Biomedical subjects

S C Mitra

Publications and source records attributed to S C Mitra.

At least 19 recordsLinked to original sources

PubMed1997

Morphometric study of the placental vessels and its correlation with umbilical artery Doppler flow.

OBJECTIVE: To determine the changes in the vessel-wall thickness and the radius of the lumen in tertiary-stem villi of the placenta with advancing gestational duration and their relationship to umbilical artery Doppler flow studies. METHODS: Placentas from 63 miscarriages and preterm and term deliveries (between 19 and 40 weeks) were used for morphometric study of the tertiary-stem villi vessels. Each woman had undergone Doppler flow study of the umbilical artery. The resistance index (RI) was determined from the Doppler flow velocity waveform. Placental paraffin sections of 4-micron thickness were stained with hematoxylin and eosin and with periodic acid-Schiff reagents. The tertiary-stem villi and their vessels were examined microscopically and assessed morphometrically using a personal computer with math co-processor and a touch-sensitive screen overlying a video monitor. The monitor received microscopic images from a video camera that was mounted on a microscope. We determined vessel-wall thickness by tracing the outer and inner circumferences of digitized vessel-wall images. RESULTS: Wall thickness, but not lumen size, of the tertiary-stem villi vessels decreased significantly overall at a rate of 0.63micron/week (P < .001). The rate of decrease was 0.64micron/week (P < .001) during the second trimester and 0.50micron/week (P < .001) during the third trimester. There was a significant correlation between the decrease in thickness and in RI (r = 0.83 [P < .001], r = 0.78 [P < .001] in the second and third trimesters, respectively). Resistance indices were all within normal limits. CONCLUSIONS: Placental tertiary-stem villi vessel-wall thickness decreases with advancing gestational age. There is a correlation between the changes in RI of the umbilical artery Doppler flow and the changes in mean wall thickness of the placental vessels.

Female↗

PubMed1995

Fetal renal artery and umbilical artery Doppler flow and fetal urine output.

The object of this study was to determine if a correlation exists between the resistance index (RI) of the umbilical artery, the RI of the fetal renal artery, and hourly urine output by fetuses of normal pregnancies. Doppler flow study of the fetal renal artery and the umbilical artery was performed in 110 fetuses between 19 and 40 weeks' gestation. Color and pulse wave Doppler was used to obtain the flow velocity waveforms. The RI of the flow velocity waveforms was calculated. Fetal bladder volume was calculated by transverse, anteroposterior, and longitudinal diameters obtained from coronal and transverse sonographic images of the fetal urinary bladder. The difference in bladder volume at 30-minute intervals was used to determine hourly urine output. Gestational age has a positive linear association with fetal urine output (P < 0.01). The RI of the fetal renal artery has a negative linear association with gestational age (P < 0.05). The RI of the umbilical artery decreased with an increase in gestation age (P < 0.01). There was a significant correlation between the RI of the umbilical artery (P < 0.01) and the fetal renal artery (P < 0.05) and hourly urine output by the fetus. The RI of the fetal renal artery decreased with gestational age. Hourly urine output of the fetus increased with gestational age. The RI of the umbilical artery and the fetal renal artery had a significant correlation with fetal urine output.

Blood Flow Velocity↗

PubMed1995

Umbilical venous Doppler waveform without fetal breathing: its significance.

Umbilical venous waveforms by Doppler ultrasound are seen normally during fetal breathing movements. Each waveform extends two to four fetal cardiac cycles. During Doppler study of gross intrauterine growth retardation (IUGR) and twin to twin transfusion cases, single or double peaked umbilical venous waveforms were detected with each fetal cardiac cycle. Umbilical arterial Doppler study detected minimal, absent, or reverse diastolic flow. In these fetuses, the ratio of right and left ventricular diameters at the atrioventricular valve level was increased, and pulse-wave and color Doppler study showed tricuspid regurgitation. This tricuspid regurgitation caused reverse flow in the umbilical vein from the right atrium and inferior vena cava and produced characteristic venous waveforms. These umbilical waveforms were associated with gross IUGR or cardiac failure of the fetuses with perinatal morbidity and mortality.

Female↗

PubMed1994

Effect of maternal cocaine abuse on renal arterial flow and urine output of the fetus.

OBJECTIVE: Our purpose was to study the short-term effect of maternal cocaine abuse on blood flow of the fetal kidney and the fetal hourly urine output. STUDY DESIGN: Thirty-three pregnant patients of various gestational ages with a history of cocaine abuse were studied. Patients were included if the urine specimen was positive for cocaine on the day of study. Patients were excluded if the urine specimen was positive for any other vasoactive substances or medications. Color and pulsed wave Doppler studies were used to obtain the flow velocity waveform of the fetal renal artery. The resistance index was calculated from systolic and diastolic values of flow velocity waveforms, Longitudinal, transverse, and anteroposterior diameters of the fetal urinary bladder were measured from transverse and coronal images at their maximum diameters, and the bladder volume was calculated. The hourly urine output of the fetus was measured from the difference in the bladder volume at half-hour intervals. As controls, 110 normal pregnancies between 19 and 40 weeks were similarly studied for normal values. The resistance index of the fetal renal artery and the hourly fetal urine output of the two groups were compared. RESULTS: The resistance index of the fetal renal artery of normal pregnancies had a negative association with gestational age (p < 0.05). Cocaine-exposed fetuses had a significantly higher resistance index of the renal artery (p < 0.01) than did normal fetuses of corresponding gestational ages. A decrease in the hourly urine output of cocaine-exposed fetuses was observed, compared with normal controls of corresponding gestational ages (p < 0.001). CONCLUSION: The resistance index values of fetal renal artery and fetal urine output were affected by maternal cocaine abuse.

Cesarean Section↗

PubMed1988