Retroperitoneoscopic adrenalectomy: indications and technical considerations

Introduction

While a minimally invasive approach to adrenal surgery has become the preferred method, which particular method to choose remains at the discretion of the operating surgeon. Two surgical methods to minimally invasive adrenalectomy currently exist: transabdominal laparoscopic and posterior retroperitoneoscopic (1). These minimally invasive approaches have been widely adopted due to their shorter length of stay, decreased post-operative pain and earlier return to baseline activity (2). Laparoscopic adrenalectomy was first described in 1992 in Japan, and the retroperitoneal approach was introduced shortly after, in 1995 (2). Since then, it has slowly been adopted by select, high-volume endocrine surgery centers. Pioneers of this technique have been able to standardize the approach to gain wider acceptance within the field of endocrine surgery.

Indications

The retroperitoneoscopic approach is indicated for biochemically functional or large, benign adrenal neoplasms (3,4). Adrenocortical carcinomas, or tumors which appear to be suspicious for carcinoma (based on imaging characteristics) can be approached laparoscopically if they are less than 6 cm (according to most authors recommendations) (3-6). If there is concern for invasion into surrounding structures during the operation, then conversion to an open approach is recommended. Of note, the retroperitoneoscopic approach is safer and faster than the transperitoneal approach for large pheochromocytomas (7). Studies also suggest that this approach is safe and feasible for patients with metastatic tumors isolated to the adrenal gland, and may be particularly favorable for patients with a high risk for significant intraperitoneal adhesions (8,9). Laparoscopic surgery continues to push the envelope and new literature demonstrates successful removal of metastatic tumors and pheochromocytomas.

Approaches to retroperitoneal adrenalectomy have expanded to include mini-laparoscopic and even single-port robotic-assisted adrenalectomies, which may circumvent the risk for venous hemorrhaging, a dangerous complication of the laparoscopic approach, and reduce narcotic use post-operatively (10). However, due to the increased cost and limited data on the outcomes of these procedures, posterior retroperitoneoscopic adrenalectomy remains a mainstay approach to treatment of adrenal tumors.

Relative contraindications to this particular approach include the following: extremely large tumors, malignant tumors with invasion into surrounding structures, or inadequate working space between the 12^th rib and posterior superior iliac crest (PSIC). The patient’s inability to tolerate general anesthesia or lay prone for the procedure pose as strict contraindications to the retroperitoneal approach (Table 1).

Retroperitoeneal approaches can be performed laterally or posteriorly (Figure 1). The posterior retroperitoneoscopic approach (PRA) can be utilized in adrenal masses in which the patient’s body habitus allows. The distance between the 12^th rib and the iliac crest should be one handsbreathe. Ideally, a patient’s BMI (body mass index) should be below 35, however, there is no precise cutoff for BMI. Relative contraindications to the approach include a BMI >40 and tumors >7 cm, as the patient’s position can increase intra-abdominal pressure. Additionally, it is more difficult to convert to an open adrenalectomy in PRAs than in lateral retroperitoneoscopic approaches (10,15). Reasons for conversion to the transabdominal approach include patient size (BMI >45), which can cause compression of the retroperitoneum by abdominal organs when placing the patient in the prone position (15,16), and inability to tolerate high insufflation pressures.

Figure 1 Algorithm for PRA. PSIC, posterior superior iliac crest; PRA, posterior retroperitoneoscopic approach.

PRA has several advantages over the lateral retroperitoneoscopic approach. This approach offers the unique ability to avoid repositioning patients in the case of a bilateral adrenalectomy. It also offers an undisturbed plane for the surgeon without the risk of encountering previous scar tissue in patients with prior abdominal surgical procedures. Furthermore, direct access to the retroperitoneoscopic space allows the surgeon to approach the adrenal without manipulation of the intestine, or mobilization of the colon. This reduces the risk of post-operative ileus, and markedly decreases the hospital length of stay with these procedures (2,3).

