Retroperitoneal Laparoscopic Kidney Biopsy: Technical Tips for a Minimally Invasive Approach

Introduction

R enal biopsy is an essential diagnostic tool in the assessment of hematuria and proteinuria of glomerular origin, and in the evaluation of unexplained renal diseases. Currently, ultrasound-guided percutaneous kidney biopsy (PKB) is the standard procedure, ¹ considered mini-invasive and safe when performed by an expert renal physician in selected patients. Nevertheless, some conditions still represent a contraindication for PKB, such as bleeding diatheses, severe obesity, solitary kidney, polycystic kidney, multiple renal cysts, uncontrolled hypertension, and previous failed attempts at PKB. ^{2 –4} In these cases, one option is to resort to open renal biopsy (ORB). ⁵ Nowadays, however, laparoscopic kidney biopsy (LKB) provides a minimally invasive alternative to open biopsy, warranting direct vision of the kidney and, at the same time, lowering risk of postoperative morbidity. ^{2 –4} In the current study, we describe the technique and report our experience of laparoscopic biopsies in a contemporary series of 40 consecutive patients. In selected cases, we used a particular “ready-to-laparo” technique that allowed reaching the kidney through the 10-mm incision made for the Hasson trocar. Therefore, no gas was inflated, and Trucut biopsies were performed under direct vision. Both the classic laparoscopic and the “ready-to-laparo” technique demonstrated to be safe and effective bioptic methods.

Materials and Methods

Results

In all, 40 patients underwent LKB between 2001 and 2010. The mean patient age was 58.85 years (SD 10.87). Their mean serum creatinine at surgery was 3.02 mg/dL (SD 2.69). The indications for performing LKB instead of routine PKB are listed in Table 1. Biopsy results are summarized in Table 2. The classical laparoscopic approach was performed in 37 cases (92.5%). In three selected cases, the easy identification of the lower pole of the kidney through the 10-mm incision made for the Hasson trocar allowed execution of the “ready-to-laparo” bioptic technique. All biopsies were performed in less than 1 hour. All the biopsies were performed with an 18-gauge Trucut needle. Adequate renal tissue for a pathological diagnosis was obtained in all 40 patients, thus enabling a 100% procedural success rate. The most common pathological findings were glomerulonephritis (47.5%) and glomerulosclerosis (27.5%). Complications were reported only in three patients (7.5%): two cases of minor bleeding from the port site (grade 1 according to Clavien classification of surgical complications ⁶ ) and one case of persistent blood loss into the urinary tract that required interventional radiology (grade 3a).

Discussion

Nowadays, histopathological evaluation has become essential in the diagnosis of unexplained cases of renal failure, hematuria, and proteinuria of glomerular origin. The optimal bioptic procedure should always provide adequate tissue for a histopathological diagnosis with the least patient discomfort, minimal complications, and as little use of resources as possible, with regard to time required for the procedure, equipment, and other resources. ⁷ Up to date, the technique of choice to take renal tissue is represented by ultrasound-guided PKB. A PKB is a quick, safe, and minimally invasive procedure that can be performed under local anesthesia. ^1,8 However, not all PKB are easy to perform successfully, especially when the kidney is difficult to localize, such as in cases of small kidneys, high up position in the renal loggia, or aberrant renal anatomy. ² Further, some conditions contraindicate the execution of PKB. Absolute contraindications are represented by patients who are uncooperative or have an abnormal body habitus, such as in cerebral palsy. Relative contraindications include coagulopathy, morbid obesity, uncontrolled hypertension, presence of a renal artery aneurism, solitary kidney, polycystic kidney, presence of multiple renal cysts, and small or ectopic kidney. ^{2 –4} Jeovah's Witness faith has also been described as a relative contraindication, because of the refusal to receive blood transfusions and to undergo certain surgical procedures on religious grounds. ²

