Nutcracker syndrome (NCS), which is commonly known as left renal vein entrapment syndrome, is due to hematuria with no glomerular causes and has difficulties in diagnosis. ¹ NCS is a sporadic vascular compression disease in the left renal vein (LRV) gets compressed, amidst superior mesenteric artery (SMA) and the abdominal aorta. Proteinuria, left lower quadrant of the abdomen pain and presence of blood in the urine are some of the symptoms which might be a presentation in this condition. ² In the year 1937, Grant who was an anatomist detailed the position of the LRV between the SMA and the abdominal aorta and that it shows itself like a nut held between the fangs of a nutcracker. ³ de Schepper, in the year 1972, first used the term NCS. ⁴ This sporadic condition may be seen in pediatric or adult patients, with the cause being unknown. It is characterised by the compression of the LRV, which might result in reduced venous drainage thus subsequently dilatating the LRV. ⁵ Inspite of many diagnostic parameters, NCS prevalence is not known, the reason here could be due to the plethora of symptoms, which includes left lower abdomen pain, proteinuria, hematuria, and compression of the pelvis in females (dysmenorrhea, dyspareunia, pelvic pain for a long time), and varicocele might be presented in men. ⁶ Although there’s a study conducted for a 1000 CT abdomen, where anterior NCS was found to be around 4.1% of cases. ⁷

In this report, we have described a rare presentation of a female patient in her mid 20’s, complaining of pain on left abdominal side for ten days, along with hematuria in the emergency department of Shalinitai Meghe Superspeciality Centre. The patient was undiagnosed until she was of this age before she visited the emergency department of the Shalinitai Meghe Superspeciality Centre, Wardha, India. This is a rare presentation involving several clinical conditions and also involving diagnostic challenges.

A female aged 25 years, college student by profession, resident of a small village in Central India, came with complaints of pain in abdomen for 10 years, painful menstruation (dysmenorrhea), easy fatigability for 5 years and blood in urine for 1 week. The clinician referred the patient for CECT (Contrast enhanced computed tomography) abdomen evaluation. History of vomiting, loose stools, fever, cough or cold is absent.

General examination revealed the patient was conscious and well oriented. Vitals measure were a follows- Fever:absent, pulse rate: 89/min, respiratory rate: 24/minute, blood pressure (BP) was found to be slightly high: 140/96 mm of Hg. 98% (SpO ₂) was the oxygen saturation. Any other remarkable findings were not seen in the general examination.

On clinically examining the patient, it was found that the Glasgow Coma Scale score and all the reflexes were normal in the CNS (central nervous system) examination. She was conscious and well oriented to the persons around her. Along with that, the respiratory system (air entry equal bilaterally), cardiovascular system (no abnormal pulsations), and renal system were normal. However, the gastrointestinal system revealed a few abnormalities.

Mild tenderness over the lower left quadrant of the- abdomen was present. Any kind of abdominal distension was not seen.

Lab findings are shown in Table 1 below.

Lab values significantly show low hemoglobin levels, high Erythrocyte sedimentation rate (ESR), presence of albumin in urine and 10-12/hpf (High power field).

Upon Grayscale ultrasound, the proximal left renal vein was grossly distended, as shown in Figure 1. On USG, all the gastrointestinal structures appeared normal in texture, shape and size. Even the findings of the kidney, urinary bladder and the ureters, did not reveal any kind of focal lesions or calculus and were seen normal.

Sagittal CECT of abdomen revealed, compression of left renal vein by superior mesenteric artery (SMA), aortomesenteric angle of 21 degrees and a compression ratio of more than 3. As shown in Figure 2.

An Axial CECT abdomen showed narrowing of Left Renal Vein (LRV) in between the Superior Mesenteric Artery and Aorta with minimal breaking of LRV. There is evidence of pelvic congestion in the form of dilated pelvic veins in the adnexa. As shown in Figure 3.

The patient had also undergone Coronal CECT abdomen, which showed evidence of dilated left gonadal vein Figure 4. On CT Angiography, SMA-AORTA angle was reduced measuring 21 degrees. SMA-AORTA distance was 4 mm (reduced) Figure 5.

After giving a medical therapy consisting of ACE inhibitors, we placed an endovascular stent which is an alternate modality of intervention because there were observable symptoms like hematuria, pain and, dysmenorrhea in the patient. Open surgery is generally not preferred to a stent in these cases as there is increased duration of renal congestion, with higher chances of manifestations. Extensive dissection is usually done in this operation. Other treatments options have been described in the discussion section.

