Chronic abdominal pain and haematuria in internal medicine: do not forget about the Nutcracker syndrome.

Abstract

A 54-year-old woman was referred to our internal medicine department because of chronic abdominal pain and microscopic haematuria. She complained of a mild, tolerable but persistent low abdominal and pelvic pain, which did not have any relationship with food intake, body position or bowel function. Such symptoms started when she was 20, but previous clinical and diagnostic evaluations resulted inconclusive despite the several diagnoses hypothesized and tested (irritable bowel disease, diverticular disease, urinary tract infections, pelvic inflammatory disease and conversion disorder). All the attempted treatments (among which, proton-pump inhibitors and antidepressant drugs) did not translate into a significant clinical improvement. After several years, low back pain with inflammatory features and lumbar spine stiffness appeared. Blood tests showed CRP and ESR increase. Rheumatoid factor, anti-citrullinated-peptide and antinuclear antibodies were negative, HLA-B27 antigen was positive. A lumbo-sacral spine X-ray suggested bilateral sacro-ileitis, allowing to put a diagnosis of ankylosing spondylitis. NSAIDs were used as first-line agents for about 1 year but subsequently, for the worsening of articular symptoms, TNF-α antagonists were started. Such a diagnosis could have explained abdominal pain and haematuria, however, during the following 9 years, abdominal pain and microscopic haematuria persisted. In the suspect of a chronic inflammatory bowel disease, she underwent to multiple endoscopic examinations: gastroscopies revealed chronic helicobacter pylori-negative gastritis, while colonoscopies did not show any abnormality. Fifteen abdominal ultrasound examinations, annual gynaecological visits, six urine coltures and periodic autoantibodies determination resulted normal. In the days before our evaluation, the gastroenterologist suggested symptomatic therapy for a suspect irritable bowel disease and, to better investigate the chronic haematuria, the nephrologist recommended a renal biopsy, which the patient refused. When admitted to our department, the subject’s general conditions were good. Blood pressure, heart rate and oxygen saturation were normal. Abdominal and cardiopulmonary examinations were unremarkable, with no abdominal bruits. Articular symptoms were well-controlled by the anti-TNFα treatment. Blood count, hepato-renal function, ESR, CRP and serum electrophoresis were normal. Urinary sediment showed several erythrocytes without cylinders, leukocytes, proteins or bacteria. In absence of suggestive clinical or laboratoristic signs, we completed our physical examination with a focused abdominal ultrasound evaluation. We did not find any pathological findings in the liver, spleen, biliary tract and pancreas; both kidneys were morphologically normal; there were no pelvic masses and the intestinal loops showed no detectable alterations; the abdominal tract of the aorta and visceral arteries, including the celiac tripod, mesenteric arteries and renal arteries appeared regular, with no evidence of vascular stenoses; portal cavernoma, a potential cause of chronic abdominal pain, was excluded; no signs of thrombosis were found in the renal veins, but we observed a severe dilatation of the left renal vein (LRV) (Fig. 1) with a LRV compression in a markedly reduced (8 mm) aortomesenteric space. The Doppler evaluation revealed an increase in flow velocity in the narrowed tract of the vessel and a reduction before the compression. Our patient had chronic haematuria, abdominal pain and ultrasonographic evidence of LRV obstruction associated to aortomesenteric compression, which were consistent with Nutcracker Syndrome (NCS). Anatomically, renal veins drain into the inferior vena cava (IVC), being LRV three times longer than the right renal vein. LRV is usually placed behind the splenic vein and the pancreatic body, then in front of the aorta while being directly behind the descending superior mesenteric artery (SMA), in the aorto-mesenteric space, close to its termination in the IVC. LRV receives the testicular or ovarian vein and the left adrenal vein. NCS anatomy was described for the first time by Grant in 1937, but the term “nutcracker syndrome” is attributed to De Schepper, who defined as NCS the LRV compression between the aorta and SMA [1], which is currently labelled as “anterior NCS”. A less common variant is the “posterior NCS”, a condition occurring when a retro- or circum-aortic renal vein is crushed against the vertebral body [2]. An asymptomatic mesoaortic compression of LRV is deemed to be a quite common anatomical variant. NCS prevalence is unknown, likely because of under diagnosis due to the variable and a specific clinical presentation. However, it is estimated to be relatively more common in females, being usually diagnosed in the 3rd or 4th decade of life [2]. In small cohort studies, NCS has been observed in 70% of the cases of patients with severe orthostatic intolerance, in 18% of patients with idiopathic haematuria and 14% with orthostatic proteinuria [3]. The most common clinical NCS features include pelvic discomfort, left flank pain and gonadal varices. The main laboratoristic features, due to venous hypertension, are hematuria, anemia, proteinuria and chronic kidney disease (CKD) [4]. Several diseases, physiological states and anatomical variants can lead to “nutcracker-like” conditions as a result of LRV compression: before diagnosing NCS, the physician must exclude pancreatic or retroperitoneal cancers, abdominal vessels dilatations (such as abdominal aorta aneurysms) or malpositions (such as embracing testicular artery or high disposition of LRV), aortomesenteric lymphoadenomegalies, aortomesenteric space fibrosis, marked left renal ptosis and pregnancy [2]. Clinical signs and symptoms are paramount in NCS diagnosis because, even if this condition can be only confirmed by imaging, it is...