Introduction

With the advent of advances in radiologic imaging, there is an increase in the number of diagnosed cases of Adrenal Incidentaloma (adrenal mass ≥ 1 cm diameter, discovered on imagining done for other organs). Prevalence of which is around 2% and noted to increase with age, affecting 4% of middle-aged and increases to 10% in elderly patients. Tumor of the adrenal gland more than 4 cm in diameter or if the mass enlarges by 1 cm during observation period is recommended to be surgically removed after thorough endocrine clearance. The concept of minimally invasive surgery changed the approach to adrenal tumors but did not changed the indications and goals of treatment [1,2,3,4]. Posterior retroperitoneal adrenalectomy has the advantage of direct approach without mobilizing adjacent structures justifying the shorter operative time and lower blood loss. The only drawback of this technique is the unfamiliar anatomic view of retroperitoneal space [5]. A study on learning curve for retroperitoneoscopic approach done by Barczynski and Walz showed that 20–25 cases should be done by an apprentice under the supervision of an experienced surgeon before being able to have a mean operative time of 90 min [6].

Anatomy

Right adrenal gland is mostly suprarenal and located in front of 12th rib, while the left is prerenally located in front of 11th and 12th ribs both lateral edges of vertebral column.

Posteriorly, it is in close proximity to diaphragmatic crus and lateral arcuate ligament. Anteriorly the right adrenal is lateral to inferior vena cava and the left adrenal is with adjacent organs such as spleen and the pancreatic tail.

Arterial supply: Superior adrenal artery from inferior phrenic artery.

  • Middle adrenal artery from aorta

  • Inferior adrenal artery from renal artery

Venous: each adrenal is usually drained by a single adrenal vein, the importance of handling this in tumors that secrete excess hormones.

  • Right vein is usually short (5–10 mm length) and drains to IVC (Fig. 1).

  • Left vein is longer (about 30 mm in length) empties to left renal vein.

  • Accessory veins in 5–10%.

Fig. 1
An illustration of the kidney. An arrow labeled R Adrenal vein drains to I V C points to a vein in the upper right kidney, while another label reads L adrenal vein drains to L renal. I V C is implanted in the lower left kidney.

Venous drainage of the adrenal gland

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Retroperitoneal Endoscopic Adrenalectomy

Retroperitoneoscopic approach was introduced by Martin Walz in mid-1990s as the more favorable technique for adrenal tumors. The advantage of less extensive dissection, and with bilateral adrenalectomy done in same position, is gaining popularity since its introduction [7].

Advantages—does not need extensive mobilization, is not affected by previous abdominal surgeries, same position for bilateral adrenalectomy, short surgery time. Tumors that are close to vena cava, this approach offers a direct access therefore less manipulation of vena cava avoiding injury [8].

Disadvantages—difficult to learn because there is a need for retroperitoneal view familiarity. This technique is not suitable for obese patients and large tumor because of limited working space.

Indications

Oncological Recommendations

  • Over 30 HU by enhanced CT with tumor size diameter of >4–5 cm and fast tumor growth without local invasion [1].

Endocrinological Indications

  • All cases of biochemically confirmed pheochromocytoma; Cushing’s syndrome, primary hyperaldosteronism, and hyperandrogenic syndrome [1].

Contraindications

  1. 1.

    Large adrenal lesions (>8–10 cm).

  2. 2.

    Unstable comorbidities.

  3. 3.

    Contraindications to anesthesia and pneumoperitoneum.

  4. 4.

    Previous retroperitoneal surgery.

Preoperative Preparations

  1. 1.

    Control of hypertension, correction of electrolyte abnormalities.

    1. (a)

      For pheochromocytoma, alpha blocker administration for 2–3 weeks preoperatively for heart rate normalization [1]. For potassium preparation, low sodium and high potassium diet with Spironolactone 100–400 mg/daily for few weeks [4].

    2. (b)

      If 1°aldosteronism is suspected, adrenal venous sampling is routinely performed for lateralization and patient started on spironolactone for at least 1 month preoperative. BP should be maintained below 150/100 mm Hg [2].

  2. 2.

    Evaluation and optimization.

  3. 3.

    Diagnostic criteria: Adrenal protocol CT, biochem marker screening for 1° aldosteronism, Cushing syndrome, and Phaeochromocytoma. Screening laboratory tests: like ECG, chest x-ray, electrolytes, clotting parameters, and blood type.

Instruments

  • Two 12 mm port.

  • Maryland dissector.

  • Harmonic scalpel.

  • One 5 mm port.

  • Clip applicator.

  • Suction/irrigation device.

  • 30° scope.

  • Curved scissors.

  • Specimen retrieval bag.

  • Atraumatic graspers .

  • Hook diathermy.

