DIAGNOSTIC APPROACH IN NEONATAL JAUNDICE

Neonatal jaundice may be physiological or pathological due to many causes (Table 12.36). Diagnostic approach in these cases aims to answer following questions:

Step I. Whether it is pathological? Neonatal jaundice is considered as pathological in presence of any of the following features:

• Appears within 24 hours of birth,

• S.

• Persistence of icterus gt; 10^th day (gt;14^th day in preterm),

• Sick child, e.g. vomiting, lethargy, poor feeding, apnoea, hypothermia, etc.

All suspected cases of pathological jaundice require detailed investigation to identify the cause, constant monitoring and timely therapeutic interventions.

Step II. Whether it is predominantly unconjugated or conjugated? Pathological jaundice may be broadly divided in: (a) unconjugated or indirect, or (b) conju­gated or direct hyperbilirubinemia. Conjugated hyper­bilirubinemia is relatively less common and usually manifests beyond 2nd week of life with progressive icterus and typical clay-color stools.

Step III. What is the precise cause? Hemolytic disease of newborn (Rh/ABO incompatibility), septicemia and congenital haemolytic anemia are three leading causes of unconjugated jaundice, while conjugated jaundice usually indicates extrahepatic biliary atresia (EHBA) or neonatal hepatitis. However, other causes (Table 12.40) should be excluded

Step IV. What is the severity? While serial bilirubin level is the best indicator for severity in neonatal jaundice,

TABLE 12.36: Causes of neonatal jaundice

• Physiological

• Pathological (predominantly unconjugated)

- Overproduction of bilirubin

#9830; Hemolytic disease of newborn (Rh/ABO)

#9830; Congenital hemolytic anemia:

#9632; Membrane defects, e.g. H. spherocytosis

#9632; Enzyme defects, e.g. G6PD deficiency

#9632; Hemoglobinopathies, e.g.

#9830; Acquired hemolysis due to

#9632; Polycythemia

#9632; Cephalohematoma

#9632; Intrauterine infections, septicemia

#9632; Drugs: Vitamin K, sulfonamides, etc.

- Impaired hepatic metabolism

#9830; Inherited enzyme defects:

#9632; UDPGT deficiency: Crigler-Najjar syndrome

#9632; Specific Y/Z protein (Ligandin) deficiency

#9632; IEMs: Galactosemia, Gilbert syndrome

#9830; Inhibition of enzyme activity

#9632; Breast-milk jaundice

#9632; Lucey-Driscoll syndrome

#9632; Drugs, e.g. chloramphenicol, aminoglycosides

#9830; Endocrinal disorders: Hypothyroidism

• Pathological (predominantly conjugated)

- Impaired excretion (cholestasis syndromes)

#9830; Neonatal hepatitis

#9632; Idiopathic neonatal hepatitis

#9632; Intrauterine infections

#9632; Metabolic: galactosemia, #945;₁ antitrypsin deficiency

#9830; Biliary tract malformations

#9632; Extra-hepatic biliary atresia (EHBA)

#9632; Intra-hepatic biliary atresia (IHBA)

#9632; Choledochal cysts

#9830; Inspissated bile syndrome

#9830; Inherited: Dubin-Johnson syndrome

- Increased enterohepatic circulation

#9830; Intestinal stasis: IHPS, meconium ileus

#9830; Poor gut flora: Delayed feeding, prolonged antibiotics

IHPS: Infantile hypertrophic pyloric stenosis

Table 12.37 provides a commonly used quot;Kramer criteriaquot; for clinical assessment of severity.

A diagnostic algorithm for neonatal jaundice is given in Fig. 12.16, though important diagnostic clues are as follows:

Clinical evaluation, with special reference to:

• Age of appearance (Table 12.38)

Fig. 12.16: Diagnostic algorithm for N. hyperbilirubinemia.

*For example, paralytic ileus, late feeding, intestinal obstruction

- Hemolysis screen: Hct, Hb and P. smear

- Sepsis screen: TLC, band-cell count, CRP

• Investigations in indirect hyperbilirubinemia

- Serological tests for intrauterine infections

- Hb electrophoresis, osmotic fragility, G6PD esti­mation for congenital hemolytic anemia.

