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1. Necrotising Fasciitis

Definition

Synonyms / Variants

• Fournier's gangrene - when it affects the perineal/scrotal area
• Meleney's gangrene (synergistic gangrene) - when involving the abdominal wall
• These are variants of the same disease process

Microbiology

• Polymicrobial (most common, ~80%): Synergistic infection involving a combination of organisms:
  • Group A β-haemolytic Streptococcus (Streptococcus pyogenes) - often the leading pathogen
  • Staphylococcus aureus
  • Gram-negatives: Escherichia coli, Pseudomonas, Proteus, Klebsiella
  • Anaerobes: Bacteroides, Clostridium
• Monomicrobial: Group A Streptococcus alone (less common but highly virulent)

Risk Factors / Predisposing Conditions

• Diabetes mellitus - most common comorbidity
• Up to 30% of patients have NO identifiable comorbidity
• 80% have a history of prior trauma or infection
• Other predisposing factors: smoking, penetrating trauma, pressure sores, immunosuppression, intravenous drug abuse, perineal infection (perianal abscess, Bartholin's cysts), skin breaks (abrasions, bites, boils)
• 60% of cases commence in the lower extremities

Pathophysiology

1. Acute inflammatory infiltrate in deep fascia and subcutaneous tissue
2. Extensive necrosis of fascia and fat
3. Thrombosis of the microvasculature - leads to ischaemia and progression
4. Oedema stretching beyond visible skin changes
5. Fascial plane destruction making dissection impossible

Clinical Features

• Erythema, oedema, warmth - initially resembles cellulitis
• Unusual, disproportionate pain relative to the visible skin changes (key early clue)
• Skin turns dusky blue then black due to thrombosis and necrosis
• Crepitus - gas in tissues (especially with Clostridium)
• Bullae (vesicles, blisters) over the affected skin
• "Woody-hard" texture to subcutaneous tissues - inability to distinguish fascial planes
• Grey "dishwater" pus - characteristic discharge
• Lymphangitis is typically absent (distinguishes from cellulitis)
• Skip lesions that later coalesce

• High fever, tachycardia
• Rapid progression to septic shock
• Renal failure from hypovolaemia
• Cardiovascular collapse

Investigations

• Clinical diagnosis primarily - do not delay surgery awaiting investigations
• Creatinine kinase (CK) - enormous elevation (reflects muscle/tissue destruction)
• Biopsy of fascial layers - confirms diagnosis histologically
• Radiographs may demonstrate air in soft tissues (gas-forming organisms)
• CT scan - can show gas tracking along fascial planes, but should not delay surgery
• WBC, inflammatory markers (CRP, PCT) - markedly elevated
• Blood cultures

Management

Resuscitation

• ICU admission with careful haemodynamic monitoring
• Aggressive IV fluid resuscitation
• Oxygen supplementation; endotracheal intubation if airway compromise
• Correction of electrolyte and metabolic derangements

Antibiotics

• High-dose IV Penicillin G + broad-spectrum cover
• Third-generation cephalosporins + metronidazole (for anaerobes)
• Consider addition of clindamycin (suppresses toxin production)
• Adjust based on cultures

Surgery - the cornerstone of treatment

• Urgent radical surgical debridement as soon as possible
• Excise all devitalised, necrotic tissue generously - go beyond the area of induration to viable, healthy, bleeding tissue
• Wound is lightly packed with gauze and dressed (not closed primarily)
• Second-look operation planned at 24-48 hours (necrosis prone to spread)
• Multiple debridements often required
• Vacuum-assisted closure (VAC) dressings after debridement
• Early skin grafting in selected cases minimises protein and fluid losses

Adjuncts

• Hyperbaric oxygen therapy - may be helpful where available after debridement

Prognosis

• Mortality 30-50% (some series up to 70% without aggressive treatment)
• 30-day mortality ~26%, 1-year mortality ~40% (Danish cohort of >1500 patients)
• Mortality directly related to delay in surgical intervention

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2. Achilles Tendinitis (Tendinopathy)

Definition

Classification - Two Main Types

1. Non-insertional (Mid-portion) Achilles Tendinopathy

• Affects the mid-substance of the tendon, typically 2-6 cm proximal to the calcaneal insertion (the zone of relative avascularity)
• More common than insertional type
• Responds much better to conservative treatment
• Pathology: spindle-shaped thickening, degeneration of collagen fibres (tendinosis), hypoechoic areas on ultrasound, disruption of fibrillar pattern, increased vascularisation (neovascularisation)

2. Insertional Achilles Tendinopathy

• Involves the distal 2 cm of the tendon at its calcaneal insertion
• Often associated with:
  • Haglund's deformity - posterolateral (Haglund's) prominence of the calcaneus
  • Retrocalcaneal bursitis
  • Intratendinous calcifications / traction enthesophytes
• Responds less well to conservative management
• ~25% ultimately require surgery

3. Paratenonitis

• Inflammation of the paratenon (outer sheath/coating of the Achilles tendon)
• Painful adhesions between tendon and its sheath
• Common in runners
• Ultrasound shows hypoechoic halo around the tendon

Aetiology / Risk Factors

• Increased age
• Abnormal gastrocnemius/soleus flexibility
• Decreased subtalar motion
• Increased pronation (flat foot)
• Decreased plantarflexor strength
• Cavus foot (associated with insertional type)
• Excessive forefoot varus

• Sudden increase in training load or intensity
• Poor footwear
• Running on hard surfaces
• Fluoroquinolone antibiotics (associated with tendon degeneration/rupture)
• Corticosteroid injections (weaken tendon)

