Correct Answer: C. Trocar and cannula for laparoscopy
The instrument depicted is a trocar and cannula, the hallmark access instrument used in laparoscopic surgery. A trocar consists of a sharp-pointed obturator (the trocar itself) housed within a hollow cylindrical sleeve (the cannula). Together, they are used to puncture the abdominal wall and establish a working port through which the laparoscope and other instruments are introduced into the peritoneal cavity. The primary trocar (typically 10–12 mm) is inserted at the umbilicus after creation of pneumoperitoneum with a Veress needle, while secondary trocars (5 mm) are placed in the iliac fossae under direct vision.
In gynaecology, the trocar and cannula are indispensable for diagnostic and operative laparoscopy — including evaluation of pelvic pain, endometriosis, ectopic pregnancy, ovarian cysts, and laparoscopic sterilisation. The distinctive design features — a conical or pyramidal sharp tip, a locking mechanism on the cannula, and a trumpet/flap valve to prevent gas escape — make this instrument immediately recognisable as a laparoscopic access device. Modern disposable trocars may have a safety shield that retracts on entry and springs back to cover the blade, reducing visceral injury risk.
Recognition of this instrument is a high-yield topic in NEET PG OBG, as laparoscopy is now the gold standard for many gynaecological procedures. The trocar and cannula are the entry instruments that make the entire laparoscopic approach possible.
Why other options are wrong
- A. Bone marrow biopsy set — Bone marrow biopsy uses a Jamshidi needle or Salah needle — a hollow needle with a stylet designed for sternal or iliac crest puncture. These are entirely different in design and purpose from a trocar and cannula.
- B. Punch Biopsy — Punch biopsy employs a small circular cutting instrument used to obtain cylindrical tissue cores from skin or mucosa. It bears no resemblance to the trocar-cannula assembly used for abdominal access.
- D. Tubectomy (Female Sterilisation) — While tubectomy can be performed laparoscopically (using trocars for access), the specific instrument depicted — the trocar and cannula — is the access/entry device, not the operative instrument used for tubal occlusion. Tubal sterilisation uses Falope rings, Filshie clips, or electrocautery applied through the cannula. The trocar and cannula belong to laparoscopy as a technique, not exclusively to tubectomy.