Laparoscopic heminephrectomy of a horseshoe kidney.

Minimally invasive surgery has revolutionized surgery for urologic disorders, and laparoscopic procedures have become widely available for several different ablative and reconstructive operations. Laparoscopic heminephrectomy in patients with horseshoe kidney can be a technically challenging procedure due to aberrant vessels, functional parenchyma in the isthmus, and abnormal location. We report the management of a case of symptomatic nonfunctioning left moiety of a horseshoe kidney with emphasis on its surgical technique combined with a review of the literature. Laparoscopic heminephrectomy is a feasible option in the surgical management of benign and malignant conditions of the horseshoe kidney and can be performed safely using a transperitoneal or a retroperitoneal approach.

INTRODUCTION

It has been nearly 2 decades since the first description of a laparoscopic nephrectomy by Clayman et al.[1] Since then, laparoscopy has revolutionized the minimally invasive management of benign and malignant renal disease. Congenital renal anomaly may pose a technical challenge during laparoscopic nephrectomy due to complex vascular anatomy.

Horseshoe kidney, the most common fusion anomaly, occurs in up to 0.25% of the general population. Although most horseshoe kidneys are asymptomatic, calculi, pelvic ureteric junction obstruction and renal masses are most frequent findings that require surgery.[2] Since the initial report of a laparoscopic nephrectomy, few authors have advocated the laparoscopic approach for benign and malignant conditions associated with a horseshoe kidney.[3-25] We searched previous reports using the PUBMED database and the specific key words “horseshoe kidney,” “laparoscopy,” “nephrectomy,” “heminephrectomy,” and “congenital kidney anomaly.” All articles identified in the English language were reviewed, and 2 non-English reports were excluded.[24-25] We describe our experience and a detailed review of the literature.

CASE REPORT

A 32-year-old male presented initially with a history of intermittent left loin pain. He was obese with a BMI of 39. He was advised to lose weight before surgery, but because pain was affecting his work and mobility, he opted to have surgery without any delay. He smoked 10 cigarettes a day and drank 15 units of alcohol per week. His blood biochemistry including urea and electrolytes was satisfactory. An abdominal examination showed mild tenderness over the left renal angle. An intravenous urogram (IVU) demonstrated a horseshoe kidney with poor excretion on the left side. He underwent a retrograde ureterogram, and ureteroscopy was attempted. It was felt he had a possible stricture at the ureteropelvic junction. A double-J stent was placed; however, it was removed 48 hours later due to stent symptoms. A CT scan showed a horseshoe kidney with a normal-functioning right moiety and hydronephrotic left moiety with a very thin cortex and no evidence of any renal tract calculus (.

Computed tomography demonstrates the large hydronephrotic left moiety (arrow) of the horseshoe kidney.

Subsequently, the patient underwent a MAG3 scan, which showed a nonfunctioning left moiety. The options of an open or laparoscopic nephrectomy were discussed, and the patient was scheduled for a transperitoneal, laparoscopic nephrectomy.

During pre-assessment, it was noted that he had symptoms suspicious of sleep apnea syndrome. His Epworth sleepiness score[26] was 16 (>10 is abnormal). He underwent a formal sleep study and was diagnosed with sleep apnea syndrome. He was commenced on continuous positive airway pressure (CPAP) ventilation at night.

At surgery, the patient was placed in a right lateral position, and 5 ports were placed. The camera port was placed lateral to the umbilicus followed by two 5-mm ports above and below the camera port (∼5cm) along the lateral border of the rectus muscle. Two 12-mm ports were in the anterior axillary line. A 10-mm (ENDO RETRACT™II, Auto Suture, Norwalk, CT).

A 5-prong fan retractor was used to facilitate blunt dissection. The colon was mobilized, and the upper pole of the kidney was dissected. Multiple vessels were clipped with a Hem-o-lock and divided. The upper pole was freed laterally and posteriorly. Gonadal vessels were identified and traced upwards. The kidney was mobilized at the lower pole. The kidney was dissected medially, and the upper part of the isthmus was identified. The ureter was identified and divided after clipping. Gonadals were identified and divided after clipping. The upper and lower poles of the kidney were lifted to visualize the isthmus. The isthmus was isolated and clipped with a 15-mm Hem-o-lok (and was divided with a Harmonic scalpel (. A PDS Endoloop was also tied around the isthmus. The kidney was freed, bagged, and removed through the extended lower port site. A drain was placed and was removed after 24 hours. The total operating time was 180 minutes, and estimated blood loss was 200mL. The patient spent 1 night in the intensive care unit due to his sleep apnea. He subsequently recovered well and was discharged home on postoperative day 4.

