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Table of Content Volume 16 Issue 3 - December 2020
Ultrasound detection of nuchal cord and its effects on labour and neonatal outcome
Ravi Kumar1*, Dileep K2
1Senior Resident, 2Assistant Professor, Department of Radiology, Apollo Medical College and Research Institute, Chittoor, INDIA. Email: raviradio2k11@gmail.com
Abstract Background: A nuchal cord occurs when the umbilical cord becomes wrapped around the foetal neck 360°. The diagnosis of a nuchal cord is made, when there is a suspicion due to the presence of variable decelerations in the fetal heart rate on the cardiotocograph (CTG) during labour. The present study is undertaken to know the prenatal diagnosis of nuchal cord and its effects on the labour and neonate. Materials and Methods: It is a prospective comparative study done in a district hospital attached to the Apollo institute of medical sciences and research, Chittoor between March 2019 to February 2020. A total of 200 women after 36 weeks of gestation were included and studied variation in the type of delivery and neonatal factors by calculating relative risk. Results: Nuchal cord was present in 37 (18.5%) babies after delivery. The sensitivity of ultrasound detection of nuchal cord prior to delivery is 37.8% and the specificity is 79.8%. The risk of caesarean section is high in women who had given birth to babies with nuchal cord, but difference is not significant. Nuchal cord at birth has no effect on APGAR scores of the babies at 1 minute or 5 minutes, abnormal cardiotocography, admission into neonatal intensive care unit and arterial cord pH less than 7.2. Conclusions: Prenatal diagnosis of nuchal cord through ultrasound after 36 weeks of gestation is of limited use as the sensitivity is low. The presence of nuchal cord at birth does not appear to increase the risk of caesarean section or of poor neonatal outcome. Key Words: Nuchal cord, Ultrasound, labour, neonatal outcome
INTRODUCTION A nuchal cord occurs when the umbilical cord becomes wrapped around the foetal neck 360°.1 It is a common finding at delivery. The prevalence at delivery has been reported as being between 6% and 37% and the incidence may increase steeply after 38 weeks.2,3 Around 25–50% of nuchal cords formed at any one time will resolve prior to delivery.4 About 20%–60% of all foetal deaths are attributed to foetal asphyxia.5 However, aetiology in all cases of foetal asphyxia is not clearly established. Asphyxia is most commonly seen as a result of reduced placental circulation, but rarely, it might be secondary to umbilical cord complications. Nuchal cord accident comprises 5%–18% of all foetal asphyxia cases, and 10% of stillbirth were due to umbilical cord complications.6 The diagnosis of a nuchal cord is made, when there is a suspicion due to the presence of variable decelerations in the fetal heart rate on the cardiotocograph (CTG) during labour, particularly if there is ‘shouldering’ or if they are of a ‘double variable’ or ‘W pattern’.7 Other indirect methods of diagnosis have been described by demonstrating fetal heart rate changes following application of manual compression of the fetal neck abdominally or in response to acoustic vibratory stimulation.8,9 Ultrasound diagnosis of a nuchal cord was first described in 1982 by Jouppila and Kirkinen10 and since then there have been a very few case reports in which ultrasound diagnosis has aided obstetric management. So, the present study is undertaken to know the prenatal diagnosis of nuchal cord and its effects on the labour and neonate.
MATERIALS AND METHODS It is a prospective comparative study done in a district hospital attached to the Apollo institute of medical sciences and research, Chittoor between March 2019 to February 2020. A total of 200 women after 36 weeks of gestation were included in to the study among which 47 were having nuchal cord around the neck at least three of the four sides of the neck and remaining 153 were not having nuchal cord in transabdominal ultrasound scan by using an Aloka 1700 ultrasound machine (Aloka Co. Ltd, Mitaka-shi, Tokyo, Japan) with a 3.5-MHz abdominal probe. All the ultrasound scans were performed by the single radiologist and the information wasn’t revealed to women or clinician. After delivery of the baby, patients were grouped into Patients delivered a baby with nuchal cord and without nuchal cord and studied variation in the type of delivery and neonatal factors. Informed consent was obtained from the women for including into the study and Institutional ethical committee permission was obtained before starting of the study. Information was collected in predesigned questionnaire and entered into Microsoft excel. Data was analysed using SPSS statistics 21.0 version. Results were expressed in proportions and percentages and relative risk was calculated to assess the risk.
