General Surgery
Final Professional MBBS — General Surgery. Explanation-first answers that teach the reasoning behind every fact, with classifications, comparison tables, drug doses, clinical pearls and key-point recaps from Bailey & Love and SRB's Manual.
THE CONCEPT
Acute appendicitis is inflammation of the vermiform appendix and is the commonest abdominal surgical emergency. Almost the entire disease can be understood from a single initiating event — obstruction of the appendiceal lumen — which sets off a predictable cascade ending in gangrene and perforation if untreated. Knowing this sequence explains the symptoms, the signs, the urgency, and the complications.
PATHOGENESIS — A LOGICAL SEQUENCE
The lumen becomes obstructed — most often by a faecolith, or by lymphoid hyperplasia (common in the young), and rarely by a tumour or worms. Behind the obstruction, mucus and bacteria accumulate, raising intraluminal pressure. This distension compresses first the veins and lymphatics, causing ischaemia; the ischaemic mucosa ulcerates, allowing bacterial invasion of the wall (suppurative appendicitis). Progressive ischaemia leads to gangrene and then perforation, which either forms a walled-off appendicular mass or abscess or spills into the peritoneum causing generalised peritonitis.
CLINICAL FEATURES — WHY THE PAIN SHIFTS
The classic history of migrating pain is explained by the two nerve supplies of the peritoneum. Initially the inflamed appendix produces poorly localised, colicky central (periumbilical) pain — because the appendix is a midgut structure whose visceral afferents refer to the T10 dermatome. As inflammation reaches the parietal peritoneum of the right iliac fossa, the pain becomes sharp, constant and localised to the right iliac fossa (McBurney's point). Accompanying features are anorexia (almost invariable), nausea, vomiting and a low-grade fever.
EXAMINATION SIGNS
- Tenderness and guarding at McBurney's point (two-thirds along from umbilicus to the anterior superior iliac spine), with rebound tenderness.
- Rovsing's sign — pressure in the left iliac fossa produces pain in the right iliac fossa.
- Psoas sign (pain on hip extension — retrocaecal appendix) and the obturator sign (pain on internal rotation of the flexed hip — pelvic appendix).
- Signs of peritonitis (rigidity, absent bowel sounds) if perforated.
INVESTIGATION
The diagnosis is chiefly clinical, supported by a neutrophil leucocytosis and raised CRP. A urine dipstick helps exclude a urinary tract infection, and a pregnancy test is mandatory in any woman of childbearing age to exclude an ectopic pregnancy. Ultrasound or CT is valuable in atypical presentations, in women, and in the elderly; scoring systems such as the Alvarado score aid decision-making.
DIFFERENTIAL DIAGNOSIS & MANAGEMENT
The differential is wide — mesenteric adenitis, ectopic pregnancy, ovarian cyst torsion, pelvic inflammatory disease, ureteric colic, Meckel's diverticulitis and Crohn's disease. Treatment is appendicectomy (laparoscopic or open through a Lanz/grid-iron incision) with intravenous fluids and antibiotics; selected uncomplicated cases may be treated with antibiotics alone.
💡CLINICAL PEARL: The two signature clues: pain that shifts from the umbilicus to the right iliac fossa (visceral then parietal peritoneal irritation), and a positive Rovsing's sign. Never forget the pregnancy test in women — a ruptured ectopic can masquerade as appendicitis and is immediately life-threatening.VARIATIONS IN POSITION & PRESENTATION
The appendix has a variable position, and this explains atypical presentations. A retrocaecal appendix (the commonest position) may give flank or right-loin pain with a positive psoas sign and relatively little anterior tenderness; a pelvic appendix lies near the bladder and rectum, causing suprapubic pain, diarrhoea or urinary symptoms and a positive obturator sign; and a post-ileal appendix may produce vomiting and diarrhoea that mislead. Awareness of these positions prevents missed diagnoses, especially where the classic McBurney's-point tenderness is absent.
SPECIAL GROUPS — WHY DIAGNOSIS IS HARDER
Appendicitis is more dangerous and harder to diagnose at the extremes of life and in pregnancy. In the very young and the elderly, presentation is often atypical and perforation more frequent because diagnosis is delayed. In pregnancy, the enlarging uterus displaces the appendix upward, shifting the pain, and the gravid patient's symptoms overlap with normal pregnancy — so a high index of suspicion and ultrasound are used to avoid the serious fetal risk of a perforated appendix.
COMPLICATIONS & THE BOTTOM LINE
Untreated appendicitis progresses to perforation, then to a walled-off appendicular mass or abscess or to generalised peritonitis, with rarer sequelae such as portal pylephlebitis and sepsis. The bottom line is that appendicitis remains a clinical diagnosis demanding prompt appendicectomy: the cost of a modest negative-appendicectomy rate is accepted because the cost of a missed, perforating appendix is far greater.
💊KEY POINTS / NUMBERS (viva)- Diagnosis is mainly clinical + leucocytosis/CRP; pregnancy test mandatory in women; imaging (US/CT) if atypical.
- Treatment = appendicectomy (laparoscopic/open) + IV fluids + antibiotics.
- Complications: perforation, appendicular mass/abscess, peritonitis.
🔑KEY POINTS TO REMEMBER- Commonest abdominal surgical emergency; caused by luminal obstruction (faecolith, lymphoid hyperplasia) → distension → ischaemia → gangrene → perforation.
- Pain shifts from periumbilical (visceral, T10) to right iliac fossa/McBurney's point (parietal); with anorexia, nausea, low fever.
- Signs: RIF tenderness/guarding/rebound, Rovsing's, psoas and obturator signs.
- Mainly clinical + leucocytosis/CRP; urine dip + pregnancy test (exclude ectopic); US/CT if atypical.
- Treat by appendicectomy + fluids + antibiotics; wide differential especially gynaecological in women.
📚SOURCES: Bailey & Love's Short Practice of Surgery; SRB's Manual of Surgery.THE CONCEPT & CLASSIFICATION
Intestinal obstruction is a blockage to the onward passage of bowel contents, and it is classified along three useful axes: by level (small vs large bowel), by mechanism (mechanical obstruction vs functional/paralytic ileus), and, most importantly for safety, by whether it is simple or strangulated — the latter meaning the blood supply is compromised, threatening bowel viability. This classification directs both diagnosis and treatment.
