Principles of Management of Urethral Injury

Overview and Anatomical Classification

• Posterior urethra: membranous + prostatic urethra (proximal to urogenital diaphragm). Almost always injured by pelvic fracture - hence called Pelvic Fracture Urethral Injury (PFUI).
• Anterior urethra: bulbar + penile (distal) urethra. Typically from straddle injuries or penetrating trauma.

Diagnosis - First Steps

1. Blood at the urethral meatus - the single most important sign
2. Inability to urinate / urinary retention
3. High-riding prostate on rectal exam (unreliable - often absent with partial tears)
4. Butterfly perineal hematoma - seen in anterior urethral (straddle) injuries
5. Pelvic fracture on X-ray / CT

• Place a 16-Fr catheter 1 cm into the fossa navicularis, fill balloon with 3 mL water
• Inject 20-30 mL water-soluble contrast in oblique/lateral decubitus position
• Partial disruption: some contrast reaches the bladder
• Complete disruption: no contrast reaches the bladder; free extravasation into pelvis ("pie-in-the-sky" bladder displaced cephalad by hematoma)

"Blood at the urethral meatus is the single most important sign of urethral injury. The importance of this finding cannot be overemphasized, because an attempt to pass a urethral catheter may result in infection of the periprostatic and perivesical hematoma and conversion of an incomplete laceration to a complete one." - Smith and Tanagho's General Urology, 19th Ed

Management Algorithm

Management of Posterior Urethral Injury (PFUI)

A. Acute / Emergency Phase

• SPT is the preferred initial treatment for most PFUI (AUA guidelines)
• Place carefully - pelvic hematoma may displace the bladder; use ultrasound guidance or open placement if needed
• Advantages: quick, avoids urethral manipulation, allows time for patient stabilization, preserves future reconstructive options
• Can be placed even in patients undergoing ORIF of pelvic fracture (no evidence it increases hardware infection risk)

• Primary surgical repair (open) is NOT recommended - very high complication rates (incontinence, ED, 69% still develop strictures requiring further surgery)
• Exception: concurrent rectal injury or bladder neck injury requires primary repair to prevent fistula

B. Primary Endoscopic Urethral Realignment (for stable patients)

• Performed within the first week after injury
• Dual antegrade + retrograde cystoscopy with fluoroscopy to bridge the urethral defect
• Urethral catheter maintained for 4-6 weeks
• Pericatheter RUG or voiding cystourethrogram at catheter removal to assess outcome
• Prolonged attempts should be avoided - do not delay other life-saving care

C. Special Situations

• Female PFUI: Early primary repair within 7 days, especially if concurrent vaginal laceration
• Children: Higher risk of injury extending to bladder neck (rudimentary prostate); manage with extra caution
• Bladder neck injury or rectal injury: Primary operative repair required

D. Delayed Reconstruction - Posterior Urethroplasty

• Timing: After 3 months (allows pelvic hematoma resolution, prostate returns to anatomic position)
• Pre-operative: RUG + VCUG to delineate stricture length (typically 1-2 cm at prostatomembranous junction)
• Procedure of choice: Excision of stricture + end-to-end anastomotic urethroplasty (bulbar urethra to prostatic apex)
• Performed via perineal approach; pubectomy sometimes needed for access
• Success rate >90% in specialist centres
• Posterior urethroplasty is a complex operation - should be performed by reconstructive specialists

Management of Anterior Urethral Injury

Straddle (Blunt) Injuries - Bulbar Urethra

1. Immediate repair: For simple, uncomplicated injuries - minimal debridement, spatulated tension-free end-to-end anastomosis over catheter using fine absorbable suture. Success >95% for short (1.5-2 cm) strictures.
2. Catheter alignment + delayed repair: Acceptable in selected cases.
3. SPT + delayed reconstruction: Preferred for:
   • High-velocity gunshot wounds / shotgun blasts
   • Extensive tissue devitalisation (true extent of injury declares itself over time)
   • Complex injuries with significant contamination

"Anastomotic urethroplasty is the procedure of choice in the totally obliterated bulbar urethra after a straddle injury... [with] success in more than 95% of cases." - Campbell Walsh Wein Urology

