17 year old male pt. Presented with c/o abdominal pain nausea vomiting. Acute complain. We were suspecting acute appendicitis. Now what can it be. Tlc is normal.
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17-Year-Old Male: Acute Abdomen with Normal TLC - Differential Diagnosis
First, the critical point about normal TLC
A normal white blood cell count does NOT exclude acute appendicitis. Leukocytosis is present in ~90% of appendicitis cases, but a normal WBC is found in 10% of cases - it must never be used in isolation to rule out appendicitis. (Sabiston Textbook of Surgery, p. 2039)
Combined WBC + CRP have a sensitivity as high as 98%, but if both are normal in a patient with low pretest probability, pathologically confirmed appendicitis becomes unlikely. Normal TLC in this patient should instead broaden your differential. (Tintinalli's Emergency Medicine, p. 424-426)
Differential Diagnosis - Prioritized for This Patient (Adolescent Male)
Most Likely Alternatives (non-surgical mimics)
| Condition | Distinguishing Features |
|---|---|
| Mesenteric Adenitis | Most common mimic in this age group. Colicky pain, may have cervical lymphadenopathy, often post-viral. Normal or mildly elevated WBC. |
| Acute Gastroenteritis | Prominent vomiting/diarrhoea, diffuse cramping, no localized peritonism, often multiple affected contacts |
| Yersinia / Campylobacter enterocolitis | Terminal ileitis picture, may mimic appendicitis exactly; serology diagnostic |
| Mesenteric ischemia/infarction | Pain out of proportion to exam |
Surgical Causes to Rule Out
| Condition | Key Points |
|---|---|
| Acute appendicitis (still #1) | Do NOT dismiss it just because TLC is normal - 10% have normal WBC |
| Meckel's Diverticulitis | Clinically indistinguishable from appendicitis; pain may be central or left-sided; history of prior episodic pain or lower GI bleeding |
| Intestinal obstruction | Colicky pain, vomiting, constipation, distension |
| Intussusception | Less likely at 17 years (more common <2 yrs), but can occur as a lead point (polyp, Meckel's) |
| Torsion of testis | Always ask - may present with abdominal pain and vomiting without obvious scrotal symptoms; examine scrotum |
Urological Causes
| Condition | Key Points |
|---|---|
| Right ureteric colic / nephrolithiasis | Colicky, radiates to groin; haematuria on urinalysis |
| Right pyelonephritis | Fever, loin pain, positive urinalysis (pyuria) |
Medical / Non-Surgical Causes (easy to miss)
| Condition | Key Points |
|---|---|
| Right basal pneumonia / pleurisy | Minimal abdominal tenderness, marked pyrexia, auscultation abnormal; CXR diagnostic |
| Diabetic ketoacidosis | Especially if undiagnosed T1DM; check blood glucose, urinary ketones |
| Crohn's disease (terminal ileitis) | Doughy mass may be palpable, weight loss, diarrhoea history |
| Henoch-Schonlein Purpura (IgA vasculitis) | Preceding sore throat/URTI, palpable purpura on extensor surfaces/buttocks, microscopic haematuria - examine skin carefully |
| Porphyria | Rare, but causes acute severe abdominal pain |
(Bailey & Love's Short Practice of Surgery 28th Ed., Table 76.1; Goldman-Cecil Medicine, Table 128-1)
Immediate Next Steps
- Clinical scoring - Apply the Alvarado/MANTRELS score: migration of pain, anorexia, nausea/vomiting, RLQ tenderness, rebound, fever, leukocytosis. Score 5-6 = possible appendicitis; 7+ = probable appendicitis. (Tintinalli's, p. 419)
- Investigations:
- Urinalysis (haematuria → renal colic; pyuria → UTI/pyelonephritis)
- CRP and neutrophil differential (CRP may be elevated even when WBC is normal)
- Blood glucose + urine ketones (rule out DKA)
- CXR (rule out right basal pneumonia)
- USS abdomen - first-line imaging; if inconclusive, proceed to CT abdomen (sensitivity/specificity >94% for appendicitis)
- Examine the scrotum - testicular torsion is a time-critical diagnosis in this age group
- Serial examination - if diagnosis remains unclear, repeat abdominal exam every 2-4 hours
Bottom line: Normal TLC should not provide false reassurance. Appendicitis is still the leading diagnosis, but a normal WBC in a 17-year-old male particularly points toward mesenteric adenitis, Meckel's diverticulitis, renal colic, basal pneumonia, or Yersinia enterocolitis as top alternatives. Testicular torsion must always be actively excluded in any adolescent male with abdominal pain.
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