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Keywords:

  • Classification;
  • lymphadenectomy;
  • para aortic;
  • surgical technique;
  • vascular anomalies

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Definition of systematic (complete) para-aortic node dissection
  5. Classification system for para-aortic node assessment
  6. Technique of systematic (complete) para-aortic node dissection
  7. Anatomical vascular anomalies/variations
  8. Conclusion
  9. Disclosure of interests
  10. Contribution to authorship
  11. Details of ethics approval
  12. Funding
  13. Acknowledgement
  14. References
  15. Supporting Information

Please cite this paper as: Pomel C, Naik R, Martinez A, Ferron G, Nassif J, Dauplat J, Jeyarajah A. Systematic (complete) para-aortic lymphadenectomy: description of a novel surgical classification with technical and anatomical considerations. BJOG 2012;119:249–253.

The clinical indications for a complete para-aortic lymphadenectomy in the surgical management of gynaecological malignancies remain controversial. The debate on complete para-aortic node dissection is hindered by the absence of an identifiable and accepted definition for the procedure of systematic (complete) para-aortic node dissection. In this paper we propose a classification of para-aortic lymphadenectomy. We have identified and imaged the most common and rare para-aortic vascular anomalies that we have encountered. An understanding of the anatomical anomalies in this area also provides a useful reference for the surgical technique that is adopted in order to ensure the completeness of excision.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Definition of systematic (complete) para-aortic node dissection
  5. Classification system for para-aortic node assessment
  6. Technique of systematic (complete) para-aortic node dissection
  7. Anatomical vascular anomalies/variations
  8. Conclusion
  9. Disclosure of interests
  10. Contribution to authorship
  11. Details of ethics approval
  12. Funding
  13. Acknowledgement
  14. References
  15. Supporting Information

The clinical indications for a systematic para-aortic lymphadenectomy in the surgical management of gynaecological malignancies are highly debatable. Despite being routinely performed in many international centres for early-stage ovarian/endometrial cancers and advanced-stage ovarian/cervical cancers, there is very little published evidence of therapeutic benefit. The UK’s National Institute for Health and Clinical Excellence (NICE) recently published the outcomes of it’s review on the management of ovarian cancer, and identified only one previous randomised controlled trial on systematic (complete) para-aortic lymphadenectomy in early-stage ovarian cancer, which showed no benefit to survival.1 As a result, they stated that it should not be performed as a routine procedure in the management of these cases, although it did recommend retroperitoneal nodal assessment to guide/determine the need for adjuvant chemotherapy treatment.

Similarly, for advanced-stage ovarian cancer, only one randomised controlled trial has previously been performed, again showing no evidence of benefit in overall survival, but suggesting a small but statistically significant improvement in progression-free survival.2 This investigation is currently being repeated by two studies: the German AGO Group as part of the LION study and the CARACO study in France. For endometrial and cervical cancers, there are no previous randomised controlled trials investigating survival outcomes for systematic (complete) para-aortic node dissection, although non-randomised studies suggest that it may be of value in guiding adjuvant/definitive chemotherapy/radiotherapy treatment.3

Although accepting the lack of clear evidence of benefit and the urgent need for well-designed prospective studies, the current debate on systematic (complete) para-aortic node dissection is hindered by the absence of an identifiable and accepted definition for the procedure of systematic (complete) para-aortic node dissection. In addition, although there is common usage of the term para-aortic node sampling, it is unclear as to the precise meaning of this terminology in the absence of an identifiable classification system. Recent publications have proposed a classification system for the procedure of pelvic node dissection, but these publications do not address the para-aortic area.

This article presents a definition of a systematic (complete) para-aortic node dissection, supported by photographs illustrating the degree to which the nodal tissues surrounding the abdominal vessels should be resected to qualify as ‘systematic and complete’. In addition, we propose a classification system with which to categorise lesser degrees of para-aortic node dissection in addition to other non-excisional forms of para-aortic node assessment. Finally, we describe the technique of performing systematic (complete) para-aortic node dissection with special emphasis on the variations in local anatomy one may expect to encounter in an attempt to avoid/reduce the risk of significant injury to the major vessels when performing the procedure, and to ensure the completeness of excision.

