Intra-amniotic pressures following vaginal gemeprost prior to first and second trimester termination of pregnancy

Intra-amniotic pressures were measured following 1 mg gemeprost for cervical preparation before first trimester vacuum aspiration (n = 10) and following 2 mg gemeprost before second trimester dilatation and evacuation (n = 15). Twenty-five women, matched for gestational age and parity, who did not receive gemeprost served as controls. Compared to control values (2-8 mmHg), basal intra-amniotic pressure (IAP) was significantly increased after 1 mg and 2 mg of gemeprost (median 20.0, range 4-45 mmHg, median 20.0, range 8-60 mmHg, respectively). Uterine contractions were recorded in 8 of 10 subjects after 1 mg (median delta IAP 28.0, 95% CI 10.0-42.6 mmHg) and 14 of 15 subjects after 2 mg (median delta IAP 52.5, 95% CI 26.7-60.3 mmHg). Gemeprost produces an increase in uterine contractility which may be additional to cervical softening properties and which may be responsible for the adverse effects of pain and bleeding experienced by some women prior to termination.

Fetal breathing movements in oligohydramnios are not increased by aminoinfusion

OBJECTIVE

To determine whether fetal breathing movements (FBM) in pregnancies with oligohydramnios change with restoration of amniotic fluid volume.

DESIGN

A prospective experimental study.

SETTING

Fetal Medicine Unit, tertiary referral hospital.

SUBJECTS

16 women with singleton pregnancies complicated by severe oligohydramnios.

INTERVENTIONS

Restoration of amniotic fluid volume by transabdominal amnioinfusion. Controls comprised pregnancies in which infused fluid leaked vaginally, so that oligohydramnios was not corrected.

MAIN OUTCOME MEASURES

Change in total breathing movements, change in FBM incidence derived from 40 min recordings immediately before and after amnioinfusion.

RESULTS

There was no significant difference in the change in total breathing movements or in the change in incidence of FBM between the 10 pregnancies in which amniotic fluid volume was restored, and the other six in which fluid leaked after infusion and volume was not restored. In both groups, there was no significant change with infusion in number of FBM (mean change -72, 95% CI -218 to +74 in the fluid-retained group and -64, 95% CI -273 to +145 in the fluid-leaked group) and incidence of FBM (median change -2.5%, range -27 to +10 in the fluid retained group and -4.5%, range -34 to +15 in the fluid-leaked group).

CONCLUSIONS

This study suggests that restitution of amniotic fluid volume in human pregnancies complicated by severe oligohydramnios does not acutely alter the incidence of FBM. These data support an increasing literature suggesting that impairment of fetal breathing is not the mechanism for oligohydramnios-related pulmonary hypoplasia.

Mimicking low amniotic pressure by chronic pharyngeal drainage does not impair lung development in fetal sheep

OBJECTIVE

The etiology of oligohydramnios-related pulmonary hypoplasia is not understood but is known to involve chronic lung liquid loss. We tested the hypothesis that low amniotic pressure in oligohydramnios disturbs the normal tracheal-amniotic pressure gradient to increase lung liquid loss and impair lung development.

STUDY DESIGN

Chronic pharyngeal catheterization with drainage to the exterior was used in 15 fetal sheep to mimic reduced amniotic pressure at the upper airway in the presence of normal amniotic fluid volume.

RESULTS

Pharyngeal pressures relative to amniotic pressures were negative in all drained fetuses (mean +/- SE -3.0 +/- 0.6 mm Hg), in contrast to positive pressures in controls (0.7 +/- 0.1 mm Hg). There was no significant difference in lung weight or deoxyribonucleic acid relative to body weight, or in lung morphometry, between 10 fetuses drained for 10 to 21 days and their control cotwins.

CONCLUSION

Mimicking low amniotic pressure in the upper airway by chronic fetal pharyngeal drainage does not impair lung development in fetal sheep.

Relief of presumed compression in oligohydramnios: amnioinfusion does not affect umbilical artery Doppler waveforms

The suggestion that amnioinfusion improves umbilical artery Doppler indices of downstream resistance in oligohydramnios by relieving cord compression was investigated by obtaining waveforms before and immediately after amnioinfusion in 16 pregnancies with severe oligohydramnios. There was no significant difference in the change in umbilical artery pulsatility index (PI) between 11 pregnancies in which amniotic fluid volume was restored (mean delta PI = -0.07, 95% confidence interval -0.17 to +0.07), and 5 pregnancies in which immediate vaginal leakage of infused fluid prevented restitution of amniotic fluid volume. Fetal heart rate did not change significantly in either group. End-diastolic frequencies did not return with restitution of amniotic fluid volume in the 2 pregnancies in which they were absent before infusion (absent in 1, reverse in 1). This study suggests that restitution of amniotic fluid volume in human pregnancies complicated by severe oligohydramnios does not acutely alter the umbilical artery PI.

Normal amniotic pressure throughout gestation

OBJECTIVE

To characterize amniotic pressure (AP) in pregnancies with normal amniotic fluid volume.

DESIGN

Observational study, mainly cross-sectional.

SETTING

Fetal medicine unit within a tertiary referral hospital.

SUBJECTS

Patients undergoing transamniotic invasive procedures in whom amniotic fluid volume was subjectively assessed as normal on ultrasound. Those beyond 16 weeks with a deepest vertical pool on ultrasound less than 3.0 or greater than 8.0 cm were excluded. Overall 194 pregnancies were studied on 232 occasions between 7 and 38 weeks gestation.

