The only possible connection between the placenta and the growing fetus is the umbilical cord, which is necessary to provide the developing fetus with a continuous supply of oxygen, nutrients, and ensures the release of waste material that was built up during the period of in utero growth. The cord usually has a helical or coiled shape and is composed structurally of two umbilical arteries and a single umbilical vein surrounded by Wharton jelly. The Umbilical Coiling Index (UCI) is a measure of this pattern of coiling quantified by measuring the distance in centimetres between two consecutive coils of the vascular system viewed on ultrasound in the second trimester of pregnancy and taking the reciprocal. Normal UCI values measure about 0.21 24 coils per centimetre, and hypocoiling is less than the 10th percentile and hypercoiling is greater than the 90 th percentile[1,2].

The use of UCI has drawn enormous interest since it offers a unique non-invasive indicator of fetal well-being. It is postulated that aberrant coiling patterns are related to fetal growth restriction and poor intrapartum outcomes. Hypocoiled cords are linked to higher frequencies of preterm birth, low birth weight, and fetal distress as well as delivery to the neonatal intensive care unit, whereas hypercoiled cords are linked to intrauterine growth constraint, oligohydramnios as well as operative delivery[3,4]. These associations are further supported by postnatal studies that showed considerable associations between extreme UCI values with unfavorable perinatal outcomes of low Apgar scores and perinatal mortality[5].

Alongside UCI assessment, Doppler ultrasonography monitors hemodynamic rules of the umbilical vessels. Umbilical artery Doppler indices such as systolic/diastolic ratio, resistance index, and pulsatility index remark placental vascular resistance and fetal perfusion during the second trimester. Whereas initial studies showed no significant association between UCI and arterial Doppler indices, newer studies indicate that UCI is positively correlated with umbilical vein blood flow and velocity indicating that coiling increases venous return and could be used as a buffer against hemodynamic alterations[2,6]. This association highlights the practical importance of cord architecture that is more than structural morphology.

Owing to the frequent use of detailed anomaly scans during week 18-22 of gestation, secondary care centers offer an ideal locus to include UCI and Doppler assessment in the perinatal risk stratification systems. In these settings, future observational studies state that abnormal second-trimester UCI has been shown to signal adverse events such as meconium-stained amniotic fluid, abnormal fetal heart rate pattern, and high rates of cesarean delivery[7,8]. Combining these evaluations can guide an increased surveillance approach, such as routine growth scans and preplanned interventions, with a possible reduction in perinatal morbidity and mortality.

Considering the evidence between UCI in the second trimester, Doppler features and perinatal outcomes, it is of paramount importance that UCI be standardized in the context of level II ultrasound scans. Determining reference percentiles in particular populations and matching them to Doppler parameters will fine tune predictive accuracy. Multicenter studies in the tertiary care sector should attempt to authenticate the cutoff figures of hypocoiling and hypercoiling, the additive prognostic input of the combined UCI Doppler modes, and the occurrence of better neonatal outcomes by an early recognition and intervention into high-risk cases.

Study design

This was a hospital-based, time-bound, and Prospective Analytical Study study done in the Department of Radiodiagnosis of M.G.M. Medical College and M.Y. Hospital, Indore, Madhya Pradesh, India after getting approval by ISRB (Institutional Scientific Review Board). The duration of this study was one year from ethics committee clearance. The aim of study was to establish the relationship between the umbilical cord coiling and umbilical vein blood flow with pregnancy outcome.

Study setting and duration

The study was carried at department of radiodiagnosis of M.G.M. Medical College and M.Y. Hospital, Indore, Madhya Pradesh. The study was conducted over period of one year.

Study population

A total of 200 patients referred to our department for antenatal scan between 18 weeks to 28 weeks were included in the study. Pregnant female who provided informed consent.

INCLUSION CRITERIA –

The pregnant women with singleton pregnancy between 19 and 40 years of age were included in this study.

