4 cases of preterm delivery complicated by recurrent vaginal bleeding; suspected of CAOS (chronic abruption-oligohydramnios sequence)

Abstract

In 1998, Elliott et al described CAOS (Chronic Abruption-Oligohydramnios Sequence) as a condition in which vaginal bleeding occurs without any identifiable cause while amniotic fluid level appears to be normal. This report highlights the need for safer and more reliable options to predict/treat this prenatal condition so as to improve the outcome for newborns. Our own experiences in treating such cases have lead to this conclusion. During the last 2 years 4 cases of CAOS were treated at the Japan Baptist Hospital. All 4 cases had episodes of recurrent bleeding occurring in the first trimester of pregnancy, and developed oligohydramnios . Of these four cases two cases resulted in IUFD and neonatal death. The infants survived in the remaining two cases. The first case developed oligohydramnios from 21 weeks of gestation and IUFD was seen in one month. The second case had preterm PROM at 22 weeks of gestation, and developed intrauterine infection within one week. The patient later delivered vaginally at 23 weeks of gestation but the infant died 2 hours after birth. The remaining 2 cases, the infection progressed and underwent cesarean section at 25 weeks of gestation. The both infants later developed CLD (chronic lung disease), but at six months old, they shows no signs of developmental abnormality. The four cases above suggest that 1) recurrent genital bleeding that occurs from the early stage of pregnancy is an important factor that can influence perinatal prognosis 2) prognosis is usually worsened if accompanied by oligohydramnios. Our observations are in keeping with Elliott et al. who reported that infants delivered preterm due to CAOS can have a worse perinatal prognosis in comparison with other preterm infants born at similar gestational stages. Having a reliable bio-marker useful for making obstetrical decision in these high risk cases may result in better prognosis for newborns. At present, the histopathology of CAOS is not clear, therefore any discussion of potential treatment options is usually limited. Generally however, for patients at an early gestational stage, the tendency is to try to prolong pregnancy for as long as possible. To ameliorate the perinatal result, patients at high risk of delivering VLBW (very low birth weight) infants should be referred to an obstetrical center with a highly developed NICU from the onset of this syndrome. Here, patients should be closely observed for maternal and fetal infection, and fetal well-being should be monitored to decide the best timing for pregnancy termination.[Adv Obstet Gynecol, 62 (4) : 327-332, 2010 (H22.11)]