Multiple Pregnancy Scan & Evaluation

Multiple pregnancy is a condition in which more than one fetus develops simultaneously in the mother’s womb. In India the prevalence rates are 8 twin pregnancies per 1,000 births. Increasing rates of multiple pregnancy are seen now a days due to boom in artificial reproduction techniques. Ultrasound Diagnosis of Chorionicity and amnionicity should be done best before 16 weeks gestation. Twin peak sign or lambda sign indicates dichorionic twin gestation. T sign indicates monochorionic twin gestation.

In twin pregnancies we can offer combined screening (maternal age, NT, 1st trimester biochemical markers). SECOND TRIMESTER SCREENING CANNOT BE OFFERED. In triplet/ higher order pregnancies only Ultrasound screening is done, NO BIOCHEMICAL SCREENING SHOULD BE DONE. NIPT is useful as a TRIAGE method in high-risk cases.

In Monochorionic twins there is sharing of placenta which is associated with complications like growth discordance, placental anastomoses (TTTS, TRAP, TAPS) In Twin to Twin Transfusion syndrome (TTTS) complications increase as the stage progresses. Ultrasound should be done every 2 weeks from 16 weeks onwards. Fetal therapy in the form of Radiofrequency ablation or laser photocoagulation is done in complicated stages.

In Twin Reverse Arterial Perfusion there is an incompletely developed Acardiac twin. The primary vascular abnormality (Artery– Artery & Vein–Vein Anastomoses) cause reverse arterial perfusion sequence that allows the acardiac twin to grow as a parasite of the pump twin. The pump twin ends up in high output cardiac failure. Fetal Therapy in the form of Cord occlusion is done in such cases.