CAUSES
A helpful anatomical framework divides mechanical causes into those in the lumen, in the wall, or outside the wall:
Level Common causes Small bowel Adhesions (commonest), herniae, Crohn's stricture, intussusception, gallstone ileus, tumour Large bowel Colorectal carcinoma (commonest), sigmoid volvulus, diverticular stricture Functional Paralytic ileus (post-operative, peritonitis, electrolyte disturbance) THE FOUR CARDINAL FEATURES
Four symptoms define obstruction, and their relative prominence localises the level:
- Colicky abdominal pain — from vigorous peristalsis against the obstruction.
- Vomiting — early and profuse in high/small-bowel obstruction, late and feculent in large-bowel obstruction.
- Distension — greater and more central/peripheral the more distal the obstruction (marked in large-bowel obstruction).
- Absolute constipation (no faeces or flatus) — an early feature of large-bowel obstruction, a late feature of small-bowel obstruction.
RECOGNISING STRANGULATION
The critical judgement is spotting strangulation, because it demands emergency surgery. Its warning signs are a change from colicky to continuous, severe pain, localised tenderness and peritonism, fever and tachycardia, and a rising lactate — all indicating ischaemic, potentially necrotic bowel.
INVESTIGATION
An abdominal X-ray shows dilated loops and air-fluid levels: small bowel lies centrally with valvulae conniventes crossing the whole lumen, whereas large bowel lies peripherally with haustra that only partly cross; a volvulus gives a 'coffee-bean' loop. CT is the key investigation — it identifies the level, the cause, and signs of ischaemia. Bloods and lactate assess the patient's state.
MANAGEMENT
Initial management of most obstruction is conservative — the 'drip and suck' approach: nil by mouth, a nasogastric tube to decompress the stomach, intravenous fluids with correction of electrolytes, and monitoring of urine output. Adhesive small-bowel obstruction without strangulation often settles with this. Surgery is indicated for strangulation, an obstructed/irreducible hernia, a complete or malignant large-bowel obstruction, and failure of conservative treatment.
💡CLINICAL PEARL: Remember the two commonest causes by level: adhesions for small-bowel and colorectal cancer for large-bowel obstruction. The life-saving skill is recognising strangulation — continuous pain, peritonism, fever, tachycardia and a rising lactate — which converts a 'drip and suck' patient into an emergency laparotomy.FLUID SHIFTS & THE SICK PATIENT
A key point often underestimated is the massive fluid loss of obstruction. Litres of fluid are sequestered in the distended, non-absorbing bowel and lost through vomiting, producing dehydration, hypovolaemia and electrolyte disturbance (notably hypokalaemia). This 'third-space' loss is why aggressive intravenous fluid replacement and careful electrolyte correction — guided by urine output — are as important as decompression, and why the patient can be far sicker than the abdomen alone suggests.
CLOSED-LOOP OBSTRUCTION
A particularly dangerous form is closed-loop obstruction, where the bowel is blocked at two points (as in a volvulus or an obstructing colonic cancer with a competent ileocaecal valve). The trapped segment cannot decompress in either direction, so pressure rises rapidly, threatening ischaemia and perforation — classically of the caecum in large-bowel obstruction (the caecum has the largest diameter and, by Laplace's law, the highest wall tension). This is a surgical emergency even without other signs of strangulation.
PARALYTIC ILEUS — THE CONTRAST
It is important to contrast mechanical obstruction with paralytic ileus, a functional failure of peristalsis (after surgery, with peritonitis, or from electrolyte disturbance such as hypokalaemia). Here there is distension and vomiting but the pain is not colicky and, crucially, bowel sounds are absent rather than the hyperactive 'tinkling' sounds of mechanical obstruction. Ileus is managed by treating the cause and supportive measures, not surgery — so distinguishing it from mechanical obstruction avoids an unnecessary operation.
💊KEY POINTS / NUMBERS (viva)- Commonest causes: adhesions (small bowel), colorectal carcinoma (large bowel).
- Initial management = 'drip and suck' (NBM, NG tube, IV fluids, correct electrolytes).
- Surgery for strangulation, obstructed hernia, complete/malignant LBO, or failed conservative treatment.
🔑KEY POINTS TO REMEMBER- Classify by level (small/large bowel), mechanism (mechanical vs paralytic ileus), and simple vs strangulated (blood supply compromised).
- Commonest causes: adhesions (SBO), colorectal cancer (LBO); framework — in lumen / in wall / outside wall.
- Four cardinal features: colicky pain, vomiting (early in SBO, feculent late in LBO), distension (marked in LBO), absolute constipation (early in LBO).
- AXR: central small bowel (valvulae conniventes) vs peripheral large bowel (haustra); CT for level/cause/ischaemia.
- 'Drip and suck' initially; operate for strangulation (continuous pain, peritonism, ↑lactate), obstructed hernia, complete LBO or failed conservative care.
📚SOURCES: Bailey & Love's Short Practice of Surgery; SRB's Manual of Surgery.THE CONCEPT & THE ADENOMA-CARCINOMA SEQUENCE
Colorectal carcinoma is a common adenocarcinoma of the colon and rectum, and its defining biological principle is that it develops through the adenoma-carcinoma sequence: a normal mucosa acquires mutations (classically APC, then KRAS, then p53) and progresses normal epithelium → adenomatous polyp → dysplasia → invasive carcinoma over years. This slow, stepwise evolution through a detectable, removable precursor (the polyp) is exactly what makes screening and polypectomy so effective at preventing the cancer.
RISK FACTORS
Risk rises with age (>50), a diet low in fibre and high in red/processed meat, obesity and smoking. Important high-risk groups are those with inflammatory bowel disease (especially ulcerative colitis), a family history, and the hereditary syndromes — familial adenomatous polyposis (FAP, APC gene) and hereditary non-polyposis colorectal cancer (HNPCC/Lynch syndrome).
