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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Acute abdominal pain and the surgical abdomen

Gastroenterology and hepatology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull
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Escalate

Shock, generalised peritonism, a pulsatile abdominal mass, pain out of proportion to examination, rigid distension with vomiting, incarcerated hernia, gastrointestinal bleeding with instability, or abdominal pain in pregnancy with collapse demands immediate ABCDE care and senior surgical, vascular or obstetric involvement. Imaging must not delay transfer or treatment when rupture or another immediately lethal diagnosis is clinically compelling.

Synopsis

Recognise physiological danger and time-critical surgical causes of acute abdominal pain, resuscitate in parallel with diagnosis, and choose examination and imaging that lead to a definitive disposition.

  • Decide whether the patient is unstable before refining the pain history: record respiratory rate, oxygen saturation, pulse, blood pressure, temperature, consciousness, perfusion and urine output.
  • Treat pain and nausea early while repeating examination; analgesia supports humane care and does not prevent competent recognition of peritonism or deterioration.
  • Pain beginning diffusely then localising can reflect evolving parietal irritation, while abrupt maximal-at-onset pain raises vascular rupture, ischaemia, perforation, torsion or renal colic.
  • Always ask about previous abdominal operations, hernias, anticoagulants, NSAIDs, alcohol, gallstones, vascular disease, pregnancy possibility and relevant gynaecological or testicular symptoms.
  • Peritonism is a syndrome of involuntary guarding, percussion or cough tenderness and rigidity; an older, immunosuppressed or steroid-treated patient may have dangerous disease with muted signs.
  • A normal lactate does not exclude early mesenteric ischaemia, and a raised lactate is not specific; clinical probability determines urgent CT angiography and surgical discussion.
  • Use ultrasound for focused biliary, pelvic and aortic questions, contrast CT for many undifferentiated acute abdomens, and arterial-phase imaging when vascular pathology is suspected.
  • Keep the patient fasting when surgery or procedural sedation is plausible, establish venous access, correct fluid and electrolyte deficits, and give antimicrobial treatment promptly when sepsis or perforation is suspected.

Key red flags

Ruptured abdominal aortic aneurysm

Sudden abdominal, flank or back pain with syncope, shock or a known aneurysm should trigger immediate vascular consideration. The classic pulsatile mass may be absent, and transient response to fluid does not remove rupture risk.

Mesenteric ischaemia

Severe pain disproportionate to early abdominal findings, atrial fibrillation, atherosclerosis, low-flow state or postprandial chronic symptoms raises bowel ischaemia. Peritonism indicates advanced injury; normal early lactate cannot safely exclude it.

Perforated viscus

Abrupt severe pain, generalised guarding or rigidity, sepsis and free intraperitoneal gas support perforation. Absence of visible free gas on plain radiography does not exclude a contained or early perforation.

Mechanical obstruction and strangulation

Colicky pain, vomiting, distension and obstipation suggest obstruction; constant worsening pain, focal tenderness, fever, tachycardia, acidosis or a closed-loop configuration raises compromised blood supply and demands urgent surgery.

Investigation priorities

01
Serial observations and NEWS2First step

Detect shock, sepsis, respiratory compromise and trajectory while diagnostic work continues.

Management branches

Unstable abdomenResuscitate while summoning definitive care

Abdominal pain accompanies shock, peritonism or another immediate physiological threat.

  1. Begin ABCDE, obtain large-bore venous access, send urgent bloods and group-and-save or crossmatch, monitor urine output and provide appropriate oxygen and warmed fluid or blood support.
  2. Call the relevant senior surgeon immediately and involve vascular, gynaecology, urology, anaesthesia or critical care according to the leading threat.
  3. Give analgesia and antiemetic treatment, start locally recommended antimicrobials when sepsis or perforation is suspected, and keep the patient fasting.
  4. Use only imaging that changes immediate definitive management; do not transfer an unstable patient to an unsuitable scanner without senior planning and resuscitation capability.
Stable severe painLocalise and discriminate

The patient is physiologically stable but pain is severe, focal or unexplained.

  1. Take a time-ordered history including operations, vascular, drug, alcohol, pregnancy and extra-abdominal factors, then perform targeted abdominal, groin and cardiorespiratory examination.
  2. Obtain focused bloods, urinalysis and pregnancy testing, provide analgesia, fasting and fluid correction, then repeat examination for evolving localisation.

Key medicines

Titrated opioid or non-opioid analgesiaGive incremental analgesia using the current local acute-pain and BNF regimen, adjusted for frailty, kidney function, respiratory risk and previous exposure.Monitor sedation, respiration and blood pressure; avoid NSAIDs when bleeding, kidney injury or perforation is plausible, and do not let symptom improvement cancel reassessment.
Empirical intravenous antimicrobialsUse the locally approved severe intra-abdominal infection regimen promptly after appropriate cultures, with allergy, renal function and likely source considered.Antibiotics cannot replace drainage or surgery. Record indication and review against cultures, imaging and source control; local resistance and stewardship policy determine selection and duration.
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Sources and review status7 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE NG104 pancreatitisRecognition, aetiological assessment, nutrition and multidisciplinary management of acute pancreatitis.
  • NICE NG147 diverticular diseaseSame-day assessment, laboratory testing and contrast CT for suspected complicated acute diverticulitis.
  • NICE CG188 gallstone diseaseUltrasound, liver tests and biliary investigation pathways.
  • NICE NG156 abdominal aortic aneurysmEmergency recognition, transfer and imaging for suspected symptomatic or ruptured abdominal aortic aneurysm.
  • NICE NG253 suspected sepsisCurrent adult sepsis recognition, escalation and antimicrobial principles.
  • NHS Highland acute mesenteric ischaemia guidelineUK NHS guidance on disproportionate pain, lactate limitations, urgent arterial CT and surgical escalation.
  • Royal College of Surgeons Annals review of adhesional small-bowel obstructionUK surgical review stating that peritonitis, bowel strangulation or ischaemia requires emergency surgery rather than a conservative obstruction pathway.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. ·

  • Choose ultrasound for a defined biliary or pelvic question, contrast CT for broad acute pathology, or CT angiography when ischaemia or vascular catastrophe remains plausible.
  • Discuss the imaging request and patient directly with surgery or radiology when delay, contrast risk or uncertain protocol could change outcome.
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    Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom