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General Surgery — Disease Index

Written by Betra Youhanna, a medical student and not a doctor — check every detail against your own teaching.

ICC-2 GIT Surgery · 36 entries · Finals revision

C/P

Inves

Mng

Special — pathognomonic

A. Intestinal Obstruction

7 entries

Paralytic (Adynamic) Ileus

C/P

Abdominal distension ± absent/reduced bowel sounds
No true colicky pain — diffuse discomfort
Vomiting; failure to pass flatus/stool
Post-op most common setting; also peritonitis, electrolyte disturbance, drugs (opioids, anticholinergics)

Inves

AXR: generalised gaseous distension of both small AND large bowel (no cut-off point)
No mechanical obstruction on imaging

Mng

NG tube decompression + IV fluids + electrolyte correction
Treat underlying cause
Conservative; avoid opioids

Special

Functional obstruction — no mechanical cause; loss of peristalsis
Causes: post-op, peritonitis, electrolyte (↓K⁺, ↓Na⁺), drugs, ischaemia
Post-operative adynamic ileus typically lasts 3–7 days
Extraperitoneal causes: retroperitoneal haematoma, nerve-root compression, and retroperitoneal dissections (e.g. nephrectomy or sympathectomy) causing prolonged ileus

physiology · background · low-yield

Epidemiology/Risk

Small bowel ileus is the most common form of intestinal obstruction following surgical procedures (aetiology multifactorial — anaesthesia and narcotics)

Small Bowel Obstruction (SBO)

C/P

Intermittent colicky pain around umbilicus
Vomiting early
Central abdominal distension
Absolute constipation late
Hyperaudible tinkling bowel sounds
History of prior abdominal surgery or visible hernia
Proximal (high) SBO: profuse early (bilious) vomiting, very mild distension, late constipation; distal (low) SBO: much less vomiting (faeculent if late), characteristic central distension

Inves

AXR erect: multiple central fluid levels
AXR supine: determines level (jejunal vs ileal loops)
Pneumobilia → gallstone ileus
CT abdomen (confirms level, cause, strangulation signs)
Gastrografin follow-through: diagnostic + therapeutic for adhesional SBO
CT ischaemia/strangulation signs: pneumatosis intestinalis (gas in bowel wall), mesenteric fluid/stranding, bowel-wall thickening and oedema
SBO vs LBO on plain AXR — small bowel = valvulae conniventes (complete lines crossing the full lumen), central loops, dilated >3 cm; large bowel = haustra (incomplete, don't cross), peripheral, up to 6 cm (caecum up to 9 cm) — the 3/6/9 rule

Mng

Resuscitate first (IV fluids, electrolytes, NG tube, catheter)
Conservative adhesional SBO: Gastrografin; if contrast fails to reach caecum at 24–48 h → operate
Operative: hernia/malignancy cause, failed conservative, tachycardia + pyrexia + tenderness, strangulation/peritonitis
Surgery: adhesiolysis/band division; bowel resection + primary anastomosis (small bowel) ± stoma
Correct hypokalaemia before operative intervention (must be fixed prior to open surgery)

Special

Most common cause: adhesions (post-op); second: external hernia
LBO: NEVER due to adhesions alone
High-risk SBO groups: virgin abdomen, Roux-en-Y gastric bypass (internal hernia risk — mesenteric swirling on CT), hernia with narrow neck

Large Bowel Obstruction (LBO)

C/P

Insidious onset; intermittent hypogastric pain
Sudden onset → suspect volvulus
Vomiting late (vs SBO = early)
Peripheral (generalised) distension
Constipation/obstipation earlier than SBO
History of bowel habit change (malignancy)

Inves

AXR erect: multiple fluid levels (incompetent ICV) OR huge peripheral loop (competent ICV)
Coffee bean/bent inner tube sign → sigmoid volvulus
CT abdomen (cause, liver metastases)
Contrast enema or colonoscopy for tissue diagnosis
Barium enema: bird's beak in volvulus
Caecal dilation >10 cm with tenderness → impending perforation → decompress with colonic stent or defunctioning loop colostomy
Microcytic anaemia on blood picture → suspect underlying large-bowel malignancy

Mng

Resuscitate (IV fluids, NG tube, electrolytes)
Unstable/free perforation: IV broad-spectrum ABx + emergency laparotomy
Stable: colonic stenting (bridge to elective surgery or palliation)
Laparotomy options: proximal diversion / resection ± anastomosis ± covering stoma / Hartmann's
Colonoscopic decompression: sigmoid volvulus (flexible sigmoidoscope or flatus tube)

Special

Most common cause: colorectal malignancy
Competent ICV → closed loop → higher ischaemia/perforation risk
Adhesions NEVER cause LBO alone
Functional LBO: narcotics or neurovascular invasion impairing motility

physiology · background · low-yield

Epidemiology/Risk

Colorectal cancer: 33% present acutely with complications and 15% with obstruction or perforation; risk rises with advanced stage and age

Background

Stents vs surgery: stents give lower initial morbidity but are less effective (53%, high reobstruction) vs surgical resection (99%); stents safest as a bridge to elective surgery

Intussusception

C/P

Children <3 yrs: intermittent severe abdominal pain, drawing up of legs
Red currant jelly PR (bloody mucus per rectum)
Later: vomiting, distension (obstruction features)
Sausage-shaped mass in right hypochondrium
Signs of shock (pale, hypotensive, tachycardia); peritonism
Adults: nonspecific symptoms; suspect underlying tumour

Inves

AXR: absence of air on right side, or obstruction features
USS: target sign (intussuscepted segment)
Contrast/air enema: coiled spring appearance; diagnostic AND therapeutic
CT: target sign
Barium enema: claw sign (contrast around the leading edge of the intussusceptum, seen during reduction)

Mng

Resuscitation: IV fluids, analgesics, ABx, NG tube if vomiting
Therapeutic enema (barium/air/saline); CI if perforation, peritonitis, suspected tumour
Surgery if failed enema or peritonitis: gentle manipulation; resection if non-viable or Meckel's found

Special

Red currant jelly stool (pathognomonic in children)
Intussusceptum telescopes into intussuscipiens → venous congestion → ischaemia
Most common site: ileocolic junction
<3 yrs: mostly idiopathic (lymphoid hyperplasia in Peyer's patches)
Adults: suspect malignancy (2/3 of large-bowel intussusceptions)
Coiled spring on contrast enema
Lead-point associations: recent URTI, Meckel's diverticulum, Henoch–Schönlein purpura, blood dyscrasias (submucosal haematoma)

physiology · background · low-yield

Mechanism

Three prerequisites: an organ with a mesentery, a relatively fixed distal pivot, and a mobile lead point

