Acute Abdomen and GI Surgical Emergencies

In depth

The one-page summary above is what the PDF prints. These sections go further.

Reading the acute abdomen

Peritoneal signs are involuntary guarding, rigidity and rebound tenderness; a patient lying very still with severe pain and a silent abdomen suggests peritonitis. Shock, severe pain, peritonitis and distension are the red flags. Merck lists ruptured aortic aneurysm, perforated viscus, mesenteric ischemia and ruptured ectopic pregnancy as needing surgery at once, with obstruction, appendicitis and severe pancreatitis close behind. Imaging must not delay surgery when the findings are already definitive.

High-risk groups are the very old, the very young and anyone on corticosteroids or other immunosuppressants. These drugs blunt the inflammatory response, so a perforation can cause less pain, less tenderness and a smaller WBC rise than expected; a new tachycardia may be the main clue. Merck states that moderate IV analgesia (fentanyl 50-100 mcg or morphine 4-6 mg) does not mask peritoneal signs and often makes the examination easier.

Imaging (IDSA 2024): CT is the suggested first test for suspected appendicitis and abscess in non-pregnant adults; ultrasound first for children and pregnant patients with suspected appendicitis and for adults with suspected cholecystitis or cholangitis. Intra-abdominal cultures are suggested when source control is done for a complicated infection, not routinely for uncomplicated appendicitis. Blood cultures are suggested with fever plus hypotension, tachypnea or delirium, or concern for resistant organisms.

Small bowel obstruction in depth

Adhesions, hernias and tumors cause most mechanical obstruction. Adhesions follow abdominal surgery; a hernia is usually found on examination; so a small bowel obstruction with neither prior surgery nor a hernia is often a tumor (Merck). Simple obstruction gives colicky pain, vomiting and high-pitched bowel sounds over a nontender abdomen. Strangulation (nearly a quarter of small bowel obstructions, usually hernia, volvulus or intussusception) blocks venous outflow first, then arterial inflow, and can reach gangrene in about 6 hours: steady severe pain (versus cramps), then tenderness and a silent abdomen, with shock and low urine output as serious signs. A raised WBC and acidosis suggest strangulation has occurred but may be absent, so normal values do not exclude it; only laparotomy confirms it.

On CT, dilated proximal bowel with collapsed distal bowel strongly suggests obstruction. Gas in the bowel wall (pneumatosis intestinalis) means gangrene. The WSES Bologna 2017 update prefers nonoperative care for adhesive obstruction unless there is peritonitis, strangulation or ischemia, considers a 72-hour trial safe, and uses water-soluble oral contrast: contrast reaching the colon on a film at 24 hours predicts resolution, and failure to reach it predicts failure. CT signs that call for surgery without delay include a closed loop, ischemia and free fluid. Merck: about 85% of partial small bowel obstructions resolve without surgery; complete obstruction is usually operated on early, after 2 to 3 hours of fluid resuscitation in a very dry patient. A third-generation cephalosporin is given before exploration when ischemia is suspected.

Large bowel obstruction is slower: constipation, then obstipation and distension, with late vomiting and few fluid shifts. The cecum is the usual perforation site, with high risk at 13 cm or more. Sigmoid volvulus (a long redundant loop twisting on its mesentery) can often be untwisted with a sigmoidoscope or long rectal tube when there is no gangrene; resection is then done a few days later because recurrence is almost certain without it. Cecal volvulus is treated by resection.

NG decompression in depth

A nasogastric tube decompresses the stomach in obstruction and ileus. Open RN advises low intermittent suction, starting at 40-60 mm Hg and not above 80 mm Hg, watching gastric contents flow into the tubing and recording the color, odor, consistency and amount in the canister. Its sample notes show a 30 mL irrigation flush and flag resistance on irrigation as an unexpected finding to report. When symptoms return with little drainage, the usual causes are a kinked, clogged or displaced tube or failed suction, so the usual nursing teaching is to check those before giving an antiemetic or replacing the tube (classic teaching; the Open RN pages do not list kinks).

