Materials and methods
This is a cross-sectional study of TSBA levels in pregnant women
attending Florence Careggi University Hospital, a tertiary referral
Maternity hospital. Healthy pregnant women at term admitted to the
Obstetrics Department between 2020 and 2021 were offered participation.
The reference population was defined “healthy”, after excluding women
with a pathology for which there is an association with the measurement
being considered.
Inclusion criteria were singleton pregnancy; gestational age at or above
37 weeks; body mass index (BMI) between 17 and 40 kg/m².
Exclusion criteria were the presence of an established diagnosis of ICP
or abnormal liver function tests at any time throughout the pregnancy.
We also excluded any co-existing condition of increased risk for ICP
such as: multiple pregnancy; personal history of ICP; personal history
of liver disease (such as history of hepatitis B and C);
cholecystectomy; history of gastric bypass surgery; and the inability to
provide informed consent.
Both fasting (after 8-14 hours of fasting at 8 A.M.) and postprandial (2
hours after meal at 2 P.M.) TSBA were measured. The limited time frame
in which the blood samples could be sent to the laboratory, as well as
the dynamic nature of the obstetrics department, was the main limit to
patients’ inclusion. Not all the potential candidates eligible for the
study could participate or give an informed consent. In particular,
pregnant women who were sent to the delivery room before the blood
sample was taken could not participate.
For each patient, both venous blood samples were collected whenever
possible compatibly with the needs of the laboratory (as specified
above), otherwise only one of the two blood samples was taken.
TSBA levels correspond to the sum of more than 20 individual bile
acids21, and were estimated by
enzymatic-spectrophotometric assay, based on microbial 3α hydroxysteroid
dehydrogenase. Blood samples were analysed using Total Bile Acids Assay
Kit (Sentinel Diagnostics CH. SpA, Milan, Italy) at the Careggi hospital
clinical laboratory.
TSBA values were included for reference interval calculation, according
to the International Federation of Clinical Chemistry and Clinical and
Laboratory Standards Institute C28-A3 recommendations. An abnormal level
was defined as a value exceeding the upper reference limit
(97.5th)32,35, as there is no known
clinical significance to low levels of TSBA. In our laboratory, the
normal range of TSBA in the general population lies between 0 and 6
µmol/L.
The laboratory results were collected in a database along with maternal
and pregnancy characteristics. This information was obtained upon
admission, as part of the information routinely collected for
hospitalization. Patients were then followed-up until delivery, and data
regarding the delivery and neonatal outcome were collected.