The value of addressing these objectives is to facilitate continued debate and communication, to encourage further research on the clinical value of systematic (complete) para-aortic node dissection, to advance surgical training of these procedures and to encourage their appropriate performance in select cases.

Definition of systematic (complete) para-aortic node dissection

  1. Top of page
  2. Abstract
  3. Introduction
  4. Definition of systematic (complete) para-aortic node dissection
  5. Classification system for para-aortic node assessment
  6. Technique of systematic (complete) para-aortic node dissection
  7. Anatomical vascular anomalies/variations
  8. Conclusion
  9. Disclosure of interests
  10. Contribution to authorship
  11. Details of ethics approval
  12. Funding
  13. Acknowledgement
  14. References
  15. Supporting Information

Systematic (complete) para-aortic lymphadenectomy is defined as the complete removal of all fat and nodal tissues surrounding the aorta, inferior vena cava (IVC) and renal vessels from the left renal vein cranially to the midpoint of the common iliac vessels caudally. Evidence of complete removal should facilitate the full and complete visualisation of the adventitia of each of the aforementioned vessels, in addition to the full exposure of the anterior common vertebral ligament, anterior and lateral aspects of the vertebral bodies, psoas muscles and anterior sacrum. It includes the separation and removal of all tissues lying between the arterial and venous vessels, and the clear identification of the origin/root of the ovarian vessels, inferior mesenteric artery, lumbar vessels and accessory vessels.

Classification system for para-aortic node assessment

  1. Top of page
  2. Abstract
  3. Introduction
  4. Definition of systematic (complete) para-aortic node dissection
  5. Classification system for para-aortic node assessment
  6. Technique of systematic (complete) para-aortic node dissection
  7. Anatomical vascular anomalies/variations
  8. Conclusion
  9. Disclosure of interests
  10. Contribution to authorship
  11. Details of ethics approval
  12. Funding
  13. Acknowledgement
  14. References
  15. Supporting Information
  • (A)
     Systematic para-aortic node dissection
    • A1
       Complete (includes infrarenal and suprarenal up to the coeliac trunk to midpoint of common iliac vessels).
    • A2
       Infrarenal (as above, but does not include suprarenal dissection).
    • A3
       Infra-inferior mesenteric artery (IMA) (as above, but does not include dissection above IMA).
  • (B)
     Para-aortic node sampling
    • B1
       Extensive (includes para-aortic areas, but does not allow full visualisation of structures listed above, that is adventicia of vessels, renal vessels, anterior common vertebral ligament, psoas muscles and sacrum).
    • B2
       Minimal (includes limited para-aortic areas, and does not allow full visualisation of structures listed above).
  • (C)
     Non-excisional assessment
    • C1
       Palpation (direct), following full exposure of para-aortic areas.
    • C2
       Palpation (indirect), transperitoneal without any exposure.
    • C3
       Radiological assessment by positron emission tomography (PET)/computed tomography (CT), CT or magnetic resonance imaging (MRI).

Nodal count is considered to be inaccurate in classification as it depends on other factors, including pathological assessment.

Technique of systematic (complete) para-aortic node dissection

  1. Top of page
  2. Abstract
  3. Introduction
  4. Definition of systematic (complete) para-aortic node dissection
  5. Classification system for para-aortic node assessment
  6. Technique of systematic (complete) para-aortic node dissection
  7. Anatomical vascular anomalies/variations
  8. Conclusion
  9. Disclosure of interests
  10. Contribution to authorship
  11. Details of ethics approval
  12. Funding
  13. Acknowledgement
  14. References
  15. Supporting Information

