Pathological Variables and Laboratory Values in Infants with Neonatal Cholestasis Showing Nonexcretion on Tc-99m Mebrofenin Hepatobiliary Scans: A Descriptive Study.

Introduction: Cholescintigraphy using Tc-99m Mebrofenin is routinely performed as an initial diagnostic test in infants with neonatal cholestasis suspected of having biliary atresia. Demonstration of drainage of bile into the small intestine indicates patency of the biliary tract and thus rules out biliary atresia. Non-excretion of tracer into the small intestine, however, can be caused by obstructive as well as non-obstructive conditions, and it is known that false-positive findings are found with the use of Tc-99m Mebrofenin scintigraphy.

Aim: In the present study, we retrospectively calculated the proportion of infants eventually diagnosed to have biliary atresia that were initially ruled to have a non-excreting cholescintigraphy pattern in our institution. We have also attempted a systematic description of the cardinal histological characteristics, haematological and hepatic biochemical variables in infants with non-excreting patterns.

Materials and methods: This retrospective, descriptive study was conducted in Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry. We reviewed data from infants who underwent cholescintigraphy with Tc-99m Mebrofenin between January 2016 through June 2022. We included infants in whom the scan was ruled "non-excreting" i.e. those infants in whom biliary atresia could not be ruled out based on the results of the scan. The difference in mean for haematological parameters and ALP were compared between the two groups i.e., biliary atresia versus other than biliary atresia by using Independent student's t-test; the remaining liver biochemical parameters were compared by using Mann-Whitney U Test and a p value < 0.05 was considered to be statistically significant.

Results: A non-excretory pattern on cholescintigraphy was found to be due to biliary atresia in 49% of cases (as confirmed by exploratory surgery) and an additional 19.6 % of cases by trucut biopsy (total 68.6%). The difference in the mean serum GGT levels was found to be statistically significant (<0.001).

Conclusion: A non-draining pattern on cholescintigraphy is caused by biliary atresia in the greater percentage of cases presenting with cholestasis. The difference in mean GGT levels was found to be statistically significant between biliary atresia and other causes of non-draining patterns on cholescintigraphy.