Unusual Case of Vaginal Bleeding in A Teenager Caused by Endometrial Cast: Case Report and Literature Review

Abstract

Introduction Endometrial cast, a rare occurrence in gynaecology, is the expulsion of the near entirety of the endometrial lining of the uterine cavity, often maintaining the shape of the uterus. Also known as membranous dysmenorrhoea and largely associated with use of a progesterone-containing contraceptive; some cases following oral contraceptive pills (OCP) use in adolescence for the management of heavy menstrual bleeding (HMB), have been reported. Case Report A 16-year-old nulliparous girl presented with a sudden passage of tissue per vagina (PV) following a short duration of PV bleeding and short-lasting crampy abdominal pain, after a 3-month regular use of Rigevidon® (a combined oral contraceptive pill (OCP) containing ethinylestradiol and levonorgestrel): a contraceptive choice. Noted was a previously normal menstrual cycle following menarche at age 12 with an unremarkable past medical history, a negative urine pregnancy test and an empty uterus on ultrasound scan. Histological examination of the 14cm-long flat fleshy mass with an intrauterine outline confirmed an endometrial or decidual cast. Discussion Cast formation, with different underlying mechanisms – inadequate estrogen opposition effect on endometrium from dysfunctional oestrogen-progesterone imbalance +/- dysfunctional progesterone-mediated cellular Tissue inhibitors to- and matrix metallopeptidases (TIMP/MMP) – has been associated with HMB, ectopic gestations, miscarriages and secondary postpartum haemorrhage. Our case had no preceding significant risk factors and inadequate sonographic-evidence- a common occurrence in literature. This led to diagnostic and management challenges, increasing anxiety and treatment morbidity. Management in young women should be expectant +/- hormonal treatment. Reassurance with individualised progestogens type and dose will aid contraceptive-compliance. Conclusion While endometrial/decidual cast is not associated with a deleterious health effect, it can be distressing to patients and a diagnostic challenge to clinicians, unfamiliar with it. More research into underpinning pathways and disease associations is needed.