Infant Sleep Hazards and the Risk of Sudden Unexpected Death in Infancy

OBJECTIVE

To examine the effects of infant sofa-sleeping, recent use by caregivers of alcohol, cannabis, and/or other drugs, and bed type and pillows, on the risk of sudden unexpected death in infancy (SUDI) in New Zealand.

STUDY DESIGN

A nationwide prospective case-control study was implemented between March 2012 and February 2015. Data were collected during interviews with parents/caregivers. "Hazards" were defined as infant exposure to 1 or more of sofa-sleeping and recent use by caregivers of alcohol, cannabis, and other drugs. The interaction of hazards with tobacco smoking in pregnancy and bed sharing, including for very young infants, and the difference in risk for Māori and non-Māori infants, also were assessed.

RESULTS

The study enrolled 132 cases and 258 controls. SUDI risk increased with infant sofa-sleeping (imputed aOR [IaOR] 24.22, 95% CI 1.65-356.40) and with hazards (IaOR 3.35, 95% CI 1.40-8.01). The SUDI risk from the combination of tobacco smoking in pregnancy and bed sharing (IaOR 29.0, 95% CI 10.10-83.33) increased with the addition of 1 or more hazards (IaOR 148.24, 95% CI 15.72-1398), and infants younger than 3 months appeared to be at greater risk (IaOR 450.61, 95% CI 26.84-7593.14).

CONCLUSIONS

Tobacco smoking in pregnancy and bed sharing remain the greatest SUDI risks for infants and risk increases further in the presence of sofa-sleeping or recent caregiver use of alcohol and/or cannabis and other drugs. Continued implementation of effective, appropriate programs for smoking cessation, safe sleep, and supplying safe sleep beds is required to reduce New Zealand SUDI rates and SUDI disparity among Māori.

Smoking in pregnancy is a key factor for sudden infant death among Māori

AIM

To examine the sudden unexpected death in infancy (SUDI) disparity between Māori and non-Māori in New Zealand.

METHODS

A nationwide prospective case-control study ran from March 2012 to February 2015. Exposure to established SUDI risk factors was analysed to investigate the disparity experienced by Māori. Infant ethnicity was based on mother's ethnicity. Māori ethnicity was prioritised. Non-Māori includes Pacific, Asian, NZ European and Other.

RESULTS

There were 137 cases and 649 controls. The Māori SUDI rate was 1.41/1000 live births compared to 0.53/1000 for non-Māori. Parents/caregivers of 132 cases (96%) and 258 controls (40%) were interviewed. Smoking in pregnancy was associated with an equally increased SUDI risk for Māori (adjusted OR = 8.11, 95% CI = 2.64, 24.93) and non-Māori (aOR = 5.09, 95% CI = 1.79, 14.47), as was bed-sharing (aOR = 3.66, 95% CI = 1.49, 9.00 vs aOR = 11.20, 95% CI = 3.46, 36.29). Bed-sharing prevalence was similar; however, more Māori controls smoked during pregnancy (46.7%) than non-Māori (22.8%). The main contributor relating to increased SUDI risk for Māori/non-Māori infants is the combination of smoking in pregnancy and bed sharing.

CONCLUSION

The association between known SUDI risk factors, including bed sharing and/or smoking in pregnancy and SUDI risk, is the same regardless of ethnicity. Māori infants are exposed more frequently to both behaviours because of the higher Māori smoking rate.

Late stillbirth post mortem examination in New Zealand: Maternal decision-making

BACKGROUND

For parents who experience stillbirth, knowing the cause of their baby's death is important. A post mortem examination is the gold standard investigation, but little is known about what may influence parents' decisions to accept or decline.

AIM

We aimed to identify factors influencing maternal decision-making about post mortem examination after late stillbirth.

METHODS

In the New Zealand Multicentre Stillbirth Study, 169 women with singleton pregnancies, no known abnormality at recruitment, and late stillbirth (≥28weeks gestation), from seven health regions were interviewed within six weeks of birth. The purpose of this paper was to explore factors related to post mortem examination decision-making and the reasons for declining. We asked women if they would make the same decision again.

RESULTS

Maternal decision to decline a post mortem (70/169, 41.4%) was more common among women of Māori (adjusted odds ratio (aOR) 4.99 95% confidence interval (CI) 1.70-14.64) and Pacific (aOR 3.94 95% CI 1.47-10.54) ethnicity compared to European, and parity two or more (aOR 2.95 95% CI 1.14-7.62) compared to primiparous. The main reason for declining was that women 'did not want baby to be cut'. Ten percent (7/70) who declined said they would not make this decision again. No woman who consented regretted her decision.

CONCLUSION

Ethnic differences observed in women's post mortem decision-making should be further explored in future studies. Providing information of the effect of post mortem on the baby's body and the possible emotional benefits of a post mortem may assist women faced with this decision in the future.

The combination of bed sharing and maternal smoking leads to a greatly increased risk of sudden unexpected death in infancy: the New Zealand SUDI Nationwide Case Control Study

BACKGROUND

Despite a major reduction in overall infant mortality, sudden unexpected death in infancy (SUDI) continues to be of concern in New Zealand, as the rate is high by international standards, and is even higher in indigenous Māori.

AIM

To identify modifiable risk factors for SUDI.

METHODS

A three-year (1 March 2012-28 February 2015) nationwide case-control study was conducted in New Zealand.

