Pulsatile abdominal mass

A pulsatile abdominal mass is a swelling in the epigastrium or central abdomen that visibly or palpably pulsates in time with the heartbeat.

The central question is whether it is an abdominal aortic aneurysm (or another aneurysm), a normal or tortuous aorta felt through a thin abdominal wall, or a non vascular mass lying on the aorta that merely transmits its pulsation. A true expansile pulsation (the examining fingers are pushed apart sideways as well as upward) points to an aneurysm.

Clinical relevance. Abdominal aortic aneurysm (aortic diameter 3.0 cm or more) affects about 4% to 8% of men over 65 and about 1% of women. Rupture carries an overall mortality of 80% to 90% (about 50% reach hospital, and 30% to 50% of those die peri-operatively).

Most unruptured aneurysms are silent and found by examination, imaging for other reasons, or screening. Detection and timely repair reduce deaths. Missing a symptomatic aneurysm is a leading cause of avoidable death in older men presenting with back or abdominal pain.

Classification.

• True aneurysm: abdominal aortic aneurysm (infrarenal in 90%), iliac artery aneurysm, visceral aneurysms (splenic, hepatic, renal, mesenteric), femoral and popliteal aneurysms (often coexist).
• Aneurysm by cause: degenerative atherosclerotic, inflammatory (thick wall, periaortic fibrosis, raised ESR), infective (mycotic), connective tissue disease (Marfan syndrome, Ehlers-Danlos syndrome, Loeys-Dietz syndrome), arteritis (Takayasu, giant cell, Behcet), traumatic pseudoaneurysm, post dissection.
• Non aneurysmal pulsation: tortuous or ectatic aorta (older women, hypertension), thin body habit with normal aorta, lumbar lordosis, kyphosis.
• Transmitted pulsation: pancreatic tumour, retroperitoneal lymphadenopathy, abscess, retroperitoneal tumour, para aortic mass, gastric or omental mass, enlarged liver (pulsatile in tricuspid regurgitation), right ventricular hypertrophy (epigastric pulsation).

Mechanism. Medial degeneration with loss of elastin and collagen, chronic inflammation, proteolysis and wall stress cause progressive dilatation. Laplace tension rises with diameter, so risk of rupture increases steeply over 5.5 cm. Smoking, male sex, age over 65, family history, hypertension and atherosclerosis are the main risks.

History.

• Often asymptomatic: found on examination or imaging.
• Symptoms: abdominal, back, flank or groin pain (constant, boring), pulsating sensation, early satiety, bloating, ureteric colic from hydronephrosis, claudication, blue toe syndrome, leg swelling (venous compression), weight loss and fever (inflammatory or infected aneurysm).
• Rupture: sudden severe abdominal or back pain, collapse, syncope, pulsatile mass (triad of pain, hypotension and a pulsatile mass is present in under 50%).
• Risk factors: smoking (current and past), age over 65, male sex, hypertension, hypercholesterolaemia, coronary or peripheral artery disease, family history of aneurysm (first degree relative; risk 4 to 5 times higher), Marfan syndrome and bicuspid aortic valve, previous aneurysm.
• Infection risk: bacteraemia, endocarditis, injecting drug use, immunosuppression, tuberculosis, syphilis, salmonellosis, recent arterial procedure.
• Drugs: fluoroquinolones (associated with aneurysm rupture and dissection), corticosteroids, anticoagulants.
• Systemic: fever, malaise, weight loss, back pain at night, other aneurysm sites.

Examination.

• Vital signs (hypotension, tachycardia, pallor, sweating) and abdominal distension.
• Palpate deep in the epigastrium and umbilical region with one hand each side of the midline; an aneurysm is expansile (fingers displaced laterally and anteriorly), whereas a transmitted pulsation moves fingers only anteriorly. Assess size by width between the fingers (over 3 cm width is abnormal; palpation underestimates size, particularly in obese patients).
• Tenderness over the mass (suggests expansion, leak or inflammation), bruit over the mass, femoral and popliteal pulses and aneurysms (popliteal and femoral aneurysms coexist in 10% to 15%), peripheral pulses, signs of distal embolisation, leg ischaemia.
• Flank ecchymosis (Grey Turner sign) or groin bruising suggests retroperitoneal bleeding.
• Cardiac: murmurs (aortic regurgitation, tricuspid regurgitation), blood pressure in both arms.
• Marfanoid features, joint hypermobility, skin stretch, lens dislocation, striae.
• Other sites of mass: liver, kidneys, nodes, bladder; rectal and genital examination.

Red flags.

