Jaundice is the most common condition that requires medical attention and hospital readmission in newborns.[89] The yellow coloration of the skin and sclera in newborns with jaundice is the result of accumulation of unconjugated bilirubin. In most infants, unconjugated hyperbilirubinemia reflects a normal transitional phenomenon. However, in some infants, serum bilirubin levels may rise excessively, which can be cause for concern because unconjugated bilirubin is neurotoxic and can cause death in newborns and lifelong neurologic sequelae in infants who survive (kernicterus).[89] For these reasons, the presence of neonatal jaundice frequently results in diagnostic evaluation.
Neonatal jaundice may have first been described in a Chinese textbook 1000 years ago. Medical theses, essays, and textbooks from the 18th and 19th centuries contain discussions about the causes and treatment of neonatal jaundice. Several of these texts also describe a lethal course in infants who probably had Rh isoimmunization. In 1875, Orth first described yellow staining of the brain, in a pattern later referred to by Schmorl as kernicterus.
Neonatal physiologic jaundice results from simultaneous occurrence of the following two phenomena[1] :
Bilirubin is produced in the reticuloendothelial system as the end product of heme catabolism and is formed through oxidation-reduction reactions. Approximately 75% of bilirubin is derived from hemoglobin, but degradation of myoglobin, cytochromes, and catalase also contributes. In the first oxidation step, biliverdin is formed from heme through the action of heme oxygenase, the rate-limiting step in the process, releasing iron and carbon monoxide. The iron is conserved for reuse, whereas carbon monoxide is excreted through the lungs and can be measured in the patient's breath to quantify bilirubin production.
Next, water-soluble biliverdin is reduced to bilirubin, which, because of the intramolecular hydrogen bonds, is almost insoluble in water in its most common isomeric form (bilirubin IXα Z,Z). Because of its hydrophobic nature, unconjugated bilirubin is transported in the plasma tightly bound to albumin. Binding to other proteins and erythrocytes also occurs, but the physiologic role is probably limited. Binding of bilirubin to albumin increases postnatally with age and is reduced in infants who are ill.
The presence of endogenous and exogenous binding competitors, such as certain drugs, also decreases the binding affinity of albumin for bilirubin. A minute fraction of unconjugated bilirubin in serum is not bound to albumin. This free bilirubin is able to cross lipid-containing membranes, including the blood-brain barrier, leading to neurotoxicity. In fetal life, free bilirubin crosses the placenta, possibly by a carrier-mediated process,[4] and excretion of bilirubin from the fetus occurs primarily through the maternal organism.
When it reaches the liver, bilirubin is transported into liver cells, where it binds to ligandin. Uptake of bilirubin into hepatocytes increases with increasing ligandin concentrations. Ligandin concentrations are low at birth but rapidly increase over the first few weeks of life. Ligandin concentrations may be increased by the administration of pharmacologic agents such as phenobarbital.
Bilirubin is bound to glucuronic acid (conjugated) in the hepatocyte endoplasmic reticulum in a reaction catalyzed by uridine diphosphoglucuronyltransferase (UDPGT). Monoconjugates are formed first and predominate in the newborn. Diconjugates appear to be formed at the cell membrane and may require the presence of the UDPGT tetramer.
Bilirubin conjugation is biologically critical because it transforms a water-insoluble bilirubin molecule into a water-soluble molecule. Water-solubility allows conjugated bilirubin to be excreted into bile. UDPGT activity is low at birth but increases to adult values by age 4-8 weeks. In addition, certain drugs (phenobarbital, dexamethasone, clofibrate) can be administered to increase UDPGT activity.
Infants who have Gilbert syndrome or who are compound heterozygotes for the Gilbert promoter and structural mutations of the UDPGT1A1 coding region are at an increased risk of significant hyperbilirubinemia. Interactions between the Gilbert genotype and hemolytic anemias such as glucose-6-phosphatase dehydrogenase (G-6-PD) deficiency, hereditary spherocytosis, or ABO hemolytic disease also appear to increase the risk of severe neonatal jaundice.
Further, the observation of jaundice in some infants with hypertrophic pyloric stenosis may also be related to a Gilbert-type variant. Genetic polymorphism for the organic anion transporter protein OATP-2 correlates with a 3-fold increased risk for developing marked neonatal jaundice. Combination of the OATP-2 gene polymorphism with a variant UDPGT1A1 gene further increases this risk to 22-fold.[5] Studies also suggest that polymorphisms in the gene for glutathione-S-transferase (ligandin) may contribute to higher levels of total serum bilirubin.
Thus, some interindividual variations in the course and severity of neonatal jaundice may be explained genetically.[6] As the impact of these genetic variants is more fully understood, development of a genetic test panel for risk of severe and/or prolonged neonatal jaundice may become feasible.[7]
Once excreted into bile and transferred to the intestines, bilirubin is eventually reduced to colorless tetrapyrroles by microbes in the colon. However, some deconjugation occurs in the proximal small intestine through the action of B-glucuronidases located in the brush border. This unconjugated bilirubin can be reabsorbed into the circulation, increasing the total plasma bilirubin pool. This cycle of uptake, conjugation, excretion, deconjugation, and reabsorption is termed 'enterohepatic circulation'. The process may be extensive in the neonate, partly because nutrient intake is limited in the first days of life, prolonging the intestinal transit time.
In mother-infant dyads who are experiencing difficulties with the establishment of breast feeding, inadequate fluid and nutrient intake often leads to significant postnatal weight loss in the infant. Such infants have an increased risk of developing jaundice through increased enterohepatic circulation, as described above. This phenomenon is often referred to as breastfeeding jaundice and is different from the breast milk jaundice described below.
Certain factors present in the breast milk of some mothers may also contribute to increased enterohepatic circulation of bilirubin (breast milk jaundice). β-glucuronidase may play a role by uncoupling bilirubin from its binding to glucuronic acid, thus making it available for reabsorption. Data suggest that the risk of breast milk jaundice is significantly increased in infants who have genetic polymorphisms in the coding sequences of the UDPGT1A1[8] or OATP2 genes. Although the mechanism that causes this phenomenon is not yet agreed on, evidence suggests that supplementation with certain breast milk substitutes may reduce the degree of breast milk jaundice (see Other therapies).
