Severe shoulder dystocia with a small-for-gestationaI-age infant: a case report.

BACKGROUND: Severe shoulder dystocia is disproportionately associated with large-for-gestational-age infants. CASE: A nulliparous patient at 38 weeks' gestation had an uncomplicated antenatal course. Clinical pelvimetry revealed an acute-angle pubic arch but otherwise normal diameters, conjugate and sacral concavity. Pre-pregnancy BMI was 20.8 and she had had a 14-pound (6.4 kg) weight gain. She presented in labor and, with oxytocin augmentation, progressed to full dilation over 6 hours, followed by an 18-minute second stage. Severe shoulder dystocia was encountered, necessitating multiple maneuvers, and was resolved after 2 minutes with delivery of the posterior arm. The healthy infant weighed 2,289 g (< 5th percentile) and exhibited only transient shoulder weakness, which resolved completely within 1 hour of life. With informed consent, CT pelvimetry was performed within 24 hours postpartum for investigative purposes, revealing small pelvic inlet and at-threshold interischial diameter. CONCLUSION: Geometric analysis reveals that borderline adequate pelvimetry likely played a significant role in severe shoulder dystocia etiology, even with a small-for-gestational-age infant. We alert obstetric providers to the possibility of severe shoulder dystocia in patients with borderline adequate pelves on clinical examination, even when estimated fetal weight makes cephalopelvic disproportion unlikely.

Neonatal brain imaging and the identification of metabolic acidemia and hypoxic-ischemic encephalopathy.

OBJECTIVE: To determine the precision with which intrapartum metabolic acidemia and hypoxic-ischemic encephalopathy (HIE) in term and near-term infants can be identified by neonatal brain imaging. STUDY DESIGN: This is a case-control study whose inclusion criteria were neonates born at > or =34 weeks gestation with a cord gas at delivery, suspected neurological abnormalities, and computed tomography (CT) or magnetic resonance (MR) imaging of the brain. Neonates with chromosomal and major congenital malformations were excluded. Brain imaging for neonates with and without metabolic acidemia (pH < 7.0 and base deficit > 12 mM) at birth and HIE were retrospectively reviewed by a neuroradiologist blinded to their clinical course and compared. RESULTS: There were 54 neonates admitted to the NICU at a single university hospital between 1992 and 2006 that met these inclusion criteria of which 27 had metabolic acidemia at birth. There were 16 diagnosed clinically as having HIE at the time of neonatal discharge, 13 from the acidemic group and 3 from the nonacidemic group. Radiological signs of basal ganglia injury were significantly more common in neonates with metabolic acidemia (29.6%, 3.7%, p = 0.02) and HIE (37.5%, 7.9%, p = 0.01). Logistic regression corrected for gestational age showed that radiological signs of basal ganglia injury could identify the presence of HIE with area under the ROC curve of 0.71, sensitivity 37.5%, specificity 92.1%, positive predictive value 66.7%, and negative predictive value of 77.8%. CONCLUSION: Radiological signs of basal ganglia injury on early neonatal imaging are associated with metabolic acidemia and HIE, but is not precise enough to serve as a gold standard in the identification of these conditions.

A systematic review of the role of intrapartum hypoxia-ischemia in the causation of neonatal encephalopathy.

The object of this review was to determine the incidence, morbidity, and mortality of an umbilical arterial pH < 7.0; the incidence of hypoxic-ischemic encephalopathy; and the proportion of cerebral palsy associated with intrapartum hypoxia-ischemia in nonanomalous term infants. A systematic review of the English language literature on the association between intrapartum hypoxia-ischemia and neonatal encephalopathy was conducted by using Pubmed and Embase. For nonanomalous term infants, the incidence of an umbilical arterial pH < 7.0 at birth is 3.7 of 1000, of which 51 of 297 (17.2%) survived with neonatal neurologic morbidity, 45 of 276 (16.3%) had seizures, and 24 of 407 (5.9%) died during the neonatal period. The incidence of neonatal neurologic morbidity and mortality for term infants born with cord pH < 7.0 was 23.1%. The incidence of hypoxic-ischemic encephalopathy is 2.5 of 1000 live births. The proportion of cerebral palsy associated with intrapartum hypoxia-ischemia is 14.5%. The vast majority of cases of cerebral palsy in nonanomalous term infants are not associated with intrapartum hypoxia-ischemia.