Is nuchal cord justified as a cause of obstetrician anxiety?

Inconsistent definitions of prolonged labor in international literature: a scoping review

Objective

Prolonged labor is the commonest indication for intrapartum cesarean section, but definitions are inconsistent and some common definitions were recently found to overestimate the speed of physiological labor. The objective of this review is to establish an overview of synonyms and definitions used in the literature for prolonged labor, separated into first and second stages, and establish types of definitions used.

Data sources

A systematic search was conducted in PubMed, Embase, Web of Science, Cochrane Library, Emcare, and Academic Search Premier.

Study eligibility criteria

All articles in English that (1) attempted to define prolonged labor, (2) included a definition of prolonged labor, or (3) included any synonym for prolonged labor, were included.

Methods

Data on study design, year of publication, country or region of origin, synonyms used, definition of prolonged first and/or second stage, and origin of provided definition (if not primarily established by the study) were collected into a database.

Results

In total, 3402 abstracts and 536 full-text papers were screened, and 232 papers were included. Our search established 53 synonyms for prolonged labor. Forty-three studies defined prolonged labor and 189 studies adopted a definition of prolonged labor. Definitions for prolonged first stage of labor were categorized into: time-based (n=14), progress-based (n=12), clinician-based (n=5), or outcome-based (n=4). For the 33 studies defining prolonged second stage, the majority of definitions (n=25) were time-based, either based on total duration or duration of no descent of the presenting part.

Conclusions

Despite efforts to arrive at uniform labor curves, there is still little uniformity in definitions of prolonged labor. Consensus on which definition to use is called for, in order to safely and respectfully allow physiological labor progress, ensure timely management, and assess and compare incidence of prolonged labor between settings.

Umbilical Artery Cord Gas Abnormalities in the Presence of a Nuchal Cord in Term Singleton Pregnancies: A Cohort Study

OBJECTIVE

The clinical significance of nuchal cord (NC) at the time of delivery is unclear. Studies have found that NC is associated with lower umbilical artery (UA) pH. Since fetal hypercarbia precedes respiratory acidosis, we hypothesize UA pCO2 is elevated in neonates with NC at the time of delivery.

STUDY DESIGN

This is a secondary analysis of a prospective cohort study of women with full-term singleton pregnancies admitted in labor or for induction of labor at an institution with a universal umbilical cord gas policy. We compared patients with NC at the time of delivery to those without NC. Women were excluded if they did not have validated UA gases, had a major fetal anomaly, or had an intrauterine fetal demise. The primary outcome of the study was UA pCO2. Secondary outcomes were other components of UA gas and neonatal morbidity composite. Baseline characteristics were compared utilizing chi-square or Fisher's exact test or the Student's t-test. UA gas parameters were compared using the Kruskal-Wallis test. Multivariable logistic regression was utilized to adjust for confounders.

RESULTS

Of the 8,580 study participants, 7,608 had validated umbilical cord gases. The incidence of NC in the population was 24.15% (n = 1,837). UA pCO2 was higher in those with NC than without (58 mm Hg [53-64] vs. 55 mm Hg [50-60], p < 0.01). There was a greater odds of hypercarbia in the NC group (pCO2 > 65 mmHg; adjusted odds ratio [aOR]: 1.97, 95% confidence interval [CI]: 1.72-2.25, p < 0.01). Additionally, the NC group was more likely to be mildly acidemic (pH < 7.2, aOR: 1.74, 95% CI: 1.51-2.01, p < 0.01). There was no difference in composite neonatal morbidity between the groups.

CONCLUSION

NC is associated with an increased risk of hypercarbia and acidemia. However, this is not associated with increased risk of neonatal morbidity.

KEY POINTS

· Nuchal cord is associated with an increased risk of hypercarbia and mild acidemia.. · Nuchal cord is not likely associated with neonatal morbidity.. · Neonatal management should not be altered due to the presence of a nuchal cord at delivery..

Identifying causes and associated factors of stillbirths using autopsy of the fetus and placenta

PURPOSE

The study aimed to evaluate the causes of death and associated factors in cases of stillbirth, using post-mortem examination and applying a rigorous, evidence-based holistic approach.