RESULTS

There were 137 SUDI cases, giving a SUDI mortality rate of 0.76/1,000 live births. The rate for Māori was 1.41/1,000, Pacific 1.01/1,000 and non-Māori non-Pacific (predominantly European) 0.50/1,000. The parent(s) of 97% of the SUDI cases were interviewed. Six hundred and forty-nine controls were selected and 258 (40%) were interviewed. The two major risk factors for SUDI were: maternal smoking in pregnancy (adjusted OR=6.01, 95% CI=2.97, 12.15) and bed sharing (aOR=4.96, 95% CI=2.55, 9.64). There was a significant interaction (p=0.002) between bed sharing and antenatal maternal smoking. Infants exposed to both risk factors had a markedly increased risk of SUDI (aOR=32.8, 95% CI=11.2, 95.8) compared with infants not exposed to either risk factor. Infants not sharing the parental bedroom were also at increased risk of SUDI (aOR=2.77, 95% CI=1.45, 5.30). Just 21 cases over the three-year study were not exposed to smoking in pregnancy, bed sharing or front or side sleeping position.

CONCLUSIONS

This study has shown that many of the risk factors that were identified in the original New Zealand Cot Death Study (1987-1989) are still relevant today. The combination of maternal smoking in pregnancy and bed sharing is extremely hazardous for infants. Furthermore, our findings indicate that the SUDI prevention messages are still applicable today and should be reinforced. SUDI mortality could be reduced to just seven p.a. in New Zealand (approximately one in 10,000 live births).

Classification of causes and associated conditions for stillbirths and neonatal deaths

Accurate and consistent classification of causes and associated conditions for perinatal deaths is essential to inform strategies to reduce the five million which occur globally each year. With the majority of deaths occurring in low- and middle-income countries (LMICs), their needs must be prioritised. The aim of this paper is to review the classification of perinatal death, the contemporary classification systems including the World Health Organization's International Classification of Diseases - Perinatal Mortality (ICD-PM), and next steps. During the period from 2009 to 2014, a total of 81 new or modified classification systems were identified with the majority developed in high-income countries (HICs). Structure, definitions and rules and therefore data on causes vary widely and implementation is suboptimal. Whereas system testing is limited, none appears ideal. Several systems result in a high proportion of unexplained stillbirths, prompting HICs to use more detailed systems that require data unavailable in low-income countries. Some systems appear to perform well across these different settings. ICD-PM addresses some shortcomings of ICD-10 for perinatal deaths, but important limitations remain, especially for stillbirths. A global approach to classification is needed and seems feasible. The new ICD-PM system is an important step forward and improvements will be enhanced by wide-scale use and evaluation. Implementation requires national-level support and dedicated resources. Future research should focus on implementation strategies and evaluation methods, defining placental pathologies, and ways to engage parents in the process.

Does a large abdominal wall defect affect lung growth?

BACKGROUND/PURPOSE

Respiratory distress in babies with large abdominal wall defects suggests a relationship to decreased diaphragmatic movement. We evaluated pulmonary development in a fetal lamb gastroschisis model.

METHODS

We created gastroschisis in 25 fetal lambs at 60days gestation (group A). Controls were 14 nonoperated lambs. (Group B) were all delivered at term. Lung volume, histology, and type 1 (AT1)/type 2 (AT2) cell ratios (AT1 ratio) were determined. We subdivided group A, comparing lambs with a large defect and scoliosis [group A (S)] with the remainder [group A (NS)].

RESULTS

Twenty-five lambs survived (11 fetuses in group A and 14 fetuses in group B). Lung volume in group A (S) was less than in group A (NS) (p<0.05). The AT1 ratio in group A was lower than in group B (p<0.01), without any difference in radial alveolar counts (RACs) or alveolar growth, and no association between scoliosis and alveolar differentiation.

CONCLUSION

Gastroschisis in a sheep model reduces the AT1 ratio but not the RAC. Severe scoliosis affects lung volume but not the AT1 ratio, suggesting reduced diaphragmatic movement in fetuses with large abdominal defects.

Rethinking placental pathology in the PSANZ classification of unexplained stillbirth at term

BACKGROUND

Approximately 30 per cent of stillbirths are currently classified 'unexplained' using the Perinatal Society of Australia and New Zealand (PSANZ) classification system in New Zealand. This unexplained category includes deaths with placental pathology even though the importance of placental pathology and its causal relationship to stillbirth is well described.

AIMS

To determine whether unexplained stillbirths in New Zealand classified using PSANZ criteria can be more usefully classified based on placental pathology.

METHODS

Audit of the classification of cause of death among 'unexplained antepartum death' at term by perinatal pathologist review of postmortem and/or placental pathology reports using the current PSANZ Perinatal Death Classification (PDC)10 classification and a proposed 'significant placental pathology' subclassification. The main outcome measure was a change in cause of death from unexplained term stillbirth to an alternative PSANZ classification or to significant placental pathology subcategory.

RESULTS

In total, 177 unexplained stillbirths with a postmortem and/or placental pathology report in New Zealand between 2007 and 2013 inclusive were reviewed. Twenty-three cases (13%) had significant placental pathology that could have been a direct cause of the stillbirth. A further seven cases (4%) were misclassified and could be better classified within another PDC category.

CONCLUSIONS

A classification system incorporating placental pathologies which are recognised by the current literature to be causative of stillbirth would better describe stillbirths at term in New Zealand. This would benefit parental counselling and follow-up in subsequent pregnancies. A standard approach to reporting placental pathology would benefit clinicians. Education on placental pathology for clinicians working with parents experiencing stillbirth and multidisciplinary approach to classification is also recommended.

Pressure limited vesico-amniotic shunt allows normal lung growth in a fetal lamb model of obstructive uropathy

BACKGROUND

In our fetal lamb model of lower urinary tract obstruction, a pressure limited shunt preserves bladder function and renal development. This study investigates the effects on pulmonary histology.

