Prenatal measurement of umbilical cord length using magnetic resonance imaging

Fetal Aortic and Umbilical Doppler Flow Velocity Waveforms in Pregnancy: The Concept of Aortoumbilical Column

Low impedance within the uteroplacental circulation is crucial for fetal development. Flow velocity waveforms (FVW) have been established for the aortic and umbilical arteries in low-risk pregnancies during the second half of pregnancy, but data regarding early gestation is limited. Both vascular territories exhibit higher impedance patterns in pregnancies complicated by fetal growth restriction (FGR), hypertensive disorders, fetal anemia, and chromosomal abnormalities. Early identification of these complications is critical in obstetric practice, to reduce perinatal morbidity and mortality through prevention and close antenatal surveillance. Available data suggest that aortic and umbilical impedances follow the same variation pattern as pregnancy progresses. This observation implies that both vessels may be considered as a single artery, referred to as the "aortoumbilical column". Our hypothesis posits that changes in the hemodynamic pattern of this column could identify high-risk pregnancies, particularly those complicated by preeclampsia, FGR, intrauterine fetal demise, fetal aneuploidies, and fetal anemia. Understanding vascular embryogenesis and the FVWs of the aortic and umbilical arteries enables comprehension of impedance changes throughout normal pregnancies. The continuous variation in impedance along a single vessel supports our concept of the aortoumbilical column. Deviations from the regular pattern could assist in identifying compromised fetuses during early pregnancy. Further research on normal aortoumbilical column FVW and the development of reference charts is necessary to consider this arterial column as a screening tool in clinical practice.

Current Perspectives of Prenatal Sonography of Umbilical Cord Morphology

The umbilical cord constitutes a continuation of the fetal cardiovascular system anatomically bridging between the placenta and the fetus. This structure, critical in human development, enables mobility of the developing fetus within the gestational sac in contrast to the placenta, which is anchored to the uterine wall. The umbilical cord is protected by unique, robust anatomical features, which include: length of the umbilical cord, Wharton’s jelly, two umbilical arteries, coiling, and suspension in amniotic fluid. These features all contribute to protect and buffer this essential structure from potential detrimental twisting, shearing, torsion, and compression forces throughout gestation, and specifically during labor and delivery. The arterial components of the umbilical cord are further protected by the presence of Hyrtl’s anastomosis between the two respective umbilical arteries. Abnormalities of the umbilical cord are uncommon yet include excessively long or short cords, hyper or hypocoiling, cysts, single umbilical artery, supernumerary vessels, rarely an absent umbilical cord, stricture, furcate and velamentous insertions (including vasa previa), umbilical vein and arterial thrombosis, umbilical artery aneurysm, hematomas, and tumors (including hemangioma angiomyxoma and teratoma). This commentary will address current perspectives of prenatal sonography of the umbilical cord, including structural anomalies and the potential impact of future imaging technologies.

Maternal obesity and stillbirth at term; placental pathology-A case control study

OBJECTIVE

The aim was to explore the potential role of the placenta for the risk of stillbirth at term in pregnancies of obese women.

METHODS

This was a case-control study comparing placental findings from term stillbirths with placental findings from live born infants. Cases were singleton term stillbirths to normal weight or obese women, identified in the Stockholm stillbirth database, n = 264 and n = 87, respectively. Controls were term singletons born alive to normal weight or obese women, delivered between 2002-2005 and between 2018-2019. Placentas were compared between women with stillborn and live-born infants, using logistic regression analyses.

RESULTS

A long and hyper coiled cord, cord thrombosis and velamentous cord insertion were stronger risk factors for stillbirth in obese women compared to normal weight women. When these variables were adjusted for in the logistic regression analysis, also adjusted for potential confounders, the odds ratio for stillbirth in obese women decreased from 1.89 (CI 1.24-2.89) to 1.63 (CI 1.04-2.56).

CONCLUSION

Approximately one fourth of the effect of obesity on the risk of stillbirth in term pregnancies is explained by umbilical cord associated pathology.

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 length affects the efficacy of amnioinfusion for repetitive variable deceleration during labor

Objectives: Although amnioinfusion (AI) for repetitive variable deceleration has been reported to reduce the frequency of variable deceleration and cesarean section (CS) rate, CS is sometimes unavoidable even after therapeutic AI. The purpose of this study was to investigate prenatal factors related to the efficacy of therapeutic AI during labor.Methods: This retrospective study investigated 80 singleton pregnancies that underwent transcervical therapeutic AI for repetitive variable deceleration during labor. AI was performed with 500 mL of warmed saline through an intrauterine pressure catheter by gravity infusion. Prenatal factors related to emergency CS for fetal distress even after therapeutic AI were investigated.Results: Emergency CS was performed for 12 of the 80 cases due to fetal distress. Z-score for umbilical cord length was significantly smaller in the CS group (-0.68 SD) than in the vaginal delivery group (0.15 SD, p < .001). No CSs were performed in cases with Z-score for umbilical cord length >-0.05 SD. No significant differences between CS and vaginal delivery groups were seen in gestational age at delivery, cervical dilatation at AI, birth weight, Z-score of birth weight, incidence of the nuchal cord or incidence of abnormal umbilical cord insertion.Conclusions: Therapeutic AI for repetitive variable deceleration was considered useful, in many cases avoiding emergency CS. Short umbilical cord length (lower Z-score) was related to emergency CS after therapeutic AI for repetitive variable deceleration. Umbilical cord length may offer an important factor for assessing the risk of fetal distress that is difficult to avoid, if methods to accurately determine umbilical cord length can be developed.