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Questions and Answers
Which of the following describes an acardiac twin condition?
Which of the following describes an acardiac twin condition?
- Both twins developed normally.
- An amorphous mass with no developed parts. (correct)
- Only the lower part developed. (correct)
- Both twins are acephalous.
Interlocking of twins occurs in the second twin.
Interlocking of twins occurs in the second twin.
False (B)
What is the typical management for conjoint twins?
What is the typical management for conjoint twins?
C-section at 32-34 weeks
Fetal weight in IUGR is defined as less than the __________ percentile of a normal fetus.
Fetal weight in IUGR is defined as less than the __________ percentile of a normal fetus.
Match the type of twin complication with its description:
Match the type of twin complication with its description:
What does PTL stand for in medical terms?
What does PTL stand for in medical terms?
The beginning of preterm labor occurs after 37 weeks of gestation.
The beginning of preterm labor occurs after 37 weeks of gestation.
What is the primary characteristic of preterm labor?
What is the primary characteristic of preterm labor?
Preterm labor is defined as when the process of labor begins at __________ weeks of gestation.
Preterm labor is defined as when the process of labor begins at __________ weeks of gestation.
Match the following terms related to labor with their definitions:
Match the following terms related to labor with their definitions:
What does fetal fibronectin act as between the fetal membrane and decidua?
What does fetal fibronectin act as between the fetal membrane and decidua?
Fetal fibronectin is usually present in cervicovaginal secretions before 22 weeks of gestation.
Fetal fibronectin is usually present in cervicovaginal secretions before 22 weeks of gestation.
What are the two conditions associated with the presence of fetal fibronectin between 22-35 weeks?
What are the two conditions associated with the presence of fetal fibronectin between 22-35 weeks?
Four contractions in 20 minutes or eight contractions in 60 minutes are part of the current definition of __________.
Four contractions in 20 minutes or eight contractions in 60 minutes are part of the current definition of __________.
Match the following definitions with their associated symptoms:
Match the following definitions with their associated symptoms:
What is the primary purpose of Doppler studies in twin pregnancies?
What is the primary purpose of Doppler studies in twin pregnancies?
Oligohydramnios refers to an excessive amount of amniotic fluid.
Oligohydramnios refers to an excessive amount of amniotic fluid.
What is the recommended treatment for twin pregnancies diagnosed before 28 weeks?
What is the recommended treatment for twin pregnancies diagnosed before 28 weeks?
The condition known as TAPS is a milder, chronic form of ________.
The condition known as TAPS is a milder, chronic form of ________.
Match the following conditions with their descriptions:
Match the following conditions with their descriptions:
Which of the following is a maternal complication associated with twin pregnancy?
Which of the following is a maternal complication associated with twin pregnancy?
Intrahepatic cholestasis is a known complication that can occur in twin pregnancies.
Intrahepatic cholestasis is a known complication that can occur in twin pregnancies.
What is the recommended prophylaxis for pre-eclampsia in twin pregnancy?
What is the recommended prophylaxis for pre-eclampsia in twin pregnancy?
The risk of preterm labor is increased in twin pregnancies due to __________.
The risk of preterm labor is increased in twin pregnancies due to __________.
Match the following fetal complications with their characteristics:
Match the following fetal complications with their characteristics:
What is the maximum time gap allowed between the deliveries of twins?
What is the maximum time gap allowed between the deliveries of twins?
Vaginal delivery is always possible for both twins.
Vaginal delivery is always possible for both twins.
What delivery method is indicated if the second twin is in a transverse position and there is a prior history of C-section?
What delivery method is indicated if the second twin is in a transverse position and there is a prior history of C-section?
Methyl ergometrine is contraindicated after the delivery of the __________ twin.
Methyl ergometrine is contraindicated after the delivery of the __________ twin.
Match the delivery presentations with their corresponding delivery methods:
Match the delivery presentations with their corresponding delivery methods:
What is the primary method for assessing amniotic fluid in a twin pregnancy?
What is the primary method for assessing amniotic fluid in a twin pregnancy?
Oligohydramnios refers to increased amniotic fluid in one twin.
Oligohydramnios refers to increased amniotic fluid in one twin.
What condition is indicated when bladder visualization is normal in a twin with oligohydramnios?
What condition is indicated when bladder visualization is normal in a twin with oligohydramnios?
