Background: Over the last few decades, the caesarean section has increased all over the world. More issues are likely to be observed as caesarean section rate increases. Infection is the leading cause of maternal morbidity and mortality. Postoperative peritonitis and ascites are very rare complications in lower segment caesarean section delivery. The final cause is unknown, but sometimes it causes due to allergic or inflammatory reaction of the peritoneum. If it occurs after caesarean then creates very serious issues with the woman health. Case Presentation: Here we are mentioning a very rare surgical case of peritonitis with ascites of unknown cause after lower segment caesarean section delivery. In this case, on physical examination and investigation, it was found that, after the caesarean patient has developed severe abdominal pain, fever, nausea, vomiting, abdominal distension, swelling on face and foot. To overcome this sudden issue, an emergency exploratory laparotomy was done. During the surgical exploration of the abdominal cavity maximum amount of clear fluid was seen and that was aspirated by suctioning and peritoneal lavage was given. There was no sign of tissue or organ damage by surgery or no other abnormality was detected during operation. No bacterial growth observed in fluid cultures on the investigation of fluid drained from the abdomen. The working diagnosis was finalized by surgeon i.e. reactive peritonitis with ascites. After expert surgical management and excellent nursing care patient was discharged with full recovery. Conclusion: In this study, we mainly focus on expert surgical management and excellent nursing care helped in managing the complicated case very nicely. All the patient response was positive for conservative and nursing management and after treatment, the patient was discharged without any postoperative complications and satisfaction with full recovery.