CLINICAL FEATURES — SITE DETERMINES THE PICTURE
The presentation depends on where the tumour is, because the calibre and contents of the bowel differ:
Site Typical presentation Right colon (wide lumen, liquid contents) Iron-deficiency anaemia (occult bleeding), weight loss, a right iliac fossa mass, vague pain — presents late Left colon (narrow lumen, solid stool) Change in bowel habit, obstruction, blood/mucus mixed with stool Rectum Bright rectal bleeding, tenesmus, mucus, altered habit, a palpable mass on PR INVESTIGATION & STAGING
Colonoscopy with biopsy is the diagnostic investigation (CT colonography is an alternative). Staging then guides treatment: CT of chest, abdomen and pelvis for distant disease, and MRI of the pelvis for rectal tumours (to assess the circumferential margin and plan therapy). Carcinoembryonic antigen (CEA) is not diagnostic but is a useful baseline and follow-up marker of recurrence. Staging uses Dukes' (A confined to the wall, B through the wall, C nodal spread, D distant metastases) and the TNM system.
SPREAD
Spread is direct (into adjacent structures), lymphatic (to regional nodes), blood-borne via the portal vein to the liver (the commonest site of metastasis), and transcoelomic across the peritoneum.
MANAGEMENT
- Surgery is the mainstay of cure — resection of the tumour-bearing segment with its regional lymph nodes (right or left hemicolectomy, sigmoid colectomy, high anterior resection). Low rectal cancers may need an abdominoperineal resection with a permanent colostomy, whereas higher rectal tumours allow a sphincter-preserving anterior resection with total mesorectal excision (TME).
- Chemotherapy is added as adjuvant therapy for node-positive (Dukes' C) disease.
- Radiotherapy (usually neoadjuvant) is used for rectal cancer to reduce local recurrence.
- Screening (faecal immunochemical testing and colonoscopy) detects early cancers and removes precursor polyps.
💡CLINICAL PEARL: The classic contrast: a right-sided cancer presents with iron-deficiency anaemia and a mass and tends to present late (the caecum is capacious and its contents liquid), whereas a left-sided cancer presents with obstruction and a change in bowel habit (the lumen is narrow and the stool solid). Any adult with unexplained iron-deficiency anaemia or a persistent change in bowel habit needs the colon investigated.HEREDITARY SYNDROMES IN MORE DEPTH
The two hereditary syndromes are worth expanding because they explain many young colorectal cancers. FAP (APC gene) produces thousands of polyps and near-certain cancer, managed by prophylactic colectomy. HNPCC / Lynch syndrome arises from DNA mismatch-repair gene defects, produces relatively few polyps but a high lifetime risk of colorectal (typically right-sided) and other cancers (endometrial, ovarian, gastric). Recognising a suggestive family history triggers genetic assessment and intensive surveillance.
PRINCIPLES OF CANCER SURGERY
Curative surgery follows oncological principles: the tumour-bearing segment is removed with an adequate margin together with its draining lymph nodes along the supplying vessels, which are ligated at their origin. For rectal cancer, total mesorectal excision (TME) — removing the rectum within its intact mesorectal envelope — is the key advance that dramatically reduced local recurrence. Whether the sphincter can be preserved (anterior resection) or must be sacrificed (abdominoperineal resection with a permanent colostomy) depends on how low the tumour lies.
SCREENING & PROGNOSIS
Because the disease evolves slowly through a removable polyp, screening is highly effective — faecal immunochemical testing (FIT) of the population and colonoscopy in higher-risk groups detect early cancers and remove precursor adenomas. Prognosis correlates strongly with stage at diagnosis (Dukes'/TNM), which is why earlier detection saves lives. Even patients with resectable liver metastases may be cured, so metastatic disease is assessed for surgery rather than assumed incurable.
💊KEY POINTS / NUMBERS (viva)- Diagnose by colonoscopy + biopsy; stage with CT (CAP) + MRI pelvis for rectal cancer; CEA for follow-up.
- Dukes': A (in wall), B (through wall), C (nodes), D (distant metastases); liver is the commonest metastatic site.
- Adjuvant chemotherapy for node-positive disease; neoadjuvant radiotherapy for rectal cancer.
🔑KEY POINTS TO REMEMBER- Adenocarcinoma arising via the adenoma-carcinoma sequence (APC→KRAS→p53) — the basis for screening/polypectomy.
- Risk: age, low-fibre/red-meat diet, IBD, FAP and HNPCC/Lynch, family history.
- Right colon → anaemia/mass (late); left colon → obstruction/change in bowel habit; rectum → bleeding, tenesmus.
- Colonoscopy + biopsy diagnose; stage with CT ± MRI pelvis (rectal); CEA for follow-up; Dukes'/TNM; liver commonest metastasis.
- Surgery = segmental resection + nodes (± APR/TME for rectum); adjuvant chemo for node-positive; neoadjuvant radiotherapy for rectal cancer.
📚SOURCES: Bailey & Love's Short Practice of Surgery; SRB's Manual of Surgery.THE CONCEPT
Inflammatory bowel disease (IBD) comprises two chronic, relapsing, immune-mediated conditions — ulcerative colitis (UC) and Crohn's disease (CD). The whole topic becomes manageable once two distinguishing principles are grasped: where the disease occurs and how deep it goes. UC is confined to the colon and is superficial (mucosal); Crohn's can affect anywhere from mouth to anus and is transmural. Almost every clinical difference flows from these two facts.
THE KEY COMPARISON
Feature Ulcerative colitis Crohn's disease Site Colon & rectum only; continuous from rectum proximally Mouth to anus (esp. terminal ileum); skip lesions Depth Mucosa/submucosa Transmural Pattern Continuous Skip lesions, cobblestone mucosa Histology Crypt abscesses; no granulomas Non-caseating granulomas, transmural inflammation Complications Toxic megacolon, higher colorectal cancer risk, PSC Fistulae, strictures, abscesses, perianal disease, malabsorption Smoking Protective (paradox) Worsens the disease CLINICAL FEATURES
UC characteristically causes bloody diarrhoea with mucus, urgency and tenesmus. Crohn's causes abdominal pain, diarrhoea (often non-bloody), weight loss and perianal disease (fissures, fistulae, abscesses), reflecting its transmural, patchy nature. Both may have extraintestinal manifestations — arthritis, uveitis/episcleritis, erythema nodosum, pyoderma gangrenosum, aphthous ulcers, and (in UC) primary sclerosing cholangitis.
INVESTIGATION
Colonoscopy with biopsy establishes the diagnosis and distribution; stool tests exclude infection and measure faecal calprotectin (a marker of gut inflammation); bloods assess anaemia and inflammation. In Crohn's, MRI (small bowel and pelvis) maps disease extent, strictures and fistulae.
