Adrenal changes in chorioamnionitis

Adrenal volumes in fetuses delivering prior to 32 weeks' gestation: An MRI pilot study

INTRODUCTION

Spontaneous preterm birth prior to 32 weeks' gestation accounts for 1% of all deliveries and is associated with high rates of morbidity and mortality. A total of 70% are associated with chorioamnionitis which increases the incidence of morbidity, but for which there is no noninvasive antenatal test. Fetal adrenal glands produce cortisol and dehydroepiandosterone-sulphate which upregulate prior to spontaneous preterm birth. Ultrasound suggests that adrenal volumes may increase prior to preterm birth, but studies are limited. This study aimed to: (i) demonstrate reproducibility of magnetic resonance imaging (MRI) derived adrenal volumetry; (ii) derive normal ranges of total adrenal volumes, and adrenal: body volume for normal; (iii) compare with those who have spontaneous very preterm birth; and (iv) correlate with histopathological chorioamnionitis.

MATERIAL AND METHODS

Patients at high risk of preterm birth prior to 32 weeks were prospectively recruited, and included if they did deliver prior to 32 weeks; a control group who delivered an uncomplicated pregnancy at term was also recruited. T2 weighted images of the entire uterus were obtained, and a deformable slice-to-volume method was used to reconstruct the fetal abdomen. Adrenal and body volumes were obtained via manual segmentation, and adrenal: body volume ratios generated. Normal ranges were created using control data. Differences between groups were investigated accounting for the effect of gestation by use of regression analysis. Placental histopathology was reviewed for pregnancies delivering preterm.

RESULTS

A total of 56 controls and 26 cases were included in the analysis. Volumetry was consistent between observers. Adrenal volumes were not higher in the case group (p = 0.2); adrenal: body volume ratios were higher (p = 0.011), persisting in the presence of chorioamnionitis (p = 0.017). A cluster of three pairs of adrenal glands below the fifth centile were noted among the cases all of whom had a protracted period at risk of preterm birth prior to MRI.

CONCLUSIONS

Adrenal: body volume ratios are significantly larger in fetuses who go on to deliver preterm than those delivering at term. Adrenal volumes were not significantly larger, we hypothesize that this could be due to an adrenal atrophy in fetuses with fulminating chorioamnionitis. A straightforward relationship of adrenal size being increased prior to preterm birth should not be assumed.

Antenatal diagnosis of chorioamnionitis: A review of the potential role of fetal and placental imaging

Chorioamnionitis is present in up to 70% of spontaneous preterm births. It is defined as an acute inflammation of the chorion, with or without involvement of the amnion, and is evidence of a maternal immunological response to infection. A fetal inflammatory response can coexist and is diagnosed on placental histopathology postnatally. Fetal inflammatory response syndrome (FIRS) is associated with poorer fetal and neonatal outcomes. The only antenatal diagnostic test is amniocentesis which carries risks of miscarriage or preterm birth. Imaging of the fetal immune system, in particular the thymus and the spleen, and the placenta may give valuable information antenatally regarding the diagnosis of fetal inflammatory response. While ultrasound is largely limited to structural information, MRI can complement this with functional information that may provide insight into the metabolic activities of the fetal immune system and placenta. This review discusses fetal and placental imaging in pregnancies complicated by chorioamnionitis and their potential future use in achieving non-invasive antenatal diagnosis. This article is protected by copyright. All rights reserved.

Six year follow up of infants with bacteriuria on screening

OBJECTIVE

To determine the value of screening for bacteriuria in infants with special emphasis on the natural course of untreated asymptomatic bacteriuria, renal growth, and renal damage.

DESIGN

Prospective six year follow up of infants with bacteriuria on screening in an unselected infant population.

SETTING

Paediatric outpatient clinic.

PATIENTS

50 Infants (14 girls, 36 boys) with bacteriuria on screening verified by suprapubic aspiration from an unselected population of 3581 infants in a defined area of Gothenburg.

INTERVENTIONS

Children with asymptomatic bacteriuria and normal findings on initial urography were untreated, although other infections were treated.

MAIN OUTCOME MEASURES

Culture of urine and determination of C reactive protein concentration every six weeks for the first six months after diagnosis, every three months from six months to two years, and every six months between two and three years; thereafter yearly urine culture. Evaluation of renal concentrating capacity with a desmopressin test; radiological examination, including first and follow up urography and micturition cystourethrography without antibiotic cover; and measurement of renal parenchymal thickness and renal surface area.