Epidemiology/Risk

Peak age 3–9 months; spontaneous reduction in up to 10% of paediatric cases; recurrence 5–10%

Sigmoid Volvulus

C/P

Elderly (avg 60 yrs); more common in men; nursing homes/mental institutions
Increasing abdominal distension, discomfort, obstipation
Markedly distended, tympanitic abdomen

Inves

AXR: massively distended loop; both ends pointing to pelvis; bow near diaphragm — bent inner tube sign / coffee bean sign
Barium enema: bird's beak or ace of spades deformity (pathognomonic)
CT abdomen

Mng

Sigmoidoscopic decompression (non-strangulated): rubber tube through sigmoidoscope past torsion, taped to thigh
Stop if necrotic mucosa or cannot reduce → emergency sigmoidectomy + colostomy (Hartmann's)
Definitive: elective sigmoidectomy with colorectal anastomosis (~50% recurrence without resection)

Special

Coffee bean / bent inner tube on AXR; bird's beak / ace of spades on barium (pathognomonic)
>80% of all colonic volvulus
Most common cause of colon obstruction in Africa
Counterclockwise twist; predisposed by long freely mobile sigmoid + narrow mesocolon base
Predisposed by chronic constipation and a high-fibre/vegetable diet; also old age and neurologically impaired/psychiatric patients

Caecal Volvulus

C/P

More common in women; often younger than 40 years
Sudden abdominal pain; asymmetric distension
Palpable tympanitic mass in LUQ or mid-abdomen
Features of SBO (early vomiting); diarrhoea initially → obstipation follows
Percussion tenderness → suspect gangrenous bowel

Inves

AXR: large distended caecum displaced to LUQ; comma/kidney bean gas shadow
Barium enema: ace of spades / bird's beak deformity
CT abdomen
CT: whirlpool/swirl sign — mesenteric vessels wrapped tightly around the torsion axis (pathognomonic for volvulus)

Mng

Resuscitate; NO role for endoscopic decompression
Laparotomy + right hemicolectomy with ileotransverse colonic anastomosis
If gangrenous: colectomy + ileostomy
Caecopexy has high recurrence rates

Special

Clockwise rotation (vs anticlockwise for sigmoid)
Caecum displaced to LUQ on AXR (vs sigmoid = central)
Requires congenital incomplete peritoneal fixation of right colon
Younger women (vs older men for sigmoid volvulus)
Contributing factors: obstructing lesion of the distal (left) colon, midgut malrotation/nonrotation, previous surgery, pregnancy

Caecal Bascule

C/P

Intermittent bouts of abdominal pain
Spontaneously relieved (caecum falls back)
No complete obstruction

Inves

Mng

Surgical fixation

Special

Cephalad folding of caecum anteriorly over fixed ascending colon (NOT a twist)
Mobile caecum permits intermittent isolated caecal obstruction
Distinguishes from volvulus: fold/flip vs axial twist

B. Acute Abdomen

5 entries

Acute Abdomen — Approach

C/P

Severe acute abdominal pain requiring hospital admission
Classify pain: colicky (hollow viscus obstruction) vs peritonitic (constant, worse on movement, guarding, rebound)
History: onset, character, radiation, associated symptoms, progression
Posture discriminates: colicky/obstruction → patient doubled-up and restless, tender without rigidity; peritonitis → lies completely still with guarding/rebound
Onset clue: sudden onset → haemorrhage, torsion, or perforation; acute onset → inflammation or obstruction

Inves

FBC, U&E, LFTs, amylase (exclude pancreatitis before laparotomy), CRP
Erect CXR: free air under diaphragm = perforated hollow viscus
AXR, USS, CT abdomen
Women of childbearing age → mandatory pregnancy test: +ve → ectopic pregnancy (may present as sudden syncopal attack) or inevitable abortion; −ve → ovarian cyst torsion/haemorrhage

Mng

Admit; IV access + urinary catheter (monitor output)
Analgesia; IV fluid resuscitation
Definitive management by diagnosis
Unstable → resuscitate first: stable (alert, normotensive) proceeds straight to working diagnosis; unstable (drowsy, tachycardic, hypotensive, oliguric) is resuscitated first — responds → working diagnosis; no response → emergency surgical exploration
Absolute admission criteria (all-or-none): trauma, shock, disturbance of body fluids; refer to hospital for obstruction, peritonitis, or symptoms lasting >24 h

Special

Colicky pain = hollow viscus obstruction (bowel, biliary, ureteric)
Peritonitis = constant pain + guarding/rigidity + silent abdomen
Erect CXR mandatory: air under diaphragm confirms perforation
Extra-abdominal / medical mimics to exclude: expanding aortic aneurysm, MI, lower lobar pneumonia, DKA (acetone on breath), sickle-cell crisis, porphyria/periodic peritonitis

physiology · background · low-yield

Background

Definition: acute abdomen = symptoms <8 days; pain >8 days is probably not lethal / not a true acute abdomen
Mortality windows if uncorrected: haemorrhage ~24 h, plasma/fluid loss 2–3 days, sepsis/peritonitis ~7 days
Six usual causes of fatality: sepsis (peritonitis), rupture of hollow viscus, external contamination, acute disturbance of body fluids, haemorrhage, loss of plasma/other fluids
~1 in 10 presentations is a true surgical emergency; four triage questions — need for hospitalisation, haemodynamic stability, onset, pain analysis
Working diagnosis = a functional label to start management before exact pathology is known; symptom exclusion runs GIT → genitourinary → medical/metabolic
Urologic mimics: acute retention, urinary infection, dysuria (urine microscopy); sterile urine → exclude bladder cancer, chronic infection, bladder stone, urethral stricture
Abdomen mapped into 9 regions + 4 quadrants via transpyloric/transtubercular and median/transumbilical reference planes
Rarer medical simulators: anticoagulant OD / HSP / haemophilic pseudo-tumour (mimic shock); lead or strychnine poisoning, acute porphyria, abdominal tabes with lightening pain (mimic obstruction); uraemic ileus, adrenal failure, diabetic coma (mimic peritonitis)

Exam technique

Hard to assess: examination unreliable in paraplegic / post-op abdomen (no dependable guarding or sensory feedback); history unreliable in child, elderly, or disturbed sensorium (e.g. alcoholic)
Assess symptoms (pain, GIT, urinary, genital) + signs (general, parietal, abdominal, PR); absent GIT symptoms = a "good negative" pointing outside the gut

