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Right Iliac Fossa (RIF) Lump — Comprehensive Guide

Anatomy of the RIF

1. Appendix
2. Caecum
3. Terminal ileum
4. Ileocaecal lymph nodes
5. Iliac arteries (right common, external, internal)
6. Retroperitoneal connective tissue
7. Iliopsoas muscle and sheath
8. Ilium (os ilii)

1. Right kidney (unascended or hydronephrotic)
2. Gallbladder
3. Uterus / right adnexa (in females)
4. Urinary bladder (when distended)
5. Undescended right testis
6. Pelvic abscess pointing upward

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Classification of RIF Lumps

A. Parietal Swellings

• Iliac abscess (pyogenic) burrowing through the anterior abdominal wall
• Appendicular abscess pointing anteriorly
• (Inguinal/femoral herniae are discussed separately)

B. Intra-abdominal Swellings

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Detailed Differentials with Examination Findings

1. Appendicular Lump (Most Common)

• History of central/periumbilical pain shifting to RIF (Murphy's sequence) — visceral pain → parietal irritation
• Nausea, vomiting, anorexia, fever
• Constipation (sometimes diarrhoea in pelvic appendicitis)

• Position: McBurney's point area (junction of medial 2/3 and lateral 1/3 of line from umbilicus to ASIS)
• Hyperaesthesia in Sherren's triangle
• Tenderness at McBurney's point
• Muscle guarding (involuntary) over RIF
• Rebound tenderness (Blumberg's sign positive)
• Rovsing's sign positive (pressure on LIF causes pain in RIF)
• The lump: irregular, firm, tender, fixed — cannot be moved
• Percussion: may be tympanic (gas in caecum) but too tender to percuss properly
• Sluggish/absent bowel sounds over RIF on auscultation
• Psoas sign, obturator sign positive in retrocaecal/pelvic types

"The lump is irregular, firm, tender, and fixed." — S Das, Manual on Clinical Surgery, 13th Ed.

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2. Appendicular Abscess

• Patient is more toxic — high swinging pyrexia, tachycardia
• Lump becomes fluctuant — central softening within the mass
• Constitutional deterioration instead of improvement
• PR/PV examination: tender boggy mass if pelvic extension

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3. Hyperplastic Ileocaecal Tuberculosis

• Recurrent attacks of abdominal pain + diarrhoea
• Blind loop syndrome: anaemia, loss of weight, steatorrhoea
• Evening rise of temperature, night sweats, ill health
• History of pulmonary TB or exposure

• Lump in RIF: firm to hard, irregular — the caecum is pulled up (elevated) because the ileocaecal region contracts
• Tenderness is variable — less acute than appendicular lump
• Signs of anaemia, weight loss
• Key distinguishing point: In ileocaecal TB the caecum is in a high-up position (on barium studies); in Crohn's the caecum remains in normal position

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4. Crohn's Disease (Regional Ileitis)

• Mass in RIF: firm, tender — the caecum stays in its normal position (unlike TB)
• Perianal disease: fissures, skin tags, fistulae
• Shifting tenderness (unlike fixed appendicular lump)
• If sinus forms after appendicectomy → strongly suspect Crohn's

"A patient when complains of pain in the right iliac fossa along with anal fissure, fistula or oedematous skin tag, the diagnosis becomes certain." — S Das

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5. Carcinoma of the Caecum

• Disease of the elderly
• Insidious onset — iron-deficiency anaemia, anorexia, weight loss
• Occult blood in stool (rarely frank rectal bleeding)
• RIF pain is dull, non-colicky initially
• May present late as a palpable mass

• Lump: hard, irregular, relatively fixed at a later stage (when local invasion occurs)
• Signs of chronic anaemia: pallor, tachycardia
• May be mobile in early stages (compared to TB where it is fixed)
• No signs of acute infection (afebrile unless obstructed/perforated)
• Terminal ileum is normal on imaging (unlike TB)

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6. Amoebic Typhlitis

• Diarrhoea is the main feature — rarely produces a distinct lump
• Common in endemic tropical regions
• Thickened, tender caecum palpable
• Sigmoidoscopy: flask-shaped ulcers in mucosa
• Must be excluded before appendicectomy in endemic areas

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7. Actinomycosis

• Rare; usually follows perforated appendicitis
• Develops weeks after apparently straightforward appendicitis
• Abscess → retroperitoneal spread → multiple indurated discharging sinuses
• Discharge: sulphur granules (pathognomonic)
• Skin overlying RIF: indurated, discoloured, woody hard
• Biopsy confirms diagnosis

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8. Iliac Lymphadenopathy

• From the umbilicus down to the toes including anal canal, urethra, vagina (ectoderm-derived structures)

• Multiple discrete, rubbery or firm nodes
• May be tender (infective) or non-tender (lymphoma, metastases)
• Hard and fixed → metastatic
• Search for primary: examine genitalia, lower limbs, anal canal

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9. Psoas/Cold Abscess (Pott's Disease)

• Reducible swelling — disappears on pressure, re-appears on coughing
• Gives impulse on coughing
• Painless (cold abscess — no acute inflammation)
• Fluctuant — cross-fluctuation with inguinal part confirms continuity
• Swelling is medial to femoral artery (unlike femoral aneurysm)
• Signs of spinal TB: kyphosis, gibbus deformity, spine tenderness
• Hip is held in flexion (psoas spasm) — hip flexion deformity
• Chest: may have evidence of pulmonary TB

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10. Iliac Artery Aneurysm

• Expansile pulsatile swelling — pulsation felt in all directions (vs. transmitted pulsation in a mass overlying aorta, which moves only up-down)
• Deep, fixed, not mobile
• Bruit on auscultation
• Increased risk of rupture — tenderness if expanding

