trephineneedle

Trephineneedle is a specialized medical instrument used to obtain a cylindrical core of bone and marrow tissue, typically for diagnostic evaluation. It belongs to the family of trephine needles used in bone marrow biopsy procedures. The instrument is usually designed as a hollow, cannulated needle with a cutting tip or inner core that can be advanced into the bone and then withdrawn to retain a core sample for histology.

During the procedure, a local anesthetic is administered and the patient is positioned to access a suitable site, most commonly the posterior iliac crest. After aseptic preparation, the needle is inserted through the cortical bone into the marrow cavity; the cut core is captured within or alongside the needle and later expressed for examination. This core provides architecture of the marrow in addition to cellular details obtained from aspirates. Trephine biopsy with this needle is often used when assessment of marrow architecture is required, such as evaluation of cellularity, fibrosis, and infiltration by disease.

Trephine needles are used in hematology, oncology, and pathology to diagnose conditions such as anemia, leukemia, myelodysplasia, myeloproliferative disorders, marrow infiltration by solid tumors, and infectious or granulomatous diseases. They are often used in conjunction with a marrow aspirate to improve diagnostic yield. Risks include pain, bleeding, infection, and, rarely, injury to surrounding structures. Contraindications include active infection at the puncture site and uncorrected coagulopathy; the procedure should be performed under sterile technique and, when indicated, with imaging guidance. Historically, trephination describes creating a circular bone hole; trephine needles evolved to obtain aligned bone cores for histology, enhancing marrow evaluation.