The isthmus (arrow) of the horseshoe kidney is clipped with a 15-mmHem-o-lok and transacted with a Harmonic scalpel.

The histopathology revealed chronic pyelonephritis most likely attributable to pelviureteric junction obstruction. He was symptom free at discharge from the clinic 9 months after surgery with no evidence of port-site hernia.

DISCUSSION

The horseshoe kidney is probably the most common of all renal fusion anomalies. In this anomaly, 2 distinct renal units lie vertically on either side of the midline and are connected at their respective lower poles by a bulky parenchymatous or fibrous isthmus that crosses the midplane of the body. Generally, the isthmus is bulky and consists of parenchymatous tissue with its own blood supply.[27] The isthmus is located adjacent to the L3 or L4 vertebra just below the origin of the inferior mesenteric artery from the aorta. As a result, the horseshoe kidneys tend to be somewhat lower than normal in the retroperitoneum. The isthmus most often lies anterior to the aorta and vena cava but very rarely may pass between the inferior vena cava and the aorta or even behind both great vessels.[28,29]

Often, one-third of all patients with a horseshoe kidney are asymptomatic, and the anomaly gets noticed incidentally on radiologic examination. The most common associated finding in horseshoe kidney is ureteropelvic junction obstruction, which occurs in up to 35% of cases and is often the cause of problems. Kidney stones develop in 20% to 60% of patients and may be associated with obstruction and recurrent infections. Urinary stasis and urolithiasis also predispose the horseshoe kidney to infection, which occurs in 27% to 41% of patients. The frequency of certain neoplasms is higher. Renal cell cancer, the most common, accounts for 45% of all tumors. The risk of Wilms’ tumor is 2-fold in a horseshoe kidney and accounts for 28% of malignant lesions. Transitional cell cancer and sarcoma account for 20% and 7% of tumors, respectively.[30]

Various authors have demonstrated that a laparoscopic approach to urologic disease of the horseshoe kidney is an effective and equivalent minimally invasive alternative to traditional open surgery. Depending on the surgeon's expertise, different approaches have been used.[2-25] These include transperitoneal, retroperitoneal, and hand-assisted. Anatomic variations like lower renal location, aberrant vessels, and the isthmus necessitate special consideration during laparoscopic surgery.

There is a wide variation in horseshoe kidney vascular supply.[2] In 30% of the cases, it consists of one renal artery for each kidney,[31] but the blood supply may be atypical, with 1 to 8 renal arteries supplying one or both kidneys.[32] The isthmus and adjacent parenchymal masses may receive a branch from each main renal artery, or they may have their own arterial supply originating from the aorta (65%) either above or below the level of the isthmus.[2] Not infrequently, this area is supplied by branches from the inferior mesenteric artery, the common or external iliac arteries, or the sacral arteries.[33]

Appropriate imaging is crucial in presurgical planning to identify the renal vasculature and orientation of the collecting system. An aberrant vascular supply is one of the major anatomic features in horseshoe kidneys; thus, the vascular supply cannot be easily predicted during intervention. Therefore, angiography is indispensable in the preoperative planning, especially in patients with renal cancer.

A MEDLINE search revealed 23 (27 patients) case reports of nephrectomy for horseshoe kidney with laparoscopy, published between 1995 and 2010. Two of these reports published in French and Japanese were excluded. Patient data are summarized in . Flank pain was the most common presentation, and 4 patients had renal mass. Most authors used computerized tomography to assess vascular anatomy.

