LAR / APR - Patient Positioning, Perioperative Care & Hazard Prevention

1. Overview of Procedures

2. Patient Positioning

A. LAR - Low Anterior Resection

• Patient is placed supine with both legs elevated and abducted in stirrups (Allen or candy-cane stirrups)
• Hips flexed approximately 15-20°, knees slightly flexed
• Provides simultaneous access to both the abdomen and perineum - essential for transanal stapling or circular stapler manipulation
• Arms may be tucked at the sides or on arm boards
• A steep Trendelenburg tilt (head-down, 25-30°) is used during minimally invasive (laparoscopic/robotic) cases to displace the small bowel out of the pelvis

• Foley catheter placed prior to positioning (urinary decompression + intraoperative monitoring)
• Rectal washout/irrigation with dilute iodine solution performed before the abdominal phase
• Prepped from mid-chest to proximal thighs (including perineum)
• Nasogastric tube placed
• Ureteral stents if complex pelvic anatomy anticipated

"On the operative table, the patient should be placed in lithotomy with the legs in stirrups to provide the surgeon with simultaneous access to the abdomen and perineum." - Mulholland & Greenfield's Surgery, 7th Ed.

B. APR - Abdominoperineal Resection

Phase 1 - Abdominal Phase

• Modified lithotomy (Lloyd-Davies) - same as LAR, or
• Supine with subsequent repositioning

Phase 2 - Perineal Phase

• In prone jackknife: the abdomen is closed and stoma matured first, then patient repositioned prone
• In lithotomy: stoma created after completing the perineal dissection
• Buttocks are taped apart to expose the perineal area
• Purse-string suture placed around the anus before incision to prevent fecal contamination

"The prone position offers superior exposure and visualization, especially for anterior tumors." - StatPearls (NBK574568)

3. Preoperative Care

Patient Preparation

• Mechanical bowel preparation with oral antibiotics (given day prior to surgery)
• IV antibiotics administered before skin incision (prophylaxis against SSI)
• DVT/VTE prophylaxis: both chemical (LMWH) and mechanical (compression stockings/pneumatic compression devices) approaches
• Stoma marking by an enterostomal therapy (ET) nurse - critical for APR patients who will have a permanent colostomy; for LAR patients who may need a temporary diverting ileostomy
• Ureteral stent placement by urology if complex pelvic anatomy anticipated (prior surgery, radiation, large tumor)
• Anesthesia consultation: epidural catheter or abdominal wall blocks (TAP block) planned for postoperative analgesia
• Arterial line + large-bore IV access placed
• Core temperature monitoring (esophageal/bladder probe)
• Fertility counseling for patients of childbearing age, especially with neoadjuvant radiation (ovarian transposition option for women)
• Psychological support - especially APR patients facing permanent stoma and altered body image

4. Intraoperative Hazards and Prevention

Hazard 1: Peroneal (Common Fibular) Nerve Injury

• Cause: Compression of the lateral head of the fibula against stirrups during lithotomy position
• Risk: Foot drop, sensory loss over dorsum of foot
• Prevention:
  • Ensure the fibular head is well-padded and not compressed against the stirrup
  • Use Allen stirrups (boot-style) rather than candy-cane stirrups when possible
  • Avoid extreme hip flexion/external rotation
  • Periodically check limb position during long cases

Hazard 2: Lower Limb Compartment Syndrome

• Cause: Prolonged lithotomy position + steep Trendelenburg → increased compartment pressure in the calf + reduced perfusion pressure
• Risk factors: Obesity, peripheral vascular disease, prolonged operative time (>4-5 hours)
• Clinical signs: Post-op pain, tense calf, loss of pulses, paresthesia
• Prevention:
  • Monitor peripheral pulses intraoperatively
  • Periodic positional changes/leg lowering during long procedures
  • Limit steep Trendelenburg time where possible
  • Sequential compression devices on calves

"Patients requiring prolonged Trendelenburg position during surgery are at risk of compartment syndrome, in particular obese patients and those with peripheral vascular disease. These patients require monitoring of the peripheral pulses, and position changes, to prevent compartment ischemia." - Mulholland & Greenfield's Surgery, 7th Ed.

