Serum alpha-fetoprotein levels in extrahepatic biliary atresia, idiopathic neonatal hepatitis and alpha-1-antitrypsin deficiency (PiZ).

Serum alpha-fetoprotein levels were measured using a sensitive radioimmunoassay in 77 infants presenting with persistent conjugated hyperbilirubinaemia. A breed range of alpha-fetoprotein concentrations occurred in both the 23 infants with extrahepatic biliary atresia and the 35 with idiopathic neonatal hepatitis but the 13 with alpha-1-antitrypsin deficiency had uniformly low levels. High alpha-fetoprotein concentrations (above 10 000 mug/1) favoured the diagnosis of neonatal hepatitis especially in the first ten weeks of life, but the overlap between neonatal hepatitis and extrahepatic biliary atresia was large and alpha-fetoprotein determination cannot be recommended as a reliable method for distinguishing the two conditions. Serial alpha-fetoprotein values showed no consistent relationship with standard liver function tests and gave no guide to prognosis. There was an association between alpha-fetoprotein production and needle biopsy evidence of hepatic giant cell transformation. The uniformly low alpha-fetoprotein levels in alpha-1-antitrypsin deficient infants with neonatal hepatitis is a new observation and possible mechanisms for disordered glycoprotein release are discussed.     

Lack of correlation between infection with reovirus 3 and extrahepatic biliary atresia or neonatal hepatitis

Infection with reovirus 3 (Reo-3) has been suggested as the cause of extrahepatic biliary atresia and idiopathic neonatal hepatitis, but confirmation has been lacking. Therefore we have searched for a specific anti-Reo-3 antibody response in the sera of patients with biliary atresia or neonatal hepatitis and for Reo-3 antigens in their hepatobiliary tissues. Sera from 23 infants with extrahepatic biliary atresia, 12 with neonatal hepatitis, 30 age-matched control patients with other liver diseases, and 55 control patients without liver disease were tested by an enzyme-linked immunosorbent assay for total (IgA, IgG, and IgM) anti-Reo-3 antibodies; sera of infants younger than 6 months of age were tested also for IgM anti-Reo-3 antibodies alone. There was no difference between either total or IgM anti-Reo-3 antibody levels in infants with extrahepatic biliary atresia or neonatal hepatitis and levels in control infants. Reo-3 antigens were not detected in the hepatobiliary tissues of 19 infants (18 with biliary atresia, one with neonatal hepatitis) by an immunoperoxidase method that readily demonstrated Reo-3 in control infected HEp-G2 cells. Our data do not support a relationship between neonatal liver diseases and infection with Reo-3.     

Alpha1-fetoprotein in neonatal hepatobiliary disease.

It has been suggested that the quantitative estimation of serum alpha-1-fetoprotein may help in distinguishing the neonatal hepatitis syndrome from biliary atresia. We measured the serum AFP concentration in 52 neonates and infants with various hepatobiliary disorders, including neonatal hepatitis syndrome (group I), biliary atresia (group II), and other hepatopathies such as choledochal cyst (group III). The mean serum AFP concentration in patients with neonatal hepatitis was significantly greater than the mean concentration in the other two groups. There was no significant difference between the mean serum AFP concentrations in patients with biliary atresia and in group III patients. Patient age was noted to be an important factor: Serum AFP levels greater than 35 microgram/ml in infants one to four months of age suggpst the diagnosis of neonatal hepatitis syndrome. Serum AFP levels below 10 microgram/ml in infants less than four months of age suggest the diagnosis of biliary atresia or hepatopathies other than neonatal hepatitis. However, the variable and significant overlapping of serum AFP values between 10 and 35 microgram/ml limit the diagnostic value of this test.     

Extrahepatic biliary atresia versus neonatal hepatitis. Review of 137 prospectively investigated infants.