INTERVENTIONS

Manometry readings referenced to the top of the maternal abdomen were obtained via a fluid-filled line from the needle hub and either connected to a pressure transducer (n = 190) or held vertically against a ruler (n = 42).

MAIN OUTCOME MEASURES

AP in mm Hg, AP corrected for gestational age (z scores), semi-quantitative ultrasonic indices of amniotic fluid volume, clinical variables.

RESULTS

AP in singleton pregnancies increased with advancing gestation (P less than 0.001), and the sigmoid-shaped regression curve plateaued in the mid-trimester. AP z scores were not influenced by volume-related phenomena such as twin gestation, the deepest vertical pool, or amniotic fluid index, nor by maternal age, parity, gravidity, fetal sex, or subsequent spontaneous preterm delivery.

CONCLUSIONS

These findings suggest that AP is not principally determined by intrauterine volume. We speculate that AP, which reflects change in uterine tension as a function of radius, may instead be determined by gestation-specific anatomical and hormonal influences on gravid uterine musculature. A reference range for AP has been constructed for use in amnioinfusion and amnioreduction procedures.

Fetal urine biochemistry: an index of renal maturation and dysfunction

OBJECTIVE

To construct a reference range for fetal urinary sodium, potassium, urea, creatinine, calcium and phosphate with gestation and to assess to what extent these biochemical indices are modified in fetuses with lower urinary tract obstruction.

DESIGN

Prospective descriptive study.

SETTING

Royal Postgraduate Medical School London.

SUBJECTS

24 women between 17 and 35 weeks gestation with an ultrasound diagnosis of fetal lower urinary tract obstruction, with or without renal dysplasia and a control group of 26 women between 16 and 33 weeks gestation with normal amniotic fluid volume and fetal anatomy.

INTERVENTIONS

Fetal urine samples (1-100 ml) were aspirated from the control fetuses either before termination of pregnancy (n = 9) or at the time of intrauterine transfusion for Rh alloimmunization (n = 17). The fetuses with obstructive uropathy had urine samples aspirated on one occasion (n = 14) or serially (n = 10).

MAIN OUTCOME MEASURES

Relation between urine biochemistry and renal damage ascertained clinically or at postmortem.

RESULTS

In the control group, urinary sodium and phosphate decreased and creatinine increased significantly with gestational age, consistent with increasing fetal glomerular filtration rate and progressive maturation of tubular function. Urinary sodium and calcium were significantly higher in fetuses with renal dysplasia compared with those with lower urinary tract obstruction but normal renal histology or normal clinical outcome. Serial urinary samples from fetuses with obstructive uropathy showed more pronounced deviation from the normal with increasing gestation in all fetuses with renal dysplasia. The highest sensitivity in the detection of renal dysplasia was shown by urinary calcium (100%) whereas urinary sodium showed the best specificity (80%).

CONCLUSION

Renal damage is the direct effect of urinary obstruction, rather than an association so that treatment should start as soon as possible. Urinary biochemistry may be helpful in the management of these patients.

Uterine-peritoneal amniotic fluid leakage: an unusual complication of intrauterine shunting

Bilateral pleuroamniotic shunting was performed at 33 weeks' gestation in a fetus with bilateral hydrothorax, hydrops, and gross polyhydramnios. The procedure was successful, but acute amniotic fluid leakage into the maternal peritoneal cavity occurred soon after. This produced marked maternal discomfort and transient oligohydramnios, with consequent fetal distress. Expectant management was adopted in view of fetal lung immaturity. Resolution of maternal ascites occurred within 24 hours and the fetal heart rate normalized as amniotic fluid reaccumulated. The pregnancy progressed uneventfully thereafter.

Amnioinfusion increases amniotic pressure in pregnant sheep but does not alter fetal acid-base status

To investigate the recent suggestion that fetal hypoxemia and acidemia in polyhydramnios are secondary to raised amniotic pressure, 5 to 15 L of normal saline solution was infused intraamniotically at 100 ml/min in seven ewes. Amniotic pressure increased linearly by 1.0 +/- 0.013 (mean +/- SEM) mm Hg per liter infused. Infusion of 15 L produced a mean rise in amniotic pressure of 15.2 +/- 1.2 mm Hg (p less than 0.001) but no significant change in fetal pH, PCO2, PO2, fetal heart rate, or mean arterial pressure. A similar rise in amniotic pressure and lack of change in blood gas values occurred in two control ewes infused intraperitoneally. Rupture of the membranes occurred in two of three amnioinfusions of 15 L. We conclude that acute amnioinfusion raises amniotic pressure in sheep but does not alter fetal blood gas status.

Fetal breathing during chronic lung liquid loss leading to pulmonary hypoplasia

The mechanism of oligohydramnios-related pulmonary hypoplasia (PH) is not understood, but is known to involve chronic loss of lung liquid. In order to investigate the recent suggestion that fetal breathing movements are absent or diminished in oligohydramnios-related PH, we made continuous recordings of fetal breathing movements (FBM) during chronic lung drainage in tracheostomized fetal sheep. FBM remained present throughout the drainage period. There was no significant difference in the number or duration of FBM epochs in tracheostomized fetuses compared to controls, although there was a slight reduction in incidence between 126 and 133 days (P = 0.02). PH in the fetuses undergoing chronic lung liquid drainage was confirmed by significant reductions in lung weight, volume, DNA, and total airspace, and in altered maturation. This study is consistent with other data suggesting that inhibition of FBM is not the primary mechanism of oligohydramnios-related pulmonary hypoplasia.