• Endoscopic incision/dilation for complete obliterations (doomed to failure)
• Repeated urethral dilations or DVIU for traumatic strictures (worsens fibrosis, makes subsequent reconstruction harder)
• UroLume stents - contraindicated in traumatic urethral strictures

Penetrating Anterior Urethral Injuries

• Hemodynamically stable + uncomplicated: Explore and repair primarily during index admission
• Technique: minimal debridement, spatulate the ends, primary repair over catheter with fine absorbable suture
• Extensive devitalisation / complicated injuries: SPT for urinary diversion + delayed reconstruction (typically >6 weeks)

Penile (Anterior) Urethra Injuries

• Often associated with penile fractures (tunical rupture)
• Urethral involvement in 11-29% of penetrating penile injuries
• Manage with urgent surgical exploration and primary repair

Complications to Prevent and Monitor

Key Principles - Summary

1. Never attempt urethral catheterization blindly when blood at meatus is present - do RUG first
2. RUG is the diagnostic gold standard - defines partial vs complete disruption
3. Immediate goal: secure bladder drainage (SPT is preferred for PFUI)
4. Primary open repair of PFUI is contraindicated (except bladder neck/rectal injury)
5. Partial disruption: single gentle catheter attempt acceptable
6. Complete disruption: SPT (first choice) or primary endoscopic realignment in stable patients
7. Delayed urethroplasty at 3 months is the definitive treatment for posterior disruption - success >90%
8. Anterior straddle injuries: immediate anastomotic repair for uncomplicated injuries; SPT + delayed repair for complex/devitalised tissue
9. Penetrating anterior injuries: immediate exploration + primary repair in stable patients
10. Endoscopic dilation/DVIU has no role in complete traumatic obliterations

Torsion of the Testis

Types of Torsion

1. Intravaginal Torsion (Bell-Clapper Deformity) - Most Common

• Predominantly seen in adolescents and young adults (peak at puberty)
• Incidence: ~1 in 4,000 males under 25 years
• Can occur at any age; has a bimodal distribution - first year of life and puberty

2. Extravaginal Torsion - Neonates

• 70% prenatal (in utero), 30% postnatal
• Salvage rate for prenatal torsion: nearly zero
• Salvage rate for postnatal torsion: up to 44%

Pathophysiology

Predisposing Factors

• Bell-clapper deformity (bilateral, congenital)
• Undescended testis (cryptorchid) - more prone to torsion
• Trauma (minor blunt injury)
• Cold weather / cremasteric reflex contraction
• Rapid growth during puberty
• History of previous intermittent torsion

Clinical Features

Symptoms

• Sudden onset of severe unilateral scrotal/testicular pain - the hallmark
• Pain may radiate to the groin, lower abdomen, or flank
• Nausea and vomiting (common, due to visceral pain)
• History of similar intermittent episodes (intermittent torsion) - suggests bell-clapper deformity
• No urinary symptoms (differentiates from epididymitis)
• May wake from sleep with pain

Signs

• High-riding testis with transverse (horizontal) lie - due to shortening of the cord
• Absent cremasteric reflex - most reliable clinical sign
• Diffuse testicular tenderness
• Scrotal oedema and erythema (appear later, not early)
• Prehn's sign negative: elevation of testis does NOT relieve pain (contrast: elevation relieves pain in epididymitis - "Prehn's sign positive")
• A hard, firm testis may indicate late torsion with infarction

Differential Diagnosis - Acute Scrotum

Investigations

Doppler Ultrasound

• Investigation of choice - sensitivity 96-100%, specificity 84-95%
• Shows absent or reduced blood flow in the torsed testis on colour Doppler
• Grayscale: testis may be diffusely hypoechoic and enlarged
• "Whirlpool sign": twisting of the spermatic cord above the testis - pathognomonic
• Heterogeneous echotexture = late torsion, likely non-viable testis
• Important: a negative ultrasound does NOT rule out torsion if clinical suspicion is high - do not delay surgical consultation for imaging

Other investigations

• Urinalysis: usually normal (pyuria suggests epididymitis, but may also occur with concurrent UTI in torsion)
• No specific blood tests are diagnostic

The diagnosis of testicular torsion is primarily clinical. If torsion is strongly suspected, do NOT wait for imaging - go directly to the operating room.