The main motive of this case is to exhibit the significance of regular analysis of urine and imaging for the detection of symptomatic and asymptomatic patients suffering from NCS, which is a sporadic reason for hematuria. It is a diagnosis of exclusion. Henceforth, at first, ruling out other possible causes of hematuria is necessary. Patients who are asymptomatic should be assessed through urine analysis for hematuria as a differential fir NCS. This could be established with imaging methods like USG, CT or MRI. NCS, though sporadic can be seen in practice, so it is important to know about it so that diagnosis and management of patients can be done correctly. A broad array of surgical options is available, and the appropriate choice for patients suffering from the syndrome can only be made by possessing a thorough understanding of theory and practicalities of these interventions. Thus, it is important that it is required to upgrade elementary knowledge of the NCS, which is the motive of this report and discussion.

The nutcracker syndrome introduces us to the compression of the LRV within the SMA and abdominal aorta. The pattern in which these three structures are anatomically placed was thought to look like a nut in a nutcracker and thus the name. This phenomenon is defined by extrinsic compression, which obstructs the flow into the inferior vena cava (IVC) from LRV. The titles, NCS and nutcracker phenomenon, are occasionally used as similar words in the writing. The Nutcracker phenomenon states the anatomical findings suggesting the nutcracker when clinical symptoms are absent. The title NCS is applied for those showing manifestations clinically related to nutcracker anatomy. ⁸

This condition is linked to the development of the LRV within the 6-8th gestational week from the collar of aorta and an improper angle formation of the SMA with the aorta. ² The severity and symptoms of this condition differ, indicating various degrees of compression of the LRV, hypertension, and the compensatory stage, which is associated with the emergence of collateral blood flow. The symptoms include flank and abdominal pain, autonomic dysfunction, dysmenorrhoea, dyspareunia, and fatigue. The pain felt is due to the inflammation pathway activated by venous hypertension. The diagnosis of NCS is possible only when left renal vein compression leads to specific symptoms, like left flank pain, proteinuria, anaemia and varicocele. ⁹ Studies have reported that NCS is more prevalent in females, particularly during their 3rd to 4th decades of life; the same in our case. ^{10 , 11} People affected by this condition are typically considered slim and tall, having low retroperitoneal and intra-abdominal mesenteric adipose tissue. This results in narrowing the angle between the SMA and the abdominal aorta. ¹¹

Ultrasonography (USG) can be used as the initial test for diagnosis of patients thought of NCS. In normal cases, the length of the LRV ranges from 6-10 cm, and the average diameter is approximately 4-5 mm. The normal gradient of pressure between the LRV and the IVC is 1 mmHg or lower. However, an elevated gradient exceeding 3 mmHg between the LRV and the IVC can be considered a diagnostic criterion for NCS. ¹² Imaging plays a crucial role in diagnosing NCS. In CT and magnetic resonance imaging (MRI), the taken average angle between the superior mesenteric artery and the aorta for normal patients is mostly within the range of 38 to 60 degrees, with a mean of approximately 45 degrees. ¹⁰ There are other studies which also show the same numbers for the aortomesenteric angle (AMA) in CT, which is used for diagnosis of NCS. ^{6 , 11}

Although venography, which measures the renal vein pressure gradient, is considered the gold standard for diagnosing NCS, it is an invasive technique that is often not required. ⁵ Thus, CT, USG or MRI are preferred as better non-invasive diagnostic modalities. In our case, we did not use venography because of its invasiveness, although Doppler USG was used. This has the ability to confirm the rise in the pressure gradient of the renal vein. Although, there are studies which suggest using CT as the primary diagnostic tool because of its greater efficiency. CT has the advantage of having a stretched assessment of abdominal structures. ¹³ In our patient, a CT scan was done, revealing a slightly decreased AMA linking the aorta and SMA, measuring 21 degrees, which is suggestive of NCS. Additionally, another significant finding on the CT for diagnosing NCS is the ratio of renal hilar to aortomesenteric left renal vein, ¹⁴ and in our case, this ratio was 5.12, which further supports the diagnosis of NCS.

There is a controversy regarding choice for treatment in NCS. This is mostly decided on the condition of the presenting patient. Conservative management is mostly opted for those patients who present with no severe complaints or mild or nil hematuria. ¹⁵ Surgical modality is mostly opted for cases presenting with severe hematuria due to which patients have severe anemia along with intense pain even after using analgesics or decreased function of kidney. ¹⁶ In medical therapy, angiotensin-converting enzyme (ACE) inhibitors can be utilized to treat protein in urine. Additionally, the use of acetylsalicylic acid is sometimes thought of, although it remains a subject of controversy, because it is observed to increase kidney perfusion in cases of NCS. ¹⁵ Placement of endovascular stent is an alternate modality of intervention. In our patient, we used this method of intervention as a treatment modality. Open surgery is generally not preferred to stent in these cases as there is increased duration of renal congestion, with higher chances of manifestations. In this type of operation, there is a necessity for extensive dissection. ⁸ The perfect stent should possess sufficient radial strength so that there is no stenosis, excellent conformability so that it fits to the epithelium of the vessel. It should be also taken care that there should be minimum shrinkage of its length so that proper positioning is established. ^{17 , 18}

The patient provided written informed consent for the study. The patient consented to the publication of her clinical details and images.