Rare combined variation of left suprarenal vessels associated with retroaortic left renal vein

Abstract

Suprarenal vascular variations should be known to surgeons performing laparoscopic adrenalectomy, partial nephrectomy, living donor nephrectomy and renal transplantation. A rare case of vascular variation of the left suprarenal gland was observed, in which the left suprarenal vein was draining into the inferior vena cava after crossing the abdominal aorta anteriorly, just below the origin of the superior mesenteric artery. The left inferior suprarenal artery was originating from the left gonadal artery, which originated from the abdominal aorta in front of the left renal artery. Besides this, the left renal vein passed obliquely downwards behind the abdominal aorta and drained into the inferior vena cava. The retroaortic left renal vein may lead to unilateral hematuria, left varicocele and could be a cause of infertility in men.

Introduction

The suprarenal gland is supplied by the superior, middle and inferior suprarenal arteries, which arise from the inferior phrenic artery, abdominal aorta and the renal artery, respectively. The left suprarenal vein is normally drained into the left renal vein and the right suprarenal vein is drained into the inferior vena cava. ¹ The gonadal artery arises from the front of the abdominal aorta at the level of the second lumbar vertebra. The gonadal vein on the right side drains directly into the inferior vena cava, whereas on the left side, into the left renal vein. The anatomical differences in the draining patterns of the suprarenal and gonadal veins of both sides are due to their embryological basis. The left renal vein receives the left testicular vein, the left inferior phrenic vein and the left suprarenal vein. It traverses to the right in front of the abdominal aorta and drains into the inferior vena cava.

Knowledge of suprarenal vasculature during laparoscopic adrenalectomy and adrenal vein sampling is necessary for surgeons and clinicians.^2,3 The retroaortic left renal vein can lead to left renal venous hypertension, varicocele and hematuria, making renal vascular variations clinically significant.^4,5 Further, combined vascular variations can be the cause of syndromes with different signs and symptoms in a particular patient.

Case report

During routine dissection classes for undergraduate medical students, we came across a unique vascular variation of the left suprarenal gland along with the retroaortic left renal vein in a male cadaver aged approximately 58 years. The inferior suprarenal artery originated from the left testicular artery. The left testicular artery originated from the abdominal aorta, just in front of the origin of the left renal artery. The left suprarenal vein, after emerging from the lower part of the left suprarenal gland, passed to the right side, in front of the abdominal aorta just below the origin of the superior mesenteric artery, through a very narrow gap between the aorta and the superior mesenteric artery. It then connected to the inferior vena cava instead of the left renal vein. The left renal vein, after emerging from the left kidney, was passing obliquely downwards and medially to the right, behind the abdominal aorta, just above the level of origin of the inferior mesenteric artery and then drained into the inferior vena cava. It received the left gonadal vein (Figure 1). However, the renal and suprarenal vasculature on the right side was found to be normal. The present combination of vascular variation is unique, rare and has not been previously reported to the best of our knowledge.

Figure 1.

Abdominal dissection revealed that the left suprarenal vein (LSRV) connected to the inferior vena cava (IVC). The inferior suprarenal artery (ISRA) originated from the left gonadal artery (LGA). The left gonadal vein drained into the left retroaortic renal vein (LRARV). The left retroaortic renal vein (LRARV) passed behind the abdominal aorta (AA) and connected to the IVC.

Discussion

Knowledge of different types of variations of renal and suprarenal veins is extremely important in laparoscopic adrenalectomy and in the treatment of renal trauma, renal transplantation, renovascular aneurysm and conservative or radical renal surgery. Very few studies and case reports of aberrant left suprarenal veins are available in literature. According to a study, variant venous anatomy of the suprarenal gland was encountered in 70 out of 546 adrenalectomies (13%), and variation in the adrenal venous connections occurred more often on the right side than on the left side. ⁶ Variant suprarenal vessels were found in 8 out of 83 cadavers (10%). ³ Another study reported the central vein of the left adrenal gland that joined the left inferior phrenic vein in 55 specimens to form an adrenophrenic trunk entering the left renal vein. ⁷ Rarely a case with the left suprarenal vein draining into the inferior vena cava is reported. A case similar to the present one has been reported in which the left suprarenal vein drained into the inferior vena cava along with the presence of the retroaortic left renal vein. ⁸ But, the present case, in addition to the abovementioned anomaly, has a variant origin of the inferior suprarenal artery from the left gonadal artery. Thus, variation on both the arterial supply as well as the venous connections of the suprarenal gland are unique in this case.

