No abstract

Ultrasonographic (US) findings were correlated with clinical outcome in seven cases of meconium peritonitis detected with prenatal US during a 2-year period. Nineteen previously reported cases were also reviewed. US findings included intraabdominal calcifications (n = six cases), fetal ascites (n = 3), echogenic ascites without calcifications (n = 1), bowel dilatation (n = 2), and polyhydramnios (n = 5). Following delivery, six infants were still alive after a mean follow-up of 13 months (range, 6-26 months); the seventh died of hydrocephalus. Of the six, four required surgical correction of a small-bowel perforation and two did not. All six are thriving, and none has yet been found to have cystic fibrosis. In the 19 previously reported cases, there were only two cases of cystic fibrosis, neither with intraabdominal calcifications. The presence of calcifications was significantly associated with causes other than cystic fibrosis. Prenatally diagnosed cases of meconium peritonitis are associated with cystic fibrosis less frequently than previous studies suggest.

To further elucidate antenatal sonographic features of fetal urethral obstruction and attempt to determine which features might predict subsequent outcome, 40 in utero cases were reviewed. All fetuses had dilated urinary bladders and/or thickened bladder walls; in 47.5% of fetuses a dilated posterior urethra was seen. Only 15 fetuses (37.5%) survived the neonatal period. Survivors tended to present later in gestation than nonsurvivors. Poor prognostic indicators included oligohydramnios (20 of 21 subsequently died), absence of caliectasis (20 of 24 died), a large amount of urine ascites (five of six died), and dystrophic bladder wall or peritoneal calcification (five of five subsequently died). Conversely, 14 of 19 (74%) fetuses without definite oligohydramnios survived the neonatal period.

Previous reports have shown that visualization of the "lemon" sign on fetal cranial sonograms may indicate the presence of spina bifida before 24 weeks. To further characterize this sign and determine whether other factors might be associated with it, the authors retrospectively (n = 31) and prospectively (n = 19) evaluated 50 fetuses with spina bifida. The lemon sign was noted in 32 (64%), including 24 of 27 (89%) fetuses evaluated before 24 weeks. The presence of both ventricular dilatation, found in 41 (82%) of the fetuses, and a lemon sign correctly predicted spina bifida in all but one case. The location of the spinal defect and other anomalies were not associated with the lemon sign. The lemon sign is an important indicator of spina bifida, particularly in high-risk pregnancies, and should improve sonographic detection of spina bifida before 24 weeks.

To assess the possible relationship between the degree of maternal hydration and the sonographic identification of minimal fetal renal pyelectasis, a prospective study was performed in which fetuses demonstrating mild dilation of the renal pelvis (maximum diameter ranging from 3 to 11 mm) were reexamined after the mothers refrained from oral intake for 12 hours. Complete or almost complete resolution of the pyelectasis occurred in only four of 17 kidneys (23.5 per cent) while the remaining fetal kidneys demonstrated little or no change in the degree of pyelectasis following maternal dehydration. This observation, as well as previous experimental research , suggests that the state of maternal oral hydration is not a major cause of minimal fetal pyelectasis. Additionally, the observation of fetal pyelectasis measuring at least 3 mm in greatest dimension is common, occurring in approximately 18 per cent of fetuses older than 24 menstrual weeks. (Key words: fetal renal pyelectasis, minimal; maternal dehydration) Hydronephrosis may be secondary to a spectrum of etiologies. Although many cases of hydronephrosis are related to obstructive uropathy, wellestablished nonobstructive etiologies are known. 1 • 2 Excessive fluid intake (over hydration) is a well· recognized factor leading to minimal dilatation of the renal collecting system in adults. High-volume drip infusion urography can also lead to temporary minimal dilatation of calyces, renal pelves. and ureters secondary to the combination of intravenous volume load and the diuretic effect of urographic contrast agents. Patients afflicted with diabetes insipidus typically show some prominence of the urinary tract collecting structures due to the high volume of hyptonic urine conveyed by this system.A distended maternal urinary bladder provides an important acoustic window in obstetrical ultrasound. To distend the maternal urinary bladder, sonographers frequently ask gravid women to drink as much as 1500 ml of fluid over a period as short as one hour. Such aggressive oral hydration in a nonpregnant young healthy patient obviously leads to an element of intravascular volume expansion, elevated renal plasma flow, and subsequently increased glomerular filtration and urine excretion.