MANAGEMENT
- Medical — 5-aminosalicylates (mesalazine) especially for UC; corticosteroids to induce remission in a flare; immunomodulators (azathioprine, methotrexate) and biologics (anti-TNF, e.g. infliximab) to maintain remission; nutritional therapy (important in Crohn's).
- Surgery in UC — a colectomy is curative and is indicated for disease refractory to medical therapy, dysplasia/cancer, or acute complications (toxic megacolon).
- Surgery in Crohn's — not curative and used only for complications (strictures, fistulae, abscesses), with conservative, bowel-preserving resections because disease recurs and repeated resection risks short-bowel syndrome.
💡CLINICAL PEARL: Compress the whole topic into two sentences. UC = mucosal, continuous, colon-only, curable by colectomy, and (paradoxically) smoking-protective. Crohn's = transmural, skip lesions, mouth-to-anus, granulomas, complicated by fistulae and strictures, worsened by smoking, and not cured by surgery.ACUTE SEVERE COLITIS — AN EMERGENCY
A vital point is that IBD can present as an acute emergency. Acute severe ulcerative colitis (bloody diarrhoea with systemic upset) can progress to toxic megacolon — a dilated, thin-walled, non-contractile colon at risk of perforation. It is monitored closely (stool frequency, abdominal X-rays, inflammatory markers) and treated with intravenous steroids and rescue therapy; failure to improve within a few days, or perforation, mandates an emergency colectomy. Recognising this scenario is life-saving.
SURGERY IN DETAIL
The contrasting surgical philosophies deserve emphasis. In UC, because the disease is limited to the colon, removing the colon and rectum is curative — a restorative proctocolectomy with an ileo-anal pouch, or a panproctocolectomy with an end ileostomy. In Crohn's, because disease can recur anywhere, surgery is never curative and is kept minimal (stricturoplasty, limited resection) to preserve bowel length and avoid short-bowel syndrome from repeated operations.
CANCER RISK & SURVEILLANCE
Long-standing colonic IBD (particularly extensive UC, and Crohn's colitis) carries an increased risk of colorectal cancer, arising from areas of dysplasia rather than discrete polyps. Patients therefore enter surveillance colonoscopy programmes after several years of disease, and the finding of dysplasia may itself be an indication for colectomy — a key reason IBD is followed lifelong even when symptoms are controlled.
EXTRAINTESTINAL DISEASE & NUTRITION
The extraintestinal manifestations deserve emphasis because they may dominate the picture or even precede the bowel disease. Some track disease activity (erythema nodosum, peripheral arthritis, episcleritis), while others run an independent course (primary sclerosing cholangitis and ankylosing spondylitis, associated particularly with UC). Nutritional consequences are important in Crohn's, where transmural small-bowel disease and resections cause malabsorption, weight loss, anaemia and (with terminal ileal disease) vitamin B12 and bile-salt malabsorption — so nutritional assessment and support are integral to care.
💊KEY POINTS / NUMBERS (viva)- UC: mucosal, continuous, colon only; crypt abscesses; colectomy is curative; smoking protective.
- Crohn's: transmural, skip lesions, mouth-to-anus; non-caseating granulomas; fistulae/strictures; surgery not curative; smoking worsens.
- Medical ladder: 5-ASA → steroids (flare) → immunomodulators → biologics (anti-TNF).
🔑KEY POINTS TO REMEMBER- IBD = chronic relapsing immune-mediated disease: UC (mucosal, colon only, continuous) vs Crohn's (transmural, mouth-to-anus, skip lesions).
- UC: bloody diarrhoea + mucus, urgency, tenesmus; crypt abscesses, no granulomas; toxic megacolon; higher cancer risk; PSC; smoking protective.
- Crohn's: pain, weight loss, perianal disease; non-caseating granulomas; fistulae/strictures/abscesses; smoking worsens.
- Diagnose with colonoscopy + biopsy, faecal calprotectin, MRI (Crohn's); exclude infection.
- Medical: 5-ASA, steroids, immunomodulators, biologics; surgery curative in UC (colectomy) but not in Crohn's (bowel-preserving, for complications).
📚SOURCES: Bailey & Love's Short Practice of Surgery; Davidson's Principles and Practice of Medicine.THE CONCEPT & TERMINOLOGY
A diverticulum of the colon is an outpouching of mucosa and submucosa herniating through the muscular wall — a 'false' diverticulum (it lacks the muscle layer), in contrast to a 'true' diverticulum containing all layers. It is important to separate the terms: diverticulosis is the mere presence of diverticula (often asymptomatic), diverticular disease is when they cause symptoms, and diverticulitis is inflammation of a diverticulum.
PATHOGENESIS — A DISEASE OF LOW FIBRE
The mechanism explains the site and the epidemiology. A low-fibre diet produces small, hard stools that require high segmental intraluminal pressures to propel. This pressure forces the mucosa to herniate through the weakest points of the colonic wall — where the blood vessels (vasa recta) penetrate the muscle. The sigmoid colon, having the smallest calibre and highest pressures, is by far the commonest site, and this is why the disease is common in low-fibre Western populations.
CLINICAL FEATURES
Most diverticulosis is asymptomatic, discovered incidentally. Symptomatic diverticular disease causes left iliac fossa pain, altered bowel habit and bloating. Acute diverticulitis presents with left iliac fossa pain, fever and localised tenderness — earning it the label 'left-sided appendicitis' — often with a raised white cell count and CRP.
COMPLICATIONS
The complications are high-yield because they are the reason diverticular disease needs surgery:
- Perforation — leading to a localised abscess or generalised (purulent or faeculent) peritonitis.
- Haemorrhage — a common cause of brisk, painless lower gastrointestinal bleeding (an eroded vasa recta).
- Fistula — most classically a colovesical fistula, presenting with pneumaturia and faecaluria and recurrent urinary infections; also colovaginal.
- Stricture — from repeated inflammation, causing large-bowel obstruction.
- Abscess formation.
INVESTIGATION & MANAGEMENT
CT is the investigation of choice in acute diverticulitis (it confirms the diagnosis, detects abscess/perforation, and allows the Hinchey classification). Colonoscopy is performed after an acute episode settles — not during it, because of the perforation risk — mainly to exclude a carcinoma. Management is graded:
- Uncomplicated diverticulitis — antibiotics, bowel rest and analgesia, with a long-term high-fibre diet.