Losses from vomiting and NG suction deplete sodium and potassium, and potassium matters doubly because a low level worsens ileus. Merck gives 0.9% saline or lactated Ringer's for resuscitation and a urinary catheter to follow output.

Ileus and Ogilvie syndrome in depth

After abdominal surgery the small bowel recovers within hours, the stomach in about 24 hours and the colon in 48-72 hours or more (Merck). Opioids, anticholinergics, low potassium, inflammation and retroperitoneal blood prolong ileus. Ileus causes distension and vague discomfort rather than colicky pain, with a quiet abdomen. Care is NPO, nasogastric suction if vomiting, IV fluids and electrolytes with potassium kept above 4 mEq/L, few sedatives and avoidance of opioids and anticholinergics; walking and opioid-sparing analgesia are the nursing measures (RN Basics: Perioperative Care). Ileus lasting more than a week probably has a mechanical cause.

Acute colonic pseudo-obstruction (Ogilvie syndrome) is massive colonic dilation without a blockage, mostly in older patients after surgery, orthopedic procedures, trauma or serious illness. Maloney and Vargas (2005): perforation occurs in 1-3% and is rare below a 12 cm cecum but reaches 23% above 14 cm; mortality is 50-71% after perforation vs about 8% without. Conservative care for 48-72 hours (bowel rest, NG and rectal tubes, electrolytes, stopping opioids, treating infection) succeeds in 83-96%. Neostigmine was given as 2 mg IV over 3-5 minutes in the randomized trial (17 of 18 treated patients responded; most series used 2.5 mg) and works in most patients; trials excluded heart rate under 60, low blood pressure and signs of perforation, and it is contraindicated in mechanical bowel or urinary obstruction. Give it with continuous cardiac monitoring and atropine at hand. Colonoscopic decompression is the next step; surgery is for perforation or ischemia.

Mesenteric ischemia in depth

The gut receives 20-25% of cardiac output, and necrosis can begin about 6 hours after onset. Early on the abdomen is soft with little tenderness despite severe pain; guarding, rigidity, absent bowel sounds, bloody stool and shock come with infarction. WSES 2022: severe pain out of proportion to the examination is mesenteric ischemia until proven otherwise; no laboratory test confirms or excludes it, though lactate above 2 mmol/L was linked to irreversible ischemia; plain films are not recommended. CT angiography is done immediately whenever it is suspected, despite acute kidney injury, and WSES notes that each 6-hour delay roughly doubles mortality. Untreated mortality is about 50%. The cause shares in the table are Merck's; WSES quotes embolism at about 50% in one section and about 25% in another, so no single split is settled.

Initial care: fluids, electrolytes, NG decompression, immediate broad-spectrum antibiotics and full-dose unfractionated heparin. Vasoconstrictors reduce mesenteric flow; if support is needed, WSES prefers dobutamine, low-dose dopamine or milrinone. Arterial occlusion is opened endovascularly where possible, revascularization comes before resection of dead bowel, and a planned second look at 24-48 hours decides what else is viable. Venous thrombosis is treated with a heparin infusion and surgery only for peritonitis. Nonocclusive ischemia follows low flow and vasopressors (for example after cardiac surgery): restore cardiac output, cut vasoconstrictors, and consider intra-arterial papaverine.

Ischemic colitis is a milder, slower drop in colonic flow, mostly in adults over 60 and after aortic aneurysm repair or a low-flow state: left lower quadrant pain followed by rectal bleeding, diagnosed by CT or colonoscopy. Most cases settle with fluids, bowel rest and antibiotics; surgery is needed when it complicates a vascular procedure or the necrosis is full thickness (Merck).

Perforation in depth

Upper GI perforation starts suddenly with severe generalized pain, tenderness, peritoneal signs and sometimes shoulder pain; lower perforations evolve more gradually. Free air under the diaphragm appears in 50-75% of cases (Merck; WSES quotes 30-85%) and becomes more common with time; a lateral chest film is more sensitive than a frontal one; CT is next if films are negative, and up to 12% of perforations have a normal CT (WSES 2020). Barium is never used. Treatment: fluids, broad-spectrum antibiotics, often an NG tube, a urinary catheter and surgery as soon as possible, because peritonitis mortality rises with delay.

