How does a history of anorexia nervosa (AN) affect the diagnosis of vaginal discharge?

How a History of Anorexia Nervosa Affects the Diagnosis of Vaginal Discharge

A history of anorexia nervosa should raise suspicion for atypical presentations of anorectal or rectovaginal pathology, as malnutrition in AN leads to mucosal atrophy, reduced gastric acid and pancreatic enzyme secretion, and increased bacterial colonization of the upper gut—all of which can predispose to infectious complications that may present with discharge. 1

Key Physiological Changes in Anorexia Nervosa That Alter Clinical Presentation

Gastrointestinal and Immune Alterations

• Malnutrition in AN causes mucosal atrophy throughout the gastrointestinal tract, including the anorectum, which can alter the typical appearance and symptoms of infectious or inflammatory conditions 1
• Reduced gastric acid secretion and pancreatic enzyme production occur in malnourished AN patients, creating an environment conducive to bacterial overgrowth and altered local flora 1
• Increased bacterial colonization of the upper gut is documented in AN patients, which may extend to lower gastrointestinal and perineal regions 1

Altered Infection Response

• AN patients demonstrate a significantly reduced fever response to bacterial infections, making diagnosis more challenging 2
• Fewer signs and symptoms of infection are present in AN patients compared to controls, leading to delayed recognition 2
• The complication rate from bacterial infections is significantly increased when diagnosis is delayed in AN patients 2

Diagnostic Approach to Vaginal Discharge in AN Patients

Initial Clinical Assessment

• Perform a thorough perineal and anorectal examination to exclude rectovaginal fistula, as these can present with vaginal discharge of stool, gas, or mucopurulent material 1
• Assess for symptoms that may be confused with simple vaginal discharge: fecaluria, pneumaturia (if rectovesicular), dyspareunia, perineal pain, and recurrent vaginal or urinary infections 1
• Check for signs of perianal Crohn's disease, as AN patients may have undiagnosed inflammatory bowel disease that can cause rectovaginal fistulas 1

Laboratory Evaluation

• Obtain a complete blood count early even with minimal symptoms, as AN patients may not mount typical inflammatory responses 2
• Check serum glucose, hemoglobin A1c, and urine ketones to assess metabolic status and rule out diabetes, which can complicate anorectal pathology 1
• Measure inflammatory markers (CRP, procalcitonin, lactate) if any systemic signs are present, as these may be the only indicators of serious infection in AN patients 1, 2

Imaging Considerations

• MRI of the pelvis is the preferred initial imaging modality if rectovaginal fistula is suspected, as it has superior accuracy for detecting fistulous tracts and secondary extensions 1
• CT pelvis with IV contrast should be considered if there are atypical symptoms or concern for abscess, as AN patients may have occult collections without typical inflammatory signs 1
• Water-soluble contrast studies (rectal or vaginal) may help delineate fistulous communications if the diagnosis remains unclear 1

Critical Clinical Pitfalls in AN Patients

Delayed Recognition of Serious Pathology

• Maintain a high index of suspicion for bacterial infections and anorectal complications, as symptoms are frequently absent or diminished in malnourished patients 1, 2
• Do not rely on fever or leukocytosis to rule out infection, as these responses are blunted in AN 2
• Early bacteriologic cultures should be obtained at a lower threshold than in non-AN patients 2

Specific Anorectal Considerations

• Approximately 11% of colovaginal fistulae are caused by malignancy, so imaging findings of soft tissue mass or abnormal lymphadenopathy warrant further investigation even in young AN patients 1
• Obstetric trauma is the most common cause of rectovaginal fistula (88%), but in AN patients with chronic malnutrition, consider atypical etiologies including radiation-like mucosal injury from severe nutritional deficiency 1
• Crohn's disease accounts for 9% of rectovaginal fistulas and must be excluded, especially with recurrent presentations 1, 3

Nutritional Impact on Healing

• Patients who rapidly lose >10% body weight develop demonstrable physiological changes including prolonged sleeping, reduced sexual function, low body temperature, and propensity for severe infections 1
• These physiological changes can mimic or mask symptoms of pelvic pathology, making clinical assessment more challenging 1

Algorithmic Approach

Step 1: Obtain detailed history focusing on:

• Character of discharge (purulent, fecal, gas)
• Associated symptoms (dyspareunia, recurrent infections, perineal pain)
• Bowel symptoms suggesting inflammatory bowel disease 1, 3

Step 2: Physical examination with low threshold for imaging:

• Complete perineal inspection and digital rectal exam 1
• If any abnormality detected or high suspicion → proceed to MRI pelvis 1

Step 3: Laboratory workup regardless of symptom severity:

• CBC, inflammatory markers, glucose screening 1, 2
• Bacteriologic cultures if any concern for infection 2

Step 4: Definitive imaging based on findings:

• MRI pelvis for suspected fistula (rectovaginal or complex anorectal) 1
• CT pelvis with IV contrast for suspected abscess or atypical presentation 1