Transmesenteric Laparoscopic Pyeloplasty in Trendelenburg Position for Horseshoe Kidney with Hydronephrosis

Summary

In this report, we present a case of intraperitoneal laparoscopic surgery in the Trendelenburg position (ILSTP) for trans mesenteric pyeloplasty in a horseshoe kidney with hydronephrosis. We provide a detailed protocol and practical tips for surgeons interested in adopting this approach.

Abstract

Due to anomalous anatomy, pyeloplasty with a horseshoe kidney (HSK) presents a technical challenge. Previously, we reported a technique of intraperitoneal laparoscopic surgery in Trendelenburg position (ILSTP) for pyelolithotomy, pyeloplasty, and heminephrectomy in patients with HSKs. To demonstrate the procedure, the case of a 29-year-old female with HSK and left hydronephrosis who underwent pyeloplasty using transmesenteric ILSTP is presented. Magnetic resonance confirmed HSK with left-sided hydronephrosis. After opening a window in the mesentery and dissecting the renal pelvis and left ureter, a crossing vein causing ureteropelvic junction obstruction (UPJO) was identified and ligated, followed by non-dismembered pyeloplasty. The operative time was 147 min with blood loss of 5 mL. Follow-up evaluation at 8 weeks post-stent removal demonstrated significant resolution of hydronephrosis without complications. This study describes the feasible use of the transmesenteric ILSTP technique, providing an important method to perform pyeloplasty in selected HSK patients. This technique requires surgeons to possess advanced laparoscopic skills, and the method may face limitations depending on the thickness of the mesentery.

Introduction

Horseshoe kidney (HSK) is a prevalent congenital renal anomaly characterized by midline fusion of the lower poles of both kidneys¹. The incidence is about 1:500 in the general population, with a male predominance of 2:1². One of its main characteristics is several anatomical variations, which may promote nephrolithiasis, ureteropelvic junction obstruction, hydronephrosis, vesicoureteral reflux, and pyelonephritis^3,4. Hydronephrosis occurs in 30% of HSK patients⁵, who normally have abnormally high insertion of ureters, ureters traversing the isthmus, or aberrant vessels⁶. Many of these complex anatomical anomalies require surgical intervention.

Currently, pyeloplasty has gained momentum for the treatment of hydronephrosis over the last decade⁷. However, it can be challenging to create and maintain an appropriate and safe surgical view in patients with HSK in traditional laparoscopy due to the abnormal structure of the kidney. Besides, dissecting the isthmus is difficult as it can bleed heavily, or the opposite kidney can be injured⁸. Various minimally invasive techniques have been suggested, with reported success rates broadly ranging from 55% to 80%⁹. Previously, the authors used the intraperitoneal laparoscopic surgery in Trendelenburg position (ILSTP) for pyeloplasty in patients with HSKs.

In comparison to traditional laparoscopy with flank position, our approach offers an appropriate and safe surgical view¹⁰. This report introduces a transmesenteric ILSTP approach for pyeloplasty, The overall goal of this method is to offer a direct path to the renal pelvis with less tissue dissection and bowel manipulation^11,12. Transmesenteric ILSTP may represent an interesting and advantageous technical improvement of ILSTP in HSK patients, and it is suitable for patients with left-sided UPJO and those with thin mesentery. This approach can be an alternative HSK pyeloplasty approach compared to the standard laparoscopic approach. ILSTP provides intuitive insight into the operative field, increases feasibility for the dissection and suturing

Case presentation:

A 29-year-old woman was incidentally diagnosed with left hydronephrosis on ultrasonography and visited our institution. She was mostly asymptomatic but noticed discomfort in her left lower back. Magnetic Resonance revealed HSK and left severe hydronephrosis without ureteral dilation. In addition, the left UPJ was suspected to be obstructed (Figure 1). She had no history of strong left abdominal pain or urinary tract infection. She also had no known congenital anomalies. Blood chemistry examination revealed no renal dysfunction or other abnormal findings. Her serum creatinine was 97 mmol/L, and glomerular filtration rate (GFR) was 18 mL/min/1.73 m².

