Abudu Olalekan Abdul-Rafiu, Ogunjimi Moses Adebisi, Ojewola Rufus Wale, Arogundade Rasheed Ajani
Department of Imaging, University Hospital Ayr, NHS Ayrshire and Arran, Kilmarnock, UK.
Urology Division, Department of Surgery, Lagos University Teaching Hospital, Lagos, Nigeria.
J West Afr Coll Surg. 2025 Jul-Sep;15(3):344-349. doi: 10.4103/jwas.jwas_64_24. Epub 2025 Feb 4.
The nutcracker phenomenon (NCP) is a rare and often unrecognised cause of varicocele, haematuria, and chronic pelvic pain due to the left renal vein (LRV) compression between the aorta and the superior mesenteric artery (anterior nutcracker). Its varied clinical manifestations make the diagnosis difficult and usually delayed. A high index of clinical suspicion, with appropriate imaging studies is crucial for the diagnosis.
We used a colour Doppler ultrasound scan to investigate the anatomic and haemodynamic properties of testicular and renal venous drainage. The emphasis was to determine the presence or absence of NCP, its possible effects on varicocele formation and severity, and its relationship with the body mass index (BMI) of the subjects.
We carried out Doppler scrotal and upper abdominal ultrasound examinations of 100 subjects with male infertility and clinical varicoceles (group A), and 100 controls with male infertility but without varicoceles (group B). The mean peak velocity (PV) and the anteroposterior (AP) diameters of different segments of the renal veins, as well as the diameters of the testicular veins of the subjects in the two groups were measured and compared. The ratios of the PV and the diameters between the hilar portion and the aorto-mesenteric portion of the LRV were also calculated and compared. A PV ratio or anteroposterior diameter ratio between the two portions greater or equal to 5.0 was considered diagnostic of NCP. The diagnosis of varicocele was confirmed by visualising a dilated pampiniform plexus vein measuring greater than 2 mm in diameter using an ultrasound scan.
Six out of 100 subjects in group A had diameter and PV ratios (≥5.0) in the LRV that suggested the presence of NCP, and all participants in group B had neither diameter nor PV ratio suggestive of NCP. The prevalence of NCP seen within the varicocele group in this study was statistically significant ( = 0.038). Five (83.3%) of the six subjects in the NCP-associated varicocele subgroup had microscopic haematuria, orthostatic proteinuria, or both; these qualified them for the diagnosis of nutcracker syndrome (NCS), A significantly lower mean BMI ( = 0.004) was noted among the NCP-associated varicocele subgroup compared to those without NCP.
Our findings indicate that the NCP is a significant finding in patients with varicoceles in our environment, and it is more common with lower BMI.
胡桃夹现象（NCP）是精索静脉曲张、血尿和慢性盆腔疼痛的一种罕见且常未被认识的病因，是由于左肾静脉（LRV）在腹主动脉和肠系膜上动脉之间受压（前胡桃夹）所致。其多样的临床表现使得诊断困难且通常延迟。高度的临床怀疑以及恰当的影像学检查对诊断至关重要。
我们使用彩色多普勒超声扫描来研究睾丸和肾静脉引流的解剖及血流动力学特性。重点是确定是否存在NCP，其对精索静脉曲张形成和严重程度的可能影响，以及它与受试者体重指数（BMI）的关系。
我们对100例患有男性不育症且有临床精索静脉曲张的受试者（A组）以及100例患有男性不育症但无精索静脉曲张的对照者（B组）进行了阴囊和上腹部多普勒超声检查。测量并比较了两组受试者肾静脉不同节段的平均峰值流速（PV）和前后径（AP），以及睾丸静脉的直径。还计算并比较了LRV肾门部与腹主动脉 - 肠系膜部之间的PV比值和直径比值。两部分之间的PV比值或前后径比值大于或等于5.0被认为可诊断为NCP。通过超声扫描显示直径大于2mm的扩张蔓状静脉丛来确诊精索静脉曲张。
A组100例受试者中有6例LRV的直径和PV比值（≥5.0）提示存在NCP，而B组所有参与者的直径和PV比值均未提示NCP。本研究中精索静脉曲张组内NCP的患病率具有统计学意义（ = 0.038）。NCP相关精索静脉曲张亚组的6例受试者中有5例（83.3%）有镜下血尿、体位性蛋白尿或两者皆有；这些符合胡桃夹综合征（NCS）的诊断标准。与无NCP者相比，NCP相关精索静脉曲张亚组的平均BMI显著更低（ = 0.004）。
我们的研究结果表明，在我们所处环境中，NCP在精索静脉曲张患者中是一个重要发现，且在BMI较低者中更常见。