Management

TIME IS TESTIS - Salvage Rates by Duration

Step 1: Manual Detorsion (Temporizing)

• May be attempted in the ED while preparing for surgery
• Testis usually rotates medially (toward midline); detorsion is performed by rotating it laterally ("opening a book" - outward rotation)
• Successful manual detorsion is evidenced by pain relief and return of Doppler flow
• Does NOT replace surgery - orchidopexy is still required after successful manual detorsion
• If pain worsens with one direction of rotation, try the opposite direction

Step 2: Emergency Surgical Exploration

1. Deliver the testis and identify the twist
2. Untwist the cord (detorsion)
3. Assess viability - wrap in warm moist swabs for 5-10 minutes
   • Pink testis with restored circulation → viable → orchidopexy
   • Black/gangrenous testis with no return of colour → orchiectomy
4. Only gangrenous testes should be excised - some severely compromised but non-gangrenous testes recover and those that subsequently atrophy are not harmful

Step 3: Orchidopexy - Fixation of Both Testes

• If the torted testis is viable: bilateral orchidopexy (fixation of both testes)
• If the torted testis is non-viable (orchiectomy): contralateral orchidopexy is still mandatory
• Method of fixation: 3-point fixation of each testis to the dartos pouch using non-absorbable sutures (e.g. prolene), or fashioning a dartos pouch for each testis
• Absorbable sutures should NOT be used as they may dissolve before permanent fibrous fixation occurs
• Patient must be counselled and consented for orchidectomy before exploration

Neonatal Torsion (Extravaginal)

• Prenatal torsion: Non-urgent; testis nearly always non-viable; contralateral orchidopexy performed urgently to prevent asynchronous contralateral torsion
• Postnatal torsion: Treat as emergency - similar to adult torsion - low but real salvage rate (up to 44%)
• 93% of pediatric urologists would immediately explore a neonate with postnatal torsion

Torsion of the Appendix Testis (Hydatid of Morgagni)

• Appendix testis = remnant of Müllerian duct; appendix epididymis = Wolffian remnant
• Both are small pedunculated structures at the upper pole - can twist and infarct
• Age: 7-14 years (most common cause of acute scrotum in this age group)
• Blue-dot sign: dark infarcted appendage visible through scrotal skin at upper pole
• Doppler US: normal testicular flow; may show increased perifocal flow
• Treatment: analgesia and rest (self-limiting); surgical exploration reserved for severe pain or equivocal diagnosis
• Does NOT require orchidopexy

Complications of Testicular Torsion

Key Points Summary

1. Testicular torsion is a surgical emergency - do not delay for investigations
2. Bell-clapper deformity is the underlying anatomical defect in adolescent/adult torsion, and it is bilateral
3. The classic triad: sudden onset pain + high-riding testis + absent cremasteric reflex
4. Prehn's sign is negative in torsion (elevation does not relieve pain)
5. Doppler US is the investigation of choice but must not delay surgery in clinically obvious cases
6. Surgery within 6 hours gives >90% salvage rate
7. After detorsion, assess viability before deciding on orchidopexy vs. orchiectomy
8. Both testes must always be fixed - the contralateral testis is at equal anatomical risk
9. Non-absorbable sutures must be used for orchidopexy
10. Torsion of the appendix testis (blue-dot sign) is managed conservatively; testicular torsion always requires surgery

Anatomical Limits of Ilio-Inguinal Block Dissection

Overview

• Penile carcinoma (primary indication)
• Vulvar carcinoma
• Lower limb melanoma with palpable or proven groin metastases
• Scrotal / anal carcinoma

Part 1: Inguinal (Superficial) Component - Limits of the Femoral Triangle

Boundaries of the Femoral Triangle (Inguinal) Dissection

"The femoral triangle defined by the inguinal ligament superiorly, the adductor longus muscle medially, and the sartorius muscle laterally. The femoral nerve, artery, and vein course medial to lateral within the femoral triangle." - Hinman's Atlas of Urologic Surgery