Prone or semi-jackknife position with the hips flexed (Fig. 2).

Fig. 2
An illustration of a body in a prone position, with an x-ray drawing of the rib cage, and three dots labeled 1 centimeter on the left side of the rib cage. A dotted line runs from the third dot to the bottom to the armpits.

Patient and port positions

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Surgical Technique

Walz’s technique—patient on prone jackknife position with bent hip joints at 90° angle to maximally open the space between 12th rib and iliac crest. Surgeon stands on the adrenal side to be removed and the assistant on the opposite side. The first 1.5 cm incision is placed approximately 1 cm inferior to the tip of 12th rib, followed by creation of retroperitoneal space by finger dissection. Two additional incisions were made at the posterior axillary line and between the first trocar site and mid-axillary line at the lower tip of 11th rib [2].These two 5 mm ports are placed about a palm breadth apart from the first port to avoid being too close that may interfere with instrument handling. CO2 insufflation can be set from 12 mm Hg to a maximum of 25 mm Hg, depending on how to achieve the best exposure for the adrenal gland [6, 9].

Exposure: The first step is visualization and mobilization of the upper pole of the kidney. Dissection is from superior pole from lateral to medial and inferior aspect of the adrenal.

For Right Adrenalectomy

Investing fascia is opened transversely at the upper pole until the IVC is identified and continues along the lateral edge to the right adrenal vein which is usually located posterolateral to IVC. Once identified can be clipped and may proceed to complete mobilization of the gland. Early transection of feeding arteries between Gerota’s fascia and psoas muscle results in tumor shrinkage and good bleeding control [4, 9].

For Left Adrenalectomy

The Gerota’s fascia is opened at the superior aspect of the kidney and dissection continued medially along the renal vein until the adrenal vein is identified, clipped with Hem-o-lock clips, and divided. There is identifiable feeding arteries which are often seen around renal pedicle and just above posts muscle can be ligated with a vessel sealing system [4, 9].

Importance of early ligation of adrenal central vein in Pheochromocytoma patients cannot be over-emphasized. This maneuver reduces the excessive catecholamine secretion thereby preventing intraoperative fluctuation of blood pressure [10].

Indications for Conversion

  • Uncontrolled hemorrhage.

  • Cardiac arrhythmias.

Conversion rate was noted to be 2–14% [11], Shen et al. reported that the significant independent predictive factors for conversion to open were tumor size >5 cm, BMI of ≥24 kg/m2, and Pheochromocytoma [12].

Complications

The most common intraoperative complications are bleeding from adrenal and renal vein and vena caval injuries while the postoperative complications are retroperitoneal hematoma and hyponatremia [11].

  1. 1.

    Neuromuscular pain—noted in 9% in one of the largest series done by Walz et al. This is secondary to subcostal injury during trocar insertion but is only temporary [13].

  2. 2.

    Wound infection especially in patient’s with Cushing’s syndrome.

Postoperative Care

Hypotension is a possible problem postoperatively because of catecholamine decrease leading to vasodilatation reducing the cardiac output. Cortisol, ACTH concentration, and serum electrolyte are requested to assess if the patient will require steroid coverage after surgery. Patients requiring steroid replacement are observed for 72–96 h prior to discharge [4]. Steroid replacement is mandatory for patients post-surgery for Cushing’s syndrome for several months until adequate functioning of the remaining adrenal gland. Patients are allowed to ambulate, start on diet, and require minimal analgesic [11]. Diagnostics such as full blood count and electrolytes may be done as clinically indicated. Periodic glucose monitoring for Pheochromocytoma patients.

Practical Tips and Tricks [14]

  • Complication rate—0–15% for unilateral, rises to 23% for bilateral.

  • Male sex and high BMI correlate significantly with duration of OR.

Position

  • 90° angle between spine and legs should be obtained to optimize distance between rib and iliac crest.

Trocar Position

  • Correct and planned angle and position to avoid clashing of instruments and hand fatigue. If 11th rib is noted to be long, the trocar should be adjusted to more cranial position to allow a better degree of freedom for movement.

CO2 Insufflation Pressure

  • Can be increased to max of 25 mm Hg and can be adjusted according to the anatomy/working space of the patient. This helps to create good working space and in small vessel bleeding tamponade; air embolism is a possibility but none was reported even with the largest series of Walz et al. [8]

Dissection

  • Early identification of landmarks is crucial [8] It is best to start at the upper pole of the kidney, conducted clockwise starting from 3 to 9 o’clock on the right and counterclockwise 9–3 o’clock on the left.

Choice of Patient

  • for early part of surgical experience, do not go for tumors larger than 4 cm, should be smaller and avoid patients with BMI of >35 because these patients have dense retroperitoneal fat adherent to capsule of the kidney, making dissection difficult.