An Unusual Case of Vaginal Bleeding in a Teenager: Decidual Cast

 

Introduction

Decidual cast is a rare occurrence in gynaecology.¹ A decidual or endometrial cast is the expulsion of the near entirety of the endometrial lining of the uterine cavity, often maintaining the shape of the uterus.² It is also known as membraneous dysmenorrhoea. Many reported cases have been associated with use of a progesterone-containing contraceptive; with some cases reported in teenage girls who passed decidual casts following oral contraceptive pills (OCP) use for the management of heavy menstrual bleeding (HMB).^{3, 4}

 

Case Report

A 16-year-old nulliparous girl presented with a history of sudden passage of tissue per vagina following a short duration of PV bleeding and crampy abdominal pain – both spontaneously resolved after complete tissue expulsion. She had been on regular use of Rigevidon^® (a combined oral contraceptive pill containing ethinylestradiol and levonorgestrel) for three months as a means of contraception with a previously normal menstrual cycle following menarche at age 12.

She had a normal body mass index with an unremarkable physical examination and past medical history. Urine pregnancy test was negative and ultrasound scan showed an empty uterus. Gross examination of the tissue had shown a 14cm long flat fleshy mass with an intrauterine outline confirmed to be a decidual cast on histology examination.

 

Discussion

Decidual cast formation, though a rare occurrence with an obscure aetiology – oestrogen-progesterone imbalance – has been associated with HMB, following ectopic gestations or miscarriages and, infrequently, secondary postpartum hemorrhage. OCP use in teenage girls with pre-existing HMB, as described in literature, might have provoked a cast expulsion. However, our case had no significant risk factors, which would suggest a sudden endometrial hypertrophy with shedding all within three months.

It raises a diagnostic dilemma prior to cast-shedding; sonographic evidence might be lacking in the absence of a polyp, as it was in our case, with investigations and management focused on other causes of secondary menorrhagia thereby increasing anxiety. The mainstay of treatment in young women would be hormonal treatment as often a surgical curettage may not be acceptable as a primary intervention.

 

Conclusion

While decidual cast is not known to have any negative implication on health, it can be a source of distress to patients and a diagnostic challenge to clinicians who are unfamiliar with it.

Passage of tissue per vagina in a non-pregnant woman of reproductive age should raise the suspicion of a decidual cast, more so if the patient is on a progesterone-containing contraceptive.

 

References

1. Sümeyye E, Erdener Ö. Decidual cast: A case report. Journal of Dr Behcet Uz Children’s Hospital 2016; 6(3):234-6 | DOI: 10.5222/buchd.2016.234 
2. Parkes P, Trainor JL, Raval M, Dhar CP. Endometrial cast expulsion: A rare cause of pelvic pain case report and review of the literature. Journal of Adolescent Health 2021; 68(5):1017-9
3. Torres A., Baszak-Radomanska E, Torres K, Paszkowski T, Staskiewicz GJ, Wozniakowska E. A case of unusual course of adolescent menorrhagia: Decidual cast as a side effect of treatment. Fertility and Sterility 2009;92(5):1748.
4. Malik MF, Adekola H, Porter W, Poulik JM. Passage of decidual cast following poor compliance with oral contraceptive pill. Fetal and Pediatric Pathology 2015, 34:2, 103-7. DOI: 10.3109/15513815.2014.970263