Perforated peptic ulcer (WSES 2020): operate promptly; laparoscopic repair in stable patients, open surgery if unstable; primary closure for perforations under 2 cm, with an omental patch not routinely required; antibiotics for 3-5 days; nonoperative care only in very selected sealed leaks. Weighted 30-day mortality is about 23.5%, and low albumin is the strongest single predictor.

Appendicitis: epigastric or periumbilical pain, then anorexia, nausea or vomiting, then right lower quadrant pain over McBurney point, worse with cough and movement. Rovsing (RLQ pain when the left side is pressed), psoas and obturator signs help. Fever is usually low grade (37.7-38.3 °C) and WBC typically 12,000-15,000, but a normal count does not exclude it; older adults, pregnant patients and young children present atypically. Merck: a third-generation cephalosporin before appendectomy, continued 4 days after perforation; a 15% negative appendectomy rate is accepted because delay raises mortality; mortality with early surgery is under 1%. An abscess is drained first and the appendix removed later.

Colonoscopy perforation (WSES 2017): more likely after therapeutic procedures; the sigmoid is the usual site (53-65%); about 45-60% are seen during the procedure and about 91-92% of patients have symptoms within 48 hours (pain, guarding, tachycardia, fever). CT is more sensitive than plain films. Defects under 1 cm found during the procedure or within 4 hours can be clipped; stable patients with localized pain may be treated with bowel rest, IV antibiotics and serial examinations; peritonitis or deterioration means surgery. Mortality is 5-25%. Bleeding after polypectomy is managed as lower GI bleeding (ICU Basics: GI Bleeding, Liver Failure and Pancreatitis).

Esophageal rupture: most are caused by endoscopy; Boerhaave syndrome is the transmural tear after forceful vomiting, usually in the left distal esophagus, unlike a Mallory-Weiss mucosal tear that bleeds. The classic Mackler triad (vomiting, chest pain, subcutaneous emphysema) is often incomplete. Films may show mediastinal air, a left effusion or widening; CT with water-soluble oral contrast is the test of choice. Broad-spectrum antibiotics and fluid resuscitation precede surgical repair and drainage; stents, clips or vacuum therapy suit some cases. Mortality is 19-28% even with treatment (Merck); the StatPearls abstract gives up to 60% with intervention and nearly 100% without.

Source control and antibiotics

WSES and partner societies (2021): identify and control the source as soon as possible, and start broad empiric antibiotics as soon as possible in patients with organ dysfunction or septic shock. After adequate source control, about 4 days of antibiotics is as effective as about 8 in moderately ill patients (the STOP-IT trial). Persisting fever or illness beyond 5-7 days of antibiotics calls for a search for an uncontrolled source rather than more antibiotics. Empirical antifungals are not routine for community-acquired infection but are considered in critically ill or immunocompromised patients.

Whipple, bariatric and gastric surgery in depth

Pancreaticoduodenectomy removes the pancreatic head, duodenum, distal bile duct and gallbladder and rebuilds three joins (pancreas, bile duct and stomach to jejunum). Morbidity is 30-60% even in high-volume centers, with mortality under 5% there. A pancreatic fistula (ISGPS 2016) is drain fluid of any volume with amylase above 3 times the upper limit of normal serum amylase plus a clinically relevant consequence; without consequence it is a biochemical leak. Fistula drives abscess (10-20%), sepsis and late bleeding. A bile leak shows as bilious drain fluid with drain bilirubin above serum. Delayed gastric emptying (15-45%) means prolonged NG decompression and failure to eat. Hemorrhage within 24 hours is usually technical; later bleeding comes from vessels eroded by leaking enzyme or infection, often a pseudoaneurysm of the gastroduodenal artery stump. Management leans on interventional radiology: percutaneous drainage and embolization.