Neonatal jaundice, although a normal transitional phenomenon in most infants, can occasionally become more pronounced. Blood group incompatibilities (eg, Rh, ABO) may increase bilirubin production through increased hemolysis. Historically, Rh isoimmunization was an important cause of severe jaundice, often resulting in the development of kernicterus. Although this condition has become relatively rare in industrialized countries following the use of Rh prophylaxis in Rh-negative women, Rh isoimmunization remains common in low- and middle-income countries (LMICs).
Nonimmune hemolytic disorders (spherocytosis, G-6-PD deficiency) may also cause increased jaundice, and increased hemolysis appears to have been present in some of the infants reported to have developed kernicterus in the United States in the past 15-20 years. The possible interaction between such conditions and genetic variants of the Gilbert and UDPGT1A1 genes, as well as genetic variants of several other proteins and enzymes involved in bilirubin metabolism, is discussed above. More recently, 3 novel mutations in genes encoding either alpha or beta spectrin (SPTA1 or SPTB) were found in 3 unrelated neonates with nonimmune hemolytic jaundice.[87]
These discoveries also highlight the challenges involved in the common use of the terms physiologic jaundice and pathologic jaundice. Although physiologic jaundice is a helpful concept from a didactic perspective, applying it to an actual neonate with jaundice is more difficult.
Consider the following metaphor: Think of total serum bilirubin in neonatal jaundice as a mountain covered by a glacier. If a measurement of the height of the mountain is taken when standing on the summit, the amount of rock and the amount of ice that comprise this measurement is unclear. The same is true for many total serum bilirubin values obtained in neonatal jaundice. An underpinning of physiologic processes and pathological process (eg, Rhesus incompatibility) may clearly contribute to the measurement. However, how much of the measured total value comes from each of these components is unclear. Also, because genetic variants in bilirubin metabolism are only exceptionally pursued in the diagnostic work-up of infants with jaundice, their possible contribution to the measured total serum bilirubin is usually unknown.
Physiologic jaundice is caused by a combination of increased bilirubin production secondary to accelerated destruction of erythrocytes, decreased excretory capacity secondary to low levels of ligandin in hepatocytes, and low activity of the bilirubin-conjugating enzyme uridine diphosphoglucuronyltransferase (UDPGT).
Pathologic neonatal jaundice occurs when additional factors accompany the basic mechanisms described above. Examples include immune or nonimmune hemolytic anemia, polycythemia, and the presence of bruising or other extravasation of blood.
Decreased clearance of bilirubin may play a role in breast feeding jaundice, breast milk jaundice, and in several metabolic and endocrine disorders.
Risk factors include the following:
An estimated 50% of term and 80% of preterm infants develop jaundice, typically 2-4 days afer birth.[3] Neonatal hyperbilirubinemia is extremely common because almost every newborn develops an unconjugated serum bilirubin level of more than 30 µmol/L (1.8 mg/dL) during the first week of life. Incidence figures are difficult to compare because authors of different studies do not use the same definitions for significant neonatal hyperbilirubinemia or jaundice. In addition, identification of infants to be tested depends on visual recognition of jaundice by health care providers, which varies widely and depends both on observer attention and on infant characteristics such as race and gestational age.[12]
With the above caveats, epidemiologic studies provide a frame of reference for estimated incidence. In 1986, Maisels and Gifford reported 6.1% of infants with serum bilirubin levels of more than 220 µmol/L (12.9 mg/dL).[13] In a 2003 study in the United States, 4.3% of 47,801 infants had total serum bilirubin levels in a range in which phototherapy was recommended by the 1994 American Academy of Pediatrics (AAP) guidelines, and 2.9% had values in a range in which the 1994 AAP guidelines suggest considering phototherapy.[14] In some LMICs, the incidence of severe neonatal jaundice may be as much as 100 times higher than in higher-income countries.[15]
Incidence varies with ethnicity and geography. Incidence is higher in East Asians and American Indians and lower in Africans. Greeks living in Greece have a higher incidence than those of Greek descent living outside of Greece.
Incidence is higher in populations living at high altitudes. In 1984, Moore et al reported 32.7% of infants with serum bilirubin levels of more than 205 µmol/L (12 mg/dL) at 3100 m of altitude.[16]
A study from Turkey reported significant jaundice in 10.5% of term infants and in 25.3% of near-term infants.[17] Significant jaundice was defined according to gestational and postnatal age and leveled off at 14 mg/dL (240 µmol/L) at 4 days in preterm infants and 17 mg/dL (290 µmol/L) in the term infants. Severe neonatal jaundice is 100-fold more frequent in Nigeria than in industrialized countries.[15] In Denmark, 24 in 100.000 infants met exchange transfusion criteria, while 9 in 100.000 developed acute bilirubin encephalopathy.[18]
Studies seem to suggest that some of the ethnic variability in the incidence and severity of neonatal jaundice may be related to differences in the distribution of the genetic variants in bilirubin metabolism discussed above.[1, 5]
The incidence of neonatal jaundice is increased in infants of East Asian, American Indian, and Greek descent, although the latter appears to apply only to infants born in Greece and thus may be environmental rather than ethnic in origin. African infants are affected less often than non-African infants. For this reason, significant jaundice in an African infant merits a closer evaluation of possible causes, including G-6-PD deficiency. In 1985, Linn et al reported on a series in which 49% of East Asian, 20% of white, and 12% of black infants had serum bilirubin levels of more than 170 µmol/L (10 mg/dL).[19]
The possible impact of genetic polymorphisms on ethnic variation in incidence and severity should be recognized. Thus, in a study of Taiwanese infants, Huang et al reported that neonates who carry the 211 and 388 variants in the UGT1A1 and OATP2 genes and who are breastfed are at particularly high risk for severe hyperbilirubinemia.[1]
Risk of developing significant neonatal jaundice is higher in male infants. This does not appear to be related to bilirubin production rates, which are similar to those in female infants.
The risk of significant neonatal jaundice is inversely proportional to gestational age.
Prognosis is excellent if the patient receives treatment according to accepted guidelines.
Brain damage due to kernicterus remains a true risk, and the apparent increased incidence of kernicterus in recent years may be due to the misconception that jaundice in the healthy full-term infant is not dangerous and can be disregarded.
Kernicterus is a complication of neonatal jaundice.