• Pulsatile mass with abdominal or back pain, tenderness, hypotension or collapse (ruptured or symptomatic aneurysm).
• Syncope with any abdominal or back pain in an older man.
• Tender, expanding or rapidly growing mass; new bruit.
• Fever, raised inflammatory markers and an aortic mass (infected or inflammatory aneurysm).
• Distal embolisation (blue toes), claudication or limb ischaemia.
• Pulsatile mass with a known connective tissue disease.
• Haematuria, hydronephrosis or gastrointestinal bleeding (aorto enteric fistula, especially after previous aortic graft).
• Pulsatile mass with weight loss or cachexia (tumour).

Aneurysms. Infrarenal abdominal aortic aneurysm, suprarenal and thoracoabdominal aneurysm, iliac artery aneurysm, splenic, hepatic, renal and mesenteric artery aneurysms (including after pancreatitis), mycotic aneurysm, inflammatory aortic aneurysm, pseudoaneurysm (post trauma or surgical), ruptured aneurysm and contained leak, aortic dissection with aneurysmal dilatation, aortocaval fistula.

Normal or ectatic aorta. Thin patient with prominent aorta, lordosis, tortuous aorta in hypertension and ageing, ectatic aorta (under 3 cm).

Transmitted pulsation from adjacent masses. Pancreatic carcinoma and pancreatic pseudocyst, retroperitoneal lymphadenopathy (lymphoma, testicular and other tumours, tuberculosis), retroperitoneal sarcoma, gastric tumour, omental or mesenteric mass, ovarian and uterine masses, abscess, gastric dilatation (succussion). Other epigastric pulsation. Right ventricular hypertrophy and heave, tricuspid regurgitation (pulsatile liver), hepatic arteriovenous malformation, hyperdynamic circulation (anaemia, thyrotoxicosis, aortic regurgitation), anxiety.

Vascular malformations. Arteriovenous fistula, aortocaval fistula, vascular tumours.

1. Unstable patient with suspected rupture: do not delay for imaging beyond a bedside ultrasound. Take to theatre or CT with a vascular surgeon.
2. Stable patient: abdominal ultrasound (sensitivity and specificity close to 100% for aneurysm, accuracy within 0.3 cm). Measure the maximum outer to outer anteroposterior diameter; a diameter of 3.0 cm or more is an aneurysm. Ultrasound also looks for iliac extension.
3. CT angiography of the aorta (thoracic to femoral) for pre-operative planning, symptomatic or suspected rupture. It shows retroperitoneal haematoma, extravasation, thrombus and calcification, wall thickening, periaortic stranding, fistula, and anatomy for endovascular repair. Use contrast enhanced MR angiography when contrast is contraindicated.
4. Blood tests: full blood count, group and crossmatch (at least 6 units in rupture), urea, creatinine, electrolytes, coagulation, lactate, troponin, ECG. Add ESR and C reactive protein for inflammation, blood cultures and microbiology for suspected infection, syphilis serology, and autoimmune screens where arteritis is suspected.
5. Cardiovascular and fitness assessment before elective repair: ECG, echocardiography, lung function, coronary risk assessment, carotid duplex.
6. Screening: ultrasound of the abdominal aorta once at age 65 in men (and in women over 65 with risk factors such as smoking or family history), and in first degree relatives of those with aneurysm from age 50 to 55. Look at iliac and popliteal arteries.
7. Genetic testing and aortic imaging (thoracic and abdominal) in suspected connective tissue disease.
8. Non vascular mass: CT with contrast of abdomen and pelvis, tumour markers, endoscopic ultrasound, and biopsy where indicated.

Limits. Clinical examination detects only about 50% to 75% of aneurysms of 4 to 5 cm and fewer in obese patients. A negative examination does not exclude aneurysm. Ultrasound may be limited by bowel gas and obesity. A normal aorta may be palpated as pulsatile in thin patients.

Ruptured or symptomatic abdominal aortic aneurysm (emergency).

• Call the vascular team and theatre at once. Insert two large bore intravenous cannulas, group and crossmatch, activate the major haemorrhage procedure, and give oxygen.
• Permissive hypotension: target systolic pressure 70 to 90 mmHg (maintain consciousness and a palpable radial or femoral pulse) until aortic control.
• Avoid large volumes of crystalloid (small boluses of 250 mL only). Give blood products early in a 1:1:1 ratio of red cells, plasma and platelets.
• Tranexamic acid 1 g intravenously over 10 minutes then 1 g over 8 hours. Keep the patient warm. Give analgesia in small doses (morphine 2.5 mg intravenously) without lowering pressure.
• Emergency repair: endovascular repair when anatomy is suitable (lower 30 day mortality), otherwise open repair with aortic clamp. Use aortic balloon occlusion in unstable patients.
• Mortality after rupture is about 25% to 40% when repaired and over 90% without.
• Do not delay transfer to a repair centre.
• Postoperative intensive care: fluid and blood balance, abdominal compartment syndrome (bladder pressure over 20 mmHg), kidney and bowel ischaemia, myocardial injury.

