Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (278 page)

No laboratory tests are available to predict fetal loss. Screens for genetic abnormalities may be helpful to predict poor outcome. Other risks include advanced maternal age, obesity, smoking, multiple gestations, maternal hypertension, diabetes and collagen vascular disease, and a past history of fetal loss.

The diagnosis of fetal death is usually made by the mother noting decreased fetal movements and uterine bleeding or contractions. The diagnosis is confirmed by ultrasound examination.

Reference

1.  Stillbirth Collaborative Research Network Writing Group. Causes of death among stillbirths.
JAMA.
2011;306:2459.

POSTTERM PREGNANCY

   Definition

A prolonged or postterm pregnancy is defined as one lasting >294 days or 42 weeks of gestation. The etiology is unknown for most cases and rarely may be due to abnormal fetal production of hormones that are involved in parturition.

   Clinical Presentation

Patients at risk include patients with previous postterm pregnancy, nulliparity, male fetus, maternal obesity, advanced maternal age, and race (Caucasians are at a greater risk).

   Laboratory Findings

   A progressively falling rather than a rising serum estriol (E3) is usually found.

   Amniotic fluid L/S ratio is not useful.

MULTIPLE GESTATION PREGNANCY

   Definition

Pregnancy with more than one fetus.

   Clinical Presentation

Multiple gestations are increasing due to increased maternal age at childbirth and the increased use of fertility drugs such as clomiphene citrate and gonadotropins and in vitro fertilization. Thirty-one percent of the cases are monozygotic (see eBook Figure 8-15)
¹
. Risks posed by multiple gestations include preterm birth, fetal growth restriction, and increased mortality due to obstetric complications and congenital anomalies. Preeclampsia is also increased.

   Laboratory Findings

In women with multiple gestations, estradiol, FSH, and luteinizing hormone may be elevated. The hCG may be increased, with increased maternal serum AFP.

Reference

1.  Cameron AH, Edwards JH, Derom R, et al. The value of twin surveys in the study of malformations.
Eur J Obstet Gynecol Reprod Biol.
1983;14:347.

PLACENTAE ABRUPTIO AND PREVIA

Placenta abruptio
is the premature separation of normally implanted placenta after the 20th week of gestation. It causes hemorrhage and 15% of third-trimester stillbirths. There are no diagnostic laboratory findings. Laboratory findings are hypovolemic shock, acute renal failure, and DIC (it is the most common cause of DIC in pregnancy).

Placenta previa
is the abnormal implantation of the placenta into the lower uterine segment. It may cover part (partial) or all (complete) of the internal os resulting in painless vaginal bleeding and increases risk for fetal demise. Laboratory findings are due to blood loss. Maternal HCT should be maintained at ≥35%.

PRETERM DELIVERY

   Definition

Preterm delivery is defined as a gestational age <37 weeks from the LMP; however, birth prior to 38 weeks also has increased morbidity and mortality. Prematurity may also be defined as low birth weight infants (<2,500 g), very low birth weight (<1,500 g), and extremely low birth weight (<1,000 g). Preterm birth may be due to infection, placental abruption or hemorrhage, pathologic uterine distention, or stress in the mother or fetus. It is more likely to occur in women under 20 years of age or over 35 years of age. Patients present with uterine contractions and vaginal discharge (mucus or bloody show). The diagnosis is made on physical examination with cervical dilation or defacement, regular contractions, bleeding, and ruptured membranes.

   Laboratory Findings