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11. Right Ovarian / Adnexal Mass (Females)

Tubo-ovarian Mass (Chronic Salpingitis)

• Young woman
• Previous history of pelvic peritonitis (pain, fever, bladder symptoms)
• Mass lateral to midline, mobile
• Vaginal examination confirmatory — cervical excitation tenderness, adnexal mass

Ectopic (Tubal) Pregnancy

• Missed period (amenorrhoea)
• Sudden severe lower abdominal/RIF pain + collapse
• No distinct lump early; haemoperitoneum → Cullen's sign (periumbilical bruising)
• Slow leakage → palpable mass days later, one side of uterus
• Cervical excitation tenderness on PV
• β-hCG positive

Ovarian Cyst / Tumour

• Arises from pelvis → takes central position as it enlarges
• Smooth, rounded, cystic or solid
• Dullness over the front with resonance in flanks (cf. ascites: dullness in flanks)
• Attached to uterine cornua on vaginal examination

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12. Undescended Testis (Maldescended Testis)

• Male patient — absent testis on that side of scrotum
• Firm, smooth, slightly tender mass in RIF
• At risk of torsion (sudden severe pain), malignant change (seminoma)

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13. Mesenteric Cyst

• Central or paracentral location, may extend to RIF
• Very mobile — can be moved at right angles to the line of the mesentery but not along it
• Smooth, rounded, fluctuant
• Dull on percussion, but surrounded by band of resonance (gas-containing bowel)
• May cause intermittent intestinal obstruction

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14. Mesenteric Lymphadenitis (Acute Non-specific)

• Mainly children < 6 years; rare > 14 years
• Competes clinically with appendicitis
• Pain starts periumblicically, diffuse — does not shift (unlike appendicitis)
• Klein's sign (Shifting tenderness): Tenderness in supine position — roll patient to left → tenderness shifts to left (pathognomonic); in appendicitis tenderness is relatively fixed
• Enlarged lymph nodes may be felt on deep palpation
• Temperature is only slightly raised; pulse barely elevated (unlike appendicitis where both are raised)

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15. Intussusception

• Infants/children (ileo-colic most common)
• Colicky pain → vomiting → red currant jelly stool (blood + mucus)
• Emptiness in RIF (Dance's sign) — the intussusceptum has vacated the caecum
• Sausage-shaped lump palpable in epigastrium or left lumbar region (not RIF)

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16. Retroperitoneal Tumours

• Retroperitoneal sarcoma/lymphoma: fixed, smooth, large
• Pushes bowel anteriorly (resonant anteriorly on percussion)
• Needs pyelography to exclude hydronephrosis/renal involvement

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Examination Protocol for RIF Lump

History First

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General Examination

• Temperature (fever pattern)
• Pulse (tachycardia → infection/inflammation)
• Pallor (carcinoma, TB)
• Lymphadenopathy (lymphoma, TB, metastases)
• Perianal/perineal examination (fissures → Crohn's)
• Chest examination (pulmonary TB)
• Spine: kyphosis/gibbus (Pott's disease)
• Scrotal examination in males (maldescended testis)

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Abdominal Examination

Inspection

• Visible swelling in RIF
• Visible peristalsis (obstruction)
• Discharging sinuses (actinomycosis)
• Skin changes: discolouration, induration

Palpation (Systematic)

• Hyperaesthesia in Sherren's triangle
• Voluntary vs involuntary muscle guarding — ask patient to breathe through open mouth; involuntary guarding persists; voluntary relaxes on expiration

• Define the lump:
  • Site: McBurney's point vs more medial/deep vs iliac fossa proper
  • Size and shape: Irregular (appendicular lump, carcinoma) vs smooth (cyst, abscess)
  • Surface: Irregular vs smooth
  • Consistency: Firm/hard (carcinoma, TB) vs soft/fluctuant (abscess) vs rubbery (lymph nodes)
  • Tenderness: Acute (appendicular) vs non-tender (TB, carcinoma, cold abscess)
  • Mobility: Fixed (appendicular abscess, advanced carcinoma) vs mobile (ovarian cyst, mesenteric cyst)
  • Plane: Intra-abdominal vs retroperitoneal (cannot get above it; bowel resonant in front)
  • Reducibility and cough impulse: Psoas abscess reduces and gives cough impulse
  • Pulsatility: Expansile → aneurysm; transmitted → mass over aorta

• Rovsing's sign: Pressure on LIF produces RIF pain → appendicitis
• Psoas sign: Pain on passive right hip extension (retroperitoneal inflammation)
• Obturator sign: Pain on internal rotation of flexed right hip (pelvic appendix)
• Dance's sign: Emptiness in RIF + sausage lump elsewhere → intussusception
• Klein's sign: Shifting tenderness on turning to left → mesenteric lymphadenitis
• Cross-fluctuation: Psoas abscess (iliac part ↔ inguinal part)

Percussion

• Tympanitic (gas-containing bowel overlying it) vs dull (solid mass, fluid)
• Ovarian cyst: dull centrally, resonant in flanks
• Ascites: dull in flanks, resonant centrally

Auscultation

• Sluggish or absent bowel sounds → peritonitis/ileus (appendicular lump/abscess)
• Normal bowel sounds elsewhere → localized process

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Special Examinations

• Per rectal (PR): Boggy tender mass anteriorly → pelvic abscess or pelvic appendix; hard nodule → rectal carcinoma/metastases
• Per vaginal (PV) in females: Adnexal mass, cervical excitation tenderness, uterine size, fornix fullness

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Summary Table: Key Differentiating Features

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• S Das: A Manual on Clinical Surgery, 13th Edition
• Bailey and Love's Short Practice of Surgery, 28th Edition