Background: Rh isoimmunization is a condition that occurs when a woman with Rh negative blood type becomes sensitized to Rh positive blood cells during childbirth, miscarriage, abortion, medical procedures like invasive prenatal testing (e.g., amniocentesis) trauma to the abdomen during pregnancy or transfusion with Rh positive blood. With each successive pregnancy, there is a cumulative effect of fetomaternal transfusions thus increasing the severity of the problem at hand. It can lead to hemolytic disease of the newborn which can range from mild to severe, including features such as anemia, jaundice, hepatospleenomegaly, and, in severe cases, hydrops fetalis. Such newborns may require treatments such as phototherapy for jaundice, blood transfusions, IV immunoglobulins, and in severe cases, exchange transfusions. Aim: To study the role of cord bilirubin as a non invasive, early predictive marker of hemolysis in Rh positive neonates delivered to Rh negative mothers. Study Type and Design: Observational, descriptive, longitudinal study. Materials: Rh positive neonates delivered in OT/labor room of our hospital to Rh negative mothers studied according to specific protocol. Study Setting: Neonatal and postnatal wards of a rural tertiary care hospital. Period of Study: (Two years) From June 2022 to June 2024. Ethical Committee consent was taken at the start of the study. Data was entered in excel sheets and analyzed using IBM SSPS Statistics software. Results: Out of 277 neonates delivered at term to Rh negative mothers in the study duration, 158 were Rh positive and 119 were Rh negative mothers. A cord bilirubin cutoff of >1.9 mg/dL was found to have excellent specificity (97.8%) and positive predictive value (95.74%), making it a robust tool for identifying newborns at high risk of hyperbilirubinemia, with a sensitivity of 67.16% and a negative predictive value of 80.18%. For the phototherapy group, the average cord bilirubin level was found to be 2.13 ±0.51 mg/dL, as compared to the no phototherapy group, wherein the average cord bilirubin level is 0.80±0.58 mg/dL. Cord bilirubin values >1.9 mg/dl (seen in 29.7% of the study population) were found to have a statistically significant association with a need for interventions (phototheraphy and/or exchange transfusion) with a p value <0.05. Conclucion: Hemolysis due to Rh isoimmunization is more frequent and severe in neonates of multigravida mothers as Zompared to neonates of primigravida mothers, due to the cumulative effect of fetomaternal transfusions in each successive pregnancy. Cord sampling proves to be an essential predictive marker of the risk of hemolysis in the neonate earlier to allow for early initiation of therapeutic measures and reducing the risk of rapid hemolysis and further, long term complications such as bilirubin encephalopathy, emerging as a cornerstone of non invasive care.
Hemolytic disease of the newborn (HDN) due to Rh isoimmunisation is a major cause of perinatal morbidity & mortality. Fetomaternal bleeding occurs anytime during pregnancy and during delivery independent of presence or absence of any risk factors. In the maternal circulation, fetal RBCs are destroyed by the reticuloendothelial system. Initially,
IgM antibodies are produced. These are short lived and cannot cross the placenta. So immunization during the first pregnancy is unlikely. When second exposure to Rh positive antigens occur , immunologically competent cells produce anti D antibodies. Detectable antibodies develop after 6 months following larger volume of fetomaternal blood[1].
Cord bilirubin levels, when employed appropriately in the context of Rh incompatibility, can provide significant advantages in terms of minimizing blood sampling and enabling early diagnosis of hemolytic disease of the newborn.
It can provide a window into the degree of hemolysis occurring in the newborn due to Rh incompatibility. Elevated levels suggest significant hemolysis, prompting early monitoring and timely interventions exemplifying the art of less invasive care.
Using cord bilirubin as a diagnostic tool can streamline care, reducing unnecessary investigations in low risk newborns and concentrates resources on high risk infants who need closer monitoring and treatment.
Neonates can benefit from prompt interventions, avoiding complications like severe anemia or neurological damage.
The study aims to study the role of cord bilirubin values in the assessment of Rh incompatibility.
Study Type and Design: Observational, descriptive, longitudinal study.
Materials: Rh positive neonates delivered in OT/ labor room of our hospital to Rh negative mothers studied according to specified protocol.
Study Setting: Neonatal and postnatal wards of DBVP RMC, PIMS (DU) Loni and VVP PRH, Loni
Period of Study: (Two years) From June 2022 to June 2024.
