Robot-assisted Cyst Excision, Ductoplasty, and Embedding Portoenterostomy for Choledochal Cysts with a Small Caliber Hepatic Duct less than 6 mm

Summary

Anastomotic stricture is a primary concern following surgical treatment of choledochal cysts and is the main reason for re-operation. This study presents a robot-assisted synthetic technique designed to mitigate this risk.

Abstract

Anastomotic stricture is a primary concern following the surgical treatment of choledochal cysts (CC), particularly in pediatric patients with narrow bile ducts (<6 mm), and remains the main indication for re-operation. Robotic-assisted surgery (RAS), with its superior 3D visualization and instrument dexterity, offers an ideal platform for the complex reconstruction required to prevent this complication. This study presents a robot-assisted modified technique designed to mitigate the risk of stricture, as demonstrated in a 34-month-old female with a Type Ia CC. The procedure involves complete cyst excision followed by ductoplasty and an embedding portoenterostomy to create a broad anastomosis. During a median follow-up of 34 months in a cohort of 28 patients, no abnormal liver function tests, intrahepatic stones, cholangitis, or anastomotic strictures were observed. This technique creates a broad, tension-free portoenterostomy by shifting the scar line away from the lumen, providing an effective solution for treating CC patients with a small-caliber hepatic duct.

Introduction

Radical surgery for choledochal cysts (CC) has transitioned from traditional laparotomy to minimally invasive surgery to achieve faster recovery and shorter hospital stays¹. While laparoscopic-assisted surgery is often hindered by rigid instruments and 2D visualization within the narrow pediatric abdominal cavity, robotic-assisted surgery (RAS) overcomes these constraints with 3D visualization and multi-jointed dexterity, enabling precise, tension-free anastomosis^2,3. Furthermore, RAS is associated with a shorter learning curve for this complex surgical procedure compared to traditional laparoscopic techniques⁴. However, the risk of postoperative anastomotic stricture remains a significant challenge, particularly in patients with small anastomotic openings^5,6. Previous research in laparoscopic surgery has shown that performing an embedding portoenterostomy can effectively prevent anastomotic scarring, particularly when the hepatic duct opening is less than 6 mm^7,8. This threshold is based on the biological principle that an initial opening of 5-6 mm typically contracts to a functional diameter of only 3-4 mm during the natural cicatricial remodeling of conventional full-thickness reconstructions⁷. While the robotic system offers superior dexterity and visualization, it does not alter the fundamental biological processes of wound healing. Consequently, the laparoscopic-assisted approach was refined into a robot-assisted technique to optimize the benefits of this reconstruction in anatomically challenging cases. This technique is most appropriate for CC patients with narrow hepatic duct openings (<6 mm).

This report highlights the application of this advanced robotic technique in the case of a 34-month-old female diagnosed with a CC prenatally. The patient presented without symptoms such as fever, abdominal pain, jaundice, or vomiting. A follow-up abdominal ultrasound one month prior to surgery showed the CC measuring approximately 49.9 mm x 32.9 mm. Preoperative workup revealed that the patient had a concurrent infection and pancreatitis, for which antibiotic therapy was administered. Subsequent Magnetic Resonance Cholangiopancreatography (MRCP) showed no significant dilation of the intrahepatic bile ducts, but the common bile duct was significantly dilated, with a maximum transverse diameter of approximately 3.7 x 3.4 cm, while the liver, spleen, and pancreas appeared normal (Figure 1). These imaging findings were consistent with a diagnosis of a Type Ia choledochal cyst. The decision was made to proceed with robotic-assisted cyst excision and portoenterostomy. The following describes a standardized approach to this procedure, specifically designed for CC with a small-caliber hepatic duct opening measuring less than 6 mm. Informed consent was obtained from the patient's guardians prior to the surgery.

Protocol

This protocol complies with the guidelines of the Research Ethics Board of Union Hospital (2016-LSZ-S180). The reagents and the equipment used are listed in the Table of Materials.