Generalised Peritonitis

C/P

Severe generalised abdominal pain
Board-like rigidity; guarding; rebound tenderness
Absent bowel sounds
Fever, tachycardia, haemodynamic instability
Generalising perforations: perforated peptic ulcer, perforated malignancy, and perforated Meckel's diverticulum (appendix & colonic diverticulum usually stay localised)

Inves

Erect CXR: free air under diaphragm (perforated hollow viscus)
Amylase (exclude pancreatitis before laparotomy)
FBC/CRP; CT abdomen
Amylase magnitude + free-gas algorithm: slightly raised amylase + air under diaphragm → perforated viscus; markedly raised amylase + no free gas → acute pancreatitis

Mng

Resuscitate: IV fluids, IV broad-spectrum ABx
Emergency laparotomy: treat underlying cause

Special

Free air under diaphragm on erect CXR = perforated hollow viscus → urgent laparotomy
Must check amylase before laparotomy (pancreatitis does NOT need primary laparotomy)
Causes: perforated peptic ulcer, appendix perforation, perforated diverticulitis
Four cause categories: perforated viscus, vascular accidents (strangulated hernia/volvulus, mesenteric ischaemia), extension of severe inflammation, and pancreatitis
No-gas pitfall: vascular accidents and severe inflammation give NO free gas with only slightly raised amylase — can be mistaken for pancreatitis

physiology · background · low-yield

Mechanism

Greater omentum normally walls off local perforations; generalised peritonitis results when the source organ is not omentally isolated

Background

Rare non-perforation inflammatory causes: Meckel's diverticulitis, Crohn's ileitis

Localised Peritonitis

C/P

Pain + tenderness + guarding in a specific quadrant
RUQ: cholecystitis
RIF: appendicitis
LIF: diverticulitis (sigmoid/descending colon)
Bowel sounds weak but present in localised peritonitis (vs absent in generalised)
Gynaecological (pelvic) localised peritonitis from septic conditions — classically salpingitis

Inves

FBC, CRP, LFTs
USS: RUQ (gallstones, GB wall thickening)
CT abdomen (diverticulitis, appendicitis)

Mng

RUQ: IV ABx; laparoscopic cholecystectomy
RIF: appendicectomy (laparoscopic)
LIF: IV ABx conservative first; surgery if failure/complications

Special

Location → diagnosis: RUQ = cholecystitis; RIF = appendicitis; LIF = diverticulitis

Biliary Colic / Acute Cholecystitis

C/P

Severe RUQ / epigastric pain (constant; onset post-fatty food)
Radiates to right shoulder tip / interscapular area
Nausea and vomiting
Jaundice if CBD involvement

Inves

LFTs (obstructive pattern)
USS RUQ: gallstones, GB wall thickening, pericholecystic fluid

Mng

Analgesia + anti-emetics
Laparoscopic cholecystectomy (definitive)

Special

—
Acute cholecystitis occurs in calcular and acalculous (non-calcular) forms

physiology · background · low-yield

Background

Biliary (foregut) colic felt as band-like upper-abdominal pain with fat intolerance; first-line imaging is ultrasound (sonography)

Ureteric Colic

C/P

Severe loin/flank pain radiating to groin, scrotum, or labium majus
Haematuria (frank or microscopic)
Restless patient (cannot find comfortable position — key distinction from peritonitis)
Nausea/vomiting; frequency/dysuria

Inves

Urine dipstick: haematuria
Non-contrast CT KUB: most sensitive for stones
AXR: radio-opaque calculi (urate stones = radio-lucent)
USS kidneys
Urine microscopy, plain urinary-tract X-ray, and IVP (intravenous urography) + ultrasound as the primary investigations

Mng

Analgesia (NSAIDs ± opioids)
IV fluids; high oral fluid intake
Urology referral for persistent obstruction

Special

Restless patient (peritonitis = still patient lying rigid)
Loin-to-groin radiation
Periodic peritonitis (Familial Mediterranean Fever): rare DDx

C. Groin Hernias

7 entries

Indirect Inguinal Hernia

C/P

Reducible swelling in groin; descends into scrotum (males)
Cough impulse
Predominant in males; most common hernia type overall
Congenital form: patent processus vaginalis

Inves

Clinical diagnosis (Zieman's test: index finger at deep ring — indirect impulse felt at index/deep ring)
USS if uncertain
Deep (internal) ring occlusion test: after reduction, pressure over the deep ring controls the hernia — no bulge/impulse on coughing (a direct hernia still bulges medially)

Mng

Children/young adults: herniotomy (sac ligation only, no mesh)
Adults: hernioplasty — Lichtenstein tension-free mesh repair
Laparoscopic: TEP or TAPP (covers Fruchaud's MPO)
Full repair spectrum: primary tissue repairs (Bassini, Shouldice), tension-free mesh (Lichtenstein — commonest), preperitoneal (Stoppa), and McVay/Cooper's ligament repair (the only technique that also repairs a femoral hernia); plug-and-patch (Gilbert / 'plugtenstein')
Complications of repair: chronic groin pain (ilioinguinal/genitofemoral nerve entrapment), ischaemic orchitis / testicular atrophy, recurrence, urinary retention, wound infection/haematoma, scrotal swelling, iatrogenic bladder/bowel/nerve/vascular injury

Special

Enters deep inguinal ring → lateral to inferior epigastric vessels → follows canal → scrotum
Congenital type = patent processus vaginalis
Most common hernia in both sexes
Three subtypes by extent of descent: bubonocele (confined to the inguinal canal) → funicular (reaches the top of the testis; processus closed just above the epididymis) → complete (descends to the bottom of the scrotum)

physiology · background · low-yield

Epidemiology/Risk

Commonest hernia overall — 75% of all abdominal hernias are inguinal, 75% of inguinal are indirect; ~20× commoner in men; more frequent on the right (60%); ~20% bilateral

Exam technique

Invagination test: impulse felt on the tip of the little finger (direct = pulp); on coughing the bulge travels lateral→medial down the canal (direct = deep→superficial)

Background

Sac lies within the spermatic cord (coverings = attenuated cord layers) and should be opened at operation

Other

Groin-swelling DDx (deck's 9): inguinal hernia, femoral hernia, inguinal lymphadenitis, infantile hydrocele, saphena varix, lipoma of cord, groin abscess, funiculitis, undescended testis