During laparoscopic adrenalectomy in patients with large tumors or pheochromocytoma, it is important to know about the variant drainage pattern of the suprarenal vein to avoid bleeding during surgical procedure. ⁶ Adrenal vein sampling in primary aldosteronism requires a good knowledge of the suprarenal vein and its possible variations. ² Surgeons performing laparoscopic adrenalectomy require a complete awareness of the venous communications of the suprarenal gland, as the vein needs to be ligated. ⁹ In the present case, as the left suprarenal vein is passing in between the aorta and the superior mesenteric artery, it can get compressed by these vessels and may hamper the venous drainage of the left suprarenal gland.

An anatomical study of the suprarenal arteries by Manso and DiDio mentioned that the suprarenal glands were supplied by the superior, middle and inferior groups of suprarenal arteries. In all cases, only the superior and the inferior groups were present, and the most variable was the middle arterial group. ¹⁰

Variant origins of the left inferior suprarenal artery from a testicular artery of high origin have been reported. ¹¹ This observation is similar to our case, in which the inferior suprarenal artery originated from the left testicular artery, which had an origin slightly above the normal level. However, in both the cases, there were no reports of a variant connection pattern of the left suprarenal vein or the retroaortic renal vein. This makes our case unique.

Kocabiyik et al. mentioned that the first nine lateral mesonephric arteries of an embryo disappear, excluding those supplying the metanephros, the gonads and the suprarenal glands. An anomalous origin of a left inferior suprarenal artery may be due to the persistence of one of the lateral mesonephric arteries that connects the gonadal and suprarenal artery. ¹²

Presence of a retroaortic renal vein is not uncommon. A computed tomography study reported the incidence of a retroaortic left renal vein and a circumaortic left renal vein as 1.8% and 4.4%, respectively. ¹³ A gender-based study on the prevalence of the retroaortic left renal vein reported its presence in men and women as 1.7% and 1.6%, respectively. ¹⁴ Hsieh et al. reported three cases of the presence of a retroaortic renal vein in which abdominal pain, flank pain, fever and hematuria were the major signs and symptoms. ⁴ A case of the retroaortic renal vein, which was associated with the left suprarenal vein, draining into the inferior vena cava has been previously reported. ⁸

During the vascular development of human embryos, almost all the major veins arise as capillary plexus, which later fuse to form fewer and larger veins. ¹⁵ During the process of vein formation, one of the venous channels connecting the suprarenal vein with the inferior vena cava may persist and thus, the suprarenal gland may directly drain into the inferior vena cava instead of the left renal vein.

Embryologically, a collar of veins encircling the aorta is formed from the anastomotic communications between the subcardinal and supracardinal veins. The dorsal portion of this anastomotic channel when persists, it forms the retroaortic renal vein. ¹⁶

A case study of a patient with a retroaortic left renal vein suffering from labile hypertension and left-sided varicocele was reported. ⁵ The retroaortic left renal vein may be compressed between the aorta and the lumbar vertebrae, leading to clinical conditions such as left renal venous hypertension or posterior Nutcracker Syndrome with or without hematuria, lower limb varices and varicocele, which may interfere with spermatogenesis and may lead to infertility. ⁸ However, in the present case, left varicocele was not observed. In patients presenting with hematuria, the possibility of them having a retroaortic left renal vein should be ruled out, as hematuria is reported to be associated with 22.22% of such cases in children. ⁸

Thus, it is advisable that the patient with left renal venous hypertension, varicocele and hematuria should be thoroughly examined for multiple renal and suprarenal vascular variations, which may be important to physicians, surgeons and radiologists. Knowledge of concurrent vascular variations reported here not only minimizes the diagnostic misinterpretation, but also prevents undue delay in the treatment of the affected individual.