1. Preoperative preparation, patient position, and anesthesia

1. Dietary management and prophylaxis
   1. Withhold solid foods for 8 h, formula milk for 6 h, breast milk for 4 h, and clear fluids for 2 h before the induction of anesthesia.
   2. Administer intravenous cefuroxime (30 mg/kg) as a prophylactic antibiotic 30 min prior to the surgical incision.
2. Anesthesia and monitoring
   ​NOTE: The selection of intravenous or inhaled anesthetic agents should be tailored to the patient's comorbidities and guided by institutional protocols.
   1. Induce general anesthesia and perform endotracheal intubation.
   2. Establish two peripheral intravenous lines for the primary administration of fluids and medications, and a second for backup access.
   3. Place an arterial line via cannulation for continuous invasive blood pressure monitoring and for arterial blood gas analysis as needed.
   4. Monitor the patient's core body temperature. Maintain normothermia throughout the procedure using a warming blanket and warmed intravenous fluids.
3. Catheterization
   1. Insert an 8 Fr nasogastric tube to ensure gastric decompression.
   2. Insert an 8 Fr sterile urethral catheter for bladder drainage.
      NOTE: Select the catheter size according to the age of the patient.
4. Place the patient in a supine position with a 15° reverse Trendelenburg (head-up) and a 15° left lateral tilt.
   ​NOTE: For young infants, elevate the body approximately 10 cm above the operating table to provide adequate clearance for the robotic arms.

2. Operation settings and port placement

1. Team and equipment setup
   1. Position the assistant surgeon on the patient's left side and the scrub nurse at the foot of the bed, behind the assistant surgeon.
   2. Configure endoscope settings according to the system's instructions. Pre-warm the endoscope in sterile warm water (not exceeding 55 °C) to prevent intraoperative fogging.
2. Pneumoperitoneum and port placement
   1. Make an 8 mm incision at the umbilicus and insert an 8 mm trocar for the camera port.
   2. Establish a carbon dioxide pneumoperitoneum and maintain the pressure at 10 mmHg.
      ​NOTE: Adjust pressure within 6-12 mmHg based on patient age and physiological tolerance.
   3. Insert the robotic endoscope and perform an initial inspection of the cyst and hepatic hilum.
   4. Create 8 mm transverse skin incisions for the working ports. Place the first 8 mm working port (R1) in the left upper quadrant, on the midclavicular line at a distance of approximately 5 cm from the umbilicus. Place the second 8 mm working port (R2) 4 cm below the right costal margin, at the umbilical level between the midclavicular and anterior axillary line (Figure 2).
   5. Insert a 5 mm assistant port (A1) in the left lower quadrant (Figure 2) for suction, irrigation, and suture passage.
3. To improve exposure of the hepatic hilum, place a 2-0 transabdominal suspension suture through the base of the round ligament for supero-lateral retraction toward the left upper quadrant.
4. Place a second 2-0 suture to retract the gallbladder fundus, providing superior and rightward retraction against the abdominal wall.

3. Construction of the Roux-en-Y limb

1. Identify the ligament of Treitz. Grasp the proximal jejunum with an intestinal grasper and extend the umbilical incision approximately 1.5 cm superiorly.
2. Bring out this segment of the jejunum through the extended incision to perform the division and anastomosis extracorporeally.
3. Divide the proximal jejunum 15 cm distal to the ligament of Treitz using a 60 mm linear cutting stapler to create the biliopancreatic and Roux limbs.
4. Perform a side-to-side stapled jejunojejunostomy 25 cm from the divided end of the Roux limb.
   NOTE: Adjust this distance between 20-30 cm based on the patient's anatomy and intraoperative findings.
5. Close the mesenteric defect created during the anastomosis with absorbable sutures to prevent internal herniation.
6. Return the bowel to the abdominal cavity.
7. Create a window in an avascular area of the transverse mesocolon, to the right of the middle colic artery. Pass the Roux limb in a retrocolic fashion through this window toward the porta hepatis.
8. Close the extended umbilical fascial and skin incisions, re-insert the camera trocar, and re-establish the pneumoperitoneum.

4. Choledochal cyst mobilization and excision

1. Position the robotic patient cart over the patient's right shoulder. Dock the robot, attaching the camera and working arms to the corresponding trocars.
2. Insert the robotic instruments. Insert a Maryland bipolar forceps into the R1 port and a monopolar cautery hook into the R2 port.
3. Mobilization of the cyst
   1. Retract the duodenum inferiorly through the assistant port (A1). Grasp the cyst wall with the Maryland bipolar forceps (R1) to provide counter-traction, exposing the anterior surface of the cyst.
      ​NOTE: Carefully control the vascular supply by identifying, clipping, and dividing the cystic artery before extensive mobilization.
   2. Dissect the anterior cyst wall using the monopolar hook (R2). Release adhesions between the cyst and pancreatic tissue down to the pancreaticobiliary junction.
   3. Transect the distal end of the cyst proximal to the pancreaticobiliary junction and secure the ductal stump using Hem-o-lok clips.
   4. Separate the cyst from the underlying hepatic artery and portal vein (Figure 3A).
   5. Once fully mobilized (Figure 3B), incise its anterior wall and aspirate the bile contents using a suction irrigator.
   6. Irrigate the common hepatic duct with normal saline to flush out any biliary sludge or calculi.
4. Cyst and gallbladder excision
   1. Dissect superiorly to the level of the common hepatic duct and transect the proximal end of the cyst.
   2. Trim the margins of the hepatic duct opening to ensure all cystic and inflamed tissue is removed.
   3. Perform a standard cholecystectomy, dissecting the gallbladder from the liver bed.