Clinical Features

• Pain and stiffness along the Achilles tendon, typically worse in the morning and at the start of activity, improving with warm-up
• Swelling and tenderness along the tendon
• Palpable nodule or thickening in mid-portion type
• Tenderness at calcaneal insertion in insertional type
• Painful posterior heel prominence (Haglund's deformity)
• Thompson/Simmonds test: patient prone, squeeze calf - absence of plantar flexion = Achilles tendon rupture
• Note: ability to stand on tiptoes does NOT exclude rupture (long toe flexors can compensate)
• Palpate the retro-Achilles bursa for retrocalcaneal bursitis

Investigations

• Clinical diagnosis in most cases
• Ultrasound - first-line imaging: shows spindle thickening, hypoechoic foci, neovascularisation (using Doppler)
• MRI - gold standard for detailed assessment: intratendinous changes, degeneration extent, associated bursitis
• Radiographs: may show calcifications, Haglund's prominence, enthesophytes

Treatment

Conservative (first-line for both types):

• RICE (Rest, Ice, Compression, Elevation)
• NSAIDs (anti-inflammatory analgesics)
• Eccentric exercise programme - first-line for non-insertional type (Alfredson protocol); strengthens musculo-tendinous unit during lengthening phase
• Heel lifts / orthotic insoles (reduce tension on tendon, correct pronation)
• Physical therapy / stretching
• Night splints / cast/brace if above fails
• Correct footwear

Intermediate interventions:

• Extracorporeal Shock Wave Therapy (ESWT) - noninvasive, good evidence, used when conservative fails before surgery; series of 30-minute sessions
• Platelet-Rich Plasma (PRP) injections - growth factors aid healing
• Ultrasound-guided tenotomy - breaks up degenerate tissue through small incision
• Braisement (paratenonitis) - ultrasound-guided injection of saline/lidocaine to break up adhesions
• Nitroglycerin patches - increase blood supply to insertional tendinopathy area
• Steroid injections - controversial (risk of tendon rupture, avoid intratendinous injection)

Surgical (when conservative fails, typically after 3-6 months):

• Open debridement of nodules and adhesions with or without paratenon resection
• If debridement exceeds 50% of tendon, FHL (flexor hallucis longus) tendon transfer is advised for augmentation
• Good outcomes in 36-77% of cases; complication rate 19-40% (infection, skin necrosis, wound dehiscence)
• Endoscopic/minimally invasive debridement increasingly used

• Resection of retrocalcaneal bursa
• Excision of posterior calcaneal tuberosity (calcaneo-plasty / Haglund's resection)
• Detachment of Achilles tendon, removal of degenerate tissue and calcifications, then reattachment (using anchors)
• FHL transfer if significant tendon involvement
• Percutaneous Zadek osteotomy for Haglund's deformity

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3. Sebaceous Cyst (Epidermoid Cyst)

Definition & Terminology

Epidemiology

• Most common cutaneous cyst
• Generally sporadic
• Can be found anywhere on the body (most common: face, scalp, neck, back, scrotum)
• Benign - no malignant potential in routine cases

Pathology

• Arise from blockage of the follicular orifice with inspissation of keratinous contents
• Lined by stratified squamous epithelium
• Filled with white/yellowish cheese-like keratin material
• Not filled with sebum (despite the name)

Clinical Features

• Subepidermal nodule, smooth, spherical, fluctuant
• Size ranges from 0.5 cm to 2 cm (can be larger)
• Central punctum (black dot) - characteristic finding; represents the blocked follicular opening
• Mobile, attached to the overlying skin but not to underlying structures
• Most patients are asymptomatic
• Complications:
  • Infection/abscess formation - skin becomes red, hot, tender; fluctuant abscess
  • Rupture - releases foul-smelling, cheese-like keratin material; causes intense local inflammatory reaction
  • Multiple cysts in Gardner's syndrome (associated with colonic polyposis - important screening implication)

Diagnosis

• Primarily clinical - history and physical examination
• Characteristic central punctum is diagnostic
• Biopsy and imaging typically not necessary

Treatment

Uninfected cyst - elective excision

• Local or general anaesthesia (GA if multiple cysts)
• Elliptical incision centred on the punctum, longer than the cyst (~1/3 its diameter in width)
• Dissect the ellipse away carefully, taking care not to rupture the cyst (rupture makes complete excision difficult)
• Seek the line of cleavage - if the cyst has never been infected, it shells out readily
• If rupture occurs, must remove all of the epithelial lining (or cyst will recur)
• Haemostasis; obliterate dead space with absorbable sutures; close skin
• Recurrence is common if epithelial lining is not completely removed

Infected/inflamed cyst

• Incision and drainage (I&D) first for acute infection (do NOT attempt complete excision of inflamed cyst - risk of rupture, incomplete removal, and wound complications)
• Allow infection to resolve
• Definitive excision after resolution of infection - reduces risk of recurrence

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4. Laparoscopic Appendectomy

Overview

Advantages of Laparoscopic Approach

• Shorter hospital stay
• Improved pain control
• Better cosmesis (smaller incisions)
• Fewer wound complications
• Diagnostic advantage: allows complete visualisation of the entire abdominal cavity - can identify alternative diagnoses when appendicitis is incorrectly suspected (tubo-ovarian abscess, typhlitis, cholecystitis, Meckel's diverticulitis)
• Particularly advantageous in obese patients and women of reproductive age (allows examination of pelvis)