METHODS

We created obstructive uropathy (OU) in 60-day gestation fetal lambs, ligating the urethra and urachus, and delivering them at term (130-145days). We compared pulmonary histology in 4 groups: group A, OU without shunt; group B, pressure limited shunt; group C, non-valved shunt. Shunts were inserted 3weeks post-obstruction. Group D were normal controls.

RESULTS

We compared 27 fetuses: 7 fetuses in group A, 4 fetuses in group B, 2 fetuses in group C, and 14 fetuses in group D. There was no significant difference in lung volume in any group. In group A, there were some areas of atelectasis and incomplete alveolar formation histologically. The alveoli in group A lambs lungs had a predominance of type II cells, whereas group B lambs lungs were lined by type I epithelial cells and were essentially indistinguishable from controls.

CONCLUSIONS

This study suggests that using a pressure-limited vesico-amniotic shunt in OU may preserve the renal tract and the lungs.

Can a pressure-limited V-A shunt for obstructive uropathy really protect the kidney?

BACKGROUND

In our fetal lamb model of lower urinary tract obstruction, a valved shunt preserves bladder function. This study investigates the effects on renal histology.

METHODS

We created obstructive uropathy (OU) in 60-day gestation fetal lambs, ligating the urethra and urachus, and delivering them at term (130-145days). We compared renal histology in 4 groups: group A-OU without shunt, group B-low-pressure shunt (15-54mmH2O), group C-high-pressure shunt (95-150mmH2O). Shunts were inserted 3weeks post-obstruction. Group D were normal controls.

RESULTS

We delivered 32 fetuses from 23 ewes: 13 fetuses in group A (9 survived), 6 fetuses in group B (5 survived), 7 fetuses in group C (5 survived), and 6 fetuses in group D. Histologically, we found renal tubular distention, vacuolated degeneration of tubular epithelial cells in 7 lambs, and cyst formation in 4 lambs in group A. There was renal tubular distention in two lambs, and cyst formation in one lamb in both groups B and C, with vacuolated degeneration of tubular epithelial cells observed in all but 1 lamb in each group.

CONCLUSIONS

V-A shunting prevents multicystic dysplastic kidney (MCDK). Some lambs have renal tubular distention and vacuolated degeneration of renal tubular epithelial cells.

Development of an animal model to study congenital urinary obstruction

PURPOSE

We outline the development of a reliable model of obstructive uropathy in fetal lambs highlighting our understanding of the critical time points for interventions and the variability of any such model. We identify some discoveries that may have clinical implications.

METHODS

The model requires 60-day-gestation fetal lambs. In lambs, glomerulogenesis is complete by 90 days gestation. (Term is 145 days.) The ability to develop a reliable method of creating bladder outlet obstruction in females, ligating both the urethra and urachus was critical. The lambs are bred to an accuracy of ±24 h.

RESULTS

Creating the model at 50-60 days gestation, produces different expressions of renal dysplasia in groups of lambs undergoing identical interventions at the same stage of gestation. Early complete urethral obstruction can produce the Potter phenotype. An appropriately timed vesico-amniotic shunt preserves renal development, producing a shrunken, non-compliant bladder. Shunting the normal fetal bladder at 80 days gestation produces a similar bladder. Provision of a low-pressure valve in the shunt preserves bladder development and compliance. Using a high-pressure shunt produces results similar to non-shunted lambs.

DISCUSSION

We developed a reliable animal model for obstructive uropathy. Being alert to peripheral results can lead to new findings.

Gliosis in neonatal SUDI cases

AIM

To review sudden unexpected infant deaths (SUDI) in the first 28 days of life referred to a Coronial Perinatal Forensic Pathology Service over a 10-year period from 2000 to 2009.

METHODS

Cases were collected from mortuary records, and a retrospective review of autopsy reports and other available infant records was undertaken.

RESULTS

Twenty-four neonatal SUDI were reviewed. For eight infants, a diagnosis was made at autopsy. For the remaining 16 infants, 14 (87.5%) were bedsharing at the time of death. Maori infants and those living in deprived neighbourhoods were over-represented. Only two infants were preterm, and four were growth-restricted. At post-mortem, white matter gliosis was found in 10 of the 16 (62.5%) unexplained SUDI cases.

CONCLUSION

Sudden unexpected infant deaths occur in the first month of life in association with bedsharing. Gliosis may be an important associated risk factor, and its presence indicates a previous insult of prenatal onset.

Maternal perception of fetal activity and late stillbirth risk: findings from the Auckland Stillbirth Study

BACKGROUND

  Maternal perception of decreased fetal movements has been associated with adverse pregnancy outcomes, including stillbirth. Little is known about other aspects of perceived fetal activity. The objective of this study was to explore the relationship between maternal perception of fetal activity and late stillbirth (≥28 wk gestation) risk.

METHODS

  Participants were women with a singleton, late stillbirth without congenital abnormality, born between July 2006 and June 2009 in Auckland, New Zealand. Two control women with ongoing pregnancies were randomly selected at the same gestation at which the stillbirth occurred. Detailed demographic and fetal movement data were collected by way of interview in the first few weeks after the stillbirth, or at the equivalent gestation for control women.

RESULTS

  A total of 155/215 (72%) women who experienced a stillbirth and 310/429 (72%) control group women consented to participate in the study. Maternal perception of increased strength and frequency of fetal movements, fetal hiccups, and frequent vigorous fetal activity were all associated with a reduced risk of late stillbirth. In contrast, perception of decreased strength of fetal movement was associated with a more than twofold increased risk of late stillbirth (aOR: 2.37; 95% CI: 1.29-4.35). A single episode of vigorous fetal activity was associated with an almost sevenfold increase in late stillbirth risk (aOR: 6.81; 95% CI: 3.01-15.41) compared with no unusually vigorous activity.

