Introduction: Bilateral inferior petrosal sinus sampling (BIPSS) is the test that offers the highest diagnostic accuracy in the differential diagnosis between pituitary and ectopic Cushngs syndrome (CS). The aim of this study was to compare the diagnostic accuracy of BIPSS performed in the last six years, after the change in the technical procedure with that performed in the past period in Naples centre.
Patients and methods: Seventeen patients with CS (14 patients with pituitary and 3 with ectopic CS) followed-up in our institution between 2007 and 2012 were compared with 10 retrospective patients with pituitary-dependent CS subjected to BIPSS. The change in technical procedure was the use of 4-french (instead of 5-french) hydrophilic-coated vertebral catheters introduced into femoral veins using the Seldinger technique.
Results: In the ten historical patients BIPSS yielded 3 (30%) false-negative, together with a discordant result between baseline and post-CRH stimulation in one case, whereas side-to-side (S/S) gradient indicating a correct lateralization in nine patients (90%). In the 17 recent patients, no false-negative or false positive cases were observed, although in one case an IPS/periphery (P) gradient was found only at baseline evaluation. Moreover, a S/S ratio correctly indicated the lateralization of the lesion in 100% cases. The mean post-CRH IPS/P (P<0.01) gradient was significantly higher in recent than historical patients, although no significant difference was found in mean IPS/P and S/S gradient at baseline evaluation. Sensitivity, specificity and predictive value of BIPSS in the recent group was of 100%, whereas sensitivity and positive predictive values were 70 and 100% in the historical group.
Conclusions: In Naples experience the diagnostic value of BIPSS has been improved in the last years likely due to the introduction of new catheters, permitting to reach a diagnostic accuracy and a predictivity of 100% cases.