- Metabolic screening for enzyme defects

• Investigations in direct hyperbilirubinemia

- Hepatobiliary scan

- Liver biopsy

12.14.2 UNCONJUGATED HYPERBILIRUBINEMIA

Unconjugated hyperbilirubinemia is a major cause of concern in early neonatal period, due to potential risk of neurotoxicity. Hemolytic disease of newborn (HDN) due to Rhesus or ABO blood group incompatibility is the commonest cause of severe unconjugated hyperbilirubinemia. Followed by breast milk jaundice and Crigler-Najjar syndrome, etc. Minor blood group incompatibilities, though probably more common, rarely produce significant hemolysis.

TABLE 12.38: Age of onset in neonatal jaundice

• Within 24 hours of Birth

- Hemolytic disease of newborn (Rh/ABO)

- Intrauterine infections

- Cong. hemolytic anemia, e.g. thalassemia major

- Maternal medications, e.g. Vit K, sulfonamides, etc.

- Crigler-Najjar syndrome

• Between 24 and 72 hours

- All of the above, plus

- Physiological jaundice

- Exaggerated physiological jaundice

- Neonatal sepsis

• Between 72 hours and 14^th day

- All of the above, plus

- Breast milk jaundice

- Septicemia

- Gut stasis/sterilization: IHPS, antibiotic therapy

• Beyond 14^th day of life

- Neonatal hepatitis (idiopathic, secondary)

- Biliary atresia (EHBA/IHBA)

IHPS: Infantile hypertrophic pyeloric stenosis

• Duration of icterus: Persistent icterus gt; 2 weeks may be due to hypothyroidism, Crigler-Najjar syndrome, neonatal cholestasis disorders, or inspissated bile syndrome.

• Perinatal problems, e.g. preterm, asphyxia, sepsis.

• General appearance and activity level.

• Type of feeding (breast milk jaundice).

• Exposure to drugs causing hyperbilirubinemia

Laboratory evaluation include:

• Baseline investigations in all cases

- Serum bilirubin levels (total and direct)

- Blood grouping (ABO/Rh type)

Rhesus hemolytic disease of newborn (Rh-HDN) is characterized by severe hemolysis of fetal RBCs in a Rh +ve fetus/newborn born to Rh-ve mother, due to transplacental transfer of maternal anti-D (anti-Rh) antibodies. In India, ~5% of mothers are Rh-negative. Rh blood group system is characterized by three antigens, i.e. C, D and E. Of these, D is the most important antigen and hence, anti-Rh antibodies are also commonly termed as anti-D antibodies.

Pathogenesis: There are no inborn anti-Rh antibodies in humans and production of anti-D antibodies in mother requires sensitization of her immune system by exposure to Rh +ve antigen. Usually, this sensitization occurs during first trimester by seepage of Rh+ve fetal RBCs to maternal side via immature placenta, which stimulates maternal anti-D IgG production. However, initial sensi­tization may also occur during previous deliveries, abortions/stillbirths or Rh +ve blood transfusions.

These antibodies, mainly of IgG class, cross the placental barrier to produce hemolysis of fetal RBCs Since the quantum of these antibodies depends on frequency of antigenic exposure, first babies are less affected than subsequent births.

Clinical spectrum of Rh-HDN varies from insignificant hemolysis to the severe hemolytic anemia in fetal life, leading to hydrops fetalis and stillbirth. Severity tends to increase with increasing birth order.

Erythroblastosisfetalis, the commonest presentation of Rh-HDN, manifest with two cardinal features: (a) moderate to severe hemolytic anemia at birth, and (b) appearance of icterus within first 24 hours. Untreated cases may rapidly progress to reach dangerously high

TABLE 12.39: Causes of hydrops fetalis

Immune hydrops: Hemolytic disease of newborn

Non-immune hydrops:

• Severe anemia: a-thalassemia, G6PD deficiency

• Renal malformations, e.g.