RESULTS Nuchal cord was present in 37 (18.5%) babies after delivery. Among which 30 (15%) babies have single loop, 6 (3%) babies have double loop and 1 (0.5%) baby have three loops of cord noticed around the neck after delivery. In table 1 it was shown that the sensitivity of ultrasound detection of nuchal cord prior to delivery is 37.8% and the specificity is 79.8%. In table 2 it was shown that, among 37 babies born with nuchal cord, 15 (40.5%) babies delivered by caesarean section, 2 (5.4%) delivered by forceps delivery due to foetal distress and 20 (54.1%) delivered by normal vaginal delivery without any assistance and among 163 babies born without nuchal cord, 59 (36.2%) babies delivered by caesarean section, 10 (6.1%) delivered by forceps delivery due to foetal distress and 94 (57.7%) delivered by normal vaginal delivery without any assistance. Though the risk of caesarean section is high in women who had given birth to babies with nuchal cord, difference is not significant. In table 3 it was shown that, 6 (16.2%) babies born with nuchal cord and 21 (12.9%) babies without nuchal cord has APGAR score less than 7 at 1 minute and 1 (2.7%%) baby born with nuchal cord and 3 (1.8%) babies without nuchal cord has APGAR score less than 7 at 5 minutes after birth. Abnormal cardiotocography was seen in 12 (32.4%) babies with nuchal cord and 49 (30.1%) babies without nuchal cord. Around 5 (13.5%) babies with nuchal cord and 16 (9.8%) babies without nuchal cord has been admitted into neonatal intensive care unit. Around 6 (16.2%) babies with nuchal cord and 29 (17.8%) babies without nuchal cord has arterial cord pH less than 7.2. Nuchal cord at birth has no effect on APGAR scores of the babies at 1 minute or 5 minutes, abnormal cardiotocography, admission into neonatal intensive care unit and arterial cord pH less than 7.2. None of the neonates born with nuchal cord has been died in the follow-up period of 1 year.
Table 1: The effectiveness of ultrasound in detecting the nuchal cord prior to the labour
Table 2: Association of nuchal cord at delivery and mode of delivery
Table 3: Association of nuchal cord at delivery and neonatal outcome
DISCUSSION The present study was undertaken to know the effectiveness of using trans-abdominal ultrasound in detecting nuchal cord prior to the delivery after 36 weeks of gestation and found the sensitivity of 37.8% and the specificity is 79.8%, similar to the findings of Peregrine et al.11 study. These two studies have lower sensitivity compared to other studies because the ultrasound scan was done after 36 weeks of pregnancy at which fetal crowding, low position of the fetal head or reduced amniotic fluid volume is common to create problem to visualize nuchal cord.12 Present study reported that there is no significant risk of having emergency caesarean section in babies born with nuchal cord at delivery. But in Jauniaux et al.13 and Rhoades et al.14 studies, it was shown that the risk of having caesarean section is more in babies born with nuchal cord. The difference was missed in the present study may be due to less sample size. Present study also reported presence of nuchal cord at birth has no effect on APGAR scores of the babies at 1 minute or 5 minutes, abnormal cardiotocography, admission into neonatal intensive care unit and arterial cord pH less than 7.2. Similarly, studies done by Jauniaux et al.13 and Carey el al15 also reported no increase in the risk of stillbirth, especially if risk factors such as hypertension, abruption, diabetes, premature rupture of the membranes, oligohydramnios and major fetal anomalies are controlled. Irrespective of this some retrospective studies have been reported poor neonatal outcome and an increase in perinatal mortality.16,17 Collins JH has suggested that the nuchal cords which are ‘locked’, where the placental end passes under the umbilical end rather than ‘unlocked’ are more often associated with a poor outcome,18 but this has not been demonstrated on ultrasound. It may be that the presence of other associated features such as reduced fetal movements or other markers of concern about fetal well-being will identify fetuses at risk.
CONCLUSIONS Prenatal diagnosis of nuchal cord through ultrasound after 36 weeks of gestation is of limited use as the sensitivity is low. The presence of nuchal cord at birth does not appear to increase the risk of caesarean section or of poor neonatal outcome. Further, the study is recommending that further research should be directed towards improving the diagnostic techniques available for identifying nuchal cords in order to detect maximum number of cases with nuchal cord to limit the false negatives to minimum level.
REFERENCES
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Height, IVDL-Intervertebral Disc Length
Policy for Articles with Open Access
Authors who publish with MedPulse International Journal of Radiology(Print ISSN: 2579-0927) (Online ISSN: 2636 - 4689) agree to the following terms: Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal. Authors are permitted and encouraged to post links to their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work. |
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