1. Topic: Multiple Gestation
Presenter:
Lamin F Jarju
5th year Medical student
13th April 2010

2. Overview In 1-2% of pregnancies there is more than one fetus.
The chances of miscarriage, fetal abnormalities, poor fetal growth, preterm delivery, and intrauterine or neonatal death are considerably higher in twin than in singleton pregnancies.
In about 2-3rds of twins the fetuses are non-identical, or dizygotic and in 1-3rd they are identical, or monozygotic.
Monochorionic, compared to dichorionic, twins have a much higher risk of abnormalities and death
Maternal risks are increased in multiple pregnancies

3. overview
Monozygotic twins ("identical twins") result from the division of a single fertilized ovum.
Monozygotic twinning occurs in approximately 2.3–4 of 1000 pregnancies in all races.
The rate is remarkably constant and is not influenced by heredity, mother's age, or other factors.
Dizygotic twins ("fraternal twins") are produced from separately fertilized ova.
Slightly more than 30% of twins are monozygotic; nearly 70% are dizygotic.
Although monozygosity is random (ie, it does not fit any discernible genetic pattern), dizygosity has hereditary determinants.

4. Incidence (by Clinical Obstetrics and Gynaecology, Drife/Magowan, 2004)
54/1000 in Nigeria
4/1000 in Japan
12/1000 in UK
Identical twins: 3/1000
Preterm delivery: 40%
The incidence is higher after ovulation induction

5. definition
In general terms, multiple pregnancies consist of two or more fetuses
Twins make up the vast majority (97-98%) of multiple gestations
Pregnancies with three or more fetuses are referred to as ‘higher multiples’

6. classification The classification of multiple pregnancy is bases on :
Number of fetuses: twins, triplets, quadruplets, etc.
Number of fertilized eggs: zygosity
Number of placentas: chorionicity
Number of amniotic cavities: amniocity

7. Types of multiple gestation
Results from the ovulation and subsequent fertilization of more than one oocyte: Dizygotic (the fetuses are genetically different)
Result from the splitting of one embryonic mass to form two or more genetically identically fetuses (Monozygotic).

8. Zygosity and Chorionicity
Zygosity refers to whether the twins have come from the same ovum or from different ova, in other words whether they are identical or non-identical.
Chorionicity refers to the number of placentae.

9. Types of multiple gestation
Dizygotic twins: Diamniotic and Dichorionic.
Monozygotic Twins:
- Monochorionic, Monoamniotic
- Monochorionic , Diamniotic
- Dichorionic, Diamniotic.
Note:
Not all dichorionic pregnancies are dizygotic
All monochorionic pregnancies are monozygotic

11. Monozygotic twins
The type of monozygotic twin depends on how long after conception the split occurs:
Single embryonic mass splits into two within three days of fertilization: Diamniotic and Dichorionic.
When embryonic splitting occurs after the 3rd day following fertilization: Monochorionic and Diamniotic
Embryonic splitting after the 9th day following fertilization: Monoamniotic and Monochorionic.
Splitting after 12th day: Conjoined Twins.

12. Conjoined twins Conjoined twins are described by site of union:
PYGOPAGUS (at the sacrum),
THORACOPAGUS (at the chest),
CRANIOPAGUS (at the heads), and
OMPHALOPAGUS (at the abdominal wall).
Curiously, conjoined twins usually are female.
Numerous conjoined twins have survived separation.

