Autopsy reports for 29 very preterm infants dying at <28 days of age were reviewed. New findings were discovered in 79% and resulted in a significant change in diagnoses in 28%. Iatrogenic lesions were identified in 41% of cases and were the main cause of death in 14%.
- extreme prematurity
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When an extremely premature infant dies despite all intensive care efforts, it is accepted that the death certificate can be signed with the cause of death stated as “extreme prematurity”. This fails to specify the exact reason for death, which may be due to various causes. Although new information is often obtained after neonatal autopsy, infants of lower gestation and birth weight are less likely to be autopsied.1–,5 This paper reports the utility of autopsy in our unit for infants born <28 weeks gestation and dying in the first 28 days of life.
METHODS AND RESULTS
A retrospective medical record audit was undertaken of all deaths of infants born <28 weeks gestation and cared for in the neonatal intensive care unit from January 1995 to December 2003. All autopsies were undertaken by a perinatal pathologist (JZ). The main cause of death was determined for all infants dying in the first 28 days of life.
Of 387 infants born less than 28 weeks gestation during the study period, 314 (87.2%) survived to discharge and one infant died at home soon after discharge. A total of 74 infants (29 female and 45 male) died during the study period. Of these, 54 infants died <28 days of age, and 29 (54%) of these were autopsied. Table 1⇓ gives differences between those who did and did not have an autopsy. Infants who died <28 days of age and did not have an autopsy appeared to be slightly less mature and to have died sooner after birth. They were also less likely to be white.
For all but one of the 29 infants, the autopsy findings confirmed the specific reason for death. In one infant with sudden onset of pulmonary haemorrhage, the haemorrhage appeared to explain the failure to resuscitate but the reason for the pulmonary haemorrhage was not satisfactorily determined. In 23/29 (79%) cases, new diagnoses were discovered at autopsy. These are summarised in table 2⇓ along with the final diagnosis.
The autopsy findings led to a significant change in the clinical diagnoses in 8/29 (28%) cases. In 12/29 (41%) cases, iatrogenic lesions were identified, and in four of these (14% of all 29 cases) the iatrogenic lesion was the main cause of death. Table 3⇓ lists the iatrogenic lesions identified.
In this review, the autopsy added new information in nearly 80% of neonatal deaths for which extreme prematurity was thought to be the main cause of death. This resulted in a significant change in the main clinical diagnosis in 28% of cases.
Studies published over the last decade have shown low autopsy rates for preterm and very preterm infants.2–,5 Medical staff may not rate the autopsy as “very important” in cases of extreme prematurity.2 Because we have shown the value of autopsy for those of our very preterm infants dying in the first month of life, we now consider it routine care to seek consent for autopsy for these infants.
We restricted analysis of autopsy data to those infants dying less than 28 days of age, as we felt that infants dying early were most likely to be assessed as dying solely because of their extreme prematurity. We found a significant change in the main clinical diagnoses in 28% of infants. One of the reasons for discord was the recognition at autopsy of iatrogenic lesions in 41%. These ranged from minor abnormalities to injuries that were considered sufficient to be the main cause of death. Other studies have found iatrogenic lesions at rates of 4.4–15%.4,6,7 These rates may be lower than ours because of the inclusion of term infants. Awareness of iatrogenic lesions is important in auditing neonatal intensive care and can result in changes in policies and protocols. The extremely preterm infant appears to be particularly vulnerable to iatrogenic pathology, and in four of our cases this was the main cause of death.
We found that the autopsy information enabled us to be much more specific about the cause of death in these extremely premature infants. Some infants died because of complications of being born extremely preterm, such as lung disease of prematurity with air leak, whereas others died because of pregnancy and labour complications such as extreme growth retardation and perinatal asphyxia. The latter would probably previously have died in utero. An understanding of the true cause of death enables both the parents and the health professional caring for the baby to realise that death was inevitable and may assist in prognostication for infants being cared for in the future. It is recognised that the chance of finding new information appears to be at least partly dependent on the quality of the autopsy and therefore the experience of the pathologist.8 We are fortunate to have the services of an experienced perinatal pathologist, but most other tertiary and secondary perinatal units in New Zealand need to transport infants to Wellington for autopsy if they are to receive the same service.
This small study confirms the usefulness of autopsy when extreme prematurity is the main reason for death. This is especially so at the threshold of viability when it is important to understand why some of these very immature infants survive and why some do not. In our opinion the clinical experience gained in the past from autopsy on other extremely preterm infants helps the clinician to accept the inevitably of death when the outlook is extremely poor and be more confident when offering information and counsel to parents.
Thanks to Vaughan Richardson and Keith Fisher for assistance with access to the neonatal database.
Competing interests: none declared
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