Inferior Petrosal Sinus Sampling (IPSS) is a medical procedure used to help locate the source of excess adrenocorticotropic hormone (ACTH) production.
The technique involves a series of specific steps focused on accessing and sampling blood from the veins draining the pituitary gland.
Here is a breakdown of the key steps based on the provided reference:
- Venous Access: The procedure begins with the cannulation of the bilateral femoral veins. This means inserting thin tubes (catheters) into the veins located in both groins.
- Catheter Advancement: The catheters are then advancing into the inferior petrosal sinuses via the internal jugular veins. This is a delicate process guided by imaging (like fluoroscopy) to navigate the catheters from the femoral veins up through the body, into the internal jugular veins in the neck, and finally into the small veins (inferior petrosal sinuses) located near the pituitary gland at the base of the skull.
- Baseline Sampling: Before any stimulation, baseline ACTH values are obtained from the periphery (usually a vein in the arm) and the inferior petrosal sinuses (from the catheters positioned there).
- CRH Stimulation: A dose of corticotropin-releasing hormone (CRH) is administered. The dose used for stimulation is typically 1 μg/kg of body weight. CRH is a hormone that stimulates the pituitary gland to release ACTH.
- Post-Stimulation Sampling: After CRH administration, additional blood samples are collected. ACTH values are obtained from the periphery and the inferior petrosal sinuses both before and after CRH stimulation. Samples are taken at specific time points (though the reference only states "before and after").
By comparing the ACTH levels in the inferior petrosal sinuses (which drain the pituitary) to the levels in the periphery, doctors can determine if a pituitary tumor is the source of excess ACTH and often pinpoint the side of the pituitary where the tumor is located.
Summary of Sampling Points:
| Sampling Location | Timing |
|---|---|
| Peripheral Vein | Before CRH, After CRH |
| Left Inferior Petrosal | Before CRH, After CRH |
| Right Inferior Petrosal | Before CRH, After CRH |
This procedure requires expertise in interventional radiology and endocrinology and is performed in a specialized medical facility.