CONCLUSIONS

  Our study suggests that maternal perception of increasing fetal activity throughout the last 3 months of pregnancy is a sign of fetal well-being, whereas perception of reduced fetal movements is associated with increased risk of late stillbirth.

Bladder development following bladder outlet obstruction in fetal lambs: optimal timing of fetal therapy

BACKGROUND

Lower urinary tract obstruction causes both renal failure and bladder dysfunction after birth. This study examined the early bladder wall changes after creating an obstructive uropathy focusing on bladder wall thickness and muscle integrity.

METHODS

We created obstructive uropathy in fetal lambs at 60 days' gestation, ligating the urethra and urachus. The fetuses (n = 28) were delivered at 48 hours and 3, 4, 5, 7, and 14 days after obstruction and at term (145 days' gestation). Sham-operated lambs were used as controls (n = 20). Histology samples were stained using α-smooth muscle actin) immunohistochemistry and also hematoxylin-eosin, Masson trichrome, and colloidal Fe stain.

RESULTS

The bladder wall initially expanded and stretched. By day 4, the bladder wall became thicker. Histologically, the bladder in obstructed lambs demonstrated a prominent submucosal fibrotic change by 7 days. The mean bladder wall thickness at 14 days after obstruction was thicker than controls, and fibrosis was prominent.

CONCLUSION

The initial changes in the bladder wall were expansion of the muscle component followed by fibrosis. The bladder wall thickness dramatically increased 4 to 7 days after obstruction. We conclude that shunting operations to preserve bladder function may be needed earlier than expected.

Placenta accreta in the first trimester of pregnancy: sonographic findings

In a case of histologically confirmed placenta increta, decidual protrusion into the myometrium was observed sonographically at 6 weeks' gestation, corresponding to placental protrusion from a disrupted placental-uterine wall interface seen in the later part of the first and second trimester. It is hypothesized that the histologic finding of decidual scarcity in placenta accreta is not a cause but rather an end result of the recruitment of trophoblasts across the decidual-placental interface in a maternal attempt at healing and/or repair in the presence of uterine injury, disease, or malformation that accounts for the associated factors and course of the condition.

A case of amyoplasia in a monochorionic twin pregnancy: a sequela from twin-twin transfusion syndrome?

OBJECTIVE

To present and discuss the sonographic and clinical findings in one twin of a monochorionic pair affected by amyoplasia.

METHODS

On ultrasound examination at 21 weeks in a monochorionic twin pregnancy, twin I was smaller, hydropic, with multiple contractures consistent with amyoplasia and oligohydramnios. Twin II was anatomically normal with polyhydramnios.

RESULTS

The twins were delivered at 28 weeks' gestation. The clinical findings were consistent with twin-twin transfusion syndrome (TTTS).

CONCLUSION

It is postulated that TTTS may be a causative factor in the excessive incidence of amyoplasia in monozygotic twin pregnancy.

Can a pressure-limited vesico-amniotic shunt tube preserve normal bladder function?

INTRODUCTION

We have previously shown that a vesico-amniotic shunt (V-A shunt) produces fibrotic bladders with poor compliance in normal fetal lambs. We hypothesized that using a ventriculo-peritoneal shunt (V-P shunt) as a V-A shunt in normal bladders may preserve the filling/emptying cycle and normal bladder development.

MATERIALS AND METHODS

The V-A shunting in normal fetal lambs was performed at 74 days of gestation using a V-P shunt (group A) and a free-draining shunt tube (group B). Sham-operated lambs were used as controls (group C). They were all delivered at term (145 days), and the pressure-volume curve, bladder volume, and histologic features of the bladder wall were compared.

RESULT

The mean bladder volume in group B (n = 5), 5 +/- 2.4 mL, was significantly smaller (P < .01) than that in group A (n = 6), 53 +/- 14 mL, and group C (n = 10), 57.3 +/- 12 mL. The bladder wall thickness in group A was 338 + 94.2 microm; group B, 741 +/- 128 microm; and group C, 374 +/- 120 microm. Group B bladders had very poor compliance with thick bladder wall (P < .01). Histologically, group B bladders showed prominent submucosal fibrotic change, but group A bladders were similar to controls.

CONCLUSION

This study shows that a pressure-limited shunt tube for V-A shunting preserves the normal fetal bladder development.

Evaluation of sonographic diagnostic criteria for placenta accreta

PURPOSE

To compare the diagnostic value of reported sonographic criteria for placenta accreta and to develop a composite score system for antenatal evaluation.

METHOD

Sixty-six women at risk for placenta accreta were examined for 9 cases of placenta accreta that were confirmed at delivery. The performance of previously reported gray-scale and Doppler sonographic criteria for the diagnosis of placenta accreta was analyzed individually. A composite score system was developed by combining selected sensitive or specific sonographic criteria, and its performance was evaluated.

RESULTS

The criteria of obliteration of retroplacental clear space, a myometrial thickness of <1 mm, presence of vessels bridging placenta and uterine margin, disruption of the placental-uterine wall interface, and vessels crossing the sites of interface disruption showed a statistically significant association with placenta accreta. The disruption of the placental-uterine wall interface and the presence of vessels crossing these sites were the only 2 individual criteria that could distinguish placenta accreta from non-accreta, which could also be achieved by our composite score system using a cutoff value of 40, with a sensitivity of 89% and specificity of 98%.

