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|What Is Intrauterine Fetal Death?
In addition to cases in which a fetus dies during delivery as a result of asphyxia (oxygen deprivation if the umbilical cord becomes twisted) or difficult labor, others can die in utero before labor starts. This is usually followed by expulsion of the fetus from the uterus within a few days. However, in rare instances the dead fetus is not expelled from the uterus at once, but is retained for several weeks. Fetal death refers to the spontaneous death of a fetus at any time during pregnancy, although the term is often used interchangeably with ‘stillbirth’. A stillbirth is a death that occurs after 20 weeks of gestation.
This differentiation is important for statistical purposes because in many states an intrauterine fetal death does not have to be reported at less than 20 weeks or 350 gram birth weight (it varies from state to state). Before this, it is categorized as a miscarriage. However there is some overlap, a late miscarriage (called a spontaneous abortion) is the loss of a fetus after week 6 up until week 24. The stillbirth rate in America is about 1 in every 155 births, that amounts to about 26,000 stillbirths a year.
What Causes Intrauterine Fetal Death?
The cause of a large percentage of stillbirths is never discovered, even where extensive testing and autopsy after the event is carried out. Where the cause is discovered it tends to be one of the following:
1. High blood pressure during pregnancy, including preeclampsia.
2. Chronic kidney disease in pregnancy.
3. Fetal hypoxia (lack of oxygen) produced by reduction in the maternal blood supply to the placenta because of spasms, and sometimes thrombosis (blood clots) in the placenta vessels. Added to this there may be separation of the placenta (placenta abruption) or extensive clotting of maternal blood around the chorionic villi of the placenta.
4. Diabetes (including gestational diabetes): If the mother’s diabetes is poorly controlled fetal death in utero often occurs.
5. Postmaturity: Although, an uncommon cause of fetal death before labor.
6. Umbilical cord accidents: True knots in the cord or constriction of the cord round a limb are very rare causes of fetal death.
7. Hemolytic disease: Where the blood cells of the fetus are attacked by the mothers’ antibodies.
Unexplained placental insufficiency. Apart from the cases of hypertension and renal disease already mentioned, in a few patients unexplained placental insufficiency occurs in successive pregnancies. Further investigation may reveal anticardiolipin antibodies in maternal blood. In such cases the fetus does not grow at the normal rate and intrauterine death may occur. The placenta is found to be small but appears to be normal in other respects. In the absence of any explanation for some cases, the only advice which can be offered is intensive fetal monitoring and rest of the mother in bed during most of the pregnancy, with the hope that this will increase the uterine blood flow. Delivery before the time at which previous deaths occurred is wise, either by labor induction or caesarean section. Fetal monitoring tests can give some guidance in deciding when to advise delivery.
9. Fetal malformation (birth defects): With severe malformation intrauterine death sometimes occurs.
10. Infective diseases: Any disease that causes high fever in pregnancy and toxic illness can cause fetal death.
11. Untreated syphilis and rare fetal infection with herpes virus or other viruses may cause death. Severe rubella is sometimes fatal to the fetus.
Symptoms and Diagnosis
The mother may notice less movement in the fetus for several days, and her breasts may diminish in size. In cases of hypertension the blood pressure sometimes falls. The following signs may be found:
After the 24th week the fetal heart sounds can normally be heard with a stethoscope; failure to hear them will be strong presumptive evidence of fetal death. An ultrasound scan can detect the fetal heart beat as early as the 8th week of pregnancy, and if a careful and repeated search shows no evidence of cardiac activity, fetal death is almost certain.
The uterus may be found to be smaller than the duration of pregnancy would warrant. A more accurate sign is to note how much the uterus grows during a period of observation. For this the bladder must be empty and the level of the fundus accurately noted during an ultrasound. The patient is examined week by week. If no uterine enlargement is observed in 4 weeks this strongly suggests that the fetus is dead. In some cases the uterus not only ceases to grow but gets smaller because of absorption of the amniotic fluid.
Sometimes secretion of colostrum (pre-breast milk) from the breasts occurs a few days after the death of the fetus.
Ultrasonic examination will show overlapping and misalignment of the skull bones (Spalding's sign) and occasionally the presence of gas in the fetal heart and blood vessels (Roberts' sign). Spalding's sign is not usually present until a week after fetal death, but gas formation may be seen after only 2 days. Blood tests for pregnancy are usually negative within a week after the death of the fetus, but sometimes a weakly positive test persists for a time, presumably because some placenta tissue is still active. The excretion of estriol (a type of estrogen produced by an active placenta) in the mother's urine falls sharply.
As you can see, it is often difficult to diagnose fetal death from a single clinical examination of the patient, and urgent regular sonography is usually requested. Doctor’s tend not to place too much importance on the mother’s statements about fetal movements as it may be wishful thinking.
In the majority of cases labor follows death of the fetus within a few days, but sometimes labor does not occur for several weeks. In these cases there is no urgent call for intervention, but after 2 weeks there is a small risk of dangerous blood clots forming, so intervention may then be recommended. If the patient becomes greatly distressed at any point, labor can be induced but artificial rupturing of the membranes (AROM) is unwise because of the risk of infection from growth of bacteria in the dead placental and fetal tissues if labor does not follow quickly.
Instead labor will be induced with the hormone oxytocin (Pitocin) which is injected through a vein. Oxytocin stimulates uterine contractions. A cesarean section is not generally needed unless delivery complications occur. Women who undergo this experience should have follow-up, bereavement counseling and, where appropriate, genetic counseling.