Reverse Spatulated Hybrid Technique of Arterial Anastomosis in Kidney Transplant ()
1. Introduction
Kidney transplant is the treatment of choice for end-stage renal disease [1]. One of the critical aspects of a successful kidney transplant is vascular anastomosis, ensuring optimal perfusion of the graft while minimizing complications such as thrombosis, stenosis, or anastomotic leaks. Transplant surgeons use different techniques for arterial and venous anastomoses in the recipients. In 1902, Carrel described a 3-point anastomosis technique for allograft arterial anastomosis [2]. Since then, others have described variants using 2-point anastomosis, 1-knot techniques, 4-quadrant techniques, corner-saving techniques, nonsuture techniques, and other methods for vascular anastomoses in kidney transplant [3]-[7]. Most of these techniques were designed to reduce anastomotic and ischemic time while providing good patency, especially in the case of arterial anastomoses. The Reverse Spatulated Hybrid Technique (RSHT) is a vascular anastomosis approach developed at our center for living-donor kidney transplantation. It combines reverse spatulation to optimize luminal geometry with a hybrid suturing strategy designed to facilitate a controlled, wide anastomosis while maintaining a favorable graft lie. This study describes the RSHT and evaluates its clinical outcomes in renal transplantation.
2. Materials and Methods
A single-center observational retrospective study involving a dedicated transplant team. During the study period (October 2024 to February 2025), a total of 101 renal transplants were performed.
This is the standard technique followed by the team for an end-to-end anastomosis with the internal iliac artery since 2010, with over 3000 transplants done. This technique is not followed for end-to-side anastomosis.
2.1. Surgical Technique
Our transplant team consisted of two main surgeons, one working on donor nephrectomy and one on the recipient transplant procedure. The role was also reversed. Living donor nephrectomies were performed laparoscopically via the transperitoneal route and retroperitoneally for open. All the graft kidneys were placed retroperitoneally in the right iliac fossa. The kidney transplant procedure was performed by two surgeons, and both were experienced in the use of the reverse spatulated hybrid technique.
The reverse spatulated hybrid technique is a modification of the standard vascular anastomosis technique. Hybrid suturing in this context means that sutures can be either continuous or intermittent (interrupted). In our reverse spatulated hybrid technique (RSHT), a 3-point fixation is first created between the renal artery (RA) and the internal iliac artery (IIA); the posterior layer of the anastomosis is then sutured with a continuous stitch, and the anterior layer is completed with interrupted sutures. This configuration creates a wide anastomosis with all sutures placed under direct vision, and in our experience has been associated with an almost negligible incidence of transplant renal artery stenosis (1 case in more than 3000 transplants to date).
Skin preparation and side marking were performed on the morning of the surgery. After the patient was placed on the operating table, povidone iodine was used with a sponge for the first wash, and regular povidone iodine was used twice for the final preparation. The incision started 2 cm above the pubic symphysis and passes laterally and cranially along the edge of the rectus sheath, two finger breadths medial to the anterior superior iliac spine (Figure 1).
The confluence of the oblique abdominal muscles just lateral to the rectus sheath (the spigelian fascia) is divided to expose the peritoneum beneath [2]. After exposure of the transversalis fascia and peritoneum, the transversalis fascia is divided, and the peritoneum is reflected upward and medially to expose the psoas muscle and the iliac vessels. A self-retaining retractor is inserted, such as a Bookwalter, which has the advantage of providing good exposure while allowing the assistant to have both hands free to assist with the anastomosis. Lymphatics were ligated to expose the iliac vessels.
Figure 1. Skin incision and retroperitoneal approach for right iliac fossa kidney transplantation.
The internal iliac artery and external iliac vein were used as the first choice in vascular anastomoses. To prevent twisting or rotation, vessel clamps were used after confirming the exact length and position of the anastomotic site. The Bulldog clamp was preferred for the internal iliac artery. The internal iliac artery was divided and flushed with heparinized saline. For end-to-end anastomosis, an oblique incision on the recipient vessel and a reverse extension on the donor vessel (Figure 2(a) and Figure 2(b)).
(a) (b)
Figure 2. (a) Schematic representation of the graft kidney positioned in the right iliac fossa, showing the relationship between the renal artery and the internal iliac artery before arterial anastomosis; (b) Diagram illustrating the oblique arteriotomy on the internal iliac artery and the corresponding reverse spatulation of the graft renal artery used in the reverse spatulated hybrid technique.
The internal iliac artery is anastomosed end-to-end to the renal artery with 6-0 monofilament vascular suture in running fashion for the posterior layer and interrupted fashion for the anterior layer. Two-thirds of the artery diameter was measured with continuous sutures and one-third with interrupted sutures. The posterior layer started by placing sutures at 6 o’clock, and running suture performed till 10 o’clock with the short thread, stopped and locked by a new 6-0 Prolene. The needle was passed from inside to outside in the renal artery and from outside to inside in the host artery to prevent intimal separation. Posterior arterial anastomosis completed using the long thread till 2 o’clock, stopped and locked by using a piece of 6-0 Prolene (Figure 3, Figure 4(a) and Figure 4(b)).
