Multiple pregnancy

Definition

One or more fetus developing in-utero.

Monozygotic

Twin resulted from fertilisation of a single ovum by one sperm.
The time when the separation of the zygote occurs decides the no. of placenta and amniotic sac.


If separation occurs within 72 hours -> Diamniotic Dichorionic
If separation occurs within 4-8 days -> Diamniotic Monochorionic
If separation occurs within 8-14 days -> Monoamniotic Monochorionic
If separation occurs after 14 days (embryonic pole has formed) -> Conjoined twins

Dizygotic twins

Twins resulted from fertilisation of 2 ovum by 2 sperms.
These twins are only of fraternal resemblance to one another.

Comparison in between Monozygotic and Dizygotic twins


 
History taking

Incidence of twin pregnancy increases with maternal age and parity
Is the current conception assisted? (IVF? Intake of any ovulation stimulatory drugs, eg: clomiphene)
Discontinuation of long term intake of OCP?
Family history of twins -> maternal side?

Excessive Nausea and Vomiting during early trimester
Cardiorespiratory discomfort during late trimester
Undue enlargement of abdomen
Worsening varicose veins and haemorrhoids

Examination

Anemia, edema, high BP, and abnormal weight gain
Clinical fundal height > Expected for the period of gestation
2 or more fetal head palpable
3 or more fetal pole palpable
2 distinct heard sounds, appreciated by 2 observers, with at least difference in 10 bpm

Confirmed by ultrasonography

Note that twin peak sign is best demonstrated during 9-10 week of gestation, which indicates dichorionicity.
It's important to determine the chorionicity during early pregnancy since the risk associated with monochorionic twins is greater than dichorionic twins.

Maternal risks

Increased risk of miscarriage
Severity of minor ailments in pregnancy increases
Increased symptoms of early pregnancy
Increased risk of Preterm labour
Anemia
Pregnancy-induced hypertension
Polyhydramnios
Antepartum haemorrhage (placenta praevia, or accidental haemorrhage)
PPH (uterine over-distension)
Malpresentation, especially the 2nd twin (cord prolapse, early rupture of membrane)

Fetal risks

1) Prematurity

Prematurity is the most common problem in twins pregnancy due to high incidence of pre-term labour.
Uterine overdistension, intrauterine infections and polyhydramnios are among the major causes of pre-term labour

2) Complications unique to monochorionic twins

a) Twin-to-twin transfusion syndrome

This condition arises due to abnormal uteroplacental vascular anastomosis.
One twin is receiving more blood supply -> Recipient twin
One twin is receiving less blood supply -> Donor twin

The recipient twin -> polyhydramnios, big size, may develop congestive cardiac failure
The donor twin -> oligohydramnios, small size, may develop high-output cardiac failure

Mortality rate in TTTS is about 60-70%
Associated with high risk of pre-term labour (hence corticosteroids must be administered as early as possible)
And higher risk of neurological abnormalities (cerebral palsy)

b) Discordant twins

Difference in weight in between 2 twins, usually noticed after 24 weeks of gestation.
Common causes : genetic syndromes and unequal placental masses

c) Acardiac twining

This condition is relatively rare.
Heart is not developed in one twin, and hence, circulation in both twins is maintained only by 1 heart.
Risk of high-output cardiac failure.

3) Fetal demise

If one twin dies in-utero <14 weeks of gestation, it's not going to affect the survival of another twin.

However, if it occurs >14 weeks of gestation, due to the release of thromboplastin from the dead twin, it's going to occlude the anterior/middle cerebral artery of the living twin, causing multicystic encephalomalacia.

On the other hand, mother is also at high risk developing DIVC.

In such scenarios, it's better to deliver the twins after 30 weeks of gestation.

4) Congenital anomalies

Congenital anomalies is more common among twins with identical gender and those of monochorionicity.
Cardiac and neurological defects are the commonest.

5) Conjoined twins

Incidence of conjoined twins is 1 in 200 pregnancies.
Prognosis will largely depends on the type of conjoined twins, and the feasibility of the operation to separate them.

Commonest is Thoracophagus, followed by Omphalophagus, Pyophagus, Ishiophagus, and lastly Craniophagus.

Antenatal management

3 aims in management :

Prevention of pre-term labour
Monitoring of fetal biometry
Optimum mode of delivery

Doses of supplements given must be increased, since the demand now is higher.

Frequency of antenatal visits must be increased, every 2 weeks (early detection of anemia or pre-eclampsia)

Elective hospitalisation for bed rest, to improve uteroplacental blood flow, suppress any heightened uterine activity, and to reduce pressure over cervix.

Any urinary and genital tract infections must be treated aggressively.

If there's a high risk of preterm labour, administer corticosteroids for early maturation of fetal lungs.

Intrapartum management

During labour, multiple pregnancy should be ideally managed in a tetiary health centre, with anasthesia services and intensive neonatal unit.

a) Mother should be kept nil by mouth (chances of operative delivery is high)
b) Maintained hydration and nutrition by IV drip
c) Continuous fetal monitoring

Internal CTG for the 1st twin
External CTG for the 2nd twin

d) Pain relief by epidural analgesia
e) Blood grouping and cross matching (anticipation of PPH)
f) Liason with pediatricians

Indications for LSCS in twin pregnancy

Presentation of 1st twin is not cephalic
Conjoined twins
Monoamniotic twins
IUGR in dichorionic twins
Chronic TTTS
Fetal anomalies
Contracted pelvis
Previous LSCS
Severe pre-eclampsia

Indications for emergency LSCS in twin pregnancy

Cord prolapse
Fetal distress
Failed version during 2nd twin delivery
Collision of twins
Prolonged labour

The first twin is delivered by normal vaginal delivery (if criteria is full-filled)
After cord clamping, and division, delivery of 2nd twin starts.


Ideal time to deliver the 2nd twin is 20-30 minutes time.

First, abdominal examination is done to determine the fetal lie.
Vaginal examination to determine the membrane status and to watch out of cord prolapse.

If it's transverse lie :

Attempt external cephalic version (prior and after ECV, CTG should be monitored for fetal distress)
If failed, rupture the membrane and attempt an internal podalic version under GA
Still fails, emergency LSCS

If the lie is longitudinal, if the presenting part is deeply engaged, perform amniotomy.
If there's uterine inertia (may be due to weak contractions after delivery of 1st twin, continuous oxytocin infusion is required - 5-10 IU of pitocin IV infusion)

In case there's fetal distress, or excessive vaginal bleeding (indicating placental abruption), either ventouse or outlet forceps delivery/emergency LSCS indicated for vertex presentation, and breech extraction or assisted breech delivery/emergency LSCS for breech presentation.

During 3rd stage to prevent PPH

After delivery of the anterior shoulder of the 2nd twin, 0.25 mg of ergometrine followed by 0.2 mg of methyl-ergometrine is given to the mother IM injection.

Placenta to be delivered via controlled-cord traction.
After delivery of placenta :

Continuous uterine massage
IM carboprost should be given

Locking of the twins

It's a relatively rare condition, where one twin is preventing the descent and delivery of another twin. There are 4 varieties of this condition :

a) Collision

The fetal parts of one twin is in contact with another twin, preventing it's descent. and hence engagement for both.

b) Impaction

The fetal parts of one twin is indenting with another twin, only allowing partial engagement of presenting part.

c) Compaction

The presenting part of both twins is engaged into the maternal pelvis simultaneously.

d) Interlocking of twins

Adhesion occurs in between the inferior surface of the chin of one twin with the other, either above or below the pelvic inlet.

Category: Obstetrics Notes