A transperitoneal approach was used in the majority (15) of cases, while a retroperitoneal route was used in 5 cases, and 6 patients were treated with a hand-assisted approach. This procedure can be technically demanding due to variable vasculature and abnormal anatomy; therefore, a few simple steps may facilitate a good outcome. First, identification of the ureter is important as is insertion of a double J stent or ureteric catheter. Second, to start dissection of the upper pole, it is helpful to first identify the vasculature. In a horseshoe kidney, most of the vessels are above the isthmus. Next, we recommend releasing the lower pole; this maneuver will allow lifting the kidney thereby isolating the isthmus very clearly. At this stage, it is critical to look for a direct blood supply to the isthmus. The isthmus can be divided in a variety of ways (, but in our case a 15-mm Hem-o-lok clip was used followed by a PDS Endoloop. In our case, no major problems were encountered during dissection.

Laparoscopic nephrectomy seems technically feasible, safe, and reliable for benign and malignant diseases in a horseshoe kidney. Anatomic variations necessitate proper imaging and special consideration for a successful outcome.

Table 1.

Summary of Patients Demographics and Treatment Data

Ref.	Age/Sex/Side	Presentation	Imaginga	Pre-auxiliary	Approach	Ports	Division of Isthmus	Duration	Hospital Stay (Days)	Complications	Blood Loss
3	28 M Left	Hydronephrosis	CT	Nephrostomy Ureteric catheter	Trans-peritoneal	5	Endo-GIA	8 hr	3 days	Nil
4	61 F Right	Hydro	CT	Nephrostomy	Trans- peritoneal	4	Under direct vision (extra corporeal) electrocautery	270 min	9 days	Nil	270mL
5	28 F Left	Hydronephrosis	CT arteriogram	J stent Ureteric catheter	Trans-peritoneal	4	Endo-GIA	5.1 hr	4		50
6	17 M Right	Flank pain	USS, CT	Nephrostomy	Trans- peritoneal	4	Microwave coagulator	8 hr	12days	Paralytic Ileus	560mL
7	Left	Flank pain	USS, IVU, MAG 3, DMSA	Nil	Retro-peritoneal	3	Harmonic scalpel	3.5 hr	1 day	Nil	10mL
8	56 M Left	Flank pain Urinary tract infection	USS, CT, DMSA		Trans- peritoneal	?	Endostapler	3 hr	3 days	Nil	150mL
	48 M Left	Urinary tract infection	CT	J stent	Trans- peritoneal	?	Endostapler	3 hr	3 days	Nil	150mL
9	15 month M, Left	Hypertension	Not reported	Nil	Retro-peritoneal	3	Ultrasonic scalpel	115 min	4 days	Nil	-
10	55 M Right	Flank pain	CT		Retro-peritoneal	3	Harmonic scalpel @ level 5 Argon-beam laser coagulation	300 min	7 days		60mL
11	35 F Right	Urinary tract infection, Recurrent stones	IVU, CT		Hand-assisted transperitoneal	Hand port, 12mm x2	Endo-GIA	165 min	4 days		200mL
12	37 M Left	Flank pain, Stag horn stone	USS, DTPA		Retro peritoneal	4	Ultrasonic scalpel	80 min	2 days		50mL
13	52 M Left	Incidental renal mass	CT, Angio graphy		Trans peritoneal	3	Parenchymal suture + argon beam	195 min	2 dyas		400mL
14	20 F Left	Flak pain, Urinary tract infection	CT, Angio graphy	J stent	Hand-assisted trans peritoneal	Hand port, 12mm x2	Endo-GIA	165 min	4 days		150mL
15	65 M Bilateral	Renal failure		Dialysis	Hand-assisted trans peritoneal	Hand port, 12mm x3	Electrocautery	280 min	12 days	Sick sinus syndrome, cardiac complications	350mL
16	64 F Left	Haematuria, Renal mass	CT		Trans peritoneal	3	Electrocautery, Digital compression	360 min	4 days		?
17	52 M Right	Flank pain	USS, IVU, DTPA		Trans peritoneal	3	Bipolar energy (Gyrus) 60W coagulation	140 min	2 days		160mL
18	24 M Right	Flank pain	USS, CT, isotope scan	Nephr ostomy	Retro peritoneal	3	Endostapler	140 min	1 day		75mL
19	8 F Right	Abdominal pain	USS, CT, MAG3	Ureteric catheter pre operatively	Trans peritoneal	4	Electrocautery	302 min	10 days	Nil	50mL
20	63 F Left	Incidental mass	CT angio graphy		Hand-assisted transperitoneal	Hand port, 12mm x2	Endo-GIA	273 min	2 days	Nil	250mL
21	18 M Left	Hematuria following blunt trauma	CT		Trans- peritoneal	3	Bipolar coagulation	240	3	Nil	200
	19 M Left	Flank pain	USS, CT, DTPA		Trans- peritoneal	3	Bipolar coagulation	180	3	Nil	200
	57 M Right	LUTS, microscopic hematuria	IVU, CT, DMSA		Trans- peritoneal	4	Bipolar coagulation	160	3	Nil	200
22	48 F Left	Urinary tract infection	CT angio graphy		Trans- peritoneal	4	Endo-GIA	307	1	Colonic serosal tear	100
23	29 N/A	Kidney stones	?	Bilateral ureteric stents	Hand-assisted trans peritoneal	3	?	267	?	Skin separation	?
	27 N/A	Pelvis rupture due to trauma			Hand-assisted trans peritoneal	3	?	319	?	Urinoma. Anejaculation, neuralgia	?