Preoperative Preparation

• IV fluid resuscitation
• Foley catheter - decompress bladder to avoid injury during port placement
• Gastric decompression (NG tube) - especially if patient was not NPO for prolonged period preoperatively
• Preoperative IV antibiotics (if not already on scheduled antibiotics)
• Informed consent

Patient Positioning

• Supine, left arm tucked and padded
• Monitor positioned on patient's right side at the level of the anterior superior iliac spine
• Surgeon and assistant both positioned on patient's left side
• After port placement, position changed to reverse Trendelenburg with left side tilted down - improves visualisation of appendix and right lower quadrant

Port Placement (3-port technique)

1. 12-mm umbilical/periumbilical port (camera port) - primary access
2. 5-mm suprapubic port
3. 5-mm left lower quadrant port

Access Techniques for Peritoneal Entry

• Open (Hasson) technique - preferred in many centres: vertical skin incision just above umbilicus, down to fascia; grasp fascia with Kocher clamps, elevate and incise; blunt 12-mm trochar inserted; CO₂ insufflation established; 30-degree 5-mm camera inserted
• Veress needle - blind CO₂ insufflation then trocar
• Optiview / visual entry

Operative Steps

1. Establish pneumoperitoneum with carbon dioxide
2. Insert 30-degree camera for visualisation
3. Place remaining ports under direct vision
4. Inspection of underlying entry site - mandatory to exclude visceral injury
5. Position patient (reverse Trendelenburg, left tilt)
6. Sweep small bowel out of right lower quadrant - expose cecum, terminal ileum, and appendix
7. Use anatomic landmarks to identify appendix (taeniae coli on cecum lead to appendix base)
8. Grasp appendix tip; apply traction to expose mesoappendix
9. Divide mesoappendix (contains appendicular artery) using energy device, clips, or stapler
10. Apply endoloop ligatures or stapler to appendix base (at least 2 ligatures or endostapler)
11. Divide appendix between ligatures/stapler
12. Specimen placed in retrieval bag (endobag) - prevents wound contamination
13. Irrigation of right iliac fossa with warm saline if perforated/gangrenous
14. Inspect stump; ensure haemostasis
15. Extract specimen through umbilical port
16. Close fascia of 12-mm port sites (to prevent port-site hernia); skin closure

Complications

• Intraoperative: Bleeding from mesoappendix/appendicular artery; hollow viscus injury (bowel, bladder); injury to iliac vessels
• Early postoperative: Wound infection (less than open), intra-abdominal abscess (especially if perforated), ileus, urinary retention, DVT
• Late: Port-site hernia, adhesion obstruction (less common than open), fistula
• Stump appendicitis - rare, if stump left too long

Special Situations

• Normal appendix: must explore entire abdomen to find the cause of pain
• Perforated appendicitis: laparoscopic approach still preferred by most; thorough irrigation; consider drain
• Conversion to open: if poor visualisation, dense adhesions, or bleeding

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5. Thyroidectomy

Definition

Indications

1. Hyperthyroidism - failure or refusal of medical/radioactive iodine therapy; Graves' disease with large goitre, exophthalmos, or in young patients
2. Symptomatic goitre - compressive symptoms (dysphagia, dyspnoea, stridor, SVC obstruction)
3. Thyroid nodules and thyroid cancer (differentiated thyroid carcinoma, medullary carcinoma, follicular neoplasms, indeterminate FNA cytology)

Types of Thyroidectomy

• Total thyroidectomy - excision of all visible thyroid tissue; used for bilateral disease, cancer
• Near-total thyroidectomy - <1 g of remnant left at the Berry ligament (preserves a small cuff to protect the RLN)
• Thyroid lobectomy (hemithyroidectomy) - one lobe + isthmus + pyramidal lobe; for unilateral nodules/cancer, low-risk DTC
• Subtotal thyroidectomy - 3-5 g of tissue left bilaterally; historical approach for bilateral benign disease, less commonly done now
• Isthmusectomy - resection of isthmus and pyramidal lobe only (rare)

Preoperative Preparation

• Biochemical assessment of thyroid function (TFTs)
• Neck ultrasound - mandatory
• FNA biopsy of nodules as indicated
• For hyperthyroidism: achieve euthyroid state preoperatively with:
  • Antithyroid drugs (propylthiouracil, carbimazole)
  • Lugol's iodine solution (reduces vascularity and iodine uptake of the gland - 10-14 days preop)
  • Beta-blockers (e.g., propranolol - especially for thyroid storm prevention)
  • Radioactive iodine ablation (in some cases)
• Indirect laryngoscopy - assess vocal cord function preoperatively (baseline, and to detect pre-existing RLN palsy)
• CT scan if large goitre, substernal extension, or tracheal deviation

Anaesthesia

• Almost always general anaesthesia using a reinforced/armoured ETT
• Intraoperative nerve monitoring (IONM) - requires specialist silicone wired reinforced ETT with embedded electrodes contacting the vocal cords (NIM tube); allows monitoring of the RLN directly or via vagal stimulation; muscle relaxation contraindicated with IONM
• Alternatively: laryngeal mask with spontaneous breathing (allows endoscopic monitoring of vocal cord movement); higher risk of mask displacement
• Total intravenous anaesthesia (TIVA) may reduce coughing and improve recovery quality
• Local anaesthesia with deep and superficial cervical plexus blocks (uncommon, used with sedation)

Operative Technique (Conventional Open)