Direct antenatal fetal electrocardiographic waveform analysis

OBJECTIVE

To establish a technique for continuous recording of fetal electrocardiograms (ECG) for waveform analysis in the antenatal period.

DESIGN

Prospective descriptive study.

SETTING

Fetal Medicine Unit, Queen Charlotte's and Chelsea Hospital, London, UK.

SUBJECTS

35 women undergoing antenatal fetal blood sampling.

INTERVENTIONS

One end of an insulated Cooner wire was attached to the sampling needle and the other to an automatic ECG-ST waveform analyser.

MAIN OUTCOME MEASURES

ECG signals were obtained with the needle in the fetal abdomen during intrahepatic umbilical vein sampling or aspiration of fetal urine but not when it was in the placental cord insertion.

RESULTS

Continuous recording of the T/QRS ratio was obtained for a total of 166 min (mean 8 min per fetus) from 20 fetuses (16-38 weeks). The T/QRS ratio had no correlation with gestational age and fetal heart rate and was similar to values described in term fetuses in labour.

CONCLUSIONS

The technique described can identify ST waveform changes and may be useful in the investigation of fetal cardiac arrhythmias, intrauterine growth retardation and in monitoring fetal transfusions.

Diagnostic and therapeutic transabdominal amnioinfusion in oligohydramnios

We report our experience with 92 antenatal amnioinfusion procedures. In order to facilitate ultrasound visualization, a diagnostic infusion was attempted at a median of 22 weeks (range 16-36) in 61 pregnancies with oligohydramnios in the absence of ruptured membranes on clinical examination. The procedure was successful in 58 (95%). Infusion (mean volume 181 mL, range 40-64) significantly increased (P less than .001) the deepest pool of amniotic fluid to a mean of 3.2 cm. Suspected fetal anomalies were then confirmed in 27 of 30 cases, whereas kidneys were clearly demonstrated in three fetuses suspected of renal agenesis. In addition, previously unsuspected anomalies were identified in five. Vaginal leakage indicating ruptured membranes occurred in 16 women. Leakage occurred in zero of 24 patients with, compared to 16 of 35 without, fetal urinary disorders (chi 2 = 15.1, P less than .001), which does not support the recent suggestion that amnioinfusion causes rather than unmasks rupture of the membranes. Membranous detachment was observed by ultrasound in 13 patients, 11 of whom leaked vaginally. Information obtained at amnioinfusion led to a change of etiologic diagnosis in eight (13% of subjects). Forty serial infusions were performed in nine women as a pilot study to prevent oligohydramnios sequelae. There were no skeletal deformities; three neonates survived, and five of the six perinatal deaths had normal lung-body weight ratios. Overall, only two of 89 infusions (2.2%) were complicated by clinical amnionitis. Our findings support a role for amnioinfusion in oligohydramnios.

Preinduction cervical assessment by Bishop's score and transvaginal ultrasound

In this pilot study, 50 patients underwent preinduction cervical assessment by digital Bishop Score (BS) and transvaginal ultrasonography. The BS was lower in 7 patients requiring caesarean section than in 43 delivered vaginally (P = 0.017). Of seven ultrasound parameters examined, six (cervical length, width, dilatation, application and position and lower segment thickness) were similar in both groups. Cervical angle, however, was more acute in those delivered abdominally than vaginally (median = 60 degrees and 90 degrees, respectively, P = 0.002). Posterior cervical angle was more accurate than BS in predicting vaginal delivery (Kappa = 0.48 versus 0.21). Patient discomfort was significantly less with transvaginal ultrasound than digital examination. Combining posterior cervical angle greater than 70 degrees and BS greater than 5 yielded the best accuracy in predicting successful induction of labour (sensitivity = 88%, specificity = 100%, Kappa = 0.68).

Fetal blood sampling from the intrahepatic vein for rapid karyotyping in the second and third trimesters

One hundred and twelve fetuses with structural anomalies (n = 84), intrauterine growth retardation (n = 21) or amniotic fluid volume disorders (n = 7) detected by ultrasound underwent blood sampling from the intrahepatic vein for rapid karyotyping. The procedure was successful in 95.5%. 12.5% of the fetuses had an abnormal karyotype. Fetal bradycardia was observed in two fetuses (1.8%) and intraperitoneal bleeding in three (2.7%). There were three procedure-related losses but these were not due to the intrahepatic vein sampling itself. Fetal blood sampling is the method of choice for rapid karyotyping in the second and third trimesters, and the intrahepatic vein is an alternate site when access is difficult or failure to sample occurs at the placental cord insertion. Additional advantages of fetal blood sampling at the intrahepatic vein include absence of cord complications, reduced risk of fetal blood loss and fetomaternal haemorrhage, and the lack of need to confirm the fetal origin of the sample.

Behavioral changes in fetal sheep caused by vibroacoustic stimulation: the effects of cochlear ablation

We measured the effects of 2 minutes of vibroacoustic stimulation on the activity of unanesthetized fetal sheep in utero. We were unable to detect any changes in activity after stimulation with a model 5C electrolarynx. With more powerful stimulation using a mechanical oscillator, fetal electrocortical activity desynchronized. Fetal breathing and eye movements changed with electrocortical activity and there was an increase in nuchal muscle activity. Stimulation caused a small decrease in fetal heart rate. Responses to stimulation were not seen in four of the five fetuses with bilateral cochlear ablation. These results indicate that in fetal sheep the auditory apparatus is necessary for the detection of vibroacoustic stimuli. The difference in responsiveness of the sheep and human fetus appears to be because of a difference in central processing after detection of the stimulus.

