Three‐dimensional virtual reconstruction guides robot‐assisted partial nephrectomy in a horseshoe kidney

Abstract

Horseshoe kidney is a renal fusion abnormality affecting 0.25–0.5% of the population [1]. Horseshoe kidneys demonstrate abnormal renal anatomy with atypical vasculature. These factors pose operative challenges and complicate tumour resection. Operative planning for robot-assisted partial nephrectomy (RAPN) in horseshoe kidneys is conventionally informed by CT imaging. However, the renal vasculature, tumour vasculature, and tumour involvement of the pelvicalyceal system are difficult to assess with two-dimensional (2D) images. Three-dimensional (3D) reconstructions more comprehensively display horseshoe kidney anatomy. 3D printing and 3D virtual remodelling are used in a number of surgical cases [2]. Compared with 2D imaging, 3D reconstructions improve subjective knowledge of case-specific anatomy, increase surgeons’ confidence, and improve surgical plans [3]. A 3D virtual reconstruction is an accessible and inexpensive tool to apply to surgical planning in horseshoe kidney RAPN. This step-by-step guide describes the use of 3D virtual anatomical modelling to inform surgical approach, guide intraoperative decisions, and predict and plan for potential complications. A 74-year-old male presented with an incidental ultrasound finding of a 45 mm left complex cystic lesion in a horseshoe kidney. Contrast CT of the renal tract demonstrated a 35 × 26 mm partially endophytic complex cyst arising from the left upper pole of the horseshoe kidney. A staging CT of the chest, abdomen, and pelvis did not reveal evidence of metastatic disease. Surgical excision was recommended and a left horseshoe kidney RAPN was performed with the da Vinci® Surgical System (Intuitive Surgical, Sunnyvale, CA, USA). A contrast CT of the renal tract was performed with pre, arterial, and portal phase images. The 3D virtual reconstruction of the horseshoe kidney was generated from high-resolution CT images (Fig. 1). The reconstruction provided a 360° view of the horseshoe kidney and detailed the size and location of the complex cyst, its vascular anatomy, and its relationship to the renal pelvis and surrounding structures. As expected in a horseshoe kidney, the vasculature was atypical. Two renal arteries and one renal vein dividing proximally were identified as contributing to the vasculature of the lesion. The 3D reconstruction also outlined the vascular supply of the isthmus and right side of the horseshoe kidney arising from aorta inferior to the inferior mesenteric artery. This information enabled planning for secondary and tertiary manoeuvres in the event of bleeding. The patient was positioned in the right lateral decubitus position with pressure area care. An open Hasson technique was utilised to insert a camera port 3-cm cranial to the umbilicus at the lateral rectus muscle border. Three further robotic instrument ports, one assistant port, and one AirSeal port were inserted linearly at the lateral border of rectus. The cannulae were docked, and instruments placed. The descending colon was mobilised along the white line of Toldt to expose the left upper pole of the horseshoe kidney. The spleen was medialised and psoas major muscle identified as an anatomical landmark. Gerota's fascia was entered medially to begin dissection. The 3D reconstruction was consulted intraoperatively to assist with identifying the course of the left renal vessels. The 3D reconstruction guided the dissection and mobilisation of the left renal arteries and vein (Fig. 2). Defatting of the left kidney assisted dissection. The renal isthmus was dissected as a safety measure in preparation for conversion to heminephrectomy in the event of substantial haemorrhage. The left renal vessels were isolated and slung with vessel loops. Ultrasound defined the lesion boundaries. Scanlan® RELIANCE bulldog clamps (Scanlan International Inc., St Paul, MN, USA) were applied to the left renal arteries and vein. The tumour was excised with macroscopically clear margins. A small side branch venotomy p