Rare Endometrial Cast Reported in Woman Without Hormonal Treatment

A 36‑year‑old woman in India suffered seven to eight months of heavy, prolonged periods, severe cramping, and expelled pieces of tissue with the blood. Examination revealed a soft, reddish‑brown mass about 5 cm × 5 cm at the cervical opening that resembled a mold of her uterus. Obstetricians at Dr. D. Y. Patil Medical College, Hospital and Research Centre in Pimpri, Pune, described the unusual case in the September 2026 issue of the Journal of Clinical and Diagnostic Research.

The condition, called membranous dysmenorrhea, occurs when the uterine lining (endometrium) is shed as a single intact piece rather than fragmenting into small parts. It is commonly linked to hormonal therapies, especially progesterone‑containing contraceptives, or to ectopic pregnancy. In this patient, however, there was no history of hormonal contraception, fertility drugs, herbal remedies, or abnormal hormone levels (TSH, prolactin, FSH, LH, progesterone). Her menstrual history included a six‑month period of amenorrhea following a cesarean delivery.

Drs. Swapnali Sansare and Aneesha Nallapati noted that spontaneous membranous dysmenorrhea is rare and can occur even in the absence of hormonal therapy, underscoring that hormone use is a common association but not a prerequisite for diagnosis.

Ruling Out Miscarriage and Other Look‑Alikes

Because passing a large tissue mass can mimic serious conditions, the clinicians first excluded pregnancy‑related causes. A negative pregnancy test and a pelvic ultrasound—showing a normal‑sized uterus, no focal lesions, a 18‑mm endometrial thickness, and mild free fluid—ruled out retained gestational tissue, endometrial polyps, submucosal fibroids, and ectopic pregnancy. Microscopic analysis of the expelled tissue demonstrated pre‑decidualized endometrium with congested vessels and no pregnancy‑specific features, confirming membranous dysmenorrhea.

A Poorly Understood Condition With Few Proven Treatments

The exact pathophysiology of membranous dysmenorrhea remains unclear, though hormonal imbalance leading to incomplete endometrial breakdown is a leading theory. Evidence‑based treatment options are limited. In this case, the cast was manually extracted with forceps, which provided immediate pain relief. The patient then received three monthly leuprolide acetate injections (a GnRH agonist) and analgesic therapy, and she reported no recurrence over three consecutive menstrual cycles.

Rare, Frightening and Usually Not Dangerous

Passing a decidual cast can be alarming, often producing severe cramps, pelvic pain, heavy bleeding, nausea, and dizziness. The tissue typically appears red or pink and mirrors the shape of the uterine cavity. According to Cleveland Clinic, the condition is generally benign, not associated with infertility, and resolves once the cast is expelled. Nevertheless, because miscarriage and ectopic pregnancy can present with similar symptoms, clinicians must perform a thorough evaluation. Women who notice unusual vaginal bleeding, severe pelvic pain, or pass large tissue masses are advised to seek care and, if possible, preserve or photograph the expelled material for diagnostic clarity.

Key Questions Answered

What is a decidual or endometrial cast?
It is the uterine lining shed as a single intact piece, often shaped like the uterus; the medical term for this occurrence is membranous dysmenorrhea.

What was unusual about this case?
The patient had no exposure to hormonal contraception, fertility drugs, or herbal remedies, and her hormone panel was normal, which challenges the typical hormonal association of endometrial casts.

How did doctors confirm the diagnosis?
They excluded pregnancy, used ultrasound to rule out polyps, fibroids, and other lesions, and examined the tissue under a microscope, finding pre‑decidualized endometrial tissue consistent with membranous dysmenorrhea.

Is passing a decidual cast dangerous?
Usually not; it is not known to cause infertility, but serious conditions such as ectopic pregnancy must be ruled out through proper medical evaluation.

How was the patient treated?
The cast was removed with forceps for immediate relief, followed by three monthly leuprolide injections and pain medication. The patient experienced no further episodes during three menstrual cycles, though a single case cannot prove the treatment’s efficacy.

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