To determine the incidence of silent renal anomalies in infants with isolated single umbilical artery (SUA), all infants with SUA and without other obvious congenital anomalies, identified over a six year period, were screened using renal ultrasonography. Over 35 000 placentas were examined. An isolated single umbilical artery was identified in 112 (0-32%). Nineteen infants had abnormal renal imaging. Eight of 112 (7/1%) had significant persisting abnormalities. Vesicoureteric reflux was found in five infants (4-5/o were undertaken in all infants with abnormal renal imaging. ResultsOver 35 000 placentas were examined. SUA was present in 112 (0-32%). Nineteen infants had abnormalities on renal ultrasonography.Eight infants with SUA (7 1-%) had persistent significant abnormalities. The remaining 11 were normal on follow up renal imaging. Of those with persistent renal abnormalities (table 1) vesicoureteric reflux was a common finding, being present in five patients with SUA (4. 5%), and was bilateral in four of these.Three patients have so far had confirmed urinary tract infections. Two patients had morphological abnormalities unassociated with infection or vesicoureteric reflux; one had an isolated right megaureter and another had both kidneys on the left with one in the normal position and the other in the pelvis. The remaining patient had significant dilatation of the left collecting system but micturating cystourethrography was normal and the urine was sterile. The results of follow up renal investigations on this patient are awaited.The remaining 11 infants were subsequently shown not to have significant renal anomalies (see table 2). Discussion This is the largest study of renal anomalies in infants with isolated SUA. In the series ultrasonography was used as an initial screening procedure for all infants with SUA.The overall incidence of SUA in previous studies has varied from 0-2% to 1% which correlates well with our findings. The incidence of silent renal abnormalities in our study is less than that reported in studies by Feingold et a14 and Leung and Robson.10 Leung and Robson found five of 27 (18.5%) asymptomatic infants had underlying renal anomalies on screening with ultrasonography or intravenous pyelography. However, in their study only a small proportion of all infants with isolated SUA were screened. Although it is not indicated how infants were selected for screening, the authors note that the proportion of infants with anomalies was less when those in high risk groups were excluded. In our study, all infants identified with SUA had renal screening. The lower incidence of anomalies in our study might be accounted for by a lack of selection bias.

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Acquired methemoglobinemia is a potentially lethal medical condition caused by exposure to oxidizing xenobiotics, including antibiotics such as dapsone and inhaled anesthetics such as benzocaine. In this case report, we describe two presentations of acquired methemoglobinemia which presented to our surgical intensive care unit within one month. This highlights the potential connection between an emergent surgery or procedure and the development of methemoglobinemia in an environment where it is presumed that this condition would be extremely rare. High clinical suspicion for methemoglobinemia is warranted if the patient develops cyanosis or a decreased oxygen saturation unresponsive to supplemental oxygen when another etiology is not identifiable. If methemoglobinemia is suspected, a direct measurement of blood methemoglobin levels can be obtained to confirm the diagnosis. Prompt treatment with intravenous methylene blue is highly effective.