Direct Inguinal Hernia

C/P

Bulge directly through posterior wall of inguinal canal (Hesselbach's triangle)
Reducible; does not descend into scrotum
Older men; acquired (posterior wall weakness)
Straight protrusion on coughing; reaches full size immediately on standing and reduces immediately on lying down (vs indirect = delayed, oblique)
Acquired predisposing factors — chronically raised intra-abdominal pressure (chronic cough/COPD, constipation with straining, bladder-outflow obstruction straining at micturition, ascites, heavy lifting, pregnancy, obesity) plus collagen weakness (ageing, smoking, connective-tissue disorders e.g. Ehlers-Danlos, Marfan)

Inves

Clinical (Zieman's test: middle finger at superficial ring — direct = impulse at middle finger)
USS if uncertain
Deep ring occlusion test: the hernia still bulges / shows an impulse on coughing despite occluding the deep ring (it protrudes medial to it through Hesselbach's triangle)

Mng

Hernioplasty: Lichtenstein tension-free mesh repair
Laparoscopic: TEP or TAPP

Special

Medial to inferior epigastric vessels (vs indirect = lateral)
Through Hesselbach's triangle: lateral rectus border / inferior epigastric vessels / inguinal ligament
Always acquired; never congenital
Malgaigne's bulging — a weak, soft, supple bulge appearing on straining/leg-raising; signifies poor abdominal wall tone (older/obese) and indicates the hernia needs mesh (hernioplasty) rather than primary tissue repair

physiology · background · low-yield

Epidemiology/Risk

Commonly bilateral (~50%); almost always acquired in older men

Background

Sac lies posterior to the cord, not covered by cord layers; not routinely opened unless obstruction is present

Exam technique

Zieman's 3-finger test (index on deep ring, middle on superficial ring, ring finger over saphenous opening): a direct hernia hits the middle finger

Femoral Hernia

C/P

Small, hard, often irreducible swelling below and lateral to pubic tubercle
More common in women (wide pelvis → wider femoral canal)
Often incarcerated at presentation
DDx: inguinal hernia, lymph node (Cloquet's node), saphena varix, lipoma, femoral artery aneurysm, psoas abscess
Occult femoral hernia — suspect in an elderly woman (60–80) presenting with small-bowel obstruction and no prior abdominal surgery

Inves

Clinical; USS
Zieman's test: ring finger over the saphenous opening (femoral)

Mng

Urgent repair (high strangulation risk — narrow femoral ring)
Mesh repair; open or laparoscopic
Named approaches: Lockwood (low, below inguinal ligament), Lotheissen (trans-inguinal), McEvedy (high/vertical); femoral ring obliterated by suturing inguinal ligament to Cooper's ligament ± mesh (excise sac, inspect contents, close canal)

Special

Below inguinal ligament; lateral to pubic tubercle (vs inguinal = above ligament + medial to pubic tubercle)
Narrow femoral ring → highest strangulation risk of all hernias
Femoral canal normally contains only fat + Cloquet's lymph node
Femoral ring boundaries: anterior = inguinal (Poupart's) ligament, posterior = pectineal (Cooper's) ligament, medial = lacunar ligament, lateral = femoral vein
Beware the aberrant obturator artery (corona mortis) running along the lacunar ligament when placing the medial suture — injury causes catastrophic bleeding
The sac emerges through the femoral canal and saphenous opening, then deflects upward and laterally over the inguinal ligament — a large one can be mistaken for an inguinal hernia

physiology · background · low-yield

Epidemiology/Risk

~4× commoner in women (60–80 yrs), usually right-sided; roughly one-third (40%) present with incarceration/strangulation, sometimes Richter's type

Mechanism

Female predominance is due to the wider pelvis and a smaller bulk of pectineus

Other

DDx clues: saphena varix — soft, disappears on lying, cough impulse + venous hum, ± leg varices; psoas abscess — flexed hip, painful extension; distended psoas bursa — disappears on hip flexion (also add psoas bursa & haematoma to the DDx list)

Sliding Hernia

C/P

Part of hernial sac wall formed by adjacent viscus (caecum on right; sigmoid on left)
Usually presents as inguinal hernia
The sliding viscus forming the sac wall may also be a portion of the urinary bladder (either side) or the ovary — not only caecum (right) / sigmoid (left)

Inves

Often intraoperative finding; imaging may suggest
Suspect a sliding hernia in any large hernia that cannot be completely reduced (missing it risks inadvertent entry into bowel or bladder at operation)

Mng

Careful dissection — do NOT resect sac wall (= bowel wall)
Anatomical reduction of viscus; mesh repair
Repaired by the Bevan technique (sac reduced with inverting sutures after freeing from the cord — the viscus is never dissected off the peritoneum, which would devascularise it → fistula/peritonitis); very large ones reduced via a separate peritoneal incision and fixed to the posterior wall; higher recurrence than simple hernias

Special

Viscus forms part of hernial sac wall (not just contents)
Right side = caecum; left side = sigmoid colon
Deck: occurs exclusively in males and is most commonly left-sided

physiology · background · low-yield

Epidemiology/Risk

Accounts for ~5% of indirect inguinal hernias

Pantaloon Hernia

C/P

Combined direct + indirect inguinal hernia in same patient
Two sacs straddling the inferior epigastric vessels

Inves

Intraoperative finding

Mng

Mesh repair covering both defects

Special

Straddles inferior epigastric vessels ("trouser-leg" shape)

Richter's Hernia

C/P

Can strangulate WITHOUT complete bowel obstruction
Localised tenderness at hernial site; no classic obstruction symptoms
Common in femoral and Spigelian hernias

Inves

Clinical; high index of suspicion required

Mng

Urgent surgical repair; resection if bowel wall necrotic

Special

Only anti-mesenteric wall (partial circumference) enters sac → partial strangulation WITHOUT obstruction
Femoral + Spigelian hernias most commonly involved
Because the bowel lumen stays patent the patient still passes stool/flatus (no absolute obstruction) → delayed presentation while the trapped antimesenteric knuckle necroses and perforates

Strangulated / Obstructed Hernia

C/P

Irreducible, tense, tender hernia; absent cough impulse
Obstruction: vomiting, distension, absolute constipation
Strangulation: severe pain, fever, tachycardia, local erythema/oedema, metabolic acidosis

Inves

Clinical; WBC (leucocytosis = strangulation); metabolic acidosis
AXR: obstruction features
CT abdomen

Mng

Resuscitate THEN operate (resuscitate first, even with strangulation/perforation)
Emergency hernia repair; assess bowel viability intraoperatively
Non-viable bowel: resection ± primary anastomosis ± stoma
No synthetic mesh in contaminated (strangulated) field
Obstructed (not yet strangulated) hernia: gentle Taxis — sedation, Trendelenburg position, intermittent pressure on the neck; abort after 2–3 attempts (risk of reducing gangrenous bowel or reduction en masse), then resuscitate and operate
At emergency surgery, open the sac at its fundus first to evacuate the toxic fluid before dividing the constriction ring (prevents flushing toxic fluid into the peritoneal cavity)

