Faculty Bibliography

OBJECTIVE: In an effort to elucidate possible causes of preterm labor, we undertook a prospective study of 50 patients consecutively admitted with intact membranes and preterm labor who eventually had a preterm delivery despite the use of tocolysis. STUDY DESIGN: A comprehensive evaluation plan was instituted. This included a detailed history and physical examination, targeted ultrasonography, amniocentesis for Gram stain, culture, and glucose determination, laboratory analysis for infection (complete blood cell count, urinalysis, and cervical and urine cultures) and for antiphospholipid antibody syndrome (antinuclear antibody, lupus anticoagulant, anticardiolipin antibody), pathologic examination of the placenta, and a urine toxicology screen. RESULTS: The following groups of possible causes of preterm labor were identified: (1) faulty placentation, 50% (25/50); (2) intrauterine infection 38% (19/50); (3) immunologic factors, 30% (15/50); (4) cervical incompetence, 16% (8/50); (5) uterine factors, 14% (7/50); (6) maternal factors 10% (5/50); (7) trauma and surgery, 8% (4/50); (8) fetal anomalies, 6% (3/50); and (9) idiopathic conditions, 4% (2/50). Among the 50 patients two or more possible causes were identified in 58% (29/50). CONCLUSION: We suggest that an exhaustive evaluation plan can identify possible causes in the majority (96%) of cases of 'idiopathic' preterm labor that result in preterm delivery

OBJECTIVE:The purpose of this study was to determine if gap junctions are a necessary component of the human laboring uterus and if their presence in myometrium is a prerequisite for both term and preterm labor. STUDY DESIGN/METHODS:We obtained 27 human myometrial samples at cesarean section or nongravid hysterectomy. Gap junction formation was analyzed in a blind fashion by freeze fracture and indirect immunofluorescence. Six samples were obtained from term patients with no labor, six from term patients in labor, six from preterm patients with no labor, six from patients in preterm labor, and three from nongravid hysterectomy specimens. RESULTS:Gap junction structures were identified in the human myometrium of patients in term and in preterm labor but not in the other patient samples. In addition, evidence was obtained for the expression of (alpha 1) gap junction ribonucleic acid and (alpha 1) gap junction protein in term samples of human myometrium. CONCLUSION/CONCLUSIONS:Gap junctions are a necessary component of the human myometrium during term and preterm labor. The formation of gap junctions may be a final common event for the development of labor, and inhibition of gap junction activity could be a novel approach for the treatment of preterm labor.

Fetal/neonate kidneys obtained at the time of autopsy were utilized to determine a suitable needle biopsy gauge to obtain renal parenchyma for histologic evaluation. Twenty-one fresh kidney specimens from 11 fetuses/neonates between 16-40 weeks gestation were used to obtain needle biopsies using 20-, 18-, 16-, and 14-gauge biopsy catheters. The specimens were graded according to the presence of normal histologic features of renal parenchyma. Seventy-five renal biopsies were obtained. The biopsy histology was interpreted using a grading system based on the presence of normal features of the renal parenchyma. Sixty-three (84%) of the samples were graded histologically as adequate (cortex or medulla present). Samples with both cortex and medullary structures present (completely adequate) were obtained in 39/63 (62%) of these adequate biopsies. The 14- and 16-gauge biopsy catheters gave the best results, respectively yielding 79 and 69% completely adequate biopsies. This is in contrast to the 20- and 18-gauge catheters that respectively yielded 35 and 25% completely adequate biopsies. Our initial results indicate that adequate kidney biopsies can be obtained. However, the current technique is associated with core sample disruption when the smaller gauge catheters are used. This could account for the low rate of completely adequate samples with the smaller gauge catheters. A different sampling technique is needed to overcome sample disruption, to determine the smallest catheter gauge that will yield a suitable tissue sample for histologic evaluation.

OBJECTIVE:To test the hypothesis that small ears have diagnostic value in detecting second-trimester aneuploid fetuses by ultrasound. METHODS:We prospectively studied 452 patients with singleton pregnancies undergoing ultrasound examination for genetic amniocentesis at 14-25 weeks and an additional 30 singleton pregnancies at 20-25 weeks with a negative anomaly screen. Standard fetal biometry measurements were obtained, including ear length (from helix to end of lobe). RESULTS:Of these patients, 424 (88%) had ear measurements obtained, and a nomogram for ear length by gestational age was compiled. The relationship between ear length and gestational age was linear across the second trimester (r = 0.84, P < .001). Fourteen fetuses had aneuploidy by amniocentesis, of whom ten had ear lengths at or below the tenth percentile. The sensitivity was 71% and the specificity 92% (377 of 410). Positive and negative predictive values were 23% (ten of 43) and 99% (377 of 381), respectively. CONCLUSION/CONCLUSIONS:Fetal ear length may be useful in identifying aneuploid fetuses sonographically during the second trimester.

OBJECTIVES/OBJECTIVE:Transverse cerebellar diameter measurements have been established for singleton but not twin pregnancies. In singleton pregnancies controversy exists on whether cerebellar growth is affected by intrauterine growth retardation. We undertook this retrospective study in twin pregnancies to establish a nomogram for the transverse cerebellar diameter in twins and to assess the effect of growth retardation on this measurement. STUDY DESIGN/METHODS:A retrospective review was performed on 171 patients with twin pregnancies with reliable dating from 15 to 36 weeks' gestation who had been referred to our antenatal evaluation unit for routine ultrasonographic examination. Of the 342 fetuses, 322 were available for analysis and establishment of a nomogram for the transverse cerebellar diameter. Twenty-four twin, growth-retarded fetuses were analyzed separately. RESULTS:The transverse cerebellar diameter increased linearly with gestational age (r = 0.94, p < 0.001). Fifteen (63%) of the growth-retarded fetuses had a transverse cerebellar diameter of < or = 5th percentile for gestational age. CONCLUSION/CONCLUSIONS:We suggest that intrauterine growth retardation may affect cerebellar growth in twins.