In a prospective regional survey of neonatal hepatitis syndrome 32 infants had extrahepatic biliary atresia (EHBA) and 103 had hepatitis. No cause for the lesion was found in infants with extrahepatic biliary atresia, but in 32 with hepatitis a specific cause was identified, 24 having genetic deficiency of the serum protein alpha1-antitrypsin. No differences were observed in parental age, mother's health in pregnancy, month of birth, birth order, or sex of the infants. Familial idiopathic hepatitis occurred in 3 of 67 sibs of patients with idiopathic hepatitis, but the 33 sibs of EHBA patients had no liver disease. Of the infants with hepatitis, 36 were of low birthweight, less than 2.5 kg, and 23 were born prematurely. Infants with biliary atresia were all of normal birthweight and only one was born prematurely. Consideration of clinical and biochemical abnormalities in the first 2 months of life showed no differences between the two groups except that infants with EHBA were more commonly jaundiced from birth (80%) and had more frequently acholic stools (83%). The frequency of these features in patients with hepatitis being 68% and 52%. Standard tests of liver function were not discriminatory. Percutaneous liver biopsies were diagnostic in 75% of those with EHBA and in 92% of those with hepatitis. The I131 Rose Bengal faecal excretion was less than 10% in 26 of 28 infants with EHBA and in only 5 of 18 with hepatitis. These latter two investigations together allowed a correct preoperativer diagnosis of EHBA in all instances. Bile drainage was achieved surgically in only 3 cases. A major reason for these poor results may have been the late referral of cases for diagnosis and laparotomy, which should be performed as soon as the diagnosis is suspected and always by 70 days of age.     

Role of reovirus type 3 in persistent infantile cholestasis

The relationship between reovirus type 3 and persistent infantile cholestasis was studied by measuring antibody to the virus in the sera of affected and control babies younger than 1 year of age. One hundred sixty-seven infants were divided into four groups: those with extrahepatic biliary atresia, idiopathic neonatal hepatitis, or other cholestatic disorders, and controls. When available, maternal sera obtained simultaneously with infant sera were also studied. The results indicate that 62% of babies with extrahepatic biliary atresia and 52% of infants with idiopathic neonatal hepatitis have reovirus 3 antibodies. In contrast, less than 12% of either normal infants or babies with other cholestatic disorders have antibodies. These observations suggest that perinatal infection with reovirus type 3 may serve as an initiating event in the genesis of two closely related forms of infantile obstructive cholangiopathy: extrahepatic biliary atresia and idiopathic neonatal hepatitis.     

Evaluation of mebrofenin hepatoscintigraphy in neonatal-onset jaundice

Background. The prognosis of infants with prolonged neonatal jaundice is dependent on early diagnosis because of the need for prompt surgical management of biliary atresia. Objective. To evaluate the usefulness of ^{99 m}Tc^m-trimethylbromo-iminodiacetic acid (TBIDA, mebrofenin) in the investigation of infantile jaundice. Materials and methods. A retrospective study was undertaken of 58 patients with unexplained prolonged neonatal jaundice. Sixty-eight scans were reviewed. Results. Mebrofenin scintigraphy confirmed the presence of a choledochal cyst in three of the four cases with that diagnosis. There were no false negative results in the nine patients with extrahepatic biliary atresia (EHBA). Three further infants had an incorrect histological diagnosis of EHBA. A gall bladder was identified by US in each case and in one of these, scintigraphy showed gut excretion. In the 16 patients with no gut excretion by 24 h, the final diagnoses were intrahepatic cholestasis (n = 7), Alagille's syndrome (n = 3), neonatal hepatitis (n = 3), alpha-1-antitrypsin deficiency (n = 2) and juvenile xanthogranuloma (n = 1). Seven infants had repeat scintigraphy after the administration of ursodeoxycholic acid (URSO). This changed five non-excretors with hepatitis into excretors. Two infants with hepatitis continued to show non-excretion after URSO, but a gallbladder was identified by US in both. Conclusions. Mebrofenin scintigraphy is accurate in confirming the presence of a choledochal cyst and in refuting the diagnosis of EHBA. While histology and scintigraphy are each 100 % sensitive for the diagnosis of EHBA, neither, individually, is accurate and the investigation of prolonged neonatal jaundice requires a multi-modality imaging strategy. Received: 15 January 1998 Accepted: 8 April 1998     

Hepatobiliary scintigraphy and the string test in the evaluation of neonatal cholestasis