Key Anatomical Diagram

Structures Encountered / Preserved

• Femoral nerve (deep to iliacus fascia) - preserved; motor to quadriceps, sartorius, pectineus; sensory to anterior thigh
• Femoral artery and vein - skeletonised; femoral canal nodes (including Cloquet's node) removed
• Saphenous vein - ligated at saphenofemoral junction in standard dissection (preserved in modified/limited dissection)
• Saphenofemoral junction - the fossa ovalis (saphenous hiatus) is an important landmark
• Lateral femoral cutaneous nerve - at risk along sartorius; injury causes meralgia paraesthetica
• Lymphatic channels - all ligated/clipped to prevent lymphocele

Part 2: Iliac (Deep/Pelvic) Component - Limits of the Pelvic Dissection

Boundaries of the Pelvic (Iliac) Dissection

Nodal Groups Removed in the Pelvic Component

1. External iliac nodes - along the external iliac artery and vein
2. Internal iliac (hypogastric) nodes - along the internal iliac vessels
3. Obturator nodes - in the obturator fossa, between the external iliac vein and the obturator nerve

"The boundaries of PLND include the bifurcation of the common iliac vessels proximally, the ilioinguinal nerve laterally, and the obturator nerve medially. During PLND, all nodal tissue is removed from the obturator, internal iliac, and external iliac regions." - Hinman's Atlas of Urologic Surgery

Summary: Complete Ilioinguinal Dissection Limits at a Glance

SUPERIOR:     Bifurcation of common iliac artery
              ↕ (pelvic component along external/internal iliac vessels)
SUPERIOR:     Inguinal ligament / aponeurosis of external oblique
              ↕ (inguinal / femoral triangle component)
INFERIOR:     Apex of femoral triangle (junction of sartorius + adductor longus)
LATERAL:      Sartorius muscle (inguinal) / ilioinguinal nerve (pelvic)
MEDIAL:       Adductor longus muscle (inguinal) / obturator nerve (pelvic)
ROOF:         Skin flaps raised (Scarpa fascia level)
FLOOR:        Fascia lata → femoral sheath → pelvic sidewall

Modified Ilio-Inguinal Dissection (Catalona, 1988)

• Superomedial quadrant of the inguinal region only (where the majority of positive nodes are found)
• Dissection does not extend lateral to the femoral artery or caudal to the fossa ovalis
• Saphenous vein is preserved (reduces lymphoedema)
• No sartorius transposition required
• Yields equivalent oncological control with significantly lower morbidity

Important Structures Preserved

Sartorius Transposition

Causes of Fever on Post-Operative Day 2 Following Rectal Carcinoma Surgery

1. Wind - Pulmonary (Most Common)

• Caused by: shallow breathing from pain/opiate analgesia, residual anaesthetic, prolonged recumbency, and abdominal splinting
• Collapse of small airways reduces mucociliary clearance and promotes micro-aspiration
• Features: low-grade fever, reduced breath sounds at lung bases, mild hypoxia
• Treatment: early mobilisation, incentive spirometry, physiotherapy, adequate analgesia

2. Water - Urinary Tract Infection (UTI)

• Almost all patients after rectal cancer surgery have a urinary catheter in situ - an ascending infection risk from day 1 onwards
• Particularly relevant here as pelvic dissection (APR or anterior resection) may involve close proximity to the bladder, and post-operative urinary retention is common
• Features: dysuria, cloudy urine, pyrexia; confirmed on urine culture

3. Wound / Abdominal Infection

• Anastomotic leak / peritoneal soiling: Early sub-clinical anastomosis disruption with bacterial contamination of the peritoneal cavity can present with fever from day 2. This is a particular concern after anterior resection of the rectum.
• Pelvic haematoma: Blood in the pelvis acts as a culture medium; an infected pelvic haematoma may cause fever early
• Perineal wound (after abdominoperineal resection): The large perineal wound is in direct proximity to the anal canal and perineal flora, making early infection possible

