Insert Program or Hospital LogoIntroduction Life vs Limb
Fetal Limb Ischemia in Twin-Twin Transfusion SyndromeB. Ryder Connolly MS3, Andrew Gonzalez MS3, Alice Gong M.D.
UT Health San AntonioDiscussion
Case PresentationHospital CourseConclusionsReferencesHansen K, Sung CJ, Huang C, Pinar H, Singer DB, Oyer CE. Reference values for second trimester fetal and neonatal organ weights and measurements. Pediatr Dev Pathol. 2003;6:160–7.
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S. Schrey, A. Huber, K. Hecher et al., “Vascular limb occlusion in twin-twin transfusion syndrome (TTTS): case series and literature review,” American Journal of Obstetrics and Gynecology, vol. 207, no. 2, article 131, pp. e1–e10, 2012.
Texas Pediatric Society Electronic Poster ContestTwin-Twin Transfusion Syndrome (TTTS) is estimated to occur in 1:40 to 1:60 monochorionic diamniotic pregnancies. It occurs when a disproportionate amount of blood is shunted from one twin to the other, resulting in oligohydramnios in the amniotic sac of the donor twin and polyhydramnios in the amniotic sac of the recipient twin.
The treatment for severe cases of this condition consists of either serial reduction of amniotic fluid or the selective ablation of blood vessels connecting the twins with a laser. Following laser ablation, 2-13% of TTTS pregnancies will progress to Twin Anemia Polycythemia Sequence (TAPS), wherein one twin becomes anemic while the other develops polycythemia. An inter-twin hemoglobin difference of ≥8.0 g/dL in conjunction with an inter-twin reticulocyte ratio of >1.7 is required for diagnosis.
Here, we present a case of TTTS which progressed to TAPS following two laser ablations, ultimately resulting in the rare occurrence of limb ischemia in the recipient twin.Without treatment, the fetal mortality rate in TTTS is 90%, with over 50% of the survivors having significant morbidity. Following fetoscopic laser ablation, the odds of having at least one survivor increase to 82%.
TTTS may progress to TAPS following laser ablation if some of the aberrant blood vessels between donor and recipient twin remain, allowing blood to continue to pass from one twin to the other, albeit at a slower rate. The slower rate allows more time for the twins’ bodies to adjust to the disproportionate amount of blood volume but not the amount of red blood cells, thus, resulting in TAPS (distinguished from TTTS by lack of oligohydramnios and polyhydramnios).
Polycythemia-hyperviscosity syndrome occurs in the recipient twin as a complication of TAPS when hematocrit measurements reach higher than 65%. The viscous blood compromises oxygen delivery to the body and has the potential to affect many organs including brain, heart, lung, kidneys and intestines. Very rarely, the viscosity can result in limb ischemia, as was evident in this case. Since limb ischemia has been reported in cases of TTTS without polycythemia, other mechanisms are likely to be involved as well. The differential diagnosis includes umbilical arterial-steal syndrome, vascular injury, and ischemia secondary to vasoconstrictive hormones, which have been shown to be elevated in the recipient twin circulation in cases of TTTS.
A 33 year old G5P2 Hispanic female had a monochorionic, diamniotic twin pregnancy diagnosed with TTTS by Maternal Fetal Medicine specialist (MFM). Because of the severity of the TTTS (stage IV by Quintero), she was referred to Texas Children’s Hospital, Houston, TX, where she underwent two fetoscopic laser ablations. The first occurred at 19 4/7 weeks gestation and the second at 20 1/7 weeks. The procedures were performed without complications.
At 27 2/7 weeks, she presented to Laredo Medical Center with preterm labor and rupture of membranes. The twins were subsequently delivered by emergency caesarean section. Upon delivery, both babies were floppy and exhibited poor respiratory effort.
At birth, twin A (donor twin) weighed 930 grams. Apgar scores were 3 and 7 at 1 and 5 minutes respectively. She was pale and pink, and was found to be anemic (hematocrit of 17).
At birth, twin B (recipient twin) weighed 1210 grams. Apgar scores were 3 and 7 at 1 and 5 minutes of life respectively. She was ruddy and jaundiced with generalized bruising. She had severe club foot deformity of the left lower extremity and the foot was violaceous to black below the level of the left knee and medial thigh. No bands of amnion were adherent to twin B upon delivery, making amniotic band syndrome unlikely. The foot length of the necrotic left lower extremity was found to be 4.35 cm, compatible with a gestational age of around 25 weeks. This strongly suggests that the necrosis started at a gestational age after the time of fetoscopic laser ablation. She was found to be polycythemic (hematocrit of 75).
Both infants were transferred to the NICU for respiratory distress, prematurity, very low birth weight and management of clinical sepsis.In this case report, we discussed the mechanism by which TTTS can progress to TAPS following laser ablation. We also discussed how TAPS may be involved in the pathogenesis of fetal limb ischemia in cases of TTTS. Neonatologists and pediatricians should be aware of the association between TTTS and fetal limb ischemia and the possible complications of laser ablation treatment. The twins were at elevated risk for sepsis, RDS, neurodevelopmental delay, and intraventricular hemorrhage following birth. Twin B was transferred to University Hospital NICU in San Antonio for further management of left lower limb ischemia, followed shortly thereafter by Twin A for respiratory failure.
Upon arrival in San Antonio, Twin A was hypotensive and had pulmonary findings suggestive of multilobar pneumonia. She required HFOV ventilation as well as iNO for pulmonary hypertension. She also needed multiple blood transfusions. Her course was complicated by a large PDA with left atria enlargement that was unresponsive to medical management, thus requiring surgical ligation.
After evaluation of Twin B’s necrotic limb, orthopedic surgery determined that the limb would autoamputate and surgical intervention would not be required. The infant was observed closely under sepsis watch with careful wound care. Clotting profile did not show any abnormalities; hence, thrombosis by inherent hematologic disorder was ruled out. Figure 2:
X-Ray shows osseous deformity of left leg with ventral displacement of distal tibia-fibula, dislocation of tibiotalar joint, medially angulated left foot and adductus configuration of forefootFigure 1: Necrotic left lower extremity on day 1 of lifeFigure 3: Necrotic left lower extremity on day 5 of life, following autoamputation of foot