All patients undergo bowel preparation consisting of 5 days of low-fibre diet and one sachet of Picolax® (Ferring Pharmaceuticals Ltd, West Drayton, UK) 2 days prior to surgery. The patient is laid supine or in the modified Lloyd Davis position (if the procedure is part of ovarian cancer debulking), with a Foley catheter, following usual antibiotic prophylaxis. A vertical medial incision is extended to the xyphisternum. Self-retaining Bookwalter retractors allow excellent exposure and access, and free both the surgeon and the assistant during the procedure. The caecum and the right side of the colon in addition to the small bowel mesentery and the duodenum are mobilised by incising the peritoneal layer at the level of the right common iliac artery, medially crossing the midline up to the level of the fourth part of the duodenum. The loose avascular underlying tissues are gently dissected. This ‘Kocher’s manoeuvre’ allows the bowel to be laid onto the lower thorax, protected with a large damp swab, or placed into a bowel bag (Figure S1).

  • 1
     The left renal vein is identified.
  • 2
     The right ureter is freed medially.
  • 3
     The left ureter is identified medially behind the inferior mesenteric vein, above the level of the inferior mesenteric artery. These steps allow the lateral aspects of the vertebral bodies and the psoas muscle to be clearly identified bilaterally.
  • 4
     The fatty tissues anterior to the aorta are separated/divided, exposing the adventitia of the vessel along its full length and including the right common iliac artery, mobilising the nodal tissues laterally towards the left and right of the artery.
  • 5
     The nodal tissues that have been mobilised towards the left of the aorta are dissected, starting cranially, without undue traction or mobilisation of the aorta, in order to avoid injury to the posterior lumbar vessels. The left para-vertebral sympathetic plexus is identified posteriorely.
  • 6
     The nodal tissues along the right of the aorta are then dissected, allowing visualisation of the anterior common vertebral ligament. This dissection is continued to expose the left aspect of the IVC down to the level of the right common iliac artery. As the right common iliac artery has been properly isolated and dissected, this will ease the approach of the anterior aspect of the lower part of the vena cava including the small anterior branches that are commonly encountered in this area.
  • 7
     The dissection is continued to include the right side of the IVC with respect to the right paravertebral sympathetic plexus.

The ovarian vessels can be dissected and either preserved or ligated at the level of the great vessels. We recommend the use of clips or proper ligation when a large lymphatic duct has been identified.

The technique described above is identical when managing bulky/confluent nodal masses, except that vascular slings are placed prior to the dissection of the bulky disease. These slings are applied around the IVC at three locations: (1) suprarenal; (2) infrarenal; and (3) around the renal veins (as illustrated in Figure 1). These slings can be used to cut off the blood supply to the relevant areas of the vena cava during the dissection, to allow repair of any vessel injuries that may occur whilst minimising blood loss and major haemorrhage. The use of a steep Trendelenburg position and ensuring that the patient is kept under-hydrated during the procedure are both highly effective methods for reducing venous pressure within the vena cava, and also help to reduce blood loss during the dissection.

image

Figure 1.  Perioperative management of para-aortic lymphadenectomy.

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Vascular injuries are managed in the usual manner, consisting firstly of pressure on the bleeding area. This is usually effective after 2–5 minutes, and will if required allow the insertion of sutures using 5.0 double-bladed monofilament. In the absence of vascular slings, one can consider the use of aortic clamps even for venous bleeding as this will contribute significantly by reducing the haemorrhage until the sutures have been inserted. Further bleeding/oozing from the sutured vessel can be effectively managed by using the many haemostatic agents currently available (Evicel®, OMRIX Biopharmaceuticals Ltd, Kiryat, Israel; FloSeal®, Baxter, Newbury, UK; Fibrillar®, Johnson & Johnson Medical Limited, Livingston, UK; Nu-knit®, Johnson & Johnson Medical Limited, Livingston, UK; or Surgicel®, Johnson & Johnson Medical Limited, Livingston, UK).