Exclusion criteria:

All high risk pregnancies like gestational hypertension , gestational diabetes mellitus ,anemia , RH negative pregnancies and other complications. 2. Multiple gestation 3. Single umbilical artery/placental anomaly.

Sampling technique

Simple random sampling was employed to select the study participants.

Data collection procedure

After completing the PC-PNDT Act formalities, obstetric ultrasound was performed. 4. All patients were examined in supine position using a low frequency transducer (3-5 MHz) in Samsung USG machine RS80.

Fetus was observed for viability, gestational age and gross congenital  defect.  Antenatal Umbilical Coiling Index was calculated as reciprocal value of distance between pair of coils measured from inner edge of arterial or venous wall to outer edge of next coil along the ipsilateral side of umbilical cord, direction of coiling is from placental end to fetal end.the final value is the average of 3 readings at 3 different segments in the free floating cord.

UCI = 1/distance in between adjacent pair of coils in cm.

We calculated percentile of UCI for study population the pregnant women with UCI between 10th and 90th percentile were taken as normocoiled, below 10th percentile were taken as hypocoiled and above 90th percentile were taken as hypercoiled.

Umbilical vein blood flow was calculated when the fetus was in quicent state without any fetal body movements in free floating segment of umbilical cord. Color doppler examination was done and angle was kept below 20°. The umbilical vein internal diameter was taken in longitudinal section of cord by caliper measurement and umbilical vein blood velocity (UV) was measured.

Umbilical cord blood flow was calculated as ml/min/kg = π (UVD x 0.5)^₂ x UV / EFW UV : umbilical vein velocity cm/sec UVD : umbilical vein diameter in mm EFW: effective fetal weight in kg 10. We calculated percentile of Umbilical cord blood flow for study population the pregnant women with Umbilical vein blood flow between 10th and 90th percentile were taken as normal, below 10th percentile were taken as decreased and above 90th percentile were taken as increased.Post-delivery birth weight of the baby, Apgar score, and NICU admissions were noted.

Data analysis

Data from all the visits were tabulated in Microsoft Excel sheet for analysis. 13. Further depiction of data was done in the form of tables and charts. SPSS was used to analyse the data.

Table 1 distribution of patients according to age

The table shows age distribution among 200 patients: 23% were aged 18–22, 32% aged 23–27, 30.5% aged 28–32, 12.5% aged 33–37, and 2% aged 38–42.

Table 2 Frequency distribution of hypercoilin gandhy Po coiling with perinatal outcomes

Table 2 presents perinatal outcomes associated with abnormal umbilical coiling index (UCI). Among hypercoiled and hypocoiled cases, hypocoiling showed higher rates of preterm deliveries, low APGAR scores, and low birth weight. NICU admissions were slightly more common in hypercoiled cases. Intrauterine deaths occurred only in the hypocoiled group.

Table 3 Association of abnormal coiling index with perinatal outcome.

Table 3 shows the association between abnormal and normal umbilical coiling index (UCI) with perinatal outcomes. Abnormal UCI is linked to higher rates of preterm delivery, low birth weight, and low APGAR scores.

Table 4 Frequency distribution of Abnormal Umbilicalve in flow with perinatal outcomes

Table 4 illustrates the relationship between abnormal umbilical vein flow and perinatal outcomes. Decreased flow is associated with higher rates of preterm delivery, low birth weight, low APGAR scores, and LSCS. No intrauterine deaths were observed. NICU admissions were slightly more frequent in the decreased flow group, indicating adverse outcomes.

Table 5 Association of abnormal umbilical vein blood flow and perinatal outcomes

Table 5 compares perinatal outcomes between abnormal and normal umbilical vein blood flow groups. Abnormal flow is linked to a higher proportion of preterm births and low birth weight, LSCS, low APGAR scores, and NICU admissions.

Table shows the distribution of 200 participants based on Umbilical Coiling Index (UCI). Most were normocoiled (76.5%), followed by hypocoiled (<0.21) at 12%, and hypercoiled (>0.59) at 11.5%. This indicates that the majority had a normal UCI, with fewer showing abnormal coiling patterns

Case 1 : A case of 26 years old second gravida 23 weeks 2 day of gestation with effective fetal weight 410grams.

