Chronicity & Amnionicity
The ultrasound sign in the 1st trimester that suggests dichorionic twins.
What is the lambda sign (twin peak sign)?
In monochorionic diamniotic twins, TTTS screening begins at this gestational age.
What is 16 weeks?
The TTTS staging system most commonly used clinically.
What is Quintero staging?
Complication unique to MO-MO Twins
What is cord entanglement?
A twin delivery should ideally occur in this location even when planning vaginal birth.
What is the operating room (OR) / OR-ready setting?
This ultrasound finding in the first trimester is the single strongest clue for monochorionicity.
What is the T-sign?
TTTS screening interval for monochorionic diamniotic twins.
What is every 2 weeks?
The Quintero stage at which referral is made for fetoscopic laser of placental anastomosis.
What is stage II?
In monochorionic twins, this complication is characterized by discordant MCA PSV with normal amniotic fluid volumes.
What is TAPS
After delivery of Twin A, the most important immediate next step before pushing for Twin B is to do this.
What is confirm Twin B presentation and fetal status (ultrasound + FHR)?
The term describing twins who are genetically identical but can still be dichorionic diamniotic.
What are monozygotic twins?
In uncomplicated dichorionic twins, growth ultrasounds are generally done at this interval starting in mid-2nd trimester.
What is every 4 weeks (starting ~20–24 weeks)?
Stage II is defined by these ultrasound finding.
What is oli/poly sequence and donor bladder not visualized?
The most common complication of twin pregnancy overall.
What is preterm birth?
The qualifications for breech extraction of Twin B.
What is:
-Fetus A is vertex
-EFW >1500g and <400g
-GA > 32 weeks
-Experienced clinician
The most accurate gestational age window to assign chorionicity by ultrasound.
What is 11–14 weeks?
The recommended delivery window for uncomplicated monochorionic diamniotic twins.
What is 34–37 weeks?
The gestational age when routine TTTS screening begins in MCDA twins.
What is 16 weeks?
The monochorionic complication where one twin has no functional heart and is perfused by the other twin.
What is TRAP sequence?
Timing of delivery for uncomplicated Mo-Di Twins.
What is 34-37 6/7 WGA?
The timing of zygote division that results in monochorionic diamniotic twins.
What is splitting between days 4–8 after fertilization?
The definition of selective fetal growth restriction in monochorionic diamniotic twins.
A detailed list of Quintero stages.
What is:
Stage I: oli poly
Stage II: Absent donor bladder
Stage III: Abnormal dopplers
Stage IV: Hydrops of one twin
Stage V: Death of one or both twins
The risk of neurologic injury and death with IUFD of co-twin.
What is 25%/15% for modi twins and 1%/3% for didi twins?
List of the common maneuvers for breech extraction.
What are Pinard (leg delivery), Lovset (arm delivery), and Mariceau-Smellie Veit (head delivery)?