1. Position: supine, neck extended (roll under shoulders), head ring
2. Incision: collar incision (Kocher incision) in a skin crease 2-3 cm above the sternal notch
3. Raise subplatysmal flaps superiorly and inferiorly
4. Divide midline raphe between strap muscles (sternohyoid, sternothyroid); if needed, divide strap muscles transversely at their upper end (to preserve their nerve supply from ansa cervicalis)
5. Medially rotate the thyroid lobe using an Allis or Kelly clamp, retracting strap muscles laterally
6. Superior pole dissection: expose superior-pole vessels; ligate and divide individually close to the thyroid capsule to avoid injuring the EBSLN (external branch of the superior laryngeal nerve) - the "space of Reeves" (avascular space between medial superior pole and cricothyroid muscle) is useful
7. Identify and preserve the superior parathyroid gland behind the mid-superior pole at the level of the cricoid
8. Inferior pole dissection: ligate inferior pole vessels close to the thyroid; identify the inferior parathyroid gland (usually at the posterior-inferior pole)
9. Identify the Recurrent Laryngeal Nerve (RLN) in the tracheoesophageal groove before dividing any vessels; trace it to its laryngeal entry point
   • On the right: the RLN loops around the subclavian artery; it is more oblique
   • On the left: the RLN loops around the aortic arch; it runs more vertically
   • The RLN passes through the Berry's ligament (posterior suspensory ligament) - extreme care at this point
10. Ligate the inferior thyroid artery branches close to the thyroid capsule (not the main trunk) to preserve parathyroid blood supply
11. Divide the Berry's ligament and separate the thyroid from the trachea
12. Ensure parathyroid glands are preserved with their blood supply; if devascularised, auto-transplant into sternocleidomastoid muscle
13. Haemostasis; place a closed-suction drain (Redivac) if oozy
14. Approximate strap muscles, platysma, then skin closure

Complications

• RLN injury (unilateral: hoarseness; bilateral: respiratory obstruction requiring tracheostomy)
• EBSLN injury (loss of high-pitched voice, singing ability)
• Parathyroid devascularisation

• Neck haematoma - most feared immediate complication; can cause airway obstruction; requires immediate wound re-opening at the bedside
• Hypocalcaemia/tetany (transient or permanent hypoparathyroidism) - tingling, positive Chvostek's and Trousseau's signs; monitor serum calcium
• Seroma
• Wound infection
• Thyroid storm (rare, if hyperthyroid patient not properly prepared)
• Tracheomalacia (rare, in long-standing goitre)

• Permanent hypothyroidism (after total thyroidectomy; requires lifelong thyroxine)
• Permanent hypoparathyroidism (requiring lifelong calcium + vitamin D supplementation)
• Keloid/hypertrophic scar
• Voice changes

Adjunctive Technologies

• IONM (intraoperative nerve monitoring)
• Energy-sealing devices (Harmonic scalpel, LigaSure)
• Intraoperative PTH monitoring

Alternative Approaches

• Minimally invasive video-assisted thyroidectomy (MIVAT)
• Endoscopic/robotic thyroidectomy (remote access - transaxillary, transoral)
• Ultrasound-guided ablation techniques

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6. Anal Fissure

Definition

Epidemiology

• Affects all ages; most common in young adults
• Men and women equally affected
• Common after vaginal delivery and postoperatively

Location

• Posterior midline - >90% of fissures (at the 6 o'clock position in the lithotomy position)
• Anterior midline - ~10% (more common in women post-delivery)
• "Off-the-midline" fissures - should raise suspicion of secondary causes: Crohn's disease, TB, syphilis, HIV-related ulcer, leukemic infiltrate, squamous cell carcinoma of anus
• Any off-midline or non-healing fissure warrants examination under anaesthesia, culture, biopsy, and colonoscopy

Aetiology / Pathophysiology

• Precipitating cause: usually passage of a large, firm stool (constipation)
• May also occur with diarrhoea, IBD, post vaginal delivery
• Key pathophysiology: Hypertonia of the internal anal sphincter (IAS) - reduced anodermal blood flow to the posterior midline
• Cadaveric studies show decreased posterior midline blood supply; manometry shows elevated resting anal canal pressures
• Vicious cycle: Pain → IAS spasm → higher pressure → reduced blood flow → impaired healing → more pain
• Thickening of the IAS is characteristic

Classification

• Acute fissure: present <3 months; edges are fresh and well-defined
• Chronic fissure: present >3 months; characterised by:
  • Fibrosis and induration at the fissure edges
  • Hypertrophic anal papilla proximally (at the dentate line)
  • Sentinel skin tag (sentinel pile) distally (external to the anus)

Clinical Features

• Classic presentation: severe anal pain during and immediately after defecation ("like passing razor blades" or "cut glass")
• Pain may persist for 15 minutes to hours after defecation
• Pain typically absent in the morning before any bowel movement
• Small amount of bright red rectal bleeding - usually on toilet paper; frank bleeding is rare
• Fear of defecation leading to constipation (worsens the cycle)
• Chronic fissure: sentinel skin tag visible externally
• Examination: patient in left lateral decubitus position; gentle spreading of buttocks reveals the fissure; a sentinel tag may be seen; touching the fissure with a cotton-tipped applicator reproduces the pain - confirms diagnosis
• Marked increased sphincter tone on gentle digital examination
• Anoscopy deferred if extremely painful; can be performed under anaesthesia

Treatment

Acute Fissure (conservative)

