:
Iron-deficiency anemia is more common in multifetal pregnancies due to increased blood volume.
Folic acid helps prevent neural tube defects and supports red blood cell formation.
A 29-year-old woman with a monochorionic twin pregnancy at 30 weeks presents with contractions every 5 minutes and a cervical dilation of 3 cm. What is the most appropriate next step?
A. Administer antenatal corticosteroids and magnesium sulfate
B. Immediate cesarean delivery
C. Bed rest and hydration only
D. Perform emergency cerclage
A. Administer antenatal corticosteroids and magnesium sulfate
Rationale:
Antenatal corticosteroids (betamethasone) reduce neonatal respiratory distress syndrome.
Magnesium sulfate provides neuroprotection if <32 weeks.
Cerclage is contraindicated in active preterm labor.
A 30-year-old woman at 37 weeks with a dichorionic diamniotic (DCDA) twin pregnancy presents in labor. Twin A is cephalic, and Twin B is breech. There are no maternal or fetal complications. What is the best mode of delivery?
A. Elective cesarean section for both twins
B. Attempt vaginal delivery
C. Vaginal delivery for Twin A, followed by external cephalic version (ECV) for Twin B
D. Immediate cesarean section for Twin B only
B. Attempt vaginal delivery
Rationale:
Twin A (first twin) is cephalic, making vaginal delivery possible.
If Twin B is breech, vaginal breech delivery can be attempted in an experienced setting.
External cephalic version (ECV) is not always necessary unless there are delivery difficulties.
Cesarean is only required if there are fetal distress or delivery complications.
Indications for Cesarean in Twin Pregnancies
A 35-year-old woman at 36 weeks with an MCDA twin pregnancy is admitted for delivery planning. Twin A is breech, and Twin B is transverse. What is the best mode of delivery?
A. Vaginal delivery
B. External cephalic version (ECV) of Twin A followed by vaginal delivery
C. Cesarean section
D. Induction of labor with oxytocin
C. Cesarean section
Rationale:
Non-cephalic presentation of Twin A is an indication for cesarean delivery.
Twin B in transverse lie further supports the need for C-section.
ECV is not performed on Twin A before delivery.
A 28-year-old woman at 37 weeks with a DCDA twin pregnancy presents in active labor. Twin A delivers vaginally, but Twin B remains in transverse lie. What is the best immediate management?
A. Wait for spontaneous repositioning of Twin B
B. Perform external cephalic version (ECV) for Twin B
C. Perform internal podalic version for breech extraction of Twin B
D. Perform emergency cesarean section for Twin B
C. Perform internal podalic version for breech extraction of Twin B
Rationale:
If Twin B is in transverse lie after Twin A is delivered, repositioning is needed.
Internal podalic version allows for controlled breech extraction of Twin B.
Emergency C-section is not necessary unless there is fetal distress.
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A 30-year-old woman delivers twins vaginally at 37 weeks. After placental delivery, she develops heavy vaginal bleeding and a boggy uterus. What is the most likely cause?
A. Uterine rupture
B. Retained placenta
C. Uterine atony due to overdistension
D. Vaginal laceration
C. Uterine atony due to overdistension
Rationale:
Multifetal pregnancy increases the risk of PPH due to an overdistended uterus.
Uterotonics (oxytocin), uterine massage, and fluid resuscitation are first-line treatments.
A 33-year-old woman is in labor with a DCDA twin pregnancy. Twin A delivers vaginally at 10:15 AM, but Twin B remains intrauterine with normal heart tones. What is the recommended management?
A. Perform immediate cesarean section
B. Allow up to 30 minutes for spontaneous delivery of Twin B
C. Induce contractions with oxytocin if labor stalls
D. Perform external cephalic version (ECV) for Twin B
B. Allow up to 30 minutes for spontaneous delivery of Twin B
Rationale:
Twin B usually delivers within 30 minutes of Twin A.
If labor stalls or there is fetal distress, oxytocin can be used.
C-section is only necessary for complications.
A 30-year-old woman with a trichorionic triamniotic (TCTA) triplet pregnancy at 9 weeks is considering selective reduction. What is the best gestational age for this procedure?
