APPENDICITIS

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APPENDICITIS

Overview & Epidemiology

Appendicitis is the most common intra-abdominal surgical emergency, affecting ~1 per 1,000 adults annually worldwide. Lifetime risk is 7–10% (8.7% men, 6.9% women). In the United States, ~400,000 cases are diagnosed per year, with 16–40% presenting with perforation. Peak incidence is ages 9–12 years; it is uncommon under age 5 but carries the highest perforation rate in that group (>50% ruptured at surgery).

Current Surgical Therapy 14e | Goldman-Cecil Medicine | Rosen's Emergency Medicine

Anatomy

The appendix is an ~9 cm long, 0.6 cm wide vermiform ("worm-shaped") hollow structure arising from the terminal cecum, at the convergence of the three taenia coli. While the base is consistently cecal, the tip position varies widely:

Retrocecal (most common, ~65%)
Pelvic / subcecal
Pre-ileal / post-ileal

This positional variability explains the diversity of clinical presentations. Blood supply: appendiceal artery, a branch of the ileocolic artery (branch of superior mesenteric artery).

Variations in position of the vermiform appendix

Variations in positions of the vermiform appendix — Current Surgical Therapy 14e

Pathophysiology

The central mechanism is luminal obstruction → bacterial overgrowth → progressive ischemia → perforation.

Causes of obstruction:

Cause	Notes
Fecalith / appendicolith	Most common
Lymphoid hyperplasia	Common in children (viral infections)
Neoplasm	Carcinoid, mucocele
Parasites	Enterobius, Ascaris
Foreign body	Less common

Sequence of events:

Obstruction → increased intraluminal pressure
Mucus accumulation, bacterial overgrowth (E. coli, B. fragilis, Klebsiella, Streptococcus, Enterococcus, Pseudomonas)
Venous congestion → distension → visceral pain (periumbilical)
Arterial ischemia → necrosis → gangrene
Perforation → local abscess or diffuse peritonitis

Children have thinner appendiceal walls and underdeveloped omentum → perforation occurs earlier and diffuse peritonitis develops more readily.

Current Surgical Therapy 14e

Clinical Features

Classic Presentation

Anorexia (often earliest symptom)
Nausea and vomiting
Periumbilical pain initially (visceral, colicky) → migrates to RLQ (McBurney's point) within hours as parietal peritoneum becomes involved
Low-grade fever (develops later; high fever suggests perforation/abscess)
Progressive worsening over 24–72 hours

McBurney's point: two-thirds of the distance from the umbilicus to the right anterosuperior iliac spine.

Physical Examination Signs

Sign	How to Elicit	Significance
McBurney's tenderness	Direct palpation at McBurney's point	Most reliable
Rovsing's sign	Palpation of LLQ causes RLQ pain	Peritoneal irritation
Psoas sign	Pain with extension of right hip (patient prone) or flexion against resistance	Retrocecal appendix
Obturator sign	Pain with internal rotation of flexed right hip	Pelvic appendix
Dunphy's sign	Increased RLQ pain with coughing	Peritonitis
Heel-tap sign	RLQ pain when patient drops from tiptoes	Peritoneal irritation
Rebound tenderness	Sudden release of pressure causes pain	Peritoneal irritation
Guarding / rigidity	Involuntary muscle spasm	Peritonitis

Important caveats: Rovsing, psoas, and obturator signs have poor sensitivity/specificity, especially in young children. Classic signs may be absent in retrocecal appendicitis, elderly patients, immunosuppressed patients, and pregnant women.

Rosen's Emergency Medicine | Textbook of Family Medicine 9e

Differential Diagnosis

Surgical causes: Intestinal obstruction, intussusception, acute cholecystitis, Meckel's diverticulitis, mesenteric adenitis, ovarian torsion, ectopic pregnancy

Gynecological: Pelvic inflammatory disease, ovarian cyst (ruptured/torsion), endometriosis, mittelschmerz

Medical/other: Urinary tract infection, right ureteral stone, psoas abscess, right-sided pneumonia, Crohn's disease, gastroenteritis, constipation

Goldman-Cecil Medicine, Table 128-1

Diagnostic Workup

Laboratory Tests

No single test is diagnostic. Typical findings:

WBC >10,000/μL (in 87–92% of cases) but <18,000/μL unless perforation has occurred; left shift
CRP elevated (>0.6 mg/dL sensitive; highly elevated suggests perforation/abscess)
Procalcitonin: elevated with complicated appendicitis
Urinalysis: mild sterile pyuria (<5–10 WBC/hpf) possible due to ureteral inflammation; does not exclude appendicitis
β-hCG: mandatory in women of reproductive age to exclude ectopic pregnancy

Clinical Scoring Systems

Alvarado Score (MANTRELS):

Feature	Points
Migration of pain to RLQ	1
Anorexia	1
Nausea/vomiting	1
RLQ tenderness	2
Rebound tenderness	1
Elevated temperature (>37.3°C)	1
Leukocytosis (WBC >10,000)	2
Left shift	1
Total	10

Interpretation: ≤4 = unlikely; 5–6 = possible; 7–8 = probable; 9–10 = very likely.

Other validated systems: Pediatric Appendicitis Score (PAS), Adult Appendicitis Score, Appendicitis Inflammatory Response (AIR) score.