• Increase oral fluids
• High-fibre diet and fibre supplements
• Sitz baths (warm water soaks) - relieve spasm
• Stool softeners (lactulose, docusate) if needed
• Avoid digital rectal examination unless diagnosis is in doubt
• Most acute fissures heal with these measures alone

Chronic Fissure (pharmacological sphincterotomy)

• 0.2-0.4% Glyceryl trinitrate (GTN) ointment applied to the anal area - a nitric oxide donor that relaxes the IAS; headache is a common side effect; healing in ~50-68%
• Topical calcium channel blockers - 0.3% nifedipine or 2% diltiazem cream; similar efficacy to GTN with fewer headaches; long-term results uncertain

• Botulinum toxin A injection into the IAS - causes temporary chemical sphincterotomy; expensive; optimal dose and injection site debated; long-term success uncertain; re-injection may be required

Surgical (lateral internal sphincterotomy)

• Standard surgical treatment and gold standard for chronic fissure
• Best long-term results: >90% healing rate, durable
• Technique: division of the distal internal anal sphincter (lateral portion) to reduce resting pressure
  • Closed technique: blind division via small anal incision
  • Open technique: direct vision
• Complication: risk of faecal incontinence (especially soiling/flatus incontinence) - most significant concern, particularly in women and elderly
• Lord's dilatation (anal stretch/dilatation) - now largely abandoned due to high incontinence rate

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7. Carbuncle

Definition

Comparison: Furuncle vs. Carbuncle

Microbiology

• Staphylococcus aureus - the causative organism (the infected patient is often a nasal carrier)
• MRSA is an increasing concern

Pathophysiology

• A furuncle (boil) develops in a hair follicle, sebaceous gland, or sweat gland
• Blockage of the gland duct with inspissation of contents predisposes to infection
• Infection spreads from a furuncle to develop one or more abscesses in adjacent subcutaneous tissues
• Results in a carbuncle - multiple interconnected abscesses with multiple pointing heads

Common Sites

• Dorsum of the neck (most common)
• Other sites with coarse hair: upper back, thighs, face
• Also noted on the dorsum of the hand

Predisposing Conditions

• Diabetes mellitus (most important - always investigate)
• Obesity
• Immunosuppression (HIV, corticosteroids, chemotherapy)
• Malnutrition
• Chronic kidney disease
• Nasal carriage of S. aureus
• Poor hygiene

Clinical Features

• Tender, indurated, erythematous mass with multiple discharging points
• Initially a firm red nodule, becoming fluctuant
• Thick creamy pus discharged from multiple openings
• Associated fever, malaise, and significant systemic upset (more than a simple furuncle)
• Regional lymphadenopathy

Treatment

Conservative (main approach):

• Antibiotics (oral or IV depending on severity and systemic features):
  • Flucloxacillin or dicloxacillin (anti-staphylococcal)
  • Co-amoxiclav or clindamycin (if MRSA suspected/confirmed: co-trimoxazole, doxycycline, or vancomycin IV)
• Antibiotics encourage the infection to localise
• After a few days, a core of slough separates leaving a surprisingly large hole, which heals rapidly by secondary intention
• Warm compresses to encourage pointing and drainage
• Treat underlying predisposing conditions (especially diabetes - optimise glycaemic control)

Surgical:

• Surgical drainage once the infection has localised (fluctuant)
• Wide local excision and drainage under GA for large carbuncles
• Cruciate incision or unroofing of all septal loculations
• Wound packed and heals by secondary intention
• Repeated dressings required during healing

Management of Chronic Furunculosis:

• Screen for diabetes and immune deficiency
• Nasal swab and decolonisation protocol (mupirocin nasal ointment; chlorhexidine body wash)
• There is little evidence of acquired immunity

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8. Divarication of Recti (Diastasis Recti)

Definition

• Diastasis recti abdominis
• Divarication of the recti
• Rectus distension / recti split
• Abdominal separation

Important Distinction from Hernia

• In diastasis recti, continuity of the midline fascia (linea alba) is maintained - there is no hernia sac and no true fascial defect
• In a ventral hernia, there is a fascial defect through which viscera or omentum can herniate
• Can easily be confused clinically - patients often present thinking they have a ventral hernia
• Diastasis recti does NOT carry a risk of strangulation

Normal Anatomy

• The two rectus abdominis muscles are normally joined in the midline by the linea alba - a fibrous band of decussating aponeurotic fibres
• Normal inter-rectus distance (IRD): <2.0 cm at the umbilicus (some define >2.5 cm as diastasis)

Pathophysiology

• The linea alba becomes stretched, thinned, and weakened without tearing
• This allows the two rectus muscles to move laterally apart
• Results in loss of abdominal core stability and midline integrity

Aetiology / Predisposing Factors

• Pregnancy (most common cause - increased intra-abdominal pressure + hormonal relaxin effects on connective tissue)
• Obesity (increased intra-abdominal pressure)
• Multiple pregnancies or large babies
• Previous abdominal surgery
• Connective tissue disorders (Marfan's syndrome, Ehlers-Danlos)
• Heavy lifting/straining
• Neonates: incompletely fused linea alba at birth (usually resolves spontaneously)
• Men with obesity/chronic increased abdominal pressure

Clinical Features

• Visible or palpable midline bulge - a ridge running down the abdomen from xiphoid to umbilicus; "doming" of the midline when abdominal muscles are engaged (e.g., head-lift test/crunch)
• Bulge is soft/jelly-like to palpation (unlike hernia which may be irreducible or tender)
• More prominent with straining; disappears when muscles are relaxed
• Lower back pain - due to lack of anterior core support; spine inadequately stabilised
• Urinary symptoms (stress incontinence) - pelvic floor weakness
• Feeling of abdominal instability
• Poor posture
• Some individuals are completely asymptomatic