We evaluated [99mTc]diisopropylphenyl-carbamoylmethylimidodiacetic acid ([99mTc]DISIDA) cholescintigraphy with measurement of duodenal fluid radioactivity collected by the string test in patients with neonatal cholestasis. Twenty-six infants with prolonged jaundice and acholic stools were studied prospectively. Twelve patients had neonatal hepatitis, 12 biliary atresia, and one each Alagille syndrome and alpha 1-antitrypsin deficiency liver disease. All infants except the biliary atresia patients and four of the neonatal hepatitis patients revealed bowel activity on scan 6 h after tracer administration. At 24 h, three of these latter patients with neonatal hepatitis and two of the patients with biliary atresia revealed bowel activity. String radioactive counts for neonatal hepatitis ranged from 99,574 to 967,205 cpm (374,504 +/- 232,210 cpm; mean +/- SD) and for biliary atresia from 8,342 to 370,346 cpm (117,149 +/- 98,698 cpm; mean +/- SD). While neither test alone was capable of correctly differentiating among all patients, those patients with biliary atresia had either a negative hepatobiliary scan at 24 h or string radioactive count below 197,007 cpm. Disparity between the hepatobiliary scan and the string radioactive counts mandates further diagnostic investigation. These data suggest that simultaneous administration of the string test with hepatobiliary scintigraphy is advantageous in the evaluation of infants with cholestatic jaundice.     

Neonatal hepatitis and extrahepatic biliary atresia associated with cytomegalovirus infection in twins.

Prenatally acquired cytomegalovirus infection in twins was temporally associated with a discordant development of neonatal hepatitis and extrahepatic biliary atresia. This case presents evidence suggesting an association between perinatal cytomegalovirus infection and selected extrahepatic biliary atresia and neonatal hepatitis. Congenital cytomegalovirus infections and cytomegalovirus hepatitis are also discussed.     

Intestinal absorption of calcium and magnesium in hepatobiliary disease in infancy

The intestinal absorption of calcium and magnesium was measured by metabolic balance studies in 6 normal infants, 13 infants with biliary atresia, 5 infants with successfully repaired biliary atresia, 7 infants with neonatal hepatitis, and 2 infants with choledochal cyst. The absorption of both elements was impaired in these disorders. The malabsorption of these elements was most marked in biliary atresia. In successfully repaired biliary atresia the absorption was increased to the normal levels. In neonatal hepatitis the degree of the malabsorption was variable in individual cases. In choledochal cyst the reduction of the absorption was less marked than in biliary atresia and neonatal hepatitis. In biliary atresia parenteral vitamin D increased moderately the absorption of both elements, though oral vitamin D had little effect. In infants with biliary atresia receiving a milk containing medium-chain triglycerides the absorption was moderately raised. There was a clear relation between the absorption of calcium and that of magnesium: the per cent. absorption of magnesium was almost the same as that of calcium in most cases. The serum calcium level determined during the studies was within the normal ranges in hepatobiliary diseases. The serum magnesium level was, however, found to be generally reduced in these conditions. It was greatly reduced in the patients with biliary atresia.     

Alpha 1-antitrypsin deficiency (Pi SZ) and biliary atresia

We report an infant who presented at 2 days of age with conjugated hyperbilirubinemia. Serological, radiographic, and surgical investigations revealed the concurrence of alpha-1-antitrypsin deficiency, protease inhibitor type SZ, and extrahepatic biliary atresia.     

DIVERGENT PATTERNS OF EXTRACELLULAR MATRIX PROTEIN EXPRESSION IN NEONATAL VERSUS ADULT LIVER FIBROSIS

The extracellular matrix (ECM) expression is subject to distinct changes during ontogeny, and the natural course of liver fibrosis in neonates is thought to differ from that in adults. We compared the expression and distribution of main ECM components between neonatal and adult liver fibrosis. Liver biopsies from infants with neonatal cholestasis and fibrosis were compared to adult biopsies exhibiting an equivalent stage of fibrosis. All biopsies were examined by immunohistochemistry (indirect ABC method) for the ECM proteins, collagens I, III, IV, and VI, laminin, and fibronectin. Infants (aged 1-8 months) with neonatal hepatitis (n=3), extrahepatic biliary atresia (EHBA) (n=5), and normal histology (n=2) were compared with 9 adults (aged 17-70 years) with chronic hepatitis (n=3), primary biliary cirrhosis (PBC) (n=4), and normal histology (n=2). Collagens I, III, and IV and fibronectin were significantly increased in neonatal hepatitis with mild fibrosis (score ≤4) compared to adults with an equivalent fibrosis stage. This increase was particularly notable in perisinusoidal spaces. Laminin expression was increased in portal and perisinusoidal spaces both in neonatal hepatitis and extrahepatic biliary atresia with mild fibrosis. In infants with moderate to severe fibrosis (score ≥6), only collagen I was increased in comparison to adults, whereas collagen VI expression was identical in all groups, irrespective of the degree of fibrosis. Expression of matrix proteins was not different in infants and adults without fibrosis. The increased perisinusoidal deposition of certain ECM components in infants with active hepatitis and mild fibrosis may point to an underlying difference in the mechanism or stimulus of fibrogenesis in neonates as compared to adults.     

