Gallstone Disease

Gallstones are prevalent, particularly in 'Female, Forty, Fat, Fertile' individuals. Most are asymptomatic. Symptomatic presentations are crucial for finals:
1. **Biliary Colic:** Transient cystic duct obstruction, causing episodic, post-prandial RUQ pain.
2. **Acute Cholecystitis:** Prolonged obstruction leading to gallbladder inflammation/infection, presenting with constant RUQ pain and fever.
3. **Choledocholithiasis:** Stones in the common bile duct (CBD), causing obstructive jaundice.
4. **Ascending Cholangitis:** A severe, life-threatening infection of the biliary tree (Charcot's Triad: fever, jaundice, RUQ pain).
5. **Gallstone Pancreatitis:** Pancreatic duct obstruction by a stone.

**Diagnosis:** Transabdominal ultrasound is first-line. If CBD stones are suspected (e.g., abnormal LFTs, dilated CBD on US), MRCP is the next step. Management often involves laparoscopic cholecystectomy for symptomatic disease, with urgent ERCP for cholangitis or severe choledocholithiasis.

Gallstones form due to an imbalance in bile composition. **Cholesterol stones** (most common in the UK) result from cholesterol supersaturation, often linked to obesity, rapid weight loss, or metabolic syndrome. **Pigment stones** (black) are associated with haemolysis (excess unconjugated bilirubin), while **brown pigment stones** are linked to biliary stasis and infection. Stasis (e.g., pregnancy) allows stone growth. Acute cholecystitis occurs when a stone obstructs the cystic duct, leading to chemical irritation, ischaemia, and secondary bacterial infection (commonly *E. coli*, *Klebsiella*, *Enterococcus*).

**Biliary Colic:** Classic RUQ/epigastric pain, radiating to the right shoulder/scapula, lasting minutes to hours, often post-fatty meal. No fever or leukocytosis.
**Acute Cholecystitis:** Persistent RUQ pain (>6 hours), fever, nausea, vomiting, positive Murphy's sign. Look for leukocytosis and raised CRP.
**Obstructive Jaundice:** Pale stools, dark urine, pruritus, and jaundice indicate CBD obstruction. Check LFTs (raised bilirubin, ALP, GGT).
**Ascending Cholangitis:** Charcot's Triad (fever, jaundice, RUQ pain). If hypotension and altered mental status are present, it's Reynolds' Pentad – indicating septic shock and requiring immediate resuscitation and intervention.
**Gallstone Ileus:** A rare mechanical small bowel obstruction where a large gallstone erodes into the duodenum, then obstructs the terminal ileum. Look for Rigler's Triad on AXR: pneumobilia, small bowel obstruction, and an ectopic gallstone.

**Bloods:**
- **FBC:** Leukocytosis suggests inflammation/infection (e.g., cholecystitis, cholangitis).
- **LFTs:** Elevated bilirubin, ALP, and GGT strongly suggest CBD obstruction. ALT/AST may be raised in acute cholecystitis or pancreatitis.
- **Amylase/Lipase:** Essential to rule out gallstone pancreatitis.
- **CRP:** Elevated in inflammatory conditions.

**Imaging:**
- **Transabdominal Ultrasound (USS):** First-line. Highly sensitive for gallstones (hyperechoic foci with posterior shadowing), gallbladder wall thickening (>4mm), pericholecystic fluid, and CBD dilatation (>6mm is suspicious).
- **MRCP (Magnetic Resonance Cholangiopancreatography):** Non-invasive, diagnostic. Used when CBD stones are suspected (e.g., abnormal LFTs, dilated CBD on USS) but not clearly seen. Excellent for visualising the biliary and pancreatic ducts.
- **CT Abdomen:** Less sensitive for gallstones than USS, but useful in complicated cases (e.g., perforation, abscess, or to rule out other causes of abdominal pain).
- **ERCP (Endoscopic Retrograde Cholangiopancreatography):** Both diagnostic and therapeutic. Used when there is high suspicion or confirmed CBD stones requiring removal. Visualises ducts directly and allows for sphincterotomy and stone extraction.

**Biliary Colic:**
- **Analgesia:** NSAIDs (e.g., diclofenac) are often more effective than opioids for biliary pain.
- **Definitive:** Elective laparoscopic cholecystectomy.

**Acute Cholecystitis:**
- **Initial:** IV fluids, IV antibiotics (e.g., co-amoxiclav, piperacillin/tazobactam).
- **Definitive:** Laparoscopic cholecystectomy, ideally within 72 hours of symptom onset (early cholecystectomy reduces complications and hospital stay).

**Choledocholithiasis (CBD stones):**
- **Initial:** ERCP with sphincterotomy and stone extraction.
- **Follow-up:** Laparoscopic cholecystectomy (usually within 2-6 weeks) to prevent recurrence.

**Ascending Cholangitis:**
- **Emergency!** ABCDE approach, IV fluids, broad-spectrum IV antibiotics (e.g., meropenem + metronidazole).
- **Urgent Biliary Drainage:** ERCP is the preferred method for decompression (sphincterotomy and stent insertion/stone removal). Percutaneous transhepatic cholangiography (PTC) drainage is an alternative if ERCP fails or is unavailable.

**Gallstone Pancreatitis:**
- **Initial:** Supportive care (IV fluids, analgesia, nutritional support).
- **Definitive:** ERCP if there's ongoing biliary obstruction (e.g., rising LFTs, cholangitis). Laparoscopic cholecystectomy once pancreatitis has settled to prevent recurrence.