The incidence of kernicterus in North America and Europe ranges from 0.4-2.7 cases per 100,000 births.[20] Death from physiologic neonatal jaundice per se should not occur. Death from kernicterus may occur, particularly in countries with less developed medical care systems. In one small study from rural Nigeria, 31% of infants with clinical jaundice tested had G-6-PD deficiency, and 36% of the infants with G-6-PD deficiency died with presumed kernicterus compared with only 3% of the infants with a normal G-6-PD screening test result.[21]
Please see the Medscape Drugs & Diseases article Kernicterus for more information.
Parents should be educated about neonatal jaundice and receive written information prior to discharge from the birth hospital. The parent information leaflet should preferably be available in several languages.
A novel 2-color icterometer (Bilistrip) appears to have the potential to facilitate early maternal detection of clinically significant jaundice and help them in decision making to seek medical treatment. In a study that trained mothers in a maternity hospital to use the icterometer on the blanched skin of their infant's nose to determine absence (light yellow) or presence (dark yellow) of significant jaundice, there was a 95.8% sensitivity and 95.8% negative predictive value for detecting infants requiring phototherapy.[82] Of the 2,492 mother-infant pairs in the study, 347 (13.9%) selected dark yellow; the 2-color icterometer missed only 1 of the 24 neonates who required phototherapy.
A smartphone application (BiliCam) has also been developed to assess neonatal jaundice.[81] It shows promise for effectively screening newborns in a diverse sample of newborns (age < 7 days), including black, Hispanic, and Asian infants. In a study comprising 530 newborns whose estimated bilirubin levels were calculated and compared with total serum bilirubin levels, the use of 2 decision rules resulted in the application providing accurate estimates of total serum bilirubin levels.[81]
Note the following:
Obtain the following information:
Ascertain the following information:
Obtain details of the following:
Neonatal jaundice first becomes visible in the face and forehead. Identification is aided by pressure on the skin, since blanching reveals the underlying color. Jaundice then gradually becomes visible on the trunk and extremities. This cephalocaudal progression is well described, even in 19th-century medical texts. Jaundice disappears in the opposite direction. The explanation for this phenomenon is not well understood, but both changes in bilirubin-albumin binding related to pH and differences in skin temperature and blood flow have been proposed.[22, 23] This phenomenon is claimed to be clinically useful because, independent of other factors, visible jaundice in the lower extremities strongly suggests the need to check the bilirubin level, either in the serum or noninvasively via transcutaneous bilirubinometry.
Recent work in the author’s group (Tølløfsrud et al, unpublished data) was not able to confirm this so-called cephalocaudal progression of jaundice. Thus, when dermal jaundice was measured noninvasively on the forehead, sternum, and symphysis, no cephalocaudal trend was evident.
In most infants, yellow color is the only finding on physical examination. More intense jaundice may be associated with drowsiness. Brainstem auditory-evoked potentials performed at this time may reveal prolongation of latencies, decreased amplitudes, or both.
Overt neurologic findings, such as changes in muscle tone, seizures, or altered cry characteristics, in a significantly jaundiced infant are danger signs and require immediate attention to prevent kernicterus. In the presence of such symptoms or signs, effective phototherapy should commence immediately without waiting for the laboratory test results (see Laboratory Studies). The potential need for exchange transfusion should not preclude the immediate initiation of phototherapy.[24, 25]
Hepatosplenomegaly, petechiae, and microcephaly may be associated with hemolytic anemia, sepsis, and congenital infections and should trigger a diagnostic evaluation directed towards these diagnoses. Neonatal jaundice may be exacerbated in these situations.
Bilirubin measurement may include the following:
Additional studies may be indicated in the following situations:
In addition to total serum bilirubin levels, other suggested studies may include the following, particularly if the rate of rise or the absolute bilirubin concentration is approaching the need for phototherapy:
Ultrasonography: Ultrasonography of the liver and bile ducts is warranted in infants with laboratory or clinical signs of cholestatic disease.
Radionuclide scanning: A radionuclide liver scan for uptake of hepatoiminodiacetic acid (HIDA) is indicated if extrahepatic biliary atresia is suspected. At the author's institution, patients are pretreated with phenobarbital 5 mg/kg/d for 3-4 days before performing the scan.
Auditory and visually evoked potentials are affected during ongoing significant jaundice; however, no criteria have been established that allow extrapolation from evoked potential findings to the risk of kernicterus. Data suggest that the probability of a bilateral "refer" on an automated auditory brainstem response (AABR) study increases with unbound bilirubin concentrations.[31] Because unbound bilirubin concentrations may be more closely correlated with bilirubin neurotoxicity, a "refer" finding may indicate an increased risk of bilirubin neurotoxicity. A "refer" AABR result obtained shortly after admission of an infant with significant jaundice seems to argue for immediate and aggressive treatment.
Brainstem auditory-evoked potentials should be obtained in the aftermath of severe neonatal jaundice to exclude sensorineural hearing loss. In physiologic jaundice, auditory-evoked potentials return to normal with the resolution of hyperbilirubinemia. However, in patients with significant neonatal jaundice or kernicterus, auditory-evoked potentials and functional hearing may remain abnormal.
The phonetic characteristics of the infant's cry are changed in significant neonatal jaundice; however, computerized analyses of these phonetic characteristics are not used in clinical practice.
Organs, including the brain, are yellow in any individual with significant jaundice; however, the yellow color does not always indicate CNS toxicity. This distinction was not always clearly understood in older descriptions of so-called "low-bilirubin kernicterus." At present, this has contributed to confusion and uncertainty regarding therapeutic guidelines and intervention levels.
See Kernicterus for a more detailed description.
Surgical care is not indicated in infants with physiologic neonatal jaundice. Surgical therapy is indicated in infants in whom jaundice is caused by bowel or external bile duct atresia.
For infants with physiologic neonatal jaundice, no consultation is required. Gastroenterologists and surgeons may be consulted regarding infants with jaundice resulting from hepatobiliary or bowel disease.
Phototherapy, intravenous immune globulin (IVIG), and exchange transfusion are the most widely used therapeutic modalities in infants with neonatal jaundice. Although medications that impact bilirubin metabolism have been used in studies, drugs are not ordinarily used in unconjugated neonatal hyperbilirubinemia.
Note that neonatal jaundice is a frequent comorbidity in sickle cell disease.[86] These infants may be more vulnerable to blue light phototherapy-induced oxidative stress (eg, increased lipid peroxidation and superoxide dismutase, slight change in activity of catalase and glutathione) and proinflammatory cytokine elevations (tumor necrosis factor alpha, interleukin [IL]-1 and 6).[86]
Phototherapy is the primary treatment in neonates with unconjugated hyperbilirubinemia.[3] This therapeutic principle was discovered rather serendipitously in England in the 1950s and is now arguably the most widespread therapy of any kind (excluding prophylactic treatments) used in newborns.