RESULTS

Of the original 50 infants, 37 (12 girls, 25 boys) were followed up for at least six years. Two infants developed pyelonephritis within two weeks after bacteriuria was diagnosed; the others remained free of symptoms. 45 Infants were untreated; the bacteriuria cleared spontaneously in 36 and in response to antibiotics given for infections in the respiratory tract in eight. Recurrences of bacteriuria were observed in 10 of the 50 children, of whom one had pyelonephritis. No child had more than one recurrence. At follow up urography in 36 of the 50 children (9 girls, 27 boys) after a median of 32 months no child had developed renal damage. First samples tested for renal concentrating capacity showed significantly higher values than those from a reference population (mean SD score 0.50, 95% confidence interval 0.21 to 0.79; p less than 0.001), but the last samples showed no significant difference (mean SD score 0.08, -0.24 to 0.40; p greater than 0.05).

CONCLUSIONS

Mass screening for bacteriuria in infancy results primarily in detection of innocent bacteriuric episodes and is not recommended.

Fetal adrenal development during the second trimester of gestation

Four hundred and fifty pairs of adrenals were studied from human fetuses ranging in age from 15 to 27 weeks of gestation (menstrual age). They were collected from spontaneous and medical abortions. The adrenal weight increased from 0.2 to 1.5 g during the second trimester. The left adrenal was significantly heavier than the right for the same gestational age. The length (L1), the height (L2) and the thickness (L3) of the adrenals were measured. The index of length (L1 x L2 x L3) correlated well with the fetal age, except for the Potter Syndrome in which it was decreased. This index could be a useful indicator for ultrasonographic and pathologic studies of the fetal adrenal gland. The cells of the fetal cortex contained lipid droplets during the first weeks of the mid-trimester, and this storage progressively decreased after 20-21 weeks. The fatty transformation that is used as an indicator of the mode of death of stillborn infants cannot be applied to abortions during the second trimester. In a few instances, hypoxia was associated with adrenal hypertrophy.

Mucosal metaplasia and chronic inflammation in the middle ear of infants receiving intensive care in the neonatal period

The histological findings in the middle ear cavity of 72 infants of varying gestations, birthweights, and ages are presented. All infants died after receiving ventilatory support and oxygen for longer than 14 days. In 5 infants there was no detectable histological abnormality. In the remainder, a wide range of lesions was seen including glandular metaplasia, retained squamous debris, squamous polyps, otitis media, and destruction of ossicles. None of the cases of otitis media was diagnosed before necropsy; all were associated with pneumonia. No single specific infectious agent predominated. Several factors could contribute to the spectrum of lesions, and these include persistent amniotic squamous debris, infection, and the effects of oxygen and a nasal airway. The possible implications of these findings are discussed, and it is argued that similar changes of lesser severity could be present in survivors in whom otitis media and conduction hearing defects could be expected.

Stress response and its relationship to cystic (pseudofollicular) change in the definitive cortex of the adrenal gland in stillborn infants

The adrenal glands of 41 fresh stillbirths were studied and a 'stress response' pattern could be seen in 28. In these glands the stress response was characterised by compact cell change, lipid depletion, excess pyroninophilia, and dilatation of the very prominent granular endoplasmic reticulum. Scattered areas of cytolysis of cells, especially of the definitive cortex, gave rise to the commonly seen cystic (pseudofollicular) change and it was obvious that cells undergoing lysis were severely 'stressed'. In 2 infants there was a 'clear cell reversal' pattern. Histological and ultrastructural changes of the stress response were not identified in 11. Infants of low birthweight score were somewhat more commonly represented in the group that did not show a stress response. Cytolytic changes accompanying a stress response were commoner in immature infants. It is argued that cystic (pseudofollicular) change in the adrenal cortex of the newborn signifies a previous stress reaction.

Prolonged rupture of membranes, pre-eclamptic toxaemia, and respiratory distress syndrome

A retrospective analysis was made of the incidence and severity of the idiopathic respiratory distress syndrome (RDS) in babies of less than 35 weeks' gestation born at this hospital from January 1967-December 1974. There was a lower incidence of RDS in babies born after pregnancies complicated only by prolonged rupture of membranes (PRM) (19%) and in babies born vaginally after pregnancies complicated only by pre-eclamptic toxaemia (PET) (18%) compared with the incidence of RDS after uncomplicated pregnancies (35%). Babies born vaginally who developed RDS after pregnancies complicated by PRM or PET had less severe disease compared with those who developed RDS after uncomplicated pregnancies. Mortality in babies who developed severe RDS was not influenced by the occurrence of PRM or PET. The biological implication of the study is that certain complications of pregnancy may accelerate pulmonary surfactant production in preterm babies.

Amniotic fluid cortisol after premature rupture of membranes

Total amniotic fluid cortisol concentration was studied in 12 patients at 24 to 34 weeks of gestation after premature rupture of membranes of one to eight days duration. Rupture of the membranes of less than 24 hours duration was associated with normal amniotic fluid cortisol concentrations. Rupture of membranes for more than 24 hours was associated in 10 of 12 patients with higher than normal amniotic fluid cortisol levels. The rise in amniotic fluid cortisol concentrations following premature rupture of the membranes may reflect increased fetal or maternal cortisol production or both, and could explain enhanced lung maturation in such infants.