Differentials
Acute appendicitis
SIGNS / SYMPTOMS
Usually presents with right lower quadrant pain, fever, and signs of peritonitis.
INVESTIGATIONS
Urinalysis is negative.
Non-contrast helical computed tomography scan (NCCT) shows dilation of appendix and absence of renal stones.
Ectopic pregnancy
SIGNS / SYMPTOMS
Woman of childbearing age presents with missed menstrual period, right lower quadrant pain, or pelvic pain with some degree of vaginal bleeding or spotting. Cervical motion tenderness may be present on pelvic examination.
INVESTIGATIONS
Urine pregnancy test is positive and serum hCG elevated.
Ultrasound reveals presence of mass in fallopian tubes.
Ovarian cyst
SIGNS / SYMPTOMS
May present with lower pelvic/abdominal discomfort and/or dyspareunia; may be cyclical.
Palpable mass on pelvic examination.
INVESTIGATIONS
Abdominal ultrasound shows cystic adnexal lesion; free fluid in the peritoneum.
NCCT shows absence of renal stones.
Diverticular disease
SIGNS / SYMPTOMS
May present with left lower quadrant pain or abdominal pain as opposed to flank pain.
INVESTIGATIONS
Technetium pertechnetate scan may show enhancement of diverticulum if gastric mucosa is present.
NCCT shows absence of renal stones.
Bowel obstruction
SIGNS / SYMPTOMS
Bowel obstruction patients present with abdominal distension, vomiting, and constipation.
INVESTIGATIONS
Abdominal x-ray may show volvulus.
NCCT shows collapsed bowel with proximal dilation and absence of renal stones.
Acute pancreatitis
SIGNS / SYMPTOMS
History of gallstones or alcohol abuse.
These patients typically have epigastric pain that radiates to the back, as opposed to flank pain.
INVESTIGATIONS
NCCT shows inflammation of the pancreas and absence of renal stones.
The diagnosis of pancreatitis can usually be distinguished from renal stones on clinical grounds, but in rare cases it might be necessary to measure serum amylase and lipase, which are raised in pancreatitis and usually normal in stone disease.
Peptic ulcer disease
SIGNS / SYMPTOMS
May or may not have a history of peptic ulcer disease. Pain is abrupt, severe in intensity, and may be localised to right lower quadrant; often related to eating meals.
INVESTIGATIONS
Erect chest x-ray and abdominal x-ray may show free air under the diaphragm.
Endoscopy shows peptic ulcer.
NCCT shows absence of renal stones.
Gastroenteritis
SIGNS / SYMPTOMS
These patients typically have diffuse abdominal pain and no flank pain. Vomiting is prominent and patient may have diarrhoea.
INVESTIGATIONS
Stool specimen may be positive for culture.
NCCT shows absence of renal stones.
Abdominal aortic aneurysm
SIGNS / SYMPTOMS
Pain typically presents as sudden onset of intermittent or continuous abdominal pain, radiating to the back; patient may collapse.
INVESTIGATIONS
Ultrasound/CT of the abdomen can show the presence of abdominal aortic aneurysm.
Pyelonephritis
SIGNS / SYMPTOMS
Patients may present with costovertebral angle tenderness and urinary symptoms of dysuria, frequency, and hesitancy; flank pain may radiate to back; fever, chills, fatigue may be present.
INVESTIGATIONS
Positive urinalysis and/or urine culture.
Tubo-ovarian abscess
SIGNS / SYMPTOMS
Patients typically present with acute lower abdominal pain, fevers, and vaginal discharge.
INVESTIGATIONS
Pelvic ultrasound shows multilocular adnexal masses.
NCCT shows thick-walled rim-enhancing adnexal masses in the absence of renal stones.
Uteropelvic junction obstruction
SIGNS / SYMPTOMS
Patients may present with intermittent flank or abdominal pain, often worse during brisk diuresis.
INVESTIGATIONS
Renal ultrasound or NCCT shows hydronephrosis without a dilated ureter in the absence of a renal stone.
Testicular torsion
SIGNS / SYMPTOMS
Patients typically present with lower abdominal pain, scrotal pain (testicle), nausea, and/or vomiting.
INVESTIGATIONS
Ultrasound shows enlarged, heterogeneous testicle with decreased or absent Doppler flow.
NCCT shows enlarged oedematous testicle in absence of renal stones.
Ovarian torsion
SIGNS / SYMPTOMS
Patients typically present with lower abdominal pain, nausea, and/or vomiting.
INVESTIGATIONS
Ultrasound shows enlarged, heterogeneous ovary with decreased or absent Doppler flow.
NCCT shows enlarged oedematous ovary in absence of renal stones.
Musculoskeletal back pain
SIGNS / SYMPTOMS
Patient may present with unilateral or bilateral middle and/or lower back pain.
INVESTIGATIONS
Point tenderness upon muscular palpation.
NCCT is normal with absence of renal stones.
Mesenteric ischaemia
SIGNS / SYMPTOMS
Patients typically present with acute peri-umbilical abdominal pain with nausea and vomiting.
INVESTIGATIONS
NCCT shows bowel wall thickening, intestinal pneumatosis, portal venous gas, with absence of renal stones.
Constipation
SIGNS / SYMPTOMS
Patients typically present with left lower quadrant pain and abdominal distension.
INVESTIGATIONS
NCCT shows excessive stool in colon or rectum in absence of renal stones.
Cholecystitis or biliary colic
SIGNS / SYMPTOMS
Patient may present with right upper quadrant and/or epigastric pain, fevers, and leukocystosis.
INVESTIGATIONS
Abdominal ultrasound will show gallstones with gallbladder wall thickening.
NCCT shows gallstones, gallbladder wall oedema, and high attenuation bile in the absence of renal stones.
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