- Abscess — radiologically guided drainage.
- Perforation with peritonitis — emergency surgery, classically Hartmann's procedure (resection of the diseased sigmoid with an end colostomy and closure of the rectal stump).
- Fistula or stricture — elective resection.
💡CLINICAL PEARL: Anchor the topic on three facts: diverticula are false diverticula in the sigmoid colon caused by a low-fibre, high-pressure colon; acute diverticulitis is 'left-sided appendicitis'; and a colovesical fistula causing pneumaturia is the classic fistulating complication. For a perforated diverticulitis with peritonitis, Hartmann's procedure is the emergency operation to name.HINCHEY CLASSIFICATION & DECISIONS
The Hinchey classification grades the severity of perforated diverticulitis and guides management: stage I (a small pericolic abscess) and II (a larger pelvic abscess) can often be managed with antibiotics and radiological drainage, whereas stage III (purulent peritonitis) and IV (faeculent peritonitis) require emergency surgery. This staged approach explains why not every perforation goes straight to theatre, and matches the intervention to the disease.
THE MIMIC OF CARCINOMA
A recurring clinical theme is that diverticular disease and colonic carcinoma can be indistinguishable — both can cause a stricture, altered bowel habit, bleeding or a mass in the sigmoid of an older patient. This is precisely why a colonoscopy is performed once an acute episode settles: to be sure a 'diverticular' stricture is not actually a cancer. Failing to exclude malignancy is the classic error in managing left-sided colonic disease.
MANAGEMENT PRINCIPLES & THE BOTTOM LINE
Modern management is increasingly conservative: many episodes of uncomplicated diverticulitis settle with antibiotics (and some mild cases without them), reserving surgery for complications or recurrent disabling disease. The bottom line is a low-fibre, high-pressure sigmoid that inflames ('left-sided appendicitis') and, when it complicates, does so by perforation, bleeding, fistula or stricture — with Hartmann's procedure the emergency operation for faeculent peritonitis.
💊KEY POINTS / NUMBERS (viva)- CT is the investigation of choice in acute diverticulitis (Hinchey classification); colonoscopy AFTER it settles (exclude cancer).
- Perforated diverticulitis with peritonitis → Hartmann's procedure (resection + end colostomy).
- Colovesical fistula → pneumaturia and faecaluria.
🔑KEY POINTS TO REMEMBER- Diverticula = false (mucosa/submucosa) outpouchings, commonest in the sigmoid, from a low-fibre, high-pressure colon herniating at the vasa recta.
- Diverticulosis (present) vs diverticular disease (symptomatic) vs diverticulitis (inflamed = 'left-sided appendicitis').
- Complications: perforation/peritonitis, haemorrhage (lower GI bleed), fistula (colovesical → pneumaturia), stricture, abscess.
- CT is best in acute disease; colonoscopy after it settles (exclude cancer) — not during (perforation risk).
- Uncomplicated → antibiotics + high-fibre diet; abscess → drainage; perforation/peritonitis → Hartmann's procedure.
📚SOURCES: Bailey & Love's Short Practice of Surgery; SRB's Manual of Surgery.THE CONCEPT
An appendicular mass is the body's attempt to wall off an inflamed or perforating appendix. When appendicitis is not treated in the first day or two, the greater omentum and adjacent loops of small bowel adhere around the inflamed appendix, forming a palpable inflammatory mass in the right iliac fossa — usually about 3–5 days after the onset of symptoms. It represents a localised, contained process rather than free peritonitis, and this containment is what allows initial conservative treatment.
CLINICAL FEATURES
The patient gives a history of a few days of right iliac fossa pain, and on examination there is a tender, ill-defined mass in the right iliac fossa. It must be distinguished from other right iliac fossa masses — a caecal carcinoma, Crohn's disease, or ileocaecal tuberculosis — which is why the colon is later investigated.
MANAGEMENT — THE OCHSNER-SHERREN REGIMEN
The classic management is conservative, the Ochsner-Sherren regimen: intravenous fluids, antibiotics, and close observation, with the size of the mass marked on the skin and the pulse, temperature and mass monitored. Most masses resolve on this regimen. An interval appendicectomy is then often performed about 6–8 weeks later, once the inflammation has settled, and a colonoscopy is done in older patients to exclude an underlying caecal cancer.
WHEN CONSERVATIVE TREATMENT FAILS
The observation is not passive — it watches for deterioration. If the mass enlarges, the pain and fever worsen, or an abscess forms, conservative treatment is abandoned in favour of drainage of the appendicular abscess (radiological or surgical). Signs of spreading peritonitis similarly mandate surgery.
THE RATIONALE FOR CONSERVATISM
The reason for treating an appendicular mass conservatively rather than operating immediately is anatomical: the inflamed appendix is densely adherent within a mass of omentum and bowel, so early surgery is difficult and hazardous — it risks injuring adjacent structures and spreading contained infection. Allowing the inflammation to settle first makes a later (interval) appendicectomy safer and simpler.
THE BOTTOM LINE
An appendicular mass is thus a contained appendicitis, managed conservatively (Ochsner-Sherren) with interval appendicectomy and later colonoscopy in older patients to exclude a caecal cancer.
A NOTE ON THE OLDER PATIENT
In an older patient a right iliac fossa mass must never be assumed to be appendicular without excluding a caecal carcinoma, which can present identically. This is why an interval colonoscopy (or CT colonography) is arranged after the acute episode settles — the mass may resolve, but the underlying diagnosis must be secured.
🔑KEY POINTS TO REMEMBER- Appendicular mass = omentum + bowel walling off an inflamed/perforated appendix, ~3–5 days after onset (localised, contained).
- Tender right iliac fossa mass; distinguish from caecal cancer, Crohn's, ileocaecal TB.
- Managed conservatively (Ochsner-Sherren: IV fluids, antibiotics, observe, mark the mass) — most resolve.
- Interval appendicectomy ~6–8 weeks later; colonoscopy in older patients to exclude caecal cancer.
- Abandon conservative treatment and drain if it forms an abscess, enlarges, or peritonitis develops.