4. Walking - Deep Vein Thrombosis (DVT)

• Rectal cancer surgery is a major operation with a long pelvic dissection, carrying a high thromboembolic risk (cancer, pelvic surgery, immobility = Virchow's triad)
• DVT may produce a low-grade fever from day 2 onwards due to the inflammatory reaction around the thrombus
• Pulmonary embolism (PE) can also present with fever and is a potentially fatal cause
• DVT prophylaxis (LMWH + compression stockings + early mobilisation) is mandatory

5. Wonder Drugs - Drug Fever / Transfusion Reaction

• Drug fever: antibiotics (particularly beta-lactams), anaesthetic agents, or other medications can trigger a hypersensitivity-mediated pyrexia within 24-48 hours
• Blood transfusion reaction: common in major colorectal cancer surgery where blood loss is significant; a febrile non-haemolytic transfusion reaction typically occurs within hours of transfusion but may present up to 48 hours later
• Malignant hyperthermia: rare but important - triggered by volatile anaesthetic agents (halothane, sevoflurane) + succinylcholine; presents intraoperatively or in recovery (not day 2)

Additional Causes Specific to Rectal Cancer Surgery

Summary Table: Timing of Post-Operative Fever Causes

"Immediate postoperative fever occurring within the first 48 hours after surgery is most likely due to proinflammatory mediators causing SIRS. A fever that develops 72 hours or more after surgery is more likely to be due to infection." - Sabiston Textbook of Surgery

Measures While Operating on a Patient with Haemophilia A

Brief Background

• Mild: Factor VIII >5% (5-40 IU/dL)
• Moderate: 1-5%
• Severe: <1%

I. Pre-Operative Measures

1. Multidisciplinary Planning

• Elective surgery should only proceed after thorough coordination between the surgeon, haematologist, and anaesthetist
• Ensure availability of all laboratory and therapeutic resources before, during, and after surgery
• Avoid elective surgery if possible until haemostasis is optimised

2. Inhibitor Screening

• Up to 25% of patients with severe Haemophilia A develop inhibitory alloantibodies against Factor VIII after repeated exposure
• Pre-operative inhibitor screen should be performed at least one week before surgery
• If inhibitors are present, standard Factor VIII replacement will be ineffective - alternative agents are required (see below)

3. Assessment of Severity and Treatment Planning

• Measure baseline Factor VIII level
• Target Factor VIII level for major surgery: 80-100% of normal (>1 IU/mL)
• For minor surgery: 50-80% may suffice

4. Factor VIII Replacement (Core Measure)

Units required = Body weight (kg) × Desired rise in Factor VIII (%) × 0.5

5. Avoid Drugs that Impair Haemostasis

• Strictly avoid aspirin and NSAIDs (inhibit platelet aggregation, worsen bleeding)
• Avoid intramuscular injections
• Regional anaesthesia (e.g. epidural, spinal) should be used with extreme caution and only after adequate Factor VIII cover

II. Intra-Operative Measures

6. Anaesthesia

• General anaesthesia is preferred in most cases
• Regional blocks are relatively contraindicated due to risk of haematoma formation in deep tissues
• Endotracheal intubation should be atraumatic (risk of pharyngeal/laryngeal haematoma)

7. Surgical Technique

• Meticulous haemostasis at every step - careful ligation of every bleeding point
• Use of diathermy (electrocautery) liberally to control small vessel bleeding
• Avoid unnecessary dissection; work in dry surgical field
• Use of haemostatic agents: topical thrombin, oxidised cellulose (Surgicel), or fibrin glue at the operative site
• Minimise dead space to prevent haematoma formation

8. Intra-operative Factor VIII Monitoring

• Serial Factor VIII level monitoring intra-operatively during prolonged procedures
• Maintain Factor VIII levels >80% throughout the operation
• Multiple IV access lines should be available - keep sampling line separate from infusion line for accurate monitoring

9. Blood Products Availability

• Cross-matched blood, fresh frozen plasma (FFP), and cryoprecipitate should be immediately available in the operating theatre
• Cryoprecipitate is rich in Factor VIII (80-100 units/bag), vWF, fibrinogen, and Factor XIII - useful as adjunct when Factor VIII concentrate is unavailable

