Adrenal anatomy . Note the variances in left- and right-sided venous drainage.
The venous drainage of the adrenal gland is less complex with a single vessel draining the entire gland . The course of the vein varies based on laterality with the right adrenal vein draining directly into the inferior vena cava and the left adrenal vein connecting to the IVC by way of the inferior phrenic vein to the left renal vein.
The adrenal gland is grossly divided into the medulla and the cortex. The cortex is largely comprised of lipids giving it a yellow color. The cortex makes up the exterior portion of the gland and accounts for the large majority of the gland’s volume. It is subdivided into three zones: the zona glomerulosa, the zona fasciculata, and the zona reticularis. The zona reticularis reaches its final maturity late in childhood. The zona glomerulosa produces mineralocorticoid (aldosterone, 11-doxycorticosterone). The zona fasciculata and the zona reticularis produce glucocorticoids (cortisol) and the adrenal androgens (didehydroepiandrosterone (DHEA), androstenedione, testosterone, estrogen). The medulla comprises a smaller area, only 10–20 % of the total gland. Its cells are derived from neural crest cells and secrete the catecholamines norepinephrine and epinephrine .
The lymphatics are divided into two plexuses, one in the medulla and one just under the capsule . The left adrenal lymphatics drain to the nodes near the left renal artery, while the right adrenal lymphatics drain to the periaortic lymph nodes. Innervation to the adrenal gland is primarily composed of splanchnic nerves to the medulla, while the cortex lacks any identifiable innervations.
Indications/Selection of Patients
Almost all adrenal tumors are treated with surgical removal . Congenital adrenal hyperplasia is the only primary hyperfunctioning disorder for which medical therapy is indicated over surgical excision. Bilateral adrenal hyperplasia is much less responsive to surgery than its unilateral counterpart, and selective venous catheterization is used to predict response to surgery. Bilateral hyperplasia is managed medically with spironolactone, and unilateral hyperplasia is treated surgically with unilateral adrenalectomy.
Pheochromocytomas are initially treated with alpha-blockers to manage blood pressure prior to surgical intervention, while definitive treatment requires removal of the adrenal gland . In the pediatric patient, extensive adrenocortical carcinoma is often resected en bloc along with lymph nodes, while minimally invasive techniques predominate for less extensive disease .
For adrenal incidentalomas , surgery is the treatment of choice if the mass is enlarging or functioning. In adults, resection is typically indicated for masses greater than 5 cm, but in the pediatric population, some surgeons advocate resection without regard to size. The pediatric population is also unique in that more than 90 % of adrenal masses are neuroblastomas . In neuroblastoma, treatment is resection, although initially unresectable tumors may become resectable following chemotherapy.
The main techniques for laparoscopic adrenalectomy are the lateral transabdominal and the posterior retroperitoneal approach . Left adrenalectomy and right adrenalectomy are two distinct procedures.
Transabdominal Lateral Approach
The transabdominal lateral approach is more commonly used in the pediatric population. It is performed with patient in the lateral decubitus position with the operative side up allowing gravity to assist in exposure of the adrenal glands. Prior to placing the patient on their side, the stomach and bladder are decompressed with an orogastric tube and Foley catheters. A kidney rest is placed in the lumbar area, and the bed is flexed at the level of the iliac crest to maximally open the space between it and the costal margin for trocar insertion. The bed is placed in a slight reverse Trendelenburg position. The superior arm is supported on pillows on top and the opposite arm is secured to arm board. An axillary roll is placed and all bony prominences are protected. Next, the bean bag is firmed and the patient is secured, again ensuring appropriated padding of all pressure points. The skin is then prepped and draped in the standard fashion with enough skin exposed to allow open laparotomy if necessary.
Three to four trocars are placed in a subcostal position on the side of the adrenal gland to be extracted, starting with a 5-mm umbilical port placed under direct vision. The carbon dioxide (CO2) insufflation begins at a low flow rate with maintenance of intra-abdominal pressure of 10–12 mmHg. A 30° camera should be used, if available. Under direct vision, a 3-mm or 5-mm port should be placed in the upper midline, close to the xiphoid process (Fig. 45.2). A third port (5-mm) should be placed laterally, close to the costal margin. An additional accessory port is often used on the right for either liver retraction or improved exposure.
Laparoscopic port placement for left sided adrenalectomy. Anterior and lateral views are shown.
It has also been described by Cameron et al. to use a 10- or 12-mm incision into the flank at the midclavicular line, two fingerbreadths below the left costal margin . Dissection is carried down to the fascia, which is elevated between two Kocher clamps, and the peritoneal cavity is entered with a Veress needle. After a successful leak test, the peritoneal cavity is insufflated and a 10- or 12-mm trocar is placed at the Veress site. The 10-mm cannula is used in order to remove the specimen through the cannula or the incision. A specimen bag is necessary due to the potential of malignancy. Working ports (5-mm or 3-mm) are placed in a fashion to triangulate the lesion with as much distance between ports as possible depending on the patient’s size. Often, the peritoneal attachments to the colon must be divided in order to place the most posterior cannula.
In a right adrenalectomy , exposure is improved by dividing the right triangular ligament of the liver, including the most lateral and posterior attachments to the peritoneum. The fourth trocar should be placed in the epigastrium and used as a retractor to elevate the right lobe of the liver. During mobilization of the right hepatic lobe, always recognize the proximity of the inferior vena cava. Laparoscopic ultrasound can assist with this, as well as identifying the borders of the liver, kidney, and major vessels to allow for safe and expeditious dissection.
The retroperitoneum is then incised along the inferior vena cava allowing exposure to the adrenal gland and its vessels. The medial border of the inferior vena cava is carefully exposed, looking for the right adrenal vein at the superior medial border of the adrenal, remembering that this vein is typically broad and short and enters the vena cava slightly posteriorly . Three clips should be used, with distal-most clip at the edge of the vena cava. Clipping the vein first is especially important in cases of pheochromocytomas.
Once the right adrenal vein has been clipped and divided, dissection continues with use of monopolar hook electrocautery to mobilize the medial portion of the adrenal gland. By dissecting from medial to lateral and inferior to superior, the superior pole of the kidney can be used as a dissection plane through the Gerota fascia, and the dissection can progress in a direction away from any anatomic danger areas (inferior vena cava and renal vein) . Visible vessels, including the inferior phrenic vessel which is commonly seen at the superior and lateral border of the gland, are clipped. Before specimen extraction, the operative field is inspected for hemostasis. The adrenal gland is then placed within a bag and extracted without morcellation.
Division of the lienocolic ligament up to the level of the gastric fundus improves exposure of the left adrenal gland by allowing the spleen to fall medially, pulling the tail of the pancreas with it. The left colon is also mobilized medially. Laparoscopic ultrasound can be used to verify the borders of the adrenal, kidney, and pancreas. It is important to note that the dissection plane should be relatively avascular and that it is relatively easy to mistake the tail of the pancreas for the adrenal gland.
With small tumors, first dissect the inferior and medial aspect of the adrenal remaining close to the gland until the vein is ligated with endoscopic clips. A right-angle dissector facilitates this exposure. It is important to remember that on the left, this should be done early in the operation after locating it entering the renal vein. Afterward, the gland is then carefully dissected free from the diaphragmatic attachments superiorly, the kidney on its inferior and lateral aspects, and medially from the midline structures. The inferior phrenic artery is frequently encountered along the superior edge of the adrenal and should be sought and ligated with clips and divided . The dissection and extraction then occur in a similar fashion. For large tumors, early identification of the vein may be difficult and mobilization of the gland inferiorly and laterally is often helpful.