CONCLUSION

The diagnostic performance of the sonographic diagnostic criteria used in the diagnosis of placenta accreta varies, and a composite score system improves the overall accuracy.

The maternal outcome in placenta accreta: the significance of antenatal diagnosis and non-separation of placenta at delivery

AIM

To evaluate the effects of antenatal diagnosis and subsequent placental non-separation at delivery on the maternal outcome in confirmed cases of placenta accreta.

METHOD

The perinatal database and medical records for women who delivered in the period 2000-6 in a teaching hospital in New Zealand with a diagnosis of placenta accreta or postpartum haemorrhage or hysterectomy were reviewed. In confirmed placenta accreta cases, the amount of blood loss and blood transfused at delivery and subsequent emergency hysterectomy were analysed in respect to the presence/absence of antenatal diagnosis and the management at delivery.

RESULTS

16 women had placenta accreta confirmed (15 histologically and 1 visually). Antenatal diagnosis was made in 7 women, elective Caesarean delivery planned in all, hysterectomy to follow in 5 (4 elective, 1 emergency preterm), and elective placental separation in 2 women. When an antenatal diagnosis was not made (n=9), attempted placental separation led to emergency hysterectomy for all (p=0.001). Antenatal diagnosis and placental non-separation resulted in less mean blood loss (1.4 L vs 3.6 L, p=0.003; 1.0 L vs 3.4 L, p<0.001) and mean units of blood transfused (1.2 vs 5.1, p=0.005) in the latter.

CONCLUSION

In placenta accreta, antenatal diagnosis and avoidance of placental separation may result in better maternal outcome.

Changes in cause of neonatal death over a decade

AIMS

To classify neonatal deaths at Wellington Hospital (Wellington, New Zealand) over a 10-year period and assess changes in cause of death over time.

METHODS

Retrospective audit from 1995-2004 of live-born infants > or = 20 weeks gestation dying before 28 days of age. Deaths were classified according to the PSANZ-NDC Classification guideline. The years 1995-1999 and 2000-2004 were compared to analyse for changes in cause of death.

RESULTS

There were 219 neonatal deaths: 67(31%) of these were term infants and 154 preterm; 109 infants from 1995-1999 and 110 from 2000-2004. The autopsy rate was 62% and highest in term infants (76%). Deaths due to congenital anomaly and extreme prematurity decreased over time and deaths due to infection increased.

CONCLUSIONS

Use of the PSANZ-NDC death classification system enables an accurate cause of death to be established for most neonatal deaths and allows monitoring of mortality rates over time.

Is a vesicoamniotic shunt intrinsically bad? Shunting a normal fetal bladder

INTRODUCTION

We previously demonstrated that in utero vesicoamniotic shunting of obstructive uropathy in fetal lambs produces a shrunken noncompliant bladder. We hypothesized that the normal fetal bladder filling and emptying cycle in fetal life is critical to the development of normal bladder function.

MATERIALS AND METHODS

We placed vesicoamniotic shunts in 4 normal fetal lambs at 74 days' gestation. The fetuses were delivered at term (145 days), and bladder volume and compliance were measured and compared with those measurements in 3 normal term fetuses. The lambs were then killed and the renal tracts and bladders removed submitted to histologic examination.

RESULTS

All shunted lambs survived to term. Three normal control lambs were delivered at term. The mean bladder volume in shunted lambs was 4 +/- 2.8 mL (n = 4) compared with 60 +/- 17 mL (n = 3) in control lambs (P < .05). Bladders in the shunted lambs had very poor compliance compared with normal lambs' bladders. Histologic examination of the shunted bladders showed increased fibrosis and distortion of the muscle layers compared with control bladders.

CONCLUSION

Even in the absence of obstruction, preventing normal bladder filling and emptying in fetal life produces fibrotic bladders with poor compliance.

Pressure-limited vesico-amniotic shunt tube for fetal obstructive uropathy

INTRODUCTION

In utero shunting (vesico-amniotic shunt) of obstructive uropathy in fetal lambs produces a shrunken, noncompliant bladder. We hypothesized that using a ventriculo-peritoneal shunt for the vesico-amniotic shunt may preserve the filling/emptying cycle and thus normal bladder development.

MATERIALS AND METHODS

We created obstructive uropathy in 60-day gestation fetal lambs, ligating the urethra and urachus. Vesico-amniotic shunting was performed 21 days later using the valve end of a ventriculo-peritoneal shunt (valve shunt) or silastic tubing (nonvalve shunt). They were delivered at term (145 days), and the bladder volume was measured and compared to normal term fetuses. The lambs were sacrificed, and the kidneys and bladder removed for histology.

RESULTS

Twenty-seven lambs were shunted. Of 14 valve shunts, 8 were effective. Of 13 nonvalve shunts, 11 were effective. The mean bladder volume was 57 +/- 41 mL with a valve shunt and 8.8 +/- 4.7 mL with a nonvalve shunt (P < .05) (normal term lambs, 65 +/- 18 mL, n = 5). Histology of the shunted bladders showed increased fibrosis in the submucosal and muscle layers. This was less obvious in lambs with a valve shunt.

CONCLUSION

A pressure controlled shunt for fetal obstructive uropathy improves bladder volume but does not prevent bladder wall fibrosis.