The _____ system is activated in the donor twin during TTTS to maintain blood pressure and volume.
The _____ system is activated in the donor twin during TTTS to maintain blood pressure and volume.
Match the stages of TTTS to their characteristics:
Match the stages of TTTS to their characteristics:
What is the optimal timing for cervical cerclage surgery during pregnancy?
What is the optimal timing for cervical cerclage surgery during pregnancy?
Progesterone can prevent preterm labor once uterine contractions have started.
Progesterone can prevent preterm labor once uterine contractions have started.
What cervical length measured by transvaginal ultrasound is an indication for cervical cerclage?
What cervical length measured by transvaginal ultrasound is an indication for cervical cerclage?
Hydroxyprogesterone caproate is administered via __________ injections, starting at 16-20 weeks gestation.
Hydroxyprogesterone caproate is administered via __________ injections, starting at 16-20 weeks gestation.
Match the medication to its method of administration:
Match the medication to its method of administration:
What is a complication that occurs specifically in monochorionic twins?
What is a complication that occurs specifically in monochorionic twins?
TTTS is more prevalent in DCDA twins compared to MCDA twins.
TTTS is more prevalent in DCDA twins compared to MCDA twins.
What is the primary physiological change in the donor twin affected by TTTS?
What is the primary physiological change in the donor twin affected by TTTS?
In Selective IUGR, the affected twin is typically known as the __________ twin.
In Selective IUGR, the affected twin is typically known as the __________ twin.
Match the following characteristics with the appropriate twin in TTTS:
Match the following characteristics with the appropriate twin in TTTS:
What is a common complication for twin pregnancies?
What is a common complication for twin pregnancies?
Vanishing twin syndrome occurs more commonly in singleton pregnancies than in twin pregnancies.
Vanishing twin syndrome occurs more commonly in singleton pregnancies than in twin pregnancies.
What complications can arise due to vascular anastomosis in surviving monochorionic twins?
What complications can arise due to vascular anastomosis in surviving monochorionic twins?
In monochorionic twin pregnancies, congenital anomalies are more prevalent due to __________.
In monochorionic twin pregnancies, congenital anomalies are more prevalent due to __________.
Match the following conditions related to twin pregnancy with their descriptions:
Match the following conditions related to twin pregnancy with their descriptions:
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Study Notes
Fetal Fibronectin Protein
- Present between fetal membrane and decidua
- Acts as glue and present in cervicovaginal secretions
- Normal after 35 weeks
- Suggests PTL or PROM between 22-35 weeks
Preterm Labor (PTL) Definition
- Uterine contraction defined as 4 contractions in 20 mins/ 8 contractions in 60 mins
- One of the following criteria must be met:
- Progressive dilatation and effacement of cervix
- Cervical dilatation at initial presentation
Acardiac Twin Outcome
- Acardiac acephalus: Only the lower body of twin develops
- Acardiac amorphous: No parts develop, forming an amorphous mass
Selective IUGR
- Normal twin is represented by circle "A" in the diagram
- IUGR twin represented by circle "B" in diagram
- Fetal weight < 10th percentile of normal fetus
-
25% discordance in weight compared to normal twin
Monoamniotic Twin Complications
- Cord entanglement:
- Cause: Formation of true knots
- Conjoint twins: :
- Management: C-section at 32-34 weeks
Twin Pregnancy Delivery
- First twin is closer to internal os during pregnancy
- First twin comes out first during delivery
- Most common presentation: Both twins vertex
- 1st twin vertex & second twin breech can result in interlocking of twins
- Interlocking of twins seen in first twin and managed via C-section
Doppler Studies
- Performed at 16-20 weeks
- Include umbilical artery, vein, and ductus venosus
- PSV of MCA
Ultrasound in Twin Pregnancy
- Fetal biometry for growth assessment
- Diagnose oliguria/polyhydramnios
- Diagnose hydrops fetalis