Bile acids in serum and bile of infants with cholestatic syndromes

The concentration of individual bile acids in serum was measured in 18 neonates and infants with various cholestatic conditions (extrahepatic biliary atresia, neonatal hepatitis syndrome, chronic intrahepatic cholestasis and posthemolytic cholestasis). The cholate/chenodeoxycholate ratio in serum was smaller than one in all patients with neonatal hepatitis syndrome or extrahepatic biliary atresia, cholestatic conditions which were accompanied by signs of liver cell injury. It was greater than one in the patients with chronic intrahepatic cholestasis. Administration of cholestyramine to patients with patent extrahepatic bile ducts decreased the total concentration bile acids in serum and elevated the cholate/chenodeoxycholate ratio. Thus, cholestyramine administration may be of diagnostic value for evaluation of bile duct patency in cholestasis of infancy. Differences between the bile acid pattern in serum and bile were observed. Thus, the cholate/chenodeoxycholate ratio was always higher in bile than in serum. 3beta-hydroxy-5-cholenoic acid found in serum was not detectable in bile. This finding suggests that impairment of biliary excretion rather than increased hepatic synthesis is responsible for elevation of this monohydroxy bile acid in serum.     

Diagnostic utility of hepatobiliary scintigraphy with 99mTc-DISIDA in neonatal cholestasis

We retrospectively evaluated the utility of hepatobiliary scintigraphy and various clinical factors in differentiating intrahepatic cholestasis from biliary atresia in 28 consecutive infants with neonatal cholestasis. One millicurie of technetium-labeled diisopropyliminodiacetic acid (DISIDA) was administered intravenously, and images were obtained for up to 24 hours or until gastrointestinal excretion was noted. Nine separate studies in seven infants with biliary atresia were correctly interpreted as showing no gastrointestinal excretion of radionuclide. Of the 21 patients with intrahepatic cholestasis, only nine had gastrointestinal excretion on the first study; in eight without excretion, a second study was done, and five of these showed gut excretion. All infants with either neonatal hepatitis (six) or inspissated bile syndrome (three) had demonstrable gastrointestinal excretion either on the first or second DISIDA study. However, five of six infants with paucity of intrahepatic bile ducts, two of six infants with cholestasis secondary to total parenteral nutrition, and one infant with cholangiolitis did not show evidence of gastrointestinal excretion. The mean birth weight, mean gestational age, and mean weight at study were significantly greater (P less than 0.005) for infants with biliary atresia without excretion than for infants with intrahepatic cholestasis without excretion. The mean direct bilirubin concentration was 6.0 mg/dL for both infants with biliary atresia and infants with intrahepatic cholestasis without excretion; however, infants with excretion had a significantly lower (P less than 0.02) mean direct bilirubin value of 3.4 mg/dL. Excretion was noted in four infants with total bilirubin values greater than 10.0 mg/dL. The absence of gut excretion on the first DISIDA study was 100% sensitive but only 43% specific for biliary atresia. In infants without gut excretion of DISIDA, birth weight greater than 2200 g was 100% sensitive and 92% specific for biliary atresia. We conclude that DISIDA scanning, together with clinical data, is useful in differentiating extrahepatic from intrahepatic cholestasis. The absence of gut excretion on the first DISIDA study does not necessarily indicate extrahepatic obstruction; the study should be repeated if the diagnosis is not clear.     

Phenobarbital-enhanced hepatobiliary scintigraphy in the diagnosis of biliary atresia: two decades of experience at a tertiary center

Background

Hepatobiliary scintigraphy is highly sensitive for diagnosing biliary atresia; however, its specificity has varied in the literature from 35% to 97%.

Objective

The purpose of this study was to re-evaluate the accuracy of phenobarbital-enhanced hepatobiliary scintigraphy in differentiating biliary atresia from other causes of neonatal cholestasis.

