KIDNEY TRANSPLANT APPROACHES: COMPARING EXTRAPERITONEAL AND INTRAPERITONEAL METHODS

Kidney transplantation is a complex and life-saving surgical procedure requiring meticulous planning and execution. A critical decision involves the surgical approach used to place the donor kidney (graft) within the recipient’s body and connect it to the blood vessels and urinary tract. While variations exist based on individual patient anatomy and surgical team preference, the primary distinction lies in whether the graft is placed in an extraperitoneal or intraperitoneal location. This document outlines these approaches, their characteristics, and factors influencing their selection.

Key Concepts:

1. The Peritoneum: This is a serous membrane that lines the abdominal cavity (parietal peritoneum) and covers most of the abdominal organs (visceral peritoneum). It creates the peritoneal cavity, which contains structures like the stomach, intestines, liver, and spleen.
2. Extraperitoneal Space: This is the space outside the peritoneal cavity. Structures here are retroperitoneal (behind the peritoneum, like the native kidneys, aorta, vena cava) or subperitoneal (below the peritoneum, like the bladder and lower pelvic structures). The iliac fossa, a common site for kidney transplantation, is within the extraperitoneal space.
3. Intraperitoneal Space: This is the potential space within the peritoneal cavity, enclosed by the peritoneum.

The Two Primary Recipient Surgical Approaches:

The goal is to place the donor kidney in a location where its vessels can be easily and safely connected to large recipient vessels, and its ureter can be connected to the bladder. The most common site in adults is the iliac fossa.

1. The Extraperitoneal Iliac Fossa Approach

This is the standard and most widely used approach for kidney transplantation in adult recipients.

• Location and Incision:
  • The graft is typically placed in the il extraperitoneal space within the right or left iliac fossa (the lower outer part of the abdomen, within the pelvis).
  • A curvilinear incision, often called a “hockey-stick” or Gibson incision, is made in the lower abdomen, usually on the side chosen for the transplant (most commonly the right side). This incision extends from just above the anterior superior iliac spine down towards the pubic bone, following the curve of the groin crease.
  • Alternatively, a straight oblique incision can be used in the same region.
• Accessing the Extraperitoneal Space:
  • The surgeon carefully dissects through the layers of the abdominal wall musculature (external oblique, internal oblique, transversus abdominis).
  • The peritoneum, which lines the inner abdominal wall, is identified and meticulously pushed medially (towards the midline) and superiorly (upwards). This creates a working space outside the peritoneal cavity but within the bony confines of the pelvis – the extraperitoneal iliac fossa.
• Vascular Anastomoses:
  • The recipient’s external iliac artery and external iliac vein (or sometimes common iliac vessels) are identified within the extraperitoneal space. These are large blood vessels that are readily accessible in this location and provide excellent blood flow.
  • The renal artery of the donor kidney is typically connected (anastomosed) end-to-side to the recipient’s external iliac artery.
  • The renal vein of the donor kidney is typically connected end-to-side to the recipient’s external iliac vein.
• Ureteral Anastomosis (Ureteroneocystostomy):
  • The donor ureter (the tube draining urine from the kidney) is brought down to the recipient’s bladder, which is located in the subperitoneal space (part of the extraperitoneal region).
  • A connection is made between the donor ureter and the recipient bladder. The most common technique involves creating a tunnel within the bladder wall (extravesical technique, like the Lich-Gregoir method) or directly implanting the ureter into the bladder after opening it (intravesical technique, like the Leadbetter-Politano method, though less common now). The goal is to create a non-refluxing connection to prevent urine from flowing back up to the kidney.
• Advantages of the Extraperitoneal Approach:
  • Reduced Risk of Bowel Injury: Working outside the peritoneal cavity significantly minimizes the risk of damaging the intestines during dissection or retraction.
  • Lower Incidence of Post-Operative Ileus: Because the bowel is not manipulated as extensively (or at all) compared to an intraperitoneal approach, the period of post-operative bowel inactivity (ileus) is typically shorter and less severe.
  • Containment of Complications: Should complications like bleeding, infection, or urine leaks occur, they tend to be localized within the extraperitoneal space rather than spreading throughout the entire peritoneal cavity, which can lead to peritonitis – a more severe and widespread infection.
  • Familiarity: This approach is the standard and most familiar to transplant surgeons, leading to a high level of expertise.
  • Accessibility of Vessels: The iliac vessels provide reliable and robust access for vascular connections in most adults.
• Potential Disadvantages of the Extraperitoneal Approach:
  • Limited Space: In some patients (e.g., those with a narrow pelvis, significant obesity, or prior surgeries/radiation in the area), the extraperitoneal space in the iliac fossa can be relatively confined, making surgical maneuvers more challenging.
  • Nerve Injury Risk: Nerves running through the pelvic region, such as the ilioinguinal and iliohypogastric nerves, are in proximity to the incision and dissection area. There is a small risk of stretching or transecting these nerves, leading to numbness or pain in the groin or thigh.
  • Lymphocele Formation: Disruption of lymphatic vessels in the iliac fossa can lead to the accumulation of lymphatic fluid (lymphocele), though this can occur with either approach.