Recipient Twin Echocardiography
- Assess for pulmonary atresia/stenosis
- Hypertrophy
- Right side dysfunction
- Left side dysfunction
Interventions for Twin-to-Twin Transfusion Syndrome (TTTS)
- ≤ 28 weeks: Fetoscopic laser ablation of vascular anastomosis
- > 28 weeks: Serial amnioreduction
Twin Anemia Polycythemia Syndrome (TAPS)
- Atypical, milder, chronic form of TTTS
- Caused by slow transfusion of RBCs via few, small vessels
- Hemoglobin levels:
- Donor twin: ≤ 1.5 mom (months)
- Recipient twin: < 0.8 mom (months)
Twin Reversed Arterial Perfusion (TRAP)
- Rare monochorionic twin complication
- Deoxygenated blood flows from normal twin (Twin A) to acardiac twin (Twin B)
- Flow via aberrant arterio-arterial anastomosis
Maternal Complications of Twin Pregnancy
- Pronounced haemodynamic changes
- Pre-eclampsia
- Abruptio Placenta
- Placenta previa
Other Maternal Complications
- ↑ Placenta size
- Intrahepatic cholestasis and acute fatty liver of pregnancy
- ↑ Human placental lactogen
- Polyhydramnios:
- ↑ risk of: Preterm labor, PROM, Postpartum hemorrhage, Cord prolapse, malpresentations
- Hyperemesis gravidarum
- Gestational diabetes
- ↑ hCG
Fetal Complications
- Most common in:
- Monochorionic vs. dichorionic twins
- Monozygotic vs. dizygotic twins (Exception: Cumulative risk of chromosomal anomalies)
Testing for Aneuploidy
- Monozygotic: Sample from any twin
- Dizygotic: Sample from both twins
Fetal Reduction
- DOC: Intracardiac KCl injection
- Given to fetus with least chance of survival
- Timing: 10 - 13 weeks
- Does not affect survival of the other fetus
Amniotic Fluid Assessment
- Single largest vertical pocket on ultrasound is best method for assessing amniotic fluid.
TTTS Diagnostic Criteria
- MCDA: Monochorionic diamniotic twins with TTTS
- Polyhydramnios in one twin
- Oligohydramnios in the other twin
- Early marker: Increased nuchal translucency
- Stuck twin: Activation of RAAS in donor twin
Quintero Staging for TTTS
| Stages | One Twin | Other Twin | Doppler Findings |
|---|---|---|---|
| Stage 1 | Polyhydramnios | Oligohydramnios: Bladder visible (oliguria) | Normal |
| Stage 2 | Polyhydramnios | Oligohydramnios: Bladder not visible (anuria) | Normal |
| Stage 3 | Abnormal doppler study | ||
| Stage 4 | Hydrops fetalis in one/both twins | ||
| Stage 5 | Death of one/both twins |
Delivery Options Based on Presentation
| 1st Twin | 2nd Twin | |
|---|---|---|
| Presentation | Vertex | Vertex |
| Breech | Transverse | |
| Delivery | Vaginal delivery | Vaginal delivery |
| Vertex | ||
| Breech | Assisted breech delivery | |
| Shift to OT Internal podalic version + breech extraction | ||
| Transverse | ||
| C-section | C-section |
Additional Notes
- After delivery of 1st twin: methyl ergometrine is contraindicated (causes uterine contractions)
- Maximum time gap between twin deliveries: 30 minutes
- If time gap exceeds 30 minutes, immediate C-section for second twin is performed
- Internal podalic version: Performed if the 2nd twin is in transverse lie
- Only indication if there’s a previous history of a C-section
- Method of delivery is under general anesthesia
- External cephalic version: Only performed if the membranes are intact
General Twin Pregnancy Complications
- Preterm labor
- IUGR
- Congenital anomalies
Cervical Cerclage
- Not recommended in primigravida
- Not recommended if no history of preterm labor or 2nd trimester abortion in twin pregnancy
- Indications:
- History of preterm birth
- Cervical length ≤ 2.5 cm
- Singleton pregnancy
- Timing: 14-24 weeks gestation
- Additional: Progesterone given with the cerclage.
Progesterone
- Indications: History of preterm labor
- Medications:
- Hydroxyprogesterone caproate: Intramuscular (IM) weekly injections, start 16-20 weeks, stop at 36 weeks
- Micronised progesterone: Per vaginally daily
- Function: Smooth muscle relaxant
PTL: Important Note
- Progesterone cannot prevent PTL once uterine contractions have started
PTL: Additional Considerations
- Symptoms: Uterine contractions (4 contractions in 20 minutes / 8 contractions in 60 minutes) AND any of the following:
- Cervical length ≤ 2 cm
- Cervical dilation ≥ 3 cm
- Positive fetal fibronectin protein test (≥50 ng/mL) in cervicovaginal secretions.