METHODS

Our retrospective observational study included cases of autopsy following stillbirth that occurred at our tertiary medical center during a period of 8 years. Detailed up-to-date criteria that incorporate clinical reports, medical history, prenatal imaging, and histopathological findings were used to evaluate the cause of death and associated factors.

RESULTS

After applying our proposed methodology, 138 cases of stillbirth were classified into eight categories based on the causes of death. A definitive cause of death was observed in 100 (72%) cases, while 38 (28%) cases were considered unexplained. The leading cause of death was placental lesions (n = 39, 28%) with maternal vascular malperfusion (MVM) lesions being the most common (54%). Ascending infection was the second most common cause of fetal death (n = 24, 17%) and was often seen in the setting of preterm labor and cervical insufficiency.

CONCLUSION

The largest category of cause of death was attributed to placental pathology. Using rigorous detailed up-to-date criteria that incorporate pathological and clinical factors may help in objectively classifying the cause of death.

Adverse outcomes of nonnuchal umbilical cord entanglement

OBJECTIVE

To evaluate perinatal effects of umbilical cord entanglement (UCE) of different body parts.

METHODS

The database of a tertiary medical center was retrospectively searched for women who gave birth to a liveborn singleton newborn in 2014-2018. Those diagnosed postpartum with UCE were matched 1:10 with women who were not and compared for adverse obstetric and neonatal outcomes, overall and by site of entanglement.

RESULTS

A total of 14 299 women were evaluated, of whom 1243 were diagnosed with UCE: 78.7% neck, 26% trunk, 6.7% limb. UCE was associated with lower birth weight percentile and higher rate of small for gestational age, but findings were significant only for neck and trunk UCE. On multivariate regression analysis adjusted for maternal age, parity, gestational age at birth, and history of cesarean delivery, UCE was an independent risk factor for nonreassuring fetal heart rate, labor induction, operative vaginal delivery, cesarean delivery, and meconium-stained amniotic fluid, but not for lower absolute birth weight/birth weight percentile, small for gestational age, low 1-min Apgar score, or neonatal asphyxia.

CONCLUSION

While fetuses with UCE might be more compromised during labor, they apparently recover shortly after birth. The impact on perinatal outcomes was similar for UCE of the neck and trunk and lower for UCE of the limb.

Case Report: Spontaneous Fetal Demises at Third Trimester of Pregnancy Due to a Double Lopped Nuchal Cord in Camelus dromedarius

The umbilical cord acts as the critical lifeline of the developing fetus by providing nutrients and oxygen to it. Umbilical cord abnormalities are considered the leading cause of stillbirth in humans, but information on stillbirths associated with umbilical cord abnormalities is very scant in the clinical practice of animals. Here, we described a case of fetal demise in camels indicated to be caused by fetal death from strangulation by its umbilical cord, which is commonly known as the nuchal cord. A pregnant camel at its 36 weeks of gestation spontaneously aborted a single fetus. The camel was 5 years old and nullipara. A 6-day-old cloned embryo was transferred transcervically to the recipient. Pregnancy was confirmed 50 days after embryo transfer by ultrasonography, and the pregnant camel was maintained under a standard nutritional plan. The neck of the aborted fetus was strangulated tightly by a double loop of the umbilical cord. There was no congenital anomaly or other malformation in the fetus. We concluded that the nuchal cord was tightly coiled around the neck of the fetus and interfered with the blood flow in the fetus by collapsing the umbilical vein and subsequently causing fetal death and abortion. To the authors' knowledge, this is the first reported case of a nuchal cord in camels.

Umbilical cord characteristics and their association with adverse pregnancy outcomes: A systematic review and meta-analysis

OBJECTIVE

Current data on the role of the umbilical cord in pregnancy complications are conflicting; estimates of the proportion of stillbirths due to cord problems range from 3.4 to 26.7%. A systematic review and meta-analysis were undertaken to determine which umbilical cord abnormalities are associated with stillbirth and related adverse pregnancy outcomes.

METHODS

MEDLINE, EMBASE, CINAHL and Google Scholar were searched from 1960 to present day. Reference lists of included studies and grey literature were also searched. Cohort, cross-sectional, or case-control studies of singleton pregnancies after 20 weeks' gestation that reported the frequency of umbilical cord characteristics or cord abnormalities and their relationship to stillbirth or other adverse outcomes were included. Quality of included studies was assessed using NIH quality assessment tools. Analyses were performed in STATA.