Special

Mechanism: tight narrow neck → venous congestion → arterial ischaemia → infarction
Strangulation = vascular compromise (venous first → arterial)
Lactic acid may be normal (no venous outflow to circulate it)
Reduction en masse — forced Taxis pushes the sac plus its intact constricting neck back into the abdomen; the external bulge disappears (false reassurance) but the bowel remains strangulated inside

physiology · background · low-yield

Other

Garrey's stricture — an ischaemic fibrotic stricture at the old constriction ring, found on a bowel loop after a strangulated hernia has been reduced
A strangulated omentocele can occur without any intestinal obstruction
Initial resuscitation before theatre: NG suction, IV fluid/electrolyte replacement, antibiotics; high-pitched bowel sounds with rushes if obstructed

Mechanism

Tough tissues that constrict and precipitate strangulation: the external ring (funicular oblique hernia) and the lacunar ligament (femoral hernia)

D. Ventral Hernias

6 entries

Epigastric Hernia

C/P

Small (often asymptomatic) midline lump between xiphoid and umbilicus
Larger: epigastric pain/dyspepsia; may mimic peptic ulcer disease
Can strangulate: erythematous/purplish skin + tense, irreducible swelling over the summit = impending strangulation → urgent surgical exploration

Inves

Clinical (small ones missed without specific examination)
USS

Mng

Primary suture for small defects; mesh repair for larger

Special

Through linea alba above umbilicus
Often contains only extraperitoneal fat (no peritoneal sac)
Often multiple defects along the linea alba ("Swiss cheese" defects)
Exclude peptic ulcer before repair (vague symptoms can mimic PUD)

physiology · background · low-yield

Epidemiology/Risk

Typically middle-aged males (3rd–4th decade), ~4× commoner in males; common in manual workers; autopsy incidence 0.5–10%

Mechanism

Evolves: protrusion of extraperitoneal fat between linea alba fibres → drags a small peritoneal sac → eventually contains a piece of greater omentum

Umbilical Hernia

C/P

Infantile: protrudes at umbilicus during crying/straining; rarely strangulates; wide neck
Adult (true umbilical): through umbilical cicatrix; obese or cirrhotic patients
Congenital: exomphalos (covered by sac, at umbilicus) vs gastroschisis (no sac, lateral to umbilicus)

Inves

Clinical

Mng

Infantile: observe — closes spontaneously by 2–4 years; surgery if persistent or symptomatic
Adult: surgical repair (does not resolve spontaneously)
Large defects: prosthetic repair with preperitoneal mesh

Special

Infantile type: rarely strangulates (wide neck)
True umbilical: through umbilical cicatrix itself
DDx of a periumbilical mass: caput medusae, metastatic deposit (Sister Mary Joseph nodule), umbilical granuloma, omphalomesenteric duct remnant cyst, urachal cyst

physiology · background · low-yield

Epidemiology/Risk

Infantile: ~1 in 5 live births; 8× higher in black and Asian infants than Caucasian

Mechanism

Congenital (exomphalos): failure of midgut to return from the extraembryonic coelom; sac covered by amnion/Wharton's jelly with no skin and no umbilical cicatrix

Paraumbilical Hernia

C/P

Swelling adjacent to (not through) umbilicus
Common in obese multiparous women
Often large; can be irreducible; carries strangulation risk

Inves

Clinical; CT for large hernias

Mng

Surgical repair: Mayo repair (vest-over-pants overlapping technique) or mesh
Does NOT resolve spontaneously; strangulation risk justifies elective repair

Special

Adjacent to umbilical cicatrix (NOT through it) — distinguishes from true umbilical hernia
More common in obese multiparous women
Mayo repair (vest-over-pants): upper leaf overlaps lower leaf
Narrow neck relative to sac volume → prone to irreducibility, obstruction and strangulation

physiology · background · low-yield

Epidemiology/Risk

Middle-aged women >35 years, ~5× commoner in females

Background

Sac usually contains coils of small and large intestine and omentum; gradually enlarges and hangs downward

Incisional Hernia

C/P

Hernia through previous surgical scar
Often asymptomatic initially ("concealed burst" — skin healed but fascia disrupted)
Serosanguinous wound discharge = classic sign of fascial dehiscence
Progressive bulge; can be large/multilocular
Long-standing: skin ulceration over the summit (adherent to a papery scar)
Typically presents within 1 year of the operation

Inves

Clinical; CT for large/complex hernias
CT assesses the defect and contents and detects loss of domain

Mng

Tension-free synthetic mesh repair (recurrence 2–10% vs up to 50% with primary suture)
Mesh positions: onlay / inlay / retrorectus / preperitoneal / intraperitoneal
Laparoscopic repair: mesh + tacking sutures + full-thickness abdominal wall sutures
Small solitary defect (<3 cm): primary closure with non-absorbable suture; interpose omentum beneath mesh to reduce fistula formation

Special

Begins as musculofascial disruption in early post-op period
Wound infection = most important aetiological factor
Vertical incisions > transverse/oblique (higher risk)
Primary fascial repair largely abandoned (up to 50% recurrence)
Obstruction common (adhesions in sac) but strangulation rare (relatively wide neck)
DDx: phantom hernia (from muscle paralysis) — check the defect edge does not reach bone/xiphisternum

physiology · background · low-yield

Epidemiology/Risk

Incidence 10–50% after open laparotomy, 1–5% at laparoscopic port sites (4–21% of laparotomies overall)
Risk factors: age >70, morbid obesity (stronger than immunosuppression), malnutrition, cancer, diabetes, chronic cough/COPD, emergency surgery, reoperation, no prophylactic antibiotics, stoma creation

Diastasis Recti (Divarication)

C/P

Visible midline bulge between recti on coughing/straining
Common in elderly multiparous women with weak abdominal muscles
No true hernial ring or neck

Inves

Clinical; USS; CT

Mng

Preperitoneal mesh repair for large symptomatic cases
Conservative if asymptomatic
If repaired for cosmesis: excise a strip of linea alba and reapproximate the recti

Special

NOT a true hernia (no hernial ring → no strangulation risk)
Aponeuroses of rectus sheath excessively stretched → recti separate widely on straining

physiology · background · low-yield

Mechanism

Represents functional failure of both the upper respiratory and umbilical buffer zones of the abdominal wall