Endocrine pancreatic function in growth-retarded fetuses

Maternal-fetal glucose gradient and fetal plasma glucose, insulin, and glucagon were measured in 63 fetuses: 34 controls and 29 with growth retardation (nine with and 20 without end-diastolic frequencies in the umbilical artery). Maternal-fetal glucose gradient and fetal glucagon levels were higher in the growth-retarded group than in controls (P less than .001), whereas fetal insulin and glucose concentrations were lower (P less than .001). Although maternal-fetal glucose gradient, fetal glucose, and insulin concentrations were similar among the growth-retarded fetuses, fetuses without end-diastolic frequencies in the umbilical artery had higher fetal glucagon levels (P = .01) than those with end-diastolic frequencies. In growth-retarded fetuses, the increase in fetal glucagon might reflect a compensatory response to hypoglycemia and appears to be a better index of fetal compromise than is glucose or insulin.

Fetal liver dysfunction in Rh alloimmunization

The liver enzymes, aspartate transaminase (AST), alanine transaminase (ALT), gamma glutamyl transpeptidase (GGT) and alkaline phosphatase (ALP), were measured in the blood of 25 fetuses with severe Rh alloimmunization at the time of their first, second and third intravascular transfusions and in 17 comparison fetuses. In the comparison group, GGT increased with advancing gestation (r = 0.7; P = 0.002), whereas ALP, AST and ALT did not correlate with gestational age. Rh hydropic fetuses (n = 8) had higher blood ALT levels than the comparison fetuses (P = 0.008) had significantly increased transaminases when compared with non hydropic fetuses (n = 17). In hydropic fetuses, AST correlated with the nucleated red cell count before transfusion (r = 0.94; P = less than 0.0001). Fetal transaminases were no longer increased in hydropic fetuses by the second (AST) or third (ALT) transfusion. In both hydropic and non hydropic fetuses, GGT increased by the second transfusion (median percentage change +85%, range -83% to +596%; P = 0.003). The rise in fetal GGT was transitory and correlated with the increase in fetal haematocrit at the first transfusion (r = 0.58; P = 0.006). This study reports liver dysfunction secondary to extramedullary erythropoiesis in Rh alloimmunization and implicates portal hypertension for the rise in fetal GGT with transfusion.

Further predictors of renal dysplasia in fetal obstructive uropathy: bladder pressure and biochemistry of 'fresh' urine

Urine was aspirated on two consecutive days from the dilated bladder of nine fetuses with lower urinary tract obstruction. Gestational age ranged from 17 to 35 weeks. Renal dysplasia was diagnosed histologically in four fetuses, whereas the other five had normal renal histology or only partial dysplasia. Urinary sodium (Na+) and osmolality (Osm) decreased significantly in the second urine sample 1 day after bladder emptying (median decrease: Na+ = -11.3 per cent; Osm = -13.3 per cent). Although there were no significant differences between fetuses with or without renal dysplasia, normalization of an initially raised urine Na+ concentration occurred at the second sample in a fetus with partially normal renal histology, thus correcting a false-positive diagnosis of dysplasia. Bladder pressure was measured at the time of the first urine sampling in seven fetuses and in a further eight with bladder outlet obstruction undergoing a single urine aspiration at 18-28 weeks. Bladder pressure was increased above the reference range in 8 of 15 fetuses with urinary obstruction, but there was no correlation between pressure and the degree of impairment of renal function. Although no conclusive clinical guidelines can be drawn from this study for the evaluation of fetal renal function, these findings suggest that, in lower urinary tract obstruction, tubular reabsorption is impeded by the standing pressure in the urinary tract and that improvement of renal function may occur following relief of obstruction.

Vibroacoustic stimulation is not associated with sudden fetal catecholamine release

The safety of vibroacoustic stimulation (VAS), which produces marked changes in fetal heart rate, movements and behavioural state, remains unclear. In order to determine whether VAS is associated with catecholamine release, we measured plasma noradrenaline and adrenaline in 13 appropriately grown normoxaemic fetuses between 28 and 40 weeks gestation immediately before and 60 and 75 s after VAS. Over this time interval, VAS is known to increase fetal heart rate. There was no significant change in either noradrenaline (median change = +0.06 ng/ml, P = 0.26) or adrenaline levels (median change = +0.03 ng/ml, P = 0.4). This study suggests that sympathoadrenal activation is not part of the fetal response to VAS. These findings do not support the recent suggestion that VAS may be deleterious to the fetus by provoking sudden release of catecholamines.

Continuing controversy in alloimmune thrombocytopenia: fetal hyperimmunoglobulinemia fails to prevent thrombocytopenia

Two patients with severe alloimmune thrombocytopenia were managed by weekly intrauterine platelet transfusions at 25 to 36 weeks. In one patient high-dose immunoglobulin was also administered weekly to the mother, and high maternal and fetal immunoglobulin levels were achieved. Fetal platelet counts were similar in both patients. The only variable that affected fetal platelet concentration was the posttransfusion platelet count from the previous transfusion.