III. Post-Operative Measures

10. Continued Factor VIII Replacement

• Factor VIII levels must be maintained post-operatively:
  • First 3 days: maintain >80%
  • Days 4-7: maintain >50%
  • Days 7-14: maintain >30-50%
• Factor VIII infused every 8-12 hours (half-life) or as a continuous infusion

11. Post-operative Analgesia

• Avoid NSAIDs and aspirin for pain relief
• Use paracetamol or opioids as appropriate
• Tranexamic acid (antifibrinolytic) may be given perioperatively to stabilise clot formation, especially for oral/dental or mucosal surgery

12. Monitoring and Early Detection of Bleeding

• Regular clinical assessment for signs of haematoma or internal bleeding
• Drain output monitoring
• Repeated coagulation tests and Factor VIII levels
• Prompt re-exploration if unexpected bleeding occurs

Summary Framework (Mnemonic: PRE - INTRA - POST)

"Preoperative treatment for hemophilia A depends on disease severity. Severe phenotypes should be treated with administration of factor concentrates in the immediate preoperative setting, within 10 to 20 minutes of incision. Reducing the need for repeat dosing of factor concentrates minimizes the likelihood of inhibitor development." - Sabiston Textbook of Surgery

Anaesthetic Issues During Laparoscopic Surgery

Overview

1. CO₂ pneumoperitoneum (elevated intra-abdominal pressure + CO₂ absorption)
2. Patient positioning (Trendelenburg, reverse Trendelenburg)
3. General anaesthesia in the context of these derangements

"Proper anaesthesia management during laparoscopic surgery requires a thorough knowledge of the pathophysiology of the CO₂ pneumoperitoneum." - Schwartz's Principles of Surgery, 11th Ed

I. Cardiovascular Effects

Mechanical Effects

• Compression of the inferior vena cava (IVC) → decreased venous return → reduced cardiac filling and preload
• Compression of the aorta → increased systemic vascular resistance (SVR)
• In hypovolaemic patients, IVC compression can cause severe reduction in venous return and cardiac output

Neurohumoral Effects

• Peritoneal stretch activates the sympathetic nervous system → catecholamine release + activation of renin-angiotensin-aldosterone system + vasopressin release
• Results in: ↑ MAP, ↑ SVR, ↑ left ventricular afterload → increased myocardial work
• Net effect: ↑ heart rate, ↑ blood pressure, ↑ SVR - this combination can provoke myocardial ischaemia in patients with pre-existing coronary artery disease

Position-Related Cardiovascular Effects

Arrhythmias

• Vagal stimulation from peritoneal stretch can cause bradycardia, especially during rapid initial insufflation
• Hypercapnia (from CO₂ absorption) sensitises the myocardium → risk of ventricular arrhythmias
• Carbon dioxide gas embolism (rare but catastrophic) - causes sudden severe hypotension, raised CVP, "mill-wheel" murmur, and cardiac arrest

II. Respiratory / Pulmonary Effects

Mechanical

• Cephalad displacement of the diaphragm by elevated IAP → reduced functional residual capacity (FRC), atelectasis, increased airway resistance
• Decreased lung compliance → higher ventilatory pressures required
• V/Q mismatch → increased alveolar-arterial oxygen gradient → potential hypoxia
• Risk of endobronchial intubation - diaphragm pushed up may shift the carina, advancing an ETT into a main bronchus

CO₂ Absorption

• CO₂ is absorbed rapidly from the peritoneal cavity into the bloodstream
• Causes hypercapnia (↑ PaCO₂) and respiratory acidosis
• Must be managed by increasing minute ventilation (↑ respiratory rate or tidal volume)
• In patients with severe COPD or limited respiratory reserve, CO₂ may not be adequately cleared → may require conversion to open surgery or use of helium as an insufflant

Subcutaneous / Extra-peritoneal CO₂

• Insufflation into extraperitoneal tissue planes causes surgical emphysema → CO₂ tracks into the mediastinum, neck, and face
• Causes marked hypercapnia that cannot be corrected by increased ventilation alone

