Answer: Option A - Solid Infrequent Stool with Soiling
Option A (solid infrequent stool with soiling) supports the diagnosis of functional constipation. This presentation is consistent with the Rome criteria for functional constipation, which includes infrequent bowel movements and hard/lumpy stools, while fecal soiling (encopresis) is a common complication of chronic constipation in children due to overflow incontinence around impacted stool 1, 2.
Why Option A is Correct
- Infrequent, hard stools are a cardinal feature of functional constipation, defined by the Rome III/IV criteria as fewer than 3 bowel movements per week and/or lumpy or hard stool 1, 3
- Fecal soiling (encopresis) occurs in functional constipation when liquid stool leaks around a fecal impaction, creating paradoxical "diarrhea" or soiling despite underlying constipation 4
- This combination is particularly common in pediatric functional constipation, where overflow incontinence develops as a complication of chronic fecal retention 4
Why Option B is Incorrect
- Sacral dimple and loss of anal tone are alarm features suggesting organic pathology, not functional constipation 1, 2
- These findings raise concern for spinal dysraphism (tethered cord, spina bifida occulta) or neurological disease causing secondary constipation 4
- Loss of anal tone on digital rectal examination indicates potential neuromuscular dysfunction requiring imaging (MRI of spine) and neurological evaluation 5, 6
- The diagnosis of functional constipation presumes the absence of structural or biochemical explanation for symptoms 3
Why Option C is Incorrect
- Two stools per day with normal intake does not meet criteria for constipation 1, 2
- Functional constipation requires fewer than 3 bowel movements per week as one of the diagnostic criteria 1, 3
- Normal stool frequency (typically defined as 3 bowel movements per week to 3 per day) with normal dietary intake suggests normal bowel function, not constipation 3
Key Diagnostic Principles
- Functional constipation is diagnosed using positive symptom-based criteria (Rome III/IV) requiring at least 2 of the following for ≥12 weeks: straining, lumpy/hard stool, sensation of incomplete evacuation, anorectal blockage, manual maneuvers, or <3 bowel movements per week 1, 3
- The diagnosis requires exclusion of alarm features such as abnormal neurological examination, structural anorectal abnormalities, or signs of organic disease 3, 4
- Fecal soiling in the context of constipation is overflow incontinence, not true diarrhea, and supports rather than contradicts the diagnosis of functional constipation 4