Phototherapy is effective because 3 reactions can occur when bilirubin is exposed to light, as follows:
The photoisomers of bilirubin are excreted in bile and, to some extent, in urine. The half-life of lumirubin in serum is much shorter than that in E isomers, and lumirubin is the primary pigment found in bile during phototherapy.
Bear in mind when initiating phototherapy that lowering of the total serum bilirubin concentration may be only part of the therapeutic benefit. Because photoisomers, by virtue of their water-soluble nature, should not be able to cross the blood-brain barrier, phototherapy may reduce the risk of bilirubin-induced neurotoxicity as soon as the lights are turned on. At any given total serum bilirubin concentration, the presence of 20-25% of photoisomers means that only 75-80% of the total bilirubin may be present in a form that can enter the brain. Please note that although theoretically coherent, no experimental data support this speculation.
Phototherapy can be administered in a number of ways. To understand the benefits and limitations of the various approaches, some basic principles regarding wavelength and types of light are discussed below with comments and suggestions regarding each system.
First, wavelength must be considered. Bilirubin absorbs light primarily around 450-460 nm. However, the ability of light to penetrate skin is also important; longer wavelengths penetrate better. Thus, lamps with output predominantly in the blue region of the spectrum (460-490 nm) are probably most effective. In practice, light is used in the white, blue, turquoise, and green wavelengths.
Second, previously a dose-response relationship was thought to exist between the amount of irradiation and reduction in serum bilirubin up to an irradiation level of 30-40 µW/cm2/nm. Many older phototherapy units deliver much less energy, some at or near the minimally effective level, which appears to be approximately 6 µW/cm2/nm. On the other hand, newer phototherapy units, when properly configured and with the use of reflecting blankets and curtains may deliver light energy above 40 µW/cm2/nm. Recent data do not confirm that there really is a saturation level.[33] Thus, the relationship between irradiance and the 24-hour decrement in total serum bilirubin was linear up to 55 μW/cm2, and with no evidence of a saturation point.
Third, the energy delivered to the infant's skin decreases with increasing distance between the infant and the light source. This distance should not be greater than 50 cm (20 in) and can be less (down to 10 cm) provided the infant's temperature is monitored.
Fourth, the efficiency of phototherapy depends on the amount of bilirubin that is irradiated. Irradiating a large skin surface area is more efficient than irradiating a small area, and the efficiency of phototherapy increases with serum bilirubin concentration.
Fifth, the nature and character of the light source may affect energy delivery. Irradiation levels using quartz halide spotlights are maximal at the center of the circle of light and decrease sharply towards the perimeter of the circle. Large infants and infants who can move away from the circle's center may receive less efficient phototherapy.
Although green light theoretically penetrates the skin better, it has not been shown unequivocally to be more efficient in clinical use than blue or white light. Because green light makes babies look sick and is unpleasant to work in, green light has not gained widespread acceptance.
Blue fluorescent tubes are widely used for phototherapy.[88] Narrow-spectrum blue lamps (special blue) appear to work best, while ordinary blue fluorescent lamps are probably equivalent to standard white daylight lamps. Blue lights may cause discomfort in hospital staff members, which can be ameliorated by mixing blue and white tubes in the phototherapy unit.
White (daylight) fluorescent tubes are less efficient than special blue lamps; however, decreasing the distance between infants and lamps can compensate for the lower efficiency. Use of reflecting materials also helps. Thus, in LMICs where the cost of special blue lamps may be prohibitive, efficient phototherapy is accomplished with white lamps.
White quartz lamps are an integral part of some radiant warmers and incubators. They have a significant blue component in the light spectrum. When used as spotlights, the energy field is strongly focused towards the center, with significantly less energy delivered at the perimeter, as discussed above.
Quartz lamps are also used in single or double banks of 3-4 bulbs attached to the overhead heat source of some radiant warmers. The energy field delivered by these is much more homogeneous than that of spotlights, and the energy output is reasonably high. However, because the lamps are fixed to the overhead heater unit, the ability to increase energy delivery by moving lights closer to infants is limited.
Fiberoptic lights are also used in phototherapy units. These units deliver high energy levels, but because spectral power (ie, irradiance multiplied by the size of the irradiated area) is related to the size of the lighted field, the smaller "pads" are less efficient than larger wrap-around blankets. Drawbacks of fiberoptic phototherapy units may include noise from the fan in the light source and a decrease of delivered energy with aging and/or breakage of the optic fibers. Some new fiberoptic units now incorporate photodiodes as a light source. Advantages of fiberoptic phototherapy include the following:
Light-emitting diode (LED) lights are found in most newer phototherapy units. Advantages include low power consumption, low heat production, and a much longer life span of the light-emitting units (20,000 hours) compared with older light sources. Blue LED lights have a narrow spectral band of high-intensity light that overlaps the absorption spectrum of bilirubin. Trials comparing LED phototherapy to other light sources were recently reviewed by the Cochrane Collaboration and by Tridente and DeLuca. The authors of these reviews conclude that the efficacy of LED lights in reducing total serum bilirubin levels is comparable to that of conventional light sources (fluorescent or halogen lamps).[34, 35] Formation of bilirubin photoisomers also appears comparable between LEDs and blue fluorescent lamps.[32]
"Double" and "triple" phototherapy, which implies the concurrent use of 2 or 3 phototherapy units to treat the same patient, has often been used in the treatment of infants with very high levels of serum bilirubin. The studies that appeared to show a benefit with this approach were performed with old, relatively low-yield phototherapy units. Newer phototherapy units provide much higher levels of irradiance. Whether double or triple phototherapy also confers a benefit with the newer units, has not been tested in systematic trials. However, because recent studies appear to rule out the existence of a saturation point (see discussion above), the utility of double or triple phototherapy in extreme jaundice should not be discounted.[32]
The purpose of treating neonatal jaundice is to avoid neurotoxicity. Thus, indications for treatment have been based on clinical studies of infants who developed kernicterus. Historical data, much of which was derived from infants with hemolytic jaundice, appeared to suggest that total serum bilirubin levels greater than 350 µmol/L (20 mg/dL) were associated with increased risk of neurotoxicity, at least in full-term infants.