RESULTS

This review included 145 studies. Nuchal cords were present in 22% of births (95% CI 19, 25); multiple loops of cord were present in 4% (95% CI 3, 5) and true knots of the cord in 1% (95% CI 0, 1) of births. There was no evidence for an association between stillbirth and any nuchal cord (OR 1.11, 95% CI 0.62, 1.98). Comparing multiple loops of nuchal cord to single loops or no loop gave an OR of 2.36 (95% CI 0.99, 5.62). We were not able to look at the effect of tight or loose nuchal loops. The likelihood of stillbirth was significantly higher with a true cord knot (OR 4.65, 95% CI 2.09, 10.37).

CONCLUSIONS

True umbilical cord knots are associated with increased risk of stillbirth; the incidence of stillbirth is higher with multiple nuchal loops compared to single nuchal cords. No studies reported the combined effects of multiple umbilical cord abnormalities. Our analyses suggest specific avenues for future research.

Umbilical Cord Abnormalities and Stillbirth

OBJECTIVE

Umbilical cord abnormalities are commonly cited as a cause of stillbirth, but details regarding these stillbirths are rare. Our objective was to characterize stillbirths associated with umbilical cord abnormalities using rigorous criteria and to examine associated risk factors.

METHODS

The Stillbirth Collaborative Research Network conducted a case-control study of stillbirth and live births from 2006 to 2008. We analyzed stillbirths that underwent complete fetal and placental evaluations and cause of death analysis using the INCODE (Initial Causes of Fetal Death) classification system. Umbilical cord abnormality was defined as cord entrapment (defined as nuchal, body, shoulder cord accompanied by evidence of cord occlusion on pathologic examination); knots, torsions, or strictures with thrombi, or other obstruction by pathologic examination; cord prolapse; vasa previa; and compromised fetal microcirculation, which is defined as a histopathologic finding that represents objective evidence of vascular obstruction and can be used to indirectly confirm umbilical cord abnormalities when suspected as a cause for stillbirth. We compared demographic and clinical factors between women with stillbirths associated with umbilical cord abnormalities and those associated with other causes, as well as with live births. Secondarily, we analyzed the subset of pregnancies with a low umbilical cord index.

RESULTS

Of 496 stillbirths with complete cause of death analysis by INCODE, 94 (19%, 95% CI 16-23%) were associated with umbilical cord abnormality. Forty-five (48%) had compromised fetal microcirculation, 27 (29%) had cord entrapment, 26 (27%) knots, torsions, or stricture, and five (5%) had cord prolapse. No cases of vasa previa occurred. With few exceptions, maternal characteristics were similar between umbilical cord abnormality stillbirths and non-umbilical cord abnormality stillbirths and between umbilical cord abnormality stillbirths and live births, including among a subanalysis of those with hypo-coiled umbilical cords.

CONCLUSION

Umbilical cord abnormalities are an important risk factor for stillbirth, accounting for 19% of cases, even when using rigorous criteria. Few specific maternal and clinical characteristics were associated with risk.

Current Perspectives of Prenatal Sonographic Diagnosis and Clinical Management Challenges of True Knot of the Umbilical Cord

Umbilical cord accidents preceding labor are rare. Single and multiple nuchal cords, and true knot(s) of the umbilical cord, are often incidental findings noted at delivery of non-hypoxic non-acidotic newborns without any evidence of subsequent adverse neonatal outcome. In contrast to single nuchal cords, true knots of the umbilical cord, which occur in between 0.04% and 3% of all deliveries, have been associated with a reported 4 to 10 fold increased risk of stillbirth. First reported with real-time ultrasound, current widespread application of color Doppler, power Doppler and three-dimension sonography, has enabled increasingly more accurate prenatal sonographic diagnoses of true knot(s) of the umbilical cord. Reflecting the inability to visualize the entire umbilical cord at prenatal ultrasound assessment, despite detailed second and third-trimester scanning, many occurrences of incidental true knot of the umbilical cord remain undetected and are noted only at delivery. Although prenatal sonographic diagnostic accuracy is increasing, false positive sonographic diagnosis of true knot of the umbilical cord cannot be ruled out with certainty, and must continue to be considered clinically. Notwithstanding the inability to diagnose all true knots, currently there is a clear absence of clinical management guidelines by governing bodies regarding patients in whom prenatal sonographic diagnosis of true knot(s) of the umbilical cord is / are suspected. As a result, in many prenatal ultrasound units, suspected sonographic findings suggestive of or consistent with true knot of the umbilical cord are often disregarded, not documented, and patients are not uniformly informed of this potentially life-threatening condition, which carries an associated considerable risk of stillbirth. This commentary will address current perspectives of prenatal sonographic diagnostic and management challenges associated with true knot(s) of the umbilical cord in singleton pregnancies.