When PKB is considered unsafe, a renal biopsy under direct vision is preferred. Any surgical approach is far more invasive than PKB but allows direct vision of the kidney, ensuring adequate sampling for pathological examination and the possibility to carry out hemostatic maneuvers under direct vision. One option is to resort to ORB, which is still performed in selected centers but carries a significant risk of postoperative morbidity and leads to prolonged hospital stay. A recent study performed on 115 patients who underwent ORB showed a mortality rate of 0.8% and major and minor complication rates of 6.1% and 27%, respectively. ⁵ Nowadays, a valid and minimally invasive alternative to ORB is represented by the laparoscopic approach, which spares the patient the pain and morbidity of a flank incision and shortens hospital stay. LKB warranted adequate diagnostic samples in all 40 cases in our cohort. These results are in accordance with those reported in other studies in literature, ^2,3 where almost all laparoscopic biopsies were successfully performed. Bleeding complications occurred in three of our patients, important data if we consider that 30.7% of our patients had bleeding disorders. Two patients reported bleeding from the trocar site with development of postoperative subcutaneous hematoma that was conservatively managed, without needing blood transfusions. One patient, instead, developed persistent postbiopsy renal bleeding that required embolization by interventional radiologists. The high success rate (100% in our series) and low risk of complications (7.5% in our series) of LKB, even in a high-risk population considered unsafe for PBK, demonstrate the effectiveness and reliability of the laparoscopic approach. LKB ensures the possibility to carry out hemostatic maneuvers for external bleeding, such as diathermocoagulation with bipolar forceps or application of fibrin sponges. In case of persistent hemorrhage, hemostatic stitches can be applied to the renal parenchyma. However, LKB cannot control bleeding into the urinary tract, as confirmed by our patient with grade IIIa complications, who required embolization to achieve hemostasis.

Both transperitoneal and retroperitoneal approaches have been described for LKB. ⁴ In our opinion, retroperitoneal approach guarantees more direct access to the kidney, especially in obese patients, and should be the standard technique. Further, in patients with cirrhosis with portal hypertension, it is mandatory to study the retroperitoneum on CT imaging to find the presence of retroperitoneal varicosities, which may increase the risk of surgical complications after the introduction of trocars.

Previous studies in the literature described laparoscopic biopsies performed with the aid of cup biopsy forceps, to yield adequate specimen ^2,3 ; in our series, we used an 18-gauge Trucut needle, as in the PKB, inserted under direct vision. Trucut needles provide good glomerular yield per core sample, require few cores for satisfactory tissue specimen, and cause a few major complications. In our opinion, the Trucut needle minimized the risks of bleeding from the renal parenchyma, allowing equally to take samples adequate for obtaining a pathological diagnosis.

The small incisions of the laparoscopic approach as compared with an open surgical biopsy allow to minimize the risks of wound infection and postoperative pain and to reduce the hospital stay. In the literature, the patients were discharged on average within 2 days after an LKB. ^{2 –4} Mean hospital stay from our series resulted in being unreliable, as most of our patients were nephrological inpatients with long hospital stays due to the management of renal failure and related comorbidities.

The major disadvantage of LKB is linked to the fact that it is a surgical procedure which requires general anesthesia, ⁹ and carbon dioxide (CO₂) insufflation, with the associated risks of CO₂ absorption, such as hypercarbia, acidosis, and gas emboli. ¹⁰ None of these complications was seen in our series. In three selected cases, our “ready-to-laparo” technique allowed us to perform the renal biopsy without even insufflating CO₂. The Trucut needle was inserted through a 10-mm incision made in correspondence of the kidney lower pole. In case of complications during the procedure, the Hasson trocar would have been introduced in the 10-mm incision and the classic laparoscopic approach would have been performed. In our three cases, no complications occurred, and the biopsies were successfully taken without proceeding to the classic LKB. In selected cases where the kidney lower pole is easily identified and there are no adhesions, this particular technique can represent an even more mini-invasive alternative to the classic LKB, sparing the patients the risks of CO₂ insufflation, particularly in patients with cardiac or pulmonary dysfunctions. ¹⁰

Other minimally invasive methods have been described in the literature to obtain renal tissue, such as the transjugular and the transurethral approaches. The transjugular approach, performed by a radiologist under fluoroscopic control, was described by Mal et al. ¹¹ The reported diagnostic yield of transjugular renal biopsy was 83%, and the complication rate was 10.5%, with fifteen cases of hematuria and six perirenal hematomas. Although interesting, this difficult technique exposes the patient to risks linked to radiation exposure and contrast medium injection and does not permit to achieve an accurate control of hemostasis. Moreover, to obtain an adequate specimen, a specific long-term experience of the operators is needed, reserving this technique to very few centers. The transurethral approach, instead, was reported by Leal. ¹² The biopsy was performed with an 18-gauge needle sheathed in an 8F catheter advanced into the renal pelvis, obtaining a transpelvic specimen. Although less invasive than LKB, this kind of biopsy does not allow a safe hemostasis control either. Further reports about this technique are lacking.

In the perspective of an even less invasiveness, the first cases of kidney biopsy with the retroperitoneal laparoendoscopic single-site surgery technique have recently been reported. ¹³ This new approach was considered safe and feasible showing better convalescence, less postoperative pain, and better cosmetic results compared with standard laparoscopy.

All these things considered, it seems that in patients unfit for PBK, the laparoscopic approach can be addressed as the first-choice alternative, being a safe, effective, and minimally invasive procedure.