The technique can be applied in virtually all cases, including patients that are obese and also following chemotherapy, radiotherapy or concomitant chemo-radiation therapy. Associated morbidity ranges from 2 to 13% of cases.4 Most of these can be considered to be minor, such as lymphocysts and lymphoedema. Neurological morbidities are rare. In their study, Benedetti et al.2 showed that the number of intraoperative complications was similar in the two arms. Systematic lymphadenectomy had greater perioperative and late morbidity. Most of the difference in morbidity resulted from the formation of lymphocysts and lymphoedema. Massive intraoperative haemorrhage is clearly a major risk with this type of surgery, with the resultant morbidity and potential mortality. From our experience, complete dissection and isolation of the major vessels and their divisions is key to avoiding significant bleeding. In addition it facilitates better control of the operating field should vessel injury occur.

Anatomical vascular anomalies/variations

  1. Top of page
  2. Abstract
  3. Introduction
  4. Definition of systematic (complete) para-aortic node dissection
  5. Classification system for para-aortic node assessment
  6. Technique of systematic (complete) para-aortic node dissection
  7. Anatomical vascular anomalies/variations
  8. Conclusion
  9. Disclosure of interests
  10. Contribution to authorship
  11. Details of ethics approval
  12. Funding
  13. Acknowledgement
  14. References
  15. Supporting Information

During 15 years of performing para-aortic node dissection for ovarian, cervical and endometrial cancers, we have identified and imaged the most common and rare para-aortic vascular anomalies that we have encountered. Whereas some of these anomalies were identified on preoperative imaging, many were identified intraoperatively.

The mechanisms that lead to vascular abnormalities come from their embryological development. Vascular abnormalities can occur in the vena cava, renal, azygos, pre-vertebral and ascending lumbar venous systems, as well as the renal arteries. Being informed of rare anatomical abnormalities may avoid the risk of damaging branches of the greater vessels.5 During embryologic development, the kidney arterial supply originates from the aorta at successively higher levels as the kidney ascends from the pelvis. Renal arterial variants, including accessory renal arteries, are quite common, with prevalence as high as 30–40%. Right renal arteries are classically described as passing posterior to the IVC. CT scans report as many as 5% of pre-caval renal arteries.6 The naming of renal artery variations remains controversial. Supplementary or accessory renal arteries enter the kidney through the hilum, whereas aberrant arteries enter the kidney at the polar level (so-called superior or inferior polar arteries; Figure S2a,b). Venous anomalies occur in about 3% of cases. They include: left-sided IVC (situs inversus); double vena cava; retroaortic renal vein; circum aortic renal vein; and interrupted IVC (Figures S3 and S4a).7 There are also some rare cases of unique ascending renal arteries (Figure S4b). Care must be taken with the right renal artery, which can be injured below the level of the left renal vein, between the aorta and the vena cava (Figure S4c). Brener and colleagues8 reviewed venous anomalies found during abdominal aortic reconstructions between 1959 and 1973. They observed 31 anomalies of the IVC or renal veins, resulting in 11 complications. The posterior left renal vein and the duplication of the IVC are the most common venous anomalies (Figures 2 and S5). Of the above anomalies, the circumaortic renal collar and the posterior left renal vein pose the greatest threat, as the posterior veins may be easily injured during dissection prior to the placement of an aortic cross clamp or vascular slings. Meticulous attention to detail during the dissection of the infrarenal aorta and common iliac arteries is essential to avoid haemorrhage from anomalous veins. Less than 0.3% of the general population have horseshoe kidneys, which are seen in approximately 1 in 300 pyelographies. The vessels may have varied origin from the aorta at the level of T12 to the internal iliac artery at the lower levels. The total number of vessels may vary from four to seven, and the vessel size ranges from 2 to 8 mm (Figure S6).9

image

Figure 2.  Duplication of vena cava. Note the right common iliac vein connected to the left inferior vena cava.