Examination / Diagnosis

• Clinical exam: supine; patient performs a partial sit-up (head-lift/crunch); examiner palpates midline; can insert fingers into the gap (measure width in finger-breadths or cm)
• Ultrasound - most commonly used: measures IRD at 3 points (above, at, and below umbilicus); also assesses linea alba thickness
• CT scan - accurate measurement; useful preoperatively
• MRI - assessment of fascial integrity and associated hernias

Treatment

Conservative (first-line)

• Physiotherapy - core muscle rehabilitation programme; focus on transversus abdominis strengthening, pelvic floor exercises, and appropriate loading
• Avoid exercises that worsen the diastasis (e.g., traditional crunches, sit-ups, heavy lifting)
• Abdominal binders / splints / belly binders - provide external support, particularly postpartum
• Weight loss (in obese patients)
• Many cases improve or fully resolve with conservative management, especially postpartum cases and mild-moderate diastasis

Surgical (for exercise-resistant cases with functional impairment)

• Skin elevated near the pubic hair to the level of the xiphoid
• Plication of the linea alba - the widened area is plicated (folded and sutured together) using interrupted or continuous permanent sutures
• Creates a tighter, reinforced abdominal wall
• Combined with abdominoplasty (skin excision) if there is excess skin/skin laxity
• Mesh reinforcement added in severe cases or recurrences
• Preferred when there is excess skin or need for liposuction (plastic surgeon)

• No excess skin removal, but achieves fascial plication
• Preferred when coexisting hernia is present (general surgeon)
• Associated with shorter recovery; high success rate
• Robotic-assisted surgery emerging as an option

• Significantly improves quality of life
• Reduces back pain and urinary symptoms
• Both open and laparoscopic approaches have low recurrence and complication rates
• In a 3-year follow-up study of 60 post-partum patients who underwent surgical correction, no recurrences or long-term complications were reported

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These notes draw from Bailey and Love's Short Practice of Surgery (28th Ed.), Sabiston Textbook of Surgery, Fischer's Mastery of Surgery (8th Ed.), Sleisenger & Fordtran's GI and Liver Disease, Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Pye's Surgical Handicraft (22nd Ed.), and Sherris & Ryan's Medical Microbiology (8th Ed.).All 8 topics are covered above. Here is a quick summary of what each section contains:

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ANATOMY OF THE INGUINAL CANAL

Introduction

• Length: approximately 4 cm in adults (4-6 cm by some measures)
• Direction: passes obliquely forward, downward, and medially above the inguinal ligament
• Development: formed during the descent of the testis in fetal life; persists throughout life
• Present in both sexes but much wider in males

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Boundaries (Walls)

1. Anterior Wall

• Formed along its entire length by the aponeurosis of the external oblique muscle
• Reinforced laterally (over the deep inguinal ring) by the lowermost fibres of the internal oblique muscle (which arise from the lateral two-thirds of the inguinal ligament)
• This reinforcement by the internal oblique adds an important extra covering over the deep ring - a potential weak spot

2. Posterior Wall

• Formed along its entire length by the transversalis fascia
• Reinforced medially (along its medial one-third, posterior to the superficial ring) by the conjoint tendon (inguinal falx)
• The conjoint tendon is the fused insertion of the transversus abdominis and internal oblique muscles into the pubic crest and pectineal line
• This reinforcement strengthens the area posterior to the superficial ring

3. Roof (Superior Wall)

• Formed by the arching fibres of the transversus abdominis and internal oblique muscles
• These fibres arch over from their lateral origin at the inguinal ligament to converge medially as the conjoint tendon
• With muscle contraction, the roof descends toward the floor - a protective "shutter" mechanism against herniation

4. Floor (Inferior Wall)

• Formed by the medial half of the inguinal ligament (Poupart's ligament) - the rolled-under, thickened free inferior margin of the external oblique aponeurosis, which forms a gutter on which the contents rest
• Reinforced medially by the lacunar ligament (Gimbernat's ligament) - the medial expansion of the inguinal ligament to the pectineal line of the pubis

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Openings

Deep (Internal) Inguinal Ring

• The internal entrance to the inguinal canal
• Located midway between the anterior superior iliac spine (ASIS) and the pubic symphysis (some sources say midway between ASIS and pubic tubercle), just above the inguinal ligament
• Lies immediately lateral to the inferior epigastric vessels - this is the key surgical landmark
• It is NOT a true "hole" - it is an outpouching/tubular evagination of the transversalis fascia, which becomes the internal spermatic fascia covering the spermatic cord
• Located in the lateral inguinal fossa (as seen from the peritoneal surface)
• Lies approximately 2-3 cm above and slightly lateral to the femoral artery pulse in the groin

Superficial (External) Inguinal Ring

• The external exit from the inguinal canal
• Located just superior and lateral to the pubic tubercle
• A triangular opening in the aponeurosis of the external oblique, with:
  • Apex pointing superolaterally
  • Base formed by the pubic crest
  • Medial crus - attached to the pubic symphysis
  • Lateral crus - attached to the pubic tubercle
  • Intercrural fibres - connect the crura at the apex, preventing widening
  • Reflected inguinal ligament completes the medial floor of the ring
• The external oblique aponeurosis continues from this ring onto the spermatic cord as the external spermatic fascia