Early bladder wall changes after creation of obstructive uropathy in the fetal lamb

Vesico-amniotic shunting of obstructive uropathy in fetal lambs produced a thick-walled, poorly compliant bladder. We report the early histological changes in the obstructed bladder wall. We created an obstructive uropathy in fetal lambs at 60 days gestation by ligating the urethra and urachus. Vesicostomy or vesico-amniotic shunt tube insertion and biopsy of the bladder wall were performed 21 days later. The fetuses were delivered at term (145 days) and the kidneys and bladder sampled for histology. Colloidal iron (Col Fe), and alpha-smooth muscle actin (alpha-SMA) immunohistochemical stains were used for these samples. Seventeen fetuses were shunted with 15 biopsies taken at that time. Six (shunt failure or missed urachal ligation) were excluded. All biopsies taken at shunting had positive Col Fe and alpha-SMA. Term lambs had mild multicystic dysplastic kidney (MCDK) in five, severe MCDK in two, and hydronephrosis in four. All bladders had small volume and were severely fibrotic. Fetal shunt operations 3 weeks after the creation of obstructive uropathy provided partial preservation of renal histology but did not preserve normal bladder histology. We suggest that the high hyaluronic acid synthesis activity or hyperplasia of the myofibroblasts in the dilated fetal bladder wall at the time of shunting results in irreversible damage to the developing bladder muscle and fibrosis.

Vesicoamniotic shunt for complete urinary tract obstruction is partially effective

PURPOSE

The long-term outcome for children after antenatal intervention for obstructive uropathies is disappointing. We reported that renal dysplastic changes are well established 3 weeks after obstruction in a fetal lamb model. We used this model to explore renal development and bladder function after fetal intervention.

METHODS

We created an obstructive uropathy in fetal lambs at 60 days gestation by ligating the urethra and urachus. A vesicostomy (female) or urethrostomy (male) were performed 21 days later. The fetuses were killed at term (145 days) and bladder volume and compliance were measured. The urinary tract was processed for histologic examination.

RESULTS

Twenty two fetuses were shunted. Nine were miscarried or were still-born. Thirteen survived, and 11 had a successful shunt with a small bladder (8 +/- 5 mL) compared with controls (71 +/- 19 mL) (P < .05). Shunted bladders had poor compliance. Histologically, they had thickened submucosal connective tissue with hypertrophied muscle. Histology of the renal tissue demonstrated relatively well-preserved renal architecture with reduced nephron mass (oligonephronia) in 2 lambs and multicystic dysplastic change in 3. Six (55%) had normal nephrogenesis.

CONCLUSIONS

In our model, shunt operations after obstructive uropathy fail to preserve bladder function. Shunting ameliorated the development of cystic dysplasia, but half of the lambs had oligonephronia or multicystic dysplastic kidney. These might develop renal failure later in life.

Fetal hydrops in experimental obstructive uropathy resolves after vesicostomy formation: is this cause and effect?

The association of obstructive uropathy and hydrops is rare but often fatal. Hydrops has been observed in our fetal lamb model with obstructive uropathy. We created a vesicoamniotic shunt 21 days after creating the obstruction to explore the effect of relieving the obstruction on the hydrops. Fetal lambs underwent urethral and urachal ligation at 60 days gestation. We created a vesicostomy (female) or urethrostomy (male) in 12 lambs to release the pressure 21 days after creating the obstruction. The fetuses were delivered at term (145 days), and the urinary tract was removed for histological examination. Six fetuses had severe hydrops at the time of the vesicostomy (group A), and six had no hydrops (group B). Only two lambs from group A survived (33%), and four lambs survived from group B (66%). Three lambs miscarried, and one was stillborn from group A. Two lambs from group B miscarried. In our fetal lamb model, hydrops appears to be associated with massive urinary ascites. We hypothesize that a connection exists between urinary ascites and hydrops. Vesicostomy, by bypassing the obstruction, may allow the lambs to recover from their hydrops. However, it is possible that by 21 days after creation of the obstruction, the damage created by the hydrops is irreversible.

The early effects of urinary tract obstruction on glomerulogenesis

PURPOSE

Our obstructive uropathy model in fetal lambs showed that renal cystic changes appeared 3 weeks after obstruction. In this study, the authors investigated the changes resulting from complete urinary tract obstruction in the first 7 days after obstruction.

METHODS

An obstructive uropathy was created in fetal lambs at 60 days' gestation by ligating the urethra and urachus. They were delivered 48 hours, 3 days, 5 days, and 7 days later by cesarian section. The kidneys were removed and processed for histologic examination.

RESULTS

Eighteen fetuses were operated on and 15 (4 at 48 hours, 4 at 3 days, 2 at 5 days, and 5 at 7 days; 83%) survived. Macroscopically, bladder dilatation and slightly dilated ureters were identified from 48 hours. Microscopically, dilatation of proximal tubules started from 48 hours after obstruction and increased by 7 days. Glomerular cysts in the nephrogenic zone also were identified from 48 hours. Dysplastic changes were not found.

CONCLUSIONS

The first areas in the developing kidney that suffer damage after obstructive uropathy are the proximal tubule and the nephrogenic zone. This change started 48 hours after obstruction. Shunting procedures need to be performed considerably earlier than previously thought.

Effects of early vesicostomy in obstructive uropathy on bladder development

PURPOSE

Creation of a vesico-amniotic shunt for obstructive uropathy removes the normal fetal urination cycle. It is unclear how this affects bladder function at term. The authors measured the bladder volume and reviewed the bladder histology after fetal vesicostomy.

METHODS

The authors created an obstructive uropathy in fetal lambs at 60 days' gestation by ligating the urethra and urachus. Vesicostomy (female) or urethrostomy (male) were performed 21 days after obstruction to release the obstruction. The fetuses were killed at term (145 days).

