Laparoscopic nephrectomy in children for benign conditions: indications and outcome.

AIM: To analyze the indications and outcome of laparoscopic nephrectomy for benign non-functioning kidneys in children.
MATERIALS AND METHODS: The data of all patients operated over a 10 year period was retrospectively analyzed.
RESULTS: There were 56 children, aged 4 months to 12 years with a male: female ratio of 2.3:1. The most common presentation in boys and girls was urinary tract infection (UTI) (61.5% and 47.05% respectively). Incontinence due to ectopic ureter was a close second in girls (41.17%). The most common underlying conditions were vesico-ureteric reflux (42.85%) and multicystic dysplastic kidney (23.2%). There were 6 nephrectomies, 4 heminephroureterectomies and the remaining nephroureterectomies. All children tolerated the surgery well. One patient underwent a concomitant cholecystectomy. The post-operative problems encountered were UTI (1), urine retention (1), pyonephrosis in the opposite kidney and development of contra-lateral reflux (1). All others had resolution of pre-operative symptoms with good cosmesis.
CONCLUSIONS: As per available literature, this appears to be the largest Indian series of pediatric laparoscopic nephrectomies for benign non-functioning kidneys. Laparoscopic approach gives excellent results provided pre-operative investigations rule out other causes for the symptoms with which the patient presents. Often it is not the kidney but the dilated dysplastic ureter which is the seat of stasis and infection or pain and therefore should be completely removed.

INTRODUCTION

Nephrectomy is performed in children for benign poorly functioning nephroureteral units causing recurrent urinary tract infections (UTIs), abdominal pain, hypertension etc. The laparoscopic route has gained popularity for their removal since its introduction, irrespective of age and appears to generate less stress response.[12] The additional benefit of small scars is appreciated by parents during decision making. In this retrospective study, we analyzed the etiology of these poorly functioning or non functioning kidneys (NFK) and postoperative relief following laparoscopic nephrectomy (LN) over a 10 year period. As per available literature, this appears to be the largest Indian series of LN for benign NFK in children.

MATERIALS AND METHODS

Although retrospectively reviewed, data had been prospectively collected in all patients. Primary etiology, indications for surgery, previous or simultaneous intervention was noted along with measurement of blood pressure and renal function tests (RFT). Ultrasonography (USG) of the kidney, ureter and bladder (KUB) and dimercapto-succinic acid scan (DMSA) were performed in all patients. Micturating cysto-urethrogram (MCUG), diuretic renogram and intravenous urogram (IVU) were performed as indicated. Patients with suspected ectopic ureteric opening also underwent magnetic resonance urography (MRU). Contrast enhanced computed tomography (CECT) was performed in a few patients.

Written informed consent for the procedure including possible conversion to open was taken in all cases. An enema was administered the night prior to surgery. Prophylactic antibiotic (intravenous cefotaxime 50mg/kg) was given at induction. Patients were catheterized and a nasogastric tube placed for decompression of the stomach. All surgeries were performed under general endotracheal anesthesia and monitored by capnography during surgery.

Surgical technique

The child was placed in a semi-lateral position with the side to be operated raised at an angle of about 30-40° with a bolster underneath and the patient strapped to the operating table after padding pressure points. A 10 mm umbilical port was inserted through an infra-umbilical curvilinear incision by open technique. Pneumoperitoneum was created using carbon dioxide (CO-2) at a pressure of 8-10 mm Hg and flow rate of 0.8-1.5 lit/min. Two 5 mm working ports were then inserted under vision, in the epigastrium (midway between the xiphisternum and umbilicus) and in the mid-clavicular line just below the level of the umbilicus on the side to be operated. Occasionally an additional 5 mm port was placed. A finger of a sterile glove was wrapped snugly around all the ports 2.5-3.5 cm from the distal end prior to insertion. All ports were fixed to the skin with 2-0 Vicryl suture. These steps prevented displacement of the port and leakage of gas. The ipsilateral colon along the white line of Toldt as well as the hepatic/splenic flexure was completely mobilized. The Gerota's fascia was opened, the vascular pedicle isolated and artery and vein separately ligated. In some cases of multicystic dysplastic kidneys (MCDK) the vessels could be directly coagulated. The ureter was traced as close to the bladder as possible safeguarding the vas deferens/gonadal vessels. The patient was then placed back in supine position and the entire operated area irrigated with normal saline till clear. No drain was placed in any patient. The specimen was removed through the umbilical port site. The sheath was closed with interrupted 2-0 Vicryl and skin with Vicryl Rapide. All the wounds were infiltrated with 2% bupivacaine. Photographs of all specimens were taken with dimensions and stored.