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Contents of the Inguinal Canal

In Males:

1. Internal spermatic fascia - from transversalis fascia at the deep inguinal ring
2. Cremasteric fascia and cremaster muscle - from internal oblique and transversus abdominis
3. External spermatic fascia - from external oblique aponeurosis at the superficial inguinal ring

In Females:

• Round ligament of the uterus (ligamentum teres uteri) - runs through the canal and ends in the labium majus
• Genital branch of the genitofemoral nerve

In Both Sexes:

• Ilioinguinal nerve - runs through part of the canal on top of the spermatic cord/round ligament, exiting through the superficial ring to supply sensation to the medial thigh, scrotum/labia majora, and mons pubis
• Genital branch of the genitofemoral nerve - provides sensory supply to the scrotum/labia majora and motor supply to the cremaster muscle

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Embryology and Developmental Relevance

• During fetal life, the testis descends from the posterior abdominal wall to the scrotum, pulling with it a sleeve of peritoneum - the processus vaginalis - which wraps around the testis to form the tunica vaginalis
• Normally the processus vaginalis obliterates after testicular descent (possibly under hormonal control)
• Failure of obliteration leads to:
  • Patent processus vaginalis (PVP) - predisposes to indirect inguinal hernia and communicating hydrocele
  • Congenital inguinal hernias in neonates and infants are always indirect (due to a PVP)

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Hesselbach's Triangle (Inguinal Triangle)

• Lateral: Inferior epigastric vessels (lateral umbilical fold)
• Medial: Lateral edge of the rectus abdominis muscle
• Inferior: Inguinal ligament (iliopubic tract)

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Peritoneal Folds on Internal Surface of Lower Abdominal Wall

1. Supravesical fossa - between median and medial umbilical folds → supravesical hernia
2. Medial inguinal fossa (Hesselbach's triangle) - between medial and lateral folds → direct inguinal hernia exits here
3. Lateral inguinal fossa - lateral to the lateral umbilical fold → deep inguinal ring is here → indirect inguinal hernia enters here

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Direct vs. Indirect Inguinal Hernia - Anatomical Basis

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ANATOMY OF THE ABDOMEN

1. Boundaries of the Abdomen

• Superior boundary: Diaphragm (domes up to T5 level during expiration)
• Inferior boundary: Pelvic inlet (brim)
• Posterior: Lumbar vertebrae, psoas, quadratus lumborum, iliacus
• Anterolateral: Muscles of the abdominal wall

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2. Surface Divisions of the Abdomen

Nine-Region Division (clinical and anatomical)

• Transpyloric plane (L1) - midway between jugular notch and pubic symphysis; passes through the pylorus, 1st lumbar disc, hilum of kidneys, tip of 9th costal cartilage
• Transtubercular (intertubercular) plane (L5) - joins the iliac tubercles; at level of L5
• Two vertical (midclavicular/lateral) planes - from midclavicular point to midinguinal point

Four-Quadrant Division (clinical use)

• Right Upper Quadrant (RUQ): liver right lobe, gallbladder, right kidney, ascending colon
• Left Upper Quadrant (LUQ): stomach, spleen, left kidney, tail of pancreas, descending colon
• Right Lower Quadrant (RLQ): appendix, cecum, right ovary, right ureter
• Left Lower Quadrant (LLQ): sigmoid colon, left ovary, left ureter

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3. Layers of the Anterior Abdominal Wall

(A) Skin

(B) Superficial Fascia

• Camper's fascia - superficial fatty layer; continuous with the fatty layer of superficial perineal fascia; contains the superficial inferior epigastric artery
• Scarpa's fascia - deep membranous layer; fuses with fascia lata of the thigh below the inguinal ligament; continues into the perineum as Colles' fascia

(C) Muscles of the Anterolateral Abdominal Wall

1. External Oblique

• Origin: Lower 8 ribs (outer surfaces)
• Insertion: Xiphoid process, linea alba, pubic tubercle, anterior half of iliac crest
• Fibres run: Downward and medially ("hands-in-pockets" direction)
• Aponeurosis: Broad, forms the anterior rectus sheath throughout; the lower free edge, rolled inward, forms the inguinal ligament (Poupart's ligament) from ASIS to pubic tubercle
• The lacunar ligament (Gimbernat's): Medial expansion of the inguinal ligament to the pectineal line; sharp medial edge can incarcerate femoral hernias
• The pectineal ligament (Cooper's ligament): Extension along the pectineal line of the pubis
• Superficial inguinal ring: Triangular gap in the aponeurosis lateral to the pubic tubercle

2. Internal Oblique

• Origin: Thoracolumbar fascia, anterior 2/3 of iliac crest, lateral 2/3 of inguinal ligament
• Insertion: Lower 3-4 ribs, xiphoid, linea alba, pubic crest
• Fibres run: Upward and medially (at right angles to external oblique - fan-shaped)
• Aponeurosis: Splits at the semilunar line into anterior and posterior laminae:
  • Above the arcuate line: anterior lamina → anterior rectus sheath; posterior lamina → posterior rectus sheath
  • Below the arcuate line: both laminae pass anteriorly → anterior rectus sheath only
• Lower fibres arch over the deep inguinal ring and fuse with transversus aponeurosis to form the conjoint tendon
• Contributes cremaster muscle fibres to the spermatic cord

