A Detailed Study of Multiple Vascular Variations in the Upper Part of Abdomen.

INTRODUCTION: Knowledge of vascular variations near the kidney is of importance to many clinical disciplines such as nephrologists, radiologists, gastroenterologists, and general surgeons. Variant branches of the abdominal aorta and renal arteries are the victims of iatrogenic bleeding during surgery. We found multiple vascular variations in the upper part of the abdomen during our dissection classes.
METHODS: During the dissection classes of the abdomen for undergraduate medical students, we observed multiple vascular variations in the abdomen of an adult male cadaver. The vessels and surrounding viscera were cleaned using dissection instruments. Variations observed were photographed.
RESULTS: The right kidney had its hilum directed posteriorly. There were two right renal veins and a partially doubled left renal vein (LRV). The left suprarenal and gonadal veins drained into the upper LRV. There were two right renal arteries. Upper right renal artery gave origin to the right inferior phrenic and middle suprarenal arteries. There were two renal arteries on the left side also. The left upper renal artery gave a polar branch to the left kidney and divided into two branches before entering the kidney. The left inferior phrenic artery (IPA) gave two gastric branches to the fundus of the stomach.
CONCLUSIONS: The variations noted by us are of tremendous surgical application. The variant vessels might get damaged during surgical procedures if the surgeons are not aware of these variations. The most important among the variations reported here is the gastric branch of the IPA, which has not been reported yet.

Introduction

Vascular variations are commonly seen in the upper abdomen. The knowledge of variation of upper abdominal vessels is very useful for surgeons, nephrologists, endocrinologists, and radiologists. Renal vessels show several variations and most of them have been documented in the literature. The renal veins may be more than one in number may receive abnormal tributaries or may have variant relations.[1] The renal arteries also may vary in their number, point of entry into the kidney, source of origin, and distribution. The inferior phrenic arteries are also variable in position. They normally arise from abdominal aorta (AA); however, they may arise from the celiac trunk or renal arteries. However, their distribution to the stomach is very rare. We report here multiple variations associated with the upper abdominal vessels and discuss their radiological and surgical importance.

Methods

During the dissection classes of the abdomen for undergraduate medical students, we observed multiple vascular variations in the upper part of the abdomen of an adult male cadaver. These variations were found in the vicinity of kidneys and suprarenal glands. The stomach was reflected upward. Both the kidney's and suprarenal glands were dissected using dissection instruments. Further, the AA, inferior vena cava (IVC), and the major vessels in the vicinity of the kidney were dissected. IVC was cut and reflected downward along with the renal veins to display the variant renal arteries. Variations observed were photographed.

Results

The adult male body that we dissected had the following variations.

Duplication of the right renal vein: Both the right renal veins drained into the IVC [Figure 1]

Figure 1

Photograph of the dissection of right renal veins. The right kidney is facing backward. Duplication of the right renal vein with upper (1) and lower (2) right renal veins can be seen (AA = Abdominal aorta, IVC = Inferior vena cava, LRV = Left renal vein).

Partial duplication of the left renal vein (LRV): The LRV formed by the confluence of two renal veins emerging from the left kidney (LK). Upper renal vein received the left suprarenal and testicular veins [Figure 2]

Figure 2

Photograph of the dissection of the left renal vein. Upper division (1) of the left renal vein receiving the left testicular vein and left suprarenal vein can be seen (AA = Abdominal aorta, GB = Gastric branches of left inferior phrenic artery, IRA = Left inferior renal artery, IVC = Inferior vena cava, IPA = Left inferior phrenic artery, LK = Left kidney, LSG = Left suprarenal gland, LSV = Left suprarenal vein, PB = Phrenic branches of left inferior phrenic artery).

Duplication of the right renal artery: Upper right renal artery entered the kidney through the hilum. It gave origin to the right inferior phrenic artery (IPA) and right lower suprarenal artery at a distance of 3 mm from its origin. The lower right renal artery arose from the anterior surface of the aorta and entered the kidney through the hilum [Figure 3]

Figure 3

Photograph of the dissection of the right renal arteries. Upper (1) and lower (2) right renal arteries can be seen (AA = Abdominal aorta, IVC = Inferior vena cava (reflected down), RIPA = Right inferior phrenic artery, RISA = Right inferior suprarenal artery, RSG = Right suprarenal gland).