III. Anaesthetic Technique

Choice of Anaesthesia

• General endotracheal anaesthesia (GETA) with controlled mechanical ventilation is mandatory for all laparoscopic procedures
• Reasons: pneumoperitoneum restricts diaphragmatic movement; extreme positioning; prolonged procedures; cardiopulmonary derangements make spontaneous ventilation unsafe
• Regional anaesthesia is only occasionally suitable for very brief, minimal procedures

Airway Management

• Endotracheal intubation with controlled ventilation is essential
• Muscle relaxation is mandatory - prevents straining, allows adequate IAP, reduces risk of diaphragmatic injury
• Ventilator settings adjusted to increase minute ventilation to compensate for CO₂ absorption and maintain normocapnia (ETCO₂ 35-40 mmHg)

Anaesthetic Agents

• Short-acting agents preferred (desflurane, sevoflurane) - most laparoscopic procedures are day-case operations
• Propofol TIVA is an excellent choice - antiemetic properties help prevent post-operative nausea and vomiting (PONV), a major problem after laparoscopy
• Nitrous oxide (N₂O): controversial - may cause bowel distension (diffuses into gut lumen); increases PONV risk; accumulates in the peritoneal cavity and may support combustion; best avoided

IV. Monitoring Requirements

V. Positioning-Related Issues

• Trendelenburg: used for pelvic/lower GI surgery - increases intracranial pressure (ICP), intraocular pressure (IOP); risk of brachial plexus injury from shoulder braces; facial/airway oedema in prolonged cases
• Reverse Trendelenburg: used for upper GI/cholecystectomy - reduces venous return; risk of VAE
• Rare but serious: cases of postoperative blindness (ischaemic optic neuropathy) reported after prolonged steep Trendelenburg, especially with preexisting glaucoma, diabetes, or atherosclerosis

VI. Renal Effects

• Pneumoperitoneum reduces renal perfusion by compressing renal vasculature and raising venous pressure
• Oliguria is common during laparoscopy - anaesthetist should not automatically over-replace fluids assuming large insensible losses (as in open surgery)
• Insensible fluid losses during laparoscopy are negligible - IV fluid administration should be conservative and targeted to maintaining circulating volume

VII. Post-Operative Nausea and Vomiting (PONV)

• One of the most common complications after laparoscopic surgery and a major cause of unexpected admission after day-case laparoscopy
• Caused by: peritoneal gas insufflation, opioids, patient positioning, N₂O use
• Prevention: ondansetron + dexamethasone (dual antiemetic prophylaxis), propofol TIVA, avoiding N₂O, minimising opioids
• Nonnarcotic analgesics (e.g. ketorolac/NSAIDs when haemostasis is secured) should be used to reduce opioid requirements

VIII. DVT / Thromboembolism

• Elevated IAP compresses iliac veins and impedes venous return from the lower limbs → venous stasis
• Trendelenburg position further exaggerates this
• Sequential compression devices applied before induction; pharmacological DVT prophylaxis (LMWH) peri-operatively

Summary of Key Anaesthetic Issues

Prophylaxis for Deep Vein Thrombosis (DVT)

Rationale

Step 1: Risk Stratification - Caprini Score

Prophylactic Measures

A. Non-Pharmacological (Mechanical) Methods

1. Early Ambulation

• The single most important and simplest measure
• Begin within hours of surgery once patient is stable
• Activates the calf muscle pump, the primary mechanism of venous return in the legs
• Suitable for all risk levels; insufficient alone for moderate-high risk

2. Graduated Compression Stockings (GCS / TED Stockings)

• Provide 15-40 mmHg graduated pressure from ankle to thigh
• Reduce venous pooling and stasis in lower limb superficial and deep veins
• Applied pre-operatively, worn throughout hospital stay
• Contraindicated in: peripheral arterial disease (ABPI <0.8), severe leg oedema, active skin infection
• Effective as adjunct in low-risk patients; inadequate alone for high-risk