Materials and methods

We retrospectively reviewed all hepatobiliary scans of infants with cholestasis at our institution from December 1990 to May 2011. Per our routine protocol the scans were obtained after pretreatment with phenobarbital (5 mg/kg/day for 5 days) to achieve a serum level of ≥15 mcg/ml. Normal hepatic uptake with no biliary excretion by 24 h was considered consistent with biliary atresia.

Results

One hundred eighty-six infants with 210 hepatobiliary scans composed the study group. Forty-three (23%) infants had the final diagnosis of biliary atresia. Hepatobiliary scintigraphy was 100% sensitive, 93% specific and 94.6% accurate in diagnosing biliary atresia. Of the 186, 39/111 (35.1%) term and 2/68 (2.9%) preterm infants had biliary atresia; two of seven children with unknown gestational age also had biliary atresia. Other diagnoses included neonatal hepatitis, total parenteral nutrition cholestasis, Alagille syndrome, cystic fibrosis, choledochal cyst, hypothyroidism, alpha-1 antitrypsin deficiency and persistent cholestasis of unknown etiology.

Conclusion

Phenobarbital-enhanced hepatobiliary scintigraphy is highly accurate in differentiating biliary atresia from other causes of neonatal cholestasis. Biliary atresia is rare in premature infants.     

Pre-operative time course changes in liver function tests in biliary atresia: Its usefulness in the discrimination of biliary atresia in early infancy

In order to investigate the possibility of early discrimination of extrahepatic biliary atresia from other cholestatic diseases, a series of results of liver function tests in infants with cholestatic diseases were reviewed. The results of routine liver function tests (LFT) recorded in patients' charts were reviewed within 12 weeks after birth in 47 infants with extrahepatic biliary atresia (BA), 10 infants with neonatal hepatitis (NH) and 130 age-matched control infants (CO) without cholestatic diseases. The mean of each test value for each week after birth was derived from the actual data examined in each infant. No differences were observed between BA and CO in the levels of aminotransferases within 2 weeks after birth. Total bilirubin and direct bilirubin levels were significantly different between BA and CO within 1 week after birth (16.1 ± 3.2 mg/dL vs 11.1 ± 4.5 mg/dL, 4.6 ± 2.6 mg/dL vs 0.7 ± 0.3 mg/dL, respectively) The direct bilirubin-total bilirubin ratio exceeded 25% within the first week in BA. The individual values of direct bilirubin (DB) exceeded 2 mg/dL within the first week in all infants with BA, while none of the individual values exceeded 1.6 mg/dL in CO. Gamma-glutamyl transpeptidase levels were significantly different between BA and CO at 4 weeks (432 ± 272 IU/L vs 79 ± 43 IU/L) and thereafter; and were significantly different between BA and NH at 6 weeks (314 ± 232 IU/l vs 69 ± 58 IU/L) and thereafter. These data suggest that the determination of direct bilirubin within 1 week after birth can detect extrahepatic biliary atresia patients from those with physiologic jaundice, and γ-glutamyl transpeptidase levels may discriminate BA from NH at no later than 6 weeks of age.     

Clinical aspects on neonatal cholestasis based on observations at a Swedish tertiary referral centre

The aim of the study was to investigate the clinical aspects of neonatal cholestasis. The medical records of 85 cholestatic infants were retrospectively reviewed. A majority of the patients were referred from other parts of the country. The most common diagnoses were extrahepatic biliary atresia (n = 30 patients), alpha₁-antitrypsin deficiency (n = 11) and progressive familial intrahepatic cholestasis (n = 11). On presentation, the biliary atresia group had higher mean serum values of bilirubin, G-GT and cholesterol than the patients with intrahepatic cholestasis, with no significant differences noticed for any other biochemical parameter. A lack of excretion on hepatobiliary scintigraphy was noticed in all investigated patients with biliary atresia, but also in 9 of 34 patients with intrahepatic neonatal cholestasis. There was no statistical correlation between the age at portoenterostomy and the outcome in patients with biliary atresia. However, both the detection of a partial flow on perioperative cholangiogram and the establishment of a non-icteric phase within 6 mo after the portoenterostomy correlated to a good outcome. Eight of 11 patients with progressive familial intrahepatic cholestasis were treated with a biliary diversion procedure, five of eight experienced a sustained cholestatic remission. Conclusions: Progressive familial intrahepatic cholestasis may be a more common cause of neonatal cholestasis in Sweden than reported elsewhere and that the experience with biliary diversion is positive. While early referral in patients with extrahepatic biliary atresia remains important, a portoenterostomy should be attempted also in patients referred after 3 mo of age.     

