Single fetal death in twin gestation.

Abstract

S INGLE FETAL DEATH is an unusual complication of a twin pregnancy. Occasionally, death may be attributed to placental insufficiency associated with maternal disease. However, the cause of death is usually unclear. Theoretical explanations include cord accidents, twin-to-twin transfusion syndrome, and placental abruption. It appears that the surviving twin is at risk for perinatal morbidity and mortality. The incidence of neurologic sequelae was reported to be 20%) l and a recent review of 14 published reports indicated that 46.2 % of the liveborn twins suffered major morbidity or death. 2 The prenatal death of one twin could result in the transfer of tbromboplastin to the live fetus. Thromboembolism might then produce multiple organ injury from intravascular coagulation within the shared fetal circulation, in the absence of maternal coagulopathy. It is also feasible that in cord accidents, damage to the survivor occurs at the time of the insult, which results in the demise of the co-twin. Whether neurologic injury to the survivor could precede death of the co-twin is an intriguing question. The answer becomes crucial in the discussion of whether early delivery might be of benefit to the remaining twin. Perinatal neuropathology cannot establish the nature and timing of the insult, as there is no single pathologic change in the neonatal brain that is specific for a particular etiologic factor. Preterm delivery and intrapartum complications resulting in neonatal morbidity make it difficult to assess whether a given outcome was related to an antepartum event. Currently used methods of fetal assessment, such as the non-stress-test (NST), contraction-stress test (CST), and biophysical profile score (BPS), will give no indication of brain damage unless there is brainstem involvement. The antenatal diagnosis of intraventricular hemorrhage (IVH) can be made by high-resolution ultrasound scans of the fetal head. IVH is the most common neurologic lesion resulting from perinatal asphyxia or trauma and preterm delivery. However, IVH does not seem to be a prominent pathologic feature in this clinical situation. This may reflect failure of diagnosis, as neonatal head scans of high-risk neonates are not performed routinely in many centers. The literature suggests that neurologic injury after single fetal death in twin gestation occurs largely to the cortical white matter from thromboembolism and/or ischemia. Hence, it is unlikely that ultrasound or computerized tomography (CT) scans will be useful for antenatal diagnosis of neurologic damage in the survivor. The newer technique of magnetic resonance imaging (MRI) could potentially detect this kind of neurologic lesion in the early stages and is an area for future investigation. The risk of maternal complications such as preeclampsia and disseminated intravascular coagulation (DIC) must be considered in any approach to management. Additional factors, including the psychologic impact on the mother, a theoretical risk of delayed sepsis, and the possibility of intrapartum problems (obstructed labor or fetal distress), create a complex and perplexing problem for the clinician. Maternal transfer to a tertiary care perinatal center is recommended to provide the intensive fetal surveillance, neonatal care, and pediatric follow-up which becomes necessary. Finally, in the area of prevention, new techniques to measure fetal and uterine blood flow using pulsed Doppler ultrasound may allow earlier detection of twin to twin transfusion syndrome than standard biometric evaluation.