Twins & higher multiple gestations

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Is it good NEWS to be told that you are going to have twins?

Definition

Multiple pregnancies consists of two or more fetuses ,there are exceptions to this such as twins gestations made of a singleton viable fetus & a complete mole.

Prevalence

Twins account for approximately 1.5%

Higher multiple occur in 1/2500

Risk factors

1- assisted reproductive techniques (IVF& induction of ovulation )

2-high parity

3- black race

4- maternal family history

5- increasing maternal age.

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Hellin`s rule

Twins were expected in 1/80

Triple (1/80)2

Classification

1- according to number of fetuses

2-number of fertilized eggs

3-number of placentas ( chorionicity)

4-number of amniotic cavities (amniocity)

Non identical twins( dizygotic twins)

*Always have two separate placentas (DC)

*separate amniotic cavities (DA)

*the fetuses either the same or different sex pairing

Identical twins (monozygotic)

Arise from fertilization of single egg

Always of same sex

Either MC or DC

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The vast majority of MC are DA

Not all dichorionic are dizygotic

All monochorionic pregnancy are monozygotic

Aetilogy

Dizygotic twins may arise spontaneously from the release of two eggs at ovulation

Causes

Familial

Racial

Increasing maternal age

Induction of ovulation

IVF

Monozygotic twins

Arise from a single fertilized ovum that splits into two identical structures

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Types of monozygotic twins

When the split occur within 3 days of conception , two placentas &two amniotic cavities result (DC,DA)

When splitting occur between 4-8 days ,monochorionic diamniotic twins will result (MC,DA)

Later splitting results in two fetuses in a single amniotic cavity sharing single placentas (MC.MA)

If splitting delayed beyond 12 days , conjoined or Siamiese twins will result

The incidence of monozygotic twins 1/250 it is not influence by race ,family history or parity.

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MONOZYGOTIC TWINS

70% are diamniotic monochorionic.30% are diamniotic dichorionic.

Results from division of fertilized egg:

0-72 H. Diamniotic dichorionic.

4-8 days Diamniotic monochor.

9-12 days Monoamnio.monochor.

>12 days Conjoined twins.

Conjoined twins or Siamese twins

*Anterior (thoracopagus)*Posterior (pygopagus)*Cephalic (craniopagus)*Caudal (ischiopagus)

Maternal Physiological Adaptation

Increase blood volume and cardiac output.

Increase demand for iron and folic acid.

Maternal respiratory difficulty.

Excess fluid retention and edema.

Increase attacks of supine hypotension.

Complications of pregnancy

1- preterm labour

2-pregnancy-induced hypertension

3-anaemia

4-polyhydramnia

5-congenital malformation

6- growth restriction

7-miscarriage

8- high perinatal mortality & morbidity

Complication of labour

1-malpresentation

2-postpartum haemorrhage

3-cord prolapse

4- locked twins

In monochorionic twins death of one fetus may result in immediate complications in the survivor (brain damage ,death, neurodevelopment handicap)

Acute hypotensive episodes secondary to placental vascular anastamosis between the two fetuses result in haemodynamic volume shifts from the life to the dead fetus.

Fetal abnormalities

The risk of fetal abnormalities carry at least twice the risk in twins pregnancy

*In each DC twins the risk of structural abnormalities ,such as spina bifida is similar to that for singleton pregnancy

*Each MC twins carries the risk 4 X that of singleton pregnancy

Multiple gestations with an abnormality in one fetus can be managed expectantly or by selective fetocide of the affected fetus

1-When the abnormality is not lethal the parents should outweighs the risk of loss of a normal fetus from fetocide related complications

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When the abnormality is lethal it may better to avoid such risk to the fetus

In MC twins selective fetocide is dangerous for the second twins so they do cord occlusion techniques, these require significant instrumentation of the uterus & are therefore associated with higher complications.

Chromosomal defects & twining

1-monozygotic twins are affected either both or non of the twins will be affected ( the risk is based upon maternal age)

2- in DZ twins the risk will be twice that of singleton pregnancy ( e.g. the risk of Down syndrome 1/50)

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Complications unique to monoamniotic twins is cord accident

Differential diagnosis of twin pregnancy

1-polyhydramnious

2-big baby

3-ovarian cyst or mass

4-uterine fibroid

5-retntion of urine.

TWIN-TWIN transfusion

Chronic shunt occurs ,the donor bleeds into the recipient so one is pale with oligohydraminose while the other is polycythemic with hydraminose.

If not treated death occurs in 80-100% of cases.

Complications unique to monochorionic twins

Twin twin transfusion syndrome

Either mild , moderate or sever depends on the degree of imbalance

the donor fetus suffers from

1- hypovolaemia & hypoxia

2-growth restricted

3- oliguric

4-oligohydramnious

The recipient fetus suffers

1-hyprrvolaemic

2-polyhydraminous

3- myocardial damage

4- high output failure

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Sever disease appear at18-24w

Mother complain of

1- sudden increase in abdominal girth.

2- extreme discomfort

3- polyhydramnious (detcted by US)

90% of TTTS end in miscarriage or preterm labour due to polyhydramnious or death of one fetus.

