Groin dissections

Indications

• Superficial
  • Melanoma
  • Anal SCC
  • Merkel cell SCC
  • Vulval or vaginal SCC
• Deep - palpable nodal metastasis and/or multiple positive nodes in the superficial compartment; positive sentinel node; imaging study showing a positive node localised in the pelvis
  • Cloquet's node was previously emphasised as most important indication for deep dissection, however this is no longer universally believed

Pitfalls

• Skin flaps too thin or thick
• Injuring the ileo-femoral vessels
• Injuring the femoral nerve and its branches
• Injuring the obturator nerve
• Injuring ureter, bladder, intra-abdominal contents
• Inadequate dissection

Preparation

• Thigh mildly abducted and knee flexed
• Antibiotics
• Shave
• Tape scrotum to opposite side

Boundaries:

• Superficial - medial to medial edge of adductor longus, lateral to lateral edge of sartorius, superiorly to 3-5cm above inguinal ligament, superficial to Scarpa's fascia, deep to deep fascia/vessels

Superficial technique (aiming 5-7 nodes)

• Lazy S incision - starting 2cm medial to ASIS, then down to inguinal ligament, medial to femoral vein, then down to apex of femoral triangle
  • Alternatively - two separate incisions parallel to inguinal ligament, one 4cm below and one 4cm above
• Create skin flap just deep to Scarpa's fascia encompassing the entire dissection area - should be nice areolar plane
• Peel out specimen
  • Start laterally along sartorius, cutting down onto the overlying fascia, working from lateral to medial
  • Dissect off all the soft tissue from the front of the vessels, leaving the fascia over the vessels intact in case of wound breakdown
  • GSV often needs to be sacrificed, with suture-ligation of SFJ and then GSV again at the inferior-most part of resection, so some of it is included in the specimen (can also try to preserve it though)
  • Dissect tissue out of femoral canal and mark the highest node (Cloquet's node) with a suture
  • The superior extent is 5cm cephalad to inguinal ligament, between pubic tubercle and ASIS
• This wound can be drained, one medial and one lateral
  • TG says bring the drain out through sartorius to help a fistulous tract develop into the muscle in case there is a lymph leak, where there is better lymphatics to deal with it - seems risky for bleeding though
• Close Scarpa's fascia with 2/0 Vicryl

Deep technique

• Divide EO aponeurosis 3cm cephalad to inguinal ligament, along the direction of the fibres
• Cut down through IO and transversalis muscles/fascia
• Ligate and divide IE artery and vein at their junction with external iliac artery
• Dissect the pre-peritoneal space in the iliac fossa, exposing the entire length of external iliac vessels (identify ureter)
• Start dissection lateral to the external iliac artery. Preserve lateral femoral cutaneous nerve seen lateral to external iliac artery.
• Remove all tissue covering entire length of EI artery and vein, from the inguinal ligament to the bifurcation of internal and external iliac vessels.
• Starting at the bifurcation, dissect the tissue medial to the external iliac vein, preserving the obturator nerve. Remove tissue along the obturator neurovascular bundle to the obturator foramen surface of obturator internus.
• No drain is necessary in the pelvis
• Close transversalis fascia, muscle, IO with running 2/0 Vicryl
• Close EO

Sartorius flap

• Recommended routinely by some authors due to high incidence of wound complications
• Mobilise origin from lateral to medial, about halfway
• Transpose over femoral vessels, and suture to inguinal ligament

Post-op

• Compression can prevent wound complications
• Keep drains until output <10-30mL/day
• Keep leg elevated
• Home day 2 or 3

Complications

• Wound infection and dehiscence
• Seroma/lymphocoele
• Femoral nerve injury
• DVT
• Lymphoedema
• Femoral artery exposure and blowout