Fig: a                                                                      Fig: b

Fig: c                                                                      Fig: d

Figure a : B mode image of umbilical cord.

Figure b : Umbilical coiling index = 0.52, Normocoiled.

Figure c : umbilical vein diameter 0.41cm.

Figure d : umbilical vein velocity 8.98cm/sec.

Umbilical vein flow = 251cm/sec/kg which is normal.

Case 2 : A case of 22 years old primi gravida 24 weeks 2 day of gestation with effective fetal weight 400grams

Fig : a                                                               Fig : b

Fig : c                                                                Fig : d

Figure a : B mode image of umbilical cord.

Figure b : Umbilical coiling index = 0.62, Hypercoiled.

Figure c : umbilical vein diameter 0.38 cm

Figure d : umbilical vein velocity 10.75cm/sec.

Umbilical vein flow = 303cm/sec/kg which is normal

The present study of 200 patients demonstrated that 76.5% had a normal second-trimester Umbilical Coiling Index (UCI), while hypocoiling and hypercoiling accounted for 11.0% and 12.5%, respectively. Hypocoiling was associated with higher rates of preterm delivery (32% vs 12% normocoiled), low birth weight (LBW; 60% vs 18%), low 5-minute APGAR (<7; 48% vs 8%), NICU admission (42% vs 10%) and all recorded intrauterine deaths. Hypercoiling showed fewer adverse events but still elevated NICU admissions (18% vs 10%), aligning with earlier research that hypercoiled cords have a modestly increased risk of operative delivery and respiratory distress[9].

Umbilical vein flow (UVF) abnormalities likewise predicted perinatal compromise. Decreased UVF correlated with greater preterm delivery (28% vs 14%), LBW (52% vs 24%), low 5-minute APGAR (36% vs 12%) and higher NICU admissions (30% vs 14%), whereas increased UVF had milder associations. These findings mirror De Laat et al., who reported that reduced UVF/AC near term significantly predicted adverse perinatal outcome (aOR 0.53; 95% CI 0.30–0.87)[10], and a multicenter cohort showing UVF ≤0.65 MoM heightened risk of iatrogenic preterm birth (aOR 3.5; 95% CI 1.0–11.8)[11].

The age distribution of this cohort peaked at 23–27 years (32%), consistent with Strong et al.’s observation of lower complication rates in women aged 18–32[12]. The smaller representation of older mothers suggests potential for age-related outcome differences worthy of investigation, echoing findings that maternal age >35 years may amplify the impact of abnormal UCI on perinatal risk.

Overall, the study’s demonstration that hypocoiling is the most deleterious coiling abnormality aligns with multiple investigations: Pregnan et al. found hypocoiled cords (<10th percentile) significantly increased operative intervention for fetal distress and meconium staining[12], and Chitra et al. linked hypocoiling to preterm labor and hypertensive disorders[13]. Hypercoiling’s association with IUGR and low ponderal index has also been affirmed by Singh et al. and Gupta et al.[9,14].

These corroborations reinforce UCI and UVF as complementary sonographic markers for predicting adverse perinatal outcomes. Incorporating both into second-trimester anomaly scans, particularly in tertiary care settings with high-risk referrals, may enhance early identification of compromised pregnancies and enable timely interventions.

This study demonstrates a positive correlation between umbilical coiling index and maternal and fetal outcome. Abnormal umbilical coiling index and abnormal umbilical vein flow was associated with a higher incidence of pre term delivery, LSCS, low birth weight, poor APGAR scores and NICU admission. So, mothers with antenatal abnormal umbilical coiling index and abnormal umbilical vein flow should deliver at hospitals with good obstetric and NICU care. In conclusion, the second-trimester antenatal UCI and umbilical vein flow characteristics offer valuable insights into fetal well-being and can serve as early predictive markers for perinatal outcomes.

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