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Figure 3. Schematic diagram of the reverse spatulated hybrid arterial anastomosis showing the three-point fixation and suture sequence from the 6 o’clock position, with continuous posterior suturing and anterior interrupted stitches between the 10 and 2 o’clock points.
Then, the anterior layer anastomosis was started from both corners and completed by 3 - 4 interrupted sutures using 6-0 Prolene. The advantage of this technique is that the whole procedure is done while the kidney is in its final position in the iliac fossa. Both posterior and anterior walls of the arterial anastomoses are done without handling the kidney.
The graft vein was anastomosed end-to-side to the recipient’s right external iliac vein using 6-0 Prolene in a continuous running fashion in posterior and anterior layers with fixation at 12 o’clock and 6 o’clock positions to prevent purse string effect. Ureterovesical anastomosis performed using a modified Lich-Gregoir technique in the anterior wall of the bladder over a 6/16 Fr DJ stent.
2.2. Data and Follow-Up
Intraoperative data, including the warm and cold ischemic times and arterial and venous anastomotic times, are recorded. Follow-up consists of color Doppler ultrasonographic examination of the anastomosis site on postoperative days 1 and 30, and measuring blood pressure and serum creatinine level daily until postoperative day 10; then, at 1, 3, 6, and 12 months after transplant, and then every 6 months if there is any clinical problem.
(a) (b)
Figure 4. (a) Intraoperative view of the renal graft in the right iliac fossa showing the completed reverse spatulated hybrid arterial anastomosis between the graft renal artery and the internal iliac artery; (b) Schematic view of the completed reverse spatulated hybrid arterial anastomosis between the graft renal artery and the internal iliac artery, illustrating the final wide, linear anastomotic lumen.
3. Results
A total of 86 kidney transplant recipients were included in the final analysis, based on predefined inclusion criteria.
Mean age of recipients was 36 ± 13.2 (9 - 66 years). 64 patients were male (74.42%), and 22 were female (25.58%).
82 (95.35%) of the donor nephrectomies were done laparoscopically and 4 (4.65%) by open surgery.
Mean kidney warm and cold ischemia time was 3.2 (1 - 8 minutes) and 75.2 (49 - 116 minutes).
Mean arterial and venous anastomotic time was 15.51 (9 - 32 minutes) and 12.38 (7 - 26 minutes).
All the graft renal arteries were anastomosed to the internal iliac artery, of which 84 (97.6%) were to the right and 2 (2.4%) to the left. All vein anastomosis was done to the external iliac vein.
No vascular complications were reported in the early postoperative period. Measuring the velocity of blood flow at the anastomotic sites by color Doppler ultrasonography on days 1, 4, and 30 after the transplant showed no evidence of arterial/ venous thrombosis or stenosis in any of the patients. During a mean follow-up of 2.5 (2 - 3 months), the mean serum creatinine level on the 1, 3, 30 and 60 - 90 days after the operation was 2.87 (0.5 - 9.2 mg/dL), 1.3 (0.5 - 3.8 mg/dL), 1.2 (0.5 - 4.4 mg/dL), 1.2 (0.5 - 4.6 mg/dL), respectively.
No delayed graft function was noted (defined as a persistence of a serum creatinine level of >4 mg/dL beyond the third day after transplant and necessity of at least one dialysis session within the 7 days post-transplant).
There were two mortalities; one case was attributed to septic shock secondary to left-sided cavitary pneumonia on POD-35, and the second case was due to cardiovascular failure on POD-136. Both had a functioning graft with maintained blood flows, proven by USG graft doppler done during their admission.
We did not encounter any vascular complications like renal artery/ vein thrombosis or stenosis. However, no contrast imaging was permissible because of the new kidney in place. The USG Doppler, as a noninvasive tool for documenting graft blood flow, is preferable.
4. Discussion
The introduction of the Carrel patch technique for end-to-end anastomosis of allograft arteries in 1902 marked a significant advancement in transplant surgery [2].
Many transplant surgeons presented their own technique for vascular anastomosis and made efforts to reduce ischemia time and risk of transplant artery stenosis, both of which can lead to allograft dysfunction [8]. Allograft arterial stenosis should be suspected in any recipient who presents with new onset or severe hypertension refractory to medical therapy, unexplained graft dysfunction, and a new audible bruit over the graft.
There are several techniques to do this anastomosis, and each one has its own merits and demerits. The type of anastomosis chosen by the surgeon depends on the mentor, the training received at their institution, and personal preference.
Since the RSHT used at our center is technically complex and associated with a longer learning curve than a conventional end-to-end anastomosis. This complexity is mainly related to two specific steps: the main point in RSHT is visualizing the lie of both the renal artery (RA) and the internal iliac artery (IIA), and precisely spatulating both vessels in reverse direction; lie and spatulation are visual assessments made beforehand and are the key learning steps in RSHT. The first suture is taken at the 6 o’clock position on both vessels, and the determination of this point and precise suturing is another key step. With both these maneuvers, we are able to create the widest possible anastomosis between RA and IIA and also to maintain the final lie of the graft without kinking the anastomosis. The skill is transferred by repeated exposure of the residents, fellows, and post-graduate students to the same technique being done by the same surgeon over and over again.
