Multifetal gestation and malpresentation

Question 1

Monozygotic twins- placenttion

Answer 1

depends on time of cleavage

• Dichorionic, diamniotic- 0-3 days
• Monochorionic, diamniotic- 4-8 days
• Monochorionic, monoamniotic- 9-12 days
• conjoined twins- > 13 days

Question 2

Dichorionic diamniotic

Answer 2

• 0-3 days cleavage
• 2 chorions, 2 anions
• 30% of monozygotic twins

Question 3

Monochorionic diamniotic

Answer 3

• 4-8 days cleavage
• 1 chorion, 2 amnions
• 69% of monozygotic twins

Question 4

Monochorionic monoamniotic

Answer 4

• 9-12 days of cleavage
• 1% of monozygotic twins
• most dangerous- cord entanglement
• net mortality 50-80%

Question 5

Monochorionic monoamniotic- conjoined twins

Answer 5

• 13-15 days of cleavage
• craniopagus- joined at cranium
• thoracopagus- joined at chest wall
• ischopagus- joined by coccyx and sacrum

Question 6

confirmation of multiples by?

Answer 6

US

Question 7

most important step after dxing twins

Answer 7

• determination of zygosity
• monozygotic
• dizygotic

Question 8

US to determine zygosity

Answer 8

• dizygotic- diff fetal gender, thick amnion-chorion septum, peak or inverted V sign at base of septum
• monozygotic- dividing membrane is thin
• if US is not definitive- inspect placenta after delivery, DNA analysis

Question 9

abnormalities in monozygotic twins- Interplacental vascular anastomoses

Answer 9

• 90% occur in monochorionic twins

- abortion, polyhydramnios, TTTS, fetal malformations

Question 10

abnormalities in monozygotic twins- TTTS (twin twin transfusion syndrome)

Answer 10

• anastomses in monochorionic placenta- blood flow from 1 twin to the other
• donor twin- hypovolemia, hypotension, anemia, oligohydramnios, growth restriction
• recipient twin- hypervolemia, polyhydramnios, thrombosis, HTN, polycythemia, edema, CHF
• both at risk for HF

Question 11

TTTS- dx

Answer 11

US

• donor twin- smaller, “stuck”, oligohydramnios
• recipient twin- larger, polydyramnios, ascites

Question 12

TTTS- tx

Answer 12

• amniocentesis with amniotic fluid reduction

- laser photocoagulation of anastomosis vessels on placenta

Question 13

abnormalities in monozygotic twins- Arterial to Arterial anastomoses

Answer 13

• can cause thrombosis
• recipient twin (perfused with poorly deoxygenated blood) fails to develop normally- ACARDIAC twin- no anatomic structures cephalad of abdomen

Question 14

abnormalities in monozygotic twins- Umbilical cord abnormalities

Answer 14

• absence of umbilical a

- velamentous umbilical cord insertions occur more freq- may cause growth abnormalities

Question 15

abnormalities in monozygotic twins- retained dead fetus syndrome

Answer 15

• if gestation is > 20 wks
• DIC in mother
• check plts and fibrinogen levels weekly
• if gestation is < 12 wks- dead fetus is reabsorbed- vanishing twin syndrome
• if > 12 wks- fetus shrinks, dehydrates- fetus papyraceus

Question 16

Monoamniotic twins- should be delivered when

Answer 16

• 32 wks

- due to inc risk of lethal cord entanglement

Question 17

majority of twin gestations deliver when

Answer 17

35-36 wks

Question 18

Vertex-Vertex presentations

Answer 18

• presenting twin is twin A
• 40-50% of time
• 2nd twin at risk of cord prolapse, placental abruption, malpresentation
• risk of postpartum hemorrhage (uterine atony)

Question 19

breech-breech and breech-vertex- delivered via?

Answer 19

c-section

Question 20

perinatal mortality due to

Answer 20

• RDS and intracranial hemorrhage

- birth asphyxia- second twins have 2x mortality

Question 21

fetal malpresentation

Answer 21

• breech- most common!
• face
• brow
• shoulder
• compound

Question 22

breech presentation

Answer 22

• fetal buttocks or LEs presents into maternal pelvic
• 4% of all deliveries
• factors assoc- prematurity (most common), fetal malformations, mult pregnancies, uterine malformations
• dx- leopolds maneuver, US, pelvic exam

Question 23

breech presentations- classifications

Answer 23

• Frank (65%)- most common- thighs flexed, LEs extended at knees
• Complete (25%)- thighs flexed, LEs flexed
• Incomplete (10%)- 1 or both thighs extended, 1 or both feet below buttocks

Question 24

External Cephalic Version (ECV)

Answer 24

• apply pressure to mother’s abdomen to turn fetus in a fwd or backward somersault to achieve a vertex presentation
• 36 wk gestation not in labor
• contraindications- placental previa, non reassuring fetal monitoring, oligohydramnios, prev uterine surgery
• performed when ready to perform an immediate c-section!!

Question 25

deliver breech how?

Answer 25

most places do c-section

Question 26

assisted breech vaginal delivery

Answer 26

• allow fetus to deliver to scapulae (premature traction can cause head entrapment, nuchal arm entrapment)
• external rotation of each thigh and opp rotation of fetal pelvis- delivery of leg
• wrap towel around fetus for traction
• piper forceps

Question 27

brow presentation

Answer 27

• presenting part is b/w facial orbits and anterior fontanelle
• diameter- supraoccipitomental diameter
• most convert to a face presentation or vertex presentation and then deliver
• delivery by c-section

Question 28

face presentation

Answer 28

• full extension of fetal head and neck with occiput against upper back
• 60% present mentum anterior- can deliver vaginally
• can NOT deliver vaginally if mentum posterior presentation

Question 29

compound presentation

Answer 29

• fetal extremity (usually hand) is found prolapsed alongside the presentation fetal part (heaD)
• may resolve on its own
• c-delivery if failure to progress, cord prolapse, or non reassuring fetal status