Postpartum Serosal Eosinophilic Gastroenteritis: A Rare Cause of Ascites

Eosinophilic gastroenteritis (EGE) is a rare, heterogeneous inflammatory disorder of the gut wall. Eosinophils are recruited to one or more layers of the gastrointestinal wall. The serosal type is uncommon and can mimic other causes of ascites, such as spontaneous bacterial peritonitis (SBP) or malignancy. We report the case of a woman in her early 30s who presented six weeks postpartum with epigastric pain and recurrent vomiting. She was discharged with oral medications, which did not settle her, resulting in readmission to the hospital. Here, her blood demonstrated marked eosinophilia with eosinophils rising to 8.2 × 10⁹/L. Computed tomography (CT) scan showed ascites and diffuse thickening of the small bowel wall. Cytology of the ascitic fluid revealed eosinophil dominance. No other pathology was identified. Oesophagogastroduodenoscopy (OGD) showed duodenal erythema. A diagnosis of serosal EGE was made based on eosinophilic ascites, small-bowel thickening, and her rapid improvement after treatment with steroids. This case highlights key learning points. Firstly, serosal EGE can occur with normal mucosal biopsies. Secondly, the presence of neutrophilia in the ascitic fluid does not always indicate SBP. Lastly, steroid therapy can be both diagnostic and therapeutic.