The perinatal mortality rate of twins is four to 11 times higher than that of singletons, and twins are widely reported to have more morbidity than singletons, mainly because of a higher preterm birth rate. However, it is not clear that live-born preterm birth rate. However, it is not clear that live-born preterm twins suffer greater morbidity than comparable singletons. In fact, twins have been reported to develop pulmonary maturity earlier than singletons, which might result in decreased morbidity relative to comparable preterm singletons. We conducted this retrospective review of 496 consecutive singleton and 104 twin infants weighing 500-1499 g and born alive at 24-31 weeks' gestation to determine whether pre-discharge survival and morbidity in very low birth weight (VLBW) twin infants were greater than those of comparable singletons. The mean (+/- standard deviation) gestational age of the singletons was 27.5 +/- 2.0 weeks and of the twins 27.6 +/- 2.0 weeks. There were no differences in mean gestational age, gestational age distribution, mean birth weight, birth weight distribution, gender, or maternal race between the two groups. The pre-discharge survival rate for twins (77%) was not significantly different than that of singletons (82%). There were no differences between twins and singletons in the incidences of neonatal respiratory distress syndrome (63 versus 71%), pulmonary interstitial emphysema (14 versus 16%), patent ductus arteriosus (28 versus 29%), necrotizing enterocolitis (3 versus 5%), intraventricular hemorrhage (11 versus 16%), and retinopathy of prematurity (11 versus 18%). The incidence of bronchopulmonary dysplasia was significantly less in twins (27 versus 46%; P = .001).(ABSTRACT TRUNCATED AT 250 WORDS)

In summarizing the published data on the use of amniocentesis and fetal biophysical assessment in managing patients with PROM the following conclusions may be drawn: 1. Both amniocentesis and fetal biophysical assessment are reasonably good methods to predict the fetus who is doing well and could therefore safely remain in utero, as well as the fetus who is at high risk for developing sepsis and therefore in need of delivery. 2. Consideration of routine transabdominal amniocentesis for Gram stain and cultures in patients with PROM is reasonable. Measurements of glucose levels, esterase activity, or cytokines are only investigational, and their use in patient management cannot be advocated at this time. 3. Although there are no prospective controlled randomized trials to prove improved pregnancy outcome by the use of either amniocentesis or frequent biophysical assessment, nonrandomized comparative trials as well as trials using historic controls suggest that the use of either or both techniques in combination may be beneficial in managing PROM.

The present study of 466 consecutive liveborn preterm singleton deliveries included 238 cases of spontaneous preterm labor and delivery, 175 cases with premature rupture of membranes, 13 cases of nonhypertensive abruption, 18 cases of preeclampsia, and 22 cases of placenta previa. Placental infarction, chronic villitis, and decidual pathologic processes showed different associations with fetal growth, depending on the clinical circumstances. Placental infarction was associated with decreased growth in all groups except placenta previa; in cases of placenta previa, placental infarction was associated with heavier infants. Chronic villitis was related to decreased growth in spontaneous rupture of membranes and preterm labor cases but was related to increased growth in cases of preeclampsia

Placental examination was carried out in 128 consecutive cases of idiopathic intrauterine growth retardation (IUGR) at term and the findings were compared with those of 179 gestational age-matched cases with normal growth. Mean pregnancy weight and mean maternal weight gain during pregnancy of IUGR cases were both significantly lower than for non-IUGR cases. There was a higher frequency of a history of previous growth-retarded infants between IUGR cases (18 of 128, or 14%) compared with non-IUGR cases (7 of 179, or 3.9%). The studied placental lesions were placental infarction, chronic villitis, hemorrhagic endovasculitis, and placental vascular thromboses. One or more of these lesions were present in 71 of 128 (55%) of IUGR cases, and 58/179 (32%) of non-IUGR cases. Thirty-eight of 72 (53%) cases with chronic villitis were IUGR (30% of all IUGR cases). Thirty-one of 49 cases (63%) with placental infarction were IUGR cases (24% of all IUGR cases). Nineteen of 32 cases (59%) with hemorrhagic endovasculitis were IUGR cases (15% of all IUGR cases). Twelve of 17 cases (71% with placental vascular thromboses were IUGR (9% of all IUGR cases). Relationships of all placental lesions to IUGR were independent of each other. IUGR infants more frequently had multiple types of lesions in their placentas. Chronic villitis and hemorrhagic endovasculitis tended to occur in the same placentas. There were no significant relationships between maternal characteristics and placental lesions, except for an association between low pregravid weight and increased incidence of placental infarction. Decreased birth length was associated only with placental infarction (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

One hundred fifty-eight cases are reported of fetal cardiocentesis during the second trimester for the prenatal diagnosis of hemoglobinopathies. In all cases, fetal blood sampling by funipuncture was technically impossible or unsuccessful. There were nine fetal deaths possibly related to the procedure, for a total fetal loss rate of 6.5%. If one fetal loss that occurred 46 days after the procedure is excluded, the total procedure-related fetal loss rate is 5.6%. No cases of maternal chorioamnionitis, fetal cardiac trauma, or hemopericardium were encountered among the living infants. We conclude that cardiocentesis should be offered in highly selective cases when funipuncture is not technically feasible. In experienced hands, the procedure has a fetal loss rate of 6.5% with no morbidity among the survivors.