Elevated alpha-fetoprotein and a normal fetal sonogram: association with placental abnormalities

Subchorionic Hemorrhage in the Second and Third Trimesters of Pregnancy: A Review

Importance

Subchorionic hemorrhage (SCH) in the second and third trimesters of pregnancy can be associated with maternal morbidity and fetal morbidity/mortality. Management of SCH in the second or third trimesters can be complicated, especially in the setting of a large SCH that requires hospitalization and blood transfusion.

Objective

The aim of this review is to describe SCH in second and third trimesters, risk factors, diagnosis, maternal and fetal outcomes, and management of this uncommon pregnancy complication.

Evidence Acquisition

A PubMed, Web of Science, and CINAHL search was undertaken with no limitations on the number of years searched.

Results

There were 123 abstracts and/or articles reviewed, with 48 articles being the basis of review. The only known risk factors for SCH are maternal factor deficiency and anticoagulation therapy. The diagnosis is usually made by ultrasound imaging. Subchorionic hemorrhage in second and third trimesters has been associated with several adverse fetal outcomes including preterm birth, preterm prelabor rupture of membranes, fetal growth restriction, fetal demise, and neonatal pulmonary morbidity. There is no proven treatment for SCH, although there are several investigational therapies reported.

Conclusions

Subchorionic hemorrhage can be complex and difficult to manage in the second and third trimesters. There are no recommendations or guidelines for management; however, serial growth ultrasounds, umbilical artery Doppler studies, and antenatal fetal testing should be considered particularly if the SCH is large or treatment requires a maternal blood transfusion.

Relevance

Subchorionic hemorrhage in the second and third trimester is associated with poor fetal outcomes and maternal morbidity, especially if the SCH is significant.

Association of maternal serum α-fetoprotein with persistent placenta previa

OBJECTIVE

To evaluate the relationship between maternal serum alpha-fetoprotein (MSAFP) and the risk of persistent placenta previa.

METHODS

We conducted a retrospective cohort study of singleton pregnancies with sonographic evidence of placenta previa at 15-20 weeks' gestation, between October 1991 and August 2000. Only pregnancies with MSAFP determination at 15-20 weeks' gestation and non-anomalous live-born infants > or =24 weeks' gestation were included. Pregnancies in which Cesarean delivery was performed for placenta previa were considered persistent; this was the primary outcome.

RESULTS

Of 275 women with previa at 15-20 weeks' gestation, 33 (12%) had previa at delivery. Trend analysis revealed a greater likelihood of persistent previa with increasing MSAFP values (p=0.01). Mid-trimester MSAFP <1 multiple of the median (MoM) was associated with a decreased incidence of persistence of 4%, significantly less than the risk at > or =1 MoM (16%; p=0.01).

CONCLUSIONS

There is an association between increasing MSAFP values and greater likelihood of persistent placenta previa. An MSAFP value <1 MoM is associated with a reduction in the risk of persistence of previa to delivery.

A case of maternal reaction due to fetomaternal transfusion

We present here a case of maternal reaction to fetomaternal transfusion complicated by subchorionic hemorrhage. A 40-year-old woman, gravida 2, para 0, was admitted to our hospital at 25 weeks' gestation because of high blood pressure. On the morning of 32 weeks and 2 days' gestation, she developed sudden onset nausea, dyspnea and regular uterine contractions. Blood pressure was 80/50 mmHg and pulse was 110 beats/minute. At this time, her WBC, hemoglobin and platelets were decreased significantly. Two hours after onset, the patient's condition improved spontaneously. Increased serum alpha-fetoprotein level (3.0 multiple of median) was observed. She was suggested to be a case of acute fetomaternal transfusion.