3. Transversus Abdominis

• Origin: Inner surfaces of lower 6 costal cartilages, thoracolumbar fascia, anterior 2/3 of iliac crest, lateral 1/3 of inguinal ligament
• Insertion: Xiphoid, linea alba, pubic crest via the conjoint tendon
• Fibres run: Horizontally (transversely)
• Deepest of the three flat muscles
• Aponeurosis forms:
  • Posterior rectus sheath above the arcuate line (with the posterior lamina of internal oblique)
  • Below the arcuate line: passes entirely anterior to rectus → anterior rectus sheath
• Fuses with internal oblique to form conjoint tendon medially

4. Rectus Abdominis

• Origin: Pubic symphysis and pubic crest
• Insertion: Xiphoid process and costal cartilages of ribs 5-7
• Fibres run: Vertically
• Broad superiorly, narrow inferiorly
• Has 3-4 tendinous intersections (at the umbilicus, xiphoid, and between) - attached to the anterior rectus sheath (not the posterior)
• Two muscles separated in the midline by the linea alba

5. Pyramidalis (if present)

• Small triangular muscle anterior to the lower rectus
• Origin: pubic crest; insertion: linea alba
• Absent in 20% of people

(D) Rectus Sheath

• Only the external oblique aponeurosis forms the anterior sheath; no posterior sheath

• Anterior sheath: External oblique aponeurosis + anterior lamina of internal oblique
• Posterior sheath: Posterior lamina of internal oblique + transversus abdominis aponeurosis

• Anterior sheath: All three aponeuroses (external oblique + both laminae of internal oblique + transversus)
• Posterior sheath: Absent - only transversalis fascia and peritoneum
• The curved lower edge of the posterior rectus sheath = arcuate line (semilunar fold of Douglas); at approximately the level of the ASIS

• Rectus abdominis muscle
• Pyramidalis (below)
• Superior and inferior epigastric vessels (anastomose within the sheath)
• Terminal anterior rami of T7-T12 intercostal nerves

(E) Linea Alba

• A fibrous band in the midline from the xiphoid to the pubic symphysis
• Formed by the decussating (interlacing) fibres of the three flat muscle aponeuroses from both sides
• Above the umbilicus: relatively wide (1-2 cm)
• Below the umbilicus: narrow; virtually a single line
• The umbilicus is a scar in the linea alba - a potential weak spot for paraumbilical hernias

(F) Semilunar Line (Linea Semilunaris)

• The curved lateral border of the rectus sheath, from the 9th costal cartilage to the pubic tubercle
• The site of spigelian hernias (rare; through the semilunar line)

(G) Transversalis Fascia

• A thin fibrous sheet lining the inner surface of the transversus abdominis and iliac fossa
• Part of the general endoabdominal fascia
• Important component of the posterior wall of the inguinal canal
• Forms the internal spermatic fascia at the deep inguinal ring

(H) Extraperitoneal Fat

• Variable amount of fatty areolar tissue between transversalis fascia and the peritoneum

(I) Parietal Peritoneum

• The innermost layer

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4. Blood Supply of the Anterior Abdominal Wall

Arterial Supply

Venous Drainage

• Companion veins parallel the arteries
• Paraumbilical veins - connect the portal circulation (via umbilical vein remnant/round ligament) to the superficial epigastric veins; become dilated in portal hypertension → caput medusae
• Superficial veins drain upward to axillary veins and downward to femoral/saphenous veins

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5. Nerve Supply of the Anterior Abdominal Wall

• T7 = xiphoid process
• T10 = umbilicus (important for referred pain from appendix)
• L1 = inguinal region

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6. Posterior Abdominal Wall Muscles

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7. Peritoneum

Parietal vs. Visceral Peritoneum

• Parietal peritoneum: Lines the inner abdominal and pelvic wall; richly supplied by somatic nerves (sharp, well-localised pain)
• Visceral peritoneum: Covers organs; supplied by autonomic nerves (dull, poorly localised pain)
• Peritoneal cavity: A potential space between the two layers; contains only a thin film of serous fluid (50 mL)

Peritoneal Reflections and Specialised Structures

• Mesentery: Double fold of peritoneum connecting the small bowel to the posterior abdominal wall; contains vessels, nerves, lymphatics
• Greater omentum: Double fold from greater curvature of stomach hanging like an apron over the transverse colon and small bowel; contains fat; important in infection containment ("policeman of the abdomen")
• Lesser omentum (gastrohepatic and hepatoduodenal ligaments): Connects stomach/duodenum to liver; hepatoduodenal ligament contains the portal triad (portal vein, hepatic artery, bile duct)
• Epiploic foramen (of Winslow): Communication between the greater and lesser sacs

Greater vs. Lesser Sac

• Greater sac: Main peritoneal cavity
• Lesser sac (omental bursa): Behind the stomach and lesser omentum; enters through the epiploic foramen; communicates with the greater sac at the foramen of Winslow
• Clinical: pancreatitis fluid/pseudocysts often collect in the lesser sac

Peritoneal Fossae and Recesses

• Hepatorenal recess (Morison's pouch): Between the liver and right kidney; the most dependent part of the peritoneal cavity in the supine position - fluid accumulates here first
• Paracolic gutters: Along the lateral sides of the ascending and descending colon; right paracolic gutter communicates freely with the pelvis and subphrenic space
• Rectouterine pouch (Pouch of Douglas): Most dependent part of the female peritoneal cavity; between the uterus and rectum; site of free fluid/pus collection in pelvic sepsis
• Rectovesical pouch: Between bladder and rectum in males

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8. Abdominal Viscera - Brief Topography

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