Imaging

Modality	Sensitivity	Specificity	Notes
CT (multidetector, low-dose)	≥94%	≥94%	Preferred in adults and obese patients; can detect perforation and complications
Ultrasound	~83%	~93%	First-line in children and pregnant women; non-compressible appendix >6 mm is diagnostic; operator-dependent
MRI	Comparable to CT	Comparable to CT	Preferred in pregnancy (avoids radiation); good alternative
Plain X-ray	Low	Low	Not diagnostic; may show appendicolith, ileus, RLQ soft tissue density

CT findings in appendicitis:

Dilated appendix >6 mm diameter
Appendiceal wall thickening and enhancement
Periappendiceal fat stranding
Appendicolith (seen in ~30%)
Periappendiceal abscess (with perforation)

CT scan showing dilated appendix with fat stranding

Contrast-enhanced CT: distended, fluid-filled appendix with fat stranding in the right iliac fossa

Coronal CT showing thickened appendix with fat stranding

Coronal CT: thickened, dilated appendix (~1 cm) with periappendiceal fat stranding (arrows)

RLQ ultrasound in a 10-year-old: dilated fluid-filled tubular structure with echogenic appendicolith — consistent with acute appendicitis

Goldman-Cecil Medicine | Current Surgical Therapy 14e | Rosen's Emergency Medicine

Classification

Type	Features
Simple (uncomplicated)	Inflamed but intact; no necrosis, perforation, or abscess
Gangrenous	Necrosis of appendiceal wall; almost always associated with luminal obstruction
Perforated	Full-thickness rupture; risk of peritonitis or abscess
Phlegmon / Abscess	Walled-off perforation; mass palpable in RLQ

Management

Preoperative

IV fluids and electrolyte correction
NPO
Preoperative antibiotics (reduce infectious complications in uncomplicated disease):
- Cefotetan 2 g IV, or Cefoxitin 2 g IV (3 postoperative doses for uncomplicated disease)
- Piperacillin-tazobactam or ticarcillin-clavulanic acid for complicated/perforated
- Target: E. coli, Bacteroides (gram-negative aerobes + anaerobes)

Operative Management

Laparoscopic appendectomy is now the standard of care for most cases:

Lower rate of postoperative complications vs. open
Faster return to normal activity and diet
Appropriate for: uncomplicated and most complicated appendicitis

Open appendectomy (McBurney's / Gridiron incision):

Preferred when perforation is evident preoperatively
McBurney's incision: oblique through McBurney's point; muscle-splitting (gridiron)
Remains essential skill for surgeons

Interval appendectomy: For patients who present with phlegmon/abscess after >5 days of symptoms → nonoperative management first (IV antibiotics ± percutaneous drainage by interventional radiology), followed by interval appendectomy at 6–8 weeks.

Nonoperative (Antibiotic-Only) Management

Growing evidence supports antibiotics alone for uncomplicated appendicitis:

~80–90% symptom resolution within 24–48 hours
2025 WSES Jerusalem Guidelines and 2024 SAGES Guidelines acknowledge this as a viable alternative
Recurrence rate ~25–40% at 5 years (higher in children)
Contraindicated if: fecalith/appendicolith present, perforation, immunocompromised, unable to comply with follow-up
Most surgeons still prefer operative management as definitive treatment
Current Surgical Therapy 14e | Goldman-Cecil Medicine | SAGES 2024 [PMID: 38740595] | WSES 2025 [PMID: 41604201]

Complications

Complication	Features
Perforation	Increases mortality 0.0002% → 3%; morbidity 3% → 47%
Peritonitis	Diffuse or localized; requires broad-spectrum antibiotics + surgery
Periappendiceal abscess	Walled-off perforation; drain percutaneously if accessible
Wound infection	More common after open or contaminated surgery
Ileus / adhesions	Post-surgical bowel obstruction
Pylephlebitis	Septic portal vein thrombosis (rare but serious)
Stump appendicitis	Inflammation of residual appendiceal stump after appendectomy

Special Populations

Children

Perforation rate inversely correlates with age; >50% perforation rate in children <5 years
US and MRI preferred (avoid radiation)
Nonoperative management acceptable in select cases; recurrence up to 40%
Same-day discharge possible after laparoscopic appendectomy in early disease

Pregnancy

Most common surgical emergency in pregnancy (same incidence as non-pregnant)
Diagnosis challenging: displaced appendix (tip moves to RUQ by third trimester in <25% of cases), physiologic leukocytosis and elevated ESR
MRI preferred imaging (avoids fetal radiation)
Perforation → increased risk of sepsis, fetal mortality, preterm labor
Laparoscopic appendectomy safe throughout all trimesters

Elderly

Atypical presentation common; diagnosis often delayed
Higher perforation rate at presentation (~70%)
Higher mortality and morbidity

Prognosis

Uncomplicated appendicitis: mortality ~0.0002%; full recovery expected
Perforated appendicitis: mortality ~3%; morbidity ~47%
Laparoscopic vs. open: laparoscopic carries lower wound infection rate, shorter hospital stay

Recent Guidelines (2024–2025)

Guideline	Key Recommendation
SAGES 2024 [PMID: 38740595]	Laparoscopic appendectomy preferred; antibiotics-first is a valid option for uncomplicated disease in selected patients
WSES Jerusalem Guidelines 2025 [PMID: 41604201]	Updated diagnostic and management algorithms; CT preferred for adults; nonoperative management supported for uncomplicated, fecalith-free appendicitis

Definition Etiology Pathophysiology ( chart form) Clinical features Types Diagnosis/ investigation Management ( table form) Medical management Surgical management Algorithm to approach appendicitis (chart form) with arrow Of appendicitis

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APPENDICITIS — Structured Clinical Reference

1. DEFINITION

Appendicitis is an acute inflammation of the vermiform appendix — a blind-ended tubular structure arising from the cecum — resulting from luminal obstruction, bacterial overgrowth, and progressive ischemic injury to the appendiceal wall.

It is the most common intra-abdominal surgical emergency worldwide, responsible for ~300,000–400,000 hospitalizations annually in the United States, with a lifetime risk of 6–10% in the general population.