Limited role of fetal blood sampling in prediction of outcome in intrauterine growth retardation

Fetal acid-base status was evaluated on 66 blood samples taken for rapid karyotyping from 58 growth-retarded fetuses. Before blood sampling, doppler blood flow studies of the umbilical artery showed end-diastolic frequencies to be absent in 32 fetuses (group 1) and present in 26 (group 2). Fetuses with chromosomal (n = 4) or structural (n = 8) abnormalities were excluded from subsequent analysis. Gestational age at blood sampling (27.8 [95% CI 26.5-29.1] vs 32.2 [30.4-34.1] weeks) and time from sampling to delivery (median 2 (range 0-35] vs 14 [0-77] days) were significantly lower in group 1 than group 2. There were no perinatal deaths in group 2 whereas mortality in group 1 was 65.4%. There were significant differences between the groups at blood sampling in pH, pO2, pCO2, base equivalents, and nucleated-red-cell count, but within group 1 these measurements were similar in surviving fetuses and those who died perinatally. Since acid-base determination does not predict perinatal outcome in growth-retarded fetuses, fetal blood sampling has a limited role in monitoring fetal wellbeing.

Amniotic pressure in disorders of amniotic fluid volume

Amniotic pressure was measured in 49 pregnancies with abnormal quantities of amniotic fluid. Among 17 with polyhydramnios, the pressure was always above the normal mean for gestation and exceeded the upper limit of normal in nine. In polyhydramnios, amniotic pressure correlated positively with the depth of the deepest pool (r = 0.65, P = .04) and negatively with fetal PO2 (r = -0.57, P = .03) and pH (r = -0.56, P = .04). Amniotic pressure was raised in all those with a deepest pool of greater than 15 cm, and was normal in all with a deepest pool less than 15 cm. Amniotic pressure fell significantly with drainage of amniotic fluid in those with raised pressure (mean 12.7 mmHg, 95% confidence interval 7.0-18.3; P = .002) but not in those with normal pressure (mean 0.3, 95% confidence interval -3.2 to +3.9; P = .82). Restoration of normal amniotic pressure in one pregnancy was accompanied by marked improvement in fetal acid-base status. Among 24 pregnancies with severe oligohydramnios, amniotic pressure was always below the normal mean, falling below the lower limit of normal in eight; whereas in another eight pregnancies with mild/moderate oligohydramnios, amniotic pressure was scattered evenly within the normal range. Amnioinfusion of 55-500 mL of normal saline in cases of severe oligohydramnios led to a significant rise in pressure (4.7 mmHg, 95% confidence interval 3.5-5.9; P less than .0001). We conclude that amniotic pressure is high in polyhydramnios and low in oligohydramnios. Pressure monitoring may be beneficial during amnioinfusion and therapeutic amniocentesis.

Effects of fetal intravenous glucose challenge in normal and growth retarded fetuses

Fetal intravenous glucose challenge test (0.75 g/kg of estimated fetal weight) was performed at 26-33 weeks gestation in 9 patients undergoing fetal blood sampling (FBS) by ultrasound guided needling from the umbilical vein. The indication for FBS was rapid karyotyping for fetal malformations in 5 (control group) and severe intrauterine growth retardation in the remaining 4 (IUGR group). Fetal blood samples were taken before the glucose infusion and after 1, 3, 5, 10 and 15 min; glucose and insulin were assayed on each occasion and acid-base balance at 0 and 5 min. Basal fetal pO2, pH, glucose and insulin were lower in the IUGR group than in controls. Following the glucose challenge, fetal glucose levels were similar in the two groups, but in the IUGR group the latter part of the glucose curve was characterized by a slower and delayed return to basal levels. In control fetuses the insulin response following the glucose challenge peaked at 3 min while in IUGR no change in insulin concentration was detected. Fetal pO2 did not change in either group; the median change in fetal pH was significantly different between the two groups (controls: +0.01; IUGR: -0.04; P less than 0.05) and there was a significant correlation between basal pO2 and the change in fetal pH (r = 0.79) (P less than 0.02). These results support the concept of a low energy state in IUGR. Fetal glucose supplementation in IUGR is unlikely to be of benefit and may even exacerbate underlying acidosis.

Fetofetal transfusion syndrome: do the neonatal criteria apply in utero?

Thirteen fetuses (five twin, one triplet) were compromised by fetofetal transfusion syndrome in six pregnancies, five in the mid trimester, and one in the third trimester. This diagnosis, which was suspected because of ultrasound findings of discordant growth, discordant amniotic fluid volumes, concordant external genitalia, and monochorial placentation, was confirmed postnatally in each. Nine fetuses underwent blood sampling to aid diagnosis and assessment of fetal wellbeing. In contrast to fetofetal transfusion syndrome investigated postnatally, a difference in haemoglobin concentration of 50 g/l or more in utero was found in only one pregnancy, which was near term, although all had fetal erythroblastaemia and a difference in weight of 20% or more. In vivo confirmation of shared circulation was achieved in two pregnancies by transfusing adult Rh negative red cells into the smaller fetus and then detecting them by Kleihauer testing in blood aspirated from the larger. Invasive procedures also yielded information on fetal blood gas measurements (acidaemia in four and hypoxaemia in six) and amniotic pressure (raised in two). We suggest that comparison of haemoglobin concentrations is inaccurate in fetofetal transfusion syndrome in utero, the diagnosis of which may necessitate detection of a shared circulation using a marker such as adult red cells.

