Shah Hardik U, Ojili Vijayanadh
Department of Body Imaging, University of Texas Health Science Center, San Antonio, Texas, USA.
Indian J Radiol Imaging. 2017 Apr-Jun;27(2):133-140. doi: 10.4103/ijri.IJRI_298_16.
Horseshoe kidney is the most common congenital renal fusion anomaly with an incidence of 1 in 400-600 individuals. The most common type is fusion at the lower poles seen in greater than 90% of the cases, with the rest depicting fusion at the upper poles, resulting in an inverted horseshoe kidney. Embryologically, there are two theories hypothesizing the genesis of horseshoe kidney - mechanical fusion theory and teratogenic event theory. As an entity, horseshoe kidney is an association of two anatomic anomalies, namely, ectopia and malrotation. It is also associated with other anomalies including vascular, calyceal, and ureteral anomalies. Horseshoe kidney is prone to a number of complications due to its abnormal position as well as due to associated vascular and ureteral anomalies. Complications associated with horseshoe kidney include pelviureteric junction obstruction, renal stones, infection, tumors, and trauma. It can also be associated with abnormalities of cardiovascular, central nervous, musculoskeletal and genitourinary systems, as well as chromosomal abnormalities. Conventional imaging modalities (plain films, intravenous urogram) as well as advanced cross-sectional imaging modalities (ultrasound, computed tomography, and magnetic resonance imaging) play an important role in the evaluation of horseshoe kidney. This article briefly describes the embryology and anatomy of the horseshoe kidney, enumerates appropriate imaging modalities used for its evaluation, and reviews cross-sectional imaging features of associated complications.
马蹄肾是最常见的先天性肾融合异常，发病率为400 - 600人中1例。最常见的类型是下极融合，见于超过90%的病例，其余表现为上极融合，形成倒马蹄肾。胚胎学上，有两种理论假设马蹄肾的发生——机械融合理论和致畸事件理论。作为一个实体，马蹄肾是两种解剖学异常的联合，即异位和旋转不良。它还与其他异常有关，包括血管、肾盏和输尿管异常。马蹄肾因其异常位置以及相关的血管和输尿管异常而容易发生多种并发症。与马蹄肾相关的并发症包括肾盂输尿管连接处梗阻、肾结石、感染、肿瘤和创伤。它还可能与心血管、中枢神经、肌肉骨骼和泌尿生殖系统异常以及染色体异常有关。传统成像方式（平片、静脉肾盂造影）以及先进的断层成像方式（超声、计算机断层扫描和磁共振成像）在马蹄肾的评估中发挥着重要作用。本文简要描述了马蹄肾的胚胎学和解剖学，列举了用于其评估的合适成像方式，并综述了相关并发症的断层成像特征。