Spigelian Hernia

C/P

Soft, reducible mass lateral to rectus abdominis, below umbilicus
Impulse on coughing
Common in women >50 years
Can be interparietal (external oblique intact over sac — difficult to palpate)

Inves

Clinical; USS (interparietal location can be subtle); CT

Mng

Surgical repair (open or laparoscopic)

Special

At junction of linea semilunaris and linea semicircularis (90% below umbilicus)
Defect through internal oblique + transversus abdominis; external oblique intact over sac (interparietal)
Strangulation common (narrow defect)
Richter's type can occur here

physiology · background · low-yield

Epidemiology/Risk

Precipitating factors: obesity, chronic cough, old age, multiple pregnancies

Background

Sac usually lies intraperitoneal

E. Abdominal Trauma

2 entries

Blunt Abdominal Trauma

C/P

Following MVA, fall from height, direct blow, seatbelt injury
May have no external signs of injury
Haemodynamic instability despite resuscitation
Abdominal rigidity; shoulder tip pain (haemoperitoneum causing diaphragmatic irritation)
Seat belt sign: horizontal ecchymosis/bruising across the abdomen — raises suspicion of mesenteric avulsion / small-bowel injury

Inves

FAST: free fluid in peritoneum/pericardium/pleura — primary imaging tool
DPL: if FAST unavailable or equivocal + haemodynamically unstable
CT abdomen: haemodynamically stable only
CXR/AXR: rib fractures, pneumoperitoneum, diaphragm rupture, psoas shadow loss

Mng

3Rs: Resuscitate → Reassess → Re-evaluate
IV access in upper limbs ONLY (IVC injury = lower limb IV ineffective)
Never remove embedded foreign body in field (tamponade effect)
Laparotomy: haemodynamic instability despite resuscitation; positive FAST/DPL + instability; peritonism; hollow viscus/diaphragm injury
Before urethral catheter, exclude urethral injury — high-riding prostate on PR (or blood at meatus) → do NOT catheterise
Retroperitoneal haematoma zone management: Zone I (central — aorta/IVC/pancreas/duodenum) always explore; Zone II (flank/renal) open only if expanding or pulsatile; Zone III (pelvic) do not open (releasing tamponade worsens bleeding)

Special

IV access upper limbs ONLY (IVC may be injured)
Never remove impaled objects in field
FAST first; CT only if haemodynamically stable
Trimodal death distribution: immediate (minutes), early (hours), late (days–weeks)
Spleen = most commonly injured organ in blunt abdominal trauma
Lethal triad of death: acidosis + hypothermia + coagulopathy — self-perpetuating; indication for damage-control surgery

physiology · background · low-yield

Mechanism

Blunt mechanisms: compression causing crush injury; abrupt shearing force tearing organs or vascular pedicles; sudden rise in intra-abdominal pressure rupturing a viscus

Epidemiology/Risk

Causes: motor vehicle crashes (~75%), falls (vertical deceleration), motorcycle/bicycle crashes, assaults
Trimodal death: immediate ~50% (brainstem/cord/great-vessel lacerations), early ~30% (golden hour — CNS/chest/blood loss), late ~20% (MODS/sepsis)

Physiology

Time to peritoneal signs varies by organ: vascular = immediate hypovolaemia with few physical findings; solid = variable; hollow viscus (small bowel) slow, often within 24 h

Exam technique

PR & PV mandatory in assessment; blood on PR indicates bowel injury; pelvic fractures also palpable on PR

Background

Take AMPLE history (Allergies, Medications, Past history, Last oral intake, Events) plus mechanism/weapon and patient position at injury

Penetrating Abdominal Trauma

C/P

Stab wound or gunshot wound to abdomen
Evisceration (bowel protruding through wound)
Signs of peritonitis or haemodynamic instability

Inves

Clinical + FAST assessment
CT abdomen (haemodynamically stable only)
Local wound exploration: assess peritoneal breach in stab wounds
Back/flank stab wounds (stable): triple-contrast CT with selective (observation) management rather than mandatory laparotomy

Mng

Laparotomy: haemodynamic instability; evisceration; peritonitis; hollow viscus/vascular injury
Gunshot wounds: nearly always require laparotomy
Stab wounds: selective — peritoneal signs → laparotomy; stable + no signs → local wound exploration
Never remove impaled foreign body in field; IV upper limbs only

Special

Gunshot wounds = nearly always explore (high KE, unpredictable trajectory)
Stab wounds = selective management
Never remove impaled FB (maintains tamponade)
Organ pattern: stab → liver most commonly; gunshot → small bowel most commonly

physiology · background · low-yield

Mechanism

Gunshot wounds transfer higher kinetic energy with cavitation and heat effects; shotgun and impalement injuries also occur

F. Anatomy Pearls

4 entries

Inguinal Canal Anatomy

C/P

Inves

Mng

Special

~4 cm oblique channel; deep → superficial ring
Deep (internal) ring: opening in transversalis fascia; just above midpoint of inguinal ligament
Superficial (external) ring: triangular defect in external oblique aponeurosis; above pubic tubercle
Anterior wall: external oblique aponeurosis (+ internal oblique laterally)
Posterior wall: transversalis fascia (+ conjoint tendon medially)
Roof: arching fibres of internal oblique + transversus abdominis
Floor: inguinal ligament (+ lacunar ligament medially)
Male contents: spermatic cord + ilioinguinal nerve
Female contents: round ligament + ilioinguinal nerve
Also transmits the genital branch of the genitofemoral nerve (in both sexes, alongside the ilioinguinal nerve)

physiology · background · low-yield

Background

Deep and superficial rings are almost superimposed in infants (separate as the pelvis widens with growth)
Superficial ring bounded by a superomedial and inferolateral crus, joined by criss-cross intercrural fibres
Dissection direction: open repair considers anatomy skin → peritoneal cavity; laparoscopic (TAPP/TEP) considers it abdominal cavity → skin
Conjoint tendon attaches to the pubic crest and adjoining pectineal line

Exam technique

Superficial ring normally will not admit the tip of the little finger

Mechanism

The external (superficial) ring is the commonest strangulating agent in a funicular oblique hernia descending to the scrotum (acts as a rigid collar)