Electronic Fetal Monitoring and Neonatal Outcomes when a Nuchal Cord Is Present at Delivery

OBJECTIVE

This study aimed to determine the association between nuchal cord, electronic fetal monitoring parameters, and adverse neonatal outcomes.

STUDY DESIGN

This was a prospective cohort study of 8,580 singleton pregnancies. Electronic fetal monitoring was interpreted, and patients with a nuchal cord at delivery were compared with those without. The primary outcome was a composite neonatal morbidity index. Logistic regression was used to adjust for confounders.

RESULT

Of 8,580 patients, 2,071 (24.14%) had a nuchal cord. There was no difference in the risk of neonatal composite morbidity in patients with or without a nuchal cord (8.69 vs. 8.86%; p = 0.81). Nuchal cord was associated with category II fetal heart tracing and operative vaginal delivery (OVD) (6.4 vs. 4.3%; p < 0.01).

CONCLUSION

Nuchal cord is associated with category II electronic fetal monitoring parameters, which may drive increased rates of OVD. However, there is no significant association with neonatal morbidity.

Impact of nuchal cord on antenatal and intrapartum foetal heart rate surveillance and perinatal outcome

Analysing antepartum and intrapartum computerised cardiotocographic (cCTG) parameters in physiological term pregnancies with nuchal (NC) or body cord (BC), in order to correlate them with labour events and neonatal outcome. We enrolled 808 pregnant women, composed of 264 with 'one NC', 121 with 'multiple NCs', 39 with BC and 384 with 'no NC', were monitored from the 37th week of gestation before labour, while 49 pregnant women with 'one or more NCs' and 47 with 'no NCs' were analysed during labour. No differences in maternal characteristics, foetal pH at birth and 5-min Apgar score were observed. The birth weight was significantly lower in the 'multiple NCs' group, while 1-minute Apgar score was lower in the BC group than the other groups, respectively. No relevant differences in cCTG parameters were observed, except for LTI, Delta and number of variable decelerations in antepartum period and only variable deceleration in intrapartum period.Impact statementWhat is already known on this subject? Ultrasound cannot predict which foetuses with NCs are likely to have problem during labour. The question arose if single or multiple NC could affects FHR monitoring prior and during labour.What do the results of this study add? Computerised cardiotocography (cCTG) is a standardised method developed to reduce inter- and intra-observer variability and the poor reproducibility of visual analysis. Few studies have investigated the influence of NCs on FHR variability and, to our knowledge, no one has evaluated its linear and nonlinear characteristics in antepartum and intrapartum period using a computerised analysis system. No differences in maternal characteristics, foetal pH at birth and 5-min Apgar score were observed. Birth weight was significantly lower in the 'multiple NCs' group, while 1-min Apgar score was lower in the BC group than the other groups, respectively. Foetuses with 'one or more NCs' evidenced a larger number of prolonged second stage and meconium-stained liquor cases, while the operative vaginal delivery and emergency caesarean section rates were unchanged. No relevant differences in cCTG parameters were observed, except for LTI, Delta and number of variable decelerations in antepartum period and only variable deceleration in intrapartum period.What are the implications of these findings for clinical practice and/or further research? cCTG monitoring results confirmed their usefulness for assessing the state of good oxygenation for all foetuses investigated.

Adverse pregnancy outcomes and multiple nuchal cord loops

PURPOSE

To evaluate the effects of nuchal cord and the number of loops during labor and delivery on delivery outcomes among women with singleton pregnancy who delivered vaginally.