📚SOURCES: Bailey & Love's Short Practice of Surgery; SRB's Manual of Surgery.THE CONCEPT
Meckel's diverticulum is the commonest congenital anomaly of the gastrointestinal tract. It is a 'true' diverticulum (containing all layers of the bowel wall) arising from persistence of the vitellointestinal (omphalomesenteric) duct, which normally disappears in embryonic life. It projects from the antimesenteric border of the ileum, and its importance lies in the complications caused by the ectopic tissue it may contain.
THE 'RULE OF 2s'
Its features are famously summarised by the rule of 2s: it occurs in about 2% of the population, lies about 2 feet (60 cm) from the ileocaecal valve, is about 2 inches long, may contain 2 types of ectopic mucosa (gastric and pancreatic), commonly presents by age 2, and is about twice as common in males.
CLINICAL FEATURES
Most are asymptomatic. Complications arise chiefly from ectopic gastric mucosa, which secretes acid and causes peptic ulceration of the adjacent ileum → painless rectal bleeding (a classic cause of significant lower GI bleeding in a child). It can also cause intestinal obstruction (acting as the lead point of an intussusception or via a band/volvulus), or diverticulitis that mimics acute appendicitis.
DIAGNOSIS & MANAGEMENT
The key diagnostic test for a bleeding Meckel's is a Meckel's (technetium-99m pertechnetate) scan, which is taken up by the ectopic gastric mucosa and localises the diverticulum. Treatment is surgical resection of the diverticulum (with the adjacent ileum if needed); a symptomatic diverticulum is always removed, and an incidentally found one may be removed if it has features suggesting risk.
WHY IT MIMICS OTHER DISEASES
Meckel's diverticulum is called a 'great mimic' because its complications reproduce commoner conditions: peptic ulceration of the ileum resembles other causes of GI bleeding, and Meckel's diverticulitis is clinically indistinguishable from acute appendicitis. A useful surgical rule follows — if the appendix is found to be normal at operation for suspected appendicitis, the surgeon should examine the terminal ileum for a Meckel's diverticulum as the true cause.
THE BOTTOM LINE
Meckel's diverticulum is therefore the commonest congenital GI anomaly (rule of 2s), important for painless bleeding from ectopic gastric mucosa, diagnosed by a technetium scan and treated by resection.
A NOTE ON INCIDENTAL FINDINGS
When a Meckel's diverticulum is found incidentally at surgery for another reason, the decision to remove it is individualised — a narrow-necked or palpably abnormal diverticulum, or one with a suspected band, is usually resected, whereas a broad-based, normal-feeling one in an older patient may be left, since the lifetime risk of complications falls with age.
🔑KEY POINTS TO REMEMBER- Commonest congenital GI anomaly; a true diverticulum from a persistent vitellointestinal duct on the antimesenteric ileum.
- Rule of 2s: 2% of people, 2 feet from ileocaecal valve, 2 inches long, 2 ectopic mucosae (gastric & pancreatic), by age 2, 2:1 male.
- Ectopic gastric mucosa → peptic ulceration → painless rectal bleeding (in children); also obstruction, intussusception, diverticulitis (mimics appendicitis).
- Diagnose bleeding Meckel's with a technetium-99m pertechnetate (Meckel's) scan (detects gastric mucosa).
- Treat by surgical resection.
📚SOURCES: Bailey & Love's Short Practice of Surgery.THE CONCEPT
Intussusception is the telescoping (invagination) of one segment of bowel into the lumen of the immediately distal segment, dragging its mesentery with it. This causes obstruction and, because the mesentery is compressed, progressive venous congestion → ischaemia → and eventually infarction of the intussuscepted bowel if not relieved. The commonest type is ileocolic.
CAUSES — CHILD VS ADULT
The cause differs strikingly with age. In infants (the typical patient, 3 months–2 years) it is usually idiopathic, thought to follow lymphoid hyperplasia of the Peyer's patches after a viral illness, which acts as the lead point. In adults, by contrast, there is almost always a pathological lead point — a polyp, tumour or Meckel's diverticulum — so adult intussusception warrants a search for underlying disease.
CLINICAL FEATURES
The classic infant presentation is episodes of severe colicky pain during which the child draws up the legs and screams, with pallor, alternating with calm intervals. There is vomiting, the passage of 'redcurrant jelly' stool (blood mixed with mucus — a late sign of ischaemia), and a palpable sausage-shaped mass, classically in the right upper quadrant.
DIAGNOSIS & MANAGEMENT
Ultrasound is the investigation of choice, showing the characteristic 'target' or 'doughnut' sign in cross-section. In a stable child without peritonitis, treatment is non-operative reduction by an air (or contrast) enema, which is both diagnostic and therapeutic. Surgery is required if enema reduction fails, if there is peritonitis or perforation, or if a lead point is present (as in adults).
WHY EARLY REDUCTION MATTERS
Prompt treatment matters because a delayed intussusception progresses from simple obstruction to ischaemia and infarction of the trapped bowel, at which point enema reduction becomes unsafe and resection is needed. The passage of 'redcurrant jelly' stool is a warning that ischaemia has begun. This is why a stable child is investigated and reduced urgently, and why peritonitis contraindicates enema reduction.
THE BOTTOM LINE
Intussusception is telescoping bowel — idiopathic in infants, lead-point-driven in adults — recognised by colicky pain, redcurrant-jelly stool and a target sign on ultrasound, and reduced by air enema unless a lead point or peritonitis demands surgery.
A NOTE ON ADULT INTUSSUSCEPTION
Adult intussusception differs fundamentally from the infantile form: because a pathological lead point (usually a tumour or polyp) is almost always present, enema reduction is inappropriate and surgical resection is the rule, both to relieve the obstruction and to remove and examine the causative lesion. Any adult with intussusception is therefore investigated for an underlying neoplasm.
🔑KEY POINTS TO REMEMBER- Intussusception = telescoping of bowel into the distal segment (usually ileocolic) → obstruction + ischaemia.
- Infants: idiopathic (lymphoid hyperplasia after viral illness); adults: pathological lead point (polyp, tumour, Meckel's).
- Colicky pain (child draws up legs), vomiting, 'redcurrant jelly' stool, sausage-shaped mass.
- Ultrasound shows 'target'/'doughnut' sign.
- Treat by air/contrast enema reduction (stable child); surgery if it fails, peritonitis/perforation, or a lead point.