Sabiston Textbook of Surgery | Goldman-Cecil Medicine

2. ETIOLOGY

Primary Cause: Luminal Obstruction

Cause	Details
Fecalith / Appendicolith	Most common; hardened stool or calcified concretion; ~1/3 of cases
Lymphoid hyperplasia	Common in children/adolescents following viral infections (adenovirus, EBV)
Neoplasms	Carcinoid tumor, mucinous adenocarcinoma, carcinoma
Parasites	Enterobius vermicularis (pinworm), Ascaris lumbricoides
Foreign body	Ingested material, vegetable seeds, barium
Fecal stasis	Low-fiber, high-fat (Western) diet implicated epidemiologically
Stricture / adhesion	Post-inflammatory scarring

Bacteriology (polymicrobial)

Escherichia coli
Bacteroides fragilis
Klebsiella pneumoniae
Enterococcus spp.
Pseudomonas aeruginosa
Streptococcus spp.

Sabiston Textbook of Surgery | Current Surgical Therapy 14e

3. PATHOPHYSIOLOGY (Flow Chart)

LUMINAL OBSTRUCTION
(fecalith, lymphoid hyperplasia, neoplasm, parasite)
            │
            ▼
INCREASED INTRALUMINAL PRESSURE
(mucus secretion + bacterial gas production continue)
            │
            ▼
VENOUS CONGESTION & LYMPHATIC OBSTRUCTION
(visceral afferent nerve fibers stretched)
            │
            ▼
VAGUE PERIUMBILICAL / EPIGASTRIC PAIN
(T10 dermatome, colicky, visceral)
            │
            ▼
BACTERIAL OVERGROWTH & MUCOSAL ISCHEMIA
(E. coli, B. fragilis, Klebsiella, Pseudomonas)
            │
            ▼
TRANSMURAL INFLAMMATION
(appendiceal wall becomes full-thickness inflamed)
            │
            ▼
PARIETAL PERITONEUM INVOLVED
            │
            ▼
LOCALIZED SOMATIC PAIN → RLQ (McBurney's point)
+ Fever, guarding, rigidity
            │
            ▼
    ┌───────┴────────┐
    ▼                ▼
UNCOMPLICATED     ARTERIAL ISCHEMIA
APPENDICITIS      → FULL-THICKNESS NECROSIS
(inflamed but         (Gangrenous appendicitis)
 intact)                    │
                            ▼
                      PERFORATION
                   ┌──────┴──────┐
                   ▼             ▼
           LOCALIZED          FREE PERFORATION
           ABSCESS /          (Diffuse peritonitis,
           PHLEGMON           sepsis, death)

Sabiston Textbook of Surgery | Current Surgical Therapy 14e

4. CLINICAL FEATURES

Symptoms

Symptom	Description
Anorexia	Earliest and most consistent symptom
Periumbilical pain	Initial visceral pain — vague, colicky
Migration of pain to RLQ	Hallmark; occurs over 12–24 h as parietal peritoneum becomes involved
Nausea & vomiting	Usually follows pain onset
Low-grade fever	37.5–38.5°C; high fever (>39°C) suggests perforation
Constipation / diarrhea	Variable; tenesmus possible with pelvic appendix

Signs

Sign	Method	Significance
McBurney's tenderness	Direct palpation 2/3 from umbilicus to ASIS	Most reliable RLQ finding
Guarding / rigidity	Involuntary abdominal wall spasm	Peritoneal irritation
Rebound tenderness (Blumberg's)	Sudden release of deep pressure → pain	Peritonitis
Rovsing's sign	LLQ palpation → RLQ pain	Refers peritoneal irritation
Psoas sign	Pain on right hip extension (patient prone) or active flexion against resistance	Retrocecal appendix
Obturator sign	Pain with internal rotation of flexed right hip	Pelvic appendix
Dunphy's (cough) sign	RLQ pain increased by coughing	Peritonitis
Heel-drop test	Patient drops from tiptoes → RLQ pain	Peritoneal irritation
Rigidity / Board-like abdomen	Involuntary muscle guarding	Perforated / diffuse peritonitis

Rosen's Emergency Medicine | Textbook of Family Medicine 9e | Sabiston Textbook of Surgery

5. TYPES / CLASSIFICATION

By Acuity

Type	Features
Acute appendicitis	Evolves over hours to days; most common presentation
Chronic / Recurrent appendicitis	Symptoms spanning weeks to months; low-grade, intermittent pain

By Severity (most clinically important)

Type	Pathology	Key Features
Simple (Uncomplicated)	Inflamed appendix, wall intact, no necrosis	RLQ pain, fever, leukocytosis; no perforation
Gangrenous	Full-thickness wall necrosis	More severe pain; almost always associated with fecalith; pre-perforation state
Perforated	Transmural rupture	High fever, peritonism, sepsis; two subtypes below
Appendiceal Phlegmon	Contained inflammatory mass	Palpable RLQ mass; present after ≥5 days of symptoms
Periappendiceal Abscess	Walled-off pus collection	Mass, swinging fever; amenable to percutaneous drainage
Diffuse Peritonitis	Free perforation, peritoneal soilage	Generalized rigidity, sepsis, high mortality

Sabiston Textbook of Surgery | Current Surgical Therapy 14e

6. DIAGNOSIS / INVESTIGATIONS

Clinical Scoring: Alvarado Score (MANTRELS)

Feature	Score
Migration of pain to RLQ	1
Anorexia	1
Nausea / vomiting	1
Tenderness in RLQ	2
Rebound tenderness	1
Elevated temperature (>37.3°C)	1
Leukocytosis (WBC >10,000)	2
Shift to left (neutrophilia)	1
Total	10

Interpretation: ≤4 = Appendicitis unlikely | 5–6 = Possible | 7–8 = Probable | 9–10 = Highly likely

Other scores: Pediatric Appendicitis Score (PAS), Appendicitis Inflammatory Response (AIR) Score, Adult Appendicitis Score