Diagnosis, assessment, and plan:
The initial ultrasonography was performed as part of a routine health checkup, which incidentally revealed hydronephrosis. This finding warranted further investigation with magnetic resonance imaging (MRI) to better characterize the kidney anatomy and determine the cause of hydronephrosis. MRI was chosen over computed tomography (CT) to avoid radiation exposure in this young patient while providing excellent soft tissue detail. The MRI confirmed the diagnosis of horseshoe kidney with severe left-sided hydronephrosis without ureteral dilation, strongly suggesting ureteropelvic junction (UPJ) obstruction as the primary pathology.

The diagnosis of horseshoe kidney with left UPJ obstruction was based on the characteristic anatomical findings on MRI, including the fusion of the lower poles of both kidneys and the dilatation of the left renal pelvis without distal ureteral involvement. Differential diagnoses considered included nephrolithiasis, congenital ureteral stricture, crossing vessels, and other less common causes of UPJ obstruction. The presence of mild but persistent lower back discomfort correlated with the imaging findings, supporting the diagnosis of symptomatic UPJ obstruction.

Preoperative laboratory tests, including complete blood count, comprehensive metabolic panel, and urinalysis, were performed to assess renal function and exclude urinary tract infection. These investigations showed normal renal function despite the significant hydronephrosis, likely due to the compensatory function of the right kidney. Nuclear renal scan was not performed as the diagnosis was clear on MRI, and the symptomatic nature of the condition warranted surgical intervention regardless of split renal function.

After a comprehensive assessment, laparoscopic pyeloplasty using a transmesenteric approach in the Trendelenburg position was planned as the most appropriate treatment. This surgical approach was selected for several reasons: (1) the patient's anatomy with a horseshoe kidney made traditional approaches challenging, (2) the transmesenteric route would provide direct access to the left UPJ with minimal bowel manipulation, and (3) the Trendelenburg position would offer better visualization of the operative field. The goal of surgery was to relieve the UPJ obstruction, preserve renal function, and alleviate the patient's symptoms. Potential complications of the procedure included bleeding, infection, anastomotic leak, recurrent obstruction, and injury to adjacent structures, all of which were discussed with the patient before obtaining informed consent.

Protocol

The procedure was performed in accordance with the ethical standards for patient care of South China Hospital of Shenzhen University, and with the patient's informed consent. Ethical approval was obtained under approval number: 2022-0117.

1. Preoperative procedure

1. The patient's personal or familial history of horseshoe kidney or compatible symptoms was collected.
2. Routine blood tests, electrocardiogram (ECG), chest CT, urinalysis, and other relevant examinations were performed preoperatively.
3. The patient received a prophylactic intravenous infusion of cefuroxime sodium 30 min prior to surgery.