2. The Intraperitoneal Approach

This approach involves placing the kidney graft inside the peritoneal cavity. While not the standard for routine adult kidney-only transplants, it is used in specific circumstances.

• Location and Incision:
  • The graft can be placed in various locations within the peritoneal cavity, depending on the context. Common sites include the upper abdomen or pelvis.
  • Access is gained via a laparotomy incision, often a midline incision or a large transverse incision, allowing wide access to the abdominal cavity.
• Accessing the Intraperitoneal Space:
  • The surgeon incises the peritoneum and enters the abdominal cavity directly.
  • Intra-abdominal organs (intestines, etc.) are carefully retracted to expose the desired recipient vessels.
• Vascular Anastomoses:
  • Vessels used can vary. For a standard kidney placement within the peritoneal cavity, the iliac vessels might still be used, accessed from within.
  • In specific situations, larger vessels like the aorta and inferior vena cava might be utilized, particularly in pediatric transplants or multi-organ transplants where other vessels are involved.
  • The vascular connections (renal artery to recipient artery, renal vein to recipient vein) are performed similar to the extraperitoneal approach, but within the confines of the peritoneal cavity.
• Ureteral Anastomosis:
  • The ureter is connected to the bladder, similar to the extraperitoneal approach. The bladder is accessed from within the peritoneal cavity or by extending dissection subperitoneally.
• Specific Indications for the Intraperitoneal Approach:
  • Pediatric Transplantation: In very young or small children, the iliac fossa may be too small to accommodate an adult donor kidney. The larger abdominal cavity provides more space, and the aorta and vena cava offer larger caliber vessels for connection.
  • Simultaneous Pancreas-Kidney Transplant (SPK): When transplanting both a kidney and a pancreas, both organs are typically placed within the peritoneal cavity, often in different locations, using a large incision. The pancreas is usually placed on the right side, and the kidney on the left, or vice versa.
  • Previous Extensive Pelvic Surgery/Radiation: If the iliac fossae are significantly scarred, distorted, or have compromised vessels due to prior operations (e.g., multiple hernia repairs, vascular surgery, prostatectomy) or radiation therapy, the iliac fossa approach may be technically challenging or unsafe. An intraperitoneal approach may allow access to healthier vessels or a less scarred recipient site elsewhere in the abdomen.
  • Multiple Transplants: In patients receiving a second or subsequent kidney transplant, the preferred iliac fossa may have been used previously. An intraperitoneal approach might be necessary to find a suitable vascular supply and placement site.
  • Combined Procedures: If another intra-abdominal procedure is necessary at the time of transplant, an intraperitoneal approach allows for both.
• Potential Disadvantages of the Intraperitoneal Approach:
  • Increased Risk of Bowel Injury: Direct manipulation and retraction of the intestines within the peritoneal cavity inherently carries a higher risk of accidental injury (perforation, serosal tears).
  • Higher Risk of Post-Operative Ileus: Handling the bowel leads to a greater likelihood and severity of prolonged bowel inactivity after surgery.
  • Risk of Peritonitis: If a vascular or ureteral leak occurs within the peritoneal cavity, it can lead to widespread contamination and peritonitis, a potentially life-threatening infection.
  • Adhesion Formation: Surgery within the peritoneal cavity carries a risk of developing post-operative adhesions between organs and the abdominal wall, which can cause chronic pain or future bowel obstruction.
  • Less Containment: Bleeding or infection is less likely to be localized compared to the extraperitoneal space.