Laboratory Investigations

Test	Expected Finding	Notes
WBC count	>10,000/μL; usually <18,000	Elevated in 87–92%; left shift (neutrophilia)
CRP	Elevated (>0.6 mg/dL)	Highly elevated → perforation/abscess
Procalcitonin	Elevated	Indicates complicated/perforated disease
Urinalysis	Mild sterile pyuria possible	≤5–10 WBC/hpf; bacteria absent; from ureteral irritation
β-hCG (serum/urine)	Negative	Mandatory in all women of reproductive age
Blood cultures	Positive in sepsis	Needed if systemic infection suspected
Electrolytes / BMP	Disturbances with vomiting	Baseline for surgical planning
LFTs / Lipase	Normal (helps exclude biliary/pancreatic)	Part of differential workup

Imaging Investigations

Modality	Sensitivity	Specificity	When to Use
CT Abdomen/Pelvis (MDCT)	≥94%	≥94%	Gold standard in adults; low-dose (2 mSv); detects perforation, abscess, alternative diagnoses
Ultrasound (RLQ)	~83%	~93%	First-line in children and pregnant women; non-compressible appendix >6 mm diagnostic; operator-dependent
MRI Abdomen	~95%	~95%	Preferred in pregnancy (no radiation); safe, accurate
Plain X-ray (AXR)	Low	Low	Not routinely used; may show appendicolith, air-fluid levels, RLQ soft tissue density

CT Diagnostic Criteria:

Appendix diameter >6 mm
Appendiceal wall thickening + enhancement
Periappendiceal fat stranding
Appendicolith (30% of cases)
Periappendiceal fluid / abscess (with perforation)
"Target sign": thickened, fluid-filled appendix (sagittal view)

CT of acute appendicitis — target sign and fat stranding

CT abdomen: (A) Sagittal — thickened, fluid-filled appendix (target sign); (B) Coronal — elongated appendix with fat stranding — Sabiston Textbook of Surgery

Ultrasound appendicitis with appendicolith

RLQ ultrasound: dilated fluid-filled tubular structure + echogenic appendicolith — Current Surgical Therapy 14e

Goldman-Cecil Medicine | Sabiston Textbook of Surgery | Current Surgical Therapy 14e

7. MANAGEMENT (Table Form)

Overview by Type

Type of Appendicitis	Management Strategy
Uncomplicated (simple)	Laparoscopic appendectomy OR antibiotics-first (shared decision making)
Gangrenous	Laparoscopic appendectomy (urgent)
Perforated with diffuse peritonitis	Emergency open or laparoscopic appendectomy + peritoneal lavage
Perforated with abscess (<5 days)	Laparoscopic appendectomy + drainage
Phlegmon / Abscess (>5 days symptoms)	Nonoperative: IV antibiotics ± percutaneous drain → Interval appendectomy 6–8 weeks
Chronic/recurrent	Elective laparoscopic appendectomy

A. MEDICAL MANAGEMENT

Component	Details
IV Fluid Resuscitation	Normal saline or Lactated Ringer's to correct dehydration and electrolyte imbalances
NPO	Nothing by mouth in anticipation of surgery or while monitoring
Analgesia	IV opioids (morphine, fentanyl) — does NOT mask diagnosis; provide adequate pain relief
Antiemetics	Ondansetron, metoclopramide for nausea/vomiting
Antipyretics	Paracetamol / NSAIDs for fever management
Preoperative antibiotics	Single dose within 60 min of incision (reduces surgical site infections)

Antibiotic Regimens

Setting	First-Line	Alternatives
Uncomplicated (prophylaxis)	Cefotetan 2 g IV OR Cefoxitin 2 g IV	Cefazolin + metronidazole
Complicated / Perforated	Piperacillin-tazobactam 3.375 g IV q6h	Ticarcillin-clavulanate; Meropenem (severe)
Antibiotics-only (nonoperative)	Ertapenem 1 g IV daily OR Ceftriaxone + metronidazole	Amoxicillin-clavulanate (oral step-down)
Penicillin allergy	Ciprofloxacin + metronidazole	Aztreonam + metronidazole

Duration:

Uncomplicated: single preoperative dose (3 doses post-op max)
Complicated/perforated: 3–5 days IV then consider oral step-down based on clinical response
Nonoperative (antibiotics-only): 7–10 days (IV 24–48 h → oral)

Nonoperative (Antibiotics-Only) — Indications & Criteria

Factor	Suitable for Nonoperative	NOT Suitable
Appendicolith	No	Yes (higher failure/complication rate)
Imaging	Uncomplicated, no abscess	Perforation, free air, abscess
Age	Adults, select pediatric	Very young children
Recurrence risk	Counseled (~25–40% at 5 years)	Refused by patient
Comorbidities	Low surgical risk prefers nonop	High surgical risk

Sabiston Textbook of Surgery (CODA trial, APPAC trial) | Current Surgical Therapy 14e

B. SURGICAL MANAGEMENT

Laparoscopic Appendectomy (Standard of Care)

Step	Details
Position	Supine; left arm tucked; possible reverse Trendelenburg + right side up
Access	Veress needle (closed) or Hasson technique (open) through umbilicus
Insufflation	CO₂ to 12–15 mmHg
Port placement	Umbilical camera port (10–12 mm) + 2 working ports (5 mm) in LLQ / suprapubic
Procedure	Identify cecum → follow taenia coli to appendix base → divide mesoappendix (stapler/LigaSure) → staple/ligate appendix base → place in retrieval bag → remove
Irrigation	Pelvic irrigation if contamination present; consider cultures
Advantages	Lower wound infection rate, faster recovery, shorter hospital stay, diagnostic capability

Open Appendectomy

Step	Details
Incision	McBurney's (gridiron): oblique muscle-splitting incision at McBurney's point
Alternative	Lanz (transverse) incision for better cosmesis
Preferred when	Perforation with peritonitis; technical failure of laparoscopy; laparoscopy unavailable
Technique	Identify cecum → mesoappendix ligated and divided → appendix base doubly ligated → appendix excised → stump inverted (optional)