RESULTS

Thirteen fetuses were shunted. Seven fetuses miscarried after shunting. Six survived, and 3 had a successful shunt with a very small bladder (5 to 7 mL). Two had incomplete shunts that failed some time after shunting. These both had huge bladders (399 mL). In one, the obstruction was unsuccessful. Histologic examination showed that the obstruction caused bladder muscle hypertrophy. Shunted lambs had severe fibrosis of the bladder wall and very poor bladder compliance.

CONCLUSIONS

Shunt operations after obstructive uropathy may salvage the kidney but fail to preserve bladder function. The fetus needs a normal urination cycle for normal bladder development. This requirement exists even when the obstruction is successfully bypassed.

Optimal timing of prenatal treatment of obstructive uropathy in the fetal lamb

PURPOSE

It was still unclear how urinary tract obstruction alters normal nephrogenesis and leads to renal dysplasia. The authors created an obstructive uropathy model in fetal lambs and reviewed the pathology of the obstructed kidney to determine the optimal timing for decompression of the obstruction.

METHODS

Obstructive uropathy was created in fetal lambs at 60 days' gestation by ligating the urethra and urachus. They were delivered 20 to 31 days later by cesarian section. The kidneys were processed for histologic examination.

RESULTS

Thirty-four 60-day lambs were operated on. Dysplastic changes were noted in 25 fetuses, and 24 fetuses had cysts in the nephrogenic zone. The cystic components in multicystic dysplastic kidneys (MCDK) are mainly in the proximal tubules.

CONCLUSIONS

In utero urinary tract obstruction causes reduction of numbers of functioning nephrons and produces cysts in the nephrogenic zone and in the deeper cortex. These cysts and dilated proximal tubules suppress new nephron formation. Twenty days after obstruction, there were early features of dysplasia, but the nephrogenic zones still were present. Early shunting may salvage renal function.

Renal dysplasia produced by obstructive uropathy in the fetal lamb

AIM

This study was undertaken to investigate the renal changes associated with obstruction of the urinary tract in the fetal lamb early in gestation (50 days). It was also undertaken to determine if urinary tract obstruction proximal or distal to the urinary bladder would result in varying renal morphology.

METHODS

Timed-gestation ewes at 50-days gestation were anaesthetised, and the lambs exposed. Males had their urethra and urachus ligated with a fine silastic tubing. Females had one ureter ligated with the same tubing. They were delivered at term and sacrificed. The kidneys were weighed, measured and processed for histological examination.

RESULTS

Three lambs (2 males and 1 female) survived. All 5 kidneys were small (2.2+/-0.4g, normal 17.3+/-1.3g), and had lost their normal architecture. Microscopically, these kidneys had few glomeruli, a relative abundance of stroma with apparent nodular collections of tubules surrounded in some instances by a cuff of fibrous stromal tissue.

CONCLUSION

The morphologic features produced by urinary tract obstruction at 50-days gestation in the lamb resembled those normally associated with human cystic renal dysplasia. The site of the obstruction had no effect on the development of subsequent renal pathology.

Potential confusion arising from materials presenting as possible human remains

The accurate identification of human tissues is an important part of forensic science, but may be difficult when specimens are small, fragmented, or burned. A wide variety of materials may be submitted as human, including parts of animals and nonorganic materials. Two cases involving a plastic fetal skeleton and a rubber fetus are described, which were initially considered to represent human remains, thus initiating police investigations for possible concealed stillbirth or infanticide. In one case, the remains were so deceptively real in appearance that hospital personnel initiated fibroblast cultures from an "umbilical cord". A third case of mineral concretions that resembled a human hand is also described. These cases demonstrate that protocols should be in place for the rapid assessment of all suspected human remains by pathologists, so that nonhuman material can be rapidly excluded, and police investigations terminated.

Different phenotypes of dysplastic kidney in obstructive uropathy in fetal lambs

PURPOSE

The cause of cyst production in renal dysplasia is uncertain. The authors hypothesized that different patterns of renal dysplasia result from variations in the timing and site of the urinary tract obstruction.

METHODS

The authors operated on fetal lambs at 50 and 60 days' gestation. Male lambs underwent urethral and urachal ligation and female lambs unilateral ureteric ligation. They were delivered by cesarean section at 145 days' gestation and killed.

RESULTS

Of 12 lambs operated on at 50 days' gestation, 4 survived. Of 26 lambs operated on at 60 days, 21 survived. The authors identified 3 types of dysplastic kidneys. Type A, fibrotic kidneys (2.2 g) with no cysts and interstitial fibrosis. There were reduced numbers of proximal tubules, but distal tubules and collecting ducts persisted. (50-day obstruction, n = 5 kidneys); type B, Sponge-like kidneys (37g): these had large cysts with minimal interstitial fibrosis. (87% of 60-day uretheral and urachal ligation model n = 12 kidneys); Type C, Small kidneys (4.8 g) with no large cysts (60-day Ureteric ligation model n = 7 kidneys).

CONCLUSION

The authors produced 3 different types of renal dysplasia by creating urinary tract obstruction at different sites and gestational ages.

Glomerular size in renal dysplasia secondary to obstructive uropathy: a further exploration of the fetal lamb model

BACKGROUND/PURPOSE

Creating an obstructive uropathy early in glomerulogenesis would produce multicystic dysplastic kidneys (MCDK). Measuring the mean planar area of the glomeruli (GMPA) may clarify the pathogenesis of MCDK.

METHODS

Fetal lambs at 60 days' gestation had their left ureter ligated and were delivered by cesarian section at 145 days' gestation. Kidney weight and length were recorded. GMPA in 3 zones (outer, middle, inner) of the sectioned kidney was measured using a computerized planimeter. The obstructed kidneys were compared with contralateral unobstructed kidneys. The unpaired Student's t test was used to determine significance.