• Pulmonary aplasia/hypoplasia

• Intrauterine infections: Syphilis, CMV

• Chromosomal: Down syndrome

• Placental AV malformations

bilirubin levels and consequent neurotoxicity, i.e. kernicterus. Other complications, e.g. hypoglycemia, CCF are common.

Hydropsfetalis: Most severe presentation, is characte­rized by—(a) severe anemia, (b) generalized anasarca with ascites/pleural effusion and (c) hepatosplenomegaly at birth. Most cases die in utero or soon after birth and must be differentiated from other causes of non-immune hydrops fetalis (Table 12.39).

Diagnosis rests on Rh-group setting (Rh +ve baby born to Rh-ve mother), though the severity of hemolysis and extent of hyperbilirubinemia should be monitored both, antenatally as well as postnatally.

Antenatal assessment of severity is indicated in high- risk Rh-ve mothers with history of previous transfusions, abortions, stillbirths or Rh +ve delivery. This requires periodic estimation of maternal anti-D titers. Those with high titers need assessment of optical density of amniotic fluid, from 24^th week onwards, every 2-3 weeks. An optical density difference of gt;0.1 from previous value or consistent rise on consecutive analysis, indicate severe hemolysis.

At the time of birth, cord blood should be collected in all babies of Rh-ve mothers, for grouping, Hb/Hct, direct Coombs' test and S.bilirubin levels. A positive direct Coombs' test confirms the diagnosis, though it may be false -ve, if sample is contaminated by Wharton's jelly.

Postnatally, symptomatic cases should be monitored by serial Hb, Hct and S. bilirubin levels, to decide the severity and further management. Peripheral smear is another indicator of on-going hemolysis, showing reticulocytosis, normoblasts and other immature cells.

Prevention of Rh-HDN involves:

• Pre-conceptional counseling with Rh-testing,

• Avoid mismatch transfusions in Rh -ve mothers,

• Anti-D immunoglobulins to mother within 72 hours of each delivery/abortion.

Although the dose of anti-D depends on the extent of expected feto-maternal leak, 250 mg is usually enough to protect against most cases with ~10 ml of feto-maternal hemorrhage.

Management of Rh-HDN aims to prevent: (a) severe anemia, and (b) bilirubin toxicity, e.g. kernicterus.

• Antenatal management of severe intrauterine HDN involves repeated fetal transfusions of 50 ml Rh-ve packed RBCs, via cordocentesis under USG guidance, till delivery.

• Postnatal management depends on the severity of hyperbilirubinemia, using two important inter- ventions-phototherapy or exchange transfusion, discussed later in this chapter.

Apart from critical bilirubin levels (Table 12.44), early exchange transfusion is also indicated in Rh-HDN with—

(a) cord bilirubin gt;5 mg/dl, (b) Cord Hb lt;10 mg/dl, (c) bilirubin rise gt;1 mg/dl/hr despite phototherapy, and (d) S. bilirubin gt;20 mg/dl at any age.

Intravenous immunoglobulin (0.5-1.0 g/kg/dose; repeat in 12 hr) is a useful adjunctive therapy to phototherapy in Rh-HDN to reduce the need for exchange transfusion. ABO-Hemolytic disease (ABO-HDN) is emerging as a major cause of neonatal hyperbilirubinemia after relative control of Rh-HDN by anti-D prophylaxis.

Pathogenesis: Isohemagglutinin IgG antibodies are nearly always present in mothers against the ABO antigen, which is absent on her own RBCs (Group 'O' mothers have both anti-A and B antibodies, while group 'A' and 'B' mothers have anti-B or anti-A antibodies respectively). When a fetus with different ABO group is conceived, these IgG antibodies cross placenta to cause hemolysis of fetal RBCs. However, as there is no active stimulation of maternal antibody production unlike Rh-HDN and only pre-formed antibodies are transferred, hemolysis is less severe. Although ABO incompatibility is present in gt;25% deliveries, only lt;10% manifest clinically.