Interval Appendectomy

Indication	Timing	Route
Phlegmon or abscess (>5 days) managed nonoperatively	6–8 weeks after resolution	Elective laparoscopic

Percutaneous Drainage (IR-guided)

For periappendiceal abscess amenable to drainage
Performed by interventional radiology
Followed by interval appendectomy at 6–8 weeks
Not appropriate if no safe window, peritonitis, or free perforation

Sabiston Textbook of Surgery | Current Surgical Therapy 14e | Goldman-Cecil Medicine

8. ALGORITHM TO APPROACH APPENDICITIS

PATIENT PRESENTS WITH ACUTE ABDOMINAL PAIN
                    │
                    ▼
        HISTORY & PHYSICAL EXAMINATION
   (Pain migration, anorexia, RLQ tenderness,
    fever, guarding, Rovsing/Psoas/Obturator signs)
                    │
                    ▼
           CALCULATE ALVARADO SCORE
          ┌──────────┼──────────┐
          ▼          ▼          ▼
       SCORE ≤4   SCORE 5–6  SCORE ≥7
    (Unlikely)  (Equivocal) (Probable)
          │          │          │
          ▼          │          ▼
   Consider        IMAGING    LABS + IMAGING
   Alternatives       │       (CBC, CRP, PCT)
   Discharge if  ┌────┴─────┐       │
   well          │          │       │
              ULTRASOUND    CT    CT ABDOMEN
              (children,  (adults,    /PELVIS
              pregnant)    obese)
                    │
            ┌───────┴────────┐
            ▼                ▼
     CT NEGATIVE         CT POSITIVE
   (Appendix normal)   (Appendicitis confirmed)
            │                    │
            ▼                    ▼
     Observe / Admit     DETERMINE TYPE
     Re-evaluate                 │
     Consider alt Dx    ┌────────┴─────────┐
                        ▼                  ▼
               UNCOMPLICATED         COMPLICATED
               (No perforation,    (Perforation / Abscess /
                no gangrene)         Phlegmon / Peritonitis)
                        │                  │
              ┌─────────┴──────┐    ┌──────┴──────┐
              ▼                ▼    ▼              ▼
       APPENDECTOMY    ANTIBIOTICS  DURATION     FREE
       (Laparoscopic,  -ONLY        OF Sx <5d   PERFORATION
       Gold standard)  (selected,   Appendectomy  /PERITONITIS
              │        no fecalith)  ± Drainage       │
              ▼                │         │             ▼
          PREOP ABX       Ertapenem  DURATION Sx ≥5d  EMERGENCY
       + Resuscitation   IV 24–48h   ┌────────────┐   OPEN / LAP
              │         → Oral 7–10d │ IV ABX +   │  APPENDECTOMY
              ▼               │      │Percutaneous│  + LAVAGE
        SURGERY             MONITOR  │  Drainage  │
              │            (Failure? │            │
              ▼             → Surgery)└────────────┘
       POST-OP CARE               │
     (Uncomplicated:              ▼
      same-day/next-day     INTERVAL APPENDECTOMY
      discharge;            at 6–8 WEEKS
      Complicated:
      IV ABX 3–5 days)

Describe causes, ETIOPATHOGENESIS (chart)clinical features and treatment (medical and surgical? management) algorithm chart of chronic intestinal obstruction(

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CHRONIC INTESTINAL OBSTRUCTION — Complete Clinical Reference

1. DEFINITION

Chronic intestinal obstruction refers to a long-standing, persistent or recurrent partial or complete impairment of the normal aboral progression of intestinal contents, lasting weeks to months, resulting from either a fixed mechanical narrowing of the bowel lumen or a chronic failure of intestinal neuromuscular motility (pseudo-obstruction).

It is distinguished from acute obstruction by:

Gradual, insidious onset
Prolonged, often intermittent symptoms
Partial rather than complete obstruction in most mechanical cases
Less immediate risk of strangulation (except in volvulus)

Two major categories exist:

Chronic mechanical intestinal obstruction — fixed anatomical narrowing

Chronic intestinal pseudo-obstruction (CIPO) — functional dysmotility with no obstructing lesion

Sleisenger & Fordtran's GI and Liver Disease | Schwartz's Principles of Surgery

2. CAUSES

A. Mechanical Causes (Intrinsic, Extrinsic, Intraluminal)

Category	Cause	Example
Intraluminal	Tumour / neoplasm	Colorectal carcinoma, carcinoid
	Impacted feces / bezoar	Fecal impaction
	Gallstone (gallstone ileus)	Erodes into bowel via cholecystoenteric fistula
	Foreign body	Ingested material
Intramural	Carcinoma of colon / small bowel	Annular "apple-core" lesion
	Crohn's disease	Stricture formation
	Radiation enteritis / stricture	Post-radiotherapy fibrosis
	Diverticular disease	Stricture of sigmoid colon
	Ischaemic stricture	After mesenteric ischaemia
	Tuberculosis (TB) of bowel	Ileocaecal involvement
	Endometriosis	Cyclic bowel involvement
	Intussusception (chronic)	Lead point tumour
Extrinsic	Adhesions / bands	Post-surgical (most common overall)
	Hernia	Inguinal, femoral, incisional — partially obstructing
	Pelvic/abdominal malignancy	Ovarian, pancreatic, gastric metastases
	Peritoneal carcinomatosis	Multifocal obstruction
	Mesenteric tumour	Desmoid, lymphoma
	Volvulus (subacute)	Sigmoid volvulus

