Lymphatic Drainage of the Pelvis and Perineum

Introduction

• Lymphatic drainage is complex and often overlooked.
• Focus: Simplifying the pattern and highlighting exceptions.
• Key points:
  • All lymph from below waist drains via the thoracic duct.
  • Lymph above waist drains via right lymphatic duct or thoracic duct.
  • Thoracic duct joins venous system at left venous angle.

Lymphatic Pathways

• Thoracic Duct Formation:
  • Begins at cisterna chyli from three trunks:
    • Right and Left Lumbar Trunks
    • Intestinal Trunk
  • Lumbar Trunks: Drain lower limbs, abdominal wall, pelvic organs.
  • Intestinal Trunk: Drains most abdominal organs.

Pelvic and Perineum Drainage Patterns

• Three Main Nodes:
  • External Iliac Nodes: Drain superior anterior organs (e.g., superior bladder, uterus body).
  • Internal Iliac Nodes: Drain inferior anterior organs (e.g., inferior bladder, prostate, erectile tissue, portion of vagina, superior two-thirds of anal canal).
  • Sacral Nodes: Drain posterior organs (e.g., inferior rectum, portion of vagina).
• Common Pathway: Nodes (internal, external iliac, sacral) → Common iliac nodes → Lumbar nodes → Lumbar trunks.
  • Lumbar nodes also known as para-aortic nodes.

Notable Exception

• Gonadal Lymph Drainage:
  • Testes, ovaries, uterine tube, fundus of uterus:
  • Directly to lumbar nodes, bypassing iliac nodes (embryological origin in abdomen).

Perineal Region

• Superficial Route:
  • Somatic areas (e.g., inferior third of anal canal, superficial fascia) drain to superficial inguinal nodes.
  • Indication: Palpable nodes, enlargement may indicate cancer.

Unique Pathways

• GI Tract:
  • Lymph follows blood supply to pre-aortic nodes (celiac, superior/inferior mesenteric nodes).
  • Sigmoid colon, superior rectum drain to inferior mesenteric nodes → intestinal trunk.

Interconnectivity

• Pelvic nodes exhibit interconnectivity allowing lymph and metastatic cancer to travel various directions.

Review Questions

• Bladder: First node drainage.
• Lower one-third of anal canal: Superficial inguinal nodes.
• Testes: Para-aortic/lumbar nodes.
• Scrotum: Superficial inguinal nodes.
• Body and cervix of the uterus: Internal/External iliac nodes.
• Superior rectum: Inferior mesenteric nodes.
• Lateral horns of the uterus: Superficial inguinal nodes.

Conclusion

• Comprehensive review of lymphatic drainage for pelvis and perineum.
• Emphasis on understanding patterns and exceptions.