Type of sampling: Purposive Sampling.
Sample size: 154.
Inclusion Criteria
Exclusion Criteria
These are the results of a descriptive longitudinal study involving inborn, Rh positive neonates delivered at term to Rh negative mothers in the duration of June 2022 to June 2024.
Total deliveries in the study period: 21609
Neonates delivered at term to Rh negative mothers: 277
Rh positive neonates delivered at term to Rh negative mothers: 158 (Study Population)
Table 1: Distribution of Blood Types (Rh) of Neonates of Rh-Negative Mothers:
Baby Rh group |
Rh positive |
Rh Negative |
Distribution n (%) |
158 (57.04%) |
119 (42.9%) |
Table 2: Relation of Cord Bilirubin According to Gravidity:
|
Cord bilirubin>1.9 (mg/dl) |
Cord bilirubin≤1.9 (mg/dl) |
Totals |
Multigravida mother |
38 |
27 |
65 |
Primigravida mother |
9 |
84 |
93 |
Totals |
47 |
111 |
158 (Grand Total) |
The chi-square statistic is 43.5702. The p-value is < 0.00001. Significant at p < .05.
Graph 2: Relation of Cord Bilirubin According to Gravidity:
Among multigravida mothers: 38 cases had cord bilirubin levels >1.9 mg/dl and 27 cases had cord bilirubin levels ≤1.9 mg/dl.
Among primigravida mothers: 9 cases had cord bilirubin levels >1.9 mg/dl and 84 cases had cord bilirubin levels ≤1.9 mg/dl.
This suggests that being a Rh negative multigravida mother is associated with a higher risk of higher cord bilirubin levels (>1.9 mg/dl) of the Rh positive neonate compared to primigravida mothers.
Table 3: Relation Between Cord Bilirubin and Phototherapy Requirement of Rh Positive Neonates of Rh Negative Mothers:
Characteristic |
Phototherapy |
No phototherapy |
Cord Bilirubin (mg/dl) (Mean±SD) |
2.13±0.51 |
0.80±0.58 |
Graph 3: Relation Between Cord Bilirubin and Phototherapy Requirement:
For the phototherapy group, the average cord bilirubin level is 2.13 mg/dL with a standard deviation of ±0.51 mg/dL. This indicates that the bilirubin levels in this group were relatively high as compared to the no phototherapy group, wherein the average cord bilirubin level is 0.80 mg/dL with a standard deviation of ±0.58 mg/dL. This indicates that the bilirubin levels in this group were significantly lower on average and had a slightly wider variation.
Table 4: Cord Bilirubin Distribution:
Cord Bilirubin (mg/dl) |
<1.9 |
1.9 |
>1.9 |
|
104 (65.8%) |
7 (4.4%) |
47 (29.7%) |
Graph 4: Cord Bilirubin Distribution:
Most cord bilirubin levels were <1.9 mg/dl (65.8%).
Table 5: Predictive Value of Cord Bilirubin Cutoffs for Hemolysis in the Neonate:
Cut off bilirubin |
Sensitivity (%) |
Specificity (%) |
Positive Predictive Value (%) |
Negative Predictive Value (%) |
>1.9 mg/dl |
67.16 |
97.8 |
95.74 |
80.18 |
Table 6: Cord Bilirubin Cutoffs to Predict Need for Phototherapy:
|
Phototherapy |
No phototherapy |
Totals |
Cord bilirubin >1.9 mg/dl |
45 |
2 |
47 |
Cord bilirubin ≤1.9 mg/dl |
22 |
89 |
111 |
Totals |
67 |
91 |
158 (Grand Total) |
The chi-square statistic is 77.9345. The p-value is < 0.00001. Significant at p < .05.
Graph 6: Cord Bilirubin Cutoffs to Predict Need for Phototherapy:
There is a clear association between higher cord bilirubin levels (>1.9) and the need for phototherapy.
This study suggests that higher cord bilirubin levels (>1.9 mg/dl) are strongly associated with a higher likelihood of requiring phototherapy, whereas lower levels (≤1.9 mg/dl) are less likely to necessitate phototherapy intervention.