Hazard 3: Pressure Injuries / Pressure Sores

• Cause: Prolonged pressure on bony prominences (sacrum, heels, occiput, elbows)
• Prevention:
  • Gel padding under sacrum, heels, elbows, and occiput
  • Egg-crate or viscoelastic foam mattress overlay
  • Ensure no hard surfaces contact bony prominences
  • Document skin condition pre- and post-operatively

Hazard 4: Autonomic Nerve Injury (Sexual/Urinary Dysfunction)

• Cause: Injury to hypogastric nerves, pelvic splanchnic nerves (S2-S4), or the nerve of Walsh during TME dissection
• Risk: Urinary incontinence, erectile dysfunction, retrograde ejaculation, female sexual dysfunction
• Prevention:
  • Sharp dissection along the avascular TME plane (not blunt tearing)
  • Identify and protect the superior hypogastric plexus at the sacral promontory
  • Avoid entering the presacral plane (risk of tearing sacral plexus veins causing massive haemorrhage)

Hazard 5: Presacral Haemorrhage

• Cause: Inadvertent entry into the presacral venous plexus during TME dissection
• Prevention: Careful identification of the correct areolar plane between the mesorectal fascia (MRF) and presacral fascia

Hazard 6: Deep Vein Thrombosis / Pulmonary Embolism

• Cause: Prolonged surgery, pelvic dissection, venous stasis from lithotomy
• Prevention: Sequential compression devices, LMWH prophylaxis pre- and post-op, early ambulation

Hazard 7: Hypothermia

• Cause: Lengthy procedure, open abdomen, IV fluids
• Prevention: Forced-air warming blanket, warm IV fluids, core temperature monitoring, minimise exposure

Hazard 8: Fecal Contamination

• Cause: Tumour disruption during perineal dissection (APR)
• Prevention: Purse-string suture placed around the anus before skin incision; mechanical bowel prep

5. Postoperative Care

Immediate Post-op

• Neurological and vascular assessment of lower limbs (check for nerve injury, compartment syndrome signs)
• Skin inspection for pressure injuries
• Urinary catheter monitoring (urethral injury? urinary retention from pelvic nerve injury?)
• Stoma assessment: colour (should be pink/red), viability, output (begin within 24-72 hours)
• Pain management: epidural/PCA, transition to oral analgesia
• VTE prophylaxis continued postoperatively

LAR-Specific

• Low Anterior Resection Syndrome (LARS): high stool frequency, urgency, soiling, inability to defer defecation - counsel patients preoperatively
• Anastomotic leak monitoring: fever, tachycardia, peritonism, failure to improve on day 3-5 - CT scan if suspected
• Defunctioning loop ileostomy management if created (stoma care, reversal planning at ~8-12 weeks)

APR-Specific

• Permanent colostomy care: stoma nurse education, appliance fitting, peristomal skin care
• Perineal wound care: often closed primarily; drainage maintained; risk of delayed healing (especially post-radiation)
• Phantom rectal sensation - reassure patient this is normal and temporary
• Psychological support: body image changes, sexual function discussion, support groups

6. Summary Table: Position-Related Hazards

• Mulholland & Greenfield's Surgery: Scientific Principles and Practice, 7th Ed., "Transabdominal Resection for Rectal Cancer" - directly covers lithotomy positioning, peroneal nerve hazard, and compartment syndrome risk
• Fischer's Mastery of Surgery, 8th Ed. - preoperative planning for complex pelvic and rectal resections
• StatPearls: Abdominoperineal Resection (NBK574568) - APR equipment, positioning options (prone jackknife vs lithotomy), perioperative care