Fetal death in utero (FDIU), also known as intrauterine death (IUD), is the term used when the death of a fetus occurs after the 20^th week of pregnancy. Prior to this, it is considered a miscarriage.

Terminology

IUD is often also used as an abbreviation for an intrauterine contraceptive device. However, this shortening is disliked by some specialists in view of its use as an abbreviation for intrauterine death. Therefore for many the preferred abbreviation for an intrauterine contraceptive device is IUCD. 

The spelling fetus and fetal are the preferred spellings in the medical world, regardless of location. They are used by virtually all biomedical journals. Therefore they are also the preferred spelling on Radiopaedia and we never use the spelling foetus or foetal (see fetus vs foetus for more detail) ³.

Epidemiology

1% of normal, uncomplicated pregnancies end in fetal death. In ~15% of fetal death in utero, no cause is identified.

Pathology

Etiology

Maternal 

• gestational hypertension

• blood group incompatibility

• metabolic disorders

• intrauterine infections

Fetal

• major anomalies

• umbilical cord complications (looping, knotting, twisting, straight cord)

Placental

Placental pathologies are thought to represent the largest category of cause of intrauterine death ⁴.

• chronic placental insufficiency

• placental abruption

• chorioamnionitis

Radiographic features

Ultrasound

• absent fetal heartbeat

• absent fetal movements

• occasional findings

  • overlapping of skull bones (Spalding sign)

  • gross distortion of fetal anatomy (maceration)

  • soft tissue edema: skin >5 mm

  • echogenic amniotic fluid (fetal demise fragments)

• uncommon findings

  • thrombus in fetal heart

  • gas shadow in fetal heart (Robert sign)​

See also

• failed early pregnancy