Fetal blood sampling from the intrahepatic vein: analysis of safety and clinical experience with 214 procedures

Transabdominal fetal blood sampling under ultrasonic guidance was performed at the intrahepatic vein on 214 occasions in 177 fetuses. In 72 cases, an intravascular transfusion was also attempted at the same site. In 91.1% of the samplings, more than 1 mL of pure fetal blood was obtained, and in 89.9% of transfusions, fetal hematocrit or platelet concentration was raised to a satisfactory level. Fetal bradycardia and intraperitoneal bleeding occurred in 2.3% of the cases. Among fetuses at low risk, there was only one intrauterine death, which occurred 3 weeks after the procedure, and one spontaneous abortion in a patient with twin pregnancy. In fetuses with Rh/Kell alloimmunization or perinatal alloimmune thrombocytopenia, the survival rate was 86%. Four liver enzymes were assayed in the blood of 13 fetuses that underwent transfusions at the intrahepatic vein and 13 controls in whom the site of sampling was the umbilical vein at the placental cord insertion. No differences were found between the groups at the subsequent transfusion 2-5 weeks later. The intrahepatic vein is an alternate site of sampling/transfusion when access is difficult or failure occurs at the placental cord insertion. This approach minimizes the risks of fetal blood loss, fetomaternal hemorrhage, arterial vasospasm, and cord tamponade.

Fetal cystic hygromata: insights gained from fetal blood sampling

Twelve second-trimester fetuses with cystic hygroma underwent fetal blood sampling for rapid karyotyping, haematologic evaluation, and blood gas analysis. An abnormal karyotype was found in seven cases: monosomy X in five, trisomy 21 in one, and trisomy 13 in the other. Eight of ten fetuses undergoing blood gas analysis showed hypoxaemia, five of which were growth-retarded. Nine pregnancies were terminated. Of the remaining three, only one fetus survived the perinatal period.

Plasma renin activity in fetal disease

Fetal plasma renin activity (PRA) was measured in 42 pregnancies. Compared to control fetuses, PRA was elevated in three of four hypoxemic fetuses, in two of five with hydrops and in two of five with uropathies. PRA did not change with transfusion in seven alloimmunized fetuses. This study demonstrates PRA in human fetuses and suggests that the renin-angiotensin system can respond to stimuli in fetal life.

Low amniotic pressure in oligohydramnios--is this the cause of pulmonary hypoplasia?

The mechanism by which oligohydramnios produces lung hypoplasia is not understood. The current theory that extrinsic compression of the fetal thorax causes hypoplasia, either by inhibiting breathing movements or by squeezing out lung liquid, is not supported by observational or experimental data, or by our finding of decreased amniotic pressure around the fetus in oligohydramnios. We hypothesize that lung hypoplasia results from excess loss of lung liquid because of a reduction in amniotic pressure, and hence an increase in the alveolar-amniotic pressure gradient. The magnitude of this increased pressure gradient is calculated to exceed the small standing tracheal pressure; thus low amniotic pressure overcomes the normal laryngeal retentive mechanisms and allows a larger quantity of lung liquid to escape. In the prevention of pulmonary hypoplasia, a role is suggested for the instillation of artificial amniotic fluid to restore normal amniotic pressure.

Fetal macrocytosis in association with chromosomal abnormalities

Mean red cell volume (MCV) was determined in 264 fetuses between 15-41 weeks. After exclusion of anemic, hypoxic, and chromosomally abnormal fetuses, the MCV in 208 umbilical venous samples was shown to decrease with gestation (r = 0.64; P less than .001), and a normal range was constructed by linear regression analysis. An elevated MCV was found in both fetuses with triploidy, in four of five with monosomy X, and in four of ten with trisomies 18 or 21. The MCV was similarly raised in four of five fetuses with gross anomalies in whom cytogenetic cultures had failed. Significant correlations were found in chromosomally abnormal fetuses between the elevation in MCV and both the nucleated red cell (r = 0.69; P less than .01) and reticulocyte counts (r = 0.57; P less than .05). There was a similar correlation with nucleated red cells in 16 severely anemic fetuses with Rh disease, 12 of whom had a raised MCV. Elevation in MCV was unrelated to hypoxia. Macrocytosis had a sensitivity of 71% and a specificity of 95% in the second trimester for predicting an abnormal karyotype in nonanemic fetuses (kappa index 0.60). Fetal MCV may provide clinically useful information while one awaits culture results. We suggest that karyotyping be considered in fetuses undergoing blood sampling for other indications in whom the MCV is raised.

Maternal-fetal glucose gradient in normal pregnancies and in pregnancies complicated by alloimmunization and fetal growth retardation

Maternal and fetal glucose concentrations were measured simultaneously in 54 pregnancies in which fetal blood sampling was conducted between 18 and 34 weeks gestation. Twenty-five pregnancies were normal (group 1), 13 were complicated by fetomaternal alloimmunization (group 2), and 16 by intrauterine growth retardation (group 3). The maternal glucose concentration was similar in the three groups. The fetal glucose level was significantly lower in growth-retarded (mean = 2.7 mmol/L) than in normal pregnancies (mean = 3.5 mmol/L). There was a statistically significant gradient between maternal and fetal glucose concentrations in groups 1 and 3, but no gradient was found in group 2. Maternal and fetal glucose concentrations were significantly correlated in all groups, but the correlations were distinct. For a given maternal glucose concentration, fetal glucose was higher in patients with alloimmunization and lower in patients with intrauterine growth retardation than in normal pregnancies. In patients with intrauterine growth retardation, fetal PO2 correlated positively with fetal glucose and inversely with maternal fetal glucose gradient.