📚SOURCES: Bailey & Love's Short Practice of Surgery.THE CONCEPT
A sigmoid volvulus is a twisting of the sigmoid colon around its mesenteric axis, producing a closed-loop large-bowel obstruction. Because both ends of the loop are occluded, the trapped segment distends massively, and twisting of the mesentery threatens its blood supply — so ischaemia and perforation can follow. It is the commonest type of colonic volvulus and a recognised cause of large-bowel obstruction.
PREDISPOSING FACTORS
It typically affects the elderly, constipated, and institutionalised (including patients with neurological or psychiatric conditions), in whom a long, redundant sigmoid loop on a narrow mesentery and chronic loading predispose the bowel to twist. A high-fibre diet and chronic constipation contribute to the redundant, loaded colon.
CLINICAL FEATURES & DIAGNOSIS
There is gross abdominal distension (often dramatic and rapid), colicky lower abdominal pain, and absolute constipation. The plain abdominal X-ray is characteristic, showing a hugely dilated loop arising from the pelvis — the 'coffee-bean' or 'omega' sign — pointing towards the right upper quadrant. CT confirms the diagnosis and assesses for ischaemia (the 'whirl' sign of the twisted mesentery).
MANAGEMENT
If there is no sign of ischaemia or perforation, treatment is endoscopic decompression — passing a sigmoidoscope (or flatus tube) to untwist the loop, which releases a dramatic rush of flatus and stool and deflates the bowel. Because recurrence is common, elective sigmoid colectomy is often considered. Emergency surgery (sigmoid colectomy, e.g. Hartmann's) is required if there is ischaemia, perforation, or failed endoscopic decompression.
PATHOPHYSIOLOGY OF THE CLOSED LOOP
The danger of sigmoid volvulus lies in its closed-loop nature: with both ends of the loop occluded and the mesentery twisted, the segment cannot decompress and its blood supply is progressively cut off, so gangrene and perforation can develop rapidly. This is why any sign of ischaemia (peritonism, systemic upset, blood on the flatus tube, or CT changes) converts an endoscopic problem into an emergency operation.
THE BOTTOM LINE
Sigmoid volvulus is a closed-loop obstruction of a redundant sigmoid in the elderly, recognised by the coffee-bean sign, decompressed endoscopically when viable, and resected when ischaemic or recurrent.
A NOTE ON CAECAL VOLVULUS
Sigmoid volvulus should be contrasted with the less common caecal volvulus, which occurs in younger patients with an abnormally mobile caecum, presents as a small-bowel-type obstruction with a dilated caecum displaced to the left upper quadrant, and — unlike sigmoid volvulus — usually requires surgery (right hemicolectomy) rather than endoscopic decompression.
🔑KEY POINTS TO REMEMBER- Sigmoid volvulus = twisting of the sigmoid on its mesentery → closed-loop large-bowel obstruction (± ischaemia/perforation).
- Typically elderly, constipated, institutionalised, with a long redundant sigmoid loop.
- Gross distension, colicky pain, absolute constipation; AXR shows a 'coffee-bean'/'omega' loop from the pelvis.
- No ischaemia → endoscopic decompression (sigmoidoscope/flatus tube); recurrence common → elective sigmoid colectomy.
- Ischaemia/perforation/failed decompression → emergency surgery (sigmoid colectomy/Hartmann's).
📚SOURCES: Bailey & Love's Short Practice of Surgery.THE CONCEPT
A stoma is a surgically created opening that brings a segment of bowel to the surface of the abdominal wall, allowing intestinal contents to be diverted into an external appliance. The two main intestinal stomas are the colostomy (an opening of the colon) and the ileostomy (an opening of the ileum), and being able to distinguish them clinically is a classic exam and ward skill.
DISTINGUISHING COLOSTOMY FROM ILEOSTOMY
Feature Colostomy Ileostomy Site Usually left iliac fossa Usually right iliac fossa Surface Flush with the skin Spouted (protrudes) Output Solid/formed faeces Liquid, enzyme-rich effluent The spout of an ileostomy is deliberate: the small-bowel effluent is liquid and rich in digestive enzymes, so protruding the stoma protects the surrounding skin from corrosive contact, whereas the solid colonic output of a colostomy allows it to be flush.
INDICATIONS & TYPES
Stomas are formed to divert faeces (protecting a distal anastomosis — a defunctioning loop stoma), for decompression, or as a permanent outlet after removal of the distal bowel (e.g. an end colostomy after an abdominoperineal resection or Hartmann's procedure). An end stoma has one opening; a loop stoma has two (and is typically temporary).
COMPLICATIONS
Complications are commonly examined and include skin excoriation, retraction, prolapse, stenosis, parastomal hernia, ischaemia/necrosis, bleeding, and — particularly with a high-output ileostomy — dehydration and electrolyte loss. Good stoma-nurse support, correct siting and appliance care prevent many of these.
SITING & QUALITY OF LIFE
Correct pre-operative siting of a stoma by a stoma nurse — away from the waistline, bony prominences, scars and skin creases, where the patient can see and reach it — is crucial to a well-functioning stoma and to quality of life. Poor siting leads to leakage, skin problems and appliance failure, which is why elective stomas are marked before surgery and patients receive dedicated stoma-care education.
THE BOTTOM LINE
The examinable essence is distinguishing a flush, LIF, solid-output colostomy from a spouted, RIF, liquid-output ileostomy, and knowing the indications and complications of each.
REVERSAL & PERMANENCE
Whether a stoma is temporary or permanent is an important counselling point. A defunctioning loop stoma protecting a distal anastomosis is usually reversed after the anastomosis has healed, whereas an end colostomy after an abdominoperineal resection is permanent. Patients need clear information about which they have and, where relevant, the timing and risks of reversal surgery.
🔑KEY POINTS TO REMEMBER- Stoma = bowel opened onto the abdominal wall into an appliance; colostomy (colon) vs ileostomy (ileum).
- Colostomy: usually LIF, flush, solid output; ileostomy: usually RIF, spouted (protects skin), liquid output.
- Indications: defunction/protect an anastomosis, diversion, decompression, or permanent (end colostomy after APR/Hartmann's).
- End stoma (one opening) vs loop stoma (two, usually temporary).
- Complications: skin excoriation, retraction, prolapse, stenosis, parastomal hernia, ischaemia; high-output ileostomy → dehydration.