Ten minute radiopharmaceutical test in biliary atresia.

To provide an objective rapid means of excluding extrahepatic biliary atresia (atresia), a hepatic index was devised from the ratio of the net hepatic to cardiac distribution of 99mTc diisopropyl iminodiacetic acid or methylbrom iminodiacetic acid between 2.5 and 10 minutes after injection. The hepatic index was compared with subjective assessment of abdominal scintigraphy performed repeatedly over 24 hours. In 22 infants with hepatitis the hepatic index ranged from 5.03 to 14.9, one having no excretion on scintiscan. In 26 infants with atresia the index ranged from 0.49 to 4.26 and in two with paucity of intralobular bile ducts it was 1.85 and 3.69. None of these infants had excretion apparent on scintiscans. Similarly, low hepatic indices occurred in four infants with liver dysfunction but pigmented stools, three of whom had no excretion apparent on scintiscans. These preliminary studies suggest that a hepatic index of greater than 5 is much more rapid and as specific in excluding atresia as repeated abdominal scintigraphy.     

IMMUNE RESPONSES IN PATIENTS WITH OBSTRUCTIVE JAUNDICE OF INFANCY

ABSTRACT. To investigate possible involvement of immune responses in the pathogenesis of obstructive jaundice in infancy we measured antibody to liver specific lipoprotein (LSP) by radio immunoassay and immune complexes by their ability to bind Clq in sera from 16 patients with extrahepatic biliary atresia and 16 with neonatal hepatitis and 13 age matched controls. Anti-LSP was present in 6 of 16 with preoperative biliary atresia and 6 of 16 with hepatitis. Mean percentage Clq bound was higher in hepatitis (22 SD 15 %) than preoperative biliary atresia (11.1 SD 2.3 %). Nine of 16 hepatitis patients had elevated Clq binding as compared with 1 of 16 with biliary atresia. The highest value for anti-LSP and Clq binding were found in sera from patients with histologically severe hepatitis and hepotitis associated with specific viral or bacterial causes. Anti-LSP was significantly raised 5 months post-operatively in all of 6 patients with biliary atresia and poor biliary drainage but only 2 of 5 survivors. Elevated Clq binding was detected in 6 of 7 with poor drainage and 1 of 7 survivors at the same stage. Anti-LSP and Clq binding fell in 4 patients with neonatal hepatitis on recovery. These findings suggest that immunological mechanisms, possibly involving antibody to hepatocyte membrane components and immune complexes, may be involved in the pathogenesis of progressive liver disease in biliary atresia.     

Hepatic scintigraphy in management of infants and children with liver disease

Scintiscans of liver and spleen using technetium 99m sulphur colloid in 15 infants with extrahepatic biliary atresia and 11 infants with severe obstructive jaundice (7 with genetic deficiency of alpha 1-antitrypsin) showed similar hepatic size, pattern of isotope uptake, and splenic abnormality with no distinguishing features. In 37 older children with a variety of liver disorders, the scan was invaluable in showing filling defects in five instances. Selenomethionine was taken up not only by the two filling defects due to hepatoblastoma but also in a haemangioendothelioma. In the remaining patiens liver scanning confirmed hepatic abnormality and the necessity for more specific invasive diagnostic investigations.     

Hepatic scintigraphy in management of infants and children with liver disease.

Scintiscans of liver and spleen using technetium 99m sulphur colloid in 15 infants with extrahepatic biliary atresia and 11 infants with severe obstructive jaundice (7 with genetic deficiency of alpha 1-antitrypsin) showed similar hepatic size, pattern of isotope uptake, and splenic abnormality with no distinguishing features. In 37 older children with a variety of liver disorders, the scan was invaluable in showing filling defects in five instances. Selenomethionine was taken up not only by the two filling defects due to hepatoblastoma but also in a haemangioendothelioma. In the remaining patiens liver scanning confirmed hepatic abnormality and the necessity for more specific invasive diagnostic investigations.