Twin to twin transfusion syndrome (TTTS)

Dr Maher Maaita MRCOG
King Hussien Medical Centre

 Brief History:

• A 30 year-old women, parity 3, all by caesarean sections, referred to King Hussein Medical Centre at 29 weeks gestation with severe polyhydraminos.
• Ultrasound examination revealed Twin pregnancy. First twin in cephalic presentation with polyhydraminos, amniotic fluid index ( AFI ) of  30, Large bladder, growth measurements > 50 centile with normal Doppler studies.
• Second twin stuck to the uterine wall with anhydraminos, absent bladder, growth measurements below 5th centile with absent end diastolic flow in the umbilical artery on Doppler studies.

Diagnosis

• The diagnosis of twin to twin transfusion syndrome (TTTS) grade 3 was made.

Management

•  The patient was counselled regarding the potential poor prognosis.
•  She was admitted to hospital and given Dexamethazone.
•  The patient underwent 3 amnioreductions, draining 3,2,2 litres over a period of 10 days.
• At 30+ weeks, the patient ruptured her membranes and underwent an emergency caesarean section. The first baby weighed 1.5 kg and was born freshly dead.
• The second twin weighed 750 mg was born alive and was admitted to the neonatal unit and was put on the ventilator.
•  Both babies were girls as shown in Fig 1. The patient made a good recovery and discharged home on day 3.

    Figure 1: TTTS

       Figure 2 : ( TTTS Babies in NICU)

      Figure 3: Face profile showing scalp oedema

       Figure 4: Recipient twin with oligohydramnios

Discussion

• It is important to scan all twins early and determine chorionicity before 14 weeks and identify this high risk group, for which increased monitoring may improve outcome.
• It is essential for genetic counselling, management for discordant anomalies and TTTS, fetal compromise and and intrauterine fetal death.
• It is a matter of counting the layers that separate the twins. If there are tow thin layers (two amniotic sacs) and two thick separate chorionic plates or one fused chorion (beyond 9 weeks) that forms the lambda at insertion of the placenta, then they are dichorionic diamniotic twins.
• However, if there are two thin layers (two amniotic sacs) inserting as a T on the placental disc, then they are monochorionic diamniotic twins.
• Our patient was unbooked at our hospital and presented late with stage (III) TTTS.
• She and her husband were aware of the poor prognosis and the high mortality.
•  We performed amnioreduction. Available data suggests that amnioreduction is only effective in mild cases of TTTS ( Stages I-II).
• Where as amnioreduction is a palliative and repetitive measure, fetoscopic laser coagulation of the vascular anastomoses seeks to address the underlying cause of the disease through a single intervention.
•  A recent controlled study showed that laser is superior to amnioreduction in the treatment of TTTS.
• Unfortunately we do not have the facility to do laser coagulation at our centre.
• Monochorionic twins are high risk pregnancies and should be referred to a tertiary centre and followed closely by a fetal medicine specialist every 2 weeks from 16 weeks onward to look for complications and mainly to look for TTTS.      

Twin to twin Transfusion Syndrome (Key Points)

• Twin to twin transfusion (TTTS) is a complication unique to monochorionic multiple pregnancies.
•  In most monochorionic twin gestations, interfetal transfusion across the anastomoses is a constant but balanced phenomenon.
•  However in 10% to 15% of monochorionic twins, a chronic imbalance in net flow develops, resulting in TTTS.
•  Hypovolemia, oliguria and oligohydraminos develop in the donor twin producing the “ stuck twin “ phenomenon.
• Hypervolemia, polyuria, and hydraminos evolve in the recipient twin, who can develop circulatory overload and hydrops.
• TTTS usually occurs between 15 and 26 weeks.
• There is a staging system based on the sonographic time sequence of cases with progressive deterioration.
• Stage I cases include those with hydraminos in the recipient sac but the bladder of the donor twin still visible.
•  In stage II, the bladder of the donor twin remains empty (stuck twin).
• Stage III is characterized by severely abnormal Doppler studies.
• Fetal hydrops means stage IV and the end stage V corresponds to fetal death of one or both twins.
• In view of the poor survival rates with conservative management, there is little disagreement that therapy should be offered.
• The four most commonly used therapies for midtrimester TTTS are amnioreduction, fetoscopic laser coagulation of the vascular anastomoses, septostomy, and selective fetocide by cord occlusion.