2. Surgical procedure

1. General anesthesia with tracheal intubation, intravenous, and inhalational agents was administered. The patient was positioned in a 30° Trendelenburg position with their head down, see Figure 2. The primary surgeon and assistant stand on the patient's right side, and the scrub nurse stands on the left side.
   NOTE: The Trendelenburg position facilitates the cephalad displacement of the intestines, thereby improving intraoperative exposure and minimizing bowel interference during the procedure¹³.
2. A 2 cm infraumbilical incision was made using a scalpel, and a 10 mm blunt trocar was introduced under direct visualization to enter the abdominal cavity using the Hasson technique.
3. Pneumoperitoneum was achieved by carbon dioxide (CO₂) insufflation until the intraabdominal pressure reached 12-14 mmHg. A 30° laparoscope was inserted into the 10 mm infraumbilically placed port.
4. Under direct visualization, the two other trocars were placed at the iliac crest level at 6 cm right (12 mm) and left (5 mm) to the camera port. Another 12 mm trocar was placed adjacent to the umbilicus (see Figure 2).
   1. In patients with short pubis to umbilicus distance, the umbilicus port was placed first to provide direct vision while placing the infraumbilical port, which may minimize the risk of bladder injury.
5. A full abdominal inspection using laparoscopy was performed to observe the location of retroperitoneal organs and the thickness of mesenteric fat, assessing the feasibility of transmesenteric surgery.
6. A 3-4 cm longitudinal incision was made through the mesentery of the descending colon in order to create an opening, avoiding injuring the blood vessels and intestine. The incision was made directly over the pelvis using the ultrasonic scalpel (see Figure 3A).
7. The mesenteric fascia was dissected, and the renal pelvis and left ureter were exposed. The ascending portion of the duodenum along the dissection plane was visualized (see Figure 3B).
8. After mobilization of the ureteropelvic region, we identified a crossing branch of the genital gland vein as the main reason for UPJ obstruction. After confirming that it is a vein, ligate it. In cases where UPJO is caused by ectopic artery compression, transposition of the crossing artery and dismembered pyeloplasty are needed (see Figure 3C, D).
9. A non-dismembered pyeloplasty was performed, and the renal pelvis was meticulously reconstructed as described below (see Figure 3E,F).
   1. A longitudinal incision was made from the lateral aspect of the proximal ureter to the renal pelvis, measuring approximately 3-4 cm using laparoscopic scissors. The posterior walls of the ureter and pelvis were anastomosed using a 4-0 absorbable running suture.
   2. A guide wire was then passed through the proximal ureter into the bladder, and a 4.7 Fr Double-J stent was passed over the guide wire into the bladder. Then the proximal end of the Double-J stent was placed within the renal pelvis.
   3. The anterior aspect of the anastomosis is completed with a suture of the proximal pelvis and ureter. The ureteropelvic anastomosis was performed using 4-0 polyglactin sutures on a half-circle, round-bodied needle.
10. The mesenteric incision was closed with running 4-0 polyglactin absorbable sutures. Careful inspection of the surgical field for active bleeding, urine leaks, and gastrointestinal injuries was done.
11. A drainage tube was placed adjacent to the mesenteric window. It was ensured that the drain makes no direct contact with the anastomosis. The peritoneum and fascia were closed with continuous sutures using 3-0 absorbable material, and the skin was closed with interrupted sutures using 4-0 absorbable material.

3. Postoperative care

1. The patient was given second-generation cephalosporin treatment according to the guidelines within 24 h after surgery.
2. Intravenous opioids, non-opioid analgesics, and patient-controlled analgesia were administered. A liquid diet and bedside activity were started at 6 h postoperatively. The oral analgesics were taken until the patient was fully tolerant without the sudden onset of severe pain¹⁴ .
3. The drainage tube was removed 3-4 days after the operation, depending on the drainage volume.

Results

We have adopted the innovative technique of ILSTP since 2021. This surgery progressed smoothly, and there were no intraoperative or postoperative complications. The operation lasted 147 min, and the intraoperative blood loss was 5 mL. The enhanced recovery after surgery (ERAS) pathway was used during the postoperative recovery period in the surgical ward. Postoperative flatus was observed 12 h after surgery. The postoperative hospital stay was 4 days. The Double-J stent was removed 8 weeks after the operation, and urinar...

Discussion

Horseshoe kidney is a common congenital renal malformation, which usually occurs when two kidneys fuse and disrupt the arrangement of blood vessels¹⁵. About 2/3^rd of all HSK cases have vascular anomalies, which possibly result in UPJO of various degrees¹⁶. In clinical work, the management of crossing vessels has always been a difficult challenge. Crossing arteries were normally retained as far as possible, as they can provide a part of the blood supply to the kid...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Double J ureteral stent	USI-526-CE-B	Cook Group Inc. (Bloomington, IN, USA)
Endoscopic Imaging System	TUGE 4K 3D ICG Three-in-One Endoscopic Imaging System	Tuge Medical Technology Co., Ltd. (Nanjing, China)