Clinical manifestations are most severe in settings of 'O' mother and 'A' or 'B' baby. ABO-HDN is more common in females and more severe in first-born baby. Unlike Rh- HDN, Severity of ABO-HDN tends to decrease in subsequent deliveries. Jaundice usually appears after 24 hours, peaks less than in Rh-HDN and phototherapy is often enough, with less need for exchange transfusions.

Diagnosis depends on feto-maternal ABO mismatch and signs of hemolysis on peripheral smear. Direct Coombs' test is negative.

Management is same as for Rh-HDN or other causes of indirect hyperbilirubinemia, guided by serum bilirubin levels.

Breast milk jaundice is seen in ~2% of breastfed babies, who are otherwise healthy.

Etiology: Exact etiology of breast milk jaundice is unclear, though probably relates to: (a) Presence of 3-20#946; pregnanediol, unsaturated fatty acids or unknown substances in human-milk, which inhibit hepatic conjugation; or (b) increased enterohepatic circulation, due to presence of â-glucuronidase in breast milk.

Clinically these newborns are otherwise fullterm, healthy and active. Jaundice develops during first week of lifelike

physiological jaundice but rather than disappearing by 7-10 day, it deepens gradually to peak by 2-3 weeks (max S. bilirubin as high as 10-30 mg/dl), followed by gradual reduction and disappearance by 3-12 weeks, even if breastfeeds are continued.

Diagnosis depends on exclusion of other causes and typical healthy, active baby, despite deep jaundice. In a suspected case, it may be confirmed by temporary stoppage of breastfeeds, which brings down the bilirubin levels rapidly with 48-72 hours. These levels may rise again on subsequent resumption of breastfeeding, albeit marginally and less than previous values.

Management: No specific management is required and breastfeeding should be continued even if bilirubin levels reach 20 mg/dl, though phototherapy may be necessary. Supplementing breastfeeds with top-feeds is not advisable, as mixed feeding is known to cause further rise in bilirubin.

Crigler-Najjar syndrome is an inherited enzyme defect, characterized by non-hemolytic unconjugated hyperbilirubinemia due to Glucuronyl Transferase deficiency.

• Type I defect (autosomal recessive), presents with rapidly progressive hyperbilirubinemia since birth and no response to phenobarbitone therapy.

• Type II defect (autosomal dominant) is a milder variant, which presents at any age with mild persistent icterus and unconjugated bilirubinemia. Family history is common. Unlike type I, These cases show rapid decline in bilirubin levels with oral phenobarbitone therapy (3-5 mg/kg/day).

Diagnosis should be considered in any case of unconjugated hyperbilirubinemia in newborn or infant, without evidence of hemolysis or infection. Enzyme estimation is diagnostic, though not easily available.

Management of type I disease is same as for other causes of unconjugated hyperbilirubinemia, i.e. phototherapy/ exchange transfusion, depending on bilirubin levels. Type II disease may be controlled by long-term phenobarbitone therapy, with good prognosis.

Drug-induced j aundice in newborns may be caused by:

• Increased hemolysis and bilirubin production in G6PD deficiency (antimalarials),

• Displacement of conjugated bilirubin from binding sites (sulphonamides, salicylates),

• Competitive inhibition of Y-receptor proteins (vitamin K) or UDPGT (aminoglycosides, chloramphenicol),

• Damage to normal gut flora (neomycin).

Management of Unconjugated Hyperbilirubinemia

Management of unconjugated hyperbilirubinemia. Irrespective of the cause, primarily aims to keep free indirect bilirubin levels within the safe-limits of neuro­toxicity, till spontaneous decline in hemolysis and maturity of liver functions. However, these safe-limits are not well-defined and depend on the gestational age, birth weight and co-existing problems that impair blood-brain barrier (Table 12.45).

Important measures to facilitate bilirubin excretion or limit indirect hyperbilirubinemia include: (a) Photo­therapy, (b) exchange transfusion, and (c) ancillary measures, discussed as follows:

I. Phototherapy is most widely used method to prevent/ treat unconjugated hyperbilirubinemia and avert the need for exchange transfusion.