Factors Influencing the Choice of Approach:

The decision between an extraperitoneal and intraperitoneal approach is made based on a careful assessment of the recipient’s individual circumstances:

• Recipient Age and Size: Pediatric recipients often require an intraperitoneal approach due to pelvic size limitations.
• Prior Surgical History: Previous abdominal or pelvic surgeries (especially vascular, colorectal, gynecological, or multiple hernia repairs) can cause scarring and adhesions that may make the standard extraperitoneal approach difficult or hazardous, potentially necessitating an intraperitoneal approach or careful adaptation of the technique.
• Recipient Vascular Anatomy and Health: The condition, size, and location of the recipient’s vessels (iliac, aorta, vena cava) influence the choice of vascular connections and thus potentially the surgical approach required to access them safely. Significant atherosclerosis or prior vascular grafts can be factors.
• Type of Transplant: Simultaneous organ transplants (like SPK) almost always require an intraperitoneal approach.
• Recipient Body Habitus: Extreme obesity can sometimes make access and dissection in the iliac fossa more challenging, though it doesn’t automatically preclude the extraperitoneal approach.
• Presence of Abdominal Conditions: Conditions like large hernias, ascites, or significant intra-abdominal pathology can influence the preferred site and approach.
• Surgeon Experience and Preference: While guidelines exist, the surgical team’s expertise and comfort level with a particular approach in a given complex scenario play a role.

General Surgical Steps (Common Elements):

Regardless of the approach, several key stages are involved in recipient surgery:

1. Incision and Access: Creating the surgical opening and gaining access to the chosen space (extraperitoneal or intraperitoneal).
2. Vessel Exposure and Preparation: Identifying and carefully preparing the recipient artery and vein for connection. This involves dissecting around the vessels and temporarily clamping them.
3. Graft Preparation: The donor kidney is brought into the sterile field, and its renal artery and vein are prepared for anastomosis.
4. Vascular Anastomoses: Connecting the donor kidney’s vein to the recipient vein and the donor artery to the recipient artery. Blood flow is then restored to the graft.
5. Graft Perfusion and Assessment: Observing the kidney for signs of healthy blood flow (color change, firmness, potentially urine production).
6. Ureteral Anastomosis: Connecting the donor ureter to the recipient bladder or urinary tract.
7. Hemostasis and Drainage: Ensuring all bleeding is controlled and potentially placing surgical drains to remove excess fluid.
8. Closure: Closing the surgical incision layer by layer.

Conclusion:

The surgical approach to kidney transplantation is a critical determinant of procedural safety and potential post-operative outcomes. The extraperitoneal iliac fossa approach is the standard for most adult single-kidney transplants due to its advantages in minimizing bowel-related risks and localizing potential complications. The intraperitoneal approach, while carrying higher risks related to bowel manipulation and peritonitis, is essential and sometimes necessary for specific patient populations (e.g., pediatrics) or complex transplant scenarios (e.g., SPK, challenging anatomy). The choice of approach is a carefully considered decision made by the transplant surgical team based on the recipient’s unique clinical profile and the specific requirements of the transplant procedure.