Diagnostic Procedures
- Pelvic Exam (speculum): Rule out premature rupture of membranes (PROM)
- Pelvic Exam (vaginal):
- If cervical dilation is ≥ 3 cm → refer to labor and delivery
Congenital Anomalies
- Twin > singleton pregnancy
- Monochorionic > dichorionic twins
- Heart defects: TTTS (Twin-to-twin transfusion syndrome) - monochorionic twins
- Diagnosis methods:
- Echocardiography (18-22 weeks)
- Targeted/Anomaly/Level II scan
- Diagnosis methods:
Vanishing Twin
- Early spontaneous reduction in twin pregnancy
- Common in IVF pregnancies
- Effect on other twin: Normal survival ± LBW (low birth weight)/SGA (small for gestational age)
Death of One Twin
- Surviving monochorionic twin: Complications d/t vascular anastomosis
- Surviving dichorionic twin: Complications d/t absence of vascular anastomosis
Monochorionic Twin Complications
- High pressure system: Twin A
- Hypotension
- Anemia
- Exsanguination
- Low pressure system: Twin B
Death of Twin A
- Diagram Description: A diagram depicts the pathway of blood flow from the healthy twin (Twin A) to the dying twin (Twin B) in a monochorionic pregnancy. It shows the consequence of this blood flow, such as the high blood pressure in Twin A and low blood pressure in Twin B.
Management
- Immediate delivery: Not indicated
- Note: Pregnant female with USG showing impending death of 1st twin
Specific Monochorionic Twin Complications:
- TTTS (Twin to twin transfusion syndrome)
- TAPS (Twin anemia polycythemia sequence)
- Immediate delivery of both twins
- TRAP (Twin reverse arterial perfusion)
- Selective IUGR
IUGR vs Selective IUGR
| IUGR | |
|---|---|
| Related to number of twins | |
| A | |
| IUGR | |
- Selective IUGR:*
- Complication of monochorionic twins.
Twin to Twin Transfusion Syndrome (TTTS)
- Etiopathogenesis: Occurs due to deep vascular anastomosis between artery and vein.
- Prevalence: MCDA: Most common (due to deep anastomosis)
- MCMA: Less common (due to superficial anastomosis)
- DCDA: Not seen (vascular connections Θ)
TTTS: Factors
| Donor | Recipient | |
|---|---|---|
| Renal blood flow | ↓ (↑ risk of renal failure) | ↑ |
| GFR | ↓ | ↑ |
| Amniotic fluid | Oligohydramnios | Polyhydramnios |
| Hemoglobin levels | Anemia | Polycythemia |
| Peak systolic volume (PSV) of middle cerebral artery (MCA) |
TTTS: Complications
| Donor | Recipient | |
|---|---|---|
| Heart failure | Congestive heart failure | |
| ≥1.5 mom | < 0.8 mom | |
| Hydrops fetalis | ||
| Death |
Measures to Prevent Preterm Labor (PTL)
Cervical Cerclage Surgery
- Indications:
- History of preterm birth (H/O PTL)
- Cervical length ≤ 2.5 cm (measured by transvaginal ultrasound (TVS))
- Singleton pregnancy
- Timing: 14-24 weeks gestation
- Additional: Progesterone should be given with the cerclage.
Progesterone
- Indications: H/O PTL
- Medications:
- Hydroxyprogesterone caproate: IM weekly injections, start 16-20 weeks, stop at 36 weeks
- Micronised progesterone: Per vaginally daily
- Function: Smooth muscle relaxant
Important Note
Progesterone cannot prevent PTL once uterine contractions have started
Other Considerations
- Symptoms: Uterine contractions (4 contractions in 20 minutes / 8 contractions in 60 minutes) AND any of the following
- Cervical length ≤ 2 cm (measured by TVS)
- Cervical dilation ≥ 3 cm
- Positive fetal fibronectin protein test (≥50 ng/mL) in cervicovaginal secretions.
Diagnostic Procedures
- Pelvic Exam (speculum): Rule out premature rupture of membranes (PROM)
- Pelvic Exam (vaginal): If cervical dilation is ≥ 3 cm → refer to labor and delivery
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