Principle: In phototherapy, an icteric newborn is exposed to a specific band of light frequency (425-475 nm) that leads to photo-isomerization of neurotoxic unconjugated bilirubin (present in skin) to non-toxic isomers, which are then excreted through normal channels. Phototherapy also reduces bilirubin levels by photo-oxidation as well as by enhancing hepatic excretion of unconjugated bilirubin into intestinal lumen.

Indications for phototherapy depends on total serum bilirubin (TSB) levels and the anticipated risk for neurotoxicity, which itself depends on the gestation, postnatal age and other risk factors (Table 12.40).

American Academy of Pediatrics (2022) has recently updated separate cut-off for TSB levels in infants of different gestations 23 weeks onwards to initiate phototherapy, with or without neurotoxicity risk factors, i.e. presence of haemolytic disease, sepsis, low albumin levels lt;3 gm/dl, etc. and significant clinical instability in preceding 24 hours.

Procedure: Phototherapy is provided by prolonged exposure of baby to the specified frequency of photoemittance under an overhead phototherapy unit, usually using LED lamps at present. Important pre­requisites for effective phototherapy are:

• Light source should provide an irradiance of gt;30 #956;W/ cm²#8725;nm within the 460-490 nm range, at the level of baby's skin (monitor with flux meter). The source should also be covered with a perplex shield to cut-off harmful infra-red rays.

• Distance between baby and light source must be ~ 30-45 cm.

• Baby should be fully uncovered except eyes and genital region, to avoid radiation injury to sensitive organs. Double surface and triple surface phototherapy units are available with marginal benefits.

• Adequate breastfeeding is must to avoid dehydration due to insensible losses. Add 20% extra fluids to maintenance requirements, if baby is on IV fluids.

• Phototherapy is given continuously, except during BF, with intermittent bilirubin monitoring. Intermittent Phototherapy for 6-8 hours (with 2-3 hours gap) though

TABLE 12.40: Cut-off unconjugated bilirubin levels for phototherapy and exchange transfusion (mg/dl)*

as effective as continuous phototherapy, carries poten­tial risk of more DNA damage.

• Monitor body temperature every 2-4 hourly and TSB levels every 12-24 hours.

• Stop phototherapy only when two TSB values are below the cut-off point, though clinical monitoring should continue to check for rebound hyperbilirubinemia. Exposure to sunlight is not an alternative to phototherapy

and may be harmful due to prolonged exposure to UV rays.

Modifications to increase effectiveness of the PT include:

• Double surface phototherapy to expose front as well as back surface of the baby, allows faster reduction in bilirubin levels.

• Intensive phototherapy, i.e. lesser distance between light source and infant (15-20 cm), may be more effective.

• Intermittent phototherapy for 6-8 hours (with 2-3 hours gap) is as effective as continuous phototherapy, though with potential risk of more DNA damage.

Effectiveness of phototherapy depends on: (a) initial bilirubin levels, (b) surface area of exposed skin, (c) gestation/weight of baby, and (d) quality and distance from the light source. Although riboflavin supplements appear to increase its effectivity, it is not commonly used due to probable risk of DNA toxicity.

Complications: Although phototherapy is a safe and non-invasive intervention, following complications may develop in some cases:

• Dehydration due to insensible water loss,

• Loose-green stools due to bilirubin catabolites,

• Hypo/hyperthermia,

• Phototherapy rash,

• Bronze skin discoloration, if erroneously given to a case of conjugated hyperbilirubinemia, due to formation of an isomer - bilifuscin;

• Late effects due to cellular damage to eyes, genitals (sterility) and skin (cancers).

II. Exchange transfusion is the most effective method to reduce indirect bilirubin levels, indicated only in severe hyperbilirubinemia.