A. Before 8 weeks
B. Between 10-14 weeks
C. At 16-20 weeks
D. After 24 weeks
B. Between 10-14 weeks
Rationale:
Selective reduction is ideally performed in the late first trimester (10-14 weeks).
Early reduction ensures better placental adaptation and reduces risks of miscarriage.
After 14 weeks, risks of preterm labor and pregnancy loss increase.
A 32-year-old woman at 12 weeks gestation with a trichorionic triplet pregnancy opts for selective reduction. What is the preferred method for reducing the number of fetuses?
A. Intracardiac potassium chloride (KCl) injection
B. Fetoscopic laser ablation of placental vessels
C. Radiofrequency ablation (RFA)
D. Cord occlusion with umbilical clips
A. Intracardiac potassium chloride (KCl) injection
Rationale:
For triplets or higher-order pregnancies, KCl injection into the fetal heart is the standard method.
Laser ablation and RFA are typically used in monochorionic pregnancies with TTTS or TRAP.
Umbilical cord occlusion is used in later gestations (>16 weeks).
Twins with monochorionic placentation should be delivered when there are signs of maturity due to the risk of:
A. Cord entanglement
B. Twin-Twin Transfusion Syndrome (TTTS)
C. Preterm premature rupture of membranes (PPROM)
D. Intrauterine Growth Restriction (IUGR)
B. Twin-Twin Transfusion Syndrome (TTTS)
📌 Rationale:
MC twins are at risk for TTTS, which can occur at any point in pregnancy.
Prolonging pregnancy increases the risk of sudden fetal deterioration.
Delivery is typically planned between 34-36 weeks if there are no complications.
Cord entanglement is a risk only in monoamniotic (MCMA) twins, not all MC twins.
What is the recommended schedule for monitoring fetal weight estimate in twins?
A. Ultrasound every 3-4 weeks
B. Weekly ultrasounds from 16 weeks
C. Ultrasound only if fundal height is abnormal
D. Growth scans every 6 weeks
A. Ultrasound every 3-4 weeks
📌 Rationale:
Twins require regular ultrasound monitoring to assess growth discordance.
DC twins → Ultrasound every 4 weeks from 20 weeks onward.
MC twins → Ultrasound every 2 weeks from 16 weeks to check for TTTS.
What is the recommended maternal weight gain for a woman with a twin pregnancy and normal BMI?
A. 37 lbs (16-24 kg)
B. 25 lbs (11-12 kg)
C. 45 lbs (20 kg)
D. 50 lbs (23 kg)
A. 37 lbs (16-24 kg)
📌 Rationale:
Twin pregnancies require more weight gain than singletons for optimal fetal growth.
Recommended range: 16-24 kg (35-50 lbs), depending on pre-pregnancy BMI.
Underweight mothers may require even higher weight gain.
What does the lambda (λ) sign on ultrasound in the second trimester indicate?
A. Diamniotic dichorionic (DCDA) twins
B. Monochorionic diamniotic (MCDA) twins
C. Monochorionic monoamniotic (MCMA) twins
D. Conjoined twins
A. Diamniotic dichorionic (DCDA) twins
📌 Rationale:
Lambda (λ) sign = Thick dividing membrane → Suggests DCDA twins (each has its own placenta and amniotic sac).
T-sign = Thin dividing membrane → Suggests MCDA twins.
MCMA twins have no separating membrane.
Twins and other multiples are usually born preterm before 37 weeks. What is the average length of pregnancy for twin births?
A. 35 weeks
B. 37 weeks
C. 33 weeks
D. 38 weeks
A. 35 weeks
📌 Rationale:
Twins typically deliver at ~35-36 weeks, earlier than singletons (~40 weeks).
Monochorionic twins are delivered between 34-36 weeks.
Higher-order multiples (triplets, quadruplets) deliver even earlier.
Which of these nutrients is most important for mothers with twin pregnancies?
A. Iron and folate
B. Vitamin D and calcium
C. Protein and omega-3 fatty acids
D. Magnesium and zinc
A. Iron and folate
📌 Rationale:
Iron is needed to prevent anemia (higher risk in twin pregnancies).
Folic acid reduces neural tube defects and supports increased fetal demands.
Calcium and protein are also important, but iron and folate are most critical.