# A needle in a haystack: Assessing the radiographic detectability of microsurgical suture needles using a human cadaveric model

## TL;DR

This study shows that X-rays can detect larger surgical needles but fail to detect very fine microsurgical needles, suggesting a need for better protocols.

## Contribution

The study quantifies the radiographic detectability of microsurgical needles in a human cadaveric model.

## Key findings

- X-ray imaging reliably detects needles of 3–0 to 6–0 calibers with over 99% accuracy.
- Needles of 8–0 and finer are rarely detected, with 8–0 needles identified in only 3.77% of attempts.
- No 10–0 needles were detected in any anatomical site.

## Abstract

Intraoperative loss of surgical needles represents a rare but significant challenge in operative settings, particularly in microsurgical procedures involving free tissue transfer where fine sutures (8–0 to 10–0) are employed. Current hospital protocols typically use intraoperative portable radiography to localize misplaced needles. However, the diagnostic utility of X-ray imaging in detecting small-caliber needles remains poorly defined.

Following ethical approval, a cadaveric study was conducted using a range of monofilament Ethilon™ needles (3–0 to 10–0 caliber), which were inserted at four anatomically relevant surgical sites. Anteroposterior radiographs were obtained using a standard intraoperative C-arm. A total of 53 participants - including consultant surgeons, radiology trainees, nursing staff, and surgical registrars—were asked to identify needle number and location using blinded image review. Radiographic identification of needles was accurate for calibers 3–0, 4–0, 5–0, and 6–0, with identification rates approaching or exceeding 99%. Smaller needle calibers showed a dramatic decline in detection accuracy. The 8–0 needles were correctly localized in 3.77% of attempts, just one 9–0 needle was successfully identified. None of the 10–0 needles were detected across all anatomical sites.

While portable radiography remains a reliable modality for locating surgical needles of caliber 3–0 to 6–0, it proves ineffective for the detection of finer microsurgical needles (≥8–0). These results have important implications for operative protocols and clinical decision-making. The routine X-ray imaging in cases of microsurgical needle loss warrants reconsideration to favor evidence-informed strategies that minimize intraoperative delays, prolonged anesthesia and unnecessary radiation exposure.