Ilan Timor-Tritsch

A close look at early embryonic development with the high-frequency transvaginal transducer

Transabdominal sonography has been, for the past two decades, used as an effective diagnostic and research tool in obstetrics. It is predominantly used in the second and third trimesters of gestation. Its use in the first trimester is relatively limited and mostly diagnostic in nature. The introduction of the higher frequency transvaginal transducer probe, with its higher resolution of the images, opens new possibilities to study early gestation. We studied embryonic development in 38 well-dated and normal pregnancies. A well-defined intrauterine gestational sac could be seen at 4 weeks and 1 to 4 days of menstrual age. The beta-subunit of human chorionic gonadotropin level at this time was 450 to 750 mlU/ml. Structures such as the yolk sac, membranes, ventricular system in the brain, musculoskeletal system, and cord were described and illustrated. Textbooks and atlases were used for comparative purposes. High-resolution transvaginal sonography will facilitate first-trimester perinatology.

Efficacy of second-trimester selective termination for fetal abnormalities: International collaborative experience among the world's largest centers

OBJECTIVEnOur goal was to develop the most comprehensive database possible to counsel patients about selective termination for fetal abnormalities, because no one center has sufficient data to assess much more than crude loss rates.nnnSTUDY DESIGNnA total of 183 completed cases of selective termination from 9 centers in 4 countries were combined (169 twins, 11 triplets, 3 quadruplets). Variables included indications, methods, (potassium chloride, exsanguination, air embolus), gestational age at procedure, pregnancies lost (< or = 24 weeks), gestational age at delivery, and neonatal outcome.nnnRESULTSnIndications for selective termination were 96 chromosomal, 76 structural, and 11 mendelian. Selective termination was technically successful in 100% of cases. In 23 of 183 (12.6%) miscarriage occurred before 24 weeks; 2 of 37 (5.4%) occurred when the procedure done at < or = 16 weeks and 21 of 146 (14.4%) when it was done thereafter. Air embolization had a higher loss rate: 10 of 24 (41.7%) compared with 13 of 156 (8.3%) by potassium chloride (chi 2 = 117, p < 0.0001). Three cases of selective termination performed in monochorionic pregnancies all resulted in pregnancy loss. Among 183 potentially viable deliveries, 7 occurred before 28 weeks, 19 at 29 to 32 weeks, 41 at 33 to 36 weeks, and 93 at > or = 37 weeks. Gestational age at delivery was not influenced by the technique used or the indication but was negatively correlated with gestational age at the time of selective termination. No coagulopathy or ischemic damage was observed in survivors. There was no maternal morbidity.nnnCONCLUSIONSn(1) Selective termination in experienced hands for a dizygotic abnormal twin is safe and effective when done with potassium chloride. A total of 83.8% of viable deliveries occurred after 33 weeks and only 4.3% at 25 to 28 weeks. (2) Gestational age at the procedure correlated positively with loss rate and inversely with gestational age at delivery; this emphasizes the need for early diagnosis in multifetal pregnancies. (3) Coagulopathy tests are probably unnecessary.

Can a “snapshot” sagittal view of the cervix by transvaginal ultrasonography predict active preterm labor?

OBJECTIVEnOur purpose was to test the hypothesis that wedging of the cervical internal os determined by transvaginal ultrasonography is associated with premature labor and delivery.nnnSTUDY DESIGNnSeventy patients admitted to the hospital for threatened preterm labor were evaluated by transvaginal ultrasonography before institution of therapy. Bivariate and logistic regression analyses were performed to determine the variables that made a significant contribution to the prediction of preterm delivery.nnnRESULTSnPreterm delivery was significantly associated with the presence of cervical wedging, as noted on cervical scan, and with short cervical length. A history of previous preterm delivery was of marginal significance as a predictor of preterm delivery (p=0.09). Preterm delivery was not significantly correlated with age, previous voluntary termination of pregnancy, gestational age at the time of study, previous normal spontaneous vaginal delivery, or tocolytic therapy. Use of wedging as a diagnostic test for the prediction of preterm delivery yielded a sensitivity of 100% a specificity of 74.5%, a positive predictive value of 59.4%, and a negative predictive value of 100%.nnnCONCLUSIONnThe presence of wedging and shorter cervical length was suggestive of true preterm labor requiring aggressive management. A transvaginal ultrasonographic snapshot view of the cervix seems to be a more reliable method to evaluate the cervix in patients with threatened premature labor than are uterine contractions alone.

Dating the early pregnancy by sequential appearance of embryonic structures

A total of 97 transvaginal scans were performed from 4 to 12 weeks gestation in normal and accurately dated gestations. The sequential appearance of six structures were examined: (1) the gestational sac only was present during week 4; (2) the yolk sac appeared in week 5; (3) the fetal pole with detectable heart motion was first seen in week 6; (4) the single unpartitioned ventricle in the brain marked week 7; (5) the falx cerebri appeared during week 9; and (6) the appearance and the disappearance of the physiologic midgut herniation were seen in week 8 and week 11, respectively. Inasmuch as the time in gestation at which these structures appear characterizes the gestational age more than any measurement at this age, we propose a practical method to determine the correct gestational age in early first-trimester pregnancy.