As treatment of premature infants became more widespread and increasingly successful during the last half of the 20th century, autopsy findings and follow-up data suggested that immature infants were at risk of bilirubin encephalopathy at lower total serum bilirubin levels than mature infants. Treatment was initiated at lower levels for these infants.
Until the 1940s, a truly effective treatment was not available. At that time, exchange transfusion was shown to be feasible and was subsequently used in the treatment of Rh-immunized infants with severe anemia, hyperbilirubinemia, or hydrops. However, exchange transfusion is not without risk for the infant, and only with the discovery of phototherapy did neonatal jaundice start to become an indication for treatment on a wider scale. Once phototherapy was shown to be an apparently innocuous treatment, lights were turned on at lower serum bilirubin values than those that had triggered exchange transfusion.
Exchange transfusion became the second-line treatment when phototherapy failed to control serum bilirubin levels. However, data have shown that treatment with IVIG in infants with Rh or ABO isoimmunization can significantly reduce the need for exchange transfusions.[36, 37] At the author's institution, a tertiary center where exchange transfusions used to be frequent, currently only 0-2 such procedures per year are performed, and IVIG has replaced exchange transfusion as the second-line treatment in infants with isoimmune jaundice.[38] In a recent 1-year prospective national survey of NICU phototherapy practices in Norway, Mreihil and collaborators found that only 6 exchange transfusions had been performed in a birth population of 60.000 infants (Mreihil K et al, preliminary data).
Clearly, the scientific data on which current therapeutic guidelines are based have very significant shortcomings. Unfortunately, because the endpoint of bilirubin neurotoxicity is permanent brain damage, a randomized study to reassess the guidelines is ethically unthinkable.
In most neonatal wards, total serum bilirubin levels are used as the primary measure of risk for bilirubin encephalopathy. Numerous people would prefer to add a test for serum albumin at higher bilirubin levels because bilirubin entry into the brain, a sine qua non for bilirubin encephalopathy, increases when the bilirubin-albumin ratio exceeds unity. Tests for bilirubin-albumin binding or unbound bilirubin levels are used by some but have failed to gain widespread acceptance. New analytical tools for measurement of unbound bilirubin have greatly simplified the process, but the effect on clinical practice remains to be seen.
Numerous guidelines for the management of neonatal jaundice have been published, and even more appear to be in local use without submission for critical review. In a survey published in 1996, the author analyzed clinical practices in this field based on responses from 108 neonatal intensive care units (NICUs) worldwide.[39] The survey revealed a significant disparity in guidelines.
The image below shows a box-and-whisker plot of the range of serum bilirubin values that trigger phototherapy and exchange transfusion, respectively, in these NICUs. Evidently, an infant might receive an exchange transfusion in one NICU for a serum bilirubin level that would not trigger phototherapy in many other NICUs. This disparity illustrates how difficult it has been to translate clinical data into sensible treatment guidelines.
View Image | The graph represents indications for phototherapy and exchange transfusion in infants (with a birthweight of 3500 g) in 108 neonatal ICUs. The left pa.... |
In 2004, the AAP published new guidelines for the management of hyperbilirubinemia in healthy full-term newborns.[40] These guidelines have been plotted on the image above.
The 2004 AAP guidelines represent a significant change from the 1994 guidelines.[40] Thus, the emphasis on preventive action and risk evaluation is much stronger. An algorithm aids in the assessment of risk and the decision about further management and follow-up (see the image below). The committee that wrote the guidelines has carefully assessed the strength of the scientific evidence on which the guidelines are based.
View Image | Algorithm for the management of jaundice in the newborn nursery. |
Practitioners in North America are advised to follow the 2004 AAP guidelines. Although the 2004 AAP guidelines do not provide guidance for treatment of jaundice in the smaller and more premature/immature infants, a group of US experts recently published their suggestions for management of jaundice in preterm infants younger than 35 weeks' gestation.[41]
Clinicians in different ethnic or geographic regions should consider tailoring these guidelines as pertinent to their own populations and must consider factors that are unique to their medical practice settings. Such factors may include racial characteristics, prevalence of congenital hemolytic disorders, prevalence of genetic variants, and environmental concerns. Such adaptation of guidelines should also take into consideration how healthcare delivery systems are organized, as this is likely affect both in-hospital delivery of care as well as follow-up. At present, the wisest course of action may be to apply local guidelines, assuming that these have been successful in the prevention of kernicterus..
With this background and the clear understanding that this is meant only as an example, the image below shows the chart currently in use in all pediatric departments in Norway. These guidelines are the result of a 2006 consensus in the Neonatal Subgroup of the Norwegian Pediatric Society. The similarities between the Norwegian chart and the 2004 AAP guidelines are apparent.
View Image | Guidelines for management of neonatal jaundice currently in use in all pediatric departments in Norway. The guidelines were based on previously used c.... |
The Norwegian chart suggests intervention limits for premature/immature infants. For infants of less than 1000 gram birthweight, these guidelines propose starting phototherapy at 100 µmol/L (6 mg/dL) at age 24 hours, increasing gradually to 150 µmol/L (8.8 mg/dL) at age 4 days, and remaining steady thereafter at that level. This compares with a range of 85 µmol/L (5 mg/dL) to 171 µmol/L (10 mg/dL) used in a Neonatal Research Network (NRN) phototherapy trial in infants of less than 1000 gram birthweight. The intervention level depended on postnatal age and whether the infant was allocated to conservative or aggressive phototherapy.[42]
In a post hoc analysis of the NRN data, which compared infants who had not received any phototherapy with those who had received such treatment, the subgroup of infants with birthweights of 501-750 grams who had not received any phototherapy had a significantly higher rate of mental developmental index of less than 50.[43] However, it should be noted that in the original trial analysis, mortality in the aggressive phototherapy group at 501- to 750-g birthweight was 5 percentage points higher than in the conservative group, which, although not significant with the statistical approach chosen for analysis, appeared to offset the possible developmental gain in survivors.[42] Recently these data were reanalyzed using Bayesian statistics[44] and showed that aggressive phototherapy significantly increased the risk of death in the sickest (being on mechanical ventilation at 24 h) and smallest infants (≤750 g birthweight), while at the same time reducing impairment/severe impairment.