Pregnancy outcomes and community health: the POUCH study of preterm delivery

In light of the social/ethnic disparity in preterm delivery (PTD) rates, the Pregnancy Outcomes and Community Health (POUCH) Study takes a broad view of the determinants of PTD by attempting to link underlying biological and psychosocial factors. The relationships between placental pathology, maternal biomarkers, and antecedent psychosocial factors are evaluated in three hypothesised pathways of PTD - one characterised primarily by infection, one by maternal vascular disease, and one by premature elevations in corticotropin releasing hormone in the absence of histological evidence of placental pathology. Within each pathway, an emphasis is placed on understanding the roles of stress and of maternal serum alpha-fetoprotein, an early biomarker associated with PTD. The POUCH Study enrolls pregnant women from five Michigan communities. Information about these women and their environments is gathered through detailed interviews and collection of biological samples including hair, urine, saliva, blood, vaginal fluid, and vaginal smear at 15-26 weeks of gestation. We have chosen to focus on the second trimester--a time when pathological processes may have evolved to a detectable stage, but generally before the onset of biological changes that accompany labour. This focus is consistent with the long-range goal of early detection/intervention and prevention of PTD.

Sonography of the placenta with emphasis on pathological correlation

The placenta is a most interesting but unfortunately often ignored and misunderstood organ. Included in its many functions are fetal oxygenation and nutrition as well as a myriad of endocrinological contributions and protein synthesis. The sonologist is strongly encouraged to study this amazing structure with ultrasound because significant pathology afflicts the placenta, often before affecting the fetus. Placental abnormalities, therefore, can be an "early warning system" for fetal problems. Recognition of clinically important lesions (abruption, accreta) as well as important anatomical variants (intervillous thrombosis, septal cyst) is crucial for the physician who performs and interprets prenatal ultrasound. This article discusses the common abnormalities of the placenta and highlights some correlative pathological processes, which will serve to enhance the reader's understanding of sonographic findings. A practical approach is presented with respect to assessment of the hypoechoic lesion, placental infarction, thick placenta, placenta previa, abruption, placenta accreta, and placental tumors.

Ultrasonographic investigation of placental morphologic characteristics and size during the second trimester of pregnancy

OBJECTIVE

The aim of the study was to establish the incidence of abnormal placental ultrasonographic findings in an unselected obstetric population and determine the usefulness of simple measurements of placental size. In addition, the relationship between these findings, uterine artery Doppler measurements, maternal serum alpha-fetoprotein levels, and subsequent pregnancy outcome was explored.

STUDY DESIGN

A prospective, cross-sectional study of 210 women recruited at the time of routine ultrasonographic scan between 16 and 28 weeks' gestation was performed. Placental ultrasonographic investigations included measurements of thickness, circumference, and volume and morphologic studies. Uterine Doppler and maternal serum alpha-fetoprotein measurements were performed at the same time.

RESULTS

At delivery 25 fetuses were small for gestational age, in association with hypertension in 11; 14 were delivered prematurely but were appropriately grown, and three were macrosomic. Significant correlations were found in uncomplicated pregnancies (n = 168) between gestational age and placental thickness, circumference, and volume and also between fetal abdominal and placental circumferences. Large sonolucent lakes were found with a similar incidence in both complicated and uncomplicated pregnancies. Jelly-like placental appearance was seen in 12 of the 17 cases complicated by hypertension, 11 of which also had abnormal uterine Doppler features and elevated maternal serum alpha-fetoprotein levels.

CONCLUSIONS

This study shows an association between abnormal placental development, ultrasonographic appearances, and subsequent abnormal fetal growth or hypertensive disorders of pregnancy. The interrelationships demonstrated between the different techniques suggest that a combination of placental thickness and morphologic characteristics, uterine Doppler analysis, and evaluation of maternal serum alpha-fetoprotein level may allow more efficient screening for these complications than is currently possible using any single method.

