Monopolar Curved Scissors (da Vinci)
Monopolar curved scissors provide mechanical cutting and optional monopolar energy. The distinction matters: an unactivated, cool blade can divide tissue without intentionally delivering electrosurgical energy, but a recently activated blade may still transmit heat.
Configuration and Preparation
The X/Xi baseline instrument is 8 mm and is commonly called Hot Shears. SP scissors and other platform variants are separate devices; confirm the actual instrument and accessory requirements.[1][2]
For the X/Xi instrument described in the manufacturer manual, the single-use tip cover is required, correctly fitted and undamaged. The reusable scissors and disposable cover have different lifecycles. Inspect the instrument and insulation; do not attempt to compensate for damage by changing energy settings.[2]
The scissors are commonly held in the surgeon's right-hand arm with a bipolar grasper on the left. They use the same 8 mm EndoWrist chassis as the bipolar instruments and needle drivers. Monopolar energy needs a patient return electrode.[2]
Three Modes in One Instrument
| Mode | How it is used | Best for |
|---|---|---|
| Cold sharp | Blade closure, no pedal | Plane dissection near nerves, ureter and repair lines; no deliberate thermal spread |
| Blunt spread | Closed tip inserted, then opened | Developing areolar planes |
| Monopolar cut | Cut pedal (lower-voltage continuous waveform) | Dividing tissue with less desiccation than coagulation |
| Monopolar coagulation | Coag pedal (higher-voltage intermittent waveform) | Desiccation of small bleeders; weak, because no tissue is compressed |
Reconstructive Role
Typical uses include the peritoneal incision, sigmoid mobilization, vaginal tunnel and promontory exposure in sacrocolpopexy; distal ureteral mobilization and bladder-flap raising for reimplantation, Boari flap or psoas hitch; plane dissection between mesh and bladder, bowel or vagina; and fistula-tract delineation. Cold sharp or cut-mode dissection is generally preferred near the ureter and repair lines.
| Task | Consideration |
|---|---|
| Fine division during ureteral, bladder or fistula reconstruction | Cold sharp cutting may help preserve the intended plane and avoid deliberate thermal treatment. Confirm that the blade has cooled after any prior activation. |
| Selective hemostasis during exposure | Use energy only when appropriate for the tissue and nearby structures; this instrument is not a calibrated vessel sealer. |
| Dissection near nerves, ureter, bowel or a vascularized flap | Consider cold scissors with pressure, clips or sutures. A generic energy ranking or millimeter clearance cannot guarantee preservation. |
| Pedicle division | Use the vascular-control method appropriate to the vessel and procedure, including a dedicated sealer when indicated. |
The arm position and complementary Maryland, fenestrated bipolar or retractor should be chosen for exposure and tissue handling rather than a universal three-instrument prescription.
Activation and Stray Energy
Monopolar current requires the appropriate patient return circuit. Unintended energy can reach tissue through direct contact, damaged insulation or coupling to other conductive instruments. Maintain a visible target, avoid open-air activation and avoid using the energized shaft or wrist as a retractor. Follow the platform's cannula and reducer restrictions rather than assuming that any metal or plastic combination is acceptable.[2][3]
Overbey's trainer experiment used a monopolar L-hook with da Vinci Si instruments, not a clinical trial of these scissors. Lower power, low-voltage cut mode and contact with intended tissue reduced measured stray heating. In that model, open-air 30 W coagulation raised the temperature at the adjacent assistant grasper by 18.3 ± 5.8 °C and at the camera tip by 9.0 ± 2.1 °C. Reducing power to 15 W (2.6 ± 2.7 °C), using low-voltage cut mode (3.1 ± 2.1 °C) or activating on desiccating tissue instead of open air (0.15 ± 0.21 °C at the grasper) all reduced transfer. This supports disciplined energy use but does not prescribe a universal 15 W setting or make cut mode harmless.[3]
Do not use one energized instrument to energize or clean another. Keep non-target tissue away from the working end and allow for residual heat. For implanted cardiac devices, return-pad planning and operating-room fire and smoke precautions, see Energy Devices.[2]
Interpreting Thermal Studies
- Hefermehl 2014: in bovine musculofascial tissue at 60 W, monopolar critical thermal spread (to 45 °C) was 3.5 mm at 1 s and more than 20 mm at 2 s, versus 2.2 and 3.6 mm for adjustable bipolar. Brief activations therefore matter. The threshold and distances are not validated clinical nerve-injury boundaries. A metal heat sink tested in that setting is not a standard near-nerve technique.[4]
- Brinkmann 2022: residual heat was studied in a laparoscopic hook and endoscopic knives on porcine stomach. The hook could remain above 50°C for at least 15 seconds; that finding does not establish a universal scissors cooling interval.[5]
- Wikiel 2023: 36 hernia patients underwent laparoscopic or robotic surgery with protocol biopsies. Microscopic thermal changes occurred in 59 of 108 sampled biopsies. These are biopsy findings with uncertain clinical significance, not a 54% rate of clinically apparent burns.[6]
Practical Limits
Mechanical sharpness, intact insulation, the appropriate cover, exposure and deliberate activation are more useful than memorizing a single temperature, wattage or cooling time. Stop using a damaged instrument and follow the manufacturer's replacement, cleaning and reprocessing instructions.
See also: Monopolar Cautery Hook, Electrosurgical Pencil, Harmonic ACE.
References
1. Intuitive. Da Vinci X/Xi instrument and accessory catalog: 8 mm monopolar instruments. Manufacturer catalog.
2. Intuitive. Da Vinci Xi and X Instruments and Accessories User Manual, 553873-07 Rev. D. Chapter 7. Manufacturer manual.
3. Overbey DM, Carmichael H, Wikiel KJ, et al. Monopolar stray energy in robotic surgery. Surg Endosc. 2021. doi:10.1007/s00464-020-07605-5.
4. Hefermehl LJ, Largo RA, Hermanns T, et al. Lateral temperature spread of monopolar, bipolar and ultrasonic instruments for robot-assisted laparoscopic surgery. BJU Int. 2014;114:245–252. doi:10.1111/bju.12498.
5. Brinkmann F, Hüttner R, Mehner PJ, et al. Temperature profile and residual heat of monopolar laparoscopic and endoscopic dissection instruments. Surg Endosc. 2022. doi:10.1007/s00464-021-08804-4.
6. Wikiel KJ, Bollinger D, Montero PM, et al. Stray energy injury during robotic versus laparoscopic inguinal hernia repair: a randomized controlled trial. Surg Endosc. 2023. doi:10.1007/s00464-023-10331-3.