Missed abortion (silent miscarriage)

Missed abortion (silent miscarriage)

Definition- When the fetus is dead and retained inside the uterus for a variable period, it is called missed abortion or silent miscarriage or early fetal demise.

Pathology: the cause of prolonged retention of the dead fetus in the uterus is not clear. Beyond 12 weeks, the retained fetus becomes macerated or mummified. The liquor amnii gets aborted and the placenta becomes pale, thin and may be adherent. Before 12weeks, the pathological process differs when the ovum is more or less completely surrounded by the chorionic villi.

Carneous mole (syn: blood mole, fleshy mole, tuberous mole) it is the pathological variant of missed abortion affecting the fetus before 12 weeks. Small repeated haemorrage in the choriodecidual space disrupt the villi from its attachments. The bleeding is slight so it does not cause rupture of the deciduas capsularis. The clotted blood with the contained ovum is known as a blood mole. By this time, the ovum becomes dead and is either completely aborted or remains as a rudimentary structure. Gradually the fluid portion of the blood surrounding the ovum gets aborted and the wall becomes fleshy, hence the term fleshy or carneous male. The wall looks dark red in, colour, laminated appearance showing the presence of degenerated villi in the blood clot on microscopic examination. The amniotic cavity lined by the smooth amnion is thrown into irregular bulges by unequal distribution of laminated organized clotted blood outside it, resulting in formation of what is known as tuberous mole.

Clinical features: the patient usually presents with the features of threatened abortion followed by:

  • Persistence of brownish vaginal discharge.
  • Subsidence of pregnancy symptoms.
  • Retrogression of breast changes.
  • Cessation of uterine growth which in fact smaller in size.
  • Non-audibility of the fetal heart sounds even with Doppler.
  • Cervix feels firm.
  • Immunological test becomes negative.
  • Radiological evidence of collapsed fetal skeleton if the pregnancy has proceeded to over 16 weeks.
  • Ultrasonography reveals an empty sac early in the pregnancy or the absence of fetal motion or fetal heart movement later in the pregnancy.

Complications:

  • psychological upset
  • infection
  • Blood coagulation disorders –if the fetus is retained for more than 4 weeks ( as occur in the 10-20% cases) there is a possibility of defibrination from ‘silent’ disseminated intravascular coagulopathy (D.I.C).  it is due to gradual absorption of thromboplastin, liberated from the dead placenta and deciduas, in to the maternal circulation.
  • During labour- uterine inertia, retained placenta and postpartum haemorrage.

Management:

  • Uterus is less than 12 weeks: vaginal evacuation can be carried out without delay. This can be effectively done by suction evacuation or slow dilatation of the cervix by laminaria tent followed by dilation and evacuation (D&E) of the uterus under general anaesthesia. The risk of damage to the uterine walls and brisk haemorrage during the operation should be kept in mind.
  • Uterus more than  12 weeks: induction is done by the following methods:

Oxytocin to start with 10-20 units of oxytocin in 500ml of 5% dextrose saline is administered in drip with  30 drops per minute. If fails, escalating dose of oxytocin to the maximum of 100 units, in a pint of 5% dextrose saline at a drip rate of 30 drops per minute, may be used with precaution.

Prostaglandins: prostaglandin is more effective than oxytocin in such cases. The following procedures may be employed:

(a)  Intramuscular administration of 15 methyl PGF2 (carboprost tromethamine) 250 at three hourly intervals for a maximum of 10 such.

(b)  Prostaglandin E1 analogue (gemiprost) 1 mg pessary is inserted into the posterior vaginal fornix every 3 hours for a maximum 5 such.