Leak after sleeve gastrectomy occurs in about 1% (more after revision) and usually in the proximal third of the sleeve. Abou Rached 2014: a heart rate above 120 is a powerful indicator of a leak, fever is the other key sign, and unexplained fever and tachycardia call for CT with IV and water-soluble oral contrast; the abdominal examination may say little. Unstable patients go back to the OR; stable, later leaks may be drained, kept NPO with nutrition support and stented.

Dumping (Masclee 2023) follows gastric surgery, bypass and sleeve: up to 40% after bypass or sleeve. Early dumping (within 1 hour) is a fluid shift into the gut from hyperosmolar chyme: fullness, cramps, diarrhea, palpitations, sweating, faintness. Late dumping (1-3 hours) is reactive hypoglycemia. Treatment steps: smaller, more frequent meals rich in protein and fiber, no rapidly absorbed sugars, no fluids for at least 30 minutes after meals, a dietitian; then acarbose for late symptoms; then octreotide 25-50 mcg SC 15-30 minutes before meals.

Fournier gangrene in depth

Fournier gangrene is a necrotizing soft-tissue infection of the perineal, genital and perianal tissues, usually mixed aerobic and anaerobic (type I). Sources are perirectal abscess, urethral or periurethral infection, recent surgery and retroperitoneal spread from a perforated viscus. Risks include diabetes, alcohol use disorder and immunosuppression; the FDA warned in 2018 about genital necrotizing fasciitis on SGLT2 inhibitors, though large analyses have not confirmed extra risk beyond diabetes itself. Early skin can look like simple cellulitis; pain out of proportion is cardinal but may be blunted by neuropathy, and crepitus, bronzing, bullae and spread beyond the redness mark progression. It travels along the Colles, dartos and Scarpa fascia to the abdominal wall.

Diagnosis is clinical; surgical exploration is the gold standard and scores such as LRINEC must not be used to rule it out (Merck). Treatment is urgent debridement repeated every 1-2 days as needed, broad IV antibiotics narrowed by culture, fluids and organ support. The testes, deep penile tissues and spermatic cord are usually spared because their blood supply arises separately (the testicular arteries come from the aorta); testicular involvement suggests a retroperitoneal source. Reported mortality ranges from about 20-30% for treated necrotizing soft-tissue infection in general (Merck) to about 40% for Fournier gangrene (StatPearls abstract), and delay to surgery raises it. Antibiotic regimens: ICU Basics page CEN: Musculoskeletal and Wound Emergencies.

Classic teaching points kept

These are standard nursing teaching that the open sources read for this page do not state in these words: no heat, enemas or laxatives with suspected appendicitis (they may promote rupture); appendicitis pain that suddenly stops and then spreads with a rigid abdomen means rupture; do not reposition or irrigate an NG tube after gastric or esophageal surgery without an order (it may disrupt the suture line); NG drainage after gastric surgery is bloody at first, darkens within hours and then turns yellow-green, so bright red blood later is reported; keep a sump tube's air vent above the level of the stomach and never clamp it; keep the head of the bed raised with an NG tube; lie down for a short time after meals to slow dumping.

Exam pearls

• Pain out of proportion with a soft abdomen: mesenteric ischemia (AF, stopped anticoagulant, vasopressors).
• Colicky turning constant, fever, tachycardia, rising lactate or wall gas: strangulated bowel, surgery now.
• High-pitched sounds, air-fluid levels and high NG output are expected in simple obstruction.
• Free air absent does not exclude perforation; CT next, never barium.
• Steroids hide peritonitis; analgesia does not.
• Ogilvie plus neostigmine: monitor for bradycardia, atropine ready.
• Venous mesenteric thrombosis without peritoneal signs: heparin, not laparotomy.
• First days after bariatric surgery with HR above 120 and fever: leak until proven otherwise.
• Whipple drain amylase-rich: pancreatic fistula; bilious and bilirubin-rich: bile leak.
• Dumping: small protein meals, fluids between meals, no simple sugars.
• NG not draining with nausea: check the tube and suction before anything else.