3. Intermittent Pneumatic Compression (IPC) / Sequential Compression Devices (SCD)

• Pneumatic cuffs applied to calves (and sometimes thighs), inflating sequentially from ankle upward
• Simulate the calf muscle pump; also stimulate release of endogenous fibrinolytic factors (tissue plasminogen activator)
• Applied before induction of anaesthesia and continued intra-operatively and post-operatively
• Highly effective; particularly valuable when pharmacological prophylaxis is contraindicated (active bleeding, neurosurgery, recent surgery)
• The preferred mechanical method in high-risk cases where anticoagulation is risky

4. Foot Pumps / Venous Foot Pumps

• Compress the plantar venous plexus, augmenting venous return
• Alternative when leg SCDs cannot be used (e.g. leg fractures)

B. Pharmacological Methods

1. Low-Dose Unfractionated Heparin (LDUH)

• 5,000 units SC every 8-12 hours
• Enhances antithrombin III activity; inhibits Factor Xa and thrombin
• Start 2 hours pre-operatively (or immediately post-operatively in bleeding-risk cases)
• Advantages: cheap, reversible with protamine, no dose adjustment for renal impairment
• Disadvantages: risk of Heparin-Induced Thrombocytopenia (HIT), requires twice/thrice daily injection, less efficacious in orthopaedic surgery

2. Low Molecular Weight Heparin (LMWH) - Preferred Agent

• e.g., enoxaparin 40 mg SC once daily (20 mg once daily if CrCl <30 mL/min)
• Selectively inhibits Factor Xa (greater Xa:IIa ratio than UFH)
• Advantages: once-daily dosing, more predictable response, lower risk of HIT, no routine monitoring required
• Start 10-12 hours before surgery or 6-12 hours after surgery
• Continue for 7-10 days (general surgery) or 28-35 days (major orthopaedic surgery, cancer surgery)
• Contraindicated in severe renal failure (accumulates); requires dose reduction for CrCl <30 mL/min

3. Fondaparinux

• Synthetic pentasaccharide; selective Factor Xa inhibitor
• 2.5 mg SC once daily, started 6-8 hours post-operatively
• Licensed for orthopaedic and general surgical prophylaxis
• Advantage: no risk of HIT (does not bind platelet factor 4)
• Disadvantage: longer half-life; no reversal agent; avoided in renal impairment

4. Direct Oral Anticoagulants (DOACs)

• Rivaroxaban (Factor Xa inhibitor), Dabigatran (direct thrombin inhibitor), Apixaban (Factor Xa inhibitor)
• Approved primarily for orthopaedic surgery (hip and knee replacement) prophylaxis
• Oral administration; predictable pharmacokinetics; no routine monitoring
• Reversal agents now available (andexanet alfa for Xa inhibitors; idarucizumab for dabigatran)

5. Aspirin

• 160 mg as sole agent is an alternative only when LMWH and fondaparinux are contraindicated
• Inhibits platelet aggregation (TXA₂ pathway)
• Inferior to LMWH; not recommended as first-line for surgical VTE prophylaxis
• Used adjunctively after hip/knee arthroplasty in selected lower-risk patients

6. Warfarin / Vitamin K Antagonists

• Mainly used for extended post-discharge prophylaxis or in orthopaedic surgery
• Target INR 2.0-3.0
• Disadvantage: narrow therapeutic window, requires INR monitoring, multiple drug interactions, slow onset

C. Inferior Vena Cava (IVC) Filter

• Indicated when: anticoagulation is absolutely contraindicated (e.g. active major haemorrhage) and DVT/PE risk is very high
• Retrievable filters preferred - removed once anticoagulation can be resumed
• Prevents PE but does not prevent DVT; may increase long-term risk of DVT

Risk-Stratified Prophylaxis (ACCP Guidelines)

Duration of Prophylaxis

Summary

"Options for DVT prophylaxis include intermittent pneumatic compression, use of graduated compression stockings, and administration of low-dose unfractionated heparin, low molecular weight heparin, fondaparinux, and vitamin K antagonists. Prophylaxis should be stratified based on the patient's level of risk." - Schwartz's Principles of Surgery, 11th Ed