Elevated maternal serum alpha-fetoprotein levels and midtrimester placental abnormalities in relation to subsequent adverse pregnancy outcomes

OBJECTIVE

Unexplained elevations of maternal serum alpha-fetoprotein levels in the second trimester of pregnancy are associated with adverse pregnancy outcomes, including intrauterine growth retardation, preterm delivery, preeclampsia, and abruptio placentae. In addition, elevations of maternal serum alpha-fetoprotein have been associated with placental lesions detected during second-trimester ultrasonographic evaluations. We examined the relationship between adverse pregnancy outcomes and unexplained elevations of maternal serum alpha-fetoprotein and placental abnormalities in the second trimester of pregnancy.

STUDY DESIGN

During the period from January 1989 to March 1991 we conducted a cohort study of 201 women with an elevated maternal serum alpha-fetoprotein (> or = 2.0 multiples of the median) and a second-trimester ultrasonographic evaluation at Swedish Hospital Medical Center and 211 women with normal maternal serum alpha-fetoprotein levels who had also undergone ultrasonographic evaluation at the same institution. All women in this investigation had singleton pregnancies without fetal anomalies.

RESULTS

Elevated maternal serum alpha-fetoprotein was associated with the following adverse pregnancy outcomes: low birth weight (adjusted risk ratio 3.7), preterm delivery (adjusted risk ratio 3.6), intrauterine growth retardation (adjusted risk ratio 4.0), preeclampsia (adjusted risk ratio 3.8) and abruptio placentae (adjusted risk ratio 4.8). Placental abnormalities detected during second-trimester ultrasonographic evaluations were also associated with adverse pregnancy outcomes: low birth weight (adjusted risk ratio 2.0), preterm delivery (adjusted risk ratio 2.3), intrauterine growth retardation (adjusted risk ratio 1.4), and abruptio placentae (adjusted risk ratio 9.0). A joint positive history of second-trimester elevations of maternal serum alpha-fetoprotein and placental abnormalities was more strongly associated with the following adverse infant outcomes: low birth weight (adjusted risk ratio 6.9), preterm delivery (adjusted risk ratio 5.6), and intrauterine growth retardation (adjusted risk ratio 5.3).

CONCLUSIONS

Unexplained elevated levels of maternal serum alpha-fetoprotein and placental abnormalities detected in the second trimester of pregnancy are associated with particularly poor pregnancy outcome. Careful examination for placental abnormalities should be part of the evaluation of elevated maternal serum alpha-fetoprotein.

The roles of ultrasonography and amniocentesis in evaluation of elevated maternal serum alpha-fetoprotein

A total of 681 pregnant women were referred for evaluation of elevated maternal serum alpha-fetoprotein levels. Ultrasonographic examination yielded an explanation for the elevation of maternal serum alpha-fetoprotein in 42% of patients. Diagnoses made by ultrasonography included incorrect fetal dating, multiple gestation, fetal death, open neural tube defect, abdominal wall defect, placental abnormalities, cystic hygroma, renal anomalies, and oligohydramnios. Optimal prenatal diagnosis of fetal anomalies also requires the use of amniocentesis in many patients. Amniocentesis may be obviated if fetal dating is incorrect, if an unsuspected multiple gestation is discovered, or if there is a clear anomaly and the parents do not desire genetic counseling based on karyotype information. If the fetus appears normal, the ultrasonographic results are equivocal, or the parents desire more detailed genetic counseling when an anomaly is found by ultrasonography, then amniocentesis should be performed. Thirteen abnormalities were diagnosed by amniocentesis alone in this group.

Ultrasonographic diagnosis of a large placental intervillous thrombosis associated with elevated maternal serum alpha-fetoprotein level

A placental lesion associated with elevated maternal serum alpha-fetoprotein level and a positive Kleihauer-Betke test is reported. Serial ultrasonograms showed a progressive increase in the echogenicity of the lesion that corresponded to a large intervillous thrombosis after delivery. This case illustrates the importance of detailed ultrasonographic and pathologic placental investigations in pregnancies with unexplained elevated levels of alpha-fetoprotein.