B. Functional / Pseudo-obstruction Causes (CIPO)

Category	Cause
Primary (idiopathic)	Sporadic visceral myopathy or neuropathy (most common in adults)
Familial	Familial visceral myopathy (Types I–III); visceral neuropathy; X-linked (FLNA mutation)
Connective tissue disease	Scleroderma (PSS) — most common secondary cause; SLE; dermatomyositis
Neurological	Parkinson's disease; spinal cord injury; Chagas disease (T. cruzi destroys myenteric plexus)
Endocrine / Metabolic	Hypothyroidism (myxedema); Diabetes mellitus (autonomic neuropathy); hypoparathyroidism (hypocalcaemia)
Muscular dystrophy	Myotonic dystrophy; Duchenne muscular dystrophy
Amyloidosis	Infiltration of enteric nerves + smooth muscle
Paraneoplastic	Small-cell lung cancer → IgG anti-neuronal antibodies → myenteric plexus destruction
Drugs	Opioids, tricyclic antidepressants, phenothiazines, anticholinergics, antipsychotics
Radiation	Radiation enteritis causing dysmotility
Viral	Neurotropic viruses (EBV, CMV, HSV)
Mitochondrial disease	MNGIE syndrome (thymidine phosphorylase deficiency)

Sleisenger & Fordtran | Schwartz's Principles of Surgery | Current Surgical Therapy 14e

3. ETIOPATHOGENESIS (Chart Form)

┌──────────────────────────────────────────────────────────────────────────┐
│                    CHRONIC INTESTINAL OBSTRUCTION                        │
│                                                                          │
│   MECHANICAL CAUSE               FUNCTIONAL CAUSE (CIPO)                 │
│   (fixed narrowing)              (no obstructing lesion)                 │
└──────────┬───────────────────────────────┬──────────────────────────────┘
           │                               │
           ▼                               ▼
┌──────────────────────┐      ┌───────────────────────────────────────┐
│  LUMINAL NARROWING   │      │  NEUROMUSCULAR DYSFUNCTION            │
│  (intraluminal /     │      │  ┌────────────────────────────────┐   │
│   intramural /       │      │  │ NEUROPATHIC:                   │   │
│   extrinsic)         │      │  │ Degeneration / inflammation of │   │
└──────────┬───────────┘      │  │ myenteric (Auerbach) / Meissner│   │
           │                  │  │ plexus → uncoordinated or      │   │
           ▼                  │  │ absent peristaltic contractions│   │
  PARTIAL OCCLUSION           │  └────────────────────────────────┘   │
  of intestinal lumen         │  ┌────────────────────────────────┐   │
           │                  │  │ MYOPATHIC:                     │   │
           ▼                  │  │ Smooth muscle atrophy /        │   │
  PROXIMAL DISTENSION         │  │ fibrosis / replacement by      │   │
  (gas + fluid                │  │ collagen → weak, absent        │   │
   accumulation)              │  │ contractions                   │   │
           │                  │  └────────────────────────────────┘   │
           ▼                  │  ┌────────────────────────────────┐   │
  ┌────────┴──────────┐       │  │ MESENCHYMOPATHY:               │   │
  │ WALL STRETCHING   │       │  │ Deficiency / dysfunction of    │   │
  │ → visceral pain   │       │  │ Interstitial Cells of Cajal    │   │
  │ (colicky /        │       │  │ (ICC — pacemaker cells) →      │   │
  │  intermittent)    │       │  │ lost slow waves / rhythmicity  │   │
  └────────┬──────────┘       │  └────────────────────────────────┘   │
           │                  └───────────────────┬───────────────────┘
           │                                      │
           ▼                                      ▼
  ALTERED MOTILITY                     INEFFECTIVE PERISTALSIS
  (proximal hyper-                     → contents fail to advance
   peristalsis, then
   exhaustion)
           │                                      │
           └─────────────────┬────────────────────┘
                             ▼
              PROGRESSIVE BOWEL DISTENSION
              + STASIS + BACTERIAL OVERGROWTH
                             │
              ┌──────────────┼──────────────────┐
              ▼              ▼                   ▼
        MALABSORPTION   INCREASED          MUCOSAL INJURY
        • Fat, protein   INTRALUMINAL       • Ulceration
        • Vitamins        SECRETIONS        • Translocation of
        • Malnutrition   → Vomiting           bacteria
                                              → Sepsis
              │
              ▼
        RAISED INTRALUMINAL PRESSURE
              │
     ┌────────┴────────────┐
     ▼                     ▼
VENOUS CONGESTION     (In complete obstruction)
→ mucosal ischaemia   ARTERIAL ISCHAEMIA
→ NECROSIS              → PERFORATION
→ PERFORATION           → PERITONITIS

Sleisenger & Fordtran's GI and Liver Disease | Sabiston Textbook of Surgery | Schwartz's Principles of Surgery

4. CLINICAL FEATURES

Symptoms

Symptom	Description
Abdominal pain	Most consistent symptom; colicky, intermittent; may be dull and chronic in CIPO; worsens with eating
Abdominal distension	Progressive; particularly severe during acute-on-chronic episodes
Nausea & vomiting	Intermittent initially; bilious if proximal obstruction; feculent if distal/low obstruction
Constipation / obstipation	Gradual worsening over weeks–months; may alternate with diarrhoea (overflow)
Weight loss & malnutrition	Due to malabsorption, reduced oral intake, bacterial overgrowth; prominent in CIPO
Early satiety / bloating	After meals; relief with fasting
Change in bowel habit	Progressive constipation preceded by weeks–months in LBO

Signs

Sign	Significance
Abdominal distension	Tympanic to percussion
Visible peristalsis	Peristaltic waves visible through abdominal wall — ladder pattern in SBO
High-pitched / tinkling bowel sounds	Mechanical obstruction
Absent / diminished bowel sounds	CIPO / late exhaustion
Succussion splash	Gastric / proximal small bowel obstruction
Palpable mass	Tumour, faecal impaction, hernia
Hernia orifices	Examine groins, umbilicus, scars (irreducible = obstructing)
Cachexia / wasting	Malignancy, chronic malnutrition
Rectal exam	Empty rectum in obstruction; impacted faeces; blood — malignancy
Signs of malignancy	Sister Mary Joseph nodule, Virchow's node (left), hepatomegaly