Orals were resumed on the first postoperative day in the absence of ileus. Antibiotics were given for the first 48 hours after surgery in all patients and uroprophylaxis continued depending on the status of the opposite kidney. Intra-operative details, post-operative hospital course and follow up for resolution of pre-operative symptoms, port site healing and function of the remaining kidney were noted.

Statistical analysis: Quantitative data was analyzed and mean and standard deviation calculated. Conversion rates and operative times were compared between the first ten cases and the remaining cases using chi square test and unpaired t test respectively. P value less than 0.05 was considered significant.

RESULTS

Between May 2004 and August 2013, 6 laparoscopic nephrectomies (LN), 4 laparoscopic heminephroureterectomies (LHNU) and 46 laparoscopic nephroureterectomies (LNU) were performed in children, aged 4 months to 12 years (mean: 5.13 years), weighing 6.56-50 kg (mean: 17.05 kg) and height ranging between 70-143 cm (mean: 105.3 ± 19.2 cm). There were 39 boys and 17 girls (M: F ratio: 2.3:1).

Renal function on DMSA scan was nil in 39, <10% in 14 and 10-15% in 3. RFT's were deranged in 4 patients of whom 3 had posterior urethral valves (PUV) and one had bilateral pelviureteric junction obstruction (PUJO). An equal number of operations were performed on the left side (M-21, F-7) and on the right side (M-18, F-10). Four girls, the youngest aged 7 months, underwent upper pole LHNU.

The common presentations are shown in Table 1 with some patients having more than one feature. The underlying conditions are shown in Table 2.

Table 1

Presenting features of children who underwent laparoscopic nephrectomy

Table 2

Primary etiology of poorly functioning kidneys

Children with MCDK (n=13) presented with hypertension (7), flank pain (3) and UTI (2 - both with associated vesicoureteric reflux [VUR]). 2 children were asymptomatic. Ureters with variable degrees of atresia/dysplasia were seen except in 2 boys with associated VUR who had a fairly uniform ureteric diameter of 5-6 mm ending blindly at the level of PUJ. [Figures 1a and b]

Figure 1a

Laparoscopic nephroureterectomy specimen showing multicystic dysplastic kidney, atresia at the pelviureteric junction and distal prominent ureter in an 18-mo-old boy

Figure 1b

Micturating cystourethrogram in the same patient showing bilateral vesicoureteric reflux and blind ending proximal ureter

Overall, 15 boys aged 2.5 -11 years (mean 5.7 yrs) who had previously undergone PUV fulguration underwent LNU. Of these, 5 had dilated non refluxing systems and 10 associated VUR. The ureteric length and width ranged from 8-23 cm (mean 15.03 cm) and 0.8-5.5 cm (mean 1.45 cm) respectively while the renal length measured 2-8 cm (mean 4.65 cm). Bifid pelvis with their own atrophic renal moieties was seen in 2 patients. Among the 15, one 4 year old boy underwent a simultaneous lap cholecystectomy for gall stones along with right LNU with no additional port placement.

Six patients had undergone previous abdominal procedures: ipsilateral percutaneous nephrostomy insertion (2 for assessment of function and 2 for pyonephrosis), vesicostomy followed by closure after PUV fulguration (1), ventriculoperitoneal shunt for congenital hydrocephalus (1), and colostomy followed by its closure for anorectal malformation (1).

The other associated urological anomalies included anterior urethral diverticulum-previously excised and repaired (1); bifid glans with coronal hypospadias (1) and ectopically located small kidney in 2 girls with associated single system ectopic ureter presenting with incontinence. The contralateral unit had VUR (7), non VUR hydroureteronephrosis (3) and hydronephrosis (2).

The operative time ranged from 50-210 minutes (mean: 138.0 ± 48.9 min) with the least time being taken for removal of MCDK. In the first 10 cases, the operative time ranged from 90-210 min (mean: 171.0 ± 42.5). In the remaining, the operative time ranged from 50-210 min (mean: 128.8 + 45.1) (P value = 0.015).

