The Tulip classification of perinatal mortality: introduction and multidisciplinary inter‐rater agreement

Abstract

Objective To introduce the pathophysiological Tulip classification system for underlying cause and mechanism of perinatal mortality based on clinical and pathological findings for the purpose of counselling and prevention.Design Descriptive.Setting Tertiary referral teaching hospital.Population Perinatally related deaths.Methods A classification consisting of groups of cause and mechanism of death was drawn up by a panel through the causal analysis of the events related to death. Individual classification of cause and mechanism was performed by assessors. Panel discussions were held for cases without consensus.Main outcome measures Inter-rater agreement for cause and mechanism of death.Results The classification consists of six main causes with subclassifications: (1) congenital anomaly (chromosomal, syndrome and single-or multiple-organ system), (2) placenta (placental bed, placental pathology, umbilical cord complication and not otherwise specified [NOS]), (3) prematurity (preterm prelabour rupture of membranes, preterm labour, cervical dysfunction, iatrogenous and NOS), (4) infection (transplacental, ascending, neonatal and NOS), (5) other (fetal hydrops of unknown origin, maternal disease, trauma and out of the ordinary) and (6) unknown. Overall kappa coefficient for agreement for cause was 0.81 (95% CI 0.80-0.83). Six mechanisms were drawn up: cardio/circulatory insufficiency, multi-organ failure, respiratory insufficiency, cerebral insufficiency, placental insufficiency and unknown. Overall kappa for mechanism was 0.72 (95% CI 0.70-0.74).Conclusions Classifying perinatal mortality to compare performance over time and between centres is useful and necessary. Interpretation of classifications demands consistency. The Tulip classification allows unambiguous classification of underlying cause and mechanism of perinatal mortality, gives a good inter-rater agreement, with a low percentage of unknown causes, and is easily applicable in a team of clinicians when guidelines are followed.

A Placental Cause of Intra-uterine Fetal Death Depends on the Perinatal Mortality Classification System Used

“…In our opinion asphyxia is not a cause of death but a clinical condition which is the result of an underlying cause of death and can be defined in many cases [4]. Similarly in the system of Hovatta et al 8.3% of cases were classified as ''asphyxia for unexplained reasons''. In fact these cases should be added to the cause of death group ''unknown'' and, therefore, their percentage of ''unknown'' increases from 21.6% to 29.9%.…”

“…Cause of death is based on the combination of clinical findings and diagnostic test results, including pathological findings for the purpose of counselling and prevention [8]. As our goal was to particularly focus on placental causes of death we discuss this part of the guideline.…”

“…No single system is universally accepted and each has strengths and weaknesses [8,9]. Problems occur during use and comparison of different systems.…”

“…Problems occur during use and comparison of different systems. Our research group developed a new classification system for perinatal mortality: the Tulip classification, in anticipation of current needs [8]. This system was designed by a multidisciplinary panel.…”

Evaluation of 1025 fetal deaths: proposed diagnostic workup

“…Therefore we prospectively analyzed all diagnostic tests of an extensive protocol in which the contribution of each test was evaluated for determining the cause of fetal death according to the Tulip classification. 7 Our goal was to propose a guideline for an optimal workup after fetal death in terms of a high percentage of explained fetal deaths in combination with a minimum of testing.…”