TissueDB/Simulators/Laparoscopic Cholecystectomy Simulator (Casas-Murillo)

The Laparoscopic Cholecystectomy Simulator (Casas-Murillo) is a low-cost, in-house trainer — built from 3D-printed molds and silicone casts — for the dissection and anatomical-recognition steps of laparoscopic cholecystectomy.^[1] A silicone-rubber cast of the gallbladder, extrahepatic bile ducts and cystic artery is mounted on hard 3D-printed liver and duodenum scaffolds and dissected through a layered connective-tissue overlay. The published model set covers one normal cystic-duct configuration plus three insertion variants — distal insertion with parallel trajectory, medial middle-third insertion, and medial distal-third insertion — so trainees rehearse the anatomical-variation recognition that governs safe dissection at the hepatic hilum.

1. Acquire a magnetic resonance cholangiopancreatography study from the radiological archive on a 1.5 T scanner. The source paper used a General Electric SIGNA HDxt LX-MR with an FRFSE-XL pulse sequence, respiration-triggered MRCP ASSET acquisition: 256 slices at 1.4 mm thickness, 0.7 mm interslice gap, field of view 29, matrix 256 × 256, NEX 1, TE 452, TR 3000, acquired on an oblique plane. Select one normal cystic-duct anatomy plus three variant anatomies (distal insertion with parallel trajectory, medial middle-third insertion, medial distal-third insertion).
2. Acquire an arterial-phase axial computed-tomography study for the liver, duodenum and cystic artery using 1.2 mm slice thickness with 0.635 mm interval.
3. Segment the DICOM data in 3D Slicer version 4.8.0 and export to STL. Post-process the STL to smooth edges and correct segmentation imperfections in Autodesk Meshmixer 3.5.474. For the liver and duodenum, retain only the organ contours to ease mould assembly and save printing material.

1. Print the hepatic segment V and VI contours and the second portion of the duodenum on a Zortrax fused-deposition-modeling printer in ABS (acrylonitrile butadiene styrene) filament. Colour the printed replicas after the print finishes.
2. Design a two-part negative mould for the gallbladder and bile ducts in SolidWorks 2016. Place the gallbladder and bile ducts on the same plane so a straight line can be traced through the centres of the structures — this is what allows the two-part mould to release.
3. Print the two-part negative moulds in ABS on the same fused-deposition-modeling printer.
4. For the medial-insertion cystic-duct variants, separate the negative-mould design into two moulds — one for the gallbladder and cystic duct, one for the rest of the extrahepatic bile ducts — because the normal anatomical loop around the common bile duct prevents a single complete two-part mould from releasing cleanly. Attach the two cast pieces after casting (Phase 3).

1. Mix P53 silicone rubber with the desired colorant, then pour the mixture into the ABS negative mould.
2. Allow the silicone to solidify, evacuate the silicone replica from the mould, and cleave any asperities caused by silicone flowing out unintentionally.
3. Cast the cystic artery together with the right hepatic artery in its dedicated two-part ABS mould. No anatomical variants are required for this cast.
4. For the medial-insertion variants, use the adherent properties of liquefied P53 silicone: cast the gallbladder-and-cystic-duct piece first, then attach it to the bile-ducts mould and apply additional silicone over the join to form a single continuous structure.

1. Adapt a metallic box (40 × 30 × 20 cm) with three laparoscopic-port openings on the top face and a front hole sized for an endoscopic USB camera. Connect the camera to a computer for real-time intracavity video.
2. Install internal lighting inside the chassis.
3. Set out the laparoscopic graspers and any other instruments needed for the rehearsed steps of laparoscopic cholecystectomy.

1. Place the ABS liver and duodenum scaffolds inside the chassis. Connect the silicone-cast extrahepatic biliary system to the scaffolds using screws and wires so the structures sit in normal laparoscopic-surgical position.
2. Pull the gallbladder over the liver using a wire — this stands in for an assistant during real laparoscopic cholecystectomy.
3. Staple the cystic artery to the gallbladder. Connect the right hepatic artery to its anatomic insertion in the liver scaffold at the hepatic hilum.

1. Apply yellow-coloured commercial slime (Elmer's Slime) in layers to simulate (a) the fibrous tissue connecting the gallbladder neck to the liver, (b) the hepatoduodenal ligament, and (c) the tissue between the cystic artery and the cystic duct. The slime is what gives the trainee something to dissect through during the rehearsal.
2. Verify the workspace temperature is held at 25 °C or cooler before each rehearsal. At warmer temperatures the slime melts over the moulds and the dissection target is lost; if the room cannot be held at this temperature, plan for a shorter rehearsal cycle or pre-cool the chassis.

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