Key points in the practical execution of phototherapy include maximizing energy delivery and the available surface area. Also consider the following:
Generally, phototherapy is very safe and may have no serious long-term effects in neonates; however, the following adverse effects and complications have been noted:
In relatively recent years, IVIG has been used for numerous immunologically mediated conditions. In the presence of Rh, ABO, or other blood group incompatibilities that cause significant neonatal jaundice, IVIG has been shown to significantly reduce the need for exchange transfusions. However, it must be recognized that some studies have failed to show efficacy. The reasons for this discrepancy have not been explained, but it should be noted that in the studies that failed to show significant effects, IVIG was used more or less prophylactically for all apparently immunized infants, whereas in the studies that reported benefits IVIG was used exclusively as a rescue therapy in infants headed for exchange transfusion. Also, one can speculate whether differences in the origin and characteristics of the IVIG preparation might play a role. If one particular IVIG preparation appears not to work, it may be worthwhile to try IVIG from a different source/manufacturer.
The 2004 AAP guidelines suggest a dose range for IVIG of 500-1000 mg/kg.[40]
The author routinely uses 500 mg/kg infused intravenously over a period of 2 hours for Rh or ABO incompatibility when the total serum bilirubin levels approach or surpass the exchange transfusions limits. The author has, on occasion, repeated the dose 2-3 times. In most cases, when this is combined with intensive phototherapy, avoiding exchange transfusion is possible. In the authors' institution, with about 750 NICU admissions per year, the use of exchange transfusions has decreased to 0-2 per year following the implementation of IVIG therapy for Rh and ABO isoimmunization.[38] The author does not use IVIG in the presence of hydrops. Anecdotally, IVIG appears less likely to be successful when the infant is anemic (Hb < 10 g/dL).
Exchange transfusion is indicated for avoiding bilirubin neurotoxicity when other therapeutic modalities have failed or are not sufficient. In addition, the procedure may be indicated in infants with erythroblastosis who present with severe anemia, hydrops, or both, even in the absence of high serum bilirubin levels.
Exchange transfusion was once a common procedure. A significant proportion was performed in infants with Rh isoimmunization. Immunotherapy in Rh-negative women at risk for sensitization has significantly reduced the incidence of severe Rh erythroblastosis. Therefore, the number of infants requiring exchange transfusion is now much smaller, and even large NICUs may perform only a few procedures per year. As mentioned previously, the incidence of infants requiring exchange transfusion in Norway was in a prospective survey shown to be only 0.01% (Mrehil K et al, preliminary data). ABO incompatibility has become the most frequent cause of hemolytic disease in industrialized countries.
Early exchange transfusion has usually been performed because of anemia (cord hemoglobin < 11 g/dL), elevated cord bilirubin level (>70 µmol/L or 4.5 mg/dL), or both. A rapid rate of increase in the serum bilirubin level (>15-20 µmol/L /h or 1 mg/dL/h) was an indication for exchange transfusion, as was a more moderate rate of increase (>8-10 µmol/L/h or 0.5 mg/dL/h) in the presence of moderate anemia (11-13 g/dL).
The serum bilirubin level that triggered an exchange transfusion in infants with hemolytic jaundice was 350 µmol/L (20 mg/dL) or a rate of increase that predicted this level or higher. Strict adherence to the level of 20 mg/dL has been jocularly referred to as vigintiphobia (fear of 20).
Currently, most experts encourage an individualized approach, recognizing that exchange transfusion is not a risk-free procedure, that effective phototherapy converts 15-25% of bilirubin to nontoxic isomers, and that transfusion of a small volume of packed red cells may correct anemia. Administration of IVIG (500 mg/kg) has been shown to reduce red cell destruction and to limit the rate of increase of serum bilirubin levels in infants with Rh and ABO isoimmunization (see above).
Current AAP guidelines distinguish between 3 risk categories: low, intermediate, and high.[40] These correspond to 3 levels of suggested intervention, which increase from birth and plateau at age 4 days. Naturally, intervention levels associated with exchange transfusion are higher than those for phototherapy. Intensive phototherapy is strongly recommended in preparation for an exchange transfusion. In fact, intensive phototherapy should be performed on an emergency basis in any infant admitted for pronounced jaundice; do not await laboratory test results in these cases. Phototherapy has minimal side effects in this scenario, whereas the waiting period for laboratory test results and blood for exchange can take hours and could constitute the difference between intact survival and survival with kernicterus. If phototherapy does not significantly lower serum bilirubin levels, exchange transfusion should be performed.
Many believe that hemolytic jaundice represents a greater risk for neurotoxicity than nonhemolytic jaundice, although the reasons for this belief are not intuitively obvious, assuming that total serum bilirubin levels are equal. In animal studies, bilirubin entry into or clearance from the brain was not affected by the presence of hemolytic anemia.
The technique of exchange transfusion, including adverse effects and complications, is discussed extensively elsewhere. For more information, please consult Hemolytic Disease of Newborn.
Numerous cases have been reported in which infants have been readmitted to hospitals with extreme jaundice. In some cases, significant delays have occurred between the time the infant was first seen by medical personnel and the actual commencement of effective therapy.[47]
Any infant who returns to the hospital with significant jaundice within the first 1-2 weeks of birth should be immediately triaged with measurement of transcutaneous bilirubin. High values should result in immediate initiation of treatment. If such a measuring device is not available, or if the infant presents with any kind of neurological symptoms, the infant should be put in maximally efficient phototherapy as an emergency procedure, preferably by fast-tracking the infant to a NICU. Waiting for laboratory results is not necessary before instituting such therapy because no valid contraindications to phototherapy are possible in this scenario. Plans for an exchange transfusion do not constitute an argument for delaying or not performing phototherapy. Immediate benefit may be obtained within minutes, as soon as conversion of bilirubin into water-soluble photoisomers is measurable (see discussion above).
The need for intravenous hydration in such infants has been discussed. In the absence of clinical signs of dehydration, no evidence suggests that overhydration is helpful. If the infant is dehydrated, hydration should be given as clinically indicated. However, if the infant is able to tolerate oral feeding, oral hydration with a breast milk substitute is likely to be superior to intravenous hydration because it reduces enterohepatic circulation of bilirubin and helps "wash" bilirubin out of the bowel.
Every hospital in which babies are delivered, or which has an emergency department in which infants may be seen, should develop a protocol and triage algorithm for rapid evaluation and management of jaundiced infants. The objective of such a protocol should be rapid recognition of risk severity and reduction in the time to initiate appropriate treatment.