Principle: Exchange transfusion aims to: (a) remove partially hemolysed, antigen-coated RBCs as well as unattached antigen from recipient's circulation, (b) replace them by unsensitized donor's RBCs, and (c) reduce circulating bilirubin metabolites

Indications for exchange transfusion include critical TSB levels (Table 12.40), though pre-emptive exchange transfusion may also be considered if cord bilirubin is gt; 5 mg/dl or rising at the rate of gt; 1 mg/dl/hour despite phototherapy.

American Academy of Pediatrics (2022) has recently updated separate cut-off levels for total serum bilirubin

Phototherapy Exchange Uncomplicated fullterms (according to age)

Preterms/sick** fullterms (according to birth weight)

*Lower values of range indicate need to consider, while higher value indicate absolute need for intervention.

**For example, asphyxia, sepsis, hypoglycemia

in infants of different gestations 23 weeks onwards to consider exchange transfusion, with or without neurotoxicity risk factors.

Exchange transfusion is also used for other indications, e.g. severe septicaemia, severe anemia with CCF and severe polycythemia (Hct gt;65) as well as to remove toxins in some cases of inborn errors of metabolism, e.g. hyperglycinemia.

Choice of Blood

• Rh-HDN: Rh-ve blood with ABO group of baby, or O-ve blood cross-matched with mother and baby.

• ABO-HDN: 'O' Rh specific (with low anti-A or B-titers)

• Other indications: ABO and Rh group of baby.

Volume of exchange: Usually double of the baby's blood volume (80 ml/kg) needs to be exchanged for effective results, which replaces gt;85% of baby's blood and brings down bilirubin levels to ~ 50% of pre-exchange values. Route: Usually umbilical vein is cannulized for exchange transfusion due to its size, though peripheral veins may be used, if umbilical cannulation is not possible or umbilical sepsis is present. Normally, umbilical vein may be cannulized till 5-7 days.

Methodology: While detailed discussion is beyond the scope of this book, basic steps include:

• Obtain a free-flowing venous access and connect with a three-way cannula,

• Draw 10 cc of baby's blood for pre-exchange serum bilirubin and electrolyte levels.

• Withdraw 10-20 ml aliquot of baby's blood and then replace it with equal volume of donor's blood. Repeat the cycles till desired volume is exchanged.

• Monitor for complications. After each 50 ml exchange, 1 ml 10% calcium gluconate should be infused if ACD/ CPD blood is used, to prevent bleeding tendency.

• Send last baby's blood sample at the end of exchange transfusion, for post-exchange bilirubin/electrolyte estimation.

Complications: Exchange transfusion needs expert hands and common complications include:

• Metabolic: Hypocalcemia, hypoglycemia, acidosis

• Infections: Umb. sepsis, peritonitis, septicemia, NEC

• Traumatic: Cord bleeding, catheter injury

• Volume overload

• Hypothermia

• Late anemia, due to shorter life-span of infused RBCs that necessitates top-up transfusion.

III. Ancillary measures: Following measures, though of limited efficacy, are useful adjunct to phototherapy/ exchange transfusion in neonatal hyperbilirubinemia:

• IValbumin infusion (0.5 gm/kg) to bind free bilirubin, which is neurotoxic.

• IV immunoglobulins (0.5-1.0 gm/kg over 2-4 hours to reduce immune mediated hemolysis in Rh-HDN due to blocking the Fc receptors of reticuloendothelial cells which destroy antibody coated RBCs.

• Adequate breastfeeding to facilitate growth of gut flora.

• PO bilirubin-binders, e.g. agar, to prevent enterohepatic circulation.

• Management of BBB impairing conditions, e.g. hypoxia, acidosis and sepsis.

• Avoidance of drugs, known to displace bilirubin from albumin-binding sites, e.g. sulfa-drugs.

• Other modalities with equivocal results include use of phenobarbitone as microsomal enzyme inducer to enhance the conjugation of bilirubin, and synthetic metalloporphyrins to competitively inhibit heme oxygenase—a limiting enzyme for bilirubin synthesis. Use of oral bilirubin binders, e.g. agar, to prevent enterohepatic circulation is of limited value.

12.14.4