Functional Endoscopic Sinus Surgery (FESS) is the most common major ENT procedure in India. Here is what you actually need to know. When is FESS indicated over medical management? After 12 weeks of maximal medical therapy (nasal steroids + antibiotic for acute exacerbation + saline irrigations) with persistent CT-confirmed disease. Immediate surgical consideration for: allergic fungal sinusitis, antrochoanal polyp causing complete obstruction, sino-orbital or intracranial complications. CT or MRI — which imaging before FESS? CT paranasal sinuses (coronal + axial) is mandatory. Do it after treating an acute exacerbation to get a true baseline. MRI adds value only when you suspect fungal sinusitis, soft tissue extension into orbit, or intracranial involvement. Do not operate on plain X-ray findings alone. Is image-guided surgery (IGS/navigation) necessary for all cases? Not for straightforward cases. IGS is strongly recommended for revision FESS, extensive polyposis with distorted anatomy, skull base involvement, sphenoid sinus disease, and any case where your anatomical confidence is low. It reduces CSF leak and orbital injury risk significantly in complex cases. What are the most common intraoperative complications to watch for? Orbital fat exposure (most common, manage conservatively if limited), CSF leak (most serious, repair immediately with free mucosal graft), bleeding from anterior ethmoidal artery, and damage to nasolacrimal duct. Always identify the lamina papyracea and skull base before deepening dissection. Packing or no packing post-FESS? Trend is toward absorbable hemostatic agents (Surgicel, Nasopore) or no packing at all in uncomplicated cases. Non-absorbable Merocel pack if significant bleeding risk. Remove within 48 hours if used. Immediate post-op saline irrigation from Day 1 improves mucociliary clearance and reduces crusting. How long do patients need post-op follow-up? Endoscopic debridement at 1 week, 3 weeks, 3 months, and 6 months is standard. Relapse rate in CRS with polyps is 15–40% at 5 years. Long-term nasal steroids post-FESS reduce polyp recurrence. For allergic fungal sinusitis, oral steroids post-op are essential to prevent early recurrence.