Treatment

*Amniocentesis every 1-2w

*fetoscopically guided laser coagulation to disrupt the placental blood vessels that connect the circulation of the two fetuses

Other Complications in Monochorionic Twins:

Congenital malformation. Twice that of singleton.

Umbilical cord anomalies. In 3 4 %.

Conjoined twins. Rare 1:70000 delivaries. The majority are thoracopagus.

PNMR of monochorionic is 5 times that of dichorionic twins(120 VS 24/ 1000 births)

Diagnosis of Multiple Fetuses

History.

Clinical Examination.

Investigations.

History ovulation inducing drug

Family history of twin

Exaggerated symptoms

Cardiopulmonary embarrassment

Excessive fetal movement

General examination

Anaemia more than single pregnancy

Unusual weight gain

Evidence of PET ( 25% more)

Per abdominal examination

Height of the uterus more than the period of gestation

Too many fetal parts

Two fetal head

Two distinct fetal heart sound, at separated spot, provided the difference at least 10 beats per minute

Lab Investigation

Ultrasonography

Two gestational sacs can be detected as early as 10 weeks of pregnancy

Radiography

Should be done after 30 weeks

Management

Antenatal.

In Labor.

Antenatal Management

Early diagnosis (mainly by ultra sound)
Adequate nutrition:-
1- Caloric consumption increased by 300 Kcal per day.
2- Iron 60-100 mg per day.
3- Folic acid 1mg per day.
Frequent prenatal visit:-
observe maternal and fetal complications
1- Frequent ultra sound fetal growth, congenital anomalies, amniotic fluid.
2- Doppler.
3- BPP(Biophysical profile).

Management of twin pregnancy

The patient is seen more often than usual from mid-pregnancy onwards .

She should be seen every two weeks until 20 weeks & every weeks till 36 weeks

Investigations

1-confirming a diagnosis

2-determining chorionicity

3-detecting fetal anomalies

4-evaluating fetal growth

5-confirming fetal wellbeing

6-assisting in delivery

Antepartum management

1-Preterm labour (40%) in twin pregnancies &(75%) in triplet pregnancies

*there is no evidence that prophylactic cervical cerclage or prophylactic tocolytic agent have been beneficial.

*bed rest at home or in the hospital has not proved effective in preventing preterm labour or delivery

2- pre-eclampsia

the risk of gestational hypertension or pre-eclampsia has been reported to range from 10-20% in a twin pregnancy, 25-60% in triplet pregnancy.

3- other maternal complications

Daily supplementation of at least 60 mg of elemental iron &1mg of folic acid is recommended because of the increased risk of iron &folate deficiency anaemia

multiple pregnancy is a particular risk for the occurrence of acute fatty liver of pregnancy

Intrapartum management

1- all twin and multiple fetuses should be delivered by 40 weeks

2-the use of prostaglandins for induction & oxytocin for induction or augmentation of labour is an acceptable alternative to the elective delivery by CS

2- requires adequate obstetric & nursing staff

3-US to confirm fetal presentation & size before a decision is made on mode of delivery

Four principal combinations of presentationsCephalic/cephalic 60%Cephalic/breech 20%Breech/cephalic 10%Breech/breech 10%

The presentation of the fetuses may be

1- vertex- vertex twins

2- vertex nonvertex twins

3-higher order multiple gestation

Vertex- vertex twins

In the absence of obstetrical indications for CS delivery ,vaginal delivery should be planned regardless of gestational age.

Delay of over half an hour in the delivery of the second twin increases the ocurrence of fetal morbidity, thus the CS rate for the second twin increases with the increase in the delivery time

Vertex nonvertex presentaton

Vertex breech or vertex-transerse presentation occurs in 35-40% of all twin pregnancies selection of delivery depends on the following

*the size of the second twin

*presence of growth discordance

The availability of an obstetrician skilled in assisted breech delivery , internal podalic version & total breech extractionIf the second twin in a transverse lie or a footling presentation, the membrane should be left intact until the feet can be secured in the pelvis, following which immediate rupture of the membranes & total breech extraction should be performed

Nonvertex first twinsBreech-vertex or breech-breech occurs in 15-20% of all twin pregnancies. These cases are almost always managed by CSHigher order multiple gestation

Cesarean delivery is recomended

C.S. for Multiple Pregnancy:

Indications of C.S. :

More than 2 viable fetuses, if:weight < 2 kg, discordant growth ( i.e.; IUGR or twin-twin transfusion, or disproportionate twins, twin B larger than A (BPD > 2 mm),twin A: is non-vertex.Conjoined TwinsSingle amniotic cavity (as diagnosed by U/S or amniogram).Previous Uterine scar.During Labor: if delayed progress, fetal distress, or if twin B transverse and cervix is thickened (retained second twin).Associated pregnancy complication i.e.; severe PIH, placenta previa.Contracted PelvisLack of expertise

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Requirements for twin delivery

Large delivery room

Operating theatre and staff ready

Anaesthetist present

Senior obstetrician present

At least two midwives present

Twin resuscitaires

Ventous/forceps to hand

Blood grouped and saved

Intravenous access

Neonatologists present

Pre-mixed oxytocin infusion ready

Conjoined twins Chang and Eng Bunker (1811-1874), Chinese brothers born in Siam, now Thailand. They traveled with Barnum's circus and were billed as the Siamese Twins. They had fused livers