Features Specific to CIPO

Recurrent acute episodes superimposed on chronic dysmotility
Symptoms often fluctuate — better with fasting, worse after meals
No mechanical cause found on imaging despite clinical picture of obstruction
Small bowel dilatation on imaging with no transition point
Prominent nutritional failure and malabsorption

Sleisenger & Fordtran | Schwartz's Principles of Surgery | Harrison's Principles of Internal Medicine 22e

5. DIAGNOSIS / INVESTIGATIONS

Investigation	Finding / Purpose
Plain AXR (erect + supine)	Dilated loops of bowel; air-fluid levels; absent distal gas; "string of beads" (SBO); colonic dilatation (LBO/CIPO); caecal diameter >12–14 cm = emergency
CT Abdomen/Pelvis (IV ± oral contrast)	Gold standard; identifies site, cause, and complications; detects transition point, mass, volvulus, ischaemia (wall non-enhancement), abscess, peritoneal disease
CT Enteroclysis	Optimal for low-grade partial SBO; water-soluble contrast via naso-enteric tube distends loops for accurate assessment
Contrast studies (water-soluble)	Gastrografin enema for LBO; "apple-core" = carcinoma; delineates point of obstruction
Colonoscopy / flexible sigmoidoscopy	Diagnose and stent colonic tumours; decompress volvulus
Small bowel follow-through (SBFT) / MRI enterography	Crohn's disease strictures; radiation strictures; chronic partial SBO
Intestinal manometry	Key in CIPO: differentiates mechanical from functional obstruction; identifies neuropathic vs. myopathic pattern
Full-thickness biopsy (laparoscopic)	In CIPO: identifies ICC deficiency, myopathy, neuropathy — seldom reveals treatable cause
Bloods	FBC (anaemia, leukocytosis); CRP/ESR; U&E (dehydration, electrolyte disturbances); LFTs; serum albumin (nutritional status); TFTs (hypothyroidism); Ca²⁺ (hypoparathyroidism); glucose (DM)
Tumour markers	CEA, CA-125, CA 19-9 — if malignancy suspected
Urine / serum	Thymidine phosphorylase (MNGIE); lactate, CPK (mitochondrial disease)
Autoimmune screen	ANA, anti-Scl-70 (scleroderma); anti-Hu (paraneoplastic neuropathy)

Plain X-ray showing distended small bowel loops with air-fluid levels in intestinal obstruction

Plain abdominal X-ray: supine and erect views showing dilated small bowel loops with air-fluid levels — Sleisenger & Fordtran's GI Disease

6. MANAGEMENT (Table Form)

A. MEDICAL MANAGEMENT

Intervention	Indication / Details
IV Fluid Resuscitation	Correct dehydration; Hartmann's / Normal saline; monitor urine output
Nasogastric (NG) tube decompression	Decompress proximal bowel; remove accumulated gas/fluid; relieve vomiting
Electrolyte correction	K⁺, Na⁺, Cl⁻ — especially with vomiting; hypochloraemic hypokalaemic alkalosis (proximal obstruction)
NPO / bowel rest	Reduce luminal contents and distension
Nutritional support	Enteral (jejunal tube if feasible) preferred; Total parenteral nutrition (TPN) if severe CIPO or prolonged obstruction; high-calorie, high-protein liquid diet in partial obstruction
Antibiotics	Broad-spectrum (e.g., piperacillin-tazobactam, metronidazole) for bacterial translocation / sepsis; cover anaerobes + gram-negatives
Analgesia	Opioids for acute pain (avoid prolonged use — worsen motility); NSAIDs / antispasmodics for colicky pain
Antiemetics	Metoclopramide (partial/functional only), ondansetron, haloperidol; avoid metoclopramide in complete obstruction
Octreotide	Inhibits GI secretion → reduces distension, vomiting, colicky pain; key in malignant / CIPO obstruction; 100–300 mcg SC/IV TDS
Steroids (dexamethasone)	Anti-inflammatory; reduce peritoneal oedema; useful in malignant obstruction and CIPO (acute episodes)
Prokinetics (CIPO)	Pyridostigmine (acetylcholinesterase inhibitor — increases ACh at neuromuscular junction → promotes contractions); Neostigmine (IV — acute episodes); Prucalopride (5-HT₄ agonist); Erythromycin (motilin agonist)
Treat underlying cause	Levothyroxine (hypothyroidism); calcium (hypoparathyroidism); stop offending drugs (opioids, TCAs); treat Chagas disease, Parkinson's disease; immunosuppression for connective tissue disease
Endoscopic stenting	Self-expanding metal stents (SEMS): for colonic malignancy — bridge to surgery OR palliation; also gastroduodenal, jejunal; avoids emergency surgery
Colonoscopic decompression	Sigmoid/caecal volvulus — effective in up to 85% of sigmoid volvulus cases; recurrence is high — follow with elective surgery
Venting gastrostomy / gastrostomy tube	Palliative; avoids prolonged NG tube; allows oral intake for pleasure in inoperable malignant obstruction
Water-soluble contrast (Gastrografin)	Therapeutic in adhesion-related partial SBO: draws fluid into lumen, promotes resolution; also diagnostic