Overall, 5 cases were converted to open (8.9 %), 2 having associated hypertension. In the first 10 cases of this series, 3 were converted to open (30%), one due to equipment failure and two due to bleeding. In the remaining 46, the first case of LHNU in a 3 yr old girl required conversion because of a bleed. Another patient who had previously undergone an ipsilateral percutaneous nephrostomy for pyonephrosis as well as a ventriculo-peritoneal shunt for hydrocephalus was converted due to dense perinephric adhesions leading on to a small colonic injury. The conversion rate was significantly lower after the first 10 cases (P < 0.05).

All specimens could be removed through the umbilical port although in 6 cases because of the size of the kidney, the incision had to be extended by 1-2 cm. In cases of MCDK, puncture of the cysts after presentation at the umbilical site just prior to removal was enough for easy removal through the port site.

Overall, the children tolerated the procedure well including a 4 month old baby. A 2.5 year old child (weight 9.8 kg) had fall in oxygen saturation at the start of the procedure which recovered after reducing gas pressure and flow rates. Another child had transient arrhythmia during dissection of right renal vessels. No patient required blood transfusion. There were no immediate postoperative problems. Children were allowed orally the day after surgery and went home on the 2nd-3rd postoperative day.

In the early follow up, a 1½- year-old boy with MCDK and bilateral VUR who had undergone LNU and simultaneous successful contralateral cystoscopic dextranomer hyaluronic acid injection had asymptomatic UTI (1), a 4-year-old girl with grade IV VUR developed urine retention (1), while another 3 year old child of PUV and ipsilateral grade V VUR developed pyonephrosis in the remaining kidney about 3 weeks after nephrectomy. A 7-year-old boy with neurogenic bladder and ipsilateral grade IV VUR developed poor stream and dribbling after surgery and was found to have contralateral VUR on MCUG. All others had resolution of preoperative symptoms. One child developed superficial umbilical port site infection.

Available histopathological examination reports of kidney specimens revealed MCDK (11), multicystic nephroma (1), dysplastic kidney (9), chronic pyelonephritis (7), end stage renal disease (5), reflux nephropathy (5), hypoplastic kidney (3), tubulointerstitial nephritis (2) and PUJO (4).

One patient was lost to follow up. The remaining patients were followed up from 1-93 months (mean: 19.2 ± 22.9). Cosmetic result was excellent in all except one patient with a skin burn at a port site in the lower abdomen. One patient developed contralateral VUR with UTI on long term follow up. All other patients had resolution of pre-operative symptoms. No patient developed an incisional hernia or symptoms due to post-operative adhesions.

DISCUSSION

Laparoscopic nephrectomy has become the standard of care for removal of benign NFKs.[3] Many studies have demonstrated its safety in children, even in those weighing less than 10 kg.[145] In our series, 6 children (age ≤ 1 year) weighed less than 10 kg and 24 (age 1-5 years) were between 10 -15 kg. Age and lesser weight per se do not cause intra-operative problems so long as the surgeon and anesthetist take due care particularly with regard to the carbon dioxide pressure and inflation rate. It is associated with less stress response, minimal morbidity, better cosmetic results, less post-operative pain and shorter hospital stay as compared to the open technique and has been considered superior to open surgery by some authors.[267] Blood loss and complication rates are comparable to open techniques. Studies have shown that mean operative times decrease significantly after about ten LNs.[89] Our operative time and conversion rates also fell significantly after the first ten cases. With experience, other procedures can be performed simultaneously without much increase in operative time. One 4 year old boy, who had undergone PUV fulguration elsewhere, underwent a simultaneous laparoscopic cholecystectomy for gall stones along with right LNU with no additional port placements. After ligating and cutting the cystic duct and vessels, the grasping forceps on the gall bladder was used to lift the liver up facilitating dissection of the renal hilum. The gall bladder was dissected off its bed after completion of LNU.

While taking consent, the most common apprehension of parents was whether the child will survive with one kidney and the majority took more than one counseling session to agree for surgery. It has been our experience that while parents usually accept nephrectomy in the presence of a malignant condition like Wilms’ tumor, it is more difficult to convince them for the same for benign indications even though these poorly functioning renal units may be the cause of recurrent urinary tract infections, abdominal pain, hypertension etc. The most common indication in our series was VUR (42.85%) and MCDK (23.2%). Among 24 patients who had ipsilateral VUR, 37.5% were primary and 41.6% secondary to PUV. This is similar to that noted in other series as well.[57] Kim et al., in 2009 in a review of the available data on LN in children added hydronephrosis in addition to MCDK and VUR as the most common diagnosis cited by authors.[10] There is no information in these studies as to whether the VUR was primary or secondary. In our series, 4 children had PUJO, one of whom had associated calculi.