Infants admitted with signs of intermediate to advanced acute bilirubin encephalopathy (ABE) are in urgent need of treatment because reversibility may be possible, even in such cases. The term "crash-cart approach" has been used as a recommendation in such cases. The author, together with other European colleagues, has published a series that included 6 patients with signs of ABE who were urgently managed and appear to have escaped neurologic sequelae.[48]
In a review of the Kernicterus Registry, full recovery was noted in 8 of 11 cases treated with a crash-cart approach, which included effective phototherapy plus exchange transfusion; full recovery was not noted in cases in which delays had occurred.[47] In the Kernicterus Registry, reversal was not observed in cases treated with only phototherapy; the authors strongly recommend that exchange transfusion be performed in such cases.[47] In the European study, reversal was also seen in 2 patients who did not receive exchange transfusion.[48] In one of these cases, IVIG was used in lieu of exchange transfusion; in the other case, intensive phototherapy and intravenous albumin were used.
In infants with breast milk jaundice, interruption of breastfeeding for 24-48 hours and feeding with breast milk substitutes often helps to reduce the bilirubin level. Evidence suggests that the simple expedient of supplementing feeds of breast milk with 5 mL of a breast milk substitute reduces the level and duration of jaundice in breast milk–fed infants. Because this latter intervention causes less interference with the establishment of the breastfeeding dyad, the author prefers to use this approach rather than complete interruption of breast feeding in most cases.
Oral bilirubin oxidase can reduce serum bilirubin levels, presumably by reducing enterohepatic circulation; however, its use has not gained wide popularity. The same may be said for agar or charcoal feeds, which act by binding bilirubin in the gut. Bilirubin oxidase is not available as a drug, and for this reason, its use outside an approved research protocol probably is proscribed in many countries.
Prophylactic treatment of Rh-negative women with Rh immunoglobulin has significantly decreased the incidence and severity of Rh-hemolytic disease.
Breastfeeding concerns associated with neonatal jaundice are as follows:
In the era of early discharge, newborns released within the first 48 hours of life need to be reassessed for jaundice within 1-2 days. The use of the hour-specific bilirubin nomogram may assist in selecting infants with a high likelihood of developing significant hyperbilirubinemia. The 2004 AAP guidelines emphasize the importance of universal systematic assessment for the risk of severe hyperbilirubinemia.[40] Guidelines from the European Society for Pediatric Research reiterate the same principles.[24]
Neonatal jaundice is one of the most common reasons why neonates are brought to an emergency department after discharge from the birth hospital.[49]
Near-term infants are at higher risk than term infants of developing significant jaundice and merit closer surveillance.[50]
The question of universal bilirubin screening has received attention and is the subject of debate. Some data suggest that predischarge bilirubin screening reduces the number of infants with severe jaundice, as well as the rate of hospital readmissions.[51, 52] Others have found that home nurse visiting was cost-effective and prevented readmissions for jaundice and dehydration.[53] However, the cost-effectiveness of preventing kernicterus by universal screening has been questioned.[54]
Nevertheless, in an update to the 2004 AAP jaundice guidelines Maisels et al give a clear recommendation in favor of predischarge bilirubin screening, either by transcutaneous measurement or by serum analysis.[55]
These authors also recommend a more structured approach to management and follow-up according to the predischarge total serum bilirubin and transcutaneous bilirubin (TcB) levels, gestational age (see the Gestational Age from Estimated Date of Delivery calculator), and other risk factors for hyperbilirubinemia. These risk factors include the following:[55]
Telephone consultations are not recommended because parental reports cannot be appropriately gauged. Recently, numerous infants have developed kernicterus, resulting, at least in part, from inadequate communication between practitioners or their representatives and parents.
The availability of new devices for transcutaneous measurement of bilirubin levels should facilitate follow-up evaluations of infants discharged before 48 hours of life.
Home phototherapy is used in an effort to limit the high cost of applying such therapy in hospitals. Note the following:
Infants who have been treated for hemolytic jaundice require follow-up observation for several weeks because hemoglobin levels may fall lower than seen in physiologic anemia. Erythrocyte transfusions may be required if infants develop symptomatic anemia.
Prevention of severe neonatal jaundice is best achieved through attention to the risk status of the infant prior to discharge from the birth hospital, through parent education, and through careful planning of postdischarge follow-up.[24, 40]
A predischarge bilirubin measurement, obtained by transcutaneous or serum measurement and plotted into an hour-specific nomogram, has been shown to be a useful tool in distinguishing infants with a low risk of subsequently developing high bilirubin values.
Clinical risk factors include gestational age of less than 38 weeks, the use of oxytocin or vacuum during delivery, exclusive breast feeding, an older sibling with neonatal jaundice that required phototherapy, a rise of ≥ 6 mg/dL/d (≥ 100 μ mol/L/d) in total serum bilirubin levels, and hematomas or extensive bruising. Birth weight is also associated with risk of developing significant jaundice; the higher the birthweight in term infants, the higher the risk.
Medications are not usually administered in infants with physiologic neonatal jaundice. However, in certain instances, phenobarbital, an inducer of hepatic bilirubin metabolism, has been used to enhance bilirubin metabolism. Several studies have shown that phenobarbital is effective in reducing mean serum bilirubin values during the first week of life. Phenobarbital may be administered prenatally in the mother or postnatally in the infant.
In populations in which the incidence of neonatal jaundice or kernicterus is high, this type of pharmacologic treatment may warrant consideration. However, concerns surround the long-term effects of phenobarbital on these children. Therefore, this treatment is probably not justified in populations with a low incidence of severe neonatal jaundice. Other drugs can induce bilirubin metabolism, but lack of adequate safety data prevents their use outside research protocols.
Intravenous immunoglobulin (IVIG) at 500 mg/kg has been shown to significantly reduce the need for exchange transfusions in infants with isoimmune hemolytic disease.[38] The mechanism is unknown but may be related to the way the immune system handles red cells that have been coated by antibodies. Published experience is still somewhat limited, but administration of immunoglobulin does not appear to be likely associated with greater risks for the infant than an exchange transfusion. Published data regarding efficacy are varied, perhaps having to do with different study sets-up, as studies that show effects of IVIG as far as reducing exchange transfusion have used this drug in a rescue modailty only. One may also speculate that the specific origin and characteristics of the IVIG preparation could play a role. Although speculative, lack of efficacy of a specific IVIG product may warrant trial of one from a different manufacturer or batch.
