NEW ORLEANS — Decidual cast expulsion may occur in young patients using depot medroxyprogesterone acetate Stephen M. Scott, M.D., said during the annual meeting of the North American Society for Pediatric and Adolescent Gynecology.
Although decidual casts are typically associated with ectopic pregnancy and can be confused with spontaneous abortion, Dr. Scott described four cases that suggest decidual casts might be a rare but important side effect associated with use of the hormonal contraceptive—particularly among those exposed after a prolonged period of anovulatory endometrial proliferation.
The first case involved a postanorexic 16-year-old girl who was on depot medroxyprogesterone acetate (DMPA) for contraception and presented 1 month after her first injection. She had a large amount of white tissue protruding from the cervical os.
The patient had experienced weight recovery and signs of estrogen stimulation at the time of the injection, but also had persistent amenorrhea at the time of injection.
The second case involved a 20-year-old with cerebral palsy and mental retardation, who was using DMPA for the treatment of dysfunctional uterine bleeding. She presented with tissue passing from the vagina 3 weeks after her first injection.
The third case involved an 11-year-old with factor VIII deficiency, who was treated with DMPA to control hemorrhaging that occurred at her first menarche 8 months earlier. She presented with severe cramps and the sensation of a mass in the vagina.
An examination revealed white tissue protruding from the cervical os.
The fourth case involved a 19-year-old who had a vaginal delivery 5 months earlier and who at 3 months post partum was breast-feeding and amenorrheic. She began using DMPA for contraception at that time, and 2 months later, she presented with bleeding and cramping.
As with the first three cases, examination revealed a large amount of tissue at the cervical os.
The findings in each case were consistent with decidual cast expulsion, and all patients had a negative result on a pregnancy test. The removal of the protruding tissue resulted in symptom resolution, said Dr. Scott of the University of Colorado, Denver.
“We probably all feel comfortable with the fact that decidual cast formation is just an intense reaction and variant of menstruation, but because it is rare and unpredictable, we don't really have a great idea of what elements are needed in order to form a decidual cast and pass it,” Dr. Scott said.
In theory, however, decidual cast formation can be expected when prolonged endometrial proliferation precedes progesterone exposure, leading to a thicker endometrial layer. When the progesterone levels falter, the likelihood of decidual cast formation may be increased, he said.
Although these cases involved varying clinical scenarios, it can be argued that similar hormonal events may have led to the decidual cast formation and passage, he added.
The first three patients had an extended period of amenorrhea with estrogen-only stimulation of the endometrial lining, and thus endometrial proliferation. The fourth patient also may have had prolonged estrogen production with resumption of ovarian estrogen production late in breast-feeding.
DMPA treatment in these patients would then have resulted in a high level of progesterone exposure followed by a gradual decline in progesterone levels that might have led to the decidual casts, he explained.
In most of these cases, the decidual casts were, understandably, very frightening for the patient and/or parent, he said.
For this reason, as well as to fully inform patients about the potential effects of DMPA and to promote treatment compliance, patient counseling should include discussion of decidual cast expulsion as a rare side effect associated with the drug.
Furthermore, because 1% of DMPA failures are ectopic pregnancies (although DMPA is not a known cause of ectopic pregnancies), and because decidual casts and ectopic pregnancies can be easily confused, patients using DMPA who experience tissue passage should be advised to bring the specimen in for evaluation, and should undergo a pregnancy test to avoid delays in diagnosis of ectopic pregnancies, he said.