Acute Appendicitis: Often presents with peri-umbilical pain that may later localize to the right lower quadrant. The initial pain around the umbilicus is due to the visceral innervation of the appendix, which is referred to the T10 dermatome, the same level as the umbilicus.

Gastroenteritis: Inflammation of the stomach and intestines can cause abdominal pain that may be peri-umbilical, along with symptoms like diarrhea, vomiting, and fever.
Constipation: Severe constipation can lead to abdominal pain, including around the umbilicus, due to the buildup of feces in the intestines.
Irritable Bowel Syndrome (IBS): A functional disorder of the bowel that can cause abdominal pain, bloating, and changes in bowel habits, with pain sometimes localized around the umbilicus.
Urinary Tract Infection (UTI): While more commonly associated with dysuria and flank pain, a UTI can cause generalized abdominal pain, including peri-umbilical pain, especially in children and the elderly.

Intestinal Obstruction: A mechanical or functional obstruction of the intestine can cause severe abdominal pain, vomiting, and constipation. Early diagnosis is crucial to prevent complications like ischemia and necrosis of the bowel.
Ectopic Pregnancy: A pregnancy that develops outside the uterus can cause abdominal pain, including peri-umbilical pain, and is a medical emergency due to the risk of rupture and severe bleeding.
Ovarian Torsion: Twisting of the ovary can cause severe, sudden onset of abdominal pain, often accompanied by nausea and vomiting. It requires immediate surgical intervention to preserve ovarian function.
Appendicitis in Atypical Locations: Though appendicitis typically presents with right lower quadrant pain, an appendix located in an atypical position (e.g., retrocecal) might cause peri-umbilical pain.

Meckel's Diverticulum: A congenital anomaly of the small intestine that can cause pain, bleeding, or obstruction, especially if it becomes inflamed or infected.
Mesenteric Lymphadenitis: Inflammation of the lymph nodes in the mesentery can mimic appendicitis, causing abdominal pain, including peri-umbilical pain.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause chronic abdominal pain, diarrhea, and weight loss, with pain sometimes localized around the umbilicus.
Abdominal Migraine: A condition seen in children, characterized by recurrent episodes of abdominal pain, often peri-umbilical, accompanied by other migraine symptoms like headache and nausea.