What are the causes of foul-smelling umbilical discharge and abdominal pain?

Foul-Smelling Umbilical Discharge with Abdominal Pain: Differential Diagnosis

This presentation of foul-smelling, liquid umbilical discharge with abdominal pain requires urgent evaluation for omphalitis with potential intra-abdominal complications, as this combination carries significant morbidity and mortality risk even when pain is the only systemic symptom. 1, 2

Primary Diagnostic Considerations

Bacterial Omphalitis (Most Likely)

• Staphylococcus aureus is the most frequently reported causative organism, followed by Group A and B Streptococci, and Gram-negative bacilli including E. coli, Klebsiella, and Pseudomonas species 1, 2
• The foul-smelling, liquid discharge (described as "like smegma but liquidy") strongly suggests bacterial infection with purulent material 2
• Abdominal pain indicates potential progression beyond superficial infection to deeper structures 2

Urachal Remnant Infection (Critical to Exclude)

• Infected urachal remnants present with umbilical discharge and abdominal pain, representing a direct connection between the umbilicus and bladder dome 3, 4
• This embryological remnant can cause recurrent infections and requires surgical excision for definitive treatment 3, 4
• Urachal pathology should be suspected when discharge persists or recurs despite conservative management 4, 5

Patent Vitello-Intestinal Duct

• This represents a connection between the umbilicus and intestine, presenting with discharge that may be serous, purulent, or even fecal 5
• Associated abdominal pain suggests potential intestinal involvement or peritoneal irritation 5

Umbilical Pilonidal Sinus

• Can present with painful bloody or purulent discharge from the umbilicus 6
• Often misdiagnosed as urachal cyst on initial imaging 6

Immediate Diagnostic Workup

Clinical Assessment

• Examine for periumbilical erythema, tenderness, and edema—these indicate active infection requiring urgent intervention 1, 2
• Assess for systemic signs including fever and lethargy, which indicate potential sepsis, intra-abdominal abscess, portal/umbilical vein thrombophlebitis, peritonitis, or bowel ischemia 2
• Note that case-fatality rates as high as 13% have been reported for omphalitis with complications 2

Laboratory and Imaging

• Culture the discharge immediately to identify bacterial pathogens and guide antibiotic therapy 1, 2
• CT abdomen and pelvis with IV contrast is the preferred imaging modality for evaluating nonlocalized abdominal pain with suspected infection, as it provides rapid, comprehensive assessment 7
• CT will identify urachal remnants, abscesses, hernias with fat necrosis, or other structural abnormalities 3, 8
• Ultrasound can detect urachal sinus or cysts but has lower sensitivity than CT for intra-abdominal pathology 3, 4

Management Algorithm

For Simple Omphalitis Without Systemic Signs

• Apply topical antiseptics and maintain local hygiene 1
• Initiate empiric antibiotics covering S. aureus, Streptococci, and Gram-negative organisms 1, 2

For Omphalitis with Abscess or Abdominal Pain

• Perform incision and drainage of any umbilical abscess 1
• Initiate broad-spectrum IV antibiotics covering S. aureus, Streptococci, Gram-negative bacilli, and anaerobes 1
• Hospital admission is warranted given the combination of discharge and abdominal pain 7

For Structural Abnormalities

• Surgical excision is required for urachal remnants, patent vitello-intestinal duct, persistent pilonidal sinus, or failed conservative treatment 1, 3, 4, 5
• Complete excision is curative and prevents complications including neoplastic transformation 4

Critical Pitfalls to Avoid

• Do not dismiss this as simple infection—the umbilicus provides direct vascular access, and even painless discharge can progress to life-threatening complications 1, 2
• Conservative treatment alone usually fails when structural abnormalities (urachal remnants, patent vitello-intestinal duct) are present, necessitating early surgical referral 5
• Delayed diagnosis and treatment of patent vitello-intestinal duct has resulted in mortality from sepsis and metabolic complications 5
• The combination of foul discharge and abdominal pain mandates imaging to exclude intra-abdominal extension of infection 7, 2