Interpretation
Concurring with the previous report,5 severe CP caused by umbilical cord troubles, especially cord prolapse, was characterized by a sudden onset (R-PD) in the intrapartum. It is not surprising, given these configurations of the umbilical cord lead to vulnerability to compression or torsion during uterine contractions.12,13 In contrast, we identified a high incidence of CP associated with cord morphological abnormalities developed in an antenatal period, mostly P-NR accounted for 36%. The hyper-coiled cord is reported to be more prone to torsion rather than compression or stretching.14,15 Furthermore, several histological studies showed the association between umbilical cord abnormalities and placental circulatory stasis or thrombosis.2,16,17 Such a cumulative effect on fetoplacental blood flow may result in antenatal etiology of brain injury.
We identified that most FHR deteriorations occurred during the first stage of labor and a high incidence of Hon’s pattern in the case with umbilical cord structural lesions such as velamentous insertion and multiple entanglements. Several retrospective studies showed the association of variable decelerations during the first stage of labor with umbilical cord abnormalities such as velamentous cord insertion and hyper-coiled cord.18,19 Moreover, a prospective study showed that morphological abnormalities developed in the earlier gestation were likely to coexist with placental abnormalities that affect the fetoplacental perfusion during labor.20Such cumulative distress described above might also arise during repetitive uterine contractions and could develop Hon’s pattern. As this pattern evolves over several hours, we may be able to intervene and correct the FHR pattern before severe hypoxia occurs. Therefore, morphological abnormalities of the umbilical cord have the potential of predicting such FHR alterations, and ultrasound screening for them antenatally is crucial to predispose labor and delivery care providers to greater focus on Hon’s FHR progression.
On the other hand, the prevention of CP in cases with R-PD might be difficult. A previous nationwide study on the prognosis of infants with umbilical cord prolapse found that the interval from the diagnosis of prolapse to delivery was significantly longer in infants with a poor outcome than those with intact survival (median, 30 vs. 24 minutes).21 We would not reduce such CP cases unless obstetric facilities throughout the country can provide immediate cesarean delivery within 15 minutes. However, half of the deliveries are managed in a private clinic where the emergency cesarean section is not available.
Although electronic fetal monitoring (EFM) has not yet been shown to be a good predictor of fetal asphyxia,22,23 previous studies suggested that optimal intrapartum care could offer a preventive opportunity of labor asphyxia in cases with normal admission FHR tracings.24,25 Furthermore, a retrospective study suggested the combination of EFM with clinical risk factors performed better for screening CP than EFM alone.26 As a risk screening of umbilical cord troubles before labor management, ultrasound screening, triage of pregnant women according to risks of emergency cesarean section, and appropriate intrapartum management of FHR combined with evolution patterns are recommended.5,27,28 In case these factors are recognized, the parturients should be placed under continuous observation of FHR with preparing an emergency cesarean section for early intervention to abnormal FHR that may cause fetal brain damage.