NR=not reported, USS=ultrasound, CT=computed tomography, IVU=intravenous urography.

Table 2.

Summary of Treatment Data.

Reference	Pre-auxiliary	Approach	Ports	Division of Isthmus	Duration	Hospital Stay (Days)	Histology	Complications	Blood Loss (mL)
3	Nephrostomy Ureteric catheter	Transperitoneal	5	Endo-GIA	8 hrs	3	NR	0
4	Nephrostomy	Transperitoneal	4	Under direct vision (extra corporeal) electrocautery	270 min	9		0	270
5	J stent Ureteric catheter	Transperitoneal	4	Endo-GIA	5.1 hrs	4			50
6	Nephrostomy	Transperitoneal	4	Microwave coagulator	8 hrs	12		Paralytic Ileus	560
7	0	Retroperitoneal	3	Harmonic scalpel	3.5 hrs	1		0	10
8		Transperitoneal	?	Endostapler	3 hrs	3		0	150
	J stent	Transperitoneal	?	Endostapler	3 hrs	3		0	150
9	0	Retroperitoneal	3	Ultrasonic scalpel	115 min	4	NR	0
10		Retroperitoneal	3	Harmonic Scalpel at level 5; Argon-beam laser coagulation	300 min	7	pT1 garde 1 clear-cell carcinoma		60 .
11		Hand-assisted transperitoneal	Hand port, 12mm x2	Endo-GIA	165 min	4	Chronic pyelonephritis		200 .
12		Retroperitoneal	4	Ultrasonic scalpel	80 min	2			50
13		Transperitoneal	3	Parenchymal suture + argon beam	195 min	2	pT2 clear cell carcinoma		400 .
14	J stent	Hand-assisted transperitoneal	Hand port, 12mm x2	Endo-GIA	165 min	4	Chronic inflammation		150
15	Dialysis	Hand-assisted transperitoneal	Hand port, 12mm x3	Electrocautery	280 min	12		Sick sinus syndrome, cardiac complications	350
16		Transperitoneal	3	Electrocautery, Digital compression	360 min	4	pT2N0M0 clear cell car		NR
17		Transperitoneal	3	Bipolar energy (Gyrus) 60W coagulation	140 min	2			160
18	Nephrostomy	Retroperitoneal	3	Endostapler	140 min	1			75
19	Ureteric catheter preoperatively	Transperitoneal	4	Electrocautery	302 min	10		0	50
20		Hand-assisted transperitoneal	Hand port, 12mm x2	Endo-GIA	273 min	2	pT2 clear cell carcinoma	0	250
21		Transperitoneal	3	Bipolar coagulation	240 min	3		0	200
21		Transperitoneal	3	Bipolar coagulation	180 min	3		0	200
21		Transperitoneal	4	Bipolar coagulation	160 min	3		0	200
22		Transperitoneal	4	Endo-GIA	307 min	1	XPN	Colonic serosal tear	100
23	Bilateral ureteric stents	Hand-assisted transperitoneal	3	NR	267 min	NR		Skin separation	NR
		Hand-assisted transperitoneal	3	NR	319 min	NR		Urinoma. Anejaculation, neuralgia	NR

aNR=not reported.