Fetal breathing—related nasal fluid flow velocity in uncomplicated pregnancies

OBJECTIVEnOur purpose was to determine the Doppler ultrasonographic characteristics of fetal breathing-related nasal fluid flow velocity in uncomplicated pregnancies.nnnSTUDY DESIGNnFetal nasal flow velocity was studied in 52 uncomplicated pregnancies at gestational ages ranging from 22 to 41 weeks. The evaluation of fetal breathing-related nasal fluid flow velocity was performed with ultrasonography combined with color flow and spectral Doppler analysis.nnnRESULTSnThe study revealed that the breath-to-breath interval and duration of the inspiratory phase of the fetal breathing-related nasal flow increased from 22 to 35 weeks and decreased thereafter. The breath-to-breath interval (milliseconds) at 33 to 35 weeks (1203.9 +/- 295.7 SD) was approximately twice what it was in the earliest age group (22 to 25 weeks); subsequently it decreased by approximately 25% in the term group (38 to 41 weeks). A positive correlation existed between the mean breathing-related nasal peak inspiratory flow velocity and advancing gestational age (r = 0.56, p = 0.0008), and between the inspiratory flow velocity acceleration and advancing gestational age (r = 0.53, p = 0.0076).nnnCONCLUSIONnChanges in fetal breathing activity during uncomplicated pregnancies can be determined by measurement of fetal breathing-related nasal fluid flow velocity. Our observations in uncomplicated pregnancies may be useful in future studies of these parameters in complicated pregnancies such as those at risk for pulmonary hypoplasia.

First-trimester midgut herniation: a high-frequency transvaginal sonographic study

The application of high-frequency transvaginal sonography offers new opportunities in scanning for malformations during the first trimester of pregnancy. Scanning of the anterior abdominal wall and the umbilical cord insertion at this gestational age is feasible. A cross-sectional study of 61 embryos-fetuses from 7 to 12 weeks of gestation was performed to observe the physiologic midgut hernia. This herniation was detected in 64% of the cases at 8 weeks, in 100% during weeks 9 and 10, and in 25% at 11 weeks gestation. None of the fetuses studied at 12 weeks had a midgut herniation. Vaginal sonography of the well-dated fetus at 12 weeks can confirm the final development of the anterior abdominal wall.

Fetal breathing characteristics and postnatal outcome in cases of congenital diaphragmatic hernia

OBJECTIVEnOur purpose was to determine characteristics of fetal breathing activity by recording fetal nasal fluid flow velocity in cases of congenital diaphragmatic hernia.nnnSTUDY DESIGNnFetal breathing-related nasal fluid flow was studied in 47 patients at 34 to 41 weeks of gestation, 16 cases of antenatally diagnosed congenital diaphragmatic hernia and 31 cases of uncomplicated pregnancy. The examination was performed by ultrasonography combined with color-flow and spectral Doppler analysis. An average of 25 breath cycles from each case was determined for each of the following timing parameters: breath-to-breath interval, time of inspiration, time of expiration, and ratio of time of inspiration and time of expiration.nnnRESULTSnIn all cases with uncomplicated pregnancy fetal breathing-related nasal fluid flow was seen at the level of the nose, and the timing components of this flow were determined as control values. In two cases with diaphragmatic hernia no perinasal flow was demonstrated, although fetal breathing movements observed as chest wall movements were present. The other 14 cases with congenital diaphragmatic hernia who demonstrated perinasal flow had the following postnatal outcome: one stillbirth, five neonatal deaths (group I), and eight survived and were discharged (group II). The study revealed that the time of expiration (in milliseconds) in group II (493.2 +/- 34.3 SEM) was significantly (p = 0.0030) shorter than in group I (653.4 +/- 38.4) and in cases of uncomplicated pregnancy (633.6 +/- 18.5). The value of the time of inspiration/time of expiration ratio in group II was approximately 15% higher than in group I and approximately 30% higher than in cases of uncomplicated pregnancies.nnnCONCLUSIONSnObservation of fetal breathing-related nasal fluid flow velocity in cases of antenatally diagnosed congenital diaphragmatic hernia provides a rationale for the hypothesis that time of expiration and the time of inspiration/time of expiration ratio may be useful in the prediction of postnatal outcome. We speculate that the changes in the group of survivors may represent a compensatory phenomenon by causing intermittent changes in the volume of fluid within the lungs.

An unusual case of rebound ovulation during conservative management of an ectopic pregnancy following ovum donation

SummaryConservative medical management of ectopic gestations may be difficult in patients with elevated levels of β-hCG and cardiac activity. This case highlights the difficulty of managing such patients. Doppler flow studies and serum P, if available, should be used and can help determine those patients requiring repeated dosing of methotrexate. Patients using donor gametes and hormonal supplementation who subsequently develop an ectopic gestation may experience “re-bound” ovulation, which further clouds the clinical picture. Careful follow-up using serial blood testing and ultrasound study is essential in the correct interpretation of a potentially confusing clinical picture.