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The anterior aspect of the aorta is the only area that is not affected by any anatomical abnormality or variation. Therefore, after careful imaging review, we strongly advise that the para-aortic node dissection is begun on the anterior aspect of the aorta, as recommended by Zivanovic et al.10 The para-aortic node dissection is thus divided into two parts: the left para-aortic dissection and the right para-aortic dissection. The latter dissection includes the dissection of the tissues between the aorta and the vena cava, and pre- and retrocaval and right paracaval areas.

Conclusion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Definition of systematic (complete) para-aortic node dissection
  5. Classification system for para-aortic node assessment
  6. Technique of systematic (complete) para-aortic node dissection
  7. Anatomical vascular anomalies/variations
  8. Conclusion
  9. Disclosure of interests
  10. Contribution to authorship
  11. Details of ethics approval
  12. Funding
  13. Acknowledgement
  14. References
  15. Supporting Information

This article provides a rational definition of systematic (complete) para-aortic node dissection and a workable classification system, in an attempt to facilitate discussions and generate future research studies on the clinical value of para-aortic node assessment. An understanding of the anatomical anomalies in this area also provides a useful reference to the surgical technique that is adopted to help minimise the risk of injury to the major vessels, and to ensure the completeness of excision.

Contribution to authorship

  1. Top of page
  2. Abstract
  3. Introduction
  4. Definition of systematic (complete) para-aortic node dissection
  5. Classification system for para-aortic node assessment
  6. Technique of systematic (complete) para-aortic node dissection
  7. Anatomical vascular anomalies/variations
  8. Conclusion
  9. Disclosure of interests
  10. Contribution to authorship
  11. Details of ethics approval
  12. Funding
  13. Acknowledgement
  14. References
  15. Supporting Information

CP and RN conceived and designed the experiments. CP, GF and JD performed the experiments. CP and RN collected and assembled the data. CP, JD and RN analyzed the data. CP, RN, JN, AM, GF, JD and AJ contributed reagents, materials or analysis tools for the study. CP, RN, JN and AJ wrote the paper.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Definition of systematic (complete) para-aortic node dissection
  5. Classification system for para-aortic node assessment
  6. Technique of systematic (complete) para-aortic node dissection
  7. Anatomical vascular anomalies/variations
  8. Conclusion
  9. Disclosure of interests
  10. Contribution to authorship
  11. Details of ethics approval
  12. Funding
  13. Acknowledgement
  14. References
  15. Supporting Information

Supporting Information

  1. Top of page
  2. Abstract
  3. Introduction
  4. Definition of systematic (complete) para-aortic node dissection
  5. Classification system for para-aortic node assessment
  6. Technique of systematic (complete) para-aortic node dissection
  7. Anatomical vascular anomalies/variations
  8. Conclusion
  9. Disclosure of interests
  10. Contribution to authorship
  11. Details of ethics approval
  12. Funding
  13. Acknowledgement
  14. References
  15. Supporting Information

Figure S1. Installation.

Figure S2. (A) Inferior polar renal arteries. (B) Double right polar arteries with inferior polar vein.

Figure S3. Left retroaortic renal vein.

Figure S4. (A) Circum left renal vein and ascending left renal artery. (B) Ascending left renal artery at the level of the inferior mesentery artery (IMA). (C) Right renal artery below the level of the left renal vein.

Figure S5. Duplication of vena cava associated with precaval renal arteries.

Figure S6. Horseshoe kidney with slings around kidney, ureters and vessels.

FilenameFormatSizeDescription
BJO_3171_sm_FigS1.pdf362KSupporting info item
BJO_3171_sm_FigS2a.pdf249KSupporting info item
BJO_3171_sm_FigS2b.pdf191KSupporting info item
BJO_3171_sm_FigS3.pdf121KSupporting info item
BJO_3171_sm_FigS4a.pdf210KSupporting info item
BJO_3171_sm_FigS4b.pdf171KSupporting info item
BJO_3171_sm_FigS4c.pdf224KSupporting info item
BJO_3171_sm_FigS5.pdf176KSupporting info item
BJO_3171_sm_FigS6.pdf223KSupporting info item

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