Hesselbach's Triangle & Fruchaud's MPO

C/P

Inves

Mng

Special

Hesselbach's triangle (direct hernias pass through here): medial = lateral rectus border; lateral = inferior epigastric vessels; inferior = inguinal ligament
Fruchaud's Myopectineal Orifice (MPO): all groin hernias emerge through this single zone; bounded by conjoint tendon (superior) / Cooper's ligament / pecten ossis pubis (inferior) / iliopsoas (lateral) / rectus abdominis (medial)
Laparoscopic mesh covers entire MPO → one mesh covers direct + indirect + femoral hernias (TEP/TAPP)
Triangle of Doom: between vas deferens (medially) + spermatic vessels (laterally); contains external iliac vessels — avoid staples
Triangle of Pain: lateral to spermatic vessels; contains femoral nerve + lateral femoral cutaneous nerve — avoid staples
Circle of Death (Corona Mortis): anastomosis between obturator vessels and external iliac/inferior epigastric vessels; risk of fatal haemorrhage
The medial umbilical ligament (obliterated umbilical artery) subdivides Hesselbach's triangle into medial and lateral halves

physiology · background · low-yield

Background

MPO is an osseo-myo-aponeurotic tunnel — egg-shaped from the anterior (open) view, quadrilateral from the posterior (laparoscopic) view; the inguinal ligament + iliopubic tract divide it into a superior compartment (exit for direct + indirect sacs) and an inferior compartment (femoral nerve, artery, vein, lymphatics)

Mechanism

Inherent MPO weakness arises embryologically from the egress of the testicle/round ligament and the iliac neurovascular bundle from the intra-abdominal compartment

Spermatic Cord Contents

C/P

Inves

Mng

Special

3 arteries: testicular artery (from aorta) / artery to vas deferens (from inferior vesical) / cremasteric artery (from inferior epigastric)
Veins: pampiniform plexus → testicular vein
3 other structures: vas deferens / sympathetic nerves + autonomic plexus / lymphatics (to para-aortic nodes)
Also: remnant of processus vaginalis / genital branch of genitofemoral nerve / cremasteric muscle fibres
3 fascial coverings (dragged from the abdominal wall during testicular descent): external spermatic fascia (from external oblique aponeurosis) / cremasteric muscle & fascia (from internal oblique) / internal spermatic fascia (from transversalis fascia)

physiology · background · low-yield

Physiology

There is no parasympathetic supply to the testicles

Background

The ilioinguinal nerve runs in the canal but lies external to the cremasteric fascia (outside the cord), whereas the genital branch of genitofemoral runs inside the cord — both at risk during repair

Anterior Abdominal Wall Layers

C/P

Inves

Mng

Special

Superficial → deep: Skin → Camper's fascia (superficial fatty layer) → Scarpa's fascia (deep membranous layer) → External oblique aponeurosis → Internal oblique → Transversus abdominis → Transversalis fascia → Preperitoneal fat → Peritoneum
Camper's fascia: superficial, fatty; continues as dartos in scrotum
Scarpa's fascia: deep, membranous; fuses below inguinal ligament; continues as Colles' fascia in perineum
Transversalis fascia: forms deep inguinal ring; lines posterior surface of transversus abdominis

Additions — Approach & OSCE

3 entries

Littre's Hernia

C/P

Any hernia (classically a groin hernia) whose sac contains a Meckel's diverticulum

Mng

Resect the diverticulum if it is symptomatic or strangulated

Special

Named for its content (Meckel's diverticulum), one of the sac-content eponyms alongside enterocele/omentocele

Maydl's Hernia (Hernia-in-W)

C/P

Two bowel loops sit in the sac with an intervening 'W' loop lying back inside the abdomen

Special

Surgical trap: the strangulated segment is the intervening intra-abdominal loop, while the loops visible in the sac may look viable — inspect the intra-abdominal loop before closing

Amyand's Hernia

C/P

Hernia sac containing the appendix (which may be inflamed — appendicitis within the sac)

Additions — Approach & OSCE

2 entries

Obturator Hernia

C/P

Protrusion through the obturator canal (rare pelvic hernia)

Special

Howship–Romberg sign — pain along the medial aspect of the thigh due to compression of the obturator nerve
Other pelvic hernias — Sciatic: peritoneal sac through the greater/lesser sciatic foramen → swelling on the buttock (may involve the sciatic nerve or obstruct the ureter). Perineal: through the pelvic floor, split by transversus perinei — anterior = labial / lateral vaginal-wall swelling; posterior = between rectum and ischial tuberosity.

Lumbar Hernia (Petit's / Grynfeltt–Lesshaft)

C/P

Petit's hernia: through the inferior lumbar triangle (Petit's triangle)
Grynfeltt–Lesshaft hernia: through the superior lumbar triangle

Classifications & Frameworks

13 entries

Hernia Severity Classification

Stages (Ascending Severity)

Stage	Definition
Reducible	Contents return to abdomen spontaneously or with pressure
Irreducible (Incarcerated)	Cannot be returned; no vascular compromise yet
Obstructed	Bowel lumen occluded; no vascular compromise
Strangulated	Vascular compromise present (venous → arterial ischaemia)
Loss of domain	Viscera have lost right of abode — cannot reduce without tension

SBO vs LBO — Comparative Features

Feature	SBO	LBO
Pain	Central/periumbilical, colicky	Hypogastric, intermittent
Vomiting	Early	Late
Distension	Central	Peripheral/generalised
Constipation	Late	Earlier
Bowel sounds	Hyperaudible tinkling	May be absent
Main cause	Adhesions / hernia	Malignancy
AXR	Central fluid levels, jejunal/ileal loops	Peripheral loop; coffee bean (volvulus)
Due to adhesions?	YES (most common)	NEVER

SBO — High-Risk Groups

Group	Key Risk	Action
Virgin abdomen	No prior surgery → malignancy risk	Close surgical scrutiny; low threshold for operation
Roux-en-Y gastric bypass	Internal hernia + adhesive SBO; mesenteric defects	CT with oral+IV contrast; consider diagnostic laparoscopy
Hernia	Narrow neck = strangulation risk	CT to assess neck width; avoid manual reduction if strangulation signs

SBO — High-Risk Findings Requiring Operation

Clinical

Fever + chills + peritoneal signs → operative intervention
Haemodynamic instability NOT responsive to IV fluids

Laboratory

Significant leucocytosis → compromised bowel (lower operative threshold)
Lactic acidosis → earlier surgery (normal lactate does NOT exclude venous outflow ischaemia)

Imaging

Closed loop (isolated dilated segment)
Non-physiologic free fluid
Bowel dilation >3 cm (perforation risk)
Pneumatosis intestinalis (anaerobic mural infection = ischaemia)
Free abdominal air (perforation)
Mesenteric oedema (venous strangulation)

Gastrografin Protocol

Contrast failure to reach caecum by 24–48 h → conservative management will fail → operate

