Abdominal pain accounts for ~5% of all GP consultations; the challenge is that serious diagnoses are uncommon but catastrophic if missed. AAA rupture carries >80% mortality without intervention. Ectopic pregnancy is the leading cause of maternal mortality in the first trimester in the UK. Mesenteric ischaemia has 60–80% mortality — the classic teaching "pain out of proportion to signs" is the key diagnostic cue. Ovarian torsion requires detorsion within 4–6h to preserve ovarian function. DKA with SGLT2i inhibitors can present with euglycaemic DKA — blood glucose may be normal despite life-threatening ketosis.

A systematic pain history using SOCRATES correctly identifies the diagnosis in 60–70% of abdominal pain presentations before examination. The migration of pain from periumbilical to RIF is present in 60% of confirmed appendicitis cases. Colicky pain with complete absence in between strongly suggests hollow viscus obstruction or colic rather than inflammation. Understanding onset speed (seconds vs hours) is the single most important discriminator between surgical emergency and subacute disease.

Acuity classification drives the time-critical decision: Can this patient safely wait for primary care workup, or do they need hospital today? Pancreatitis severity (GLASGOW score in hospital) determines HDU admission need. Mild diverticulitis (no systemic upset, able to eat) can be managed in primary care with antibiotics; moderate/severe requires admission. All reproductive-age women presenting with lower abdominal pain must have a pregnancy test — a missed ectopic pregnancy is a never event.

Murphy's sign has 97% specificity for acute cholecystitis when positive. Involuntary guarding (rigidity) is the single most important sign of peritonitis — it is not suppressible by the patient and indicates surgical emergency. Carnett's test differentiates visceral from abdominal wall pain with 78–88% accuracy — positive Carnett's (worsens on raising head) suggests abdominal wall haematoma, hernia, or nerve entrapment, avoiding unnecessary investigations. A missed irreducible femoral hernia (most common in elderly women) causing obstruction is a preventable surgical emergency.

Amylase >3× ULN has 85% sensitivity for pancreatitis but lipase remains elevated for 3–5 days vs amylase's 1–2 days, making it more useful in delayed presentations. Urine hCG must be performed in all reproductive-age women — a negative result does not exclude ectopic in the very early stages (beta-hCG may be below urinary detection threshold; serum beta-hCG is more sensitive). Faecal calprotectin has NICE endorsement for distinguishing IBD from IBS — levels >200 µg/g have 93% sensitivity for IBD, making it a powerful primary care investigation before referral.

The most dangerous error in abdominal pain is delayed referral. The classic Alvarado score for appendicitis (score ≥7 → surgery) is not validated for primary care use — clinical gestalt and examination findings should drive the referral decision. Cholecystitis with fever indicates bacterial superinfection and requires IV antibiotics and potential same-day cholecystectomy. NICE NG12's 2WW criteria were developed from UK cancer audit data — adherence reduces time-to-treatment and improves survival outcomes. A threshold of uncertainty = refer: primary care cannot rule out surgical emergencies.

Analgesia does not mask diagnosis — multiple RCTs demonstrate opioids and NSAIDs in the acute abdomen do not affect diagnostic accuracy and improve patient experience and cooperation with examination. Withholding analgesia is harmful and unethical. H. pylori eradication: cure rate with triple therapy ~70–85%; reduces ulcer recurrence from 80% to <5% at 1 year. NSAIDs for biliary colic: Cochrane review confirms superiority over opioids for biliary colic with fewer side effects. Tamsulosin for renal colic: MET-STONE trial — increases stone passage rate by 26% for stones 5–10mm, reduces need for surgical intervention.

Low-FODMAP diet (Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols) reduces IBS symptoms in 75% of patients in multiple RCTs — it is as effective as pharmacological treatment and should be first-line for IBS managed in primary care. CBT for IBS has NNT ~3–4 for significant symptom improvement. Increasing fluid intake reduces renal stone recurrence by 60% — it is the single most cost-effective intervention in urolithiasis. Smoking cessation reduces PUD healing time from 8 weeks to 4 weeks and reduces recurrence by 50%.

Diverticulitis failing to improve on antibiotics at 72h carries a 15% risk of perforation without escalation. H. pylori eradication must be confirmed with a stool antigen test — treatment failure rates are ~15–30%, and undetected failure leads to ongoing ulceration and cancer risk. IBS patients benefit from structured review: patient satisfaction and symptom control improve by 40% in practices that offer structured follow-up vs PRN appointments. Safety-netting must be documented — this is an RCGP SCA clinical competency domain and medicolegally critical.