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Clinical case: Horseshoe kidney transplantation: want to learn more about it?

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Clinical case: Horseshoe kidney transplantation

After reviewing this case you should be able to describe the following:

  • How and why a horseshoe kidney develops embryologically? Where is such a kidney typically located and why? What does the “watershed” area of a horseshoe kidney mean?
  • Why a transplanted kidney is typically placed in the iliac fossa rather than in the normal position for a kidney? How is it possible to do an end-to-end anastomosis of the renal arteries to the internal iliac artery and not cause ischemia in the pelvic and/or gluteal structures?
  • Why immunosuppression was instituted in the patient. And what are the risks of immunosuppressants? 
  • What is the meaning of serum creatinine levels relative to kidney function?
  • Why kidney transplant surgeons typically prefer to use a left donor kidney rather than a right one (although not in this case of a horseshoe kidney)?

This article is based on a case report published in the Journal "Case Reports in Surgery" in 2015, by Caroline C. Jadlowiec, Beata E. Lobel, Namita Akolkar, Michael D. Bourque, Thomas J. Devers, and David W. McFadden.

It has been modified and reviewed by Joel A. Vilensky PhD, Carlos A. Suárez-Quian PhD, Aykut Üren, MD.

Case description

History and investigations

A 30-year-old male had had his father’s right kidney implanted into his left iliac fossa when he was 19 years old (see Figure 1 for normal kidney anatomy).

Figure 1. Normal kidney anatomy. Typically transplant surgeons prefer to use the left kidney and the reason is obvious in this figure (see Objective 5 explanation). The main left renal artery is hidden by the vein. The right renal artery passes deep to the IVC (inferior vena cava) and is thus also hidden from view in this image.

After 10 years of adequate functionality the transplanted kidney was rejected by the son’s immune system and the patient had to resume hemodialysis. A new transplant was needed and the son’s mother was the only available donor. However a magnetic resonance angiogram (MRA) revealed that the transplant procedure would be more complicated than normal because the mother had an asymptomatic horseshoe kidney (Figures 2).

Figure 2. Photograph of horseshoe kidney in a cadaver. The minimized image is a magnetic resonance angiogram (MRA) showing horseshoe kidney in the patient in this case.

Intervention and management

The surgeons decided to approach the horseshoe kidney anteriorly from the left by entering the peritoneal cavity and mobilizing the descending colon. The horseshoe kidney was surgically transected through its watershed area (Figure 2). The left nephrectomy was accomplished with little hemorrhage (Figure 3A). The transected surface of the remaining right kidney was sutured close.

Figure 3. Intraoperative photographs. A: Exposure of the horseshoe kidney in the mother. B: Insertion of the left donor kidney retroperitoneally into the son’s right iliac fossa.

The removed left half of the mother’s horseshoe kidney was implanted into the son’s right iliac fossa with an end-to-side anastomosis of the renal vein to the external iliac vein. Mother’s left kidney had two renal arteries, which were too far apart to make a common connection to an iliac artery so the superior artery was anastomosed end-to-end to the right internal iliac artery and the inferior vessel end-to-side to the right external iliac artery, The ureter was implanted into the bladder (Figure 4).

Figure 4. Drawing of a donor kidney implanted into iliac fossa.

Evolution

Immunosuppression was implemented in the son using a standard regiment. The mother had an uneventful recovery and was discharged on the fifth postoperative day. The son developed a DGF (delayed graft response), which is very common in kidney transplant surgery. The patient began diuresis on the eighth postoperative day and renal function was progressively achieved. Three months postoperative, renal function stabilized. At the end of the first year, serum creatinine was found to be 128 μmol/L (1.45 mg/dL). At two months postoperative, mother and son were in good health. 

Surgical and anatomical considerations

Location and relations of the kidneys

Horseshoe kidneys occur in approximately 1 in 400-500 adults and are more frequently encountered in males (M:F; 2:1). When a potential kidney donor presents with vascular or urinary abnormalities such as a horseshoe kidney and there is no other suitable living donor, the only alternative may be to use a cadaver donation. But that process may entail long lists and waiting time, urgent surgery and poor compatibility. A continuing organ shortage in conjunction with large numbers of potential recipients sometimes requires using marginal donors or donors with vascular or urinary abnormalities. Use of kidneys from these donors compounds the difficulties of the surgical procedure.

Normally the human kidneys are situated in a retroperitoneal location, high in the abdominal cavity at a slightly oblique angle (Figure 1). Typically the right kidney is slightly lower than the left. The left is approximately at the T12-L3 level. Both kidneys are located directly inferior to the diaphragm with the right being posterior to the liver and the left being posterior to the spleen. The suprarenal (adrenal) gland is located on the superior pole of each kidney (Figure 1). However, when a kidney is not in its normal anatomical position as in a horseshoe kidney, the suprarenal glands are typically located in their normal anatomical position (Figure 5).

Figure 5. Axial CT scans of a patient with a horseshoe kidney showing the near normal location of the adrenal glands (highlighted with green). The superior pole of the left segment of the horseshoe kidney could be seen, which in this patient reaches a more superior level than the right.

The posterior abdominal wall forms the posterior relations of the kidneys. Specifically the muscles that form these relations include the:

The subcostal. iliohypogastric and ilioinguinal nerves also form posterior relationships of the kidney (Figure 6).

Renal vessels and their locations

Theoretically, each kidney receives a single artery directly from the aorta, but in many cases, the kidneys receive more than a single artery. Similarly, each kidney is typically drained by a single vein that drains into the inferior vena cava (Figure 1). The right renal artery passes posterior to the inferior vena cava and the left renal vein passes anterior to the aorta. This relationship is very useful for obtaining orientation in radiologic imaging, especially CT and ultrasound images.

Learn more about the kidney and related structures through these great resources!

Clinical case: Horseshoe kidney transplantation: want to learn more about it?

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