RCOG World Congress 2025

Pregnancy related peritoneal deciduosis, Diagnostic dilemma at caesarean section:

• Objective:

• Ectopic decidua ( presence of decidual tissue outside of uterus) has been observed most often in the ovaries, uterus, and cervix. Peritonealdeciduosis ( presence of decidual tissue in peritoneum) is less frequent and usually an asymptomatic incidental finding during laparotomy for a caesarean section.

• We are presenting here an interesting case of pregnancy related peritoneal deciduosis.

• Case report:

• A 35-year-old woman, P1 previous caesarean section, underwent category 2 caesarean section at 40 weeks gestation because of foetal distress. She had history of gastric ulcer rupture with peritonitis for which she had laparotomy and repair.

• The laparotomy revealed extensive greenish brown small deposits on the uterus, tubes, ovaries, parietal,visceral peritoneum, bowel and omentum.

• Intraoperatively surgical evaluation was performed, and biopsies were taken from these deposits and sent for histology.

• The biopsy showed fragments of peritoneal tissue bearing clusters of large, rounded cells with abundant pale
eosinophilic cytoplasm, large bland nuclei with prominent nucleoli in keeping with deposits of decidual tissue. Hence, diagnosis of peritoneal deciduosis was made.

• Discussion:

• Peritoneal deciduosis is usually an incidental histological finding. It may present a diagnostic dilemma by mimicking grossly peritoneal carcinomatosis or tubercles .Decidual transformation of the peritoneum arises from a progesterone-induced metaplasia of the subserosal stromal cells.

• The pathophysiology of these lesions is not yet fully understood. The phenomenon is most often benign, with a favourable outcome in the post-partum and without follow-up.

• In our case it was incidental finding at time of surgery, however can present with abdominal pain, bloating, and bowel symptoms. Because of the wide range of clinical presentations, the clinical diagnosis of ectopic decidua is difficult. Furthermore, imaging is not specific. The discovery of such lesions should lead to the realization of systematic biopsies for histological examination and rule out other causes.

• Conclusion:

Pregnancy related peritoneal deciduosis develops due to effect of progesterone in pregnancy, often a totally reversible phenomenon.

Immunohistochemistry can be helpful in differentiating it from malignant mesothelioma and metastatic tumour.

References:

1.Piccinni DJ, Spitale LS, Cabalier LR, Dionisio de Cabalier ME. Decidua en la superficieperitoneal imitando nódulos metastásicos. Hallazgo durante una intervención cesárea[Decidua in the peritoneal surface mimicking metastatic nodules. Findings during cesareansection]. Rev Fac Cien Med Univ Nac Cordoba. 2002;59(1):113-6. Spanish. PMID: 12934253.

2.Bolat F, Canpolat T, Tarim E. Pregnancy-related peritoneal ectopic decidua (deciduosis): morphological and clinical evaluation. Turk Patoloji Derg. 2012;28(1):56-60. doi: 10.5146/tjpath.2012.01098. PMID: 22207433.

3.Fenjvesi A, Zivković S. [Deciduosis peritonei--a case report]. Med Pregl. 2005 Mar-Apr;58(3-4):196-9. Serbian. doi: 10.2298/mpns0504196f. PMID: 16526221.

4.Canlorbe G, Goubin-Versini I, Azria E, Abdul-Razak R, Muray JM. La déciduoseectopique: variabilités de présentation pendant la grossesse et diagnostics différentiels[Ectopic decidua: variability of presentation in pregnancy and differential diagnoses]. Gynecol Obstet Fertil. 2012 Apr;40(4):235-40. French. doi: 10.1016/j.gyobfe.2012.02.008. Epub 2012 Mar 30. PMID: 22464747.

RCOG World Congress 2025

Pregnancy related peritoneal deciduosis, a diagnostic dilemma at caesarean section:

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