METHODS

This retrospective cohort study included 42,798 women with singleton, vertex, and vaginal deliveries at 24-43 weeks of gestation. We analyzed delivery outcomes based on the number of nuchal cord loops.

RESULTS

A total of 42,798 deliveries met the inclusion criteria, of which, 3809 (8.9%) had nuchal cord with 1 loop at delivery, 1035 (2.42%) had 2 loops, and 258 (0.6%) had 3 loops. Nuchal cord with 3 loops compared to no nuchal cord has been associated with higher incidence of intrauterine fetal death (1.9%), Apgar scores less than 7 at 1 and 5 min (7.4%, 2.3%), and higher rate of operative vaginal deliveries (17.5%). Nuchal cord with 2 or 3 loops was associated with higher incidence of intrauterine growth restriction (10.2%, 11.6%).  In a multiple logistic regression model, nuchal cord with 3 loops was an independent risk factor for operative vaginal delivery and Apgar score less than 7 in 1 min.

CONCLUSIONS

In the case of vaginal delivery in the presence of nuchal cord, as the number of nuchal cord loops increased, so did the number of adverse delivery outcomes. While 3 loops were associated with higher incidence of intrauterine fetal death, intrauterine growth restriction, increased operative vaginal deliveries, and low Apgar scores, 1 loop was not associated with adverse perinatal outcomes.

The impact of nuchal cord on umbilical cord blood gas analysis and ischaemia-modified albumin levels in elective C-section

This study was designed to evaluate umbilical cord ischaemia-modified albumin (IMA) levels and the cord blood gas parameters of foetuses with or without nuchal cords, at the time of elective C-section. The cross-sectional study population consisted of the patients who were admitted to the Tertiary Care Center between February and June 2015. Women with uncomplicated single term gestations between 37 and 40 completed weeks and scheduled for elective C-sections were included in the study. Fifty cases with a nuchal cord and 50 cases without a nuchal cord were recruited. Nuchal cord blood gas analysis and the IMA levels were evaluated. The IMA levels in umbilical artery of foetuses both in the study and control groups were similar (0.714 ± 0.150 vs. 0.689 ± 0.107 ABSU, p = .340, respectively). The umbilical artery pH values of the study group were significantly lower than that in the control group (7.31 ± 0.04 vs. 7.32 ± 0.03, p = .042; respectively). The results of the current study indicate that the nuchal cord has an impact on the foetal cord blood gas parameters to some extent before the initiation of labour. Fortunately, this impact does not end up with foetal tissue ischaemia, as confirmed by the IMA levels. Impact statement What is already known on this subject? The impact of nuchal cord on perinatal outcomes has been the subject of research for many years. Although the accumulated data has pointed out some unfavourable perinatal effects, the heterogeneity of the study groups both including a vaginal delivery and C-section and the inability to adjust the interfering factors ended up with some controversies. This is why there is not much known about the effects of the nuchal cord in women who are not in the labour process. What do the results of this study add? The current study aimed to exclude the interfering effects such as the active stage of labour. In this study, elective caesarean sections were selected as the study population to evaluate the effects of the nuchal cord on cord blood gas parameters and the IMA values. pH analysis in cord blood is used to detect hypoxia and the IMA is a new ischaemia marker. The results revealed that the in utero nuchal cord is associated with a significantly higher pCO₂ and lower pH values and similar IMA values. What are the implications of these findings for clinical practice and/or further research? The final outcome supports that the nuchal cord causes alterations in cord blood gas analysis but this does not reach critical levels. Therefore, the results show that there is no need to change clinical practice when the nuchal cord is detected by ultrasound in a term gestation.

[Cord accident after external cephalic version: Reality or mostly myth?]

OBJECTIVES

To study the occurrence of cords accident (nuchal cords, prolapse, and braces) after external cephalic version according to its failure or success.

METHODS

Retrospective study between 1998-2015 comparing in the cord accident diagnosed at delivery (by midwife or doctors according to mode of delivery): Patients with attempt ECV: Group 1 cephalic presentation after successful ECV with trial of labor, and Group 2 failed ECV followed by elective cesarean or trial of labor. Patients with no attempt ECV Group 3 spontaneous cephalic presentation matching for delivery date, maternal age, parity, body mass index, and delivery history with group 1, Group 4 Breech presentation without attempt ECV with trial of labor.