Asymptomatic abdominal aortic aneurysm (surveillance and risk reduction).

• Ultrasound surveillance by size: 3.0 to 4.4 cm, every 12 months; 4.5 to 5.4 cm, every 3 months.
• Refer for repair assessment at 5.5 cm or more in men (5.0 cm or more in women), growth over 1 cm in a year or over 0.5 cm in 6 months, symptoms, saccular morphology, or rapidly increasing size.
• Elective repair: open surgical graft or endovascular aneurysm repair (EVAR), chosen by a vascular multidisciplinary team. EVAR is preferred in older, higher risk patients with suitable anatomy and needs lifelong surveillance for endoleak. Operative mortality is about 1% to 5% for elective repair.
• Stop smoking: nicotine replacement patch 21 mg daily for 6 weeks, then 14 mg for 2 weeks and 7 mg for 2 weeks.
• Alternatively, varenicline 0.5 mg daily for 3 days, 0.5 mg twice daily for 4 days, then 1 mg twice daily for 12 weeks.
• Blood pressure target under 130/80 mmHg (ramipril 2.5 to 10 mg daily, with amlodipine 5 to 10 mg daily or a beta blocker if needed).
• Atorvastatin 40 to 80 mg daily; aspirin 75 mg daily for cardiovascular protection; control diabetes; exercise within limits.
• Avoid fluoroquinolones and unnecessary heavy straining or isometric exertion.
• Beta blockers and doxycycline do not slow aneurysm growth reliably.

Mycotic and infected aneurysm. Blood cultures, urgent CT, broad antibiotics (for example vancomycin 15 to 20 mg/kg every 8 to 12 hours plus ceftriaxone 2 g daily or piperacillin-tazobactam 4.5 g every 6 hours, adapting to culture), surgical debridement and in situ or extra anatomic reconstruction. Give prolonged antibiotics for 6 weeks to lifelong when a graft is used.

Inflammatory aneurysm. Surgical or endovascular repair with prednisolone 40 to 60 mg daily tapering over 2 to 3 months for aortitis, and treatment of IgG4 related disease or vasculitis.

Aortocaval or aorto enteric fistula. Emergency surgical repair, resuscitation, antibiotics (for example piperacillin-tazobactam 4.5 g every 6 hours). Gastrointestinal bleeding after aortic repair is a fistula until proved otherwise (CT, endoscopy).

Other aneurysms.

• Splenic: treat when 2 cm or more in women of childbearing age or any pregnancy, symptomatic, or growing (embolisation or splenectomy).
• Renal and visceral: embolisation or stent graft for 2 cm or more or symptoms.
• Iliac: repair at 3.5 cm or more.
• Popliteal: repair at 2 cm or more or if thrombosed or embolising.
• Femoral: repair at 2.5 cm or more.

Non vascular mass. Targeted investigations and referral to oncology, gastroenterology or surgery.

Normal prominent aorta. Reassure after ultrasound; no surveillance needed.

Monitoring. Surveillance ultrasound by size (3.0 to 4.4 cm every 12 months, 4.5 to 5.4 cm every 3 months). Blood pressure and lipids; medication adherence. After EVAR, CT or duplex at 1 month, 12 months and then annually (endoleak, migration, sac size). Renal function after contrast. Screening of first degree relatives and of other peripheral aneurysms.

Referral and escalation. Vascular surgery for all aortic aneurysms of 3.0 cm or more, symptomatic or ruptured aneurysms, and for infected, inflammatory and visceral aneurysms. Cardiology and anaesthesia for pre-operative fitness. Genetic and cardiology services for connective tissue disease. Infectious diseases for mycotic aneurysm. Oncology or surgery for non vascular masses.

Admission. Any suspected rupture, symptomatic or tender aneurysm, rapid expansion, distal embolisation, infected or inflammatory aneurysm, or inability to arrange urgent imaging.

Safety netting. Return by emergency services for sudden severe abdominal, back or groin pain, collapse, fainting, black or bloody stools, a cold or blue toe or foot, or rapid abdominal swelling. Stop smoking, take medicines daily and attend surveillance scans.

Special groups.

Women: aneurysms rupture at smaller diameters (under 5.5 cm) and repair thresholds are lower.

• Marfan syndrome and Ehlers-Danlos syndrome: lower thresholds and genetic counselling.
• Pregnancy: aneurysm in connective tissue disease or splenic artery aneurysm rupture is catastrophic.
• Older adults: frailty and comorbidity decide between repair, endovascular repair and conservative care.
• Younger patients: exclude infection and connective tissue disease.
• First degree relatives: screening from age 50 to 55.
• Endemic regions: tuberculous, salmonella and syphilitic aneurysms, and Takayasu arteritis.