B. SURGICAL MANAGEMENT

Procedure	Indication	Notes
Adhesiolysis	Adhesive chronic/partial SBO	Laparoscopic preferred; open if dense/multiple adhesions
Bowel resection + anastomosis	Malignant stricture, Crohn's stricture, radiation stricture, ischaemic stricture	Primary anastomosis if bowel viable and patient stable
Strictureplasty	Crohn's disease — multiple strictures, preserve bowel length	Heineke-Mikulicz / Finney technique
Colostomy / Ileostomy	Decompressing stoma for LBO; palliation	Hartmann's procedure for perforated/obstructing sigmoid carcinoma
Right hemicolectomy	Right-sided colonic carcinoma	Includes terminal ileum; ileo-colic anastomosis
Left hemicolectomy / sigmoid resection	Left colonic / sigmoid carcinoma	Primary anastomosis or staged (Hartmann's)
Hernia repair + bowel resection	Obstructing hernia	Reduce bowel; resect if non-viable; mesh repair after contamination controlled
Volvulus reduction + resection	Sigmoid volvulus (after failed endoscopy); caecal volvulus	Sigmoid: resection + primary anastomosis or Hartmann's; Caecal: right hemicolectomy
Bypass surgery	Unresectable tumour; dense adhesions	Entero-enterostomy or gastrojejunostomy
Percutaneous endoscopic / IR gastrostomy	Malignant obstruction — palliation; CIPO — vent	Relieves nausea/vomiting; allows oral intake
Intestinal transplantation	End-stage CIPO with intestinal failure requiring long-term TPN	Specialist centre; last resort
Peritoneal carcinomatosis: cytoreductive surgery (CRS) + HIPEC	Selected patients with peritoneal malignancy	High morbidity; strict patient selection

Harrison's Principles 22e | Sleisenger & Fordtran | Schwartz's Principles of Surgery | Current Surgical Therapy 14e

7. ALGORITHM TO APPROACH CHRONIC INTESTINAL OBSTRUCTION

PATIENT: Chronic / Progressive Abdominal Pain, Distension,
         Vomiting, Constipation (weeks–months duration)
                          │
                          ▼
            HISTORY & PHYSICAL EXAMINATION
     (Duration, bowel habit change, weight loss, prior
      surgery, malignancy, hernia, medications, family Hx)
                          │
                          ▼
            INITIAL INVESTIGATIONS
     (FBC, U&E, CRP, LFTs, albumin, TFTs, Ca²⁺,
      tumour markers; erect + supine AXR)
                          │
                          ▼
           DILATED BOWEL ON AXR?
          ┌──────────────────────┐
          ▼                      ▼
         YES                     NO
  CT Abdomen/Pelvis    Consider other diagnosis
  with IV contrast     (IBS, gastroparesis,
          │             constipation, etc.)
          ▼
  ─────────────────────────────────────────
  IDENTIFY: MECHANICAL vs FUNCTIONAL
  ─────────────────────────────────────────
          │
   ┌──────┴────────────────────────────────┐
   ▼                                       ▼
MECHANICAL OBSTRUCTION            FUNCTIONAL (CIPO)
(transition point, mass,          (dilated bowel, no
 stricture, hernia on CT)          transition point)
   │                                       │
   ▼                                       ▼
DETERMINE SITE                    RULE OUT MECHANICAL
   │                              (CT enteroclysis /
   ├── SMALL BOWEL (SBO)           water-soluble contrast)
   │                                       │
   └── LARGE BOWEL (LBO)           INTESTINAL MANOMETRY
          │                        FULL-THICKNESS BIOPSY
          ▼                        SEARCH FOR SECONDARY CAUSE
DETERMINE CAUSE                    (TFTs, ANA, anti-Hu,
   │                                glucose, drugs review)
   ├── ADHESIONS / BANDS                   │
   ├── MALIGNANCY                          ▼
   ├── HERNIA                     TREAT UNDERLYING CAUSE
   ├── CROHN'S STRICTURE          + SUPPORTIVE MANAGEMENT
   ├── RADIATION STRICTURE        (See Medical Mx above)
   ├── VOLVULUS                            │
   └── OTHER                              ▼
          │                      NUTRITIONAL SUPPORT
          ▼                      (oral → enteral → TPN)
   IS THERE ISCHAEMIA / PERFORATION?       │
          │                               ▼
    ┌─────┴──────┐              PROKINETICS (Pyridostigmine,
    ▼            ▼               Prucalopride, Neostigmine,
   YES          NO               Octreotide for secretions)
    │            │                         │
    ▼            ▼               ┌─────────┴─────────┐
EMERGENCY    COMPLETE vs         ▼                   ▼
SURGERY      PARTIAL?          IMPROVES          FAILS TO IMPROVE
(IV ABx,          │           (Continue          (Endoscopic /
 resuscitate,     │            medical Mx)        Surgical options)
 urgent OR)       │
          ┌───────┴───────┐
          ▼               ▼
       COMPLETE         PARTIAL
       │                 │
       ▼                 ▼
  URGENT               TRIAL OF
  SURGICAL             CONSERVATIVE Mx
  ASSESSMENT           • IV fluids / NG tube
       │               • Water-soluble contrast
       ▼               • 24–48 h observation
  RESUSCITATE          • Repeat CT at 48h if
  IV ABx, NG             no improvement
  Correct               │
  electrolytes          ▼
       │         RESOLVES?     FAILS?
       ▼           │             │
   SURGERY         ▼             ▼
  ┌────────┐   Discharge      SURGERY
  │ BY     │   + elective   ┌────────────────────────────────────┐
  │ CAUSE  │   workup       │ BY CAUSE:                          │
  └────────┘                │ • Adhesiolysis (laparoscopic/open)  │
  • Adhesiolysis            │ • Bowel resection ± anastomosis     │
  • Resection ± anastomosis │ • Strictureplasty (Crohn's)        │
  • Hernia repair           │ • Colostomy / Hartmann's           │
  • Decompressing stoma     │ • Hernia repair                    │
  • Bypass                  │ • Volvulus reduction/resection     │
  • Volvulus Rx             │ • Stenting (SEMS) — malignancy     │
  • SEMS for malignancy     │ • Bypass / stoma (palliation)      │
  (bridge to surgery or     └────────────────────────────────────┘
   palliation)

Sources: Sleisenger & Fordtran's Gastrointestinal and Liver Disease | Schwartz's Principles of Surgery 11e | Current Surgical Therapy 14e | Mulholland & Greenfield's Surgery 7e | Harrison's Principles of Internal Medicine 22e

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