น.พ. ธรีะ ทองสงภาควิชาสตูิศาสตรแ์ละนรเีวชวิทยา

คณะแพทยศาสตร ์มหาวิทยาลัยเชียงใหม่

2 sperms, 2 eggs

Incidence : variable

Fetal sex : same or different

Membranes : dichorionic, diamnionic

Placenta : one fused or two separate

Incidence : 1:250 pregnancies

Fertilization : 1 sperm, 1 egg

Fetal sex : same (except XO,XY)

Placenta : one fused or separate

(two separate : dichorionic)

Division of zygote : depend on day of twinning

Twin-specific Complication (%)

Type of TwinningTwins

(%)

Fetal Growth

Restriction

Preterm

Delivery

Placental

Vascular

Anastomosis

Perinatal

Mortality

Dizygotic 80 25 40 0 10-12

Monozygotic 20 40 50 15-18

-Diamnion/dichorion 6-7 30 40 0 18-20

-Diamnion/monochorion 13-14 50 60 100 30-40

-Monoamnion/monochorion <1 40 60-70 80-90 58-60

Conjoined Twins 0.002 -

0.008

— 70-80 100 70-90

History :

Weak : maternal family history, advanced maternal age,

high parity, large maternal size

Strong : recent clomiphene citrate or gonadotropins,

Assisted reproductive techniques (ART)

Clinical examination : size > date (2nd trimester)

Ultrasound : separate gestational sac, 2 head

or abdomen in the same plane

Chorionicity

Dichorion :

twin peak sign (lambda sign)

thick dividing membrane

(> 2 mm)

separate placenta

Monochorion :

T sign

Zygosity

genetic testing

sex

3500 kcal/day

Iron (60 mg/day)

Folic acid (1 mg/day)

Calcium (2000 mg/day)

TWG 16 – 20 kg at term

DM screening (as same as singleton)

Serial U/S in 2nd and 3rd trimester

Monochorionic twins every 2 – 3 wks in 2nd trimester

Dichorionic twin every 4 – 6 wks in 2nd trimester (or after 20 wks)

Frequent scans if FGR or growth discordance

Antepartum testing in uncomplicated twin No benefit

Indicated in IUGR

Discordant growth

Abnormal amniotic fluid volumes

Monoamniotic twins

Preeclampsia

NSTs or BPPs 1 – 2 weekly

Bed restIs often recommended for prevention of preterm labor

RCTs of hospitalization or bed rest in twin failed to prolong GA

Home uterine monitoringEffectively detects contractions predictive of preterm labor

There are no data that it improves neonatal outcome

Measurement of cervical lengthRoutine U/S for cervical length : not recommended

Fetal fibronectinRoutine fFN test of asymptomatic women : not recommended

CerclageRCT of prophylactic cerclage in twin : no benefit

Tocolytic drugsRoutine tocolysis for asymptomatic women : not effective

2 skilled OB attendants for labor and delivery

Anesthesiologist available at delivery

Neonatal care personnel

Portable ultrasound scanner

Reliable IV access

CTG with dual monitoring capability

Delivery bed with lithotomy stirrups

Forceps or vacuum

Oxytocin infusion

Tocolytic agent for uterine relaxation

Methergine, 15-methyl PGF2 alpha or both

Immediate availability of blood

Capabilities and staff for emergency C/S

Latent phase

Active phase

Epidural block

Hypotonic uterine dysfunction

Hypocontractility after delivery of first twin

Postpartum hemorrhage

Vertex-Vertex

Vertex-Nonvertex

Nonvertex

Vaginal delivery

Time interval between deliveries of twins

Fetal distress

Instrumental delivery (vacuum, forceps)

Internal podalic version

Cesarean section

Clamp umbilical cord of twin A

PV, U/S

A short period of uterine quiescence external manipulation of twin B if necessary

Oxytocin IV infusion to resume uterine contraction (if no contraction within 10 min)

Amniotomy when the head engage

Mean interval 21 min (2/3 interval < 15 min)

ACOG 1998 interval between delivery of twins is not critical in determining the outcome of 2nd twin

Umbilical cord blood gas deteriorate with increasing time interval

Maximum time limit of 30 min with documentation of reassuring FHR pattern

There is a clear, emergent OB indication

EFW > 1500 gm

Experienced operator

Available anesthesia for effective Uterine relaxation

Simultaneous preparation for emergency C/S

Vaginal delivery Breech extraction of 2nd twin (partial or total)

External cephalic version of 2nd twin

Cesarean delivery of 2nd twin

Cesarean delivery of both twins

Vaginal breech delivery of 2nd twin increase risk of mortality

C/S delivery is associated with the lowest rate of neonatal morbidity and mortality

Observational, non-RCT study : no increased risk of adverse neonatal outcome

Only 1 RCT prospective Maternal fever (11.1% vs 40.7%)

Postpartum hospitalization (4.9 vs 8 days)

Neonatal hospitalization (8.0 vs 13.1 days)

Success rate > 95%

Operator must be experienced in Vg breech delivery

Should be avoided ifEFW of Twin B > Twin A 500 gm

EFW of Twin B < 1500 gm

Emergency conditionsTotal breech extraction

C/S

An alternative for fetuses not appropriate for vaginal breech delivery

Literature review5 series reviewed, 118 patients

Successful Vg deliveries (58% vs 98% in breech extraction)

Complications (10% vs 1% in breech extraction)

Cord prolapse (5% vs 0.3% in breech extraction)

More likely to undergo abdominal delivery than breech extraction

Comparison of BE of 2nd twin, ECV of 2nd twin, C/S of both

Healthy newborn

BE > ECV and C/S

Ventilator requirement

C/S > ECV> BE

Length of stay

C/S > ECV> BE

Charges

C/S > ECV> BE

Vaginal breech extraction of nonvertex 2nd twin provides equivalent, if not superior, outcomes at a lower cost

Limited data to support C/S delivery

Transverse

Breech (EFW < 1500 or > 1500 gm)

Interlocking of fetal heads

Interference of 2nd twin on descent of 1st twin deflection of head

Inadequately dilate of cervix

ACOG recommends C/S delivery of a nonvertex presenting 1st twin

C/S does not eliminate the possibility of a technically difficult or traumatic birth

Type of uterine incision should be based on

Size and weight of twins

Skill of the operator

Degree of development of lower uterine segment

The worst of both worldsA tiring and often risky pregnancy

A tiring labor

A major abdominal operation

Two lots of stitches

Two new babies to care for

9.5%

Increase C/S rate, increase combined delivery

1/3 of vertex-nonvertex twin

No one intentionally plans a combined delivery

If – for whatever reason – safe vaginal delivery of twin B cannot be expected, no need to test one’s ability to handle cataclysmic situations

Premature twins

Prior cesarean

Vertex-Vertex

Vertex-Nonvertex

Increase perinatal asphyxia and birth trauma in very low birth weight twin with vaginal breech delivery

ACOG conclude that C/S of nonvertex 2nd twin EFW< 1500-2000 gmis an appropriate management option

Should not be an absolute contraindication to vaginal delivery of twins

Success rate 30-75%

Risk of uterine rupture is the same as VBAC in singleton

Twin A VertexTwin B Vertex

Twin A VertexTwin B Nonvertex

Twin A Nonvertex

EFW > 1500 g EFW < 1500 g

Twin B > 500 g larger than twin AContraindication to Vg breech delivery

Twin A; Vx Vg deliveryTwin B; Br Vg delivery C/S both twinsIntrapartum ECV

Success Unsuccess

Vx Vg delivery of both twins

Combined Vg-C/S delivery

C/S of both twinsVg delivery of both twins