Huang in 1987 first described 21 cases of unilateral congenital megaureter associated with giant focal segmental ureteral dilatation associated with ureteral stenosis or atresia or a ureter of almost normal calibre.[11] One boy fulgurated for PUV elsewhere, presented at the age of 8 years with abdominal distension, UTI and left side gross VUR in a non-functioning renal unit. An unusually dilated giant megaureter with negligible renal tissue and initial difficulty in deciphering from the sigmoid colon was excised [Figure 2]. We had 2 other such interesting cases. One 12-year-old boy was referred with right upper quadrant abdominal pain for the past 3 years and had been initially managed as gastroesophageal reflux disease. USG KUB suggested right sided PUJO. There was no function on renal scans and IVU. CECT showed 2 cystic lesions one below the other in the right paravertebral region with only enhancing walls. A clumped up cystic lesion which tapered into a thin ureter above and below was excised. A 5-year-old girl presented with UTI, dribbling of urine, right sided hydroureteronephrosis with <5% function and left sided VUR. A ureter with varying widths and a distal blind end ectopically entering the vagina was excised. The kidney in both these children was atrophic.

Figure 2

Laparoscopic nephroureterectomy specimen showing giant megaureter secondary to reflux

In our series, 14 children were preoperatively diagnosed to have MCDK. An important differential diagnosis of this condition is a benign multicystic nephroma which was seen in an eight-year-old girl referred with complaints of flank pain and USG diagnosis of MCDK. Another important association is VUR seen in 2 boys aged 18 months [bilateral VUR –Figure 1b] and 6 months (ipsilateral VUR). The latter also had associated hypertension. Both the boys presented with UTI and underwent complete excision of the ipsilateral ureter, which is otherwise not often performed in children with MCDK where the ureter is known to be atretic. Here, the ureter was atretic only in the region of the pelviureteric junction but dilated below that. This blind ending ureter is a potential seat of infection later.

Dissection of MCDK was found to be the easiest. There is no surrounding inflammation, the Gerota's fascia is thin and the vessels are atretic. The operative time was more in children with pyonephrosis as the kidney was often heavy and very adherent to surrounding tissue. One such case with previous PCN insertion and in situ ventriculoperitoneal shunt, required conversion because of difficult dissection and small rent in the adjacent colon.

Complications encountered during and after LN may be related to the anesthesia, surgical procedure or the primary disease. There were no injuries during port insertion as the initial port was inserted by open technique and the rest under vision. The intra-abdominal space in children is less and care must be taken during port insertion and during dissection especially while using cautery. One 4-year-old girl had cautery burn likely from coupling injury during dissection of left lower ureter. In our series, the initial 3 conversions were done in the first 10 cases of which one was because of equipment failure. Overall complication requiring conversion was 4/56 (7.14%), 3 due to bleed. One of them had associated hypertension. In all the 3, bleed occurred during dissection of right renal vessels. Intra-operative arrhythmia was also noted in another patient undergoing dissection of right renal vessels. Esposito et al., in a study of the complications after laparoscopic pediatric urological procedures found a complication rate of 2.7%. They found that surgical team experience was not related to the complications as the more experienced teams did not report a lower complication rate than the less experienced teams.[12] However, our experience has been different with conversion rate nearly zero in the last few years. None of our patients developed an incisional hernia or symptoms due to post-operative adhesions.[13] There have been no delayed re-explorations. Development of post-operative UTI suggests persistent problems in the bladder. No patient had symptoms due to residual stump except one who also had contra-lateral grade III VUR in a neurogenic bladder. The opposite side renal unit and bladder / urethra should be therefore thoroughly assessed before embarking on LNU.

As per the indexed medical literature, ours is the largest series of LN in children from India with follow up.[141516] It is important to remove the entire ureter in a majority of pediatric nephrectomies as seen in our series where it is often the redundant ureter rather than the kidney which is not only the seat of infection but occasionally the cause of pain.

In conclusion, we would like to highlight the feasibility and safety of LN in children with benign NFK. The procedure should be preferred over the open technique wherever basic expertise and technical facilities are available. The learning curve for the procedure is not as steep as it was previously thought to be and longer operative times and higher conversion rates in the initial period must not act as a deterrent.