title: Decidual Bleeding as a Cause of Spontaneous Hemoperitoneum in Pregnancy and Risk of Preterm Birth.
abstract: BACKGROUND
  Spontaneous hemoperitoneum in pregnancy (SHiP) is a rare, life-threatening event, particularly relevant to women with endometriosis or deciduosis.
  
  
  METHODS
  To determine the type of lesions leading to SHiP, a literature search was conducted among all published SHiP cases. From a total of 1,339 publications, information on pathological findings at the bleeding site with histological data was found in 24 case reports (16 pregnant, 8 postpartum).
  
  
  RESULTS
  Among pregnant women (81% primigravida), 75% had a diagnosis of endometriosis and 25% of deciduosis. Among postpartum women (38% primiparous), 63% had a diagnosis of deciduosis and 25% of endometriosis. In all cases except one, decidual cells, with or without glandular structures, were present at the bleeding site. Decidual vessels were described in 7 cases and all exhibited vascular changes, including distension of the lumen, medial disorganization, or loss of vascular integrity. These vessels were significantly different from arteries seen in the secretory endometrium, showing that structural modifications take place during the initial stage of the remodelling of placental bed spiral arteries.
  
  
  CONCLUSIONS
  During pregnancy, a link seems to exist between ectopic decidualization, particularly that occurring in endometriotic foci, and occurrence of SHiP. In addition, subclinical decidual bleeding may be a potential risk factor for preterm labour.
authors.affiliation: VU University Medical Centre, Endometriosis Centre VUmc, Department of Reproductive Medicine, Amsterdam, The Netherlands.
authors.forename: Marit C I
authors.initials: MCI
authors.lastname: Lier
authors.forename: Ivo A
authors.initials: IA
authors.lastname: Brosens
authors.forename: Velja
authors.initials: V
authors.lastname: Mijatovic
authors.forename: Marwan
authors.initials: M
authors.lastname: Habiba
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Benagiano
mesh_terms: D000328:Adult; D003656:Decidua; D004715:Endometriosis / Q000150:complications; D005260:Female; D006465:Hemoperitoneum / Q000209:etiology*; D006801:Humans; D007231:Infant, Newborn; D010920:Placenta / Q000098:blood supply / Q000473:pathology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000209:etiology*; D047928:Premature Birth / Q000209:etiology*; D012307:Risk Factors; D014592:Uterine Hemorrhage / Q000150:complications*
keywords: Deciduosis; Endometriosis; In vitro fertilization; Pregnancy complications; Spontaneous hemoperitoneum