14. Risk factors for multiple gestation
Maternal family history (dizygotic; monozygotic is rare).
Increasing maternal age (dizygotic).
High parity
Ovulation induction
In vitro fertilization and embryo transfer
Black race

15. Factors affecting dizygotic twins
Race ( common in blacks)
Tends to be recurrent
Aging (advanced maternal age)
Women of increased height and weight
Group O and A are more prevalent in white mothers of twins than in the general population, for unknown reasons
Excessive production of pituitary gonadotrophin
Undernutrition appears to be a negative factor
Relatively high frequency of coitus
Common after cessation of long-term contraception

16. Clinical features Increased uterine size (>4cm) for dates
Hyperemesis gravidarum
Excessive maternal weight gain that is not explained by edema or obesity
Polyhydramnios is almost 10 times more common in multiple pregnancy
Early oedema
At physical exam two poles and two different fetal heart

17. Diagnosis
History (Assisted conception, family history, increased symptoms of pregnancy, abdomen larger than expected for gestation)
Clinical examination
USG

18. Complications of twin pregnancy
Singleton (%)
Twins dichorionic (%)
Monochorionic (%)
Miscarriage at 12-23wks 1 2 12
Delivery at wks 5 10
Growth restriction 20
Fetal defects 8

19. Complications of twin pregnancy
Miscarriage
Preterm labour
IUGR
Fetal abnormalities and chromosomal defects
IUFD of one fetus
Twin to Twin transfusion syndrome
APH
Polyhydramnios
Preeclampsia
Anemia
Gestational diabetes

20. Complication unique to monochorionic twining
In all monochorionic twin pregnancies there are placental vascular anastomoses present which allow communication between the two feto-placental circulations
Imbalance in the flow of blood across these arteriovenous communications results in twin-to-twin transfusion syndrome (TTTS)

21. Complication unique to monochorionic twining
The donor fetus suffers from
Hypovolaemia (due to blood loss )
Hypoxia ( due to placental insufficiency)
Maybe growth restricted
Maybe dehydrated
Oliguric
oligohydramnios

22. Complication unique to monochorionic twining
The recipient fetus
Becomes hypervolaemic
Leading to polyuria
Polyhydramnios
Risk of myocardial damage and high cardiac output
plethoric, edematous, and hypertensive
Ascites and kernicterus are likely.

23. Differential diagnosis
Singleton pregnancy: inaccurate dates or the fetus larger than expected
Polyhydramnios: either single or multiple may be associated with excessive accumulation of fluid
Hydatidiform mole: although usu easily distinguished from multiple gestation, this complication must be considered in diagnosis early in pregnancy
Abdominal tumors complicating pregnancy: fibroid tumors of the uterus; ovarian tumors are generally single, discrete, and harder to diagnose
A distended bladder or full rectum may elevate the pregnant uterus

24. Management of pregnancy
Early booking
Proper antenatal care
Health education
USG
Prevention of anemia
Assessment of fetal wellbeing
Prevention of preterm delivery
Prevention and early diagnosis of complications

25. Management of Twin delivery
Routine growth scans on twins recommended every 4 wks in the 3rd trimester or more frequently if growth restriction is detected
Antenatal care:
Iron and calcium supplementation, vit and folic acid administration ( in an attempt to prevent anemia)
A high protein diet and more weight gain than usual
Supplementation with magnessium, zinc, as well as essential fatty acids also have been recommended
Routine hospitalization for bed rest
Prophylactic cerclage improves outcome
Early and prompt therapy for any complications (eg vaginal infections, pre-eclampsa—eclampsia)

26. Management of Twin delivery
IV line
To identify the presentation
< 34 weeks: Caesarean section
CTG if is possible
Work in team
Oxytocin infusion could be necessary after delivery of the first twin.
No ARM until advanced cervical dilatation.

27. Management of Twin delivery
External version of the second twin is if necessary, if it fail: breech extraction
No more than 30 mins between delivery of the first baby and the second.
First twin in breech and second in cephalic presentation have risk of locked twins
Be ready for possible post partum hemorrhage

28. bibliography
Obstetrics by Ten Teachers…. Eighteenth edition… edited by Philip N. Baker
(Lange)_Current Diagnosis & Treatment Obstetrics & Gynecology, Tenth Ed(2007)

29. Thanks for you kind attention!!! God bless you!!!
The end!!!
Thanks for you kind attention!!!
God bless you!!!