📚SOURCES: Bailey & Love's Short Practice of Surgery.THE CONCEPT
Familial adenomatous polyposis (FAP) is an autosomal dominant inherited condition caused by a mutation in the APC tumour-suppressor gene (chromosome 5). Its hallmark is the development of hundreds to thousands of adenomatous polyps carpeting the colon and rectum, beginning in adolescence. It is the archetypal example of an inherited colorectal cancer syndrome and demonstrates the adenoma-carcinoma sequence at its most dramatic.
THE CANCER RISK
Because each of these numerous adenomas can progress to carcinoma, the risk of colorectal cancer approaches 100% by around the age of 40 if the colon is not removed. This near-certainty of malignancy is what makes FAP a prophylactic surgical disease — the colon is removed before cancer inevitably develops.
SCREENING & MANAGEMENT
Management centres on identification and prevention. Affected families undergo genetic testing, and gene carriers begin surveillance colonoscopy from their early teens. The definitive treatment is prophylactic surgery — total colectomy or proctocolectomy, often with an ileo-anal pouch — performed once polyps appear, to remove the organ at risk. Upper GI surveillance is also needed because of duodenal and ampullary adenomas.
ASSOCIATED SYNDROMES
Two named variants are worth knowing: Gardner's syndrome (FAP with osteomas, desmoid tumours and epidermoid cysts) and Turcot's syndrome (FAP with central nervous system tumours). These extracolonic features can be the clue to the underlying polyposis.
CONTRAST WITH LYNCH SYNDROME
It is worth contrasting FAP with the other major hereditary colorectal cancer syndrome, HNPCC (Lynch syndrome): Lynch is caused by mismatch-repair gene defects, produces few polyps (not thousands) but a high risk of colorectal (often right-sided) and extracolonic cancers (endometrial, ovarian). FAP is polyp-count driven and APC-based; Lynch is repair-defect driven — a distinction examiners frequently probe.
THE BOTTOM LINE
FAP is an autosomal-dominant APC-gene polyposis with near-certain colorectal cancer, managed by genetic testing, surveillance and prophylactic colectomy, with Gardner's and Turcot's as its named variants.
A NOTE ON CHEMOPREVENTION & TIMING
In FAP the timing of prophylactic surgery is judged by the polyp burden on surveillance, balancing cancer prevention against operating on a young person; NSAIDs/COX-2 inhibitors have been studied to slow polyp growth but do not replace colectomy. Lifelong surveillance of the retained rectum (if a pouch is not formed) and of the upper GI tract continues after surgery.
🔑KEY POINTS TO REMEMBER- FAP = autosomal dominant, APC tumour-suppressor gene mutation (chromosome 5).
- Hundreds–thousands of colorectal adenomatous polyps from adolescence.
- ~100% risk of colorectal cancer by ~40 if untreated → a prophylactic surgical disease.
- Genetic testing + surveillance colonoscopy from the teens; prophylactic (procto)colectomy ± ileo-anal pouch; upper-GI surveillance (duodenal/ampullary tumours).
- Variants: Gardner's (osteomas, desmoids) and Turcot's (CNS tumours).
📚SOURCES: Bailey & Love's Short Practice of Surgery.THE CONCEPT
Pseudomembranous colitis is a colitis caused by overgrowth of the toxin-producing bacterium Clostridioides difficile. The mechanism is a disturbed ecosystem: antibiotics disrupt the normal protective gut flora, allowing C. difficile to proliferate and release toxins A and B, which damage the colonic mucosa and produce the characteristic inflammatory 'pseudomembranes'. The classic culprit antibiotics are clindamycin, cephalosporins and fluoroquinolones, though almost any antibiotic can be responsible.
CLINICAL FEATURES
It presents with profuse watery diarrhoea, crampy abdominal pain, fever and a raised white cell count, typically during or shortly after a course of antibiotics, often in a hospitalised or elderly patient. At colonoscopy the mucosa is studded with raised yellowish-white plaques (pseudomembranes). Severe disease can progress to toxic megacolon and perforation.
DIAGNOSIS & MANAGEMENT
Diagnosis is by detecting C. difficile toxin (or its gene by PCR) in the stool. Management begins with stopping the offending antibiotic where possible and instituting infection-control measures (isolation, hand hygiene with soap and water). Specific treatment is oral vancomycin or fidaxomicin (oral metronidazole for milder cases). Recurrent disease may be treated with a faecal microbiota transplant to restore normal flora, and fulminant colitis with megacolon may require colectomy.
PREVENTION & INFECTION CONTROL
Because C. difficile is a spore-forming, easily transmitted hospital pathogen, prevention is central: prudent 'antibiotic stewardship' (avoiding unnecessary broad-spectrum antibiotics), isolating affected patients, and hand-washing with soap and water (alcohol gel does not kill the spores). These measures limit both individual disease and hospital outbreaks, making pseudomembranous colitis as much an infection-control topic as a clinical one.
THE BOTTOM LINE
Pseudomembranous colitis is antibiotic-associated C. difficile toxin colitis, diagnosed on stool toxin, treated by stopping the antibiotic and giving oral vancomycin/fidaxomicin with strict infection control.
A NOTE ON SEVERITY ASSESSMENT
Severity is graded (by white cell count, creatinine, temperature and albumin) because it guides both drug choice and the need for surgery. Fulminant disease with toxic megacolon, perforation or shock is a surgical emergency requiring colectomy, whereas most cases respond to medical therapy — so recognising the severe end of the spectrum early is what prevents disaster.
🔑KEY POINTS TO REMEMBER- Pseudomembranous colitis = C. difficile toxin overgrowth after antibiotics disrupt normal flora (classically clindamycin, cephalosporins, fluoroquinolones).
- Profuse watery diarrhoea, cramps, fever, raised WCC; yellow pseudomembranes at colonoscopy; can cause toxic megacolon/perforation.
- Diagnose by stool C. difficile toxin/PCR.
- Stop the offending antibiotic + infection control (isolation, soap-and-water hygiene); treat with oral vancomycin or fidaxomicin (metronidazole if mild).
- Recurrent disease → faecal microbiota transplant; fulminant → colectomy.
📚SOURCES: Bailey & Love's Short Practice of Surgery; Davidson's Principles and Practice of Medicine.