A new therapy currently under development consists of inhibition of bilirubin production through blockage of heme oxygenase. This can be achieved through the use of metal mesoporphyrins and protoporphyrins. Apparently, heme can be directly excreted through the bile; thus, inhibition of heme oxygenase does not result in accumulation of unprocessed heme. This approach may virtually eliminate neonatal jaundice as a clinical problem. However, before the treatment can be applied on a wide scale, important questions regarding the long-term safety of the drugs must be answered. Also, in light of data suggesting that bilirubin may play an important role as a free radical quencher, a more complete understanding of this putative role for bilirubin is required before wholesale inhibition of its production is contemplated.
Supplementation of probiotics appears to show promise for newborns with pathologic neonatal jaundice. A systematic review and meta-analysis of 13 randomized controlled trials involving 1,067 neonates with jaundice who received probiotics showed a reduction in total serum bilirubin levels after 3, 5, and 7 days, as well as a decrease in the time of jaundice fading, the duration of phototherapy, and length of hospitalization relative to neonates in the control group.[83] The investigators did not find any reports of serious adverse events.
Zinc sulfate supplementation is a controversial potential approach for treating neonatal jaundice. A systematic review and meta-analysis comprising data from 645 neonates over 5 randomized controlled trials did not show any significant reductions in levels of total serum bilirubin on days 3 and 7, nor reductions in the incidence of bilirubinemia and phototherapy requirements, but zinc supplementation did result in a significantly shorter duration of phototherapy.[84]
Infants who have been treated for neonatal jaundice can be discharged when they are feeding adequately and have had 2 successive serum bilirubin levels demonstrating a trend towards lower values.
If the hospital does not routinely screen newborns for auditory function, ordering such tests prior to discharge is advisable in infants who have had severe jaundice.
The 2004 AAP guideline recommends a systematic risk assessment for hyperbilirubinemia risk in all infants before discharge.[40] Parents should be provided with verbal and written information about jaundice.
Infants in need of exchange transfusion born at or admitted to facilities not capable of performing this procedure should be transferred to the nearest facility with such capability. In addition to complete records, the infant should be accompanied by a sample of maternal blood because this is needed by the blood bank to match blood.
However, in determining the best use of time before transfer, as well as the timing of the transfer, the following factors should be considered:
Even if the receiving hospital determines that an exchange transfusion should be performed, continuing optimal phototherapy until the actual exchange procedure can commence is important. If fiberoptic phototherapy is available, the infant may be left on a fiberoptic mattress while the exchange is carried out. Oral hydration with a breast milk substitute may aid the clearance of bilirubin from the gut, thus inhibiting enterohepatic circulation of bilirubin, and should be given unless clearly contraindicated by the clinical state of the infant. Although none of these suggestions have been tested in randomized controlled trials, case reports, bilirubin photobiology, and expert opinion suggest that they may be beneficial and, at the very least, are unlikely to be harmful.
The graph represents indications for phototherapy and exchange transfusion in infants (with a birthweight of 3500 g) in 108 neonatal ICUs. The left panel shows the range of indications for phototherapy, whereas the right panel shows the indications for exchange transfusion. Numbers on the vertical axes are serum bilirubin concentrations in mg/dL (lateral) and mmol/L (middle). In the left panel, the solid line refers to the current recommendation of the American Academy of Pediatrics (AAP) for low-risk infants, the line consisting of long dashes (- - - - -) represents the level at which the AAP recommends phototherapy for infants at intermediate risk, and the line with short dashes (-----) represents the suggested intervention level for infants at high risk. In the right panel, the dotted line (......) represents the AAP suggested intervention level for exchange transfusion in infants considered at low risk, the line consisting of dash-dot-dash (-.-.-.-.) represents the suggested intervention level for exchange transfusion in infants at intermediate risk, and the line consisting of dash-dot-dot-dash (-..-..-..-) represents the suggested intervention level for infants at high risk. Intensive phototherapy is always recommended while preparations for exchange transfusion are in progress. The box-and-whisker plots show the following values: lower error bar = 10th percentile; lower box margin = 25th percentile; line transecting box = median; upper box margin = 75th percentile; upper error bar = 90th percentile; and lower and upper diamonds = 5th and 95th percentiles, respectively.
Guidelines for management of neonatal jaundice currently in use in all pediatric departments in Norway. The guidelines were based on previously used charts and were created through a consensus process in the Neonatal Subgroup of the Norwegian Pediatric Society. These guidelines were adopted as national at the fall meeting of the Norwegian Pediatric Society. The reverse side of the chart contains explanatory notes to help the user implement the guidelines. A separate information leaflet for parents was also created.
The graph represents indications for phototherapy and exchange transfusion in infants (with a birthweight of 3500 g) in 108 neonatal ICUs. The left panel shows the range of indications for phototherapy, whereas the right panel shows the indications for exchange transfusion. Numbers on the vertical axes are serum bilirubin concentrations in mg/dL (lateral) and mmol/L (middle). In the left panel, the solid line refers to the current recommendation of the American Academy of Pediatrics (AAP) for low-risk infants, the line consisting of long dashes (- - - - -) represents the level at which the AAP recommends phototherapy for infants at intermediate risk, and the line with short dashes (-----) represents the suggested intervention level for infants at high risk. In the right panel, the dotted line (......) represents the AAP suggested intervention level for exchange transfusion in infants considered at low risk, the line consisting of dash-dot-dash (-.-.-.-.) represents the suggested intervention level for exchange transfusion in infants at intermediate risk, and the line consisting of dash-dot-dot-dash (-..-..-..-) represents the suggested intervention level for infants at high risk. Intensive phototherapy is always recommended while preparations for exchange transfusion are in progress. The box-and-whisker plots show the following values: lower error bar = 10th percentile; lower box margin = 25th percentile; line transecting box = median; upper box margin = 75th percentile; upper error bar = 90th percentile; and lower and upper diamonds = 5th and 95th percentiles, respectively.
Guidelines for management of neonatal jaundice currently in use in all pediatric departments in Norway. The guidelines were based on previously used charts and were created through a consensus process in the Neonatal Subgroup of the Norwegian Pediatric Society. These guidelines were adopted as national at the fall meeting of the Norwegian Pediatric Society. The reverse side of the chart contains explanatory notes to help the user implement the guidelines. A separate information leaflet for parents was also created.