RESULTS

A total of 776 women with breech presentation were included (198 in group 1, 446 in group 2, 396 in group 3 and 118 in group 4). The prevalence of cord accident did not differ according to ECV attempt (17.08 % versus 18.9 %), to cephalic presentation (group 1: 24.7 % versus group 3: 25 %) and to breech presentation (group 2: 16.9 % versus group 4: 17.2 %). The trial of labor after failed ECV did not increase the risk of cord accident when compared with elective cesarean (17.4 % versus 16 %). A prolapse cord was only observed after trial of labor, i.e. in groups 1, 2 and 4 without difference (respectively 1, 0.8 and 1.7 %). In each group, the rate of cesarean was not different according to the presence of nuchal cord.

CONCLUSION

Success or failed External cephalic version is not associated with an increased risk of cord accident.

The association between umbilical cord abnormalities and the development of non-reassuring fetal heart rate leading to emergent cesarean deliveries

OBJECTIVE

To study the contribution of umbilical cord (UC) abnormalities in emergent cesarean deliveries (ECDs) for non-reassuring fetal heart rate (NRFHR) and to explore their association with placental histopathology and neonatal outcome.

STUDY DESIGN

Data from 530 ECDs for NRFHR were reviewed for the occurrence of UC abnormalities. Those included the presence of UC entanglements, the number and location of loops, true knots and short cord (<50 cm). Multiple UC entanglements were defined as ⩾ 2 UC loops. Results were compared with 530 vaginal deliveries (VD group) matched for maternal age, parity and gestational age. Additionally, we compared neonatal outcome and placental histopathology in cases of ECDs with a single vs multiple UC entanglements. Neonatal outcome consisted of low Apgar score (⩽ 7 at 5 min), cord blood pH ⩽ 7.1 and composite neonatal outcome that was defined as one or more of respiratory distress, necrotizing enterocolitis, sepsis, transfusion, ventilation, seizure, hypoxic-ischemic encephalopathy, phototherapy or death. Placental lesions were classified as: lesions related to maternal vascular supply, lesions related to fetal vascular supply (consistent with fetal thrombo-occlusive disease), and maternal and fetal inflammatory responses.

RESULTS

UC entanglements, true knots and short cords were all more common in the ECD group compared with the VD group, P<0.001, P=0.002, P=0.004, respectively. The rate of one loop entanglement did not differ between the groups. The rate of multiple UC entanglements was higher in the ECD group compared with the VD group, 20.6% vs 6.4%, respectively, P<0.001. ECDs with multiple compared with single UC entanglement had higher rate of adverse neonatal outcome, P=0.031, and more placental fetal vascular lesions 19.3% vs 8.1%, P=0.027, respectively.

CONCLUSION

Multiple UC entanglements, true knots and short cords were more common in ECDs for NRFHR, suggesting their role in the development of fetal placental vascular lesions and adverse neonatal outcome.

Effect of Umbilical Cord Entanglement and Position on Pregnancy Outcomes

Introduction. To investigate the effect of complex umbilical cord entanglement primarily around the trunk on pregnancy outcomes. Methods. We studied 6307 pregnant women with singleton pregnancies who underwent vaginal delivery of an infant at ≥37 weeks of gestation. Cases were classified into no cord, nuchal cord, and body cord groups and defined as cases without umbilical cord entanglement, one or more loops of the umbilical cord around the neck only, and umbilical cord around the trunk only, respectively. Pregnancy outcomes were compared among these three groups. Results. The no cord, nuchal cord, and body cord group included 4733, 1451, and 123 pregnancies, respectively. Although delivery mode was not significantly different among the three groups, 1-minute Apgar scores <7 and umbilical artery (UA) pH <7.10 were significantly more common in the umbilical cord entanglement groups than in the no cord group. In particular, the frequency of 5-minute Apgar scores <7 was significantly higher (P = 0.004), whereas that of UA pH <7.10 tended to be higher (P = 0.057) in the body cord group than in the nuchal cord group. Conclusion. Compared to nuchal cord, umbilical cord entanglement around the trunk was associated with a higher risk of low Apgar scores and low UA pH.