Transvaginal ultrasonic assessment of endometrial growth in spontaneous and hyperstimulated menstrual cycles

Endometrial thickness and reflectivity were assessed by transvaginal ultrasound in both spontaneous and hyperstimulated menstrual cycles. Two groups of women with ovulatory cycles were examined; women in group 1 had unexplained infertility and women in group 2 were having artificial insemination by donor because of reduced spermatogenesis; a third group (group 3) comprised women with tubal infertility undergoing hyperstimulation for in-vitro fertilization. There was no difference in endometrial thickness or reflectivity between the three groups. A basic pattern of endometrial appearance common to all cycles was found, consisting of hypoechoic, isoechoic and hyperechoic images, occurring in the early follicular, late follicular and luteal phases, respectively. In all three groups a positive correlation was found between proliferative phase plasma oestradiol concentration and endometrial thickness. Group 1 r = 0.403, P less than 0.01; group 2 r = 0.439, P less than 0.01; and group 3 r = 0.617, P less than 0.01. There was a progressive increase in endometrial growth throughout the normal cycle until a plateau was reached 5 days after the LH surge. This pattern was also seen without acceleration of the process in hyperstimulated cycles, despite supranormal levels of oestrogen. Assessment of endometrial thickness is not a useful variable in monitoring hyperstimulated cycles. No aberrations of endometrial growth or pattern were observed in the women with unexplained infertility.

Fetal hyperinsulinism in anencephaly

Insulin was measured in the blood collected in utero from three midtrimester anencephalic fetuses. The hyperinsulinism found could be due to an underutilization of glucose in the absence of most of the brain and could be responsible for the relatively normal growth in anencephaly despite the absence of the hypothalamohypophysial axis.

Lack of effect of high-dose antioestrogen on the maturation and in-vitro fertilization of human oocytes

Thirty-four women requesting laparoscopic sterilization underwent a fixed schedule regimen for multiple follicular development which included norethisterone and clomiphene citrate. Follicle aspiration for oocyte recovery was attempted laparoscopically 34 h after administration of 5000 IU human chorionic gonadotrophin (HCG). Nineteen women were given 80 mg tamoxifen orally 4 h prior to HCG injection, while 15 acted as controls. There was no statistical difference in fertilization rates in vitro between tamoxifen-treated patients and controls (80 and 68% respectively). In addition, the morphological characteristics of the oocytes, the rates of cleavage, and the concentrations of oestradiol, progesterone and androstenedione in follicular fluid were similar in the two groups. Tamoxifen was detected in substantial amounts in follicular fluids of patients given tamoxifen. These results suggest that high-dose tamoxifen, in clinically used doses, does not adversely affect the final stages of maturation or the fertilization and early cleavage of human oocytes.

Pathophysiology of pressure changes during intrauterine transfusion

Intraperitoneal and umbilical vein pressure readings were obtained during intrauterine transfusion in patients with Rh alloimmunization. In 15 nonacidotic fetuses, mean umbilical vein pressure before transfusion (4.5 mm Hg, SD = 2.3) increased by 4.6 mm Hg (delta umbilical vein pressure confidence intervals +2.8 to +6.4; p less than 0.0001) with transfusion. delta Umbilical vein pressure correlated positively with the increase in hematocrit level (r = 0.55; p less than 0.05) and negatively with gestational age (r = -0.58; p less than 0.05). Basal umbilical vein pressure was raised in the only acidotic fetus, whereas delta umbilical vein pressure was 0. Intraperitoneal pressure was recorded in 11 fetuses before and after transfusion, five of which were associated with fetal heart rate changes or preexisting ascites. Basal intraperitoneal pressure (2.5 mm Hg, confidence intervals 1.4 to 3.6) was significantly lower than basal umbilical vein pressure (confidence intervals, 3.2 to 5.8; p less than 0.02). In uncomplicated intraperitoneal transfusions, intraperitoneal pressure rose significantly (delta intraperitoneal pressure = +5.8; confidence intervals 2.9 to 8.8; p less than 0.005). In four transfusions associated with fetal bradycardia or tachycardia, delta intraperitoneal pressure (range, 16 to 26) was greater than in uncomplicated transfusions (range, 1 to 9). delta Intraperitoneal pressure was 0 in the fetus with ascites. These results implicate increases in umbilical vein pressure and intraperitoneal pressure in immediate complications of intrauterine transfusion, and support a role for intraperitoneal pressure monitoring during intraperitoneal transfusion.

Intrauterine manometry: technique and application to fetal pathology

A technique is described for measuring pressure within the amniotic cavity and within fetal vessels and/or body compartments. Two saline-filled catheters were connected at one end to needles inserted during indicated invasive procedures and at the other to silicon strain gauge transducers. In 36 pregnancies with normal liquor volume, stable intra-amniotic pressure (IAP, range 1-14 mmHg) increased with gestation (r = 0.48, p less than 0.01). In pregnancies complicated by severe oligohydramnios, IAP was less than or equal to 1 mm Hg and rose to normal levels with saline amnioinfusion. Raised IAP (range 17-26 mm Hg), found in pregnancies with gross polyhydramnios, fell with drainage of amniotic fluid. Subtraction manometry was used to determine supra-amniotic pressure within the intervillus space, umbilical vein, umbilical artery, abdominal and thoracic cavities, and the urinary tract in normal and/or pathological fetuses. Low intravesical and intrapelvicalyceal pressures (median 6.5, range 2-10 mm Hg) were noted in fetuses with obstructive uropathies. Intrauterine subtraction manometry appears to be a useful tool in the understanding of fetal pathophysiology and may be of clinical benefit in the therapeutic drainage and infusion of amniotic fluid and in the assessment of certain fetal disease states.