Table 7: Cord Bilirubin to Predict Need for Exchange transfusion:
|
Exchange transfusion |
No Exchange transfusion |
Totals |
Cord bilirubin >1.9 mg/dl |
8 |
39 |
47 |
Cord bilirubin ≤1.9 mg/dl |
2 |
109 |
111 |
Totals |
10 |
148 |
158 (Grand Total) |
The chi-square statistic is 12.9008. The p-value is .000328. Significant at p < .05.
Cord bilirubin >1.9 mg/dL: 17.0% (8/47) of cases required exchange transfusion. The remaining 83.0% (39/47) did not.
Cord bilirubin ≤1.9 mg/dL: Only 1.8% (2/111) of cases required exchange transfusion. A majority of 98.2% (109/111) did not.
A p value of 0.000328 shows a very high level of confidence that the observed relationship is not due to random chance. Hence, our study shows that newborns with cord bilirubin >1.9 mg/dL are much more likely to undergo exchange transfusion compared to those with cord bilirubin ≤1.9 mg/dL.
In this study we have extensively studied the use of cord bilirubin to provide an instant snapshot of the degree of hemolysis occurring in the newborn and its predictive value in Rh positive neonates of Rh negative mothers who may require monitoring and early intervention to prevent long term adverse effects.
Our study shows a statistically significant, positive correlation between higher cord bilirubin values and need for prompt interventions like phototherapy and exchange transfusion, thus the neonates involved can benefit from cord sampling, avoiding complications like severe anemia or neurological damage. This result is similar to that seen in various studies such as,Taksande et al[2], Sun et al[3] and Kumaran et al[4].
This study uses a cutoff cord bilirubin value of >1.9 mg/dl as a predictor of hemolysis in the study population.
|
Cut off bilirubin (mg/dl) |
Sensitivity (%) |
Specificity (%) |
Positive Predictive Value (%) |
Negative Predictive Value (%) |
Knudsen et al. 1989[5] |
>2.35 |
13 |
99 |
85 |
72 |
Taksande et al. 2005[2] |
>2 |
89.5 |
85 |
38.8 |
98.7 |
Sun et al. 2007[3] |
>2 |
68 |
|
45 |
|
Nahar et al. 2009[6] |
>2.5 |
77 |
98.6 |
|
96 |
Satrya et al 2009[7] |
>2 |
90.5 |
85 |
|
|
Bharath et al. 2011[8] |
>2.15 |
73 |
74 |
26 |
90 |
Ahire et al. 2012[9] |
>3 |
100 |
98.7 |
66.67 |
100 |
Kumaran et al. 2016[4] |
>2 |
90.4 |
75.1 |
37.2 |
97.9 |
Pahuja et al 2016[10] |
>2 |
78.3 |
41.9 |
75 |
46.4 |
Present study |
>1.9 |
67.16 |
97.8 |
95.74 |
80.18 |
The studies show varying levels of sensitivity, specificity, PPV, and NPV for cord bilirubin as a predictor of hemolysis in neonates. Our study has a lower cut off value but maintains high specificity and PPV, indicating it is effective in identifying true positive cases of hemolysis while maintaining a good balance of sensitivity and NPV. This suggests that while some differences in cut off values and predictive abilities exist, the present study's methodology provides reliable diagnostic value for predicting the risk of hemolysis in neonates with the use of cord bilirubin, helping in allocating resources for appropriate and early management of the child to prevent long term complications.
With our study, we have attempted to elucidate the value of cord blood sampling for bilirubin. Bilirubin can be non invasively and effortlessly measured immediately after delivery from the umbilical cord, eliminating the need for discomfort from postnatal venipuncture.
Using cord bilirubin to streamline risk stratification, while reduce unnecessary investigations involving multiple, painful blood samplings in low risk newborns, is essential for appropriate resource allocation for high risk infants needing prompt interventions.
It can also offer an instant snapshot of the degree of hemolysis occurring in the newborn due to Rh incompatibility, emerging as a cornerstone of neonatal management. Elevated levels suggest significant hemolysis, allowing early monitoring and timely intervention such as phototherapy and exchange transfusion, before bilirubin levels reach dangerous thresholds.
Since we can thus foreshadow disease progression, neonates can benefit from tailored and prompt interventions, avoiding complications like severe anemia or neurological damage (kernicterus).
When combined with other cord blood tests (e.g., Direct Coombs Test, hemoglobin levels), it can be used for assessment of Rh incompatibility, epitomizing a sophisticated approach towards non invasive care.