Indications for Laparotomy — Intestinal Obstruction

Operative Indications

Underlying cause requires surgical treatment (hernia, colonic carcinoma)
Patient does not improve on conservative management
Signs of strangulation or peritonitis
Tachycardia + pyrexia + abdominal tenderness → operate regardless of cause

Key Principle

Resuscitate FIRST, even if strangulation or perforation found — then open

Management Principles — Intestinal Obstruction (7 Key Points)

7 Key Points

Level of obstruction is a pivotal decision point (SBO vs LBO)
SBO: often rapid onset; commonly due to adhesions or hernia
LBO: may be gradual/intermittent; often carcinoma or strictures; NEVER adhesions alone
All obstructed patients need fluid and electrolyte replacement
Many adhesion SBO patients will settle on conservative treatment
Seek and confirm cause before operation wherever possible
Tachycardia + pyrexia + abdominal tenderness → operate whatever the cause

Caecal vs Sigmoid Volvulus — Comparison

Feature	Caecal Volvulus	Sigmoid Volvulus
Incidence	Less common; more in females; younger age group	Commoner; equal sex frequency; fifth decade
Cause	Lack of fixation of caecum to retroperitoneum	Long/floppy mesentery; narrow mesocolon base
Predisposing	Previous surgery, pregnancy, malrotation	Obstructing left colon lesions, old age, chronic constipation, neurologically impaired, high-fibre diet
Rotation	Clockwise	Anticlockwise (commonly)
Clinically	Sudden pain; asymmetric distension; tympanitic mass in LUQ/mid-abdomen; features of SBO	Sudden pain; markedly distended + tympanitic abdomen
Plain X-ray	Dilated caecum displaced left; comma/kidney bean; concavity facing inferiorly/right	Markedly dilated sigmoid central; bent inner tube/coffee bean; inferior convergence points to left pelvis
Contrast enema	Confirm diagnosis; exclude distal carcinoma	Bird's beak / bird of prey / ace of spades
Treatment	No endoscopic role; laparotomy + right hemicolectomy	Endoscopic detorsion → elective colectomy; if fails → laparotomy + sigmoidectomy

Indications for Laparotomy — Blunt Abdominal Trauma

Indications

Haemodynamic instability despite adequate resuscitation
Positive FAST or DPL with haemodynamic instability
Signs of peritonism (guarding, rebound, absent sounds)
Evidence of hollow viscus injury (free air on CXR/CT)
Diaphragm rupture
Expanding or pulsatile retroperitoneal haematoma

Indications for Laparotomy — Penetrating Abdominal Trauma

Indications

Haemodynamic instability
Evisceration
Peritonitis
Signs of hollow viscus or major vascular injury
Gunshot wounds to abdomen (nearly always require laparotomy)

Stab Wounds (Selective)

Peritoneal signs → laparotomy
Stable with no peritoneal signs → local wound exploration first

3R Trauma Framework

Step	Action
Resuscitate	IV fluids (upper limbs only), airway, breathing, circulation
Reassess	Repeat ABCDE; response to resuscitation; identify all injuries
Re-evaluate	Decision to operate vs ongoing observation; repeat imaging if stable

Key Rules

IV access upper limbs only (IVC injury → lower limb IV ineffective)
Never remove embedded foreign body in field

Mesh Position Nomenclature (International Hernia Collaboration)

Position	Name
A	Onlay (above fascia)
B	Inlay
C	Retrorectus (retromuscular)
D	Preperitoneal
E	Intraperitoneal

Evidence

Primary fascial repair: up to 50% recurrence → largely abandoned
Tension-free mesh repair: 2–10% recurrence → standard of care

ABCs of Bowel Obstruction

Letter	Meaning
A	Adhesions — most common cause of SBO
B	Bulge (hernia)
C	Cancer — most common cause of LBO

Nyhus Classification (Groin Hernia)

Type	Defining features
Type I	Indirect inguinal hernia with normal internal inguinal ring
Type II	Indirect inguinal hernia with dilated internal ring but intact posterior wall
Type III	Posterior wall defect — IIIA direct inguinal; IIIB indirect inguinal (dilated ring encroaching transversalis fascia / sliding); IIIC femoral
Type IV	Recurrent hernia — IVA direct; IVB indirect; IVC femoral; IVD combined

Nyhus is based on integrity of the internal ring and the posterior wall: Type I/II = intact posterior wall; Type III = broken posterior wall; Type IV = recurrent.

Bowel Gas, Obstruction & Perforation Signs

Small vs large bowel (AXR)

Small bowel: valvulae conniventes cross the FULL lumen width; dilated >3 cm; central
Large bowel: haustra do NOT cross full width; peripheral

Obstruction

SBO: dilated central loops + valvulae conniventes; erect >3 air-fluid levels; AXR shows pattern but NOT the transition point (CT does)
LBO: peripheral, more dilated, haustra; commonest causes tumour/volvulus
Coffee bean sign → sigmoid/caecal volvulus
CT with IV contrast → complete/small-bowel obstruction; Gastrografin → suspected perforation

Perforation / pneumoperitoneum

Erect CXR first-line — free gas under right hemidiaphragm; CT most sensitive (supine: gas anterior to liver)
Rigler's sign (AXR) = gas outlines BOTH sides of bowel wall
CT: extra-luminal contrast leak

Modality Selection & Organ-Specific Signs

Bowel

IBD: UC lead-pipe (loss of haustra) + backwash ileitis; Crohn string sign + cobblestone + skip lesions; double-contrast barium enema CI in acute severe colitis
Appendicitis: US if young/slim, else CT — thick oedematous wall ± appendicolith + peri-appendiceal fat stranding
Diverticulitis: diverticulosis + fat stranding + wall inflammation
Ischaemic bowel enhancement (post-contrast): arterial → hypodense; venous → hyperdense; ± pneumatosis

Biliary / pancreas

Gallstone US: hyperechoic + posterior acoustic shadow; CT terminology hyper/hypodense (NOT 'radio-opaque')
MRCP (heavy T2, bile bright): thin normal CBD; stones = black filling defects → proximal dilatation
Acute pancreatitis CT: structureless pancreas + smudged peripancreatic fat

Urology / vascular / gynae

Renal colic: CT KUB non-contrast (most stones radio-opaque; gallstones radiolucent → US); stone at PUJ → hydronephrosis
Ruptured AAA: elderly man, back pain + shock; CT if stable (fast 6 h)
Ectopic: +pregnancy test + empty uterus + adnexal sac on US; ~95% ampullary; interstitial/cornual highest bleed risk