5. Ductoplasty and portoenterostomy

1. Preparation of the hepatic duct
   1. Measure the diameter of the common hepatic duct opening using a fixed-length non-absorbable suture (Figure 3C).
   2. Replace the current instruments with two large needle drivers in the R1 and R2 ports.
   3. Evert the wall of the residual hepatic duct by placing four 5-0 absorbable stay sutures. Place two sutures on the anterior wall and two on the posterior wall, securing the everted edge to the surrounding serosal layer of the bile duct (Figure 3D).
2. Incise the Roux limb longitudinally on the antimesenteric border at the distal end of the Roux limb.
3. Perform the portoenterostomy using two running 5-0 absorbable sutures. Suture the full thickness of the jejunal enterotomy to the Glisson's capsule surrounding the everted hepatic duct, beginning with the posterior wall (Figure 3E).
4. Complete the anastomosis by suturing the anterior wall.
   NOTE: This should create a wide, tension-free anastomosis (approximately 10 mm) with the residual hepatic duct wrapped within the intestinal lumen (Figure 3F).
5. Close the defect in the transverse mesocolon and fix the Roux limb to the colonic mesentery with absorbable sutures.
6. Thoroughly irrigate the anastomotic site to clear residual bile and inspect for active bleeding.
7. Undock the robot.
8. Remove the excised specimens through the camera port.
9. Place a surgical drain in the subhepatic space through the R1 port site.
10. Close all port site fascial defects and skin incisions in layers.

6. Postoperative evaluation and discharge

1. Perform liver function tests, a complete blood count, and an abdominal ultrasound prior to the planned discharge.
2. Discharge the patients once clinical stability is achieved, and a normal diet has been successfully resumed.
3. Schedule a postoperative follow-up appointment at the one-month follow-up.

Results

The detailed perioperative information for the case presented in the video is provided in Table 1 and Figure 2. The procedure was performed in November 2021 by the corresponding author using the robotic system. The estimated blood loss during the operation was 5 mL.

Postoperative management included antibiotic therapy for infection prophylaxis, hepatoprotective agents, and nutritional support. The surgical drain was removed once the output decreas...

Discussion

Complete cyst excision and hepaticojejunostomy are established as the definitive treatments of CC⁹. With advances in minimally invasive technologies, laparoscopic and robotic approaches are increasingly reported, demonstrating both feasibility and significant patient benefits^5,10. However, the laparoscopic technique presents inherent challenges, including a two-dimensional operative view, limited instrument mobility, and a steep learning c...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
12 Fr drain	Cliny (Dalian, China)	8000015091	Abdominal drainage
2-0 absorbable polyglactin suture	B. Braun surgical (SA)	111055	Absorbable Sutures
5-0 absorbable polyglactin suture	B. Braun surgical (SA)	725231	Absorbable Sutures
5mm Trocar	Intuitive (Sunnyvale, CA)	470361	Assistant port
8 Fr nasogastric tube	Cliny (Dalian, China)	8880004372	gastric decompression
8 Fr sterile urethral catheter	Cliny (Dalian, China)	8880260080	bladder drainage
8mm Trocar	Intuitive (Sunnyvale, CA)	470362	Working port
Da Vinci Xi	Intuitive (Sunnyvale, CA)	N/A	surgical robot
laparoscopic Bowel forceps	Shendr Siao (Zhenjiang, China)	SD301054F	Laparoscopic Surgical instruments
laparoscopic Grasping forceps	Shendr Siao (Zhenjiang, China)	SD301041F	Laparoscopic Surgical instruments
Large needle driver	Intuitive (Sunnyvale, CA)	471006	Robotic Surgical instruments
linear cutting stapler	Ezisurg Medical Co., Ltd.	U12M45	Surgical Stapler
Maryland bipolar forceps	Intuitive (Sunnyvale, CA)	471172	Robotic Surgical instruments
monopolar cautery hook	Intuitive (Sunnyvale, CA)	470483	Robotic Surgical instruments