RESULTS

One ewe miscarried. Four of 5 (80%) 60-day lambs survived. All had dysplastic kidneys. Mean kidney weights were 4.3 +/- 0.84 g in MCDK and 16.8 +/- 3.6 g in controls (P< .05). The GMPA of the outer, middle, and inner zones of the MCDK were 2.7 x 10(-3) mm2, 3.2 x 10(-3) mm2, and 4.0 x 10(-3) mm2, respectively. Controls were 2.8 x 10(-3) mm2, 4.4 x 10(-3) mm2, and 6.0 x 10(-3) mm2. The glomeruli of 60-day fetal kidneys were 3.0 x 10(-3) mm2, 6.1 x 10(-3) mm2, and 11.0 x 10(-3) mm2. MCDK had smaller glomeruli in the inner and middle zones than controls.

CONCLUSION

Fetal glomeruli appear to grow from the inner zone of the kidney. Early urinary tract obstruction stops this growth.

Lethal congenital dyserythropoietic anaemia type I in siblings presenting as pericardial effusions in the second trimester

Congenital dyserythropoietic anaemias (CDA) are rare inherited disorders of erythropoiesis characterised by abnormal red cell morphology and haemolysis. The diagnosis of CDA should be considered in the fetus or patient presenting with a normocytic or macrocytic anaemia especially if red cell morphology is abnormal. Three types and other possible variants have been described. There are few reports of clinical presentation of CDA in utero. We present 2 cases of lethal CDA in siblings that presented with pericardial effusions in the second trimester.

Outcome of antenatally detected cystic dysplastic kidney disease

Forty four fetuses with multicystic dysplastic kidney (MCDK) disease recognised on antenatal ultrasound were studied prospectively. In nine aborted fetuses and in five who died in the neonatal period the MCDK disease was bilateral or there were associated lethal abnormalities or syndromes. All surviving infants had unilateral disease and in six (20%) there was significant reflux into the normal contralateral kidney. Since 1988 the management of unilateral MCDK disease has been conservative with no child developing sepsis, hypertension, or malignancy. Serial ultrasound examinations suggest that MCDK lesions involute with time and conservative rather than operative management is favoured.

The outcome of fetal ventriculomegaly

Over a 5 year period 38 cases of fetal ventriculomegaly were diagnosed at Queen's Medical Centre, Nottingham. There were 12 cases of spina bifida and all patients opted for a termination of pregnancy. There were 15 cases of isolated ventriculomegaly comprising seven cases of aqueduct stenosis, four abnormalities of the corpus callosum, one cavum septum pellucidum cyst, one case of porencephaly and two cases of mild lateral ventricular dilatation. The fetuses in this group had a relatively good outcome with five babies showing normal development, three with mild development delay and one with moderate developmental delay. There was one stillbirth and five patients opted for a termination of pregnancy. Associated abnormalities were seen in seven cases and these carried a poor prognosis with one fetus stillborn, one neonatal death, and three patients opted for a termination of pregnancy. Two babies were liveborn, one has severe developmental delay and the other one is normal. The four remaining cases included two Dandy Walker syndrome, one brain tumour and one case of subdural haemorrhage. There were three terminations of pregnancy and one stillbirth in this group. The outcome of fetal ventriculomegaly depends on the presence of associated abnormalities which carry a poor prognosis. It also depends on the timing of the diagnosis as most patients will opt for a termination of pregnancy if the diagnosis is made before 24 weeks gestation. A review of the literature reveals that, excluding terminations, fetuses with isolated ventriculomegaly have an 80% chance of survival and a 50% chance of normal development.

The ultrasound markers of chromosomal disease: a retrospective study

Over a 3 year period 37 pregnancies were complicated by a chromosomal abnormality. In the two cases of trisomy 13, holoprosencephaly, facial clefting, polydactyly and growth retardation were seen. In the seven cases of trisomy 18, abnormalities of the extremities, face and heart were common. Growth retardation and diaphragmatic hernia were also demonstrated. In the 21 cases of Down's syndrome the main abnormalities were cardiac, duodenal atresia and subtle digital anomalies. The two fetuses with triploidy showed a large hydropic placenta and holoprosencephaly respectively, and all five cases of Turner's syndrome demonstrated a cystic hygroma two of which were associated with hydrops. From the antenatal scans major anomalies were detected in 18 fetuses, however, chromosomal disease was suspected in only 15 cases. This was in part owing to a high false negative rate for cardiac anomalies (14 cases) in both routine and detailed scans. Owing to the diversity of anomalies present in chromosomal disease full assessment of the fetus is recommended with particular attention to the fetal heart, face, hands and feet. Specific anomalies are suggested for karyotype.

Fetal choroid plexus cysts: a prospective study and review of the literature

To determine the incidence and significance of fetal choroid plexus cysts, a prospective study was carried out at Queen's Medical Centre, Nottingham. The incidence of cysts was found to be 0.42% and the size of cysts varied from 3 to 13 mm with a mean diameter of 6.2 mm. Choroid plexus cysts were associated with other fetal abnormalities in three cases, two of which were subsequently found to have a chromosomal abnormality, one Trisomy 18 and one Trisomy 21. A review of the reported cases of choroid plexus cysts reveals an overall incidence of 5.8% for Trisomy 18. We therefore recommend that in patients with choroid plexus cysts a detailed scan should be carried out to look for the ultrasound markers of Trisomy 18. If there is an associated abnormality or cysts are large (13 mm or greater in diameter) and bilateral then a karyotyping should be carried out.