Labor outcome of juvenile primiparae in a population with a high incidence of contracted pelvis

Labor outcome of primiparae less than 17 years was compared with non-juvenile primiparae in a population with a high incidence of contracted pelvis. Juvenile primiparae were referred to hospital on the basis of age, whereas non-juveniles were referred for an obstetric complication. There was no statistical difference in rates of cesarean section, Ventouse, operative delivery, low birth weight, or perinatal mortality between 538 juveniles and 5294 older "high risk" mothers. Symphysiotomy rates were actually higher in the juveniles (12.6% vs. 9.7%, P less than 0.05). These data support the practice of hospital referral for juvenile African women in labor.

Fetal outcome in obstetric cholestasis

Obstetric cholestasis has been associated with a high incidence of stillbirth and perinatal complications. Between 1975 and 1984, 83 pregnancies were complicated by cholestasis. Meconium staining occurred in 45%, spontaneous preterm labour in 44%, and intrapartum fetal distress in 22%. Of 86 infants two were stillborn and one died soon after birth. Perinatal mortality fell from 107 in a previous series from this hospital (1965-1974) to 35/1000 in this series. Cardiotocography, estimations of oestriol, liver function tests and ultrasonic assessment of amniotic fluid volume failed to predict fetal compromise, whereas amniocentesis revealed meconium in 8 of 26 pregnancies. Early intervention was indicated in 49 pregnancies, 12 because of fetal compromise. This study suggests that intensive fetal surveillance, including amniocentesis for meconium, and induction of labour at term or with a mature lecithin/sphyngomyelin ratio, may reduce the stillbirth rate in this 'high-risk' condition.

The fetal intrahepatic umbilical vein as an alternative to cord needling for prenatal diagnosis and therapy

Seventy-one fetal blood samplings (FBS) were attempted from the intrahepatic portion of the umbilical vein (IHV) at 18-34 weeks; 54 were attempted primarily and 17 secondarily after a failed attempt at the placental cord insertion. Fetal blood was obtained in 89 per cent of the cases. Intravascular transfusion (IVT) was attempted on 31 occasions and successful in 24 (77 per cent). In all cases of failed sampling or transfusion via the IHV, prenatal diagnosis and/or therapy was accomplished using alternative procedures. On only one occasion was the procedure postponed. There were no losses or neonatal morbidity attributable to the procedure. FBS from the IHV may be considered as an alternative approach to sampling the placental cord insertion. It is recommended in cases where the approach to the placental cord insertion is difficult or hazardous.

Maternal features of obstetric cholestasis: 20 years experience at King George V Hospital

Between 1965 and 1984, 139 pregnancies in 125 women were complicated by obstetric cholestasis (OC). Prevalence increased from 0.1% in the first 10-year period to 0.2% in the second (p less than 0.001), following recognition of the adverse fetal risks of this condition. Perinatal data from both series, 1965-1974 and 1975-1984 have previously been published. Mothers in the latter series were more likely to be of Anglosaxon than Mediterranean origin (p less than 0.001) and did not have underlying haemolytic conditions. Diagnostic criteria changed considerably over the 20 years, such that liver biopsy was no longer needed, gastroenterological consultation was sought less frequently (p less than 0.001) and newer diagnostic criteria of increased bile acids with negative hepatitis serology were increasingly employed. Biochemical data were broadly similar in the 2 groups. An understanding of the clinical and laboratory features of this disease facilitates early diagnosis, which is imperative if intensive fetal surveillance is to reduce the high stillbirth rate in OC.

Changes in fetal acid base status during intravascular transfusion

Umbilical venous pH, PCO2, PO2, and base excess was measured immediately before and after 72 intravascular transfusions in 34 fetuses with erythroblastosis fetalis. In 67 uncomplicated transfusions, infused adult blood led to a mean (95% confidence intervals) fall in pH (0.037, CI 0.029 to 0.044) and base excess (2.03, CI 1.61 to 2.45) and a mean rise in PCO2 (0.24 kPa, CI 0.13 to 0.35). These changes correlated significantly with the increase in fetal haemoglobin and packed cell volume. Five transfusions were associated with complications within six hours: intrauterine death in two, fetal-distress necessitating delivery in two, and preterm labour in one. Two had pre-existing acidosis, whereas two of the three with normal blood gas and acid base measurements before transfusion had acute changes that were outside the normal ranges that had been established in uncomplicated transfusions.

Hysterosalpingographic diagnosis of a single cervical ectopic ureter

Single ectopic ureters terminating in the female genital tract are rare congenital anomalies caused by an abnormally lateral origin of the ureteric bud from the mesonephric duct in the three- to four-week embryo. The ureter remains intimately involved with mesonephric duct remnants, which acquire a communication with müllerian structures. Hysterosalpingography in a continent infertile patient outlined a single cervical ureter from a hypoplastic kidney draining into Gartner's duct remnants. No previous case of single cervical ectopic ureter has been reported without a müllerian anomaly, nor has a single cervical ureter been demonstrated on hysterosalpingography.