Duplication of the left renal artery: Upper left renal artery gave a polar branch to the LK which entered the kidney near the upper pole. After the onset of the polar artery, distally, the upper left renal artery divided again into two branches, which entered the kidney through the hilum. Lower left renal artery crossed between the two divisions of LRV and entered the kidney through the hilum [Figure 4]

Figure 4

Photograph of the dissection of the left renal arteries. Upper (1) and lower (2) left renal arteries can be seen (AA = Abdominal aorta, CT = Celiac trunk, IVC = Inferior vena cava (reflected down), IPA = Left inferior phrenic artery, LRV = Left renal vein, PA = Polar artery arising from left upper renal artery, RRA = Right renal arteries, SMA = Superior mesenteric artery).

The left IPA arose from the AA at the level of origin of superior mesenteric artery, apart from supplying diaphragm; it gave a reasonably large branch to the fundus of the stomach. The stomach had its usual blood supply in addition to this gastric branch [Figure 2]

The right kidney was over rotated so that its hilum was directed posteriorly [Figure 1].

Discussion

Renal vascular variations are often encountered. Many studies have reported the variations of renal vessels. Renal veins may vary in number, termination, and tributaries. Their relations with the aorta and the neighboring structures also may show variations. In a study by Zhu et al.,[1] variations of renal veins was found in 24.7% of cases. In this study, the variations of LRV were seen in 19.2%, and variations of right renal vein were seen in 1.7% of cases. Even in another study by Ballesteros et al.,[2] the LRV variations were more common (21.1%) than the right renal vein variations (0.64%). Nayak et al.[3] have reported the presence of retropelvic tributary for the LRV. In the current case, there was a complete duplication of the right renal vein. The LRV had a partial duplication.

Renal arteries show frequent variations. In a multidetector computed tomography (CT) angiography study, Çinar and Türkvatan[4] have found renal arterial variations in 31.3% cases. In this study, 22.2% patients had two, 7.5% had three, 1.4% had four, and 0.2% had five renal arteries. In a study by Saldarriaga et al.,[5] additional renal arteries were found in 22.3% of cases. Additional renal arteries were more common on the left side (32.0%) compared to the right (23.3%) in a study by Satyapal et al.[6] Gulas et al.,[7] have reported that the prevalence of accessory renal arteries is low in South East Asian countries than the Western countries. According to their study, it fluctuates from 4% in Malaysian to 61.5% in Brazilians. In a study on kidney donors by Munnusamy et al.,[8] 51% of donors had variations in the renal artery, and 13% each had accessory renal arteries on the right and left sides. In a CT scan study by Johnson et al., on Caribbean population,[9] accessory renal arteries were present in 36.1% of patients. About 23.5% patients had accessory arteries on the left, and 17.9% had them on the right side. Buisman et al.[10] have reported a common renal arterial trunk. Mao and Li[11] have reported the origin of the accessory renal artery from the testicular artery.

The IPA usually arises from the AA, just after the entry of the aorta into the abdomen. It supplies the undersurface of the diaphragm, the peritoneum covering it and also the suprarenal gland. It rarely arises in common with the celiac trunk. In the current case, it gave a large branch that supplied the fundus of the stomach. To the best of our knowledge, this type of variations has not been reported earlier.

During early development, the hilum of kidney faces anteriorly. As the development proceeds, the kidney rotates along its vertical axis in medial direction so that the hilum faces medially. If the rotation is less, the hilum faces anteriorly and if it is more, the hilum faces posteriorly. In the current case, the hilum of the right kidney was directed posteriorly. Posterior variant of the hilum is less common than the anterior variant.[1213]

Main clinical message of the current case

Thorough knowledge of renal vascular variations is required during renal transplant surgeries to avoid iatrogenic bleeding. The knowledge is also useful to radiologists in the interpretation of the CT scan and images of magnetic resonance imaging. Additional renal vessels and posteriorly placed hilum of the right kidney in the current case makes the case more interesting and important because this can lead to the compression of the renal vessels at the hilum. The gastric branch of IPA might bleed during gastrectomy due to its rarity. It might also adversely affect the therapeutic embolization of gastric vessels.

Conclusions

Knowledge of concurrent variations of renal vessels, IPA, and the position of hilum of kidney makes this case unique. The case may be of special interest to surgeons, radiologists, nephrologists, and endocrinologists.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.