Technical considerations

PRA carries a steeper learning curve than the transabdominal laparoscopic approach. The retroperitoneal space can appear unfamiliar when approaching the adrenal gland posteriorly. The learning curve reported in the literature is on average 30 cases, if performed by an experienced laparoscopic surgeon (2).

Technical considerations rely heavily on patient positioning. Patients are positioned in a jackknife position with a 90-degree angle between the hip and knee joint. Due to the limited working space, the patient ideally is positioned in a way to maximize the distance from the iliac crest to the costovertebral angle.

Marking anatomical landmarks prior to incision can be helpful for operative planning. The authors recommend identifying the lateral border of the paraspinous muscles, the inferior margin of the 12^th rib, as well as the PSIC. The first incision should be placed below the angle of the 12^th rib, with allotment for three trocars across the back. The incision should allow your finger to help with blunt dissection and be able to fit a 10 mm trocar. Entrance into the retroperitoneal space is accomplished by blunt dissection with a Kelly clamp or sharp dissection with scissors. Once you have entered the retroperitoneal space, perform a finger sweep.

Two additional five mm ports should be placed under finger guidance just lateral to the paraspinous muscles and below the tip of the 11^th rib. Once the 5 mm ports are inserted a ten mm balloon port is placed. The trocars are positioned cranially at a slight angle to allow for full motion of the instruments. We recommend using a 30-degree laparoscope. Creating the retroperitoneal space can be the most challenging task. A combination of blunt and heat device is recommended to develop the plane below the diaphragm. The fatty tissue encountered should be pushed down and Gerota’s fascia should be opened to identify the kidney.

Our ideal angle to approach the dissection is to start at the superior pole of the kidney. One blunt open jawed grasper should be used to push down the kidney; approaching the superior pole of the kidney will allow the inferior aspect of the adrenal gland to come into view. The small arterial vessels feeding the adrenal gland can be divided using an electrocautery device. Dissection should continue in this plane, leaving the superior attachments to of the adrenal gland intact.

On the right side, when lifting the adrenal gland up, the inferior vena cava will come into view. The adrenal vein should be identified postero-laterally. On the left side, the adrenal vein can be identified in the space between the medial aspect of the gland and the phrenic vein. This branch is normally medial to the upper pole of the kidney. Once the adrenal vein is isolated, it is recommended that it is circumferentially dissected and ligated using heat device or application of clips. The dissection is then continued medially, laterally and cranially; the adrenal vein stump can be used as the grasping handle. Once the entirety of the adrenal gland is dissected free it should be extracted in a specimen bag.

Technical considerations when attempting the PRA approach include using high-pressure CO₂ insufflation (our preferred pressure is 25 mmHg). The retroperitoneal space can tolerate these higher insufflation pressures without causing any cardiovascular changes to the patient. This not only creates additional space, which is needed due to the limited working space in this approach, but also tamponades minor bleeding from small arterioles. Prior to closing, the pressure should be decreased and an additional check for hemostasis should be performed. The higher pressure used can also cause subcutaneous emphysema of the neck and chest. This tends to be asymptomatic and should not alter hospital length of stay.

Potential complications of this approach include pneumothorax during placement of trocars or diaphragm dissection. Additionally, violation of the peritoneal cavity can lead to damage to the spleen or tail of the pancreas on the left or the liver on the right.

The retroperitoneoscopic approach is a valuable approach to adrenal surgery. Despite its challenging learning curve, the standardization of steps and direct access to the tumor make it an excellent option for minimally invasive surgeons.

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the Guest Editor (Robert Sutcliffe) for the series “Laparoscopic Adrenalectomy” published in Laparoscopic Surgery. The article has undergone external peer review.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://ls.amegroups.com/article/view/10.21037/ls-21-24/coif). The series “Laparoscopic Adrenalectomy” was commissioned by the editorial office without any funding or sponsorship. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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