In the iliac fossa, the kidney is at a right angle to the iliac artery. As the graft kidney falls in the iliac fossa as its final resting place, the RSHT normalizes the kink formed with the arteries by reducing the angle and thus maintain a smooth linear direction with the anatomical direction of the internal iliac which is medio-obliquely. This approach minimizes turbulence, enhances endothelial alignment, and lowers the risk of vascular kinking, stenosis, or thrombosis, leading to improved graft perfusion and function. In our series, mean arterial anastomosis time was 15.5 minutes, which is within the range reported for conventional end-to-end anastomosis techniques in open and minimally invasive kidney transplantation, where arterial anastomosis times of roughly 12 - 20 minutes are commonly described.
From our observation, it has been shown that this alternative vascular anastomotic technique is safe, with a satisfactory outcome of kidney transplant compared to the conventional technique for a kidney transplant. We had no cases of vascular complications in the early postoperative period in our patients. We did not encounter any case of renal artery or venous thrombosis, or any allograft arterial stenosis. In the era of minimally invasive techniques, for kidney transplantation, including robotic-assisted kidney transplantation, the main challenge is to perform a quality vascular anastomosis in a restricted workspace. The same technique was performed by the same team in a minimally invasive approach. Our center has performed more than 3000 kidney transplants since 2010, and in this broader experience, the reverse spatulated hybrid technique has been associated with an extremely low incidence of clinically significant TRAS, supporting its patency and safety profile.
Zomorrodi et al. compared techniques 02 techniques. In 1 group, they used a 2-corner continuous suture technique, and in the other, they used a combined suture technique (two-thirds of the artery diameter with continuous suture and one-third with interrupted sutures). And they determined that factors like gentle tissue handling and adequate vessel diameter are more critical in preventing transplant artery stenosis than the suturing technique itself [9].
The majority of authors presented techniques’ variation according to the way of suturing (number of knots, corner saving), while others used clips and staplers. In 1996, Mital et al. performed arterial and venous anastomoses in kidney recipients using four stay sutures and vascular clips, completing each anastomosis in 8 minutes, and concluded that it is a safe, easy, and rapid method of renal vascular anastomosis. Jones further improved this by introducing a sutureless method with clips, reducing the ischemic period by 51% in comparison with the conventional running suture technique [10]. Ye et al. performed an end-to-end arterial anastomosis with titanium ring pin staplers in 36 kidney recipients [6].
Haberal et al. performed arterial anastomosis of transplanted kidneys in 183 recipients using a corner-saving approach. One patient had a renal arterial stenosis. The conclusion was that this approach lowers the incidence of vascular complications and is a simple and safe way to perform arterial anastomosis [4].
In 386 kidney patients, Simforoosh et al. reported the outcomes of vascular anastomosis using the 1-suture, 1-knot approach. No vascular complications were reported in the early postoperative period. The technique was safe, time-saving, and especially valuable in obese patients and recipients with deep iliac fossa [7].
In the minimally invasive era, and particularly in robot-assisted kidney transplantation (RAKT), the main technical challenge remains achieving a high-quality vascular anastomosis within a constrained workspace while limiting warm ischaemia. Large contemporary European experiences and comparative series suggest that RAKT can be performed safely with favourable graft outcomes in selected recipients, underscoring the need for standardised, reproducible anastomotic strategies that combine efficiency with precision [11] [12]. In addition, complex vascular anatomy is increasingly addressed in robotic programmes; ERUS data and subsequent comparative work indicate that RAKT using grafts with multiple vessels is feasible and often incorporates extracorporeal vascular reconstruction prior to implantation [13] [14].
The main limitation of the present study is its single-centre, retrospective observational design without a control group and with short follow-up. While a randomised trial would theoretically provide the highest level of evidence, such trials comparing surgical anastomotic techniques are unlikely to be feasible in routine transplantation; therefore, evidence will most realistically accumulate through comparative cohort studies and multicentre registries. Longer follow-up with standardised imaging surveillance is required to assess late events such as transplant renal artery stenosis, anastomotic aneurysm/pseudoaneurysm, and progressive intimal hyperplasia.
5. Conclusion
The RSHT offers optimal anastomotic geometry, reducing turbulence and optimizing vascular flow dynamics in renal transplantation. This technique, although complicated, will have a longer learning curve, but we feel this technique minimizes vascular complications and demonstrates excellent patency rates. This study is limited by its short duration and single-center design. Further multicentric studies with longer follow-up periods are warranted to more accurately evaluate the clinical relevance and long-term outcomes of the RSHT in renal transplantation.
Consent
This retrospective analysis used routinely collected clinical data that were anonymised prior to analysis. The work was conducted